Vibrational excitation of NO in NO/Ag scattering revisited

Abstract

Starting from the Newns-Anderson model, we compare the adiabatic with the non-adiabatic contribution to the vibrational excitation in NO/Ag scattering. In contrast to earlier investigations we assume that the NO affinity level is approximately singly occupied at the adsorption equilibrium position. This introduces drastic changes in the relative importance of adiabatic versus non-adiabatic effects. The non-adiabatic contribution to the vibrational excitation which is almost independent of incident energy turns out to be relevant only at low energies. At high energies the excitation is mainly due to the adiabatic trans-vib coupling. The surface temperature dependence of the vibrational excitation can be explained by a plausible temperature dependence of the potential parameters.