X-ray photoemission study of a sodalimesilica glass

Abstract A comparison is made between the X-ray photoemission spectra of the core levels and the valence band of a high purity sodalimesilica glass (21.3 wt.% Na 2 O5.2 wt.% CaO73.5 wt.% SiO 2 ) with those for fused silica. In the valence band of fused silica three peaks are observed whereas in the compound glass an additional peak is found above the high binding energy edge of the valence band. The presence of non-bridging oxygen in the sodalimesilica glass not only broadens the oxygen core level asymmetrically to lower binding energy, but also broadens the lowest energy peak in the valence band. It is this latter broadening which certainly contributes to the shift in the fundamental optical absorption edge to lower energy in this glass with respect to pure SiO 2 . An energy-level model is proposed for this glass. The diffusion of Na + ions to the surface is also observed.