Neutralization of He+ ions in front of an aluminum surface

We report electron spectra obtained from grazing incidence collisions of He+ ions with an Al(111) surface at collision energies ranging from 200 eV up to a few keV. The part of the spectra due to potential electron emission is analyzed in terms of a rate equation model that uses transition rate constants for resonant charge exchange- and Auger-type processes, and interaction energies between the projectile and the surface. It is shown that, if recently obtained theoretical interaction energies and rate constants are used in the model, calculated and experimental electron spectra agree within experimental error. From this it is concluded that (i) the theoretical input information on the He/Al system is consistent with experiment and (ii) the rate equation model is a valuable tool for analyzing electron spectra.