Interaction of oxygen with a Pd(110) surface. II. Kinetics and energetics

The interaction of oxygen with Pd(110) has been studied by thermal desorption spectroscopy (TDS), work function change (Δφ), and Auger electron spectroscopy (AES) at 100Thermal desorption spectra reveal three major peaks, a low temperature one (α) being from molecular adsorbates and the other two (β1 and β2) from atomic oxygen. The β1 state is believed to be associated with subsurface oxygen. At 100 K, the population of molecular oxygen increases with increasing oxygen coverage. Above 200 K, all adsorbates are present as atomic oxygen. The rate of population of β1 decreases as T increases. This is explained as a kinetic effect due to the formation of the c(2×4) structure which hinders population of the β1 state. The oxygen induced work function change is found to depend strongly on both oxygen coverage and T. At a given T, Δφ is controlled by surface oxygen coverage, surface structural changes, as well as the formation of subsurface oxygen. A decrease of the intensity ratio of certain spectral f...