Low-temperature oxidation of alkali overlayers: Ionic species and reaction kinetics

► Comprehensive XPS study of low-temperature oxidation of all five, equally prepared alkali metal films. ► Unambiguous identification of atomic and molecular oxide species by O 1s core-level spectroscopy. ► Determination of the kinetics and the degree of dissociation of the oxidation. ► Demonstrating a clear chemical trend in the core-level shifts. ► Proof that XPS allows the identification of the oxide species.