Experiments on scattering of molecular beams on polycrystalline platinum surfaces

A high-intensity molecular beam apparatus has been constructed and the spatial distributions of argon and nitrogen beam scattered on polycrystalline platinum surfaces were measured. A skimmer-orifice having a new configuration, and related measuring devices were constructed in order to carry out an accurate measurment of the flux distribution. In relation to the flux distribution of reflected molecules, diffuse scattering patterns are obtained for surface temperatures lower than 1000C, while the flux distributions obtained at surface temperatures higher than 1000C can be explained by the simple superposition of diffuse and lobular scattering patterns. The pattern of the lobular reflection qualitatively agrees with the hard-cube theory. (auth.)