Abstract
| - The availability of simultaneous measurements as a detailed function of surface coverage of boththe sticking probability and the differential heat for adsorption on a stepped surface provides a means ofanalyzing the coverage-dependent adsorbate distribution on a stepped surface. For C2H2 on Pt{211}, the initialheat of adsorption is measured as 270 ± 10 kJ mol-1 and the initial sticking probability is 0.84. On the basisof previously measured Pt−C bond strengths for adsorbates and steric considerations, it is concluded that atall coverages vinylidene is formed on the surface at 300 K. At low coverages step sites are preferred, wherethe adsorption heat is 280 kJ mol-1, with a Pt−C bond energy of 255 kJ mol-1. The terrace sites are occupiedat higher coverages with an estimated adsorption heat of ∼210 kJ mol-1 and Pt−C bond energy of ∼220 kJmol-1. Sticking probabilities on step and terrace sites are estimated as 1 and 0.78, respectively, at low coverage.
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