Mechanisms for plasmon production by hollow atoms above and below an Al surface

Low-energy electrons ejected by 1-4 keV Ne4+ ion impact on an Al surface we re measured to study spectral structures near 11 eV attributed to the decay of plasmons. Absolute electron yields from the plasmon decay were primaril y studied as a function of the incidence angle of the Ne4+ projectile. Mode l calculations were performed to separate contributions from ions penetrati ng into the solid and ions reflected at the surface. Opposite energy depend encies were obtained for the two contributions suggesting that they are gov erned by potential and kinetic energy effects, respectively. (C) 2001 Publi shed by Elsevier Science B.V.