Isomeric chemical shifts of Mössbauer γ-lines in isoelectronic compounds of tin, antimony and tellurium

Abstract

Isomeric chemical shift (IS) of the Mössbauer γ-line of Sn¹¹⁹(23.8 keV), Sb¹²¹(37.2 keV), Te¹²⁵(35.6 keV) have been studied in the isoelectronic complexes, SnHal^–2₆, SbHal^–1₆ and TeHal^–2₆(Hal = F, Cl, Br, I). Some other compounds of antimony have been also measured. The IS-values for these compounds depend linearly on the electro-negativity differences of the Mössbauer atom and ligand. The relation between relative change of the mean-square charge nuclear radius for three γ-transitions, (δR/R)_Sb/(δR/R)_Sn=–(5.5 ± 0.3) and (δR/R)_Te/(δR/R)_Sn=+(1.1 ± 0.2), is obtained by comparing these dependences. In 37.2 keV and 35.6 keV γ-transitions, the calibration of the IS value associated with one 5s-electron was also carried out. We have obtained the recoilless fraction of the 37.2 keV γ-quanta from Sn¹²¹O₂ source as equal to ƒ= 0.32^+0.04_–0.02. From the measurements of the dependence of resonance effect on the Sb₂O₅ absorber thickness the value of the total internal conversion coefficient for the 37.2 keV γ-transition is ∼10.