Scattering of Cl 2 from clean and Cl-covered Ag(111)

Abstract

Supersonic molecular beam scattering is employed to investigate the interaction between hyperthermal (translational energy E i = 1−3 eV) Cl 2 and a clean or Cl-covered Ag(111) surface. The angular distributions of Cl 2 scattered from a Cl-covered Ag(111) are very broad. The ratio of the densities measured at the surface normal and at the maximum of the distribution scales with the momentum of the incoming molecules parallel to the surface. This might be caused by the large corrugation of the covered surface or by trapping desorption, as was recently suggested by DeLouise for Cl 2 scattering from Cl-covered GaAs(110). Measurements done at a clean surface (coverage ≤ 0.1 monolayer) show a much sharper distribution. Thermal energy atom scattering (TEAS) is used to determine the initial sticking probability S 0 to be between 0.3 (1 eV, Θ i = 70°) and 0.8 (1 eV, Θ i = 60°).