Observation of direct vibrational excitation in collisions ofH2andD2with a Cu(111) surface

Abstract

We have observed the direct vibrational excitation (v=0→v=1) of ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ molecules colliding with a Cu(111) surface. The dependence of this process on kinetic energy is found to be similar for both molecules, resembling the function determined for dissociative chemisorption of molecules in the v=0 state. This suggests that translational-vibrational coupling is strong only when molecules closely approach the dissociation barrier.