On argon beams as tools to probe surfaces

We present experimental data and a theoretical analysis for the scattering of an argon beam from the (001) surface of LiF. The scattering pattern of the Ar beam was investigated for incident energies between 0.089 and 0.350 eV and for a variety of polar and azimuthal incidence angles. We find a bilobular scattering pattern for small incidence angles and along the direction of maximum corrugation on the surface, and a broad peak centered around the specular direction for higher incidence angles. An interaction potential based on the effective medium theory has been evaluated. The corrugation of this potential across the surface is in fair agreement with the data interpreted using the classical rainbow angles. Such corrugation is smaller than the one determined by He scattering, in agreement with previous Ar/metal surface investigations.