CHARGE-TRANSFER OF SLOW LIGHT-IONS INTERACTING WITH SURFACES

The charge transfer of slow atoms colliding with a surface is studied by means of a LCAO-method supplemented with a LD many-body contributio n. Atomic levels and the parameters controlling the atom-surface inter action are obtained for H and He on Al(100). The method is well suited for analyzing short ion-surface distances, where the strong coupling promotes molecular orbitals. Charge transfer processes are finally cal culated by solving Keldysh-Green function equations that describe the full quantum process associated with the ion-surface interactions. The se equations give a specific prescription for calculating velocity and three-dimensional crystal effects, taking into account the two-dimens ional surface periodicity. Calculations for some specific cases are pr esented.