ESR study of Sr(BrO3)2⋅H2O single crystals γ irradiated at 300 and 77 K

Abstract

The paramagnetic defect centers observed in Sr(BrO3)2⋅H2O single crystals γ irradiated at 300 K are identified as pseudo Vk centers of the type (A) (bBr–aBrO2)− and (B) (bBrO3–aBrO2)−. Both these centers occur at one site each. A comparison of the experimentally observed direction cosines with those calculated from the crystal structure shows that the separation between the secondary bromine (bBr) and primary bromine (aBr) nuclei is 0.366 nm in the case of radical (A) and 0.369 nm in the case of radical B. In addition, O3− and O− paramagnetic centers and a BrO− diamagnetic center have also been observed in the crystals γ irradiated at 300 K. After γ irradiation at 77 K, BrO32− centers occuring at two magnetically inequivalent sites were observed. Thermal and UV light bleaching effects on these centers are discussed.