TRAPPING DYNAMICS OF XENON ON PT(111)

The dynamics of Xe trapping on Pt(111) was studied using supersonic atomic beam techniques. Initial trapping probabilities (S0) were measured directly as a function of incident translational energy (EinT) and angle of incidence (θi) at a surface temperature (Tins) 95 K. The initial trapping probability decreases smoothly with increasing ET cosθi;, rather than ET cos2θi, suggesting participation of parallel momentum in the trapping process. Accordingly, the measured initial trapping probability falls off more slowly with increasing incident translational energy than predicted by one-dimensional theories. This finding is in near agreement with previous mean translational energy measurements for Xe desorbing near the Pt(111) surface normal, assuming detailed balance applies. Three-dimensional stochastic classical trajectory calculations presented herein also exhibit the importance of tangential momentum in trapping and satisfactorily reproduce the experimental initial trapping probabilities. © 1990.