EFFECT OF INITIAL ROTATIONS ON THE STICKING OF NO ON PT(111)

We report results from classical molecular dynamics simulations for th e sticking of NO on the Pt(lll) surface, with a potential energy surfa ce having deeper chemisorption wells on the atop and bridge sites than in the centre sites. The sticking decreases with increasing molecular translational energy because there is simply too much energy for the substrate to take up. It is found that supplying the molecules with a modest amount of rotational energy enhances sticking because they rota te from O-end down to N-end down and chemisorb, while those initially N-end down remain so because of the attraction into the chemisorption well. With greater rotational energy (J approximate to 30), the repuls ive O-end of the molecule is nearest the surface too frequently, causi ng molecules to scatter from regions higher above the surface, thereby reducing the sticking.