COVERAGE DEPENDENT DESORPTION-KINETICS OF CO FROM RH(111) - A THEORETICAL-ANALYSIS

For a triangular lattice gas with up to third-nearest neighbor interactions between CO molecules adsorbed on Rh(111), we calculate the desorption kinetics assuming quasi-equilibrium throughout the desorption process. These calculations are compared with linearized and essentially isosteric kinetic data that were obtained using a three molecular beam scattering arrangement. The experimental desorption rates and ordered adsorbate structure data, including phase transition temperatures, are accurately reproduced using transfer matrix calculations. From these calculations we obtain quantitative values for inter-adsorbate interactions extending out to third-nearest neighbor distances. Standard Monte Carlo simulations qualitatively show the correct trends in the coverage dependent rate data, but are quantitatively inadequate for this system since the wrong coverage dependence of the sticking coefficient is implicitly assumed.