Dynamics of the direct reaction of hydrogen atoms adsorbed on Cu(111) with hydrogen atoms incident from the gas phase

Fast HD molecules are observed in the reaction of a beam of H(D) aotms with D(H) atoms chemisorbed on a Cu(111) surface at 100 K. The mean kinetic energy of these molecules is close to 1 eV, or about half of that available. Angular distributions of the nascent HD product are relatively sharp, are displaced slightly away from the surface normal in the specular direction, and display a small sensitivity to the incidence energy. Both the energy and angular distributions are different for D on H and H on D. Results are discussed in terms of a direct Eley-Rideal mechanism.