Effect of image potential and charge exchange on the trajectory of fast protons in surface scattering

Abstract

Fast hydrogen atoms with an energy of 25 keV are scattered off a clean and atomically flat W(100) surface under grazing angles of incidence. Switching of an electric field directed normal to the scattering plane allows the separation of angular distributions of scattered projectiles leaving the surface as neutral hydrogen atoms and as protons, respectively. We observe a shift for protons towards smaller angles of scattering in direct comparison with neutral atoms. Our experiments give evidence for an effect of image potential and charge exchange on the trajectory of scattered projectiles. The analysis of data allows one to deduce information on charge exchange in atom-surface interactions.