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www.reading.ac.uk/EMLab
Introduction to the Electron Microscopy Laboratory
Peter Harris
EM Workshops 2017
Who we are
Why electron microscopy?
Specimen preparation for SEM; advanced forms of SEM
EMLab’s facilities
Specimen preparation for TEM
Electron diffraction and X-ray analysis
Becoming an EMLab user
Tour/questions
Electron Microscopy Laboratory
EM Workshops 2017
Electron Microscopy Laboratory
Technical Services
Chemical Analysis Facility
Electron Microscopy Laboratory
EM Workshops 2017
Electron Microscopy Laboratory
Pharmacy: SEM of polyurethane microcapsules
Chemistry: TEM of peptide nanotapes
Food Biosciences: SEM of bacteria
Biological Sciences: SEM of flower from insectivorous plant
Soil Science: SEM of biochar
EM Workshops 2017
Microscopy basics: why electron microscopy?
The highest resolution achievable by a lens is given by the Rayleigh criterion:
αλ
sin.
nd 610=
where d is the resolution, λ is the wavelength of emitted light, and n is the refractive index of the lens and α is the semi-angle subtended by the aperture.
Wavelength of an electron (200 kV): 0.0025 nm.
Highest resolution of transmission electron microscope ~ 0.1 nm. Individual atoms!
Highest resolution of scanning electron microscope ~ 10 nm.
Wavelength of light (blue): ~ 400 nm.
Highest resolution of optical microscope ~ 200 nm.
EM Workshops 2017
Electron Microscopy Laboratory
Scanning electron microscope
Electron gun
Specimen
Electron gun
Condenser lens
Objective lens
Specimen
Projector lens
Fluorescent screen
Electron gun
Digital camera
Condenser lens
Objective lens
Specimen
Projector lens
Fluorescent screen
Electron gun
Digital camera
Transmission electron microscope
Workshop: October 24 Workshop: October 31
EM Workshops 2017
Electron Microscopy Laboratory
EMLab’s scanning electron microscopes
Cambridge S360 High Vac SEM FEI Quanta Environmental SEM
EM Workshops 2017
Electron Microscopy Laboratory
EMLab’s transmission electron microscopes
JEOL 2100Plus TEM/STEM
(installed Feb. 2017)
JEOL 2010 High resolution TEM
EM Workshops 2017
Electron Microscopy Laboratory
Our new transmission electron microscope
JEOL 2100Plus
Capabilities:
Cryo imaging
Tomography
EM Workshops 2017
Looking at “wet” samples in the high vacuum SEM
Animal and plant tissues up to 98% water.
Options for examining these materials in the high vacuum SEM:
Freeze drying
Chemical fixation, critical point drying
Workshop 14 November - specimen preparation for SEM
EM Workshops 2017
Critical point drying
Substitution of water with liquid CO2, which has lower surface tension
Controlled removal of liquid CO2
EM Workshops 2017
Coating SEM specimens
For conventional (high vacuum) SEM, surface must be electrically conducting.
Usually coat with gold, but can also coat withchromium or carbon.
EM Workshops 2017
Sample prepared by fixation & critical point drying
Euphorbia seed. Amal Al Hasan, SBS.
EM Workshops 2017
Cryo-SEM
Workshop: November 7
Potato showing starch grains
EM Workshops 2017
Environmental SEM
Workshop: November 7
Cooled specimen
• Special pumping system allows water vapour to be introduced into chamber.
• Cooled specimen to retain moisture.
• New (backscattered) electron detector.
EM Workshops 2017
Environmental SEM
• Raspberry buds : Hiroyuki Imanishi, Plant Sciences
EM Workshops 2017
Specimen preparation for TEM
Specimens for TEM
3 mm TEM grid
Carbon films
EM Workshops 2017
Specimen preparation for TEM
Inorganic powders – easy!
EM Workshops 2017
TEM in physical science
Platinum/alumina catalyst
Gold nanoparticle
Carbon nanostructures
EM Workshops 2017
TEM in biology
Adenovirus negatively stained with uranyl acetate
Workshop 28 November - Biological specimen preparation for TEM
EM Workshops 2017
Specimen preparation for TEM
Biological TEM – preparing specimens from tissue
Microtome
Fix dehydrate set in resin section deposit on grids stain
EM Workshops 2017
Specimen preparation for TEM
Specimen preparation laboratory
EM Workshops 2017
Specimen preparation for TEM
Microtome
EM Workshops 2017
Biological TEM – thin section
Kidney
TEM in biology
EM Workshops 2017
Cryo-TEM
● Samples suspended in amorphous ice
● No dehydration, fixing or staining: shows samples in their native environment
● Usually carried out using automatic plunge-freezer
FEI Vitrobot
EM Workshops 2017
Cryo-TEM
EM Workshops 2017
Nobel Prize for Chemistry 2017
EM Workshops 2017
Electron tomography
EM Workshops 2017
Electron tomography
Tilt series of carbon nanostructures
Electron tomography
EM Workshops 2017
An electron microscope is not just a microscope
Elemental analysis - determining the composition of materials
Workshop: November 21Diffraction pattern (crystalline C60)
Electron diffraction in the TEM
EM Workshops 2017
X-ray Analysis: Mapping
Workshop: November 21
EM Workshops 2017
Becoming an EMLab user
Sherrie Foo
EM Workshops 2017
Booking system
EM Workshops 2017
Remaining workshops
Date Topic
24 October 2017 Scanning Electron Microscopy
31 October 2017 Transmission Electron Microscopy
7 November 2017 Environmental & Cryo SEM
14 November 2017 Biological specimen preparation for SEM
21 November 2017 X-ray Analysis and Elemental Mapping
28 November 2017 Biological specimen preparation for TEM
EM Workshops 2017
Electron Microscopy Laboratory
Tour/questions
