Electronic structure analysis of α-SiO2 via x-ray absorption near-edge structure at the Si K, L2,3 and O K edges

The electronic structure of empty states in quartz (alpha-SiO2) has been investigated by calculating the individual contributions of Si 1s, 2p and O 1s to the x-ray absorption near-edge structure (XANES) spectra; excellent agreement has been found between the experimental data and full multiple-scattering calculations. On the basis of the comparison, the origins of the spectral transition features can be assigned unambiguously. Although symmetry-based molecular-orbital theory is qualitatively adequate for describing these spectra, the interpretation of the Si K-edge XANES spectrum exclusively in terms of a ground-stale potential is inappropriate in general.