Molecular knife throwing: aiming for dissociation at specific surface sites through state-selection

We perform a quantum study of the dissociative adsorption of H-2 molecules on the Cu(100) surface. By calculating the reaction probability at specific surface sites, we find that, even at low collision energies, reaction is n ot necessarily dominated by the site with the lowest potential barrier to r eaction. By controlling the vibration and collision energy of the molecules one could, in principle, selectively induce reaction at different specific surface sites, probing them individually. We also suggest an experiment th at could provide additional evidence for our predictions. (C) 2000 Elsevier Science B.V. All rights reserved.