Gas-surface scattering from W(100): Kinetic energy dependence of the effective corrugation

Angular and velocity distributions have been obtained for the scattering of argon and N2 from a W(100) surface for incidence energies, Ei, in the range 0.03-5.5 eV, and surface temperatures, Ts, from 90 to 1700 K. For Ei < 0.1 eV, we find broad angular distributions (> 60° FWHM) which are relatively insensitive to Ts and velocity distributions which are inconsistent with parallel momentum conservation, indicating a relatively corrugated interaction potential. Increasing Ei first causes a rapid narrowing in these distributions, but as Ei exceeds ~ 2 eV, they broaden again, as the effective corrugation again becomes large. © 1988.