Velocity distributions after laser-induced desorption of NO from NiO(100) - The role of the angular coordinate

The experimental velocity distributions of NO desorbing from a NiO(100)-surface are simulated using a time-dependent wave packet method. Including the polar angle between the surface normal and the adsorbate molecular axis yields bimodal distributions in the correct velocity range and reasonable desorption probabilities if a resonance lifetime on the order of 25 fs is assumed. For two-dimensional simulations, an angular-independent charge-transfer-state was chosen as excited state in order to investigate the influence of the electronic ground-state on the final state distributions. We compare our results with wave packet calculations using a representative ab initio angular-dependent excited-state potential energy surface using a three-dimensional Hamiltonian.