Emission Mössbauer spectroscopic studies of57Fe atoms produced in57Co-labelled trinuclear cobalt-iron halogenoacetate complexes

Abstract

Mixed-valence states of57Fe atoms produced after EC-decay of57Co in a series of trinuclear cobalt-iron halogenoacetate complexes, [CoIIFe 2 III O(CH3−nXnCO2)6(H2O)3] (0≤n≤3, X=Cl, Br, and I), were studied by comparing the results obtained by emission Mossbauer spectroscopy with those observed in absorption Mossbauer spectra of analogous trinuclear iron complexes, [FeIIFe 2 III O(CH3−nXnCO2)6(H2O)3]. Some of the emission Mossbauer spectra show a temperature-dependent mixed-valence state as found in the absorption Mossbauer spectra. Others show a somewhat different temperature dependence compared with the absorption Mossbauer spectra. The results were interpreted in terms of after-effects of the EC-decay.