HIGH-RESOLUTION SI K-EDGE AND L2,3-EDGE XANES OF ALPHA-QUARTZ AND STISHOVITE

Silicon K- and L2,3-edge XANES of alpha-quartz and stishovite are repo rted. The XANES spectra reveal the densities of the unoccupied Si 3s, 3p and 3d states in the band gap and the conduction band, and demonstr ate the large difference in the bonding of 4:2 coordinate alpha-quartz and 6:3 coordinate stishovite. The Si K- and L2,3-edge shifts are als o systematically related to the coordination of Si, Si-O bond length, Si-Si distance, Si-O-Si angle, Si-O bond valence and Si NMR chemical s hift of alpha-quartz and stishovite. These XANES spectra may be used a s a fingerprint in studying the structure of silicate glasses and melt s.