H-2(+) scattered off Al surfaces: The role of the negative ion resonance (2)Sigma(+)(u)

A theoretical study of the electronic processes occurring in collisions of H-2(+) molecular ions on an Al surface is presented, with an emphasis on th e molecular dissociation induced by electronic transitions. The H-2(+) neut ralization proceeds through two different channels: the H-2 (b (3)Sigma(u)( +)) dissociative state (resonant process) and the H-2 (X (1)Sigma(g)(+)) gr ound state (Auger process). The Auger deexcitation process of the b state, mediated by the H-2(-) ((2)Sigma(u)) resonant state is studied in detail an d shown to result in an efficient quenching of the excited state and a redu ction in the molecular dissociation probability. Its efficiency depends on the competition between the molecular dissociation and the electronic proce ss. The importance of this process can explain the experimental observation of significant amounts of bound H-2 molecules surviving the electronic pro cesses. (C) 1999 American Institute of Physics. [S0021-9606(99)70239-4].