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Bethe ionization cross‐sections: A quantitative survey on calculating the backscattering factor in AES
Author(s) -
Lee C. L.,
Ong C. K.
Publication year - 1992
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740190144
Subject(s) - cross section (physics) , ionization , atomic physics , monte carlo method , electron , physics , range (aeronautics) , energy (signal processing) , work (physics) , ionization energy , computational physics , chemistry , nuclear physics , materials science , statistics , mathematics , quantum mechanics , ion , composite material
The objective of this work is to investigate the usefulness of the Bethe cross‐section with Powell parameters for possible future use in quantitative AES. The Powell energy‐dependent parameters are obtained from a least‐squares fit to various experimental and calculated work on ionization cross‐sections and are proven to have an accuracy of better than about 1% for U nl > 4 ( U nl = E 0 / E nl ), where E 0 is the incident electron energy and E nl is the binding energy of the electrons in the nl ‐shell. This cross‐section was quantum mechanically derived from the first Born approximation by Bethe and its use can be extended to lower‐energy ranges as evidenced from the Fano plots available. This means that the cross‐section has the advantages of a closer fit to experimental data and is within the energy range of interest in AES. A simple Monte Carlo approach has been adopted to calculate the backscattering factor and related Auger intensity lines using this cross‐section for C, Si, Cu and Ag elements. Results compared with both recent experimental data and Gryzinski cross‐section results indicate strongly that the Bethe cross‐section can be used for future quantitative analysis in AES.