Optical Properties of TiO2-SiO2 Glass Over a Wide Spectral Range

Optical properties of vitreous SiO2 with 7.4 wt.% TiO2 are found by dispersion analysis of reflectivity measured in the infrared, visible, and ultraviolet augmented with literature values of vacuum-ultraviolet reflectivity and absorption. The principal infrared absorption associated with the titanium dopant occurs at 950 cm-1 in a deep minimum of the host silica absorption. We attribute this to a perturbation of the silica's absorption at 1076 cm-1 involving oxygen atoms bridging SiO4 and TiO4 tetrahedra. Strong ultraviolet absorptions of Ti4+ occur just below the silica exciton peak between 5.5 and 7.8 eV. We attribute these to charge-transfer transitions at TiO4 tetrahedra; i.e., bound excitons consisting of a Ti3+ ion and a hole shared by four oxygen neighbours