Electronic structure of titania aerogels from soft x-ray absorption spectroscopy

Abstract

The electronic structure of ${\mathrm{TiO}}_{2}$ aerogels is studied by soft x-ray absorption near-edge structure (XANES) spectroscopy. High-resolution O K-edge and Ti ${L}_{2,3}$-edge XANES spectra of aerogels are compared with those of rutile, anatase, and unrelaxed amorphous phases of full-density ${\mathrm{TiO}}_{2}.$ Results show that all the main spectroscopic features of aerogels, reflecting the element-specific partial density of empty electronic states and correlation effects, can be attributed to the absence of long-range order in stoichiometric amorphous ${\mathrm{TiO}}_{2}.$ Based on these results, we discuss the effects of short- and long-range order on the electronic structure of ${\mathrm{TiO}}_{2}.$