Correlation between the red photoluminescence band and the oxygen-deficient-associated defect centers in γ-irradiated silica glass

The origin of the red photoluminescence (PL) band at approximately 1.8 eV in the PL spectra of oxygen-deficient-type silica glass was studied using electron spin resonance (ESR). The ESR spectrum of oxygen-deficient-type silica revealed hyperfine (hf) interactions between the unpaired electrons of radicals and neighboring 29Si atoms. Eight hf lines were recorded at approximately 40.9, 9.5, 7.6, 4.26, 3.0, 2.5, 1.6, and 1.06 mT. The 40.9 mT line arises from the primary 29Si hf structure of the E' center (O3≡Si↑, ↑: unpaired electron). The other lines are associated with oxygen-deficient-associated defect centers [Si clusters or SiOx (x < 2) structure]. We studied the relationship between the intensity of the 1.8 eV PL band and the intensity of the ESR signal which arises from the oxygen-deficient-associated defect centers, in various silica glass synthesized by various methods in the presence of different amounts of oxygen. We also studied the spatial distributions of the 1.8 eV PL band intensity and the ESR signal intensity in one silica glass sample. These results suggest that the 1.8 eV PL band in the PL spectrum of oxygen-deficient-type silica glass is associated with the oxygen-deficient-associated defect centers in silica glass. (author)