Eley–Rideal recombination of hydrogen atoms on a tungsten surface

Abstract

The Eley–Rideal recombination reaction of H chemisorbed on the four-fold site of W(001) at a surface temperature T_S = 500 K is studied using the fully three-dimensional semiclassical collisional model and an accurate potential energy surface for the H–W(001) system. The recombination probability, calculated at different collisional energies in the range (0.05–5) eV, shows a broad maximum around 0.4 for energies between 0.1 eV and 2.5 eV. The exothermic energy partitioning in the final states of the desorbing H₂ molecules shows that, at low impact energies, only the first three vibrational levels of the hydrogen molecule are energetically accessible, while at the higher impact energies vibrational levels up to v = 7 can be populated. The energy exchanged with the phonons surface is small but not negligible.