Thermal Desorption of Isotopically Exchanged Molecular Oxygen from UV-Irradiated MgO Surfaces

Abstract

In the thermal desorption spectra (TDS) of molecular oxygen, three peaks of isotopically exchanged molecules ¹⁶O¹⁸O at 210, 260 and 650 K and a single peak of ¹⁶O₂ at 690 K are observed after adsorption of ¹⁸O₂ on UV-irradiated MgO powders. The formation of exchanged species is shown to be related to the presence of F_s⁺ centers on the surfaces.