OXYGEN-ADSORPTION ON VARIOUS VICINAL FACES CLOSE TO THE (0001) BASAL PLANE OF RHENIUM

Three vicinal faces of rhenium, close to the (0001) basal plane, have been studied by Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES) and Mirror Electron Microscopy (MEM). The deviation from the base orientation varied between 2° and 6° and atomic steps of various densities were observed. The sticking coefficient at 350 K, is found constant and equal to 0.53 when the oxygen coverage varies from 0 to 0.5 monolayer and then decreases rapidly. The surface potential of Re(0001) initially decreases by -30 meV and then increases linearly to saturate at +700 meV. On the Re-(S)[14(0001) × (1120)] face, the surface potential variations are quite different and the saturation occurs at +1050 meV. The study of the LEED patterns during the oxidation on different stepped surfaces of rhenium, indicates that the structure, observed on Re(0001) and usually referred to as a p(2 × 2) structure, could also be interpreted as a p(2 × 1) structure with three possible orientations. A model for the oxidation is finally given which can account for these various observations. © 1979.