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

Abstract

The backscattering of light ions bombarding solid target has been investigated with the single-collision model, which assumes two straight line trajectories between the surface and the point of a wide-angle collision. This model allows to obtain the energy and angular distributions of backscattered ions in explicit form. Previous analytical theories considered the case when the probability of the scattering event is small and the ratio of the free path length λ 0 to the total inelastic range R T is large. In the present work, we obtained analytical solution for arbitrary values of the ratio λ 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 for moderate ratios λ 0/ R T the energy distribution of backscattered ions, integrated over all ejection angles, can have a maximum which was absent in the case of λ 0/ R T≫1. The results of the theory are confirmed by comparison with experimental and computer simulation data.