Argon Scattering off the Surface of Liquid Indium:  Exit Angle and Energy Dependence

Energy- and angle-resolved intensities are reported for the scattering of argon atoms off the surface of liquid indium just above the melting temperature, for two different argon incident energies. The higher incident energy results show significant energy transfer from argon to liquid atoms, and the angular distribution of scattered argon atoms is relatively sharply peaked near the specular angle. The lower incident energy results show a small amount of energy transfer from liquid atoms to argon atoms, the energy distribution of the scattered argon atoms is nearly thermal, and the angular distribution is much less sharply peaked, although still not completely thermal. Molecular dynamics simulations of these experiments are performed, and most of the results are in reasonable agreement with experiment. Analysis of the simulation trajectories helps to provide a microscopic understanding of the experimental results.