Europium Mossbauer spectrum

The preparation of europium metasilicate hydrate from solutions of europium bromide and sodium metasilicate has been described.The kinetics and mechanism of the reduction of thiocyanato- and isothiocyanato-penta-amminecobalt(iii) ions by europium(ii) in acid solution have been discussed in terms of europium(ii) attack on the ambidentate bridging ligand at the end remote from the cobalt centre. The differences in the activation enthalpies for the reduction of the complexes were attributed to (a) differences in enthalpy of formation of the precursor complex Eu - X - Co (NH3)5, and (b) ease of stretching of the Co—S or Co—N bond in the precursor complex. The low-temperature Mossbauer spectrum of EUH2 suggested the covalent transfer of electron density. to the metal 6s orbital to be more marked in EuH2 than EuO. ... 

The Mossbauer spectrum of the europium compound has a chemical shift of -13.00 mm/s relative to EuFj with a half width of 5.50 mm/s. The shift value falls within the range found for ionic divalent europium compounds (-15.0 to -12.8 mm/s). The chemical shift in Eu(CN)j is 0.75mm/s with the half width 2.74 mm/s. The explanation of the broad band in the spectrum of the divalent europium compound may be the participation of the d-orbital in the bonding (Colquhoun et al., 1972). 

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