ISSN:
0142-2421
Keywords:
Excitation depth distribution function
;
Auger electrons
;
Monte Carlo calculations
;
Universal cross-section
;
BASTIN 86 algorithm
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Physics
Notes:
A theoretical Monte Carlo model for calculations of the excitation depth distribution function (EDDF) defining the distribution of ionizations caused by impact of medium energy electrons has been developed. Within this model, the energy losses are described by the Universal cross-section, which has successfully been applied for peak shape analysis at medium energies. Furthermore, the proposed model accounts for the energy dependence of the differential elastic scattering cross-sections, which may be very pronounced at medium energies. It has been found that the mean range of L3 subshell ionizations in iron at 1250 eV extends only down to ∽40 Å. This result confirms an experimental value found recently from analysis of the Fe L3MM spectral shape. Very good agreement is also observed between experimental and theoretical mean ionization depths obtained at higher energies. The shape of the EDDF closely resembles the shape of the φ(ρz) function used in the formalism of electron probe microanalysis. Similarly with the φ(ρz) function, the EDDF initially increases with depth to reach a maximum and then monotonically decays. The EDDF resulting from the present theoretical model has been compared with the φ(ρz) function derived from the experimental data acquired at much higher energies (BASTIN 86 algorithm). Unexpectedly, this simple formula was in reasonably good agreement with the present calculations in the energy range 1250-4000 eV and for a wide range of atomic numbers. It is concluded that the BASTIN 86 algorithm is a reasonable approximation of the EDDF function for AES. © 1997 by John Wiley & Sons, Ltd.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
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