Nature of radiation absorption centers in silica glass

Abstract

Optical fibers as detectors of radiation have a lot of advantages: big length, little diameter, no electrical interference, and an opportunity to measure radiation from the spread source. Optical characteristics of pure silica glasses as a material for optical fibers are very important. Spectroscopic parameters of high-purity silica glasses made by sol-gel technology have been investigated. Absorption bands are formed near 4.6, 2.0, 1.7 eV when glasses are subjected to (gamma) -rays. This absorption bands are considered to be due to nonbridging oxygen hole centers (NBOHC). Dependence of integral absorption in the bands on irradiation dose for different samples of high-purity silica glass was received. Integral absorption in 4.6 eV-band increased with increasing of dose. And integral absorption in 2.0 eV-band also increased with increasing of dose, but position of its maximum shifts to smaller value of energy in samples with great content of oxygen. This shift is explained by increasing of absorption in 1.7-eV band. The experimental data gives that absorption bands are determined by presence of different types of NBOHC in the sample. Absorption band near 2.0 eV is due to NBOHC equalsVSi-O(arrow up). Absorption band near 4.6 and 1.7 eV is due to NBOHC equalsVSi-O - . The intensity of absorption band near 1.7 eV is determined by concentration of oxygen in the sample.