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Abstract  

Samples of K3MnO4, V2O5 and K2RuO4 containing small quantities of 57Fe were prepared and the Mössbauer effect was measured at various temperatures. A single broadened line of the room temperature spectrum of K3MnO4 with an isomer shift of –0.292(1) mm/s (relative to sodium nitroprusside) was ascribed to the pentavalent iron ion in a tetrahedral coordination. A similar line ( = –0.30(1) mm/s) was observed in the spectrum of V2O5. Two distinct states of Fe5+, the lines of which have isomer shifts of –0.38(1) and –0.11(1) mm/s, were formed in K2RuO4. They were not stable and disproportionated to Fe6+ and Fe3+.

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Abstract  

Sodium ferrates(IV) and (VI) were synthesized by the reaction between Fe2O3 and Na2O2 in a dry oxygen stream. The Mössbauer data for the obtained samples are presented (for Na2FeO3=0.18(2) mm/s; for Na4FeO5=–0.54(2) mm/s). It was shown that pure K2FeO4 and Cs2FeO4 can be obtained by heating Fe2O3 with apropriate alkali metal peroxides.

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Abstract  

Alkaline solutions of iron compounds synthesized by anodic dissolution of metallic iron in NaOH media have been studied by Mössbauer spectroscopy. The values of the isomer shift on iron in higher oxidation states are presented. The formation of the peroxoderivatives of iron in the solutions were not fixed.

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Abstract  

The energy absorbed by immediate surrounding of disintegrating119mSn nuclei have been estimated by comparing the Mössbauer emission spectra of119Sn in some tin compounds with the absorption spectra of the same substances after -irradiation and by simple calculations of Auger electrons energy losses. The results obtained indicate that the observed post-effects of the119mSn decay are due to self-radiolysis and other processes, whose contributions depend on the individual properties of the matrices.

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Abstract  

57Co Mössbauer emission spectra of cobalt benzoylacetonate and 3-substituted acetyl-acetonates have been studied. All spectra reveal the same stabilized57Fe forms, though in a ratio depending on the substituent in the ligand. This dependence is interpreted in terms of the substituent effect on the nature of metal-ligand bonding.

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Abstract  

The mechanism of chemical transformations after57Co/119mSn/ decay in solids is discussed on the basis of recent results. The study of the effect of electron acceptor concentration indicates a significant role of mobile electrons during the stabilization process.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Yu D. Perfiliev, V. S. Rusakov, L. A. Kulikov, A. A. Kamnev, and K. Alkhatib

Summary  

Resonant lines observed in source experiments are usually significantly broader thanthosein the corresponding absorber experiments. In order to explain this phenomenon, the model of a trapped electron has been proposed. Auger electrons emitted, for instance, after electron capture by 57Со or after the converted isomeric transition of119mSn, as well as secondary electrons, may be trapped in the vicinity of the nucleogenic ion. An asymmetric distribution of quadrupole splittings in the resulting emission Mössbauer spectra is thus a consequence of electron capture by lattice traps located at different distances from the daughter ion. Estimates of quadrupole splitting values, which may be causedby trapped electrons located at different distances from the nucleogenic atom, support the above mentioned model.

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Abstract  

Mössbauer, FTIR and XRD analyses showed that in aqueous medium in air in the presence of L-tryptophan (Trp) or indole-3-acetic acid (IAA) the ambient-temperature ageing of the precipitates formed from ferrous sulphate at pH7 gave composite phases with varying proportions of -FeOOH (a dominating crystalline phase), -FeOOH (both fine-grained, showing superparamagnetic behaviour at 298 K, and relatively better crystallized) and amorphous ferric hydroxide. The experimental data suggested a competition for adsorption sites at the oxyhydroxide surface in the suspension during phase transformations, as well as the transformation of -FeOOH (and/or amorphous ferric hydroxide) to -FeOOH via the dissolution-reprecipitation mechanism. The formation of certain ferric oxyhydroxide phases in the presence of Trp and IAA — released e.g., in the course of bacterial and plant metabolism — can contribute to the regulation of soil mineral composition.

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