Adsorption of oxygen on the (110) plane of tungsten at low temperatures

Abstract

Abstract Isotope labelling experiments have established that the adsorption of O2 on the W(110) plane at 20 K leads first to the formation of a dissociated atomic layer. A weakly bound molecular species, α-O2, forms only when the atomic layer is essentially complete (O/W = 0.6). The desorption of α-O2 was found to be first order with an activation energy of E = 1.9 kcal mole and a frequency factor γ = 3 × 109 s−1. The activation energy is shown to be less than the enthalpy of desorption and the meaning of this result is discussed.