Reactivity of H2O gas with the surface of polycrystalline Li2O pellet

Ultraviolet/X-ray photoelectron spectroscopy was performed for a polycrystalline pellet sample of Li2O, in order to elucidate the interaction of H2O with the Li2O surface. By H2O-gas exposures of 0–13 L (1 L = 1.33 × 10−4 Pa s), a variation was induced in the electronic structure, corresponding to the formation of surface –OH via the dissociative adsorption of H2O. No clear qualitative difference arose either in the electronic structure or in the reactivity to H2O between the polycrystalline pellet and the Li2O (1 1 1) single crystal. The variation in the contribution of –OH to the total intensity of the O 1s peak was investigated as a function of the amount of H2O-gas exposure, and the result was discussed in conjunction with an adsorption/absorption model using a Monte Carlo simulation. It was indicated that not only adsorption, but also absorption up to a few surface layers occurred with a high probability even in the annealed sample.