Weak hyperfine interaction of E′ centers in gamma and beta irradiated silica

We report on the effects of photon (gamma) and electron (beta) irradiation in a dose range extending from 100 to 5 x 10(9) Gy in a variety of silica samples studied by electron paramagnetic resonance. The E-' centers and a weak intensity satellite signal of their resonance line were generated both in gamma- and in beta -irradiated samples. We investigated the dependence of their intensity on the irradiation dose. Evidence of the existence of a common generation mechanism for the related paramagnetic point defects is found. These defects are induced mainly through the conversion of precursors except at very high doses, where the direct activation from the unperturbed matrix is concurrent. Our data support the model attributing the satellite signal to the weak hyperfine structure of the E' center arising from interaction with a second nearest neighbor nuclear spin. (C) 2001 American Institute of Physics.