Unexpected superlinear dose dependence of the E′1 centre in fused silica.

A superlinear dose response in quartz so far has been observed with thermoluminescence (TL), but not with optical-or electron spin resonance (ESR)-spectroscopy. Superlinear increase of the E'1 centre concentration by irradiation of fused silica measured by ESR spectroscopy was recently reported. The E'1 centre is observed in all forms of quartz and silica. However, the superlinear increase of its concentration was only measured in one species of fused silica with high sensitivity to gamma irradiation. For this species, the growth of the E'1 centre concentration by gamma irradiation was measured using ESR spectroscopy. The results are compared with the growth of the correlated optical E-band absorption. Thermoluminescence measurements performed with the same fused silica species indicate a correlation of the 415°C glow to the E'1 centre