Mössbauer-effect studies on Kr83 in bromide and bromate crystals

Mössbauer-effect studies have been performed using Kr83 sources produced by the - decay of Br83 (T12=2.4h) in various bromine compounds. Experiments were done with LiBr, NaBr, KBr, CsBr, NH4Br, KBrO3, and Kr - hydroquinone sources at 90°K using solid krypton absorber at 22°K. No isomer shift was observed for any of the sources, indicating that the Kr outer configuration is not perturbed by the induced dipole interaction with its neighbors. No "KrO3" species was detected as a result of the - decay of Br in KBrO3. Broad and symmetric emission lines were observed for the Kr-hydroquinone, the bromides, and the bromate, increasing in broadening in that order. This broadening has been explained on the basis of the formation of a local distorted crystalline field, as a consequence of the internal-conversion process of Kr83m. From the fact that a symmetric line is observed, it has been concluded that at least two modes of distortion are formed in such a way as to produce opposite signs of the electric field gradient. The Debye temperature calculated for the alkali-bromide sources was found to be 60°K in average, and for that of HN4Br a value of 90°K was derived. The techniques of source preparation and of the krypton absorber deposition are described.