Quantum dynamics of an Eley-Rideal gas-surface reaction: Four dimensional planar model for H(D)(gas)+D(H)-Cu(111)

We present a quantum dynamical study for the abstraction reaction of hydrog en and its isotope on Cu(111) surface by a four-dimensional planar model. T he rigid surface corrugation has been explicitly treated. High vibrational and rotational excitation observed in our product-state distributions indic ates that the reactions occur mainly via the Eley-Rideal mechanism as sugge sted earlier by experiments as well as the three-dimensional flat surface m odel. The four-dimensional planar model using a cut through the six-dimensi onal LEPS (London-Eyring-Polanyi-Sato) potential energy surface essentially reproduces the isotope effects observed in experiment in the energy distri butions of the reaction product. The unreacted atoms are found either to bo unce back from the surface or to diffuse on the surface as atoms. A signifi cant concentration of diffusing atoms on the surface could result in an ass ociative desorption pathway and contribute to the experimental measurement of HD formation. (C) 1999 American Institute of Physics. [S0021-9606(99)023 12-0].