Adsorption effects on resonant charge transfer in atom-surface scattering

The probability of positive ionization of an atom impinging on a solid surface is calculated by numerical solution of the equations of motion of the time-dependent molecular orbitals of the system. The model is applied to the scattering of Na atoms, in the energy range 50–1000 eV, from a W(110) surface. The presence of Na adatoms is considered and found to hinder the ionization process. This reduction in the charge-transfer probability arises because of the lowering of the surface work function brought about by increasing adatom concentration.