Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Different methods of calculating efficiently the angular distribution of photoelectrons escaping from uniform amorphous and polycrystalline targets are analysed in detail. Comparison has been made between the analytical results and Monte Carlo simulation data. The analytical approach is based on the solution of the kinetic equation in the transport approximation. The Monte Carlo codes comprise the conventional forward simulation algorithm and the reverse trajectory method. The reverse trajectory method employs the reciprocity theorem and allows same statistically significant results to be obtained with less computational effort. The angular distributions of photoelectrons leaving Al, Si, Cu, Ag, Ta and Au samples have been calculated as a function of polar and azimuthal angles for electron energies relevant in quantitative XPS analysis. It has been found that both Monte Carlo methods provide equivalent results. The discrepancies between the transport approximation and the Monte Carlo data do not exceed, as a rule, 5%. The largest deviations of the analytical results from those found by Monte Carlo codes are observed in the vicinity of the emission directions, where the photoelectric differential cross-section has its minima, and are about 15%. The agreement between the results obtained by different approaches, corresponding to the magic angle geometry, is within 2% for all cases studied.
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