Scattering of molecular ions at grazing incidence from metal surfaces

Results of the studies on molecular ion scattering have been published previously or are in press. The most important theoretical result in the validity of the symmetry considerations in our case as proposed by Dum for electron-molecule interactions. This result is proven by the experiments using N2+ and O2+ molecular ions. The wavefunctions of the ionic and neutral states of these molecules are such that in case of O2+ only nonbonding states are filled by electron capture from the surface, whereas in case of nitrogen also the N2 ground state is accessible. The experiments using H2+ and Al(110) show qualitative agreement with the theoretical predictions. The evaluation of the center of mass energy distribution of the dissociated H atoms is in qualitative agreement with the model which implies Franck-Condon-Transitions from vibrationally excited H2+ into the b3 Σ/sub u/+ H + H states by resonant electron capture (dissociative attachment). The relative yield of H2 and H after the scattering is of the expected order of magnitude if the elastic surface scattering is taken into account. A quantitative test of the theorical result is not possible at present, since the ''surface rainbow'' effect deflect a large number of dissociated particles into the detector. The estimates of this effect are not accurate enough. This is clear when considering the numbers involved. The symmetry conservation predicts at 300 eV primary energy an H2/H ratio of for all particles and of 100:1 for a detector with a 1/degree/ acceptance angle. The surface rainbow effect may change this ratio by a factor of 20 to 50 bringing the expected ratio into the range of the experimental result of abut 2:1. Details will be published later. 6 refs., 3 figs