Visible and near-IR absorption spectra of oxygen adsorbed on porous glass

Visible and near-IR absorption spectra were obtained for oxygen adsorbed at 80 K on porous glass at various surface coverages Θ by the adsorbate. The measurements were made on samples of porous glass, 0.4- to 7-cm long, with pore size d = 80 Angstrom. The position of the absorption bands of adsorbed oxygen was found to be independent of Θ within the range 0.2<Θ<6.5 and to coincide with that of the corresponding bands in the spectrum of liquid oxygen. The bandwidth of adsorbed oxygen grows with increasing Θ and reaches values typical of the liquid phase for Θ>2. The integrated intensities of all bands, including those known to be of dimole character (λ=634 and 577 nm) was shown to increase linearly with increasing Θ. It was concluded that the adsorbed oxygen is closer in the given conditions to the liquid than gas state. 14 refs., 3 figs., 2 tabs