Backscattering of Electrons Evaluated by the Eikonal-approximation

Physical background of electron backscattering

“…The discrepancy seems to be smaller only for very thin films and low atomic numbers (Schmoranzer and Grabe 1976). The deviation factor of 2-3 seems to arise (i) from plural scattering already becoming noticeable for films only a few tenths of nm thick, as could be confirmed experimentally by Muller and Schroder (1977), and by Monte-Carlo calculations (Berger 1963, (ii) from the fact that the Rutherford scattering cross-section for larger atomic numbers and scattering angles {} > 90 0 is too small and has to be replaced by the ,Mott scattering cross-section or other higher approximations , Lehmann and Schoenebeck 1977, Hahn 1977a, (iii) partly from neglecting, in the simple theory presented above, the mean energy loss of the incident electrons travelling in the target before suffering a Rutherford collision. This mean energy loss, caused by processes discussed in section 3.1, enhances the effective Rutherford cross-section because of its energy dependence: the electron wavelength A increases and thereby also the backscattering constant Ctheor (9).…”