Electron spin-lattice relaxation of the (SeO2)-radical in X-irradiated KH3(SeO3)2

The spin-lattice relaxation (SLR) times of paramagnetic irradiation centers in potassium trihydrogen selenite crystals (KTS) have been measured by the aid of the pulse saturation method. Irradiation of KTS with an X-ray tube operating at 35 kV during various irradiation times between 1 h and 5 h leads to the formation of (SeO2)- radicals in the concentration range of 1.4 x 1018 to 2.4 x 1019 cm-3. Experimental points of the electron SLR rate and lines from least square computer fit as functions of temperature and the concentration dependence of separated relaxation processes are given and discussed. Results show that the SLR processes are dominated by optical lattice vibrations and localized lattice excitations