Hyperfine splitting of EPR spectra of paramagnetic centers created by gamma irradiation of cesium trihydrogen selenite

The EPR spectra of gamma irradiated cesium trihydrogen selenite at 250C were analyzed to determine g and hyperfine tensor principal values and direction cosines. The observed spectra were from a single type of center with g11, g22, and g33 equal to 1.995, 2.031, and 2.007 (+- 0.002), respectively. Hyperfine splitting from 133Cs and from 77Se was observed with A11, A22, A33 values of 11.9, -7.7, -7.2 G and 263, +- 85, +- 100 G, respectively. The principal axes of g and the 77Se hyperfine tensor are nearly aligned with the special directions of one face of one of the SeO3 pyramids, indicating that the center is an SeO-2 radical