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Topography and morphology analysis of marine nanoparticles

and a pedagogical study of representations used for improving

a high school experiment

A thesis centered around a scanning electron microscope,

utilizing it in two vastly different ways

Robin Bramsäter

Examensarbete på programmet Civilingenjör och lärare inom området teknik och lärande

Stockholm 2012

Examiner: Lars Blomberg

Head Supervisor: Nickolay Ivchenko

Assistant Supervisor: Margareta Enghag

External Supervisor: Caroline Leck

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Abstract

The Arctic Summer Cloud Ocean Study expedition took place during the autumn of 2008 and brought

back water and air samples. One theory was that marine particles were shot into the atmosphere by

bubble bursting and, while in the atmosphere, acted as cloud condensation nuclei. Particles collected

from the subsurface water, surface microlayer and just above the surface had their topography and

morphology analyzed using a scanning electron microscope. Due to a lack of EDS analysis it's

impossible to say for sure if the particles found were the same found in previous studies, just that it

is highly likely that they are. No evidence against the marine particles being able to act as cloud

condensation nuclei was found but the data gathered was not sufficient to strengthen the theory

either.

The scanning electron microscope was also used in a pedagogical study, analyzing how operators

with different knowledge and prior experience interact with the microscope's images. These results

as well as knowledge gained from literature studies were used to improve a high school experiment

regarding centripetal acceleration. The main issue with the experiment was that what the students

learned performing the experiment was not the same as the theoretical models the teachers wished

the students to learn. The reason for this was because the experimental equipment lacked the

centripetal model's external representations such as force arrows. If a simulator would be

incorporated into the lab centripetal acceleration representations could be visualized and a clearer

connection between experiment and theory could be made.

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Content 1 Introduction .......................................................................................................................................... 9

2 Objectives ........................................................................................................................................... 11

2.1 The Duality of the Thesis ............................................................................................................. 11

2.2 Question Formulations ................................................................................................................ 11

2.3 Method ........................................................................................................................................ 11

2.4 Deliverables ................................................................................................................................. 11

3 Technical Background ......................................................................................................................... 13

3.1 The ASCOS (Arctic Summer Cloud Ocean Study) Project ............................................................ 13

3.2 Marine Particles ........................................................................................................................... 14

3.3 Aerosol Particles .......................................................................................................................... 15

3.4 Size Distributions ......................................................................................................................... 15

4 ASCOS Analysis ................................................................................................................................... 17

4.1 Method ........................................................................................................................................ 17

4.1.1 The Samples.......................................................................................................................... 17

4.1.2 Scanning Procedure .............................................................................................................. 17

4.1.3 Categorization ...................................................................................................................... 19

4.1.4 Preparation for the Statistical Analysis ................................................................................ 19

4.2 The Scanning Electron Microscope ............................................................................................. 20

4.2.1 General Concept ................................................................................................................... 20

4.2.2 The Electron Gun .................................................................................................................. 21

4.2.3 Magnetic Lenses ................................................................................................................... 22

4.2.4 Sample Loading .................................................................................................................... 23

4.2.5 Imaging ................................................................................................................................. 23

4.2.6 Focusing ................................................................................................................................ 24

4.2.7 Charge Effects ....................................................................................................................... 26

4.3 Results ......................................................................................................................................... 27

4.3.1 The Water Samples .............................................................................................................. 27

4.3.2 Subsurface Water Specific Particles ..................................................................................... 29

4.3.3 Surface Microlayer Specific Particles .................................................................................... 30

4.3.4 The Spray Samples ................................................................................................................ 31

5 The Scanning Electron Microscope and Its Representations ............................................................. 35

5.1 The Pedagogical Study ................................................................................................................. 35

5.1.1 The Goal of the Study ........................................................................................................... 35

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5.1.2 The SEM Experiment ............................................................................................................ 35

5.1.3 The SEM Task ........................................................................................................................ 35

5.1.4 Focus of the Experimental Study .......................................................................................... 36

5.1.5 The Interview Questions ...................................................................................................... 36

5.2 Theoretical Framework ............................................................................................................... 37

5.2.1 The Cognitive Load Theory ................................................................................................... 37

5.2.2 Problem Solving Strategies ................................................................................................... 37

5.2.3 External Representations ..................................................................................................... 38

5.2.4 Zone of Proximal Development (ZPD) .................................................................................. 40

5.2.5 Stimulated Recall .................................................................................................................. 40

5.3 Interview Results ......................................................................................................................... 41

5.3.1 Method of Analysis and Instrument Developed From Abductive Reasoning ...................... 41

5.3.2 Participants ........................................................................................................................... 41

5.3.3 Dictionary for "My" SEM Terms ........................................................................................... 42

5.3.4 Context for the SEM Operator.............................................................................................. 42

5.3.4 The Results ........................................................................................................................... 45

5.4 Interview Analysis ........................................................................................................................ 54

5.4.1 The Expert ............................................................................................................................. 54

5.4.2 The Intermediate .................................................................................................................. 54

5.4.3 The Novice ............................................................................................................................ 55

5.4.4 Comparing the Three ............................................................................................................ 55

5.4.5 Conclusion ............................................................................................................................ 56

6 Improving the Physics Experiment ..................................................................................................... 59

6.1 The Experiment ........................................................................................................................... 59

6.1.1 Background ........................................................................................................................... 59

6.1.2 Common Misinterpretations ................................................................................................ 60

6.2 Improvements ............................................................................................................................. 62

6.2.1 Comparison With the SEM Results ....................................................................................... 62

6.2.2 Clarifying the Theory Before the Experiment ....................................................................... 63

6.2.3 Solving the Experiment Task ................................................................................................ 64

6.2.4 Including a Simulator ............................................................................................................ 66

6.2.5 Summary............................................................................................................................... 67

7 Discussion ........................................................................................................................................... 69

7.1 The Marine Particles .................................................................................................................... 69

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7.1.1 Comparison With Previous Studies ...................................................................................... 69

7.1.2 Marine Gels .......................................................................................................................... 70

7.1.3 Particle Patterns ................................................................................................................... 71

7.1.4 Particle Size Distribution ...................................................................................................... 71

7.1.5 Reflections Regarding the Method ....................................................................................... 71

7.2 The Pedagogical Study ................................................................................................................. 72

7.2.1 Reflections Regarding the Method ....................................................................................... 72

7.2.2 Different Representations .................................................................................................... 73

7.2.3 Reflections Regarding the Improvements of the Experiment .............................................. 73

8 Conclusions ......................................................................................................................................... 75

8.1 The Marine Particles .................................................................................................................... 75

8.1.1 Future Work ......................................................................................................................... 75

8.1.2 CCN Coming From the Water ............................................................................................... 75

8.2 The Pedagogical Study ................................................................................................................. 75

8.2.1 Things to Consider When Creating a High School Experiment ............................................. 75

8.2.2 Educational Experiments ...................................................................................................... 75

References ............................................................................................................................................. 77

Literature ........................................................................................................................................... 77

Pictures .............................................................................................................................................. 78

Appendix 1 - The Interview Guide ......................................................................................................... 81

Appendix 2 - The Interview Transcriptions ........................................................................................... 83

The Expert ......................................................................................................................................... 83

The Intermediate ............................................................................................................................... 93

The Novice ....................................................................................................................................... 100

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1 Introduction The program Master of Science and Education was started in the year 2002 and was an effort to

create engineers with a pedagogical edge as well as teachers with the in depth knowledge of an

engineer. Consequently, the master thesis of this program requires research and work in both of the

fields which means this report consists mainly of two large parts: one technical part and one

pedagogical.

A lot of work during this master thesis was concentrated around the usage of a scanning electron

microscope (SEM) when analyzing marine particles collected during the ASCOS expedition during

2008. The main goals for the thesis were to analyze these particles, to analyze the external

representations used in the SEM and try to apply this information regarding representations in the

high school education.

The first half of this report focuses on the ASCOS analysis, where Chapter 3 contains theoretical

background and Chapter 4 is about the study which was carried out during this thesis. The second

half is the pedagogical part where Chapter 5 contains pedagogical theories and the SEM experiment

and Chapter 6 focuses on the high school experiment and how to improve it. The very last part

discusses the results from the technical and pedagogical studies and draws some conclusions.

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2 Objectives

2.1 The Duality of the Thesis This thesis has a technical and pedagogical part, both relating to a scanning electron microscope

(SEM). The technical part analyzes marine particles which were collected in the ASCOS expedition.

The pedagogical part is split into two parts. The first is strictly theoretical where a study revolving

around the SEM's representation is done. This is done by gaining knowledge from literature

regarding cognitive load theory and representations as well as a representations experiment

incorporating the SEM and three different users. The second half of the pedagogical part is to

improve a high school experiment regarding the centripetal acceleration.

2.2 Question Formulations The questions are split up into three categories: technical, theoretical pedagogy and practical

pedagogy.

What can be found in the marine samples collected during the ASCOS project 2008?

- Which different particles can be found?

- What are their size distributions?

- What shapes do they have?

How effective are the representations in the JEOL JSM-7401F's interface?

- Which representations are there and what impact do they have in the

interaction between the user and the scanning electron microscope?

- Which differences are there between expert and novice regarding which

representations are being used?

How can a high school experiment regarding the centripetal acceleration be performed and can

representations be incorporated?

2.3 Method The marine samples were analyzed using a scanning electron microscope of the type JEOL JSM-

7401F, taking pictures of the samples at 10 000x and 40 000x magnification. These pictures created

the foundation for the discussion (see Chapter 7).

To obtain information regarding the user-SEM interaction, several different operators were given a

simple task to carry out alone while the operating screen was being videotaped. Shortly after a

stimulated recall interview commenced. This knowledge combined with knowledge gained from

literature studies was used to improve a high school experiment.

2.4 Deliverables

- Some hundreds of pictures of the aerosol samples at 10 000x and 40 000x magnification

- Concrete examples to implement and test in the high school physics experiment

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3 Technical Background

3.1 The ASCOS (Arctic Summer Cloud Ocean Study) Project In the recent years, climate issues such as pollution, global warming etc have become huge

discussion subjects and the scientific interest regarding the climate has increased. A big part of

understanding the climate is to fully understand small airborne particles: aerosols. The ASCOS project

contributed with valuable scientific data with its expedition to the Arctic where it gathered both

aerosol and water samples. The ASCOS expedition took place in early August 2008, its goal being to

drift with the pack ice in the central Arctic while studying the processes which determine the

creation and life-cycle of clouds.

One of the theories was that tiny organic particles (microcolloids), which originally only had been

observed in the uppermost water layer , also could be found in the air. When these particles are up

in the atmosphere they are able to act as cloud condensation nuclei (CCN) and thus play a crucial role

for the cloud formation. When the sun's radiation heats up the water, tiny bubbles are created.

These bubbles reach the water surface and burst, shooting the microcolloids out of the water and

into the air. Since the clouds reflect sunlight, fewer bubbles will be created and consequently fewer

CCN will be able to form clouds. This is called climate feedback (see Figure 3.1) and is a totally natural

process since the human pollution and interference in the Arctic is very negligible (ASCOS Preliminary

Report).

Figure 3.1: The climate feedback process (From ASCOS Preliminary Report)

Several samples from different places were collected during the expedition. Surface microlayer (SML)

samples were collected from open leads with a rotating drum where the water got stuck to the

surface of the drum and subsequently dripped into a container. Subsurface water (SSW) was

collected at the same location at a depth of 0.5 meters. Multi-stage Berner cascade impactors were

used at a height of 23 meters above sea level for collecting aerosol particles. (Gao, 2012).

Artificial bubbling was conducted both inside a lab and in situ. Inside the lab a glass tower was used

where bubbles were generated by air being blown into the water from the bottom. The particles

from bubble bursting were collected over the water surface with a collection time of one hour. For

the in situ collection a bubble source was positioned 15 cm below the water surface and the particles

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were collected from the bubble bursting 10 cm above the surface (Gao). Figure 3.2 depicts the

bubble bursting process.

Figure 3.2 When a bubble reaches the water surface it bursts. Particles on the bubble surface are being shot into the atmosphere (c-d) and jet drops are subsequently following as the surrounding water fills the gap from the bubble (e-f)

(From College of Environmental Science and Forestry).

Newly formed fresh sea ice as well as algal assemblages loosely attached to the bottom of ice floes

were also collected (Gao).

3.2 Marine Particles There is a wide variety of oceanic particles such as sea salts and micro-organisms (e.g. bacteria and

virus-like particles) (Leck & Bigg, 2005). The ocean is also an important factor in biogeochemical

carbon cycling as it contains a large amount of reduced organic carbon which is mostly in the form of

dissolved organic carbon (DOC) polymers (Verdugo & Santschi, 2010).

Verdugo (2011) mentions four different processes: assembly, annealing, dispersion and

fragmentation. Assembly and annealing are processes when the nanoparticles entwine with each

other and create larger particles. Dispersion and fragmentation is the reversed process (see Figure

3.3).

The DOC polymers are imbedded in a solvent which hinders a collapse of the polymer network, these

stable polymer networks are what is called the marine gels. Typically the polymers are

interconnected by tangles and/or low energy bonds where the stability of these polymer networks

rely on a large amount of both tangles and energy bonds (Verdugo). This means that the assembly

and dispersion of the tangled polymers mainly depend on the polymers' length. The longer the

polymers the greater the possibility of them entwining and forming nanogels. These nanogels can

anneal with each other and form even larger particles: microgels (Ibid.). Assembling and annealing

are both reversible however and depend on the stability of the gels which in turn depends on factors

such as chain length, charge density, topology etc.

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Figure 3.3 DOC polymers are able to self-assemble into nanogels which are stabilized by entanglements and calcium bonds. The nanogels can in turn anneal with each other creating microgels. Both of these processes are reversible. (From

Verdugo, 2011)

3.3 Aerosol Particles Aerosols are suspensions of solid and/or liquid particles in the air, and are on a global scale mainly

derived from natural sources such as volcanic eruptions and sea salt. Sea salts and dust particles

mainly reside in the troposphere whereas the volcanic ashes are transported by upward winds to

higher altitudes and ultimately end up in the stratosphere. There are also external aerosols such as

meteoric smoke which is created when meteors are evaporated in the mesosphere. Besides these

naturally occurring aerosols, manmade ones are created mainly from combustion and can be found

in industrialized and heavily populated areas. These are just a few examples of the particles which go

under the label "atmospheric aerosol", all having different compositions, shapes, optical depths and

sizes where the size of an aerosol ranges from a few nanometers to several tens of a micrometer

(Chin, 2009).

Some aerosols affect the human health while other aerosols act as cloud condensation nuclei (CCN).

A CCN is a particle, typically around 200 nm in diameter (Eastern Illinois University), which captures

water droplets and in a large scale with other nuclei ultimately form clouds (Hamill, Jensen, Russell &

Bauman , 1997). Some of these aerosols reflect and scatter the sunlight, acting as a coolant for the

Earth, while others reflect sunlight coming from the Earth back again in a manner like greenhouse

gases. In the industrialized and more heavily populated areas the aerosols create health issues and

cause lung diseases to the areas' inhabitants, both humans and animals (Chin).

3.4 Size Distributions The size distribution, for both the aerosols and the marine particles, can be represented by a curve

which normally has four distinct peaks. An example of such a curve can be seen in Figure 3.4.

The first peak is called the nucleation mode and consists of particles less than 0.01 µm in diameter.

Due to the very small sizes of these particles it is rather hard to get a detailed picture of them

(College of Environmental Science and Forestry, 2012).

The second peak is called the Aitken mode and normally consists of organically derived virus-like

particles (Gao). These particles are in the size range of 0.01-0.1 µm.

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The third peak is called the accumulation mode and the particles here are in the size range of 0.1-1

µm. These particles are created by coagulation of smaller particles (New Media Studio, 2012) and

condensation of organic vapors onto microcolloid aggregates (Gao).

The coarse mode is the last peak and consists of particles larger than 1 µm which typically are sea

salts, bacteria and particles of multiple-source original (Ibid.).

Figure 3.4 The particle size distribtuion curve and with pictures of particles which are typically found in the different modes. (From College of Environmental Science and Forestry)

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4 ASCOS Analysis

4.1 Method

4.1.1 The Samples

The particles were collected at TEM grids (Figure 4.1), i.e. grids normally used for transmission

electron microscopy. These are circular copper rings with a checkered copper grid, about 3mm in

diameter.

Figure 4.1: The shape of the TEM grids being used (From Radboud Universiteit Nijmegen)

The different objectives were to gather statistical data and data regarding the particles' geometry

and chemical composition. The statistical data was obtained by taking plenty of pictures at 40 000x

(40k) magnification, the geometrical data was obtained by photographing interesting areas at 40k

magnification as well as looking at the more general picture gained from all of the 10 000x (10k)

pictures. After the pictures were taken and the observed particles had been categorized the samples

were supposed to be coated in platinum and the chemical composition analysis using EDS was to be

done.

Four samples were studied: one from the SSW, one from the SML and two from bubble bursting in

situ (the bubble bursting in situ will be referred to as spray samples).

4.1.2 Scanning Procedure

The checkered surface of the TEM grid makes orientation very easy. In order to achieve an effective

and thorough study each grid was divided into four quadrants where the best looking (i.e. least

damaged) quadrant would be analyzed. Beginning from the middle going radially outwards following

the quadrant's diagonal (i.e. 1,1; 2,2; 3,3, etc), each square was carefully studied at higher

magnifications.

Figure 4.2: The map over the TEM grid, the notation being: quadrant, horizontal coordinate, vertical coordinate (e.g. a,1,1). The coordinates for the empty squares follow the same pattern.

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Before taking any pictures at all, the grid was rotated so it represented the map in Figure 4.2. Since

the TEM grids had a asymmetrical object in the middle it was easy to rotate the grid so the object

was in the same position for each study. A working distance of 3.5mm was used with a sample height

of 1.9mm. The acceleration voltage was 3.00 kV with a -2.00 kV voltage over the sample (i.e. 1.00 kV

Gentle Beam), using the SEI (secondary electron imaging) detector and an electron current of 20 µA.

The picture was first focused as best as possible by looking at the sharpness of the grid lines. After

this was done a small hole was located and the beam alignment was corrected by wobbling the beam

and adjusting accordingly. When adjusting the astigmatism the goal was to have the hole as circular

as possible, easily spotting the over- and underfocus when the hole began turning oval. All of the

three steps (focus, beam alignment and stigmatism) were repeated several times until the picture

was of desirable quality.

For each sample (i.e. for each TEM grid) 7 squares in a diagonal was studied. For each square, 20-25

pictures was taken at a magnification of 10k and a single picture at 1000x (1k). Around 100 pictures

at a magnification of 40k was evenly spread out over the 7 squares. Since areas previously

photographed are damaged by the microscope, it was easy to spot where pictures have previously

been taken. The damage is not as severe as it sounds but a mere darkening of a previously studied

area (see Figure 4.3 and Figure 4.14). By taking the 1k photograph after all of the 10k pictures it was

possible to get a map over the square with each 10k picture marked out. By using a consistent

pattern when taking the 10k photographs each individual picture was traceable by using the map.

Figure 4.3 An overview picture of a TEM square. The red numbers are not part of the original picture but have been added afterwards to demonstrate the pattern being used when taking the 10 000x pictures

The 10k pictures were to get a general picture over the grid while the 40k pictures were to be used

for determining the form and geometry of the particles as well as being used in statistical analysis.

Due to the qualitatively reasons for the 40k pictures, areas of interest detected in the 10k pictures

were gone back to and photographed with the larger magnification.

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4.1.3 Categorization

The particles found were categorized with respect to their shape and no consideration was taken to

earlier scientific studies . This was done so any hasty conclusions would not be drawn and to keep it

as objective as possible. Subjectivity still sneaks its way in however since it was personal judgment

that determined whether or not two different particles were of the same kind or if they were

distinguishable as two different particle types. The comparison between this report's categories and

the scientific reports' as well as the analysis can be found in Chapter 7.1.

4.1.4 Preparation for the Statistical Analysis

The statistical analysis was carried out by another person involved in the ASCOS project but I will

include a brief description of how it works. A program is used which is able to distinguish distinct

particles in a picture. By telling the program at what magnification the pictures were taken at it will

calculate how many distinct particles there are and their sizes. In order for a picture to be usable the

particles need to be easily distinguishable and have sharp edges. If the picture has any astigmatism

or charge effects the particles tend to get blurry which results in the program calculating them being

larger than they actually are. A picture with good quality is not enough however, it needs to be in a

binary form (i.e. two colors only), not in grayscale which a picture normally is in. There are options in

the program which allows to determine which parts of the grayscale shall be converted to the binary

colors. In Figure 4.4 we see an example of a binary conversion where a grayscale picture (Figure 4.4

left) of three particles is converted into a black and white picture (Figure 4.4 middle) and ultimately

letting the program analyze where the particles are (Figure 4.4 right).

Figure 4.4 A SEM picture to the left, converted to a binary form in the middle then having the program analyze the particles (outlined to the right). The program includes a table of the particle areas in the picture being analyzed. The

freeware ImageJ has been used for this example but that is not the same program as the ASCOS researcher uses.

The purpose of the statistical analysis is not to see how large portion of the grids are covered in

particles but rather to see the size distributions between the observed particles. This size distribution

is plotted which, with a sufficient amount of data, should be able to reveal the Aitken and

accumulation modes.

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4.2 The Scanning Electron Microscope The instrument used for the electron microscopy was the JEOL JSM-7401F and the following text is

based on the web literature from The Northern Arizona University's course regarding micro probing.

4.2.1 General Concept

Very small objects and their structures have peaked the interest of scientists for many centuries. For

a very long time the magnification has been limited to that of the light microscope. The limiting

factor has been the de Broglie wavelength

where h is planck’s constant, p is the momentum, m the mass and v the velocity. Take the following

example to get an impression of the light microscope's resolution. A photon with an energy of 1 eV

has a wavelength of 1240 nm which means the highest achievable resolution is 1,24 µm in a light

microscope, using photons with this energy. However, the wavelength is decreasing as the mass of

the particle is increasing which is why electrons are used instead of photons. An electron with a

kinetic energy of 1 eV results in a de Broglie wavelength of 1,23 nm, i.e. more than 1000 times

greater magnification than that of a classic light microscope.

In a scanning electron microscope (SEM), the electrons are accelerated in a vacuum to a desired

kinetic energy, focused with magnetic lenses then shot at the prepared sample one wishes to study.

Figure 4.5 shows a simplified model of the SEM. The electron needs a very high mean free path in

order to minimize interference and is done by having a very high vacuum inside of the microscope.

Figure 4.5: A very simple model of the SEM

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When an electron hits the sample, it either scatters elastically or inelastically. In the elastic

scattering, only the electron's trajectory changes while the kinetic energy remains constant. During

the inelastic scattering, the incident electron will sometimes collide and displace an electron from

some of the sample's nuclei. If a displacement occurs an electron from the nucleus' outer shell will fill

the gap, resulting in an emitted photon, i.e. an X-ray.

The electron microscope consists of an electron gun which creates the electron beam. The beam is

focused by several condenser lenses in a vacuum. When the beam finally reaches the sample there

are detectors which detect primary, secondary and backscatter electrons as well as X-rays from

excited atoms. When an electron hits the sample its direction will change in a new direction with

each collision which can be modeled using the Monte Carlos method. Most of the incoming electrons

are absorbed into the actual sample and very few are able to escape the surface and reach the

detectors. The depth and width, i.e. the spread, of the electron's path inside of the sample is known

as the interaction volume and the lesser the volume the greater the quality of the topography

picture. Figure 4.6 shows an example of an interaction volume Monte Carlos simulation.

Figure 4.6: A Monte Carlos simulation of the interaction volume, simulating the paths of several different incident electrons. Electron absorbed in the sample are marked as blue and those which reached the surface are marked as red.

The sample's surface is located at the top (From Northern Arizona University)

4.2.2 The Electron Gun

The electron gun (Figure 4.7) creates the intense electron beam required for the scanning and for

this project a cold field emission gun was used. The electrons are gathered in a V-shaped tungsten

filament which is used as a cathode with the tip of the V pointing towards the anode. The tungsten

filament tip is held at several kilovolts negative potential relative to the nearby anode which creates

an electron point source at the tip of the V.

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Figure 4.7: A simple model of the electron gun (From Northern Arizona University)

Due to the tunneling effect, electrons from the electron source are able to overcome the potential

barrier required to escape the surface if the electrostatic field is strong enough. When they are in the

vacuum the electrons are accelerated by the electrostatic field and their kinetic energy is adjusted to

get a suitable wavelength to acquire the desired information from the sample. Low energy electrons

produce a lot of secondary electrons which gives more topographic information. High energy

electrons penetrate the sample easier and will create more backscatter electrons and X-rays, giving

information about the sample's chemical composition. The anode is used to change the voltage and

in doing so, adjusting the energy of the electron beam.

4.2.3 Magnetic Lenses

Similar to a light microscope, the electron microscope uses a lens system. These lenses are not

optical but magnetic and focus the electron beam. A magnetic lens (Figure 4.8) is a coil with a current

inside it which in turn creates a magnetic field. This magnetic field varies in magnitude and direction

depending on the position in the coil. When an electron passes through the coil it will be pushed

around by the varying magnetic forces and by adjusting these lenses the SEM operator is able to

adjust the beam. In a SEM there are typically four lenses, first two condenser lenses, after those a

scanning coil and lastly an objective lens (which is a kind of condenser lens).

Figure 4.8: The general concept for a magnetic lens (From Wikipedia)

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4.2.3.1 Condenser Lenses

The condenser lenses decrease the spot size of the electron beam. When the current in the lens is

increased, more electrons are diverted out of the beam, thus making it more and more narrow. This

means that the resolution is increasing the higher the current, but the number of secondary

electrons created are decreasing (since more are being diverted by the strong magnetic field).

4.2.3.2 Scanning Coils

There are two sets of scanning coils, one for raster and one for deflection. The coils move the beam

over the sample surface in two perpendicular directions, creating a squared area.

4.2.3.3 Objective Lens

The objective lens (sometimes called the final condenser lens) focuses the beam even more, though

without any electron losses.

4.2.4 Sample Loading

Due to the vacuum inside of the SEM, the sample first needs to be loaded into an airlock. The

samples are very small, 3 mm in diameter, and are placed in special holders which secure the

samples. Once inside the airlock, the pressure begins to drop until it reaches the same pressure as

inside of the SEM. When it reaches equal pressure a hatch to the microscope opens up and the

sample is pushed into place by the operator. When the sample is at the sample stage it is possible to

both tilt the sample and also adjust its height in order to get a good focus. If the sample is not

conductive it might be necessary to spray it with some gold in order to get a good image. When

analyzing organic samples with the EDS (Energy-dispersive X-ray Spectroscopy, a high energy beam

used to obtain knowledge regarding chemical composition) it is necessary to coat the sample in

platinum. This is required since the EDS beam will evaporate the parts being looked at without a

protective coating.

4.2.5 Imaging

4.2.5.1 Secondary Electrons

There are two types of electrons: one which indicate the topography and one which indicates the

atomic mass distribution of the sample. The ones indicating the topography are the secondary

electrons which are electrons from the sample which have been excited due to a collision with an

incident electron from the electron beam. These secondary electrons undergo elastic and inelastic

scattering while they move around in the sample (see Figure 4.6). Eventually some of the electrons

reach the specimen surface where they will escape if they have a sufficient amount of kinetic energy.

Secondary electrons have very low energy which means only the ones closest to the surface will be

able to escape and be detected.

The amount of electrons detected from different parts of the sample will create more or less bright

parts which reveal the topography of it. This is known as the edge effect and is present because the

detector registers more electrons if the surface is tilting towards the detector, giving a higher

secondary electron yield. Figure 4.9 shows a visual example of this phenomenon.

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Figure 4.9: A higher SE yield creates the edge effect (From Northern Arizona University)

4.2.5.2 Backscatter Electrons

The second kind are the backscatter electrons. These are high energy electrons which are elastically

scattered, i.e. reflected, by the specimen's atomic nuclei. The higher the average atomic number, the

stronger the backscattering and the brighter the image. The backscatter electrons are thus used to

differentiate parts of the specimen that have different average atomic number.

4.2.5.3 Excitation and De-excitation of Atoms

As was just mentioned, during the inelastic scattering the incident neutron sometimes excites an

atom. When the atom after some time returns to a de-excited state it releases an excess energy

which can be in the form of an X-ray, cathodoluminescence and Auger electrons. Each element has a

very characteristic relaxation energy and will thus reveal what kind of chemical composition the

specimen consists of.

4.2.5.4 Gentle Beam

The image quality depends ultimately on the probe current (i.e. amount of electrons hitting the

sample) which is also known as the spot size. The narrower the spot size, the better the resolution.

The spot size can be narrowed down by increasing the acceleration voltage, which in turn creates a

high interaction volume which is bad for the topography quality. By using a function in the JEOL JSM-

7401F called "Gentle Beam", it is possible to apply a negative voltage over the sample which reduces

the velocity of the incoming electrons. An example would be to have the sample under -2.00 kV while

using an acceleration voltage of 3.00 kV. The interaction volume would be small (the same size as if

one would use a 1.00 kV acceleration voltage) and the spot size would be small as well since the

acceleration voltage actually is 3.00 kV.

Another reason to use the gentle beam function is due to non-conductive samples tend to get

damaged at higher voltages. By using the gentle beam, both the image quality is increased and

sample damage reduced.

4.2.6 Focusing

When focusing the beam, there are basically three different steps which are repeated over and over

until the operator is satisfied with the image quality. These three steps are adjusting the focal length

(also known as working distance), aligning the apertures (condensation lenses and objective lens)

and correcting astigmatism.

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4.2.6.1 Working Distance

Just like in light optics, the lens system of the SEM has a focal point. The sample stage, where the

sample is located, can be moved up and down by a knob on the side of the microscope. This is used

for very rough focusing and is only done at the very beginning. It is mainly to get a picture at all since

at the start of studying a new sample the image screen only shows black and white static. This is

normally done at low magnification (~500x).

When one is satisfied with the focus (i.e. when it is impossible to get a better focus by just adjusting

the height) it is time to adjust the beam's focal point. In comparison with the previous stage, this

adjusts the beam while the sample is stationary while in the first step the sample stage was being

moved while the beam's focal length was fixed. The beam's focal length is called the working

distance and can be changed either by rotating a knob on the operating panel or by sliding a bar in

the computer interface. This is done throughout the entire focusing process and will be referred to as

"focusing".

4.2.6.2 Aperture Alignment

When focusing at higher magnification one might notice that the sample moves around. This is

because the electron beam is not aligned correctly which also affects the image quality. By turning on

the wobbler function the sample is being brought in and out of focus, making the picture jump

around quite a lot (see Figure 4.10). The goal here is to shift alignment in the X- and Y-axis until the

sample is not moving. A good strategy is to start with one axis, making the sample just move either

horizontally or vertically and thereafter correct the second axis.

Figure 4.10: The beam paths and the image during the wobbling (From Protrain)

4.2.6.3 Astigmatism

Astigmatism is created when the condenser lenses magnifies one part more than another, creating a

stretched out image. The operator should always bring the image to focus before attempting to

correct the astigmatism. There are two stigmators, X and Y, which are used to correct the

astigmatism, and the operator might have to alternate between these and re-focusing if the

astigmatism is severe. The image will get stretched out in one way during overfocus and stretched

out in the other during underfocus (see Figure 4.11 and Figure 4.12). Going in and out of focus is a

26

good way of telling if the astigmatism corrections have been successful. If it gets more blurry the

more out of focus the image gets the astigmatism is corrected, if it is getting stretched out the

astigmatism still needs some work. Normally these corrections are made at a magnification greater

than the working magnification, so that the images taken at the working magnification will not be

spoiled if the operator does not make a perfect correction.

Figure 4.11: The image stretching observed during astigmatism and also when it is corrected (From Protrain)

Figure 4.12: An example of what the stretching looks like during under- and overfocus (From Protrain)

4.2.7 Charge Effects

The charge effect has a big impact on the image quality and is due to an excess buildup of electrons

on the surface of the sample. This effect gets more common the less conductive the sample is. A

charged up area will create an electric field which deflects incoming electrons, appearing as bright

white on the image.

This is common when first adjusting the focus since a small part of the sample will be exposed to the

electron beam for a long time. A good way around this problem is to do the initial focus at a place

27

which will not be studied later, leaving the more interesting parts still uncharged. If the parts which

are to be photographed still gets charged there are some solutions: decrease the acceleration

voltage, reduce the spot size, lower the vacuum and let the gas absorb some electrons, or lastly, coat

the sample in a conductive layer.

4.3 Results The results will be split up in four parts: particles found both in the SSW and SML, particles found

only in the SSW, particles found only in the SML and particles found from the the spray samples,

including a description of the particles found.

4.3.1 The Water Samples

These samples are from the subsurface water (SSW) and the surface microlayer (SML). Many of the

particles appear both in the SSW and the SML which is why I chose to combine the two categories

into one. The SML had typically more very small particles, some areas looking like a galaxy full of

stars where as the SSW had a more barren characteristic with slightly larger particles. The following

categories will include an example from the SSW to the left and from the SML to the right.

4.3.1.1 Small Grains

Typically in the size range of 100-200 nm, these grains were commonly found across the sample,

increasing in abundance closer to the middle. They had a distinct three dimensional topography,

often with a slightly knobby surface and asymmetrical shapes.

Figure 4.13 The small grains from the SSW (left, 40k magnification) tended to be slightly larger than the ones from the SML (right, 43k magnification).

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4.3.1.2 Diffuse Strings

Ranging from several micrometers to tens of micrometers, these strings appeared as diffuse white

shapes across the TEM grids. Some squares had very long strings while other were quite devoid of

them with just a short stump somewhere. The strings were not showing any three dimensional

structure and sometimes contained other particles inside/on top of them.

Figure 4.14 A diffuse string from the SSW to the left in 10k magnification and an overview of a square from the SML to the right (1k magnification) showing the spread some of the strings had.

4.3.1.3 Nanoparticles

Very small particles (only a few nanometers to some tens of nanometers in diameter). Sometimes

lying together in larger groups and sometimes as a lone particle.

Figure 4.15 Several nanoparticles from the SSW sample and a lone particle from the SML sample. Both pictures are taken in 40k magnification.

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4.3.1.4 Mucus

Areas of two dimensional mucus were frequently spotted. They had a smooth surface but were fairly

diffuse when trying to focus on them. The sizes of them varied greatly, from some hundreds of

nanometers to several micrometers.

Figure 4.16 A small area of mucus to the left (40k magnification) and a large area of mucus to the right (16k magnification).

4.3.2 Subsurface Water Specific Particles

Two different kind of particle formations where found only in the SSW samples: small clusters and

halos

4.3.2.1 Small Clusters

What seems to be nanoparticles clumped up in small chains or clusters. They were seen together

with other small clusters or with small grains in a near vicinity.

Figure 4.17 A few small clusters and a bit of mucus to the left and to the right we see a few small clusters, some scattered nanoparticles, a bit of mucus and a few small grains. Both pictures are taken at 40k magnification.

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4.3.2.2 Halo

Consists of a larger core which either seemed to be a large particle (Figure 4.18, left part) or several

small particles held together in some electron transparent material (Figure 4.18, right part). These

halos were rarely spotted and only 2-3 were observed in all of the SSW samples.

Figure 4.18 Two kinds of halos, both taken in 10k magnification. The left particle has a much smaller halo than the right one. Small particles inside of the right core are visible. In the left picture we see some scattered nanoparticles.

4.3.3 Surface Microlayer Specific Particles

Crystals and huge gatherings of nanoparticles (what I chose to call shimmer) was only found in the

SML samples.

4.3.3.1 Shimmer

The shimmer was mostly large areas, often some micrometers in width and length, containing lots of

very small (some nanometers in diameter) particles. Often having a very well defined edge where

there is almost like an outline around the shimmer (though not always the case, on some occasions

the shimmer gradually disappeared). The visibility of the particles also varied quite a lot, from barely

being visible to looking like a galaxy of very bright stars (as seen in Figure 4.19).

Figure 4.19 Very bright shimmer (10k magnification) and a closer look at the mucus to the top left (40k magnification).

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4.3.3.2 Crystals

A few crystalline particles were found throughout the SML samples. These were quite rare and only a

few crystals were spotted. Their edges were very distinct and sharp unlike the soft edges like those of

the small grains.

Figure 4.20 Different forms of crystals, both pictures taken at 40k magnification. To the left we see some mucus as well.

4.3.4 The Spray Samples

The spray samples were a lot more barren and devoid of small particles compared to the water

samples. What these samples had, however, were very large particles in the size of several

micrometers in diameter. The samples also had a substance which was sensitive to the electron

beam and vaporized under too long exposure.

4.3.4.1 Assemblies

These particles were commonly found varying in shape and size, all seeming to be assembled by

small lumps. They were normally found in sizes ranging between some hundreds of nanometers to

several micrometers. There were however some very large ones as well, being up to ten micrometer

in size.

Figure 4.21 The assemblies in different shapes. Left in 10k magnification and right in 40k magnification

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Figure 4.22 A very large assembly with a particle from Figure 4.21 edited in to give perspective to the size. The picture is taken at 11k magnification and the small particle has been resized accordingly.

4.3.4.2 Fragile Gel

This mucus-like substance was found occasionally and vaporized by an intense electron beam

(achieved by a high magnification) or by long exposure. At high magnification the magnified area

would completely disappear while during the exposure the gel would slowly recede starting from the

outer edges slowly disappearing inwards.

Figure 4.23 To the left we see fragile gel damaged by very high magnification (picture taken at 30k magnification). To the right we see a picture of fragile gel taken by freezing the image, exposing the gel for a long time making it recede from

the outer line towards the middle.

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4.3.4.3 Nanoparticles

Similar to those found in the surface microlayer samples but a lot less frequently found. Rather than

seeing them in clusters (see left part of Figure 4.15) they were often found alone in a very barren

area.

Figure 4.24 One nanoparticle seen in 10k magnification (left) and two others seen in 40k magnification (right).

4.3.4.4 Small Clusters

Similar to those found in the SSW samples, these clusters also seemed to be composed of

nanoparticles. These sometimes formed even more compact structures though, almost looking like

solid flakes. The clusters were a lot less frequently found when compared to SSW ones.

Figure 4.25 A flake (left, 40k magnification) and clusters (right, 40k magnification) resembling those in Figure 4.17.

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35

5 The Scanning Electron Microscope and Its Representations

5.1 The Pedagogical Study

5.1.1 The Goal of the Study

The pedagogical part of this master thesis was to study the interaction between a user and a JEOL

electron microscope to see how they explained in what way their reasoning changed depending on

the feedback received from the operating screen. In order to do so an interview was necessary so

they could explain their thoughts while operating the instrument. To minimize disturbances while

operating the SEM, the interviewees were videotaped and undisturbed while performing a simple

task using the microscope, then later interviewed while watching certain selected parts of the video.

This method is called stimulated recall and is explained in Chapter 5.2.5.

These interview results were used, in combination with a literature study regarding external

representations and cognitive load theory, to further develop high school lab instructions for a

physics lab. I thus needed to know very specifically what I wanted to obtain from the interviews and

the SEM study.

5.1.2 The SEM Experiment

First of all, why use a SEM for this part? The obvious downsides are that it is expensive to use and

requires training before a person is allowed to operate it (thus limiting suitable interviewees).

However, when working with the SEM, the operator tries to manipulate the instrument in a way to

get the best resolution and image quality possible. This essentially means that the operator is

constantly working with an image, planning his next move depending on what feedback he has

gotten from the image he is working on. Operating experience helps out but due to the complexity of

the instrument solid physics knowledge regarding how the lens system etc works is also necessary.

This means, all in all, that the person operating a SEM has to plan ahead by using prior knowledge

and experience, then change the plans according to the feedback received from the image and adjust

the image by using knowledge regarding how the SEM works.

Three people volunteered to operate the instrument and to be interviewed afterwards. They ranged

greatly in experience where one person had been working for 30 years with the SEM, the second

person had been using the SEM for several years in a specific field but had never tried samples of the

kind which was being used for this study, and the last person was new to the SEM and had only been

using it for 3-4 weeks.

5.1.3 The SEM Task

All of the three people got the same instructions: a brief description of the sample and the task. The

sample was a TEM grid coated with a carbon fiber film with gold sputtered across it. It is a sample

which new operators get to practice on since it is highly conductive and easy to focus on. Detailed

pictures of what the sample looks like when viewed in the SEM is shown in Chapter 5.3.4.

The task can be split up into four parts and I will write them down as four separate steps to make the

whole task easier to overview.

1. The first part of the task was to find the smallest particle (or structure) the participant

deemed possible.

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2. When a particle or structure had been found the participant was to focus the beam as best

he or she could and get (according to him or her) the best possible quality.

3. This particle or structure was then to be measured by using a measuring tool which is built in

into the SEM interface.

4. Ultimately the participant was to take a picture of what he or she had achieved.

They got to use any settings they wanted and got complete freedom with no time restraints. Each

person started with the same settings at the same position and magnification.

5.1.4 Focus of the Experimental Study

Before conducting the experiment I needed to figure out exactly what feedback I wanted to obtain

from this research. I needed to know this in order to create the task for the test persons. This is when

I wrote an interview guide where I summarized my main questions and then started to break them

down in sub categories. These questions were:

What part in the interface is helping the user to intuitively progress in his problem solving

process?

What parts are excessive/confusing?

How does the user's prior knowledge affect his performance?

The finished guide can be found in Appendix 1. From this I started creating more specific questions

which were more easily observable. A few examples of such questions would be if the person had

performed a similar task earlier, what kind of plan the person had before taking on the task, what the

person did when the feedback received was not corresponding to his expectations etc. This guide

was to be used when creating the real and personally designed interview questions which I would ask

the interviewees.

5.1.5 The Interview Questions

Since there would be quite a lot of excessive material from the video tapes I knew I had to select

certain points of interest in the film to make the interview as effective as possible. When all the films

had been produced I sat down and looked through them, writing up different time stamps for each of

the questions I wanted to ask.

The questions for the three persons were all fairly similar where they all shared two identical

questions. The first question they received was what their plan was after first hearing their task. The

last question they received was why they were satisfied with the picture they took and why they

wanted to stop when they did.

Since each person used the instrument in a slightly different manner it was impossible to ask the

exact same questions and weigh the interview in a certain way. Instead I selected things in the films

when they performed an action which they had not done before and asked the reason for it. The

persons were obviously allowed to comment on things in the film on their own during the interview

if they wanted to. After the interviews I transcribed the audio files and started categorizing their

answers. This categorization and a compilation of the interviews can be found under Chapter 5.3.

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5.2 Theoretical Framework Representations are all around us all the time. They allow us to interpret our surroundings and

structure our cognitive processes when solving problems. There are mainly two types of

representations, internal and external. The internal representations can be compared to cognitive

schemata and the external ones are text, pictures, movies, music etc. With proper usage of different

external representations it is possible to decrease the work load of the cognitive processes which

increases the task focus and improves schema acquisition (van Bruggen, Kirschner & Jochems, 2002).

5.2.1 The Cognitive Load Theory

In cognitive load theory, knowledge is modeled as thought patterns stored in the long term memory

which are called schemata. When a person engages in a task and he possesses the proper schemata

to solve the task, the schemata will be activated and the relevant procedures to complete the

problem at hand will be carried out. These processes implemented by the schemata are automated

and thus requires less working memory (Ibid.).

If a schema, the way we interpret and interact with the world, does not correspond with what we

see, we try to adjust in one of two ways. One way to adjust is that we accommodate the situation

which means that we change our old schema or create new ones to better suit our new experience.

This process is called accommodation and an example of this would be of a person learning how to

eat with chopsticks. The person knows how to eat with western cutlery but needs to adjust his hands

in order to eat with the chopsticks (Piaget , 2008).

The other way we adjust to a situation is by a process called assimilation and is when we adjust our

new experiences according to our previous schemata. The same person in the previous example has

been served a new food which he has never seen before but he notices he can eat it the same way

like he has always eaten. The experience was new but old schemata could be used (Ibid.).

Sweller et al. (1988) introduced three different kinds of cognitive load. The intrinsic load is related to

the difficulty of a concept. For example is reading upside down is a lot harder and requires more

mental effort than reading the normal way. Extraneous load unnecessary cognitive load which is

caused by poor instructions. This can be compared with the germane load which is the cognitive load

which creates useful schemata. Sweller et al. describes the differences between these two as

"Although both can be altered by instructional interventions, extraneous cognitive load reflects the effort

required to process poorly designed instruction, whereas germane cognitive load reflects the effort that contributes to the construction of schemas. Appropriate instructional designs decrease extraneous cognitive load but increase germane cognitive load." (Sweller et al., 1988)

5.2.2 Problem Solving Strategies

There are several different approaches to solving a problem. One way is the means-end analysis

where the problem solver gets a problem with a clear goal and starts working backwards. Since a

novice does not have the required schemata to tell him which path to take in order to reach the goal

he instead looks at the goal itself to try and figure out the necessary steps. It is an effective method

but requires a great cognitive load since the problem solver needs to remember plenty of things at

the same time such as the problem, the goal, the relation between these two, problem solving

operations and, if sub goals have been used, a goal stack to keep track of which sub goals have been

finished and which ones are next. While this strategy has been proven to be effective for solving a

problem it has not been effective for educational purposes since the problem solver tends to not

38

obtain desirable schemata. He might learn how to solve problems of a similar kind but fails to

understand the underlying theories as to why the different steps he took were successful (Sweller,

1988).

The other approach for a novice problem solver would be to explore different paths and see what

information he can get. Even though the goal might be clear he begins at the starting point and

experiments his way forward, seeing what variables are possible to derive or what consequences

different decisions get. Having a clear goal tends to encourage people to a means-end strategy which

means that in an educational scenario open questions are more preferable - questions which asks the

problem solver to derive as much information as possible from a given start (Ibid.).

The third strategy would be if the problem solver is an expert. If he is an expert he has the required

schemata and knows exactly which steps to take, which sub goals are required to obtain the desired

results and does not need to neither explore different angles of the problem nor work his way

backwards (Ibid.).

These different strategies also appear in a study conducted by Kohl and Finkelstein (2008) in which

experts and novices got to solve different physics problems. There were two different physics

problems which had a heavy focus on representations. The first problem worked solely by analyzing

different representations whereas the second one was a calculation problem but was significantly

easier solved by incorporating some self-made representations while solving it.

What Kohl and Finkelstein noticed was that the novices and experts used about an equal amount of

different representations during their problem solving process, with the experts being more

successful and more effective. When working with the representations the experts, when compared

to the novices, spent a greater fraction of their time pursuing specific goals or subgoals, even when

not knowing exactly how to proceed (Kohl & Finkelstein, 2008). Novices also spent some time using

this technique but they were more likely to explore without a clear purpose with hopes of

discovering something which would help in the problem solving process (Ibid.).

5.2.3 External Representations

There are many kinds of external representations and according to Alty (1991) audio is good for

stimulating the creative thinking, movies to deliver information regarding a process or an action, text

to emphasize details and diagrams to explain a theory. An example of this would be to first stimulate

the creativity by some music, present a diagram with a theory the person is about to learn and

include some explanatory text to it. (Ibid.)

A creator of educational material has to be careful when including external representations. A

misguiding or confusing representation will make schema acquisition harder or in the worst case

erroneous, leading to an assimilation of the "bad" schemata (Scaife & Rogers, 1996). Scaife and

Rogers are using three different characteristics when analyzing external representations which are

computational offloading, re-representation and graphical constraining.

" [Computational offloading] refers to the extent to which differential external representations reduce

the amount of cognitive effort required to solve informationally equivalent problems." (Ibid). Larkin

and Simon illustrate this very well with a geometric example. Compare the geometry task seen in

Figure 5.1 in its purely sentential form and when accompanied by a diagram depicting the scenario.

39

The diagram offers easily obtained information regarding the location of different objects and how

they relate to each other which reduces a need to search and recognize. The geometry problem in its

sentential form requires a greater computational load to keep track of how the problem is

progressing. Possible states, consequences and object relations has to be explicitly formulated and

computed mentally in order to solve the problem purely in the sentential form (Scaife & Rogers)

which, of course, leads to a greater cognitive effort.

Figure 5.1: Verbal and diagrammatic representation of a geometry problem (From Larkin & Simon, 1987)

By using external representations in the forms of diagrams, pictures, movies etc the answer can

easier be read directly off of the representation rather than having to formulate the picture mentally

before acquiring the answer. This is a very clear example where the latter instruction clearly reduces

the extraneous load and increase the germane load.

This leads us in to re-representations which "[...] refers to how different external representations,

that have the same abstract structure, make problem-solving easier or more difficult." (Scaife &

Rogers). The previous geometric problem is still a good example, showing the different difficulties

between its sentential and half-graphical, half-sentential forms. Another example of this is that a

person today would have an easier time interpreting and solving the mathematical problem 67*10 in

arabic numerals rather than the roman equivalent LXVII*X (with the participant obviously being

informed of the latter being Roman numerals).

Graphical constraining refers to how the external representation limits and constrains different

inferences of a given problem or theory. The general idea is to force the interpreter of an external

representation to reach a certain conclusion, avoiding erroneous interpretations. The computational

offloading is increased by having good re-representations and graphical constraining (Ibid.). Another

way to look at good graphical constraining is that a representation should be fairly simple and should

not include a lot of rules to work with. The fewer rules a representation has and the less abstract it is

the easier it is for the problem solver to work with it and consequently easier to solve the original

40

task at hand. This can obviously backfire with a poorly designed diagram which forces the problem

solver to reach faulty conclusions.

5.2.4 Zone of Proximal Development (ZPD)

The Zone of Proximal Development is a theoretical development zone constructed by Lev Vygotskij.

He explains the zone as

"[...] the distance between the actual developmental level as determined by independent problem solving

and the level of potential development as determined through problem solving under adult guidance, or

in collaboration with more capable peers" (Vygotskij, 1978)

What he means by this is that the ZPD is the zone constructed by the difference between what a

learner can do without help with regards to what he or she could do with help. An example would be

of a person who wants to bake a cake but lacks the schemata required to do so. If the person gets

help by something which contains the required information (that can be a teacher, parent, a book, a

guide on the internet etc) the person will be able to bake the cake. This is not to be confused with

the person actually learning how to bake, he could have just followed instructions from a cooking

book and forgot what he did the moment he did it. Obtaining the correct schemata might take time

depending on the task and relies on the pedagogical level and effort by the learner.

5.2.5 Stimulated Recall

Stimulated recall is an interview technique where a person is video- or audio taped during a scenario

where the person is active (might be solving a task, talking to people etc). The person is later

interviewed while, together with the researcher, looking at the recorded material. This is to

stimulate and help the interviewed person to recall thought processes from the time of

documentation (Haglund, 2003).

There are some recommendations in order to take care of issues regarding memory, retrieval and

instructions (Mackey & Gass, 2005). These include, among some others, giving clear guidelines to

each participant (Schepens, Aelterman, & Van Keer, 2007), carrying out the stimulated recall

interview as soon as possible after the recorded scenario (Ibid.) and participants should be minimally

trained to enable them to carry out the procedure but they should not be cued to extra and

unnecessary knowledge (Mackey & Gass).

The advantages with using this technique is that people can carry on with their work, undisturbed by

questions from the researcher. The method has also been criticized by arguments questioning if the

interviewed person recalls the actual thought processes and feelings or creates them subconsciously

while looking at the documented material. Further criticism argues that the person might be

influenced by external stimuli which makes accurate recalling even harder (Haglund).

The reason I chose to use stimulated recall as an interview technique is because the criticism

regarding disturbances created by irrelevant external stimuli was negligible in this study. The test

person who was operating the scanning electron microscope was in a room with no other people in it

besides me and the operator himself. The only things which made any sounds or could catch

someone's attention were the image screens which means any excessive external stimuli were very

low. Another reason was that I did not want to create more cognitive load for the test persons' by

taking away some of their focus to answer questions during their time of operation.

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5.3 Interview Results

5.3.1 Method of Analysis and Instrument Developed From Abductive Reasoning

The whole purpose with this study was to see how people interacted with the SEM instrument when

solving a simple task. In the interviews the test person and I discussed what he or she did and what

the thought process and reasoning was behind it. In order to compare the different results and make

the analyzing a bit more manageable I categorized the answers in different areas which, in some

places, overlap each other (see Table 5.1).

Table 5.1 The tool used for categorizing the interview results

Planning

What kind of plan did the person have? Means-end analysis, experimentation or did the person know exactly which steps were necessary to complete the task?

Theoretical background

Did the person have any prior theoretical knowledge regarding the instrument and/or sample? Did the person know what to expect when executing certain actions?

Theoretical knowledge regarding screen feedback

Did the person know any underlying reasons for what he or she saw on the screen? I.e. did the person describe the picture simply as blurry or more specifically blurry due to X?

Experience

Did the person have any prior experiences regarding the instrument and/or sample? Had the person executed similar/the same actions before and knew what to expect?

Feedback response

What did the person do when encountering certain phenomena? E.g. if the screen was blurry, what actions did he or she take? How did the person respond to the received feedback?

Misinterpretations Did the person misinterpret the information given in the instructions or by the feedback received?

External help Did the person require any external help in the form of notes, people to ask or similar?

Exploration

Did the person undertake any exploration outside of his or her original plan? Did the person try things which he or she had never done before or did not know what the outcome would be?

Uncertainty

Was the person unsure of where to go or where to look? Was the person unsure of what to do with the received feedback or how to interpret the image?

5.3.2 Participants

Three people partook in this study, each having a different background and experience with the

instrument. I will rank them expert, intermediate and novice. The expert had 30 years of experience

working with the SEM and had a great theoretical knowledge. The intermediate had worked with the

instrument for 3-4 years in a certain field with great experience in this field but limited knowledge

and experience outside of it. The novice had worked with the SEM for 3-4 weeks with a brief

introductory course using the same sample used in the study, the person's knowledge and

experience were very limited. The different persons will be referred to as "he" regardless of their

actual gender.

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In order to avoid confusion for the reader a short dictionary regarding the different terms I have used

and are about to use will follow. My guess is that not many people have ever used a SEM before so I

will also include several pictures to explain what the test persons have been looking at.

5.3.3 Dictionary for "My" SEM Terms

Image - What the SEM operating screen is showing

Quick view - The image is getting frequently updated but with a rather poor image quality

Fine view- The image is being scanned from the top to the bottom (similar to taking a picture) with

good image quality but long update time.

Picture/photography - A picture taken using the Photo function on the SEM (an example of this is

shown in Figure 5.10). Gives a very detailed picture but charges the sample more easily since the

electron beam is scanning a small portion of the screen at a time.

Freeze photo - A picture taken by integrating several images in quick view over a preset amount of

time. Tends to give less charging in the picture than when taking a normal photography since the

electron beam is more evenly spread out.

LEI detector - The detector inside the SEM which registers the backscatter electrons

SEI detector - The detector inside the SEM which registers the secondary electrons

RDC window - A smaller window which is the only part of the screen which will be updated when

active. This means a smaller area being scanned and higher resolution in that window.

Focus (used as a verb) - Using the focusing knob which adjusts the working distance.

Focus (used as a noun) - The sharpness and resolution of the image and picture. This quality does not

only depend on the focusing knob but also from beam alignment, stigmatism, contaminations etc.

5.3.4 Context for the SEM Operator

The instrument's settings were all reset for each new person. These pictures are not gathered from a

single test person but gathered from the test group as a whole. I have included some pictures so

readers who are not familiar with using a SEM would get a better understanding of what it looks like

for a SEM operator.

Following is the view the persons were greeted with: the copper grid was clearly visible here and the

LEI detector was being used which made the squares bright (Figure 5.2). When focusing and

increasing magnification, the carbon pattern became a lot clearer (Figure 5.3) and the SEI detector

was being used, making the squares black.

Figure 5.2 The initial view when first starting the experiment Figure 5.3 The carbon pattern is visible

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Focusing, aligning the beam and adjusting astigmatism was done either around an edge or a hole

(Figure 5.4 and Figure 5.5). These edges are from the carbon structure seen in Figure 5.2, 5.3 and 5.6

Figure 5.4 An edge out of focus Figure 5.5 Another edge, with a hole, in focus

At this point the carbon structure was very clear (Figure 5.6) and small particles could be identified

and measured (Figure 5.7). The particle in Figure 5.7 is actually not on the carbon structure but lying

on the copper grid, next to the carbon. This is as far as the novice came.

Figure 5.6 The carbon structure is now very sharp Figure 5.7 Very small objects could then be identified

When looking closely at the carbon with high magnification and relatively good focus it was possible

to see a very vague gold particle pattern (Figure 5.8). By carefully focusing and adjusting the beam

alignment and astigmatism even further it was possible to start seeing the gold particles more clearly

(Figure 5.9).

44

Figure 5.8 A vague gold pattern can be seen Figure 5.9 Small balls or clusters of gold can now be seen

By taking a picture of this image, an even better quality was achieved due to the long scanning time

of taking a photo. In Figure 5.10 the difference in quality between the image (bottom) and picture

(top) can clearly be seen. The photographing process takes some time and scans the image from the

top to the bottom.

Figure 5.10 The gold particles are now clearly visible. The image is slowly being scanned and the finished picture, thus far in the scanning process, can be seen at the top

These gold particles are several nanometers in length. Compare that with the "small particle" in

Figure 5.7 which is almost 345 nanometer long. Being able to spot these very small gold particles

proved difficult for the novice and to some extent the intermediate. Both the intermediate (~14

minutes before recognizing the gold particles) and expert (~3 minutes) were able to see these gold

particles however.

45

5.3.4 The Results

The results have been summarized according to the 9 different categories mentioned in Chapter

5.3.1 and will be analyzed using the cognitive load theory and representations theory (see Chapter

5.2). Each category will be briefly explained and given examples from the actual interviews followed

by a table containing a summary of all of the interview answers. If the reader wishes to read the

transcriptions more thoroughly they are included in Appendix 2. The quotations from the

transcriptions have been translated to English in this chapter.

5.3.4.1 Planning

Table 5.2 contains the responses from the test persons when asked what their initial plan was and

how they wanted to proceed with the task at hand. Each person got to answer this at the beginning

of every interview and sometimes during later stages as well. The questions were characterized by

asking "Did you know what you wanted to do?" or "Did you have any ideas / thoughts / plans

regarding X?".

Examples

"I thought it might be the easiest if I, if I go the way I'm used to. So take the working distance and

accelerating voltage I'm used to, and then if that would not work I would play around a little bit. But

as far as I remember it worked." - The Intermediate

"My plan was that I, as I always tend to do, that one starts with the astigmatism and such, step for

step. Then I tried to find some good...some good variables which were suitable for achieving some

nice picture and focus." - The Novice

Table 5.2 Planning - What the persons initial thoughts were

Expert Intermediate Novice

Had a clear plan with working distance, acceleration voltage etc

Knew it would be easier than organic samples to get an image since the gold is conductive

Started out with the standard settings

Could refer to a routine check which works the exact same way as in this experiment and is used for checking the instrument's resolution

Used the same settings when working with his own project and was prepared to change some of the parameters

Was going to experiment his way forward in order to determine which settings worked out the best

Knew what to expect from the sample

Expected to see a pattern which would be similar to when looking at platinum coated samples

Expected to see the carbon pattern and small three dimensional particles, similar to those seen in his own project

5.3.4.2 Theoretical Background

Table 5.3 includes all the interview responses regarding their prior theoretical knowledge. It contains

answers with regards to what the participants expected to happen / to see before performing certain

actions.

46

Examples

"In high acceleration voltages this (probe current) does not matter as much. Since the wavelengths,

the error in the wavelengths, the percentage error, is a lot less at high acceleration voltage than at

low acceleration voltages" - The Expert

"Because I'm thinking that if I have gentle beam I'm able to use higher voltage. Gentle beam sort of

removes the voltage, then I can have a lot higher voltage, and I get more focused beams. Because

then one gets more electrons which are hitting the sample so then I might get a better image." - The

Novice

Table 5.3 Theoretical background - What the persons knew regarding the sample and the instrument

Expert Intermediate Novice

A suitable acceleration voltage Gold gives a stronger signal than organic material

Mentions the interaction volume briefly

Acceleration voltages in general SEI gives a stronger signal than LEI

Knowledge regarding the RDC window and that it is possible to use it in order to make the screen update more rapidly in a smaller window

The wavelength percentage error at higher acceleration voltages

How to increase the acceleration voltage in order not to damage the filament

Gentle beam means one is able to run the instrument at higher voltages while still having a low interaction volume

Best achievable resolution You get better three dimensional structure at higher voltages

Higher voltages leads to more electrons hitting the sample which leads to a better image

Effects of different probe currents

The quality between two pictures can be compared by putting the pictures next to each other using a built in function in the SEM

The difference between LEI and SEI

How the sample holder functions and how it affects the image

Ways to adjust the sample holder in order to get better image quality

Which working distance the SEM is calibrated for

47

How to increase the acceleration voltage in order not to damage the filament

When to use beam alignment again after the first time it has been used

A high acceleration voltage charges the sample

5.3.4.3 Theoretical Knowledge Regarding Screen Feedback

Contrary to the theoretical background Table 5.4 takes the participants' reaction into consideration.

Contained here are their answers as to how they interpreted what they saw on the operating screen;

if they knew underlying reasons for the observed phenomena.

Examples

"I realized I do not see anything so I, I thought maybe I must change the conditions. But on the other

hand...I, I was sure I should see something with these conditions and then I thought that OK, maybe I

misunderstood you. I'm looking at the wrong, at the wrong place, on the wrong surface." - The

Intermediate

"When I'm making fine adjustments and I see that they (the particles) are gritty, I often focus where

it's gritty, and then when I'm using fine view I'm able to see what it looks like, and there were some

lines here, I felt there were some charging phenomena which appeared there." - The Expert

Table 5.4 Theoretical knowledge regarding screen feedback ("feedback -> response")

Expert Intermediate Novice

The sample moved a bit and it was slightly blurry -> contaminations in the sample

Was sure he would be able to see something with the current settings but did not -> realized he must be looking at the wrong place

The white part in the picture is the coal

Focusing takes time -> weak signal

Thought that the gold particles would be seen as small clusters near each other but never saw this pattern -> needed to get better focus and magnification

It is possible to determine whether a particle is three-dimensional or "two-dimensional" by looking at how strong the surrounding contrasts are

Was passively looking for instabilities when adjusting focus

The image quality is good when: the structure is clear, the instrument settings are good and there is no astigmatism in the picture

Poor contrasts -> poor focus

The picture started to get blurry -> beam damages at that

The image is stretched out in a

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part direction -> astigmatism

Grittiness and white lines in the picture -> charging phenomenon

Increasing the scan time for the picture to be taken -> creates charging phenomenon

Blurred image -> instabilities -> need to lower electron intensity per unit area

If taking a freeze photo -> risking that the image gets blurry if the sample moves slightly

Using measuring tools to measure the distance between the particles -> gives information regarding resolution quality

Stretched out image -> astigmatism

Some edges are blurry while others are not (in the same window) -> astigmatism

Some areas are white which should be black -> electrons are going through the sample and are being reflected at the bottom of the microscope

5.3.4.4 Experience

Table 5.5 contains prior experiences using an electron microscope or knowledge obtained "from the

field". How used are the participants to working with a SEM and do they have any expectations from

executing the same actions from before?

Examples

"I tried my way onwards, yes, exactly. The thing is that I've used, I'm used to using very low

acceleration voltages and then this (probe current) matters a lot." - The Expert

"Yeah, I was thinking that holes tend to be good. Those are also my experiences that, they're good to

focus on." - The Novice

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Table 5.5 Experience - Previous experience and knowledge that persons said they had gotten from experience

Expert Intermediate Novice

Used to run the SEM at very low acceleration voltages

Used to looking at organic samples

Have only been looking at organic samples for a few weeks, otherwise new to the SEM

Got a routine for focusing (focus -> beam alignment -> stigmators)

The initial SEM settings the person were trying out were the same as in his own project

Was looking at the sample used in this study when initially learning the SEM but had forgotten what the gold structure looked like

The SEI detector gives a two dimensional image which makes it easier to determine the smallest particle

Has looked at samples coated with platinum before and expected to see a similar pattern

Assumed the gold particles would look similar to the particles seen in his own study

A blurry image means it is either out of focus or unstable

Rotates the sample so the grid looks the same as in his own project

Was looking in the grid squares because the person knew he was supposed to look there

There are at least two different measuring tools in the SEM (one more suitable for measuring in a taken picture, the other for real time measuring)

Usually focuses on holes and edges

Was searching for three dimensional structures ("Some sort of dust or something")

Recognized the platinum pattern when the gold was starting to appear

Feels that gentle beam is "good in some way"

Usually uses the RDC window to focus when there is no hole or edge available

Feels that clear contrasts around a particle means it's three dimensional (and not two dimensional like some sort of goo)

Goes in and out of focus and trying to find an intermediate when adjusting focus

The RDC window is used for fine focus adjustments and excessive when doing the rough focusing

Used to looking at bright particles but when he switched from SEI to LEI the colors got inverted which made the person feel it was a bit harder

Feels that his earlier SEM experiences has helped him/her to better know where to look when adjusting focus

Has not been able to play around on his own with the

Usually focuses on holes when adjusting focus

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experiment before

5.3.4.5 Feedback Response

Table 5.6 contains explanations from the participants regarding what they did depending on the

feedback from the screen. This category does not contain a theoretical reasoning for their actions but

rather what they did and what on the operating screen which made them do it.

Examples

"As we noticed in the beginning I found, like, contrasts by the edges there, so then I tried to focus on

the edges because I noticed that a lot of things happened there, when I turned the knob." - The

Novice

"No, I mean, I did not really, yeah, my expectations was that it, it would be like little, clusters again

which sit very close besides each other. I think there I realized that I was not very well in focus. Or the

magniciation was not good enough." - The Intermediate

Table 5.6 Feedback response ("feedback - > response")

Expert Intermediate Novice

Went down in probe current and saw that the image became more blurry -> went up in probe current step by step

The initial image did not resemble expectations -> confusion

Saw a flat surface -> was searching for some three dimensional particle

Looked at the distance between the gold particles -> used this as an indicator of the resolution

Nothing in the picture changed when adjusting focus with currently used SEM settings -> changed area to focus at

Started gentle beam and the image turned blurry -> tried changing different settings such as working distance to see if the image got clearer

The picture started to get blurry when already in focus and nothing else had been changed -> moved to a new area of the sample

Blurry image -> looked for a hole or edge to focus at

Wanted to get a higher resolution than the current -> changed working distance

Gritty picture -> increased the scan time when taking a picture

The gold pattern appears without the person realizing that is the sought pattern -> nothing is done about it

A massive white blur across the entire screen -> adjusted focus very roughly to be able to figure out where he was

A picture being taken started to turn out bad -> canceled the photography early

The gold pattern appears again but this time the person recognizes that it is the pattern to search for -> began adjusting focus to make the pattern clearer

Went in and out of focus -> found and identified the intermediate as being in focus

Took a picture of the gold particles -> used a gray scale to

If no hole or edge was available for adjusting focus -> the RDC

The image was well focused -> immediately looked around the

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make it easier to identify distinct particles in the picture

window was being used sample for some sort of three dimensional particle

The picture is blurry after changing some settings -> adjusted focus

Went in and out of focus -> found and identified the intermediate as being in focus

Found a particle -> adjusted focus, beam alignment and astigmatism -> eventually took a picture but was not satisfied with the focus

Could not see anything in the picture in regular view -> changed to fine view

Blurry image -> looked for a hole or edge to focus at

A method is not working in order to improve focus -> abandon method and try something new

5.3.4.6 Misinterpretations

Table 5.7 contains answers regarding if the participant misunderstood the instructions,

misinterpreted what he saw on the operating screen or could not explain why certain things had

happened during the run.

Examples

"No but, now, yeah, now I understood. Now I understood where the gold is. And I had a completely, I

realized that I had a completely wrong idea of the sample. I thought, I thought that the black dots,

that would be film material but it was holes, wasn't it?" - The Intermediate

"So it might be true actually, that these (the vague gold pattern) are particles and I'm able to see

them back then, but that I don't realize that they are particles." - The Novice

Table 5.7 Misinterpretations

Expert Intermediate Novice

Was to some extent operating the SEM as he would do in lower acceleration voltages even though higher acceleration voltages was being used

Initially thought that the white (the carbon) was gold and that the black (holes) was carbon

Did not know what he could do to improve focus for particles he tried to focus at

During a part of the session a part of the screen turned black then returned again without the person knowing or caring why

Zoomed in at the black area a lot and tried adjusting focus before realizing there was nothing there

Did not realize that the gold particles were actual particles but rather saw them as a pattern in the carbon

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5.3.4.7 External Help

Table 5.8 includes the different external sources which some of the participants used. An external

source would be a source which is not included in the SEM interface.

Table 5.8 External help

Expert Intermediate Novice

None required Asked the researcher twice regarding what in the image was carbon and what was gold

Used a focusing guide on another screen for a bit

Saw the names of the pictures taken by the Intermediate which included detector and acceleration voltages being used and wanted to try those settings for himself/herself

5.3.4.8 Exploration

How much did the test person explore outside of his field of knowledge? The answers shown in Table

5.9 are from when the person did not know what to expect when making adjustments to the settings

or sort of knew what to expect but had to fiddle around a bit before achieving what he sought.

Examples

"Yeah, it's because of this gentle beam, it became totally different. So I tried to, like, find some other

variables. I found, changed some variables to see what would happen." - The Novice

"No, I never use the LEI detector, it was, I thought it's, it's a good, it might be a good idea to check

that. But I never used it before so I did not have any expectations" - The Intermediate

Table 5.9 Exploration

Expert Intermediate Novice

Tried different probe currents in order to get a more coherent beam and better resolution

Changed from SEI to LEI just to see what happened to the image

The initial plan was to try different settings in order to see how the image changed

Did not know what settings to use in LEI so tried several different

Used prior experience but when that did not help completely new methods were tried

Tried settings used in the Intermediate's picture name with the motivation: "I wanted to try these settings since he is more experienced than I am"

53

Was trying to figure out the correlation between working distance and acceleration voltage by doubling one of them and then the other, using the feedback from the image

If a method was fruitful, i.e. gives a better image, it was explored even further

If a method at first did not seem to work, it was abandoned and something else was tried (mainly due to the time limit and he did not want to be stuck on something which might not work)

5.3.4.9 Uncertainty

Table 5.10 contains the different parts where the participants told of uncertainty regarding what

they saw or how to proceed.

Example

"But I think this is just a spike on the grid. That would've just been very weird. No, I thought it was

hard to find particles, I don't even know if this is a particle." - The Novice

Table 5.10 Uncertainty

Expert Intermediate Novice

Not noticeable Uncertain whether to look at the black or at the white

Did not really know what to look for

Lost himself/herself to such a degree the person had no idea where at the grid he was

Did not know if certain things he saw were particles or some sort of spike from the grid

Had a hard time knowing if a particle really looked a certain way and was in focus or if the picture of it was distorted by contaminations

Did not know the limits of the instrument and thus did not dare to experiment all out because he was afraid to

54

damage the SEM

5.4 Interview Analysis

5.4.1 The Expert

The expert had done similar experiments before and knew exactly what to expect and how to do it

which indicates that he possessed suitable schemata. Not only did he identify problems but also

knew different underlying reasons for them and how to solve them accordingly. An example could be

that a particle was out of focus and the reasons could be either 1: The focus of the instrument was

wrong. 2: There were contaminations inside of the microscope which caused this. 3: The electron

beam had charged the sample which made it reflect incoming electrons. Using knowledge such as

this he had several solutions for when encountering problems. This is an example of when a single

image gives different amounts of information depending on the person's prior knowledge.

He used the feedback from the screen to see that his expectations were fulfilled and gave

satisfactory results. Only once did the expert try something which did not give the results he

expected (changing the probe current) but he quickly figured out the reasons for why the screen

changed in the way it did. An important thing to note here is that he almost always knew what the

image would look like before changing a parameter.

There seemed to be very little confusion or surprises for the expert. He could accurately interpret the

screen and had the right schemata to change the image the way he wanted.

5.4.2 The Intermediate

The intermediate had prior knowledge regarding some of the characteristics of the sample (e.g. it

being conductive) even though he had never worked with such a sample before. The schemata being

used were those developed from his own project where he had, for 2-3 years, been looking at

organic samples. He had some experience regarding platinum coated samples and was looking for a

similar pattern. The intermediate thus sort of knew what to expect and what to look for.

The biggest confusion was not how to obtain focus or how to make the image sharp but rather to

interpret the structure he saw. For a very long time he thought that the black spots were carbon and

the white structure was the gold. While believing this the person tried to focus on the black part

(which was a large hole, nothing there). After a while he realized that there was indeed nothing

there, asked me a bit regarding the sample, and moved on to the white part. This is an example of a

graphical constriction in the image since it forced the intermediate to realize that there was

something erroneous in his way of interpreting the picture. He also needed a bit of external help

(asking me about the sample) in order to abandon his hypothesis regarding the black parts being the

area to look at.

The intermediate managed twice to get a good enough focus to be able to see the gold particles. The

first time it appeared he did not realize that he was supposed to look at the white part and did not

see the gold pattern as useful information. Later on, after a brief talk with me, he started to more

carefully study the white parts instead of the black and managed to get a focus which made the gold

pattern visible again. Immediately he recognized the pattern and began focusing on it. Here we see

that more than just the screen feedback was required in order to complete the task. The person had

some experience knowing what platinum coated samples looks like and assumed that the gold

55

pattern would be similar. The person also needed to know where in the image to look to obtain

information useful for progression.

Prior knowledge was required to be able to fully interpret the image and erroneous knowledge

slowed down the task solving progress. This erroneous schema was however corrected into a more

suitable schema thanks to the graphical constrictions of the image as well as consultation with a

person possessing more information.

5.4.3 The Novice

The novice had looked at the same sample during his own practical education of the SEM but said he

had forgotten what the gold particles looked like. The only schemata he had regarding operating the

SEM were from his own project where he had been looking at organic samples. This only contained a

couple of weeks of study however and was not as extensive as the intermediate's experience. The

novice's plan was to use the standard settings and experiment his way forward.

Whereas the expert was looking at the image feedback and confirmed that his expectations were

indeed correct the novice was looking at the feedback in order to check if his manipulation of the

instrument had given satisfactory results. Like I mentioned earlier the reason for why an image is

blurry does not have to be that the instrument is not correctly focused but can be caused by, for

example, contaminations. When the novice looked at the blurry image he tried his best to adjust

focus, align the beams and sort the astigmatism out and when he felt he had done as much as he

could he still was not satisfied with the sharpness of the picture. He explained that he did everything

which is possible and literally said that he had no idea what else to change in order to improve image

quality. Here we see how he interpreted the image correctly (its quality could still be improved) but

lacked the required schemata in order to further improve the quality. We also notice that the image

did not give enough feedback for the novice to be able to adjust accordingly and he most likely

needed a person with the required schemata to teach him what to do.

The novice was very responsive to new feedback and continually altered his settings in order to

obtain the best possible quality. Due to him not knowing what to look for and how large the gold

particles were he assumed their shape would be similar to the particles he analyzed in his own

project. He was able to make the gold particle pattern appear but he did not recognize them as

particles but rather as a pattern in the carbon film and thus ignored it. He was using his knowledge

and experience regarding what a particle should look like and interpreted the feedback on the screen

from those assumptions. This once again shows us a lack in intuitive information from the image,

that prior knowledge regarding what is being seen is required. Had an experienced person helped the

novice to identify problems and interpret the picture the novice would have, without a doubt, been

able to finish the task all the way out.

5.4.4 Comparing the Three

All of the three test persons were frequently using the feedback they got from the imaging screen.

Some information such as sharpness of the picture or astigmatism was easily seen and they all knew

the countermeasures for it. However, some information in the image could be interpreted in several

ways (once again, a blurry image could mean out of focus or contaminations) which is a clear

example of negative graphical constriction. The natural response from the persons were to try and

adjust focus because that is what their schemata told them to do: Blurry image -> adjust focus.

When this did not work for the novice he did not know what else to do and the image did not supply

56

any more specific information. To further improve the image he resorted to just testing new things

such as changing the working distance and hoped it would help.

This study's purpose was to see how the persons would solve a certain task on their own by

interacting with the SEM but would this have been an educational situation the misinterpretations

could have easily been taken care of by having an experienced person nearby who could correct or

expand the test person's schemata during time of confusion. This is what Vygotskij meant by the

proximal zone of development: e.g. the novice was not satisfied with the image quality and felt it

could get better (the image on the screen had provided sufficient enough information for him to

reach that conclusion) but did not know how to proceed any further unless he got some help from an

external source (such as a teacher or a book).

Another hindrance was actually the language. The exact same initial presentation of the task and the

sample was given to each test person yet the intermediate interpreted that information wrongly and

looked at the black part of the sample for a long time while the novice searched for what he was

used to being a particle (which turned out to be 100 times greater in size than the gold particles).

Misunderstandings due to people meaning different things with the same word or just generally

misinterpreting what the person says is an important source of confusion to be aware of. Perhaps the

misunderstandings would have decreased if I had adjusted the wording in the initial presentation

with respect to each test person's individual experience.

Only the intermediate and the expert were able to recognize and photograph the gold particles and

both of them had some sort of expectation of what the particles should look like and how large they

would be. The novice was not sure how the gold particles would appear so he looked for things he

was used to looking at, i.e. particles in the 0,1 - 1 µm range. Both the intermediate and the novice

saw the gold pattern appear but did not care for it since they at that point did not view it as relevant

information due to their expectations and schemata telling them otherwise.

5.4.5 Conclusion

When possessing the correct schemata the representations on the operating screen gave sufficient

enough information to be able to solve the given task. If the person did not have enough knowledge

to be able to interpret the picture the representations often only gave information that something

was wrong but not how to solve that issue.

Linguistic misunderstandings occurred due to the test persons having different experiences of the

words. When I used the word "particle" the novice thought of a particle in the scale 0,1-1 µm while

the actual particles I referred to were only several nanometers in length. When the intermediate

heard me tell his that the gold was sputtered across the carbon and looked at the image he thought

that the white pattern was gold and the black background carbon. Taking a person's previous

experiences into consideration and adjusting the language and explanations accordingly is essential

when explaining a task.

When adjusting the SEM settings the image feedback was almost instantaneous which means that

the image actually is a mix between a static picture and a movie. Rather than having to compare two

pictures at a time the operator could just turn a knob and watch the picture gradually change and

determine if the way it changed was satisfactory or not. The desire for such an immediate response

was clearly seen since all of the test persons chose to always use the less quality but instantly

57

updating "quick view" rather than using the high quality but slow updating "fine view". When

adjusting focus using fine view the operator needs to remember the previous image and compare

that with the image currently on the screen. The computational effort is obviously greater here

rather than looking at a continuously changing picture which updates immediately to one's actions.

Previous experiences were also an important aspect. The two persons who were able to find the gold

particles knew what to look for while the person who did not find them found what he thought to be

a gold particle since that is what he expected. All of the three were capable of getting the focus

which made the gold particles appear but two of them (the intermediate at first and novice

throughout the test) lacked the required schemata to recognize the particles when they appeared.

These people were in the ZPD and the intermediate were able to solve the problem after some

guidance from a peer which possessed the information for further progression (i.e. he asked me

what the black part was and what the white part was). Even during the time of videotaping I noticed

that the novice was able to see the gold but I chose not to say anything just to see if he would be

able to acknowledge it. Had I instead couched him and pointed out that the particles were indeed

there he would have assimilated this new knowledge and been able to take a picture of the gold.

So as a short summary:

The SEM representations gave clear indications of when the image was out of focus but

without proper schemata to interpret what could be the cause the person could not be able

to fully correct the issue.

Adjusting the wording of the task according to the operator's experience is necessary to

avoid misunderstandings.

An immediate response is more preferable over a response which is slow but of higher

quality

Taking the person's previous experience into consideration is necessary to help the person

avoid misinterpreting what he or she sees.

If the representation is not able to supply the user with sufficient information for solving a

task another source of information (such as a teacher) is required.

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59

6 Improving the Physics Experiment

6.1 The Experiment

6.1.1 Background

My thesis required me to get a connection to the Swedish high school which led me to get in touch

with my old school. I met my old physics and math teachers and asked them if they needed any

assistance with improving an already existing experiment, group exercise, lecture or similar. My plan

was to use the knowledge I had gained from my previous pedagogical study where I had used the

SEM. They told me about two different experiments which they liked but where the students showed

signs of obvious confusion in their lab reports. The students were able to solve the experiment tasks

but failed to understand the theoretical concepts essential to each of the labs.

I chose to look at an experiment they use when working with centripetal acceleration. The

instructions are verbal and there is no written material. The lab itself consists of using a bicycle wheel

with a small block loosely attached to one of the axes (see Figure 6.1). The block is able to freely

move up and down and when the students spin the wheel quickly enough the block travels to the

outer rim of the wheel. Using this information the students are supposed to calculate the gravity

constant of the Earth. The students are allowed to ask questions but are encouraged to discuss with

each other first.

Figure 6.1 The experimental equipment for the experiment. The bicycle wheel is at rest and the block is in its initial position near the centre of the wheel

The key to solve this experiment is to study the block when it is at its top position. The only forces

acting on it then are the normal force and the gravitational force which together act as the

centripetal force. When the normal force is close to 0, i.e. when the block is just about to start falling

down due to the angular velocity being too low, the gravitational force is equal to the centripetal

force. This is what the students are supposed to learn.

The students have gotten instructions of what to do, they know that the moment of interest is when

the block is about to fall down and they have also gotten an explanation regarding why this point is

useful to study. They are instructed that during the time and point of interest the gravitational force

equals the centripetal force and they have to solve the following equation.

(1)

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where

(2)

and

(3)

By using (2) and (3) in (1) we arrive at

T is the time for one revolution and r is the radius of the wheel. What the students have to do during

the experiment is find the average angular velocity around the point when Fg = Fc. This is done by

measuring the time from the start and count how many laps the wheel turns (which is easily done by

looking at the position of the block) before the block is about to fall down and then keep taking the

time an equal amount of laps after the block has fallen down.

There is of course a slight difference in the pedagogy depending on if a teacher is teaching adults or

high school students. Furthermore, the pedagogy should take the students’ cultural climate and

previous experience into consideration in order to suit their need as best as possible. I personally feel

that the line between adult and child is very vague and that the high school students are more

related to adults than to children. A discussion regarding the students’ previous experience and how

to take that into consideration will be discussed later in Chapter 6.2.

6.1.2 Common Misinterpretations

The students have been taught about forces in general and the centripetal force and the centripetal

acceleration specifically earlier but that is not to say that all of them have assimilated these models. I

know from experience by being a teacher myself that centripetal force is confusing for many

students. The students have gotten accustomed to working with the gravitational and normal forces

and they are used to those forces often being included in physical models.

In my opinion there are two ways to understand the centripetal model. One way is through working

with the centripetal acceleration and talk about the reasons why this acceleration exists (more about

this in Chapter 6.2.2.1) . The other way is by understanding that the centripetal force is not a unique

force like the gravitational force (more about this in Chapter 6.2.2.2). For now I will focus on

misinterpretations regarding the centripetal force since that is where many problems occur.

The gravitational force has a clear origin, it "comes" from the Earth pulling the object towards it. The

normal force is a bit harder for students to understand (Minstrell, 1982) but once they figure it out

they see it as the force which holds and object back from motion (e.g. a table exerts a normal force

on a book which lies on the table). Other forces such as friction, drag and pull also tends to be rather

intuitive from what I have noticed. One problem some students had was that they did not know how

to "add" this new centripetal force into their model. Their previous schemata might tell them that if a

new force is introduced you simply put an arrow in the picture somewhere like in the case with

gravity, normal force etc. Chandralekha (2009) noticed the same tendencies where some students

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interpreted the centripetal force as a "new physical force of nature rather than a component of the

net force" (Chandralekha).

Examples of student solutions I have seen have included the normal force (not always), the

gravitational force (very often) and the centripetal force, all summed together. Their reasoning has

been that the gravitational force is always there and then there is the centripetal force to pull the

object to the middle of the circle, from here on they did not know how to proceed (see Figure 6.2).

The examples are both from the lab as well as from different textbook tasks which students asked for

help with.

Figure 6.2 One student solution which did not allow for any further progress

One of the tougher, first obstacles in the physics course is understanding that objects are at rest if all

the forces have a net sum of zero (Minstrell). A lot of work is sometimes required (depending on the

class) in order for the students to grasp this concept and plenty of textbook tasks are centered

around this scenario. In the case of centripetal force, some students have felt it intuitive to interpret

the phenomenon as the force acting outwards (see Figure 6.3), that something is dragging the object

away from the middle (i.e. the fictive centrifugal force). When they combine this feeling with their

previous schemata telling them that the forces usually net 0 they come up with the model presented

in Figure 6.3.

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Figure 6.3 Another student solution which gives a correct answer but interprets the centripetal force theory incorrectly

The conclusion, that FN + Fg = Fc , is correct since they are only calculating using scalars and not

vectors. Often it is possible to get an answer which is the same as the textbook's answer which gives

the student an indication that this is indeed correct, even though the theoretical modeling is wrong.

This, I feel, is a very common mistake and the hardest one to spot since, often, the feedback the

students first get is the answer page at the back of the textbook to check whether or not they got a

similar answer.

My personal belief is that a lot of the misinterpretations come from earlier schemata and poor

assimilation. I feel that the students who are struggling with the concept of centripetal acceleration

are those who see the centripetal acceleration as a new, independent force.

6.2 Improvements

6.2.1 Comparison With the SEM Results

There are two huge differences between the SEM and the high school lab. It is not as much as the

subject but rather the means of interaction. When a person is using the SEM he can try different

approaches in order to gain focus and receive feedback from the screen indicating the success of the

attempt. Accommodation and assimilation is actively taking place when a novice is experimenting

with different SEM settings, noticing what is fruitful and what is not. There is a clear learning

situation in the interaction between the user and the instrument. There were times when the SEM

representations did not supply sufficient information for further progress but it at least indicated

that something still was wrong.

Compare this kind of interaction to that of the high school lab. The things the students looked at (the

angular velocity of the wheel) was not at all connected to their knowledge regarding forces. The lab

really taught the students how to measure a difficult thing such as the angular velocity by using the

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well known velocity formula (v = s/t). Whether or not the students understood the abstract model of

forces was irrelevant for their success of completing the experiment. The interaction with the wheel

did not clarify the force model either since no force arrows (i.e. the representation of a force the

students are used to) were ever visible. The main issue with this lab, in its current state, is that the

theory regarding centripetal acceleration is completely disconnected with what the students are

doing during the lab.

Erroneous knowledge regarding the centripetal force is not corrected through the interaction of the

bicycle wheel in the experiment but rather through discussion and guidance by an experienced peer

(the teacher for example). There are different ways to attend to this issue which I will talk about.

6.2.2 Clarifying the Theory Before the Experiment

Two of the things I concluded in my interview analysis were that it is important to:

Adjust the wording of the task according to the operator's experience in order to avoid

misunderstandings.

Take the person's previous experience into consideration in order to help the person avoid

misinterpreting what he or she sees.

These points are directly applicable here with "the operator" referring to the students in the

experiment. Before starting the lab the concept regarding the centripetal acceleration and

centripetal force has to be thoroughly cleared up. The students also need to know and understand

why the top position of the wheel is the most important position during the lab. Following I will

discuss two ways to talk and work with the centripetal model. Either by looking at centripetal

acceleration in an isolated way or transition into talking about centripetal force as well.

6.2.2.1 Working With Accelerations

Like I previously mentioned some students have a hard time when the centripetal force is introduced

because they do not know how to fit this new force into their current model. Where is it added?

Where will it point? What invisible, magic force is pulling the object towards the center of the

trajectory?

Instead of talking about a force constantly acting on the object an approach by just looking at the

acceleration can be taken instead. The students should know (if they do not this concept should be

introduced) that an object's speed changes if it is accelerating unless the acceleration is

perpendicular to the velocity. If the acceleration constantly is perpendicular to the object this means

the object will follow a circular path with a constant velocity.

This inward acceleration, without yet talking about its origin, is called the centripetal acceleration.

Simply put it is defined as the acceleration which keeps an object in a circular motion. From Newton's

second law of motions we know that the acceleration of an object with a certain mass is related to a

net force acting on the object. Instead of introducing the centripetal force as a new concept we can

now just talk about the centripetal acceleration and the net forces. By multiplying the centripetal

acceleration with the object's mass we are then allowed to compare this product with the sum of all

of the forces.

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6.2.2.2 Working With Forces

If the teacher wishes the students to learn about the centripetal force concept this part can either be

a natural transition from working with the acceleration or the teacher can start here at once,

ignoring the centripetal acceleration introduction. I will talk more about my own opinion regarding

this matter later on.

When the centripetal force is introduced the first step would be to give each student a picture of the

wheel when it is spinning and the block in different positions. The students would first only draw the

centripetal force in the picture and afterwards a discussion regarding where this force comes from

would arise. At this point it should become clear what sort of understanding the students have of the

centripetal force. The teacher can easily tell from the pictures and the discussion if the students

believe it is a unique force or if they have confused it with the centrifugal force. It is crucial that the

students are grasping the concept that the centripetal force, in this specific case, is the sum of the

reactionary (normal force of the wheel rim + normal force of the wheel axis) and gravitational force.

6.2.3 Solving the Experiment Task

Depending on if the teacher wants to talk about centripetal acceleration or centripetal force the

experiment procedure will differentiate slightly. In the first part the students should be tasked to

draw out the forces acting on the object. These forces can either be written out alone (in the case of

talking only about centripetal acceleration) or as components of the centripetal force.

Figure 6.4 Three different block positions showing the gravitational and reactionary forces as well as their relation to the centripetal acceleration

Figure 6.5 Three different block positions showing the gravitational and reactionary forces as components of the centripetal force

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This part is to open up the discussion about how to solve the experiment at hand. If the teacher skips

this part there is a risk of only one or a few students realizing what the benefits of measuring the

block at the top position is and those students will give the correct answer. The rest of the class who

have not yet reached this conclusion on their own either understands the reasoning or, in the worst

case, does not understand but accepts it while the experiment keeps on going. By including the part

where every student gets a chance to draw the forces themselves the teacher will have a solid

material to base a discussion on regarding how to measure during the actual lab. It also forces

students to actively participate in the lecture and gives them a chance to think for themselves before

joining the larger discussion.

So far in the theorized lecture the angular velocity of the wheel has been constant but what happens

when the velocity decreases? The discussion should focus around the gravitational force always

being constant thus making the reactionary force decrease when the centripetal force/acceleration

decreases. Another thing worth mentioning is that there is no easy way to measure the reactionary

force which means the students should try to find a position where the reactionary force is

negligible. After further discussion and guidance by the teacher they should reach the conclusion

that the top position is the only place where the only part of the reactionary force which is left is the

normal force from the rim of the wheel. This normal force is decreasing as the angular velocity

decreases. Figure 6.6 and Figure 6.7 shows two different ways of portraying this process.

Figure 6.6 A picture showing the decrement in the normal force as the angular velocity decreases. The bottom part shows the relation between the forces and the centripetal acceleration.

Figure 6.7 A picture showing the decrement in the normal force and how it relates to the decrement of the centripetal force. The bottom part shows the relation between the different forces.

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By including the centripetal force as well as the gravitational and normal force Figure 6.7 gives a clear

connection between the forces. Note that the normal force arrow is on top of the gravitational

force's arrow and not the other way around. This is to increase computational offload since the

decrement of the arrows will appear at the end of the arrow, thus making it clearer that the normal

force decreases while the gravitational force has yet to change since it is constant. A risk with this is

that the graphical constraining is not enough and Figure 6.7 could be interpreted that the normal

force first gets reduced then afterwards the gravitational force. Therefore it might be important to

include a discussion regarding what happens when the required centripetal force is less than the

gravitational force.

Figure 6.8 It is important to discuss what happens when the required centripetal force is less than the gravitational force

If the teacher wishes to refrain from talking about the centripetal force and keep to just talking about

the centripetal acceleration Figure 6.6 would be a more suitable choice . If the students are confident

with the sum of the force equaling the centripetal acceleration times mass Figure 6.6 gives a clear

visualization of the process and the relations between forces and acceleration as well as why the top

position is the position of interest.

6.2.4 Including a Simulator

By using computer software it is possible to create a simulation of the real life situation. What this

simulation can include which the real life experience cannot are the theoretical force arrows. By

seeing the normal force and centripetal force/acceleration change continuously the process of the

wheel spinning is clearly visualized. According to Alty (1991) this kind of representation would be the

most favorable way to explain the experiment. From my own SEM experiment I concluded that

An immediate response is more preferable over a response which is slow but of higher

quality.

By having sliders in the movie of the spinning wheel it would allow for the students to adjust the

different variables such as angular velocity, radius, gravitational constant and mass of the object. This

way it is possible for the students to "accidently" discover the point of interest themselves, just by

fiddling around with the variables. Two other things I mentioned in my analysis conclusion was that

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The SEM representations gave clear indications of when they were out of focus but without

proper schemata to interpret what could be the cause the person could not be able to fully

correct the issue.

If the representation is not able to supply the user with sufficient information for solving a

task another source of information (such as a teacher) is required.

Depending on the students' schemata they might or might not be able to use the information given

in the simulation. They are either not able to progress with the task due to a lack of interpretation

ability or they simply do not have any clues at all what to make of the simulator. As always in a

learning situation it is important to supply something which will help the students evolve in the

proximal zone of development, in this case a teacher. The simulator could be used as a pre-test

before doing the actual measurements on the real life wheel where the students have to explain

their theory using the simulator to the teacher before advancing.

6.2.5 Summary

The biggest issue with the lab is that the theoretical knowledge the teacher wishes the students to

gain from the lab is disconnected from what the students learn during their interaction with the

bicycle wheel in the experiment. In order for the experiment to be meaningful the students must

already possess the correct schemata before attempting the task since the wheel itself will not

assimilate new schemata.

There are different ways to acquire these schemata. One way is to let the class model different

scenarios by using a picture of the wheel and the block in different positions and let them discuss

their models. By having this discussion the students get a chance to correct any erroneous schema

and confirm their correct ones. When the students understand the underlying reasons for why they

are executing the experiment the way they do they are ready to gather the data and finish the lab.

Regarding whether to teach about centripetal force or centripetal acceleration there are both

advantages and disadvantages with the different approaches. Introducing the centripetal force at

once without discussing the acceleration beforehand can be harmful for the students since they

might interpret the new force as a unique force which has some mysterious origin rather than being

composed by other forces. Not mentioning the centripetal force at all however could be harmful for

future occasions since the concept centripetal force is acknowledged amongst people and has been

included in the Swedish national tests for Physics B (the old course in which the centripetal model

was included). My personal choice would be to start with the centripetal acceleration, mention that

the acceleration times the object's mass is equal to a force which is known as the centripetal force

and have a brief discussion regarding that but ultimately continue to work with the centripetal

acceleration.

Another way to create schemata is to let the students work with a simulator before gathering the

data from the wheel. If this simulation includes the force arrows (which are invisible in real life since

they are just a model) a clearer connection between the theoretical knowledge and the real life

experiment can be made. The learning process might be sped up and perceived as more fun by

including bars to adjust the angular velocity of the wheel, the mass of the block and the gravitational

constant.

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These are just a couple of initial ideas and have to be tried in order to be properly evaluated. Due to

a lack of time this will be left for a future project.

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7 Discussion

7.1 The Marine Particles

7.1.1 Comparison With Previous Studies

Results from Leck and Bigg (2005) showed that they were able to find a correspondence between

aggregates found in the surface microlayer and aerosols (from their expedition to the Arctic in 2004).

Comparing the results from this report with those of Leck and Bigg it is possible to see similarities

indicating that many of the particles that I found were most likely all marine gels.

Figure 7.1 is from Leck and Bigg's report showing a patch of thin layer of gel from the SML.

Comparing this with Figure 4.16 we are able to see that they all have very even surfaces and they all

share the same diffuse outlines. Since this report's samples and the ones from Leck and Bigg all come

from the water of the Arctic it is fairly safe to say that the mucus presented in this report is the same

gel Leck and Bigg found. Comparing the gel to the diffuse strings (see Figure 4.14) we see the same

characteristics there as well.

Figure 7.1 A patch of thin layer of gel from a SML sample (From: Leck and Bigg, 2005)

Figure 7.2 Different particles from the air (A, B, C) and from the SML (D) with sizes of A: 38-57nm, B: 35 nm, C: 47 nm, D: ~40nm (From: Leck and Bigg,

2005)

)

Figure 7.3 Different aggregates from the air (A, C, D)

and from the SML (B, E) with sizes of A: 545 nm, B: 95

nm, C: 121 nm, D: 110 nm, E: 186 nm (From Leck and

Bigg, 2005)

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Figure 7.2 shows particles which strongly resemble the nanoparticles showed in Figure 4.15 and

Figure 4.24. According to Leck and Bigg these particles clump up and form the aggregates in Figure

7.3. Similar aggregates can be found in Figure 4.13, Figure 4.17, Figure 4.21, Figure 4.22 and Figure

4.25. What Leck and Bigg also found was that the airborne aggregates and nanoparticles were usually

surrounded by a diffuse material (e.g. Figure 7.2 A). This diffuse material was theorized to be

exopolymer secretions (EPS) produced by microalgae and bacteria from the sea water which these

micro organisms use to concentrate nutrients around themselves. The secretion also protects them

from toxins and cold (Leck and Bigg).

The crystals found (see Figure Figure 4.20) is most likely sea salt. The samples for this report had

been cleaned from sea salts but the cleaning method does not guarantee that they will be 100% salt

free. Judging by how few of these crystals were actually found it is fair to assume that they are the

few who survived the cleaning process.

Leck and Bigg found that there was a size difference of bacteria from water samples and air samples,

where the latter were more narrow and looked more exhausted. Their theory was that bacteria from

the water samples were covered in EPS which protected them from exposure to the vacuum inside of

the SEM while the airborne bacteria did not have this protective EPS layer.

7.1.2 Marine Gels

There is a model of Verdugo's gel production in Figure 3.3. Assuming that the particles in this report

mainly consist of marine gels and aggregates in different sizes it is possible to compare them with

Verdugo's three stages. The diffuse mucus-like gels could be the DOC polymers which have yet to

entwine and mix with calcium to create the nanogels. Figure 7.4 shows two scenarios which might be

in the middle of the assembly/dispersion process

Figure 7.4 To the left we see a diffuse string which seems to be assembling into smaller particles (10k magnification, SSW sample). To the right we see another diffuse string but with larger, more distinct nanogels (10k magnification, SML

sample).

The second process Verdugo mentioned was the annealing of nanoparticles into microgels. In the

small clusters (see Figure 4.17 and Figure 4.25) we see what might be the start of this annealing

process. The nanogels have started to clump up into larger particles which might ultimately form

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particles seen in Figure 4.13 and Figure 4.21. Only 10% of marine polymers actually form the

microgels (Chin et al., 1998) which might be why there were still large amounts of the diffuse mucus-

like gels.

The EPS gels' polymer network collapse if the pH is lowered to 4.5 (Chin et al.) which is a possibility if

the gel is removed from the seawater which has a pH of 8 (Leck & Bigg). Orellana and Verdugo (2003)

showed that when EPS gels are treated with ultraviolet light the polysaccharides are split up and will

not reassemble. Both of these scenarios correspond to what happens when the DOC polymers are

removed from the water by bubble bursting. If these DOC polymers are EPS gels this might explain

why the diffuse mucus was not found in the spray samples.

7.1.3 Particle Patterns

There were two noticeable particle patterns which appeared in the water samples: the halos (Figure

4.18) and the shimmer (Figure 4.19). These areas contain a lot of particles with distinct outlines,

patterns not seen in the spray samples. My own theory is that the patterns have been created by

water (containing all the particles) which later dried up. The halo is most likely created by water

drops and the shimmer could be from larger amounts of water, forming small "rivers" across the

sample surface.

The fragile gel (Figure 4.23) was only found in the spray samples and the reason as to why it was very

sensitive to the electron beam might be the same as the bacteria, i.e. not being covered by

protective EPS.

7.1.4 Particle Size Distribution

The statistical analysis was not able to be finished before the deadline of this report which means

there is no detailed curve depicting the size distribution. It is possible to see that we have particles in

the Aitken mode since many of the nanoparticles and smaller marine gels are in the size range of 10-

100nm. Judging from the samples this mode will be a lot larger in the water samples than in the

spray samples. A reason for this small Aitken mode in the spray samples might be due to smaller

particles not being protected by EPS and thus being more easily disassembled.

The slightly larger gels, those Verdugo called nanogels, are found in all three different samples and

will be contained within the accumulation mode. The frequency of the nanogels found in the water

samples and the spray samples were about the same which means the accumulation mode should

also be fairly similar. Besides the nanogels, crystals were found in the water samples but to such a

small extent their impact on the particle size distribution should be negligible.

I expect the coarse mode to be a lot larger in the spray samples, which were the only samples to

contain what Verdugo referred to as microgels. Where the spray samples were devoid of very small

particles the water samples barely had any particles larger than 1 µm.

7.1.5 Reflections Regarding the Method

The main source of data was from an extensive research using a SEM, taking many hundreds of

pictures of four different ASCOS samples. It appeared later that many of the pictures, especially the

10k ones, were excessive. This excessive work was the result of a misunderstanding in the initial

instructions given. I was told that the 10k pictures would be used for statistical analysis and the 40k

pictures for morphology and topography research while in the end it turned out that the person

doing the statistical analysis needed only 40k pictures.

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My initial thought when I heard that the 10k samples were to be taken for the statistical analysis was

that they wanted a particle per area ratio and to make this as objective as possible I should just take

pictures with an even distance between each. I later found out that they wanted a size distribution

curve and were more interested in how this distribution curve looks like and not so much how

frequent the particles are in the actual samples. These pictures were best taken in a resolution of 40k

magnification. Due to the lack of 40k pictures and excess of 10k pictures more pictures of 40k was

needed to be taken and thus an excessive amount of work had been performed which had been

rather time consuming.

This is not to say that the 10k photos were completely useless as they have provided many high

quality pictures depicting large areas of the different samples. It has not given so much of a

topographical understanding of the smaller particles but rather how the environment has looked for

the different samples. The different samples were easily surveyed and it was possible to get an

overview of the barren "landscape" of the spray samples and the particle rich "galaxies" of the water

samples. Had I initially been given the correct information I would have focused to take more specific

pictures at 10k better portraying these different sample characteristics. I guess the misinformation

was due to misunderstandings and communication errors (which seems to be the reason in 99% of all

cases).

7.2 The Pedagogical Study

7.2.1 Reflections Regarding the Method

The method included both literature study as well as a personally created experiment which I felt,

when combined, gave a solid ground to stand on. The obvious downside with the experiment was the

small amount of participants and this has to be taken into consideration. Three people with very

different backgrounds are not enough to base a theory on but sufficient to give some initial

guidelines.

The SEM experiment itself went well however and the SEM as an instrument was very valuable when

studying the connection between user interaction with its interface and the users' prior knowledge.

More aspects I would have liked to study was to have some individuals of equal skill work together in

pairs of two or three and solve the task to see how that would have changed the problem solving

process. An advantage with having more than one person would have been that they would discuss

with each other (hopefully at least) during the actual execution of the experiment, giving further

information regarding their thought processes and also helping them remember during the

stimulated recall interview.

The interview technique in general felt like a good choice in hindsight. I did an unofficial interview

with the test persons after the interview, briefly asking what they felt about the stimulated recall

method. The responses I got were positive, telling me that it was really helpful seeing what they

actually did instead of trying to remember it all. Due to some weird circumstances (the building

where people worked had to be emergency restored for a few days, forcing people to work from

their homes during that time) it took longer than the recommended two days between experiment

execution and interview. This might have had some impact both on their ability to recall their

thought processes and their gratefulness for having a video tape to recall what they actually did.

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7.2.2 Different Representations

As we saw from the SEM representations, the part which caught the operator's focus for the majority

of the time was the actual image. From previous experience the users already knew where in the UI

to go in order to change operation settings such as acceleration voltage, detector being used etc. This

means that the part which provided information was the image itself. Like I mentioned earlier the

representation was rather a mix between a picture and a movie since the image immediately

changed depending on how the user interacted with it.

Alty proposed that diagrams are good for explaining theories while movies are good to explain

actions and processes. The SEM image fills both these roles as in its static form (not changing the

settings or looking in fine view) it provides information regarding focus, astigmatism, charge effects

and so on. In its dynamic form it shows the process of adjusting focus, correcting astigmatism,

increasing acceleration voltage etc. In a sense it functions in the same way as some games do: static

while not interacting with it and dynamic during interaction. This allows the user to progress in his or

her own pace while also providing feedback regarding the user input (e.g. as adjusting focus).

Alty further mentions that text is good for explaining details and audio can be used to stimulate the

creativity. In educational situations I could definitely see different sorts of "simulators" (I mention

this in Chapter 6.2.4) being incorporated as course material for explaining certain phenomenon.

Simulators can include and visualize things we cannot see in real life, such as magnetic fields, forces

and so on. The simulator could represent a real life scenario including a model (two dimensional or

three dimensional), representations of the theoretical framework such as force arrows, text

explaining the physical formulae being used and how they change and some fitting audio (finding

"fitting" audio will most likely require some research).

Incorporating a simulator into physics discussions should create more interactivity and give

immediate feedback. The benefit of having a simulator is that the boundaries of a given problem is

easily changed. Take the experiment for this report for example. Questions regarding the length of

the wheel axes might arise. What would happen if there is no wall (i.e. the rim of the wheel) at the

end of the axes? What would happen if the axes were infinitely long? What would happen if the

wheel was being spun horizontally rather than vertically? Does this change the model somehow? I

believe incorporating some sort of simulator into the education regardless of subject (at least in

physics) would be very beneficial for schema acquisition. It does not have to be graphically advanced

or super fancy but enough to be able to discuss a problem at hand. The biggest disadvantage here is

obviously the programming knowledge and the time it takes to create suitable and informative

simulators.

7.2.3 Reflections Regarding the Improvements of the Experiment

Due to no two high school classes being the same with respect to skill, knowledge, experience and

interest I feel that it is rather pointless to formulate step-by-step lab instructions. It is important to

tailor the lab to best suit the needs and experiences of the class at hand (Dewey, 2008). I have tried

to take this into consideration and start at the beginning of centripetal acceleration and the concept

in general. This gave me the possibility to control, at least to some extent, the students' prior

experience regarding the centripetal model as they were going to attempt the experiment.

The main problem with the lab, which I have stated several times earlier, is that the theoretical

knowledge is disconnected from the what the experiment actually teaches the students. Students

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with erroneous prior knowledge did not receive any feedback which needed them to assimilate their

"centripetal theory schemata" during the experiment and this erroneous knowledge did not show up

until the lab report, which is the first place an individual student showed his or her interpretation of

the centripetal model (unless the student and the teacher discussed it during class).

By focusing the discussion around the centripetal acceleration rather than force I believe it is possible

to avoid the confusion which typically arises when introducing the centripetal force. The students

expect the centripetal force to be an active force (such as gravitational force, friction and so on) since

that is what their experience tell them to expect. My hopes are that it is possible to circumvent this

problem by exclusively working with the centripetal acceleration and, when multiplied with the mass

of the object which accelerates, compare it with the sum of the forces acting on the object.

A use of pictures, movies or simulators depicting the process will show how the forces, velocity and

acceleration of the object change depending on the position and time. These theoretical models are

not provided by the actual experiment which is why I have been saying that the experiment itself is

not sufficient to assimilate the students' schemata. For the lab to be of any relevance the main focus

should be to figure out how to measure the gravitational constant by using and discussing already

known theories. This discussion should hopefully clear things up and make students assimilate the

correct schemata as long as the discussion is being controlled by an experienced peer (i.e. teacher).

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8 Conclusions

8.1 The Marine Particles

8.1.1 Future Work

There is more work to be done before one is able to draw any proper conclusions from the data

gathered but that is outside the boundaries of this thesis. EDS analyses of the different particles are

necessary in order to determine their chemical compositions, even though it seems fairly likely that

they are different gel aggregates. Before this is done one can only assume that the particles found in

this report are the same kind Leck and Bigg presented.

The statistical analysis needs to be finished before a proper size distribution curve can be presented.

This is on its way however and there is a discussion in Chapter 7.1.4 regarding the different modes.

8.1.2 CCN Coming From the Water

I found no evidence contradicting the theory that CCN are coming from the arctic water via bubble

bursting. There are similarities between the particles from the SSW, SML, Spray samples and the

particles presented by Leck and Bigg (of which some were aerosol samples) which hint that they

might be related to each other. Seeing as the particles from the spray samples were in the typical size

range of a CCN (i.e. around 200 nm) and similar particles were found by Leck and Bigg in their air

samples, it is not completely unlikely that they might be able to act as CCN. So far I am only able to

state that the CCN theory seems feasible and is worth to investigate further.

8.2 The Pedagogical Study

8.2.1 Things to Consider When Creating a High School Experiment

The first thing which needs to be considered, which I am pretty sure every teacher out there is aware

of, is to ask oneself what the point of the experiment is. Is it to pique the students' curiosity when

introducing a new theory? Is it to practice a theory and get some practical experience? Is it a form of

examination where the knowledge and/or skills regarding a certain subject is being tested? There

must be a reason to include the lab, which brings me to the next point.

Does the experiment actually fulfill this role? The experiment's purpose in this report was to enhance

the students' understanding of the centripetal force but what it actually did was train the students in

how to measure angular velocity. It is important to look at what you want the experiment to teach

and what the experiment actually teaches. A good way of determining whether the experiment

served its purpose is to look at the feedback given. It took until the lab reports before it showed that

the bicycle wheel experiment had a design flaw in it.

8.2.2 Educational Experiments

In my opinion, an experiment can be educational in two different ways. It can train the students'

practical skills (such as taking measurements) and/or theoretical skills (such as testing a theory). For a

lab to be successful it comes down to basically one thing: the Experiment needs to give feedback

relevant to the aspect being taught. If the students lack the ability to interpret the feedback correctly

it is necessary to have a source of expertise containing the correct information (i.e. book, teacher)

nearby to allow the students progress in their ZPD.

76

It all comes down to what feedback the students' receive during the experiment. The feedback needs

to be relevant, sufficient and presented in a manner the students are able to comprehend. If the

feedback from the experiment interactions do not fulfill these three points external information

sources (such as a discussion or simulator) could be included or the experiment itself needs to be

adjusted or remade.

77

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matter into polymer gels (1998) Nature 391, page 568-572

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17/8 - 2012

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80

81

Appendix 1 - The Interview Guide The guide used when creating the interview questions

Vad i interfacet är det som hjälper användaren att intuitivt ta sig vidare i sin

problemlösningsprocess? Vilka delar hjälper att minnas träningen som

personen har fått? Vilka delar är överflödiga / förvirrande? Hur påverkar

tidigare erfarenhet personens prestation?

Början vid nytt mål:

Är det ett öppet mål?

Vilka submål finns det?

Har personen gjort detta förut?

Vilken strategi skall användas för att finna dem (means-end, experimentera,

schemata)?

Går det att göra på andra sätt?

Hur vet man när man är klar?

Är det ett tydligt mål?

Har personen gjort detta förut?

Vilken strategi används?

Går det att göra på andra sätt?

Vad är syftet med detta mål?

Problemlösningsprocessen

Representationer

Vet personen exakt var han ska trycka?

Vad händer vid oklarhet?

Föredrar bilder eller text för att orientera sig?

Kan personen beskriva exakt alla steg i förhand för det han ska utföra eller behöver

han sitta själv i programmet och se alla steg (computational offloading).

Hur fokuserad känner sig personen att han måste vara på att klara av uppgiften?

Finns det förvirrande moment i UIn? T.ex. knappar med ikoner som inte motsvarar

deras syfte.

Utförandet

Fanns det några snedsteg?

Var det något som tog längre tid än det borde ha gjort?

Linjärt förfarande eller en fast samlingspunkt som personen ofta går tillbaka till?

Använder sig personen av extern hjälp? (dvs andra personer, anteckningar etc)

Målet uppnått

Avslut

82

Är resultatet samma som personen hade tänkt sig från början?

Hur gör personen om den vill fortsätta arbeta?

Hur gör personen om den vill börja om på något nytt?

Om personen fick ändra något i UIn, vad skulle det då vara? (Flera saker)

83

Appendix 2 - The Interview Transcriptions In the following transcriptions "J" stands for "Jag" (eng: I) and P stands for "Person" (eng: person)

which is the person being interviewed. When there is a parenthesis written within another person's

sentence it is to showcase two people talking simultaneously where the position of the parenthesis

depicts where in the sentence the second person began talking.

The names used in the interviews (when people refer to other persons) are not the persons real

names.

The Expert J: Förstafrågan i alla fall det är...hade du någon plan innan du satte dig ned. Du fick ju reda på vad det

var för typ av...av för prov.

P: Ja... planen som jag hade i det här sammanhanget det var, det var ju det att jag tänkte mig helt

enkelt att man skulle göra samma sak som när man testar helt enkelt upplösning på instrumentet och

då brukar man använda sånt här prov faktiskt. Så att man har då guldpartiklar och som då ligger på

en matris där elektronstrålen går rakt igenom och ner så att säga. Allting är elektriskt ledande och då

ska man använda hög accelerationsspänning och man ska väl ha ännu högre än vad jag hade så det

ska va upp till 30 kilovolt på den där. Men vid 15 kilovolt där ska man kunna ha, där ska man kunna

uppnå bästa upplösning så att säga, en nanometer, det hade jag så att säga i bakhuvudet när jag

tittade på det då.

J: Och det var en typ av en förkunskap som du visste sen innan?

P: Det var en förkunskap som jag visste sen innan, ja, precis om provet så det var inte nåt helt lätt.

Har det varit liksom ett helt okänt prov för mig som stoppas in då kanske då har jag nog fortfarande

gått in på lite lägre accelerationsspänning först och sen om jag fått problem med uppladdningar och

såna saker då hade jag sänkt accelerationsspänningen och jobbat åt det hållet så att säga.

J: Ah, ok. Så, då ska vi se, om vi startar lite grann här i början.

P: Mm.

J: Då ska vi se, jag måste komma ihåg att se vilka tider det är så att jag vet. [...]. Ungefär 03.25 för här

i början så håller du bara på att ställer in fokus ser det ut som. Det ser ut som att (P: Mm) du ställer in

nån typ av skärpa (P: Mm). Eeh, och, det är den här ja. Du håller på att kika runt (P: Mm). Vad är det

du letar efter nu i början när du håller på och gör-

P: Nae jag letar bara efter, eh, jag, det som jag letar efter första det är till exempel att, att först har

jag gjort grovfokuseringen, justeringen så att säga, och nu håller, det jag gör nu här det är att jag

håller på, och justerar för stigmatism (J: Ok). Och vad jag upptäckte när jag satt och körde var att, det

var att provet ändrade sig lite en aning också så att säga och då är det frågan om liksom om det är

provet eller om det är något annat som sker, så jag upptäckte senare att när jag hade kört på hög

förstoring och så fokuserat så blev det blurrigt för att jag hade lite kontamineringar som uppstått (J:

Ok). Provet var inte helt riktigt stabilt heller så att säga.

J: Men hur menar du att den ändrade sig?

84

P: Eh, asså, att den ändrade sig, den, den liksom, nej jag var inte riktigt nöjd med den. Jag ville ha en

stabil bild helt enkelt så att säga, va.

J: Ok, men var det så att det var suddigt eller att det flytt, flyttade på sig när du försökte fokusera,

eller..?

P: Ja, samtidigt som jag försöker gå igenom fokus så försöker jag hitta..hur ska jag säga..ehmm [~6

sekunder tankepaus]. Ja, det som jag gör är det att jag försöker, jag menar, först, det första som jag

gör, det, det är alltid att se till att jag kommer fram så att jag får en bild att få bort stigmatism att få

elektronstrålen schysst och helt OK och det fick jag nog ganska så snart (J: Mm). Sen började jag på

elaborera lite med, om jag inte missminner mig, så ändrade jag på probe current för att jag ville

försöka få en mer koherent stråle och få lite bättre upplösning (J: Ja). Men det innebär att det blir

mer grynighet också så att säga va. Men jag jobbade hela tiden på att kunna få upplösning i mina

punkter, så att säga va (J: Ok). Så jag testade lite med probe current så att säga sen också och det

visade sig nog att på det där instrumentet så spelade det inte så himla stor roll, jag hade kunnat haft

lite högre probe current, det hade gått lika bra också (J: Ok). Jag gick ned till 5 först har jag för mig

men det vart så väldigt grynigt och blurrigt så gick jag upp till 6 och från det steget upp till 7.

J: Mm, så du testade dig fram alltså?

P: Jag testade mig fram, ja, precis, precis. Det är lite så att jag har kört, jag är van att köra väldigt

mycket låga accelerationsspänningar och då spelar det här stor roll. I höga accelerationsspänningar

har inte det här så stor betydelse. Eftersom våglängderna, felet i våglängderna, det procentuella

felet, i våglängsbestämningen, är ju mycket mycket mindre vid hög accelerationsspänning än vid låg

accelerationsspänning (J: Ok). Men jag satt nog kvar vid lågaccelerationstänket när jag höll på där och

justerade fram och tillbaka.

J: Fair enough. Och det här tyckte jag var en ganska intressant bit för du kom fram till, det här är

03.25, till framtida Robin så att han vet var han kollar nånstans. Eh, så redan här, så har du fått fram,

det som jag och Petter uppnådde egentligen som, ja, den bästa bild vi kunde..framnå, liksom du har

redan början ta, det ser ut som fine view (P: Mm) som du kollar på nu (P: Mm). Ehm, men en stund

efter det här så byter du istället till SEI och..ja, ändrar helt och hållet. Du ändrar, spänningen sen-

P: Jaha, från LEI menar du till SEI?

J: Ja, exakt. Jag funderade på, varför...varför var du inte nöjd med den här bilden? Jag tycker den såg

ganska fin ut.

P: Ja, jo, bilden var bra, haha, det håller jag med om så att säga. Eh, sen när jag gick jag in på. när jag

gick ut här, så då var det en sak till. Det är lite strul men den där provhållaren genom att, det är, när

jag kör LEI-detektorn, och kommer ut, där jag inte har koppar som bakgrund (J: Ok, ja). Om jag gör

det, jag tror jag flyttar mig ut här nu och så...sen så..ja, nu har jag gått över till SEI. Ja, men när jag gör

det, så här, alltså...så här, då får jag så att säga en bild från sidan, jag har en tredimensionell bild som

är bra, det, det får jag på LEI-detektorn. Så det har vart ett bra alternativ att ta en sån bild, va (J: Ok,

ja). Går jag sen ut på guldet på kolpartiklarna här, så är det faktiskt så det här, det här detektor, det

här provet har, vad ska jag säga, den här...provhållaren har ett hål rakt igenom och när jag kör LEI

mode här då får jag elektroner dels från ytan härifrån men även de som har gått igenom hela provet.

De som har slagit i botten och kommer som bakgrundsstrålning upp (J: Just det, just det). Det är det

85

som man kallar för sekundär 3-typ och det är den man får med. Därför valde jag då SEI, jag valde

också SEI för att få liksom, öh, se det uppifrån så det, när jag sköt in elektronerna ner då ville jag att,

strålen ned, så ville jag då se att diametern på, att diametern på elektronstrålen så att säga, och då

förväntade jag mig att det skulle bli svart då, mellan de här punkterna som jag har, eller hur jag ska

säga.

J: När du bytte till...SEI-

P: Till SEI, ja just det

J: Du hade alltså en speciell förväntning att det skulle-

P: Jag förväntade mig att jag skulle ge bättre kontrast, att det skulle gå att få bäst kontrast på

guldpartiklarna gick på ut på den här där den hänger över tomma intet så att säga va. Och den tar

bara elektronerna som är på väg tillbaka uppåt, dom, i SEI-mode, så får jag inte in elektronerna som

passerar ner här och träffar resten av instrumentet jag filtrerar bort dom så att säga. Det är lite o.. i

det där är lite, i det här fallet i ett experiment så var det lite, om jag ska säga så, det var inte

genomtänkt kanske. Man kan sätta en liten aluminiumstopper i botten (J: Ok). Då ska man få bra bild

i LEI...och i SEI.

J: Det kunde du ju inte påverka nu.

P: Nej, precis va, så att nu, nu här och nu jobbar jag enbart på förstoringen, avståndet mellan

guldpartiklar, det var bara det jag var ute efter nu. Då får jag en tvådimensionell bild när jag kör SEI.

LEI är mer tredimensionell bild.

J: Ok, och det var..allt var liksom enligt planen antar jag?

P: Ja, planen var helt enkelt att, jojo, jag ska försöka få bästa upplösning så att säga va, därför som du

såg så stannade jag inte där utan jag fortsatte över till det här. Men sen så- åh, förlåt (J: Nej, fortsätt).

Men sen så, sen höll jag mig kvar på samma arbetsavstånd, det här arbetsavståndet då 8 mm och så

och det är det man ska ha som standard när man gör såna här upplösningstester så att säga va (J:

Ok). För att få bättre signal så borde jag sen kanske ha höjt provet högre upp, då hade jag fått in flera

elektroner in till SEI-detektorn och mindre brus i bilden.

J: Men skulle du även ha ändrat working distance då?

P: Då skulle jag ha ändrat working distance, ja, just det, precis. Men nu är det så att instrumentet är

kalibrerat då för just den här höjden (J: Alright) , 8mm.

J: Och än en gång, det är sånt som du vet sen innan.

P: Ja, precis. Det är erfarenhet jag har därifrån så att säga.

J: Alright, ja just den här biten tycker jag också är rätt intressant för det var även en till person som

gjorde det här och det var när du väl här började ändra accelerationsspänningen (P: Mm) men du gör

det i små steg. Jag tänkte, var det något du letade efter i bilden, efter någon speciell kvalitet? Eller

var det så att man tar det i småsteg för att inte skada instrumentet eller nåt?

86

P: Jag går långsamt upp för filamentet, för att inte chocka det. (J: Det är så?) Det är, det är den biten

så att säga. Jag kommer inte ihåg om jag försökte fokusera, om jag försökte fokusera mellan varje,

det kanske jag gjorde, jag är lite osäker på hur jag gjorde. hur jag bar mig åt. Eh. när man går upp till,

jag kollar nog bara lite långsamt, det är bara kolla på det så kollar jag på strålströmmen att den

stabiliserar sig så att säga och att den inte åker allt för mycket.

J: Ok...jag försökte göra någon halvdann inzoomning där (P: Ja, jo precis). Jag var lite osäker på om

man såg alla de här småsiffrorna men det verkar man göra (P: Jo det gör man). Nu får vi se här, runt 6

minuter. Jo, du håller på att åka upp och ned lite där.

P: Ja just det, jag håller på att fokusera och det tar ett litet tag innan jag kommer på fötter beroende

på att signalen är lite för svag egentligen

J: Men det är också en ganska bra sak, brukar du ha nåt typ av mått när du väl fokuserar eller

stigmatiserar, allt det där. Har du något att utgå ifrån eller är det typ erfarenhet och sen ögonmått?

P: Hmmm, nae det är ju erfarenhet. Jag har ju det här rutinmässiga systemet att man, att man, låt se

nu , att provet ger fokus, man sätter in i viss fokushöjd så flyttar jag in provet dit och sen gör man

beam alignment och det är sån där rutin som jag kör.

J: Mm, Ok. Jag tänker just själva kvaliteten och skärpan och sånt.

P: A, det kollar jag ju så att säga hela tiden när jag kör sen så vill jag att det ska vara stabilt framförallt

va.

J: Alright. Men, a, just det. Jag kanske är lite seg, men (P: Nej, förlåt, nämen-) just det här med, du

använder ordet stabilt ganska ofta. Vad exakt betyder det om du skulle lägga det som en kvalitet. Om

ett prov är stabilt eller instabilt.

P: Ja, asså det är om det är antingen att det rör sig, att man liksom ser att om man inte rör

instrumentet, rör någon kontroll, så ser jag att bilden förändras (J: Ok). Då kallar jag det för instabilt,

och det kan asså vara det att det är nån kontaminering som kommer ovanpå, nån uppladdning som

inte försvinner ordentligt bortifrån den eller såna saker va.

J: Alright, men då är jag med, då, då-

P: Så jag tror jag slutade sen med att jag liksom fokuserade så bra jag kunde då så såg jag att det vart

det sen så flyttade jag bort så tog jag bilden på ett annat område som låg i samma höjd så att säga.

J: Och varför tog du på ett annat område?

P: Därför att jag tyckte liksom att det, det grötade ihop sig litegrann (J: Ok). Jag fick strålskador så att

säga.

[Efter det här fram till slutet av första filmen pratar vi om att han svartlade en stor del av skärmen

förutom en specifik ruta i mitten som han redan hade uppe sen innan. Det var inte med avsikt att

svartlägga allt utan det hände lite av en slump/misstag. Inget som, enligt han själv, påverkade

honom.]

LJUDFIL #2

87

J: Och då fortsätter vi med Mats, och det som jag tänkte fråga då var, jag ska bara ställa ned datorn

igen, (P: Det var nummer 9 sa du, eller 8). Ja exakt, 8.45 ungefär Men det som jag tycker är lite

intressant här det är att du fokuserar och sen tar du align reset sen fokuserar du och sen tar du align

reset och du håller på så några gånger fram och tillbaka.

P: Ja det är ju dumt, haha.

J: Nej men jag tänkte, var det nåt som du såg då? Som du inte riktigt var nöjd med som du ville göra

om eller var det bara att du jämför mellan olika inställningar?

P: Ehm, jag gör align..reset...och sen så ja..hade jag inte ändrat något annan parameter då?

J: Vi kan kolla, ska se. Jag hade skrivit upp där...45. Vi hoppar tillbaka lite grann. Så ska vi se vad som

händer. [lång paus medan vi tittar på videon]. Här får vi upp bilden igen, då antar jag att du sitter

med...jag här tar du upp förstoringen igen.

P: Ja, jag fixar med förstoringen igen va, på något sätt, jag håller för alltihop, haha, det blev bäst så.

(J: super secret). Men eh (J: Där tryckte du på align reset) .. ja..

J: Så jag bara tänkte, om vi hoppar tillbaka igen (P: men der ser ut som att egentligen.. ) . Det ser ut

som att du letar efter någonting , eller att du blickar över bilden. Det kanske är svårt att komma ihåg

P: Jag kommer faktiskt inte exakt ihåg vad hag gjorde där måste jag nog erkänna (J: Ok). Men det är

väl att jag misstänker att beam alignment...går lite fort ibland också så det är svårt att ha lite koll..där

jag gjorde jag en sån där variant också (J: jag hoppade tillbaka lite grann så det var samma sekvens vi

såg igen). Ok, mm.

J: Jag tror att du gör samma sak igen också, om några minuter, jag är dock inte helt hundra på det.

P: Mm (J: Jag bara tänkt-) Normalt sett är det ju så att man gör beam alignment och sen så kör man

under stigmatism och alltihopa så försöker man fokusera det. Sen, det som man då gör, hur ska jag

säga, att gå tillbaka till beam alignment igen det är bara en kontroll. Jag törs inte säga varför jag

gjorde på det där sättet där (J: Ok): Normalt sett så gör man beam alignment, när man gjort är nöjd

med den, så kan man gå tillbaka och göra en snabbkoll men då brukar man inte trycka align reset (J:

där tryckte du igen, ja). Ja just det, man brukar inte göra det, därför att man vill göra snabbkoll, om

man inte ser att det är nåt som är fel så att säga va.

J: Men jag tänkte om du såg nåt sånt, i bilden, att det var nåt du inte var nöjd med, att du ville göra

om det från början. För det är väl lite det egentligen som align reset innebär liksom?

P: Jo, just det. Man går tillbaka till, till början så att säga. Jag kommer inte riktigt exakt ihåg hur jag

gjorde där faktiskt.

J: Ja, men vi kan hoppa över det. Det är inte så mycket att göra

P: Nej, nej precis den är ju inte riktigt relevant. Jag menar det.. (J: det var nånting som du inte var

nöjd med antar jag?) Ja, nånting som jag inte var nöjd med och sen så var det nog, att jag höll på att

upptäcka att det var, att det förändrades på nåt sätt...ja, ok, nej, jag ska inte säga nåt mer angående

det.

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J: Ok, då är det dags att byta video till del 2. Så här håller du på att fokusera igen (P: Mm), lite fram

och tillbaka, så ska vi se, jag ska fram till...här nånstans. Och det var det som jag hakade upp mig,

eller jag ska inte säga haka upp mig på men reagerade på. Det var den här svarta rutan, men det var

alltså egentligen lite av ett misstag? För här såg vi sen att du byter (P: Mm) jag vet inte om det också

var medvetet eller om det var

P: Det var, jag vet inte varför den var svart, det var förmodligen, gjorde jag inte nåt sånt här, jag

ändrade väl något så att jag har på...svagare intensitet..

J: Vi skulle kunna hoppa tillbaka hela vägen om du vill det.

P: Ah, nae, ok, men det var inget speciellt med den där svarta rutan, det blev helt enkelt så. Jag tror

att det kanske kan vara det att jag ställde om probe current och då blev bilden mörkare och sen så,

så, körde jag ett helscann på den, jag vet inte om jag gjorde det. För orsaken till det svarta där, det är,

det måste bero, jag är säkert på den där automatisk brightness control sen, när jag kör lilla rutan. Så

det var ingen tanke med att få en svart ram runt, den tanken fanns inte.

J: Här bör man kunna ana prov-, nu ligger vi på 02.50 i video 2, och man kan börja ana

guldpartiklarna. Så här nånstans drar du en fine view, så om du ser på det här nu eller kan tänka

tillbaka på var det var du såg, vad är liksom din första tanke när du ser..är det någonting man

behöver förändra eller är det nånting i din plan som behöver förändras?

P: Alltså...när jag håller på att finjustera och ser att de är gryniga, jag fokuserar ofta där det är grynigt,

och sen när jag gör fine view så ser jag hur det ser ut, och det vart just linjer där va, jag tyckte att det

var lite så här..lite uppladdningsfenomen som dök upp där. Det irriterade jag mig lite grann på i

slutet.

J: Mm, för du sitter och kollar på, nu går du ju igen en andra fine view här, så det ser ut i alla fall som

att du sitter och, även att du ändrar lite fokus.

P: Ja, just det. Ja, jag fokuserar igenom det hela och såg att jag låg rätt så att säga, och det gjorde jag

från början. Och sen så drog jag igenom det igen. Så, var det lite på slutet där med stigmatismen, vart

inte helt...Sen ändrar jag, ah just det (J: Ja, du håller på här vid), ja, jo just det. För nu vill jag, nu har

jag fått en bild som är väldigt grynig så nu försöker jag längre tid, på att ta upp en bild, det var det

som var tanken med det här. Så ändrade jag format också så att säga. Men det visade sig också när

jag försökte köra det där sen så insåg jag att, att det vart, det blev uppladdningsproblemet på det här

provet på nåt sätt, för liksom på, det vart avlångt. Jag körde ner en bit så då vart det inte bra så då

avbröt jag det här. Sen gick jag ned till att köra lägre förstoring, för jag höll på att fixa på högsta

förstoring så att säga va, och det..det är inte alltid det är bäst så att säga. För när man har hög

förstoring får man koncentrerad uppladdning, så det är lättare att få uppladdningar också på höga

förstoringar. Det är en balansgång där mellan vilken probe current man har och vilken förstoring man

har.

J: Precis, för det var egentligen nästa sak som jag reagerade på, men det sa du redan nu, att bilden

hann bara komma en pytteliten bit ned (P: Mm) sen bryter du omedelbart (P: Mm, ja du ser den blir

inte bra). Nej, ja, precis.

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P: Sen tar det väldigt lång tid att köra ett sånt här scan. Fungerar det där bra då kan man få en bra

bild med bra upplösning och så.

J: Mm, men exakt vad var det för kvalitet i bilden som indikerade att det här var...dåligt?

P: Neea, asså det var ju, den blev, jag menar det finns inte nån...nae, den var inte bra fokuserad helt

enkelt, eller den blev inte bra fokuserad (J: Ok, så den var typ suddig och sånt?). Ja, den var suddig ja,

det tydde på att det var instabilt på något sätt, jag återkommer till instabiliteten här igen så att säga

va.

J: Så vad var, vad var din plan då liksom? Vad var det du tänkte-

P: Jag tänkte, jag tänkte om bara så här att OK då får jag ta lägre dos per ytenhet och så, och därför

så gick jag tillbaka sen att köra på, en snabbare scan på fotot, så helt enkelt gå ned och köra på lägre

förstoring. För det är också så att jag får mindre uppladdning per ytenhet. Men jag får inte gå ned för

mycket i probecurrent heller för det betyder att det blir mer grynigt.

J: Men är du medveten om alla de här olika, vad ska man säga, inställningarna som råder för tillfället?

Eller är det så att ibland-

P: Ja, här ser du att det blir ränder så här va. Utdragning så här va, och det ska det inte vara, det var

ju former så här på dem va (J: Ah, ja, OK). Det är därför som jag avbryter den där körningen.

J: Så alltså, det är vid 06 ungefär.

P: Då skulle man ha kunnat övergått till en sån här framehistoria istället (J: Frame..?). Alltså att man

kör freeze och adderar ihop dem (J: Ja, just det). Men det är också ett litet problem när man har

rörligthet i det hela, att det rör sig, att det blir otydligt på det sättet.

J: Det blir lite som spökskuggor på bilden.

P: Ja, precis.

J: Nu ska vi se, här är en till funktion som jag inte, som jag faktiskt inte ens vet vad den gör så det

är..för här sitter du och fortsätter tar bilder, här verkar du vara lite..

P: Ja, jag var inte riktigt nöjd med det där, jag tyckte det såg...ja, OK.

J: Nej, nej. Varför var du inte nöjd med den? Jag kan pausa också.

P: Jamen, nej men...nej men.. vi kan fortsätta köra helt enkelt. Jag, nej strunt samma, vi kan fortsätta.

Nästa funktion som du sa?

J: Det är den här gröna rutan (P: Ja, just det). Det vet jag inte ens vad den gör för nåt. Där, vid 8.40.

P: Den mäter avstånden mellan linjerna. Då kan jag liksom gå in och lägga dom, om jag har nåt

objekt, så kan jag lägga det där objektet börjar och slutar så att säga. Så avståndet i X-riktningen är

den funktionen, och siffervärdet det står här nere. Men det skrivs över i det här fallet, det blev bättre

sen när...när man tog bort det. Det är ett sätt att mäta, va. Man kan ju använda mäta i bilden och då

rita ut de där pilarna när bilden är registrerad så att säga va men jag kan också göra på det här sättet

för att mäta avståndet så att säga va.

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J: Ok. Nu ska vi se, jag trooor, ja jag tror att du tog en bild där faktiskt. Men det är också bara ett

annat mätverktyg så du letar bara efter minsta punkterna?

P: Ja, just det. Jag ville se vad det var för upplösning jag hade i bilden, få en uppfattning om bilden.

J: Så vad var det som indikerade, för nu verkar du ganska nöjd med den här kvaliteten? Vad hade

hänt om du inte hade varit nöjd? Vad är det för kvaliteter i bilden i så fall som hade

uppmärksammats?

P: Jag tyckte väl att jag kom liksom inte så mycket längre med prov, det var väl ändå så, det var väl

den känslan jag fick i slutet liksom.

J: Då har du ju ändå suttit och testat runt ett tag så jag antar...har du dom gamla bilderna kvar i

huvudet liksom eller gamla kvaliteten ungefär eller har du något specifikt mått som du brukar utgå

ifrån att jamen nu är det bra kvalitet för nu ser jag att det här och det här syns.

P: Mitt mål är, här letar jag bara efter avståndet för att se upplösningen att det var på samma

upplösning i alla riktningar så att säga va, och hitta de minsta bitarna i bilderna så att säga va (J:

Alright). Jag tycker jag ser det jag ser för att få bästa upplösningen på partiklarna så att säga va.

J: Men du kollar alltså både horisontell och vertikalt.

P: Ja, precis...men det är lite stigmatism kvar där som du ser, haha.

J: Hur ser man det?

P: Det är svårt att säga va men jag tror att den är lite utdragen i den riktingen, för då kan man se

liksom att det är skarpa, dom här kanterna är skarpare va, den där är blurrigare, den här är skarpare.

Men sen är det lokalt från ställe till ställe också så att säga va så det är lite lurigt (J: Så man ser att

den inte är jämnskarp eller?). Ja, jo, precis. Men jag tror nog, jag skulle nog köpa det så att säga va.

Det är ju högsta förstoringen så jag kan mycket väl köpa det här.

J: Här också, varför inverterar du?

P: Det är bara för att få en känsla för gråskalan va. Man kan, man kan...asså det är, vad ska jag säga.

När jag tittar med ögat så är det lätt att se saker och ting men jag brukar använda gråskalan ibland

för att se om jag ser något annorlunda. Jag kan ju mäta...det beror på om, hur...ja.

J: Men föredrar du att mäta svarta avstånd eller att du föredrar...?

P: Jag brukar mäta faktiskt...ja, med partiklarna så gör jag ju sådär förståss just nu va. Men det är nog

liksom bara det, jag tyckte jag såg partiklarna bättre. Partikelstorleken tar jag så här. Men

upplösningen tar jag i den andra kontrasten där jag använde dom här bars, för att se hur långt

avståndet är mellan partiklarna så att säga va.

J: Men hur kommer det sig att du använder det verktyget då och det här verktyget, nu var det ju för

att jag frågade dig i och för sig.

P: Nu är det för att jag har tagit upp bilden så att säga va så då går jag in och mäter så att säga va och,

och...vad ska jag svara på det där.. Det andra verktygen det fungerar i bilden i realtid när jag jobbar

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det här är mer på en sparbild (J: Ok, Ok). Så det här kan man alltså skriva ut sitt resultat. Så jag

använder de här baren dom använder jag i bilden när jag kör, ställer in, och det här använder jag sen

när jag skriver ut en bild som jag vill ha svaren på.

J: Alright, men var det nånstans under resans gång som du kände att nu blev det nåt som inte borde

ha hänt eller fick du några motgångar i din originalplan som gjorde att du var tvungen att ändra dig?

P: Ja, det var lite det här med att det laddade upp. Jag har ju tittat på det här provet tidigare va,

[ohörbart], och då har jag kört på låga accelerationsspänningar va. Den laddade upp lite mer än vad

jag trodde att den skulle göra och det gav mig instabilitet i bilden. Så därför pressar jag mig neråt så

att säga men det finns möjlighet, jag skulle kunna gå vidare med det där, jag tror man skulle kanske

kunna nå resultat om man gick upp till en 30 kilovolt i den stilen va (J: Ok). Men jag är inte riktigt

säker på det va.

J: För nu är det egentligen...ja, typ slut på filmen tror jag (P: Mm). Du kommer att spara den här

snart. Men jag bara tänkte på en annan fråga också, som inte har så mycket med det här att göra

utan det är mest generellt. Om du har, jag antar att när du gör vissa val så har du vissa olika

förväntningar att bilden borde förändras på ett visst sätt (P: Mm). Att när du korrigerar för

astigmatism så bör bilden bli klarare, den ska inte bli utdragen. Vad gör du om...eller om du till

exempel byter till LEI så ska det bli svart där det ska vara svart. Vad gör du om...om du gör de här

förändringarna men det inte sker. Att det bara blir direkt, att du har en förväntning men den uppfylls

inte.

P: Hm, du menar om jag håller på med en justering som inte fungerar för mig så att säga va? (J: Ja,

precis) Jamen då...då jobbar jag helt enkelt vidare. Då hittar jag liksom, vad ska jag säga, jag om det

inte uppfylls då...jag menar om det inte uppfylls de krav som jag försöker uppnå då försöker jag hitta

nåt annat sätt att göra det på så att säga va. Tillslut så hamnar man oftast i en situation att, att det

inte går att få bättre. Då får man bara acceptera och ge upp så att säga va.

J: Och hur ser du när det inte går att få bättre? Är det det att du har experimenterat fram och tillbaka

och ser att det här är nåt slags mittenläge eller...?

P: Ja, nej. Det är när jag tycker att jag har, med dom parametrar som jag tänkt mig, (LJUDFIL #3), inte

blir bättre hur man än gör så att säga va. Sen är det ju så att, ja.

J: Alright, men det är alltså mycket förkunskap som du arbetar utifrån, alltså att det är mycket teori

som du har i bakhuvudet, eller är det mer, vad ska man säga

P: Erfarenhet som jag håller på med som jag hållit på med sen tidigare (J: Det är så?) Ja, det tror jag.

Alltså jag jobbar ju ändå rätt mycket kring teori, jag tänker mig genom interaktionsvolymer och saker

(J: Mm)

J: Men hur mycket anpassar du dig efter den feedback du får från skärmen? Till exempel om du

tänker att, nu ska det vara bra att köra med högre accelerationsspänning men så märker du att det

inte alls funkade.

P: Ja då, i såna fall så om jag ser att det inte funkar med högre accelerationsspänning, då tar jag ju så

att säga och går till lägre accelerationsspänning helt enkelt va.

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J: Så det är inte så att du stenhårt kör på, vad ska man säga, teorin som säger att det borde funka

utan att det ändå är viss...

P: Eller, det är alltid en viss dynamik när man jobbar, det är alltid en viss dynamik. Man kan inte,

teorin är en sak, men man kan aldrig, rent praktiskt så blir det annorlunda, så man måste testa runt

så att säga, i olika riktningar.

J: Finns det, om vi lägger frågan åt andra hållet. Finns det vissa tillfällen där du kör stenhårt på teorin

bara och tänker att nu är det nånting som är skumt i bilden men jag tänker fan inte ge mig för det här

ska funka.

P: Hm, nae. Nej men alltså, jag kör som i teorin så får det väl bli det resultat som är det bästa som jag

kan uppnå på det sättet så att säga va (J: Ok, ja). Så det gör jag ju. Men jag kanske låser in mig på en

viss idé som jag jobbar på och sen så släpper jag idén om jag inser att det inte vart nå bra, så tar jag

nån annan idé och jobbar vidare så att säga va. Det blir lite som trial and error i vissa situationer va.

J: Och bara det här som slutfråga, om det är någonting som du skulle vilja ändra i hur bilden, eller

nånting i UIt eller liksom hur du ser bilden på skärmen, vad skulle det vara? Alltså det kan vara vad

som helst, att den uppdaterar snabbare, eller att det är bättre kontraster eller vad som.

P: Ja, tänker du på instrumentet då så att säga va eller tänker du på..

J: Ja, alltså allt det som du ser på skärmen (P: Här?). Ja. Är det nånting i bilden som skulle kunna

förmedla informationen tydligare till dig, vad som skulle kunna förändras och sånt.

P: Nae, inte direkt. Jag menar när jag ser att det är ju, vad ska jag säga, asså signalen för svag så jag

borde ha haft ett kortare arbetsavstånd så jag får mer signal från själva provet, jag tar in en för liten

del av signalen från provet. Men det är det här att jag höll mig kvar vid teorin, att det skulle vara

8mm arbetsavstånd. Skulle jag lyft upp det skulle jag fått mer signal, helt klart, och bättre 3d-kvalitet.

Men det är det här liksom då att jag, jag låste mig teoretiskt i det här sammanhanget, det var då med

att upplösningen om den ska bestämmas vid 8mm så ska det vara accelerationsspänning på 15

kilovolt. Jag gick upp till 15 men jag kanske skulle ha gått högre, men det var uppladdningarna som

jag inte trodde skulle funka, men det hade gått bättre kanske.

J: Sen var det ju inte jättelång tid heller.

P: Nejmen visst, men jag tyckte jag körde rätt lång tid ändå tycker jag men det beror på hur man ser

på det.

J: Nej, jag trodde du var klar efter tre minuter och tänkte det att ja det här kommer gå skitsnabbt.

P: Haha, så fortsatte jag han irra bort sig, hahaha.

J: Så jag tänkte det att vad skönt det här kommer att bli för min arm, jag blir inte alls trött.

P: Haha, nej just det. Men asså jag kan ju snabbt få fram en bild så den var tredimensionell och så

vidare så att säga men jag var inne på att det skulle vara sekundärdetektorn, så det är lite sån där

teoretisk historia så att säga va.

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J: Men annars då, gick det enligt planen för det mesta eller var det stora förändringar? Om man

tänker så här..

P: Nae, asså stora förändringar var det väl inte egentligen utan jag jobbade nog efter den plan jag

hade när jag började. att jag skulle upp på den accelerationsspänningen och så vidare. Så upptäckte

jag saker och ting, bland annat att det var genomlysning på LEI-detektorn och att det inte var så bra

att använda den i det sammanhanget.

J: Var det någonting du upptäckte eller hade planerat sen innan?

P: Nej, det upptäckte jag då. När jag såg det då så förstod jag att det var det problemet. Visserligen

skulle jag ha kunnat hållt mig på koppargriden i såna fall.

J: Men, då tror jag nog att jag bryter där i så fall. Än en gång, det här var..sjukt värdeligt, faktiskt.

P: Ja, jag vet inte. Vi får se, haha.

The Intermediate J: So the question i want to start just before we start this is, did you have any like, original plan for

when you first started? You got the instructions over what you were supposed to do, and you got

the...like the background of the sample, what it was. So did you have any initial plan or initial thought

when you started like...yeah, did you know what you wanted to do? With the sample. (P: Hmm...) I

could repeat the instructions you got if you want to.

P: Nono, I just have to think. It was...as far as I knew that there is gold on the net, I...do you want me,

do you want me to, to explain it in detail or more...on a higher level? (J: As much as you want) Ok, as

far as I, as soon as I knew that, which material it is on the net I, I got an idea, at least an idea, how to,

how to proceed, even if I, if I never done it before but I, I knew with gold would be pretty, quite easy

to find, to find something. At least more easy than to the samples I'm used to look at.

J: Ok, and why is that? Why would it be easier with gold?

P: Because gold is giving a much stronger signal than my samples, and, yeah.

J: So did you have any plan with which detector you wanted to use, which working distance,

acceleration voltage and such? Did you know if you had any settings you wanted to reach or..?

P: Asså I thought it might be the easiest if I, if I go the way I'm used to. So take the working distance

and accelerating voltage I'm used to, and then if that wouldn't work I would play around a little bit.

But as far as I remember it worked (J: Yeah, rather well, haha). Yes, it worked yes, haha.

J: So let's just see, we're gonna actually start this. And, this is, I'm gonna remove the volume because

there's a lot of background noise actually (P: Yeah). From the ventilation system, and we're mainly

just talking about the guidelines at the very start. So let's see, let's start with...is the light ok for you?

(P: Yeah). Nice, yeah, you're just looking over here. So what were your first initial thoughts when you

first saw this? Because you've never seen a sample like this I guess? (P: Mm.) We're just discussing

about the settings at the moment. So let's see...so I think...yeah at the very start you actually change

detector from LEI to SEI.

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P: Did I? I guess I realized that, that it was in the LEI mode. And, I expected the, the gold on the net to

look in a certain way and when I, when I saw that it...I was confused, because it looked different,

haha. And, I originally thought that the black, that the gold would form dots but not black but (J: Ok)

light dots and, so I was a bit confused and I, I actually didn't know where the gold is (J: Ok). But it

turned out that the gold is on the, the lighter, on the lighter structures (J: Yeah, exactly). And there

was some misunderstanding, and I thought you explained it in a different way but I was a bit

confused, and, but then it became clear somehow. I think I talked to you again and (J: Yeah, you

asked a bit about it). Yeah, and then, then I knew where to go and, where to put the focus on.

J: Ok, we can actually, because that's a very interesting thought. If we just pause here and just look at

this structure. So your initial expectations were that, what...what did you want to see actually? When

you changed from LEI to SEI you had a certain expectation of what the gold should look like. So what

were you hoping to see?

P: Asså...the change from LEI to SEI was because I expected a stronger signal with SEI. With the SEI

detector, and then, I thought I would, I mean that's not very scientific I know hahaha but, it, it, I was

expecting to see clusters of gold like little, yeah, little clusters, separated from each others. We have

before, we have done some, we have coated TEM grids with platinum and then put under the

microscope and it looked completely different. And I was expecting that it would look like the

platinum (J: Alright) but it didn't haha (J: haha) and that confused me haha. And yeah, so.

J: So what was your change of plan when you noticed the new pattern? Did you have any..yeah, what

did you think about it? Did you change your plan somehow?

P: Asså first I thought when, I first tried to find something on the black spots (J: Yeah). And, I realized

I don't see anything so I, I thought maybe I must change the conditions. But on the other hand...I, I

was sure I should see something with these conditions and then I thought that ok, maybe I

misunderstood you. I'm looking at the wrong, at the wrong place, on the wrong surface.

J: Ok, but at least you knew, like from, was it from experience or was it the theoretical knowledge

you had about the microscope that you were using the right settings? Because you said that you

knew you were supposed to see something but you didn't.

P: I think it was both...it was both. I mean if I wouldn't have, if, if I, if I, I mean otherwise I would have

looked with an, at a higher accelerating voltage (J: Ok, yeah). So, but I mean, yeah. My first guess was

I'm looking at the wrong place, and if that would've proven wrong I would, I would have increased

the accelerating voltage (J: Ok) but that was my second choice, but the was not necessary.

J: Ok, so let's just go to here...you did rotate it and I guess...yeah, why did you rotate it just at the

beginning? Is it habit to have it in a certain way?

P: Yeah, I love to have it like that haha.

J: Yah, that's fine. Then you did some focusing and some beam alignment I think (P: Yeah). Are these

standard procedures or do they vary a bit depending on the, on the...sample?

P: Ah, no, it's a standard. I always use, I always take something like and edge or something which is

contrasting very well to focus on.

95

J: Ok, and we can probably skip a bit forward because you're just doing the normal focusing ritual (P:

Yeah.). So if we look at 04.20...yeah, at 04.20, you found the, this spot actually, it kinda looks like a

hole, or well, black spot (P: Mm.). Is there a certain reason you actually looked at that for a very long

time.

P: Yeah, it's very good, you see I'm turning the focusing knob (J: Ah, yeah) and these black holes are

pretty good for focusing.

J: Ok, so did you try to search for a black spot (P: Yeah) like this? (P: Yeah) Ok. It's like, a good

guideline, to get a good focus I guess?

P: Yeah because the contrast is very well, you have the black, the black hole here, and then you have

the, the edges which are much brighter. So it's, I'm always looking for, sort of a hole to focus on.

J: Were you taught that thing or did you learn it by yourself? From experimenting around by yourself.

P: No, I think Martin mentioned it in the beginning, I mean...I think Martin mentioned it in the

beginning. And, I mean you don't always find holes like that but, I do, of course you can use any other

structure which is good enough to focus on. But it's just, a little bit..

J: Ok, but mainly you just want to find something with a good contrast? (P: Yah). Ok. Here you're

looking at the sample again. So if we just look here, you were trying to focus on this, what were your

initial thoughts when you were looking at this because now you have achieved a good beam

alignment and a good focus so it kinda looks like you're searching for something, or...what are your

next steps? From here on.

P: Yeah the idea was now to start look for the structure, if I could find some gold clusters (J: Ok) and,

and I think I was (J: We can actually continue...here) yeah, if you continue. I think I was increasing the

magnification and trying to look a bit closer on one of these black dots to see if I could find

something. And it was....yeah, I mean it was pretty clear that there is nothing, haha.

J: We can actually see...you're asking something here. Let's put the volume up a bit and try to hear

what you say.

[Från videon: P frågar J gällandes vad P ser på skärmen. J tror att de svarta fläckarna är kol och att det

ljusa mönstret är guld. J informerar P om att den ljusa delen är kol.]

J: Here at the end you say "Aha", did you notice something differently?

P: No but, now, yeah, now I understood. Now I understood where the gold is. And I had a completely,

I realized that I had a completely wrong idea of the sample (J: Ok). I thought, I thought that the black

dots, that would be film material (J: Ah, ok, ok) but it was holes, wasn't it? (J: Yeah, exactly). Ok, yeah

(J: So that was absolutely nothing) Ok, haha. And yeah, so, yeah, it was a big...."aha", haha.

J: So now you're trying to achieve focus here I guess? Or are you trying to see something?

P: Yeah, yeah, exactly. And now it, now, I realized it looks, it might look quite similar to the platinum

samples I've, I've seen before.

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J: And now you're actually starting to take a photo (P: Yes). So were you trying to find the same

pattern then? Were you trying to well, like, actively search for it? The platinum pattern, again.

P: No, I mean, I didn't really, yeah, that expectations was it, it would be like little, clusters again

which sit very close (J: Ok) besides each other. I think there I realized that I wasn't very well in focus.

Or the magnification was not good enough.

J: And here you're using the black against the white again for contrast I guess.

P: Yeah, exactly, yeah. And for the focusing.

J: Ok. So yeah, you stopped taking the photo because you saw that the focus was...poor.

P: Yeah, the quality was, yeah, exactly. It was not sharp.

J: Are you looking at the black spot here or are you looking at the white area here? (P: At the edge)

So I think you're just jumping back and forth and trying to focus and such.

P: Yeah, and then I had problems because the sample didn't move.

J: Yeah, I know that problem. It's very annoying. And then when it actually does move it moves you

way too far. (P: Exactly). It's like the most annoying thing with the SEM really actually. So...at 10.20. I

mean, you're looking at this a bit, and you're about to actually increase the [LJUDFIL #2] acceleration

voltage, so you're doing that now I think, up to (P: Oh right. Yes, I did, yeah) yeah you went up to 10

it seems like. [...] Alright you were starting with 5...and then you were actually increasing the voltage,

step by step. So I think you went from 5 to 10, 15 and then to 20 (P: Yeah). So were you looking at

the picture or was there another reason that you did it in smaller steps?

P: No it's, you should not do it in, you should do it, for the instr, it's for the instrument, because of

the instrument you should go higher only in small steps (J: Ok). And I went up with the voltage

because of, I wanted, the higher the voltages the better the three dimensional structure is (J: Alright)

you see on the image.

J: So you already knew which voltage you wanted to reach?

P: Yeah, I thought I go up to 20 or so, 15 or 20.

J: Yeah, you did go up to 20. But you did it in smaller steps just to be nice to the instrument? (P: Yeah,

exactly) Ok. Yeah, so that's actually what you're doing now so we can skip forward a bit. Now you're

at 20.

P: Yeah, now I had to focus again.

J: Yeah, so we can actually skip that part because now you're just looking around a bit. And at...13.10,

yeah now you're just adjusting focus again. At 13.10, around somewhere here. To me it kinda looked

like you were trying to focus at the black part but maybe...were you focusing on the edge again? (P:

Yeah) but, ok.

P: And yeah I think...what did I do? I went up with the magnification and then the edge went out of

the image. But there were still some (J: Ok, so you're actually looking at that part now?) Yeah.

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J: Ok, yeah. So, you're gonna keep on doing this. Just keep on adjusting the focus, adjusting the

sample height (P: Mm). A part which I found quite nice was 14.50 because then you can actually start

to see the gold particle structure. I dunno if you see it here, it's like, very vaguely (P: Mm) and

like..."knotter" (P: Yeah). Did you think about it then or did you not notice it? I mean, it's very very

vague now.

P: Hm, I can't remember. But I thought it's still too...I want to have a better magnification, or better

image (J: So you weren't, you weren't satisfied with the [ohörbart] No.

J: So...we're back here again. And are you still looking at that part over here? (P: Yup) The edge? So

that's actually at 2 minutes, and you're gonna ask about the structure again. If I remember correctly.

P: Haha, did I?

J: That's actually why I'm not sure if you're looking at that part or if you're looking at the black part.

[Från videon: P frågar om Martin har tagit en bild på det svarta och verkar nu förstå att det ljusa är

kolet medan det svarta bara är hålrum]

P: It was still...I did..Jag hade ju inte fattat att. Jag har fattat idag hur det egentligen var. Jag tänkte

hela tiden det var film här.

J: Ah, just det. Ok. Ja, jag tror att när man hade LEI-detektorn på då blir det här som vitt, också. Då

går elektronerna igen om och så reflekteras de (P: Ja, precis. Ja). Så nu tror jag att efter det här så

börjar du kolla ned på det vita, och, får se nu. Som sagt, 03.50 då börjar man kunna se den här

guldstrukturen igen. Så nu håller du på att fokusera igen och håller på. Hoppar fram lite lite grann,

runt 44. Så jag tror att här nånstans börjar man få ganska bra fokus, eller du börjar få ganska bra

fokus. (P: Ja, nu, ja) Nu börjar man se ganska bra, var det nånting du såg då också?

P: Asså då tänkte jag att nu har jag, nu har jag strukturen fångad (J: Att nu har du vunnit). Mm,

hahaha.

J: Nu ska vi se...jag nu tar du en bild igen ja. Brukar du använda bilder för fine view också? Eller

brukar du..?

P: Asså jag brukar kolla med fine view om...ja, om det finns nånting

J: Mm, men jag tänker för att typ säkerställa kvaliteten? För du tog en bild förut men sen avbröt du

den när du såg att det var dålig fokus (P: Ja). Nu ska vi se...ja exakt. För här som vi ser så fotar du

partiklarna så var det nån ny tanke då som slog dig eller var det nån ny plan? För nu ska vi se för det

som du gör sen är, ja du korrigerar lite mer sen, fokus och sånt.

P: Ja, och sen byter jag igen till en annan detektor tror jag. Här byter jag till LEI tror jag (J: Ah, precis).

Ja, och det var bara nyfikenhet. Jag tänkte att jag vill veta hur det ser ut (J: Mm) under LEI-detektorn.

J: Jag tror du sparar den här bilden (P: Mm). [...] Så 06.15, då när du ska ställa in fokus, nu använder

du den här rutan. Och den är inte använd tidigare så jag tänkte var det nån speciell anledning till

varför du använder den precis nu eller varför har du inte velat använda den tidigare?

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P: Asså det gör det lite lättare att fokusera. Och, jag vet faktiskt inte varför. Ja, förut använde jag hela

tiden en, kanten, filmkanten av, för, för att fokusera. Och då känner jag att det är ganska lätt att

fokusera men, men här, lurar man sig för med ögonen lurar man sig ganska lätt på, om man har en

image med...mycket poor, asså då känner jag det att det är mycket lättare om jag har den här rutan

(J: Ok) för att fokusera.

J: Ja, för nu kör du ju också med fine view så den uppdateras snabbare om man har en liten ruta.

P: Ja, precis. Och bilden ser lite bättre ut också.

J: Är det någonting speciellt du försöker titta efter när du ställer in astigmatismen och fokus och

sånt? Vad är det för kvaliteter i bilden som du förväntar dig ska ändras?

P: Alltså, jag har en strategi när jag fokuserar. Jag går igenom fokus, ut ur fokus, tittar på båda...in

both directions. And if I, I try to focus, asså, I try to move between out of focus and out of focus and

in between there is, I'm in focus and, so. So I move from out of focus, in focus, out of focus and then

back to in a focus again. So i try to... (J: Find some sort of intermediate between?) to find, asså, try to

look, try to find how it looks like if I'm out of focus and then from that I can judge when I'm in focus.

And it's the same with the... (J : Stigmatism?) stigmatism as well.

J: Alright, so you're trying to find like two extreme points (P: Yeah, exactly) so obviously out of focus

(P: Yeah, yeah, exactly). Ok. Let's just see where we are at..we're at 8.45. Yeah and you're taking a

new photograph here (P: Mm). And was there any particular reason for it? Because, well I guess now

you've just changed the focus, the stigmatism and the beam alignment (P: Mm). I guess you just

wanted to take one for the better quality?

P: Yeah, I just wanted to check if I could improve the quality.

J: Ok, so do you have any guide lines...how do you compare this quality with the, the last one, the last

picture. Can you compare the different qualities in some way or do you have to put the pictures next

to each other and then-

P: Yeah, asså usually I put the, the, you can, you can put the pictures next to each other and compare

them and then you can, yeah then i, then i, throw away the one i don't want to (J: Ok).

J: So soon you're actually gonna, like you said, gonna change to the LEI detector (P: Mm). [...] At

10.20, yeah, here.You've just changed from SEI to LEI. So, did you have any expectations here or?

P: No, I never use the LEi detector, it was, I thought it's, it's a good, it might be a good idea to check

that. But I never used it before so I didn't have any expectations (J: So you were just curious what it

looked like?). Yeah, yeah.

J: So do you know if there are any different settings which you have to take into consideration?

P: No, I did, I did not. I don't know anything (J: Fair enough).

J: Does it look a lot different from LEi to SEI?

P: Yes, of course (J: It kinda looks like the particles are inversed) the particles are inversed, exactly.

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J:Did you expect that or was that new as well? (P: That was new actually.) Ok. So did you feel it was

easier or was it harder than the...well, than it was in the...

P: It was, it was harder because you to have, asså, you have to change in your head, what you are

looking at. I mean usually I look at the brighter particles and now it's the darker stuff.

J: So now you're fiddling around a bit with the beam alignment...oh, alright, you were looking for

another edge I guess.

P: Yeah, I do...exactly, yeah.

J: So you're doing the same steps I guess? (P: Mm). We can actually jump towards the end because

you're just gonna do the normal steps and it's gonna go fairly fine (P: Mm). So at 13.50 I think,

around somewhere here maybe, you're gonna take a picture again, in LEI mode. (P: Hahaha) So what

were your initial thoughts when you first saw the picture? Were you satisfied with it or did you want

to change anything?

P: I, I was checking my own schedule and I thought I would like to play around a little bit more but I

didn't have the time, haha (J: Haha, oh, Ok).

J: And after this you ask if there's any time limit but I say that you can play along for as long as you

like but you said that you had your own schedule so you're actually gonna break after this (P: Ja). So

what made you satisfied with the earlier pictures and this picture? Like, what made you stop, to say

that ok this is fine and I'm satisfied now?

P: Well, I could see a clear structure and I was sure that the settings of the instrument were

optimized so I was in focus and I didn't have any astigmatismus so that the quality of the image was

good and, yeah.

J: Alright. But how do you know that the, you said that the settings were optimal. How, how did you

know that? is that from experience or is there some theory behind it?

P: No it was just from experience. That, yeah, I've done my best to focus. I mean, asså optimized in a

sense that the image is, that I'm in focus and I can see something. Maybe there are conditions that

you can see the clusters even better but with these conditions [LJUDFIL #3] so, pretty Ok.

J: Ok, nice. So yeah, just another question which I've asked everyone that's not really specified to this

video but more in general. Which is, if you have a certain expectation, if you change something like,

you change the detector or you change the working distance you do have some expectation that

something is gonna change in the picture but it doesn't, or it changes in some way that you didn't

expect or didn't have predicted, what do you do?

P: Hmm. I would continue, haha. But I was just thinking, I, I haven't done so much. Asså, in the

beginning when I started with my project I, I looked for the optimal conditions for my sample,

together with Martin. And, and since then I have found that I never do any major changes so at the

moment I'm only looking at these arctic aerosol samples and I always, I have to run them under the

same conditions so that's, and I don't have that much room to play around with the, the settings of

the instrument (J: Ok) because I have to run them all under the same conditions so that I can do my

image analysis and they have to have, have to be, the taken images have to be taken at this, at the

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same conditions and that's why I was so lucky that I had another sample where I could play around a

little bit, haha. I've never really done that, hahaha (J: Haha, yeah, that's nice, haha). Yeah.

J: Alright. Do you rely a lot on experience or do you rely a lot on theory about the instrument, it

might be a bit hard now with your current samples but when you and Martin were first

experimenting around did you rely on the feedback you got from the picture or did you go a lot from

theory? If you kinda understand the question..

P: I think it's always a combination of both, I mean you have to, in principle, know what, what you are

doing when you change your parameters at the instrument but on the other hand you don't really

know what you have in your sample so...I think as soon as we knew that, that we mostly have organic

material in, in...in our samples, that was a starting point to look more in one direction. Asså we

started more to, to change certain settings, we started to look if it would be useful to use gentle

beam. That's where you set a voltage over the sample itself to avoid charging up but that makes only

sense when you, when you know that you have [ohörtbart] contrasting material and it doesn't make

sense if you have salt in the sample, or you don't need it. So it's always, and of course you have to

know what you achieve when, or what you are doing or what you can expect when use, or you

change certain parameters so it's a combination of both I think.

J: Ok. Yeah, that was about it actually so, yeah, thanks a lot!

P: Haha, thank you!

The Novice J: Förstafrågan är då, du fick en förklaring till vad det var du skulle göra, vad det var för typ av prov,

och ja du fick uppgifterna. Hade du någon plan då?

P: Min plan var väl att jag, som jag alltid brukar göra, att man startar med astigmatismen och sånt,

steg för steg bara. Så försöker jag hitta nå bra..bra variabler som passar bra för att få fram nån fin

bild och fokus.

J: Men du hade ingen plan på typ accelerationsspänning, working distance?

P: Nae asså, inget som jag framförde utan jag tänkte att jag skulle köra trial and error. För att se om

jag hittade nåt bra sätt istället för jag visste inte riktigt hur de påverkade varandra. Typ spänningen,

hur påverkar den bilden? Så jag vart liksom tvungen att börja experimentera först för att se hur det

funkar. Så att om jag stegrade spänningen ett visst steg, hur påverkades då bilden tänkte jag, typ så.

J: Och sen ville du då ta feedback från det som du såg då eller?

P: Ja, precis. Asså jag försökte som kombinera dom sen eftersom att man som förändrar en variabel i

taget för att se vad som händer och sen så försöka hitta den bästa symbiosen mellan dom två

variablerna. Den här break even point så att säga.

J: Visste du vad du var ute efter innan du började? Hade du nån koll på vad du kunde förvänta dig av

provet?

P: Nae faktiskt inte, jag har glömt bort riktigt vad som var en partikel utan jag utgick ifrån en partikel

som vi brukar ha på våra analyser och sånt som vi brukar ha på projektarbetet som vi har då. Så jag

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sökte efter vita partiklar i stort sett så när jag kollade på Mats partiklar var de helt annorlunda ju. Så

det var som en annan definition som vi hade tänkte jag.

J: Ok. Så om vi börjar titta på den här.

P: Så det här är från början eller?

J: Ja exakt. Så nu har du suttit och fokuserat lite grann, du har roterat den (P: Precis) lite grann och

håller på fortfarande tror jag, håller på att zooma ut.

P: Men samtidigt asså här vet jag inte riktigt vars, vad det är jag ska titta på heller, vad som är vad (J:

Jaha, Ok). Så jag börjar säkert vid kolet i alla fall och kollar. För det är eftersom på vårt projektarbete

så har, är det själva gridet, det ska vi inte kolla på utan vi ska kolla mellan gridet (J: Mm). Så det är

som gammal experience jag har.

J: Men vad är kolet då? Är det det svart eller det vita

P: Det vita.

J: För just nu har du suttit och tittat på den här ganska länge, är det nåt speciellt du letar efter då? Jag

tror att, ja nu drar du fine view också, så, vad är det du sitter och tänker på?

P: Jag tror att jag försöker hitta nån partikel som sticker ut på nåt sätt. Nånting som liknar typ som,

där uppe så ser du nånting som är vitt (J: Jaha, Ok. Så nånting som är lite) nånting som är lite mer 3D-

aktigt (J: Alright, typ som kornen vi kollar på?): Ja, precis, samma sak tror jag att det är, men nu, nu

ser jag inget så då tänkte jag då zoomar jag väl in lite mer då (J: Alright) för att se om jag hittar

nånting där. För jag har ju som fortfarande fokus där och nu försöker jag hitta fokus med hjälp av ett

hål tror jag för att få nåt bättre...men jag ser att allting är slät fortfarande ju.

J: Mm. Och här letar du fortfarande efter partiklarna då?

P: Mm, precis, nån typ av korn eller nåt sånt. Som särskiljer sig själv.

J: Mm, men vi kan ta och hoppa fram till 04.25 för du håller på att leta runt lite så här och jag antar

att du, som du sa, bara letar efter någon typ av, nånting som sticker ut (P: Precis). Nu ska vi se här,

jag tror att det är här ungefär. Vid 04.20 för ganska snart här så, nu byter du working distance och

sen kommer du att ändra till gentle beam också. Var det något speciellt som triggade det beslutet

eller varför valde du att byta arbetsförhållanden?

P: Till gentle beam? (J: Ja, nu gjorde du det) Nu gjorde jag det, precis. För jag tänkte att gentle

beam...att det är bra på nåt sätt. Om man har, det djupet man har fått fram, som är väldigt bra (J:

djupet?) nämen att du har som ganska snyggt djup som... (J: Interaktionsvolymen?)

interaktionsvolymen, precis. Som gör att du får...att du utsätter för för mycket ström eller nåt sånt (J:

Alright). Eller för mycket, elektroner, elektronbombardemanget har lagom mycket (J: Mm) men det

kanske är den egna hastighet, spänningen eller nåt sånt samtidigt så får man mer intensitet (J:

Alright). Om det makes sense, om du förstår hur jag menar (J: Ja, jo).

J: Här sitter du också och här höll du på ett tag och försökte ställa in fokus.

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P: Mm, det är på grund av den här gentle beamen, det blev helt annorlunda ju. Så jag försökte som

hitta nå andra variabler. Jag hittade, ändrade några variabler för att se vad som händer.

J: Och det är det som du försöker göra nu alltså?

P: Ja, och med fokus, jag tar grovfokus här.

J: För nu (P: Jag kommer inte ihåg hur mycket) för nu byter du tillbaka till en annan working distance.

Så var du inte riktigt nöjd med det som du...ja, du håller på att switcha mellan olika working distances

nu ser det ut som.

P: Jo, jag tror att jag försöker som att gå jättelångt ned kanske, som länge ner. Eller inte som längre

ned utan närmare provet så att säga (J: Ok. Lägre working distance?) Ja, lägre working distance, för

att få bättre upplösning på nåt sätt.

J: Alright. Just det, här har du hoppat ut igen så att du kollar på hela provet i low magnification (P:

Mm). Så...än så länge, hur har du, vad är det du tänker för nåt? Vad är det, följer du planen eller...?

P: Nu vet jag inte riktigt vart jag är faktiskt om jag ska vara ärlig, vad jag gör ens.

J: Alright, nu börjar vi närma oss 06.50. Jag tror att det är lite framöver här som du kommer att få

fram en väldigt suddig bild som du sitter och tittar jättelänge på. Så jag undrar om du sitter och

tänker på nåt speciellt då, vi ska se, vi kommer nog snart till det. Det ska va vid 07.10.

P: Jag bara ska se vilka variabler jag har, jag har 2 kilovolt där uppe fortfarande, SEM har jag, är det

en SEI-detektor också? Working distance är fyra...sex är den uppe på.

J: Och det är den här som du sitter och tittar jättelänge på. Eller ja, länge och länge, typ 10 sekunder i

alla fall. Asså det som du ser från bilden, vad, vad känner du att du borde göra, vad är det den

berättar för dig liksom.

P: Ja det är att jag måste hitta bättre fokus kanske. För nu, asså jag ser ingenting, jag vet ju knappt

om jag är långt ifrån det eller nära provet, asså. Ska jag, ska jag se alla rutor eller ska jag bara se en

ruta? Hur stort avstånd har jag? Jag har ingen aning alls. Så jag försökte bara som skapa en bild i alla

fall ju. Så nu har jag, nu får jag fram nånting i alla fall ju, som en liten ruta i alla fall ju. Sen ser jag att

vart, vart jag är.

J: Så du hade egentligen inte några förväntningar på provet när du försökte ställa in det?

P: Nej, jag ville bara få fram en bild egentligen så att jag förstår vart jag är, för det var såpass oskarpt

ju (J: Ja, det håller jag med om. Det var bara ett jäkla sudd). Eller jag antar att jag tänker så, jag

kommer inte exakt ihåg, för det var ju ett tag som.. (J: Ja, det var ett tag sen) det var ett tag sen så

det känns lite som att jag hoppar mitt in i, i berättelsen. Och nu försöker jag få fram nån fokus här (J:

Mm). Nu går jag som mellan extrempunkter, se var den är som mest oskarp och går tillbaka och,

hittar skärpan.

J: Och det är det som avgör sen vad som är, vad som är bästa bilden eller?

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P: Precis, precis. Det är ju det som vi har hållt med hela tiden ju. Så det är som att man utgår ifrån

tidigare kunskaper som man fått ju, sen så, utvidgar man dom, eller anpassar, men eftersom dom här

inte riktigt funkar så måste man hitta nya baner också.

J: Mm. Och här sitter du och tittar igen med lite fine view (P: Mm.) Asså letar du fortfarande efter

samma saker i provet? Försöker få så det ser skarpt ut och sen letar efter nån partikel?

P: Ja, precis, det är så jag tänker.

J: Alright. Men just nu så kommer det inte hända, just nu så kommer du bara åka runt och fortsätta

fokusera på olika platser, och försöker bara göra så att det blir så bra som möjligt (P: Jo, precis). Men

jag tänker..nu ska vi se, jag tänkte flytta mig till ungefär 13.05. Du hittar nån partikel vid nåt ställe (P:

Mm). Vill du att vi backar tillbaka så att vi ser exakt vart den ligger nånstans eller?

P: Nae, jag tror jag vet ungefär vart den ligger nånstans. Jag får som riktigt inget fokus på den. Så

tillslut så måste jag bestämma mig att jag tar och mäter den bara. För jag vill som att, den blir klar,

att det är en partikel här men jag får aldrig riktigt fokus på den (J: Ok). Jag försökte nu med att

fortsätta, hitta bästa vinklen och sånt men det var svårt, jag förstår inte riktigt vad som är fel. För jag

ser framför mig att det är en partikel här ju (J:Ja), den kan vara en smet också men, det borde vara en

partikel, om man kollar lite mer på kanten här ju, för där ser jag att det är kontraster där. Så nu

försöker jag som att göra den ganska smal egentligen för där upplever jag att det är mest kontraster.

J: Så det är kontrasterna som säger att det borde vara tredimensionellt och inte en smet då eller? (P:

Ja, precis) Eller vad är det som får dig att tycka att det här borde vara en partikel och inte nåt, nåt

kladd som bara ligger där?

P: Jag får som känslan att den är uppböjd för du har dels ganska grått på vänster sida så har du

ganska grått på höger sida också, du har lite mer (J: Ok) variationer i färgerna, så det känns som om

att det är en uppbuktning i alla fall ju (J: Att det blir som konturer typ?). Ja, precis.

J: Nu valde du att lägga till den här rutan istället men just nu så ändrar du fortfarande bara fokus. Så

var det nåt speciellt som triggade dig, det här var första gången som du använder den här hjälprutan,

vid 13.05, så var det nåt speciellt som triggade dig till att använda den? Var det något i bilden som du

inte var nöjd med som gjorde att du valde att gå den där vägen istället?

P: Nae egentligen var det för att jag ville fin, försöka förfina fokus istället. Annars vid

grovinställningarna då behöver man inte ha den. Men ska jag försöka hitta finare fokus så använder

jag den. Och det andra svaret är det att jag inte hittade ingenting, så jag ville ha snabbare upplösning

på bilden, så det var det jag var ute efter egentligen. Så att när jag vrider lite på ratten så vill jag har

en direktförändring (J: Mm) på vad som händer. Och då tänkte jag att fine view brukar ju bidra med

det.

J: Alright, och det är samma här nu också eller?

P: Mm, precis. Att jag ser lite mer vad som händer. Och sen försöka förstå sen också om det verkligen

är en partikel eller om det är en smet.

J: Hur kommer det sig att du zoomade ut såpass mycket då om du ville fokusera på just den

partikeln?

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P: Just där försökte jag kanske hitta ny partikel att fokusera.

J: Ok. Ja, det kanske är det du försöker göra här, om man kollar nere i högra hörnet nu.

P: Precis. Men jag tror att det är bara en tagg egentligen på gridet (J: Ok). Det hade ju bara blivit

jättekonstigt. Nej, jag tyckte det var svårt att hitta partiklar, jag vet inte ens om det här är en partikel.

J: Men känner du att du känner igen partikeln från nåt liknande tillfälle? ÄR det något som du känner

igen sen innan och som du vet att du kan fokusera på?

P: Jo, jag utgår ju ifrån mina tidigare erfarenheter med elektronmikroskop. Så jag tänkte att en

partikel ser ut som en vit fläck. Jag tänkte inte alls som Martin att, dom här bönorna han hade, att

det skulle vara en partikel, jag ser det som ett mönster bara. Så det, jag trodde det var nånting

annorlunda.

J: Nu ska vi se, video 2, och...Ja, här håller du på att försöka fokusera på, du har hittat din

favoritpartikel nu.

P: Mm, och så tar jag fram mått på den också.

J: Jag tror det. Var ser man tiden...där, ungefär vid en minut, här.

[Vi börjar prata i videon vilket resulterar i en liten diskussion angående stimulated recall som teknik

gentemot thinking aloud som teknik. Klippet som vi tittade på var när han hade tagit ännu en bild på

en partikel.]

J: Men vad tänkte du på när du såg den här bilden? Var du nöjd med den?

P: Näe, verkligen inte, det var inge fokus alls på den ju (J: Ok). Men man ser att det var nånting där i

alla fall, sen var det lite tidspress också. Det hade varit skönt om man hade fått lite längre tid.

J: Du hade ju hur lång tid du ville.

P: Jo, men jag var tvungen att fara av (J: Jaha, som en slags egen tidspress). Annars hade jag gärna

velat leka runt mer.

J: Precis här, byter du till LEI istället för SEI. Du har redan gjort det till och med. Jag vet inte om du

kommer ihåg det men varför väljer du att byta detektor?

P: Ska jag vara ärlig så tror jag faktiskt att det stod i, på Marias, prover.

J: Alright, så du ville testa..

P: Ja, jag ville se om det funkade bättre. hon är ju mer erfaren än vad jag är.

[LJUDFIL #2]

J: Hade du nån speciell...några speciella förväntningar i så fall när du bytte eller ville du bara se vad

skillnaden var?

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P: Jag ville bara se vad skillnaden var (J:Ok). Så vet jag att det är en helt annan detektor också så det

blir annorlunda när man tar emot det och samlar upp det (J: Mm). Men jag har för mig också att LEI

är den som är rakt ovanför (J: Mm, det kan det nog vara). Så att det samlar upp...mer

J: Och här byter du working distance, du kommer börja ändra spänningen snart också.

P: Jo precis, här tänkte jag att dubblerar jag spänningen och dubblerar jag working distance, vad

händer då? (P:Ah, så du sitter bara och testar dig fram eller?) Ja, precis. Jag tycker det var en bra, bra

metod egentligen, jag fick fram en bra bild (J: Ok). Så jag tror, skulle jag ha gjort det igen skulle jag ha

börjat med den biten egentligen, dubblera.

J: Men det var ingen teori bakom det utan du ville mest se vad det är som händer om du gör det här?

Eller var det nån teoretisk baktanke du hade, att working distance, om jag ändrar den kommer det

här att hända och om jag ändrar spänningen kommer det här att hända?

P: Jaaea. Jag kommer inte ihåg men jag tror att jag hade nån teori i alla fall, eller inte teori utan tes är

det mer egentligen, en tanke som slog mig bara.

J: Precis, 4 kilovolt och 6 mm.

P: Så det känns ju också som, vad mer kan jag ändra egentligen, förutom working distance och

spänningen?

J: Njae, det är väl inte så mycket mer än så (P: Näe, så jag tänkte att...ja). Jag tror att du, kommer att

ta en bild på den här snart för det ser ut som att du har hittat nån till (P: Jag hitta nån partikel) precis

(P: Absolut). Nån typ av kropp. Ja, nu börjar du mäta också

P: Ja. Där var det mera kontraster i alla fall ju, det var ingen smet.

J: Nu ska vi se...så du kommer ta en bild på den här, jag spolar fram lite så vi inte behöver se när hela

rutan åker ned, det tar ju ett litet tag. Alright, och den här bilden som du får upp nu, vid 07.15, vad

du nöjd med den då när du såg den för första gången för nu har du ju ändå mätt ut, också, partikeln.

Eller var det fortfarande saker som du skulle vilja ändra i den?

P: Du ser, det är ju inge bra fokus alls på den. Tittar jag lite mera så tror jag att jag har stigmatism i

själva bilden.

J: Hur ser du de olika sakerna som du måste ändra? Hur vet du att det både är astigmatism och dålig

fokus?

P: Att det är dålig fokus det är att det är dåliga kontraster tycker jag i bilden, att det är samma, det är

det gråa och mörkgråare. Astigmatismen är att det drar åt ett håll, jag tror att det känns som om att

det drar åt vänster (J: Ok, den är utdragen?). Mm, precis. Så att man ser att det drar åt vänster

jämfört med bilden. Just där, när jag inte är i fokus så känner jag inte av astigmatismen egentligen,

utan när jag är i fokus känner jag av det (J: Asså när du tog..?). När jag tog fotot.

J:Ok, ok. Så det är lite för dålig kvalitet? Lite väl brusigt?

P: Ja, precis, precis. Så jag antar att jag försöker få nåt bättre fokus där det sista minutrarna (J: Mm.).

[ohörtbart] så att jag inte skämmer ut mig själv, det går ju inte att göra.

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J: Haha, är det också lite så här, baktanke, eller i bakhuvudet? (P: Ja) Att det är som en tävling? (P:

Ja). För nu har vi hela, som en fokuseringsprocess här, som du håller på med i unge fär...ja, två

minuter eller nåt sånt. Du gör alla olika vanliga steg, du gör fokusering sen gör du beam alignment

och sen kommer du att göra stigmatisering.

P: Mm, precis. Jag dubbelkollar så att det känns bra och så. Då utgår jag ifrån säkra metoder som jag

använt förut ju.

J: Men är det alltid ögonmått eller har du som nå speciella, som ramar, som du försöker befinna dig

inom och har som extrempunkter som du går via? Eller har du tidigare bilder i huvudet som du vet

ska vara bra, som bra mall.

P: Du sa extrempunkter och ramar. Vad är, vad är skillnaden där? Det är som samma sak.

J: Ja, jo, det är lite samma sak. Extrempunkter var bara en förtydning på ramar.

P: Ja, det är ramarna jag utgår ifrån. Eller, jag kan inte som, jag kan inte utgå ifrån erfarenheter

eftersom partiklar ser alltid olika ut ju. Så jag måste som, titta på varje partikel i taget ju, det blir så

svårt annars. Men jag har ju säkert lärt mig av erfarenheter, av mina erfarenheter, att se nu blir det

mera kontraster nu blir det mindre kontraster, att ta fram mer på ett annat sätt tror jag, än vad jag

gjorde tidigare. (J: Ok) Så att jag ser att här ändras det, här ändras det inte. Så jag hittar lättare, där

det ändras nånting. (J: Mm, ok. Så att du ser förändringarna lättare?) Ja, precis. Asså jag ser, att här

på det vita området ändras det ingenting men här på det svarta ändras det, så då fokuserar jag

blicken på det svarta området istället (J: Ja, ok, ok). För då ser jag hur det ändras mer. Det var nåt jag

inte hade koll på tidigare för då flackade jag med blicken, förstår du ordet flacka (J: Ja, jo). Så att man

som, hoppade med blicken mellan olika ställen medan det hade varit bättre att kanske hitta ett, en

punkt, där det ändras (J: Ok) och sen fokusera på den.

J: Och det känner du att du har bättre koll på nu?

P: Jo, precis. Som vi såg i början så hittade jag som kontraster vid kanten där va, så då försökte jag

fokusera på kanten för jag såg att det hände rätt så mycket där ju, när jag vred på den. Att det

tjockare och mindre och smalare och så.

J: Men så, du satt ett tag och fokuserade på den här partikeln men sen bytte du istället, du hoppade

bort och så hittade du ett hål som du fokuserade om på.

P: Mm, jag tänkte att hål, det brukar vara bra (J: Alright). Det är också mina erfarenheter ifrån att, det

är bra att hitta fokus på.

J: Men var det det att du inte var nöjd med det fokus du hade fått fram tidigare på partikeln eller är

det det att du vet om sen tidigare att det här brukar ge bättre resultat?

P: Näe, jag hade redan tagit ett kort på partikeln så nu försökte jag hitta en ännu mindre partikel (J:

Ok). Så jag tar det som steg för steg. Nu tar jag hjälp av ett hål och försöker som använda en ny

metod för att komma närmare. Sen om jag hade hittat nån partikel nu så hade jag kanske ändrat

spänningen mer och mer, testat nya metoder och sånt tror jag.

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J: Alright, så du letar efter att få bättre resultat (P: Ja) och om det ger bättre resultat så utvidg, vad

heter det, utvecklar du metoden? (P: Ja) Det är kul för jag hade lite fusk eftersom jag både fick kolla

på Martin och Maria innan så jag visste ungefär vad man kunde förvänta sig (P: Mm), och redan här,

jag vet inte om du ser det nu, men det är som knottrigt över hela (P: Mm), hela ytan. Var det något

som du tänkte på då eller?

P: Näe, jag tänkte mest att det var, asså, sudd, nästan (J: Ok). Så jag tänkte, jag tänkte inte alls att det

skulle vara partiklar ens. Jag tror inte att jag var på det djupet ens, eller tror du det? Hade jag såpass

hög förstoring?

J: Det kan vi nog se snart. Du är på...37 000 förstoring just nu ser det ut som.

P: Ja...och hur stor var den där då? Var det mikrometer eller nanometer?

J: Nanometer, fan kan jag hålla still kameran så jag ser. Ja, du ligger nog på runt 30, 40 000 tror jag.

P: Ja, i och för sig, jag tog ju partikeln på ungefär 340 nanometer och Martin var uppe på 3

nanometer eller nåt sånt (J: Ja, nåt sånt). Så då kan det stämma faktiskt, att det är partiklar jag ser

där då, men att jag inte förstår att det är partiklar.

J: Och det var för att du hade en annan uppfattning av vad det var du skulle leta efter?

P: Ja, absolut, jag hade som andra erfarenheter. För jag hade glömt bort från när vi hade

introduktionen med Martin ju, för då fick vi fram partiklar också ju, med Magnus (J: Just det). När han

sa att det här är fyra guldatomer.

J: Just det, exakt. De här klumparna som vi såg.

P: Ja. Jag vet inte, det kan ju vara det att det var dålig utbildning från början. (J: Ja, det i och för sig)

Magnus han visade ju oss fel från början, här ska ni vara och då var det ett hål (J: Ja just det, haha)

som vi kollade på, haha. Det var väldigt svårt, haha. Det kan vara en sån bit också ju, att Maria kanske

har fått bättre utbildning.

J: Och här igen byter du till gentle beam.

P: Näe! Det är inte jag som gör det. Är det jag som gör det?

J: Ja, det är du som gör det.

P: För det sker ju automatiskt också.

J: Där tryckte du ju aktivt

P: Ja, jag gjorde det ja. Ja.

J: Vi kan gå tillbaka och titta.

P: Ja, det vore bra om du gjorde.

J: Nu ska vi se.

P: Ja, det är lite trial and error igen.

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J: Men jag vill bara se så att det verkligen är så för det kan mycket väl vara det att det är automatisk

bara det att jag inte uppfattade det, för den byter till gentle beam low tror jag i alla fall. Det är ganska

snart, nu åker du upp med musen där, och där trycker du på...

P: För jag tänker det att om jag har gentle beam kan jag ha högre spänning ju. Så gentle beam tar

som bort spänning ju, då kan jag har mycket högre spänning ju, och då får jag mer fokuserade strålar

ju. För då får man mer elektroner som träffar provet så då får jag kanske bättre bild.

J: Men nu hade du i alla fall en slags... (P: Tanke) exakt, tanke. Men hade du några förväntningar på

hur bilden skulle se ut? Vad innebär bättre kvalitet?

P: Mer kontraster kanske. Man kan, vara på en högre förstoring (J: Alright). Så man ser typ, mera

klumpar och sånt, fler partiklar kanske (J: Mm).

J: Så själva...resolution, vad heter det på svenska? Den blir bättre? (P: Upplösningen) upplösningen.

P: Ja, absolut. Det är ju det som är målet egentligen, ta fram bättre upplösning.

J: Jo, exakt. Jag tror att vi kan bryta den här videon. Det är en till som är ganska kort bara, för just n

sitter du bara i fine view, jag antar att du letar efter nånting igen (P: Ja, precis), efter nån typ partikel

att titta på.

P: För nu har jag ganska bra kontraster tror jag (J: Ja) om man jämför med föregående.

J: För...det som jag är lite intresserad av, det är, det här har jag frågat alla andra också, det är varför

är dom nöjda när dom är nöjda. Nu sitter du med beam alignment igen ser det ut som va? (P: Mm)

Det här är video 3, jag tror att det började här nånstans, är det likadant igen att du sitter och tittar på

(P: Ett hål) hålet, ja ok (P: Ja).

P: Men är det som så att jag hittar break even point där det är som bäst egentligen, där fokus finns,

så stannar jag kvar där (J: Ok). För jag kan inte göra så mycket mer, jag kan ju, fokus, X och Y ändrar

jag ju, så kan jag kolla på alignment (J: Mm, tror du att du skulle kunna..).Asså när jag hittar ett så bra

fokus som möjligt ju på alla variabler ju det är då jag är nöjd egentligen.

J: Ok, och det är att du kollar på de olika extrempunkterna och kollar på mittenläget?

P: Ja, precis. Hela det där ramarbetet, att man minskar som ramarna (J: Ok) mer och mer. Först från

höger och vänster och sen upp och ner också, så tillslut så hittar jag, bästa fokuset.

J: Ok...och det är då som sagt som du är nöjd?

P: Ja...för jag vet inte hur ska man annars vara nöjd? (P: Jag vet faktiskt inte) För det ska ju ändå se

snyggt ut. Men det kan vara svårt och i och för sig att se på en partikel att om är det verkligen så

partikeln ser ut.

J: Jaha, eller om den är typ förvrängd på något sätt?

P: Ja, förvrängd också det, precis, det tycker jag är svårast egentligen.

J: Mm. Jag tänker på en annan fråga som inte har med det här att göra utan är lite mer generellt. Vad

gör du, för ibland när man gör olika saker, såsom när man ställer in fokus har man förväntningar att

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man ska få bättre fokus, att det ska bli skarpare bild, när man ställer in astigmatismen kanske man

förväntar sig att den ska bli mindre utdragen och sånt, man har ju ändå nå slags förväntningar. När

man ändrar gentle beam som du sa här så vill man ha en bättre bild. Vad gör du om, om du har en

förväntning men sen visar det sig att den inte alls blir uppfylld?

P: Då skippar jag den (J: Du hoppar den helt och hållet?), ja.

J: Hur snabbt ger du upp innan du märker att det här var helt fel?

P: Det gick ganska fort tror jag , asså jag känner att jag har en tidspress på mig på 30 minuter ju (J: Ok,

ja) så jag kan max lägga ned fem minuter ju på det. Och det är nåt som jag har som fått med mig

efter att ha gjort så mycket tentor på KTH ju (J: Ok). Att jag förkastar teori som inte funkar ju (J: Ja,

ok, ok) för man måste gå till ett nytt problem egentligen. Att, att, är man på tenta så löser man

problem, och det här problemet skiter sig, att det är nånstans i slutet så går det bajs och så byter

man problem istället ju (J: Ok). Det är ungefär så jag tänker nu också egentligen ju, att jag, testar en

metod, funkar inte den metoden så byter jag metod ju. Det är inte det att jag försöker fördjupa mig i

den så mycket mera (J: Ok, man ger upp ett sjunkande skepp?), ja precis. Det är, jag det är lite

sjunkande skepp. För det som jag är ute efter, jag försöker hitta som en sammanfattning först ju, på

metoden, men ser jag inte riktigt att sammanfattningen fungerar då fördjupar jag mig inte i den, då

går jag till en annan metod ju (J: Ok, och ser om den är mer effektiv?). Ja, precis. Märker jag att den

är mer effektiv så kan jag fördjupa mig i den, hitta nya variabler och så ju. Jag kände det att när jag

ökade spänning och ökade working distance, den teorin, att det vart väldigt bra resultat, så det skulle

jag alltså ha fortsatt med tror jag, att öka spänningen mera och öka working distance också, jag

tyckte att det funkade bra.

J: Men det var just tiden som du kände var begränsande?

P: Ja, precis (J: Ok). Men det är alltid tiden som begränsar ju (J: Ja, det-) det måste alltid ta slut på nåt

sätt.

J: Det håller jag mä om. Men jag tror att jag är rätt nöjd sådär ändå. För då har vi rett ute lite av det

som du, såg och det som du gjorde.

P: Är du intresserad av hur jag skulle ha gått tillväga egentligen? Om jag hade haft en till dag på mig.

J: Ja, det kan du gärna berätta.

P: För då hade jag gärna läst en bok först eller nåt sånt. Försökt som, tänka igenom lite mer. Vad jag

ändrar på med gentle beam och sånt ju (J: Mm). För om man hade haft det här som jobb så hade jag

gjort så, gått tillväga.

J: Att du läser på om teorin?

P: Läser på om teorin mycket mer istället ju. För då vet jag vad som händer med gentle beam. Det

vart som att nu väcktes det som ett intresse hos mig. Att försöka förstå vad gentle beam är för

nånting och vad det tillför. För när...under vårt projekt har vi haft mer av det här att det här ska du

göra, steg för steg, och inte varför. Nu fick man som testa sin egen metod ju och det är att förstå hur

instrumentet påverkas mycket mer. Det skapas mycket mer intresse att, kunna förstå vad som

händer (J: Mm), än vad jag behöver göra nu ju. För när jag väl får ett ansvar, att, att [LJUDFIL #3] , så

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kan jag förstå teorin för att kunna, för annars blir det här trial and error ju (J: Ja, exakt) men har man

teori så blir det mycket mer vetenskapligt och ingenjörsmässigt bra. Och även effektivt känner jag väl

J: Mm. Jo, man vet precis vilken metod man ska använda

P: Jo, precis. Och det är väl det som Martin är ute efter också kan jag tänka mig också att han vill ha,

mer konstruktivt och att man har olika teorier kan jag tänka mig, att man har vissa arbetsmetoder

som man har utvecklat, erfarenhetsmässigt.

J: Mm, det är egentligen det som Martin säger att han vill att vi ska experimentera runt själva och

hitta vår egen liksom, nisch. Han skolar in oss på det absolut mest basic och sen får vi testa runt själva

liksom och se-

P: Jo men det är ju det som är så svårt också ju, att om vi lägger på för mycket spänning på våra

prover, kommer dom att explodera då? Det är ju det jag inte vet så det är därför jag inte vill

experimentera för mycket. Men jag kände att med det här provet så kunde jag experimentera för att

(J: Det är ett testprov), det är ett testprov och det har varit med om ganska mycket ju (J: Mm). Och

du gav mig också som ett intervall, att mellan här och här kan du ha spänningen (J: Ja, just det). Det

vet jag inte alls hur det fungerar på proverna som vi har nu på projektet.

[Mer diskussion om att våga experimentera med utrustningen generellt. Att man får veta inom vilka

ramar man kan arbeta utan at skada instrumentet]