Radiation induced color centers in silica glasses of different OH content

Color centers induced by gamma radiation in high-purity silica glasses with various OH contents were investigated in this work. Several measurements, UV-Vis absorption spectra, electron paramagnetic resonance and Fourier Transform Infrared spectra were performed after the glasses being irradiated by 1000 kGy gamma rays. The results show that E′ centers (Si), oxygen deficient centers (SiSi) and B1 centers are induced in all samples, while non-bridging oxygen hole centers (SiO) and aluminum-oxygen hole centers (AlO) appear only in low-OH JGS3 and medium-OH JGS2. The concentration of each color centers in high-OH JGS1 is lower than that in JGS2 and JGS3. It is found that different type and concentration of induced color centers are closely depending on the amount of the OH in the glasses. Through the recombination with atomic hydrogen released by photolysis of hydroxyl, the color centers named E' center, non-bridging oxygen hole centers and aluminum-oxygen hole centers, could be transformed into visible colorless groups such as SiH, H-bond SiOH and AlOH, which could be a good explanation for the suppressing effect of OH on the radiation coloration.