Energy distribution of light ions backscattered from a solid in the single-collision approximation

The backscattering of light ions bombarding solid target has been investiga ted with the single-collision model, which assumes two Straight line trajec tories between the surface and the point of a wide-angle collision. This mo del allows to obtain the energy and angular distributions of backscattered ions in explicit form. Previous analytical theories considered the case whe n the probability of the scattering event is small and the ratio of the fre e path length lo to the total inelastic range R-T is large. In the present work, we obtained analytical solution for arbitrary values of the ratio lam bda(0)/R-T. The solution holds for the case of normal ion incidence on the target surface and atom to ion mass ratios M-2/M-1 > 1. It is Shown that fo r moderate ratios lambda(0)/R-T the energy distribution of backscattered io ns, integrated over all ejection angles, can have a maximum which was absen t in the case of lambda(0)/R-T >> 1. The results of the theory are confirme d by comparison with experimental and computer simulation data. (C) 1999 El sevier Science B.V. All rights reserved.