On the influence of incident angle in the scattering dynamics of D2 from NiAl(1 1 0)

The scattering dynamics of D2 from NiAl(1 1 0) has been investigated both experimentally and theoretically. Diffraction and rotational transitions of D2 from NiAl(1 1 0)[1 1̄ 0] have been measured at incident energies between 88 and 157 meV. The measurements were done using a setup which allows recording of diffraction patterns at a fixed angle of incidence. Elastic first-order diffraction and rotationally inelastic diffraction (RID) peaks were resolved over the whole incident energy range studied. The 0→2 transition probability was found to be about a factor of 2 higher than the one reported on Cu(0 0 1), whereas the 2→0 transition remained constant in the energy range investigated. Concerning the two rotational transition probabilities observed in experiment, one major conclusion of our work is that the behaviour they exhibit as a function of incident energy is independent of angle of incidence. All these observations are well reproduced by ab initio quantum mechanical calculations.