Where can we find the electron energy loss information in AES? and where can we find the electron energy loss information in XPS?
If we are looking at an oxide film and want to measure its band gap, which of the two methods will give us more information about the bulk and which will be more surface sensitive?
1) AES tables: the point of the Auger mechanism is that the emission energy is independent of the incident energy (as long as it's high enough). So, the tables of characteristic AES energies are kinetic energies, not binding energies or loss energies.
Article Auger catalog calculated transition energies listed by energ...
2) XPS energies are listed as binding energies, also not loss energies. Classical sets of cross sections would be the Yeh or Scofield Cross sections.
Article Atomic subshell photoionization cross sections and asymmetry...
https://www.osti.gov/servlets/purl/4545040/
https://a-x-s.org/research/cross-sections/
3) There is an evaluation method for getting the band gap energy with XPS, see Thorsten Schultz's answer here: https://www.researchgate.net/post/Is_there_any_recommended_way_to_measure_band_gap_and_fermi_level_of_wide_band_gap5eV_materials
If your spectra don't allow for the usage of this method, STS (scanning tunneling spectroscopy) would be my method of choice, if applicable. For the optical band gap, UV-Vis or Ellipsometry would be preferred.
Considering electron energy losses.
The Auger or photoelectron generated in the sample may loose kinetic energy by 2 processes.
1) Loss of kinetic energy by travelling through the sample:
There are widely used expressions (see the references mentioned in the answers to your other questions) and ongoing work in the framework of transport theory .
"... Eq. (2), suggests that the transport of low-energy electrons can be described by the same physical law as used in light scattering in interplanetary nebulae..." Werner et al. (2024) https://doi.org/10.1103/physrevlett.132.186203
By these processes the lower kinetic energy tail of the peak is broadened.
For analysis mainly the electrons without such losses are considered, therefore the used signal is from the topmost layers of the sample only (some nm).
2) Loss of a distinct values in kinetic energy by excitation of other electrons (e.g. ionization) or plasmons. Here a peak with a defined energy difference to a Auger or photoelectron peaks is observed.
Such plasmon losses contribute to the different shape of the KLL Auger peak in Al metal (strong plasmon losses) and in Al oxide.
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