Theory of charge exchange in the scattering of molecular ions from simple metals

Abstract

A description of the charge exchange between energetic diatomic molecular ions and metal surfaces is presented, which includes in a semiclassical way the coupling between the available exit channels. Explicit results for resonant electron capture during the scattering of ${\mathrm{H}}_{2}$${\mathrm{}}^{+}$ from Al(110) are given. For low incident energies, capture to both the X ${}^{1}$${\ensuremath{\Sigma}}_{g}^{+}$ and b ${}^{3}$${\ensuremath{\Sigma}}_{u}^{+}$ states occurs on the incident portion of the trajectory. Capture to the singlet state predominates for molecule-axis orientations nearly parallel to the surface, and to the triplet state for near-normal orientations. The axis-orientation dependence of the triplet occupation probability and the dissociation-fragment relative kinetic-energy distribution are calculated, as is the vibrational population distribution of the singlet ground state.