Reactivity of H_2O gas with the surface of polycrystalline Li_2O pellet

摘要

Ultraviolet/X-ray photoelectron spectroscopy was performed for a polycrystalline pellet sample of Li_2O, in order to elucidate the interaction of H_2O with the Li_2O surface. By H_2O-gas exposures of 0-13 L (1 L= 1.33 x 10~(-4) Pa s), a variation was induced in the electronic structure, corresponding to the formation of surface -OH via the dissociative adsorption of H_2O. No clear qualitative difference arose either in the electronic structure or in the reactivity to H_2O between the polycrystalline pellet and the Li_2O (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 H_2O-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.