The Mössbauer isomer shift in iron (III) sulfate

The Mössbauer spectra of the rhombohedral and monoclinic modifications of Fe(III) sulfate have been measured. The isomer shift is 0.496 mm s−1 relative to α-Fe for both modifications and the quadrupole splittings are 0.15 and 0.30 mm s−1, respectively. The isomer shift of Fe2(SO4)3 fits on a calibration curve of electron density versus isomer shift proposed by Barrett and Micklitz, and its position is consistent with a high degree of ionic character for the compound. It is proposed to include Fe2(SO4)3 as one of the calibration points for electron density versus isomer shift.