New predictions on magnetic rotational transitions in scattering of H2 by LiF(001)

New predictions are presented for the scattering of H-2 from LiF(001), based on a potential which includes che interaction between the quadrupole moment of H-2 and the surface ions. Large probabilities are found for transitions in which the magnetic rotational quantum number m(j) changes, contradicting the view that rotational scattering of small homoatomic diatomic molecules off inert surfaces obeys a Delta m(j) = 0 propensity rule. Scattering of unpolarized H-2 leads to rotationally polarized beams, suggesting a technique for constructing rotationally polarized beams of H-2.