LI-ALKALI COVERED METAL-SURFACE COLLISIONS( NEUTRALIZATION AS A PROBEOF THE LOCAL ELECTRONIC POTENTIAL IN LI+)

A theoretical study of Li+ neutralization by collision on an alkali co vered Al surface is presented. The neutralization probability is compu ted for Li atoms back scattered from Al sites and from alkali sites on the surface. The calculations are performed with a model representati on using lithium as a representative for alkali adsorption. The result s reproduce the very large difference in neutralization probability fo r Li scattered from substrate and adsorbate sites experimentally obser ved by Weare and Yarmoff [Surf. Sci. 348 (1996) 359] and thus confirm the importance of local effects in atom-surface charge transfer. For s cattering from adsorbate sites, the neutralization is shown to be asso ciated with a very large excitation probability of the scattered Li at om. (C) 1997 Elsevier Science B.V.