抄録
We investigate and discuss the dynamics of H abstraction from Cu(111) by performing quantum dynamics calculations. We introduce a new theoretical approach that considers both quantum mechanically direct (the impinging H directly abstracts an adsorbed H) and indirect (the impinging H diffuses across the surface before it abstracts an adsorbed H) processes for H abstraction, and investigate how the coverage of adsorbed H on Cu(111) affects the vibrational and surface-parallel translational energy distribution of product H2. We expect that the H abstraction dynamics would depend on the coverage, because the shape of the corrugation depends on the coverage. Our results, for the case when the kinetic energy of the incident H Et=0.1 eV, confirm this expectation. The mean vibrational energies of product H2 decrease with decreasing coverage. On the other hand, the mean surface-parallel translation energies of product H2 increase with decreasing coverage. These results indicate that for the low coverage case, H abstraction occurs mainly through the indirect process, where the vibrational excitation of product H2 is suppressed, and the excitation for the surface-parallel translational motion of product H2 is enhanced, as compared with those for the high coverage case, where the H abstraction can occur through both direct and indirect processes.
