Isotope and Surface Temperature Effects for Hydrogen Recombination on a Graphite Surface

We highlight the isotope and surface temperature effects for hydrogen atom recombination on a graphite surface. The reaction dynamics is studied using the semiclassical collisional method, according to which the mass and temperature effects are due to the coupling between the H/D dynamics and the dynamics of the phonon excitation/de‐excitation mechanism of the substrate. All possible collisional schemes with H/D adsorbed on the surface and H/D impinging from the gas phase are considered. In particular, we focus on the recombination reaction between an H atom colliding with a D atom adsorbed on the surface and a D atom incident on an H adatom. For H₂ and D₂ formation, the surface temperature effect is investigated by comparing the results obtained for T_S=800 K with those obtained at T_S=500 K and T_S=100 K. Despite the low masses involved in the dynamics, effective isotope and temperature effects were observed on the recombination probabilities, reaction energetics, and roto‐vibrational states of formed molecules. The results show the need for correct treatment of the multiphonon excitation mechanism in molecule–surface interactions.