Theory of near-resonant charge-exchange in gas-surface reactions

A theory is presented for describing near-resonant charge-exchange processes occurring in gas-surface collisions. The surface is represented by a cluster of atoms and its electronic properties are obtained from the Diatomics in Molecules procedure. The Polyatomics in Molecules approach is used to calculate the gas-surface interaction potentials and couplings. Trajectories for the transition probabilities and nuclear variables are obtained from the common eikonal formalism. Preliminary results are presented for Na scattering from a W(110) surface. The surface consists of five W atoms. The approach of the sodium atom is perpendicular to the surface and it collides with the center W atom. Generally, it is found that the probability of electron transfer increases with the initial kinetic energy of the sodium atom (5-60 eV) and can attain values larger than 40%.