ΔM_j transitions in homonuclear molecule scattering off corrugated surfaces. Square and rectangular lattice symmetry and purely repulsive interaction

In this paper, we present the first formal and computational studies of Δm_j transitions occurring in homonuclear molecule-corrugated surface collisions. The model potential is a pairwise additive one which correctly incorporates the fact that Δm_j-transitions occur only for corrugated surfaces (provided the quantization axis is chosen to be the average surface normal). The principal results are: (a) Δm_j transitions are extremely sensitive to lattice symmetry; (b) strong selection rules obtain for specular scattering; (c) the magnitude of Δm _j-transition probabilities are strongly sensitive to surface corrugation; (d) the Δm_j transitions depend strongly on diffraction peak; (e) the ratio of molecular length to lattice dimension (r/a) has a strong influence on the magnitude of Δm_j-transition probabilities [with the probabilities increasing as (r/a) increases]; (f) Δm_j rainbows are predicted to occur as a function of the (r/a) ratio increases; (g) Δm_j transitions and the Δm _j rainbow are expected to accompany Δj-rotational rainbows; (h) such magnetic transition rainbows accompanying Δj rainbows are suggested as an explanation of recent experimental observations of quenching of NO polarization for larger Δj transitions in NO/Ag(111) scattering.