ROTATIONAL-DYNAMICS IN ASSOCIATIVE DESORPTION OF HYDROGEN FROM PD(100) AND CU(111) SURFACES

The rotational dynamics in associative desorption of hydrogen from an s-metal and a transition metal surface is state-selectively investigat ed by resonantly enhanced two-photon ionization and by laser induced f luorescence. From these measurements rotational state populations, sta te-selective velocity distributions, and the spatial alignment of the rotational angular momentum can be deduced. Recently, fully six-dimens ional potential energy surfaces (PES) have been developed for this rea ction on both substrates which allow quantum mechanical simulations of the dynamics. First calculations provide a comparison with the experi mental data. The different chemical nature of palladium and copper is reflected in the rotational state population, the coupling of rotation to other degrees of freedom, and the spatial alignment of the rotatio n. For Pd(100) good agreement between theory and experiment is obtaine d, while for Cu(lll) the experimental data suggest that the azimuthal corrugation is significantly higher than assumed in the calculations.