Dynamics of gas–surface interactions: Scattering and desorption of NO from Ag(111) and Pt(111)

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Abstract
Empirical potential energy surfaces have been constructed to describe the nondissociative interaction of NO with the (111) faces of Ag and Pt. Stochastic trajectory simulations employing these interaction potentials accurately reproduce experimental angular and velocity scattering distributions. Measured rotational energy distributions of scattered molecules, including the observed ‘‘rotational rainbow’’ features, are also reproduced quantitatively. Arrhenius prefactors for desorption are computed to be large (1016 s−1), and the translational and rotational ‘‘temperatures’’ of desorbed molecules are found to be lower than the surface temperature, in agreement with experiment. Sticking probabilities, desorption rates, and the rotational energy of desorbed and scattered molecules are all found to be strongly influenced by the dependence of the attractive region of the gas-surface potential on molecular orientation.