The low temperature adsorption of oxygen onto Ni oxides

摘要: Abstract In this paper we report on the low-temperature, reversible chemisorption of diatomic oxygen onto NiO, grown in situ single-crystal Ni substrates. One narrow (γ) and two broad (α1, α2) thermal desorption peaks are observed, that exhibit no isotopic mixing during desorption. α1, α2 high-temperature states, with α1 existing to well above room temperature. Both a states induce large work-function increase adsorption. This adsorption absence consistent negatively charged species lying NiO plane. The is believed occur at Ni2O3 point defects, yielding combined saturation O2 coverage 0.11 ± 0.03 monolay low temperature y peak (125 K) induces small positive Δφ desorption, suggesting an charge. Possible sites for γ state step edges and/or domain boundaries. maximum 0.12 monolayers diminishes substrate annealing. For all three not associated OH or CO3 contamination, independent oxide epitaxy.