Trajectory and collision related neutralisation in low energy He+ ion scattering

A recent Surface Science Letter by MacDonald and Martin (Surface Sci. 111 (1981) L739) presents new experimental data on the neutralisation of He⁺ ions scattered from a Ni surface, which is interpreted in terms of a large collisional contribution to the neutralisation, not compatible with the usual Auger neutralisation picture. With the aid of new calculations, it is shown here that these data are consistent with an Auger neutralisation model involving local ion-atom charge exchange.