Rovibrationally inelastic scattering of (v=1, j=1) H-2 from Cu(100) experiment and theory

A comparison between experiment and theory is pet-formed for the scattering of (v = 1, j = 1) H-2 from Cu(100) at normal incidence. Experimentally, th is system was studied using molecular beam techniques, with stimulated Rama n pumping employed to overpopulate (v = 1, j = 1) in the incident beam, and resonance enhanced multi-photon ionization used to detect the H-2 scattere d in two (v = 1, j) states, and two (v = 0, j) states. Theoretically, six-d imensional wave packet calculations were performed, employing a new, extend ed potential energy surface that was computed with density functional theor y, using the generalized gradient approximation and a slab representation o f the metal surface. Theory and experiment are in good agreement for the su rvival probability, i.e., the probability for rovibrationally elastic scatt ering. However, the theory overestimates the probabilities for rotationally inelastic scattering (to v = 1, j = 3) and for rovibrationally inelastic s cattering (to v = 0, j=5 and 7) for channels that could be determined exper imentally. The cause of these discrepancies is discussed, as are possibilit ies for future improvements in the theory as well as the experiment. (C) 20 01 American Institute of Physics.