The relationship between an intrinsic 1.9eV photoluminescence (R band), and the 2.0 and 4.8eV excitation/optical absorption bands, was examined in specimens with various OH, Cl, and O2 concentrations and irradiation histories. A direct relationship was found between the intensities of the R-band luminescence, as measured using 4.0eV or resonance (1.94eV) excitation; although it was slightly super-linear, with an exponent of 1.13. A deviation from the exactly constant ratio between the band intensities in various glass samples was attributed mainly to inhomogeneous broadening effects. Also, a non-zero (-1.5%) degree of polarization in the R-band maximum region was confirmed during linearly polarized 4.8eV excitation, and established a close relationship between the 4.8eV absorption band and the R band. The results strongly suggested that the absorption bands at 2.0 and 4.8eV both originated from a single center, and the data agreed quantitatively with a proposed optical transition scheme for the non-bridging O hole center.

L.Skujá, K.Tanimura, N.Itoh: Journal of Applied Physics, 1996, 80[6], 3518-25