No abstract

The structure and properties of the paramagnetic centers formed by g-irradiation at 77 K in sodium sulfate doped with nitrate ions have been investigated by the EPR method. The NO 2À 3 , NO 2 and SO À 4 radicals have been identified. The orientation of NO 2À 3 relation to crystallographic axes is determined. In the 77-400 K temperature range the transformations of observable radicals have been studied. The mechanisms of their formation and thermal annealing have been discussed. The symmetry of nitrate ions in sodium sulfate was investigated by diffuse reflectance infrared Fourier transform spectroscopy. At the concentration of NO À 3 up to 5.5 Â 10 18 g À1 the nitrate ion was supposed to have a planar or pyramidal configuration of the D 3h or C 3V symmetries. At the concentration of the dopant higher than 5.5 Â 10 18 g À1 the nitrate ions with the C 2V symmetry were observed.