Unified picture of the molecular adsorption process:: O2/Pt(111)

Tight-binding molecular dynamics simulations of the adsorption Of O-2/Pt(I 11) have been performed based on an ab initio potential energy surface. We demonstrate that, contrary to common belief, in this system the whole adsorption probability as a function of the kinetic energy can be understood in terms of trapping into chemisorbed molecular precursor states. This provides a novel unified picture of the trapping process which is relevant for the general understanding of adsorption. Furthermore, by simple steric arguments we are able to explain why O-2 does not dissociate on cold Pt(111) surfaces even at kinetic energies that are much greater than the dissociation barrier. (C) 2003 Elsevier B.V. All rights reserved.