Relevant effects of localized atomic interactions and surface density of states on charge transfer in ion-surface collisions

Through a time-dependent quantum-mechanical calculation of the H+ scattering by a highly oriented pyrolytic graphite (HOPG) surface, we are able to satisfactorily reproduce the interesting features we observed in ion scattering experiments in H+/HOPG system. We found that the combined effects of the semimetal character of HOPG together with the localized nature of the carbon atom states primarily determine the angular dependence and the magnitude of the ion fractions for large outgoing angles. The spin fluctuation effects (not considered in the present calculation) are discussed as one of the the main causes of the disagreement between the spinless theory results and the experiments for small exit angles. (authors)