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Exciting Student Learning with X-rays: Teaching X-ray Analysis Methods

Welcome

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Today’s TopicsOverview of XRD and XRFWhy teach X-ray analysis?X-ray diffraction as a teaching tool in the classroomX-ray crystallography for structure determination in the teaching labX-ray fluorescence spectrometry applications in the fieldSummaryQ & A

Sue ByramBusiness Manager,

Crystallography

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The Complete Frequency Range of Instruments:Today we focus on the X-ray region

What are XRF and XRD?

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X-ray fluorescence (XRF) and X-ray diffraction (XRD) are very powerful techniques that provide information about:• Elemental composition (XRF)• Phase composition (XRD)• Three-dimensional molecular structure (Single Crystal XRD

or Crystallography)

What is X-ray Fluorescence?Elemental Analysis

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X-ray fluorescence (XRF) analysis allows to you to obtain elemental information (Boron - Uranium) from the sample• Elemental analysis is the qualitative or

quantitative determination of the chemical composition of a material.

For example, common table salt is composed of sodium and chlorine, but this familiar chemical compound is also found in the natural mineral known as halite.

• XRF works directly on solid or liquid samples• The analysis is non-destructive and

independent of the chemical bonding. • Dynamic range of the method is from ppm to

%.• Fast and reagent-free.

What is X-ray Diffraction? Why “Phase” Matters

TiO2 as reported on a chemical analysis can appear as different minerals: rutile, anatase, …

Copyright © Fabre MineralsCopyright © Fabre Minerals

What is X-ray Diffraction?The mineral’s “fingerprint” and structure!

Anatase Rutile

The interaction of X-rays with mineral phasesyields typical patternsThese patterns are the “fingerprints“ of the mineralphases present in a sampleThis fingerprint is used to identify and quantifythe mineral phases

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Why Teach X-ray Analysis?

X-ray instruments for diffraction and spectrometry have typically been viewed as powerful tools for “experts” and were viewed as cumbersome and hard to use – like these older XRD, Crystallography and XRF instruments here.

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Why Teach X-ray Analysis?

Now they are even more powerful but also easy to use!

Today’s benchtop XRD and SC-XRD and handheld XRF instruments are safe, simple and give easy-to-interpret results, making them entirely usable at the undergraduate level

And SEEING is BELIEVING – students can now “see” atoms and molecules, exciting them to pursue scientific studies

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Our Panelists

Brian JonesSr. Applications ScientistPowder X-ray DiffractionMadison, WI, USA

Michael RufProduct ManagerSingle Crystal X-ray DiffractionMadison, WI, USA

Bruce KaiserChief ScientistHandheld X-ray FluorescenceKennewick, WA, USA

D2 PHASER SMART X2S

TRACER III-V

X-ray Diffraction as a Teaching Tool in the

Classroom

Brian Jones

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Demands on the College Level Educator

Teach classesResearchFaculty meetingsGrade examsAdvise studentsWrite papersAttend conferencesGrant applications

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Demands on the College Level Educator

Bruker AXS understands these challenges and has created a complete college level course in Powder X-Ray Diffraction:

Practical Powder Diffraction

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What is Practical Powder Diffraction?

A completely prepared college level course on X-ray powder diffraction using our state-of-the-art benchtop powder diffractometer, the D2 PHASERDeveloped in collaboration with Dr. Nattamai Bhuvanesh, Department of Chemistry, at Texas A & M University

12 hours of lecture32 hours of laboratory sessions

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What is Included – Syllabus

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Minutes Hours1. Basic History and possible applications of powder

X-ray diffraction 60 1.02. Concepts 90 1.5

a) Unit Cellb) Symmetry Elementsc) Point Groupd) Space Groupe) Crystal Systemsf) Miller Indices

3. Essential Theory 180 3.0a) Bragg Diffraction and its derivation (30 min)b) Peak positions and factors influencing them (30 min)c) Peak shape functions (30 min)d) Intensities and their contributors (30 min)

i. Scale, Multiplicity, Lorentz Polarization, Absorption,Preferred Orientation, Extinctionii. Structure Factor

e) Systematic Absences (30 min)

What is Included – Syllabus

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What is Included – Slides and Notes

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What is Included – Slides and Notes

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Now let us come to the applications of X-rays. If we have appropriate instrumentation for structure analysis and, if we have our common sugar crystals, of course, we will have to select a proper “single” crystal, and provided with the correct software, by sending X-rays through the crystal and collecting the data, usually for several hours, we can determine its complete structure. By complete structure, I mean, we will get the details about where Carbon, Oxygen and Hydrogen atoms are located in the unit cell, their orientation, bond lengths, and also we can know how much each atom is vibrating in any given direction.

But, one may ask, why we need such information. This kind of structural information is very important, not only to understand the structure of the compound of interest, but it has been shown the crystalline structure of a particular phase directs its properties also. For example in the famous ferroelectrics, BaTiO3, the oxygen atoms form octahedra around the Ti atoms. These octahedra are not symmetric and the Ti atoms are displaced only to about 0.1 Å away from the center of the octahedron. This has been found to be the cause of the electrical properties it shows.

What is Included - Movies

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What is Included – Lab Notes for the Instructor

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What is Included – Powder Material

Bruker supplies all of the powder needed for the labs, including all of the MSDS sheets

Powders provided include: • Al2O3

• BaTiO3

• CeO2

• SiO2

• Si• Silica gel

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What is Included – Lab Sessions

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Laboratory SessionsMaterials should be provided, for additional reading, before the lab sessions to effectively complete the lab sessions on time!

9. Data Analysis a) Basic Analysis (One Lab Session)

i. Identification (EVA) X-ray diffraction as finger printsi.i. Conversion of 2-theta to d and vice versa

(EXCEL and Calculators)i.i.i. Addition of Standards (Si, LaB6, etc)

(Finding Displacements and/or Zero Errors)b) Indexing (one Lab Session)

i. Simple Cubic phase (Table method)i.i. Hexagonal or Tetragonal (Graphical Method)i.i.i. Complex data (TOPAS)

What is Included – Lab Sessions

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Phase Identification and Basic Analysis

Indexing

Quantitative Analysis

Rietveld Analysis

Crystallite Size/Strain Measurement

Data Analysis - Automation (quality control)

Structure Solution

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What is Included – Lab SessionsApplications

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What is Included – Lab SessionsPhase Identification and Basic Analysis

Phase Identification (EVA)Conversion of 2-theta to d-spacingAddition and use of standards (Si, LaB6, etc.)

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What is Included – Lab SessionsIndexing

Simple Cubic phase (Table method)Hexagonal or Tetragonal (Graphical method)Complex data (TOPAS)

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What is Included – Lab SessionsQuantitative Analysis

Reference Intensity Ratio Method (EVA)DQuant (Creating Calibration Curves)

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What is Included – Lab SessionsRietveld Analysis

Simple Systems (CaCo3)Quantitative Analysis - Rietveld MethodAdvanced Quantitative Analysis – sample spiking, degree of crystallinity

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What is Included – Lab SessionsCrystallite Size/Strain analysis

Crystallite Size and Strain Determination of CeO2

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What is Included – Lab SessionsData Analysis - Automation

Automation of phase concentration with DQuantAutomation of crystallite size using TOPAS

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What is Included – Lab SessionsStructure Solution from Powders

Structure Solution of BaTiO3 or CaTiO3 with TOPAS

The D2 PHASERXRD for Everyone - Everywhere

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The D2 PHASERComponents

Bragg-Brentano geometry• Theta / Theta

(sample is always horizontal)• Choice of divergence and

Soller slits

Sample spinner • 1 rpm to 80 rpm

Standard sealed X-ray tube

Choice of detectors• Scintillation counter• LYNXEYE detector

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The D2 PHASER Good Diffraction Practice

Safety assurance• Compliant with the world’s highest statutory requirements

regarding X-ray safety, machine and electrical safety• Two independent fail-safe safety circuits• Maximum X-ray safety with radiation level significantly below

1μSv/h

The D2 PHASERCompact All-in-One Instrument

Internal cooling system –no water supply neededStandard A/C power only• 90-250V (50-60Hz)

Mobile for on-location operationNo alignment necessaryIntegrated PC / monitorHigh-speed Ethernet network interfaceOptionally controlled by external computer

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DIFFRAC.SUITEMEASUREMENT CENTER

Expert-mode1. Real-time measurement display2. Straightforward selection of scan

parameters:• Angular range• Step size• Measurement time

3. Full access to all settings• User management• Database maintenance• Instrument configuration• Service tools

4. Full access to all instrument parameters• Drives• Detector settings• Generator settings

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DIFFRAC.SUITEMEASUREMENT CENTER

Easy-mode1. Real-time measurement display2. Straightforward selection of scan

parameters:• Angular range• Step size• Measurement time

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Practical Powder Diffraction D2 PHASER

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X-ray Crystallography for Structure Determination

in the Lab

Michael Ruf

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3D Structure Determination in Undergraduate Laboratory Courses?

The synthesis of Aspirin is part of many undergraduate organic synthesis laboratories. Typically good quality crystals for single crystal x-ray investigation can be obtained within a few hours from the start of the experiment. Crystallography provides the most unambiguous structural information of all analytical tools.Introduce students to this technique at an early stage and not reserve these tools for cutting edge research.

Aspirin, the most widely used drug in the world.

Synthesis of Aspirin

Acetic anhydride is added to salicylic acid in the presence of a catalyst, phosphoric acidThe mixture is heated to form the acetylsalicylic acid (Aspirin) and acetic acidWater is added to destroy the excess acetic anhydride and cause the product to crystallize

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Crystallization of Aspirin

Aspirin is then re-crystallized from an ethanol water mixtureAspirin forms well defined, colorless, monoclinic crystals which are solvent-free, air stable and easy to manipulate with a preparation needle

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Mounting samples for X-ray analysis

Scooping crystals with Micromounts is easier than mounting with glass fibers UV-curable adhesives gives plenty of time for manipulation and can be cured in secondsPre-aligned pins simplify crystal centering

Point and Shoot in Photography

It is possible to take good quality pictures without any knowledge of

Exposure times F-stopsCMOS or CCD technology Image processingOr even one look at the users manual

VS.

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Point and Shoot in Crystallography?

Should we require that students understand structure factors and comprehend the concept of reciprocal space to be able to determine a structure?

Is it possible to successfully apply this concept to structure determination?

Would this concept lower the barrier to getting students interested in crystallography?

Providing instant gratification?

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X-ray Diffraction

Crystals are solid materials with atoms, molecules, or ions arranged in an orderly repeating pattern extending in all three dimensions X-ray wavelengths are on the order of interatomic distances• Molybdenum radiation: 0.71073 Å• Carbon-carbon single bond: 1.54 Å

X-rays (electromagnetic waves) pass through the crystal as a diffraction grating and the resulting diffraction pattern is recorded on the CCD detector

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Crystallography

Determine position and identity of atoms in crystalsMolecular geometry

Interatomic distancesInteratomic anglesTorsion angles

Extended structureSymmetry relationshipsCrystal packing relationshipsHydrogen bonding schemes

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Molecular Structure

3-Dimensional representation of the moleculeBond lengthsAnglesTorsion angles

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1.3094 (17) Å

1.4851 (20) Å1.3827 (21) Å

Molecular Structure

3-Dimensional representation of the moleculeBond lengthsAnglesTorsion angles

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122.96 (13) °120.69 (12)°

126.62 (14) °

119.54 (14) °

Extended Molecular Structure

Hydrogen bondingPi-Pi interactions

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Extended Molecular Structure

Applying symmetry elementsExtending the structure

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Crystal Structure

Molecule Packing

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Structure Determination for Undergraduate Courses?

Easy to use instrumentation and softwareRobust instrumentation and software!Automation, automation, automationIntelligent “decision making” algorithmsIndependent quality checksCoherent presentation of resultsWhetting the appetite for more!

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SMART X2S

The SMART X2S is a true benchtop system

Can be placed anywhere in your laboratory

Extremely compact, lightweight and completely air-cooledRequires only standard AC power to operate

Draws ten times less power than a conventional diffractometer

Fully enclosed internal radiation shield

No exposure to X-rays possibleNo radiation badges needed

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SMART X2S

No exposure of mechanical components

No risk of users knocking the system out of alignmentNo risk of personal injury by moving parts

Completely automated operation

Sample mounting and alignmentData collectionStructure solutionReport generation

Data compatibility to Bruker’s APEX software suite for crystallography

Kiosk-Style GUI

Providing initial informationFormula

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Kiosk-Style GUI

Providing initial informationCrystal shape

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Kiosk-Style GUI

Acquiring DataData collectionData integration Laue checkContinue data collectionScaling

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Kiosk-Style GUI

Report generationHtml file

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Kiosk-Style GUI

Structure displayChange display modesToggle labelsChange orientationSnapshots

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HTML - ReportExperimental informationJ-mol applet for structure displayTables with structural informationBond lengths and distances

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The Archive CD contains all raw frame data as well as intermediate processing dataThese data are fully compatible with Bruker’s APEX softwareAPEX is a fully integrated intuitive crystallographic software suite used by expert crystallographers around the worldAPEX leads the user through the complete crystallographic experiment

Various levels of automationEasy to use for novicesAll “bells and whistles” for the expert crystallographer

Advanced Processing – Teaching From Data

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Easy to use instrumentation makes it feasible to introduce single crystal diffraction in teaching classesInstruments are low maintenance and do not require much infrastructureInstruments are small and mobile, robust and stable

Conclusion

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X-ray Fluorescence Spectrometry Applications

in the Field

Bruce Kaiser

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Instant Elemental Analysis AnywhereAddictive and Relevant!

Today’s industry relies on compositional analysis and quality control of products using elemental analysis techniques (AAS, ICP and XRF)Graduates need to be introduced to the concept of “spectroscopic” methods covering qualitative and quantitative analysis XRF now offers an affordable way to teach analytical concepts without the need for chemical reagents and without producing waste!These concepts can be applied wherever the samples are… and in real time!Bring the instrument to the sample…

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Use the same XRF system for a variety of:

• Teaching concepts• Laboratory experiments• Outreach programs• Field research projects

What Is In My Sample? CSI for the Student

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Scouting for elements…Toxic elements (As, Hg) in trophies or natural history specimens Pb in soil

Never ever believe numbersunless you know the physicsand your sample, atom by atom. (TENNET by B. Kaiser)

Answers vary as:• the inverse square of the distance to the element• exponentially relative to matrix density• exponentially relative to elemental X ray energy emission• exponentially relative to element location in the sample matrix• exponentially relative to beam filtering and energy• X-ray beam distribution• orders of magnitude relative to sample uniformity

In the Field

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Always review the raw spectrum; there are many treasures thereinUse the physics to your advantage• Voltage• Current• Filter• Secondary target• Variations of the above 4 • Subtraction• Normalization• Analysis locations• Front to back and Back to front• Transmission test or calculations

Your instrument system must giveyou control over all these thingsYou must have good visual real time access to the raw spectrum

So much for the PROBLEM hornet. I made him LUNCH!

And the Answer Is

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Something to scratch one’s head about?

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Innovative XRF Setup and Analytical Approaches for 5 Specific Measurement Treasures

1. Rapid accurate elemental field survey

2. Field drill core analysis3. Mineral screening at the

face4. Site mapping5. Instant elemental

knowledge

Getting the Answer

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Summary

Today you have learned how easy X-ray Diffraction and X-ray Fluorescence techniques are to use, and how useful they can be.

There is full information available from Bruker AXS on the background, theory and experiment for teaching X-ray analysis.

This information makes it simple to add diffraction, crystallography and spectrometry techniques to your undergraduate teaching curriculum.

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Any Questions?

Please type any questions you may have in the Q&A panel and then

click Send.

Getting Started with TOPASlive online training course

Dec 15 and 16, 2009 11:00 AM – 12:30 PM CST (US)(two 90-minute sessions)

Purchase and register all in one step under the Training section atwww.brukersupport.com

To Learn More About Structure Determination

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Completely automated operationStructure information when you need itQuick, reliable and effectiveBenchtop system designed for synthetic chemistsJoin contest today: http://www.bruker-axs.com

SMART X2S:Automated chemical crystallography solution

Visit us at:Keystone Symposium

Jan 8-13, Breckenridge, CO

Bruker AXS Benchtop SeminarJan 27, Houston, TX

MIT SymposiumFeb 12-13, Cambridge, MA

Pharmaceutical Powder X-ray Diffraction Symposium (PPXRD)Feb 22-25, Hilton Head Island, SC

PITTCONFeb 28 - Mar 5, Orlando, FL

American Physical Society (APS)Mar 15-19, Portland, OR

American Chemical Society (ACS Spring)Mar 21-25, San Francisco, CA

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