The effect of crystalline structure on molecular effect in ion-induced electron emission

The results of experimental and theoretical study of the molecular effect in ion-induced electron emission from single crystal and polycrystalline materials are presented. It has been found that the electron emission yield gamma(2) under N-2(+) bombardment of a single crystal shows a dependence on ion incidence angle theta, which is analogous to the anisotropy of the yield, under N+ impact. The ratio R-2(theta)=gamma(2)/2 gamma(1)< 1 exhibits, for single crystals, a drastic angular dependence, which was successfully described on the basis of electron sweeping-out mechanism by conjunction of both the sharp channeling at theta <psi(L) and the shadowing-caused bell-like pattern at theta >psi(L), the Lindhard angle. (c) 2008 Elsevier Ltd. All rights reserved.