Oxygène adsorbé sur platine; résultats expérimentaux et modèle d'interprétation

Isotopic exchange and programmed thermal desorption have been used to study the problem of the nature of the adsorbed states of oxygen on platinum. On strongly oriented ribbons (100 face), five adsorption states can be identified. At low temperature (120 K), the adsorption is partially molecular. Above 300 K, oxygen adsorbs completely dissociatively. The multiplicity of desorption peaks cannot be explained by the existence of distinct planes or adsorption sites. A model with two types of lateral interactions has been applied to take account of the experimental results. It is in agreement with recent result on (100) vicinal surfaces.