Energy dissipation to tungsten surfaces upon hot-atom and Eley–Rideal recombination of H2

Abstract

Adiabatic and nonadiabatic quasi-classical molecular dynamics simulations are performed to investigate the role of electron–hole pair excitations in hot-atom and Eley–Rideal H₂ recombination mechanisms on H-covered W(100). The influence of the surface structure is analyzed by comparing with previous results for W(110). In the two surfaces, hot-atom abstraction cross sections are drastically reduced due to the efficient energy exchange with electronic excitations at low incident energies and low coverage, while the effect on Eley–Rideal reactivity is negligible. As the coverage increases, the projectile energy is more efficiently dissipated into the other adsorbates. Consequently, the effect of electronic excitations is reduced. As a result, the reactivity and final energy distributions of the formed H₂ molecules are similar for both abstraction mechanisms.