Measurements were made of the excitation and emission energy dependence of the lifetimes of the 2.7eV photoluminescence band associated with O-deficient centers in silica glasses. The non-exponential behavior of this time decay was consistent with intrinsic conformational heterogeneity of these point defects in the amorphous matrix. Accordingly, these data were analyzed in terms of a radiative rate distribution. Both the surface and bulk typologies of these point defects were studied. The mean value of the lifetime distribution of the surface defects increased from 12 to 15ms varying the excitation energy from 4.6 to 5.2eV, and it increased from 14 to 15ms in the emission energy interval between 2.6 and 3.0eV. As well similar variations of the lifetime were observed for interior defects, when measured at different excitation and emission energies. It was also possible to estimate the width of the lifetime distribution of this ensemble of point defects in silica glass.

Conformational Heterogeneity of the Point Defects in Silica - the Lifetime of the Phosphorescence Band at 2.7eV. M.D’Amico, M.Leone: Journal of Non-Crystalline Solids, 2008, 354[2-9], 239-43