H atom abstraction of D adsorbed on Si(100): dynamical evidence for an Eley-Rideal mechanism

Kinetic energy distributions are reported for the HD product from the reaction of incident gas phase H atoms with D adsorbed on Si(100). For an incident kinetic energy of nominally 1 eV, the HD product kinetic energy distribution extends up to the nominal available-energy limit and has a mean value of 1.2–1.3 eV, providing dynamic evidence for a direct Eley-Rideal mechanism. For higher incident H atom kinetic energies, the HD product kinetic energy distribution broadens while the mean value remains unchanged, suggesting that energy loss to the substrate becomes more significant and the reaction becomes less Eley-Rideal-like.