Characterization of oxygen adsorbed at Ba-modified Zn(0001) surfaces: Evidence for peroxo species

Abstract Ba-modified Zn(0001) surfaces exhibit an increased reactivity towards oxygen compared to a clean Zn(0001) surface. When the Ba coverage is small (θ Ba ∼ 0.1–0.5ML), the main surface species are ZnO and a peroxo species of the type (Ba,Zn)O 2 δ− . At higher coverages of Ba (θ Ba ∼ 0.75 ML), the initial species observed is BaO followed by ZnO and (Ba,Zn)O 2 δ− peroxo species. At still higher coverages of Ba (θ Ba ∼ 1.4 ML), BaO 2 is formed, but Zn is left unperturbed.