Charge transfer in grazing scattering on clean and oxygen covered Cu(1 1 0) surfaces: velocity effects

We have measured negative (F-) and positive (Na+, Li+) charge fractions produced by grazing scattering from the corrugated metallic Cu(1 1 0) surface. A wide range of incident energies and scattered angles were explored in order to analyse the effects of the parallel and perpendicular velocities of the projectiles on the charge transfer process. The obtained dependences of F- formation and of Na+ and Li+ neutralization with the parallel velocity are in good agreement with previous experimental and theoretical studies, which incorporate parallel velocity effects via the 'shifted Fermi sphere' model. The surface structure is then modified by adsorption of oxygen. The dependence of charge fractions with oxygen adsorption and the effects of velocity in the case of the Cu-O surface are analysed