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Linking TEM Analytical Spectroscopies for an Assumptionless Compositional Analysis

Published online by Cambridge University Press:  06 March 2014

Gerald Kothleitner ,
Werner Grogger ,
Martina Dienstleder  and
Ferdinand Hofer
Gerald Kothleitner*
Affiliation:
Institute for Electron Microscopy and Nanoanalysis (FELMI), Graz University of Technology and Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
Werner Grogger
Affiliation:
Institute for Electron Microscopy and Nanoanalysis (FELMI), Graz University of Technology and Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
Martina Dienstleder
Affiliation:
Institute for Electron Microscopy and Nanoanalysis (FELMI), Graz University of Technology and Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
Ferdinand Hofer
Affiliation:
Institute for Electron Microscopy and Nanoanalysis (FELMI), Graz University of Technology and Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
*
*Corresponding author. [email protected]
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Abstract

The classical implementation for putting quantitative figures on maps to reveal elemental compositions in transmission electron microscopy is by analytical methods like X-ray and energy-loss spectroscopy. Typically, the technique in use often depends on whether lighter or heavier elements are present and—more practically—which calibrations are available or sample-related properties are known. A framework linking electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray (EDX) signals such that absolute volumetric concentrations can be derived without assumptions made a priori about the unknown sample, is largely missing. In order to combine both techniques and harness their respective potentials for a light and heavy element analysis, we have set up a powerful hardware configuration and implemented an experimental approach, which reduces the need for estimates on many parameters needed for quantitative work such as densities, absolute thicknesses, theoretical ionization cross-sections, etc. Calibrations on specimens with known geometry allow the measurement of inelastic mean free paths. As a consequence, mass-thicknesses obtained from the EDX ζ-factor approach can be broken up and quantities like concentrations and partial energy-differential ionization cross-sections become accessible. ζ-factors can then be used for conversion into EELS cross-sections that are hard to determine otherwise, or conversely, connecting EDXS and EELS in a quantitative manner quite effectively.

Keywords

X-ray analysisEELS analysiselemental quantificationζ-factorsabsorptionEELS cross-sectionschemical shifts
Type
EDGE Special Issue
Information
Microscopy and Microanalysis , Volume 20 , Issue 3 , June 2014 , pp. 678 - 686
Copyright
© Microscopy Society of America 2014 

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