Charge exchange of fast metastable He-atoms in front of an Al(111) surface

A beam of keV metastable He atoms is produced by the passage of He- ions th rough an alkali vapour target and scattered under a grazing angle of incide nce from a clean and flat Al(I 1 1) surface. Charge exchange between atoms and surface is studied via the effect of image charge deflection on traject ories of scattered projectiles. The angular distributions for scattered ato ms are analyzed in terms of electron transition rates which form the basis for a Monte-Carlo computer simulation. Resonant charge transfer plays a dom inant role leading to an ionization of the metastable projectiles. The tran sition rates for this process are calculated by making use of the Coupled A ngular Mode (CAM) method and dynamic properties of the interactions are tak en into account by translational factors connecting the projectile and meta l frames of reference. (C) 1999 Elsevier Science B.V. All rights reserved.