Unified picture of the molecular adsorption process: O2/Pt(1 1 1)

Tight-binding molecular dynamics simulations of the adsorption of O2/Pt(1 1 1) 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 O2 does not dissociate on cold Pt(1 1 1) surfaces even at kinetic energies that are much greater than the dissociation barrier. Π2003 Elsevier B.V. All rights reserved.