Gamma-x ray coincidence Mössbauer spectroscopic study of the aftereffects in sulfate hydrates

The anomalous charge states formed after the electron capture decay, of57Co in FeSO4·H2O and FeSO4·7H2O are investigated using the conventional Mossbauer emission spectroscopy and a gamma-X ray coincidence method. This method is based on the idea that a Mossbauer spectrum observed with the coincidence technique only when K-X rays are emitted is reflected by isolated events with a reduced influence of the Auger-electron self-irradiation. The formation of the anomalous electronic and structural configuration is attributed to the self-radiolysis of the H2O and SO 4 2− ligands in the nearest and the second nearest coordination shells around the decaying atom.