The vibrational excitation of NO desorbing from NiO(100) after UV laser irradiation:: Is NO- a possible intermediate species?

We report on ab initio and wave packet calculations with the intention of simulating the vibrational excitation of NO desorbing from a NiO(100) surface after laser irradiation. The influence of the electrostatic field above the singly positively charged surface on the N-O equilibrium distance of the NO--like intermediate is investigated by Hartree-Fock calculations. It is shown that the field leads to a considerable shortening of the equilibrium bond length of NO-, whereas the equilibrium distance of the neutral NO molecule is only slightly modified. Taking this field effect into account, we are able to obtain quantitative agreement between experimental and theoretical vibrational state populations. (C) 1998 Elsevier Science B.V. All rights reserved.