Interaction dynamics of hydrogen at a Cu(111) surface

Abstract

We have used molecular beam and laser detection techniques to study the dynamics of adsorption and desorption of H 2 and D 2 at a Cu(111) surface. We have determined the adsorption probability for beams with kinetic energies up to 0.83 eV, vibrational temperatures up to 2300 K, and incidence angles from 0° to 60°. A detailed analysis of these data yields adsorption probability functions for molecules in individual vibrational states. We have also studied the internal state distribution of molecules scattered from the surface. These measurements provide state-resolved information on both adsorption and vibrational excitation. The adsorption and scattering studies have been complemented by studies of desorption dynamics, including preliminary measurements of the velocity distributions of molecules desorbed in specific quantum states. The desorption data are interpreted via the principle of detailed balance to give information on the temperature dependence of the adsorption probability functions. The vibrational dependence of the desorption velocity distributions reproduces trends predicted from the adsorption measurements.