SURFACE-DIFFUSION OF CO ON PT(111) - A HREELS STUDY AT HIGH-TEMPERATURES

Surface diffusion of CO on Pt(111) has been investigated with HREELS for temperatures between 280 and 420 K by measuring the stationary spatial variation of coverage produced on the Pt(111) surface by permanent impact of a CO-nozzle beam for different elevated temperatures at which the coverage is mainly controlled by the competition of adsorption and desorption. The Arrhenius parametrization of the diffusion coefficients yields E(diff) approximate to 52.4 kJ/mol and a prefactor of 7.5 X 10(2+/-1) cm(2)/s. The data processing and the evaluation of the coverage dependent diffusion parameters are discussed in detail. The observed coverage dependence has been modelled by a simple random walk model and the quantitative results are compared with those of other studies.