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 γ2 under N2+ bombardment of a single crystal shows a dependence on ion incidence angle θ, which is analogous to the anisotropy of the yield γ1 under N+ impact. The ratio R2(θ)=γ2/2γ1<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 θ<ψL and the shadowing-caused bell-like pattern at θ>ψL, the Lindhard angle.