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Published on: May 10, 2021
Remarks on some reference materials for applications in elastic peak electron spectroscopy.
1Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland.
Summary
Accurate electron spectroscopy (AES, XPS) relies on inelastic mean free path (IMFP) data. This study recommends gold (Au) as a reference material for IMFP determination using elastic electron backscattering measurements.
Area of Science:
- Surface science
- Electron spectroscopy
- Materials science
Background:
- Quantifying results from Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) necessitates understanding the inelastic mean free path (IMFP) of electrons.
- The IMFP is crucial for determining the surface sensitivity of these electron spectroscopy techniques.
- Two primary methods exist for determining IMFPs: calculations from optical data and calculations from elastic electron backscattering intensity measurements.
Purpose of the Study:
- To identify a reliable reference material for determining IMFPs using elastic electron backscattering.
- To evaluate the agreement between calculated and measured elastic electron backscattering intensities for elemental solids.
- To establish a preferred element for IMFP standardization in electron spectroscopy.
Main Methods:
- Experimental measurement of elastic backscattering intensity at eight electron energies (200-1500 eV) and wide emission angles (35-74 degrees).
- Monte Carlo simulations of elastic backscattering probability for the same experimental conditions.
- Comparison of experimental data with calculated intensities using established IMFP values.
Main Results:
- A comprehensive comparison revealed that gold (Au) exhibits the best agreement between calculated and measured elastic electron backscattering intensities.
- The study found that surface energy losses significantly influence the emission angle dependence of elastic backscattering intensity.
- Previous analyses showed good agreement for Ni, Cu, Ag, and Au, but lacked a definitive reference material.
Conclusions:
- Gold (Au) is recommended as the reference material for determining inelastic mean free paths (IMFPs) via elastic electron backscattering.
- This recommendation facilitates more accurate quantification in electron spectroscopies like AES and XPS.
- Understanding the influence of surface energy losses is vital for precise IMFP determination.
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