Molecular propane adsorption dynamics on Pt(110)−(1 × 2)

Abstract

The molecular adsorption probability of propane on clean and propane-covered Pt(110)-(l × 2) was measured as a function of incident translational energy, E i, incident polar angle, θ i, propane surface coverage, θ cov, and azimuthal angle at a surface temperature of 95 K. The dependence of the adsorption probability on E i, and θ i at all propane coverages reflects significant participation of parallel momentum in the adsorption process due to corrugation in the propane/Pt(110)-(1 × 2) interaction. When the tangential velocity component of the molecular beam is directed along the close-packed atomic rows (the [11̄0] direction), the initial adsorption probability increases with increasing θ i; however, the initial adsorption probability decreases with θ i, when the crystal azimuthal angle is rotated 90°, indicating parallel momentum exchange dominates the adsorption process on this azimuth. Adsorbed propane facilitates trapping; S 0 increases linearly with propane coverage up to 0.55 saturation coverage. As θ cov increases, corrugation in the adsorbed layer dominates the adsorption process for all angles of incidence, and the azimuthal dependence of the adsorption probability becomes negligible except at the most glancing angles of incidence. A sudden change in the coverage dependence of the adsorption probability is observed at surface coverages above 0.55 saturation coverage.