ENDOR STUDY OF C-133 HYPERFINE COUPLINGS WITH SO3- RADICALS IN X-IRRADIATED PIEZOELECTRIC CS2S2O6 SINGLE-CRYSTALS

The ENDOR technique has been used to study Cs-133 hyperfine couplings of SO3- radical ions in X-irradiated Cs2S2O6 single crystals. The orientational dependent parameters for two couplings were obtained from the ENDOR spectra and assigned with the aid of ENDOR-induced EPR. The larger coupling, a(I)=30.55 MHz, was attributed to the Cs+(2)----S(2)O3.-interaction and the smaller coupling, a(II)=9.59 MHz, to the crystallographically different product Cs+(2)---S(1)O3.-. The difference in distances was estimated from the experimentally measured hf splittings using a point-dipole approximation, and was found to be in agreement with crystallographic data. A temperature dependence of hyperfine couplings was observed and possible explanations are discussed in terms of the displacements induced by the piezoelectric and pyroelectric properties of the CS2S2O6 crystal.