ESR, OPTICAL-ABSORPTION, AND LUMINESCENCE STUDIES OF THE PEROXY-RADICAL DEFECT IN TOPAZ

Fast-neutron irradiation of natural topaz crystals produces a single paramagnetic radiation damage center in high concentration. ESR of this center shows a holelike spectrum with S = 1/2 and a strongly anisotropic g tensor: g(xx) = 2.0027, g(yy) = 2.005 5, and g(zz) = 2.0407. We identify this defect as an intrinsic O2- center in the form of a peroxy radical. The orientation of the g tensor helps confirm this assignment, as does the extraordinary thermal stability; annealing temperatures near 800-degrees-C are required for complete removal. Two uv absorption bands are associated with the peroxy radical, each with oscillator strength near 0.09. Pumping in the higher energy band leads to a polarization-sensitive 2.5-eV luminescence; the other uv band apparently relaxes nonradiatively.