Alignment-resolved O2 scattering from highly oriented pyrolytic graphite and LiF(001) surfaces

We present an alignment-resolved O-2 scattering experiment showing that the alignment of an incident homonuclear diatomic molecule strongly influences the angular distribution of scattered molecule, the energy loss during the collision, and the trapping probability. Clear surface rainbow scattering has been observed on LiF(001) when O-2 is scattered along the [110] azimuth with its axis perpendicular to the scattering plane. The results can be understood based on the alignment dependence of the surface corrugation felt by an incident molecule. The fact that O-2 trapping probability on a highly oriented pyrolytic graphite surface is higher for end-on collision has been associated with the observed larger energy loss for this geometry.