Oxygen Species Adsorbed on Oxides: Part 2.—Formation of (O3X on MgO)

Abstract

MgO surface containing adsorbed (O~)s ions reacts with excess oxygen to form the molecular ion (Oajs- This ion has been characterized by e.s.r. using oxygen enriched with 17O and shows a complex hyperfine structure. Heating at 400 K converts the (Oj)s ions to (O2)s and an isotopic exchange occurs between the various oxygen nuclei. The optical data indicate that a band close to 420 nm is associated with the (O2)s species. Calculations using electron affinity and bond energy data indicate that the reaction O“+O2->O2 is exothermic and that (O2)s must be considered as a possible adsorbed oxygen species on oxides.