The intrinsic 1.9eV photoluminescence band (R-band) of neutron-irradiated synthetic silica glass was studied by using site-selective photoluminescence excitation in the 2.0eV absorption band, and transient spectral hole-burning techniques. Measurements of the low-energy wing of the zero-phonon line intensity distribution function confirmed the predicted near-Gaussian shape; with a peak at 1.93eV and a half-width of 0.086eV. The homogeneous shape of the emission contour (single-site spectrum) was evaluated by using a selective saturation method. This revealed a phonon side-band with a peak at 60/cm and a width of about 500/cm. The total Huang-Rhys factor was estimated to be 1.5, and the partial Huang-Rhys factor for interaction with the 890/cm local vibration was 0.08. An analysis of the spectral parameters indicated that the R-band could not be due to peroxide or ozonide molecular ions, and supported the attribution of the center to a non-bridging O hole center.

L.Skuja, T.Suzuki, K.Tanimura: Physical Review B, 1995, 52[21], 15208-16