Abstract
The scattering behavior of water molecules on silicon (100) surface was investigated by the molecular beam technique. We focused on the incident energy range covering the typical translational energy that gas molecules have in room temperature condition (35 - 370 meV). The results was compared with that for graphite surface, which was previously investigated by our group (Miyoshi, N., et al., J. Phys. Chem. A, in press). The atomic-scale roughness of silicon surface makes the scattering distribution considerably diffusive in spite of the incomplete energy accommodation. For relatively large energy range (≥ 65 meV), the decrease in the incident energy makes the scattering distribution closer to the cosine distribution. However, when the incident energy is further reduced to 35 meV, the distribution exhibits a peak at a sub-specular angle. The incident energy dependence of the directivity of the scattering on silicon surface is opposite to that observed on graphite surface. The post-scattering translational energy strongly depends on the scattering angle for the incident energy of 370 meV while it becomes almost direction-independent for lower energies.
