H 2 + scattered off Al surfaces: The role of the negative ion resonance Σu+2

Abstract

A theoretical study of the electronic processes occurring in collisions of H2+ molecular ions on an Al surface is presented, with an emphasis on the molecular dissociation induced by electronic transitions. The H2+ neutralization proceeds through two different channels: the H2 (b 3Σu+) dissociative state (resonant process) and the H2 (X 1Σg+) ground state (Auger process). The Auger deexcitation process of the b state, mediated by the H2− (2Σu) resonant state is studied in detail and shown to result in an efficient quenching of the excited state and a reduction in the molecular dissociation probability. Its efficiency depends on the competition between the molecular dissociation and the electronic process. The importance of this process can explain the experimental observation of significant amounts of bound H2 molecules surviving the electronic processes.