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1.
Dedushenko S. K. Makhina I. B. Mar'in A. A. Mukhanov V. A. Perfiliev Yu. D. 《Hyperfine Interactions》2004,158(1-4):417-421
A colourless quartz crystal doped with 57Fe3+ was obtained by hydrothermal synthesis in an NH4F solution. The crystal was transformed into violet amethyst by gamma-irradiation. The change in colour was accompanied by changes in the Mössbauer spectrum that can be interpreted as the conversion of trivalent iron into the tetravalent state: Fe3+→Fe4+.
相似文献2.
Yu. D. Perfiliev V. S. Rusakov L. A. Kulikov A. A. Kamnev K. Alkhatib 《Hyperfine Interactions》2006,167(1-3):881-885
To explain line broadening in emission Mössbauer spectra as compared to the corresponding absorber measurements, the model of trapped electrons has been proposed. Auger electrons (emitted, e.g. after electron capture by 57Co or after the converted isomeric transition of 119mSn), as well as secondary electrons, may be trapped in the proximity to the nucleogenic ion. Electrons captured by lattice traps at different distances from the daughter ion induce an asymmetric distribution of quadrupole splitting in the resulting emission spectra, as shown in a few examples. This model is supported by estimates of quadrupole splitting values which may be caused by such trapped electrons located at specified distances from the nucleogenic atom. 相似文献
3.
Yu. D. Perfiliev M. I. Afanasov A. M. Babeshkin 《Journal of Radioanalytical and Nuclear Chemistry》1985,93(1):29-35
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. 相似文献
4.
A. A. Kamnev E. Kuzmann Yu. D. Perfiliev A. Vértes M. Ristić S. Popović S. Musić 《Journal of Radioanalytical and Nuclear Chemistry》2000,246(1):123-129
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. 相似文献
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6.
S. V. Stepanov V. M. Byakov Yu. D. Perfiliev L. A. Kulikov D. S. Zvezhinskii L. V. Dubov 《High Energy Chemistry》2016,50(2):109-114
Process of formation of the Auger blob (nanosized cloud of two or three hundred of ion–electron pairs) around a 57Co radioactive atom after E-capture followed by the emission of a cascade of Auger electrons by the daughter atom 57Fe has been considered. The effect of local temperature elevation in the Auger blob caused by energy emission during ionization slowing down of Auger electrons and the secondary electrons generated by them is discussed. Some consequences of this effect have been noted. 相似文献
7.
A. V. Bokov V. M. Byakov L. A. Kulikov Yu. D. Perfiliev S. V. Stepanov 《Hyperfine Interactions》2017,238(1):95
Being the main cause of cancer, almost all chemical carcinogens are strong electrophiles, that is, they have a high affinity for the electron. We have shown that positron annihilation lifetime spectroscopy (PALS) is able to detect chemical carcinogens by their inhibition of positronium (Ps) formation in liquid media. Electrophilic carcinogens intercept thermalized track electrons, which are precursors of Ps, and as a result, when they are present Ps atom does not practically form. Available biophysical data seemingly indicate that frozen solutions model better an intracellular medium than the liquid ones. So it is reasonable to use emission Mössbauer spectroscopy (EMS) to detect chemical carcinogens, measuring the yield of 57Fe2+ions formed in reactions of Auger electrons and other secondary electrons they produced with 57Fe3+. These reactions are similar to the Ps formation process in the terminal part the positron track: e++ e? =>Ps. So EMS and PALS are complementary methods for detection of carcinogenic compounds. 相似文献
8.
A. A. Kamnev L. A. Kulikov Yu. D. Perfiliev L. P. Antonyuk E. Kuzmann A. Vértes 《Hyperfine Interactions》2005,165(1-4):303-308
Emission Mössbauer spectroscopy with the 57Co isotope was used to study very dilute rapidly frozen aqueous solutions of cobalt(II) complexes with low-molecular-weight biomolecules (aromatic amino acids – anthranilic acid and L-tryptophan) and within a sophisticated biopolymer, bacterial glutamine synthetase, a key enzyme of nitrogen metabolism. The appearance of after-effects of the 57Co→57Fe nuclear transformation as well as the coordination properties of the cation and the ligands in the complexes are discussed on the basis of their Mössbauer parameters. 相似文献
9.
Alexander A. Kamnev Alexei G. Shchelochkov Petros A. Tarantilis Moschos G. Polissiou Yurii D. Perfiliev 《Monatshefte für Chemie / Chemical Monthly》2001,132(6):675-681
Summary. The iron(III) complex of indole-3-acetic acid (1) was prepared, and its physicochemical properties, mode of iron(III) coordination, and electronic structure were studied
using UV/Vis, diffuse reflectance infrared Fourier transform (DRIFT), and transmission 57Fe M?ssbauer spectroscopic techniques. The data obtained provide evidence that iron(III) is not only coordinated by the carboxylic O-donor
atom, but also via the conjugated π-electronic system of the pyrrole moiety involving both the non-shared electronic pair of the heteroatom
and the C(2)*C(3) double bond. Considering the well-known increased sensitivity of the pyrrole residue in indole derivatives
to oxidation as compared to the benzene ring, as well as the formation of a triple complex (peroxidase-1-O2) proposed for the enzymatic 1 oxidative degradation mechanism involving as a key step the Fe3+ → Fe2+ transition in the enzyme form as discussed in literature, it is concluded that iron(III) coordination with 1 can influence the redox properties of the pyrrole ring by affecting its π-electronic system.
Received September 17, 2000. Accepted (revised) October 31, 2000 相似文献
10.
S. B. Rozanov V. G. Bozhkov V. I. Perfiliev S. Yu. Turygin 《Radiophysics and Quantum Electronics》2003,46(8-9):692-699
We describe the design of a waveguide planar Schottky-diode mixer for frequencies of about 200 GHz and a measurement system for testing the mixer performance. A backward-wave oscillator with a frequency doubler was used as the local oscillator. The results of room-temperature measurements of the mixer conversion losses and noise temperature as functions of the frequency and power of the local oscillator are presented. 相似文献