  We performed scattering experiments using a rubidium (Rb) atomic beam on
paraffin films and measured the angular and velocity distributions of scattered
atoms. The paraffin films were prepared in various ways and characterized by
atomic force microscopy and X-ray diffraction. The films exhibited various
roughnesses and crystal structures. The paraffin films preserved the spin
polarization of the scattered atoms. The measured angular distributions of all
prepared films were consistent with Knudsen's cosine law. The velocity
distributions were well fitted by Maxwell's distribution, characterized by a
temperature much closer to the film temperature than to the atomic-beam
temperature. We therefore concluded that the Rb atoms were well thermalized
with the paraffin films via single scattering events.
