Submonolayer Oxidation of W(110): A High-Resolution Core-Level Photoemission Study
We have measured high-resolution core-level photoemission spectra from W(110) in the presence of submonolayer O coverages. Coverages ≤0.5 monolayer (ML) were obtained via room-temperature adsorption of O2. Higher coverages (<1.0 ML) were facilitated by a substrate temperature of 1500 K or a predose of alkali metal (K or Cs). Core-level shifts associated with the chemically distinct types of surface W atoms that occur for three-fold-coordinated O adsorption have been identified. The core-level shifts can be characterized by an oxygen-induced change in the average surface-atom core-level binding energy of ∼ 1.0eV per ML of adsorbed O. We show that the intensities of the surface-atom photoemission lines can be used to determine the absolute oxygen coverage.
"Submonolayer Oxidation of W(110): A High-Resolution Core-Level Photoemission Study," D. M. Riffe and G. K. Wertheim, Surf. Sci. 399, 248 (1998).