A photoemission study of BaO overlayers adsorbed on W(110) and their interaction with H2O, CO2, and O2

Abstract The electronic structure of barium oxide overlayers on W(110) and their interaction with H 2 O, CO 2 and O 2 has been examined using ultraviolet photo electron spectroscopy. At room temperature water vapor and carbon dioxide react with a c(5 × 1)-BaO monolayer adsorbed on W(110) to produce adsorbed OH and CO 3 species. Heating the W(110)−c(5 × 1)-BaO surface following water or carbon dioxide exposure dissociates the adsorbed hydroxide or carbonate. On the lower coverage c(7 × 1)-BaO and c(2 × 4)-BaO adlayers complete dissociation of a fraction of the adsorbed species is evident at room temperature. The interaction of oxygen with W(110) is enhanced by the presence of barium oxide on the tungsten surface. These results are compared with the findings of a previous study of barium oxide films adsorbed on W(100).