Aspects of the identification of iron oxidation states by Mössbauer isomer shifts

A hypothesis based on the literature data on the Mössbauer, structural, and magnetic parameters of different iron oxidation states is proposed, according to which changes in the electronic configuration of an iron ion that are caused by an electron (or a change of iron oxidation state by one) can vary the isomer shift by a constant (~0.33 mm s^?1), if it is assumed that the structure of the iron’s valent shell and iron spatial environment remain unchanged.