ELECTRON-SPIN-RESONANCE STUDY OF CENTERS FORMED IN GAMMA-IRRADIATED PBCL2 CRYSTALS

An analisis is presented by utilizing the electron spin resonance spectra of new defects which are produced in PbCl2 single crystals irradiated at liquid nitrogen temperatures with gamma-rays from a Co-60 source. One of the g tensor axes of the defects corresponds to the crystallographic c-axis, and the other two make an angle of about 12-degrees with the a- and b-axes. The components of the g-factor are g(x) = 1.494 +/- 0.005, g(y) = 1.322 +/- 0.005 and g(z) = 1.662 +/- 0.005. The principal axes of the hyperfine coupling tensor A are collinear with neither the g tensor axes nor the crystallographic axes. The resolved hyperfine structure indicates that these defects fit a model of the paramagnetic centers consisting essentially of an electron trapped at paired lead ions, that is, the Pb-2(3+) centers.