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11.
V. A. Belyakov V. A. Burdov D. M. Gaponova A. N. Mikhaylov D. I. Tetelbaum S. A. Trushin 《Physics of the Solid State》2004,46(1):27-31
The temperature dependence of the photoluminescence (PL) spectrum of silicon quantum dots (QDs) is studied both theoretically and experimentally, and the time of the corresponding electron-hole radiative recombination is calculated. The dependence of the recombination time on the QD size is discussed. The experiment shows that the PL intensity decreases by approximately 60% as the temperature increases from 77 to 293 K. The calculated characteristic recombination time has only a weak temperature dependence; therefore, the decrease in the PL intensity is associated primarily with nonradiative transitions. It is also shown that the phonon-assisted radiation is much more efficient than the zero-phonon emission. Moreover, the zero-phonon recombination time depends on the QD radius R as R8, whereas the phonon-assisted recombination time depends on this radius as R3. 相似文献
12.
D. S. Korolev A. B. Kostyuk A. I. Belov A. N. Mikhaylov Yu. A. Dudin A. I. Bobrov N. V. Malekhonova D. A. Pavlov D. I. Tetelbaum 《Physics of the Solid State》2013,55(11):2361-2367
The photoluminescence spectra of erbium centers in SiO2 films with ion-synthesized silicon nanoclusters under nonresonant excitation were investigated. Erbium was introduced into thermal SiO2 films by ion implantation. The dependences of photoluminescence intensity on the dose, the order of ion implantation of Si and Er, the annealing temperature, and additional Ar+ and P+ ion irradiation regimes, i.e., factors determining the influence of radiation damage and doping on sensitization of erbium luminescence by silicon nanoclusters, were determined. It was found that the sensitization effect and its amplification due to doping with phosphorus are most pronounced under the conditions where nanoclusters are amorphous. The quenching of photoluminescence due to radiation damage in this case manifests itself to a lesser extent than for crystalline nanoclusters. The role of various factors in the observed regularities was discussed in the framework of the existing concepts of the mechanisms of light emission and energy exchange in the system of silicon nanoclusters and erbium centers. 相似文献
13.
A Planar‐Chiral Rhodium(III) Catalyst with a Sterically Demanding Cyclopentadienyl Ligand and Its Application in the Enantioselective Synthesis of Dihydroisoquinolones 下载免费PDF全文
Dr. Evgeniya A. Trifonova Nikita M. Ankudinov Dr. Andrey A. Mikhaylov Dr. Denis A. Chusov Dr. Yulia V. Nelyubina Prof. Dr. Dmitry S. Perekalin 《Angewandte Chemie (International ed. in English)》2018,57(26):7714-7718
The rapid development of enantioselective C?H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee). 相似文献
14.
A. A. Mikhaylov A. G. Medvedev T. A. Tripol’skaya E. A. Mel’nik P. V. Prikhodchenko O. Lev 《Russian Journal of Inorganic Chemistry》2016,61(12):1578-1583
Using peroxostannate as a precursor, a composite material based on tin dioxide and carbon black was obtained, in which tin dioxide forms a coating on the surface of carbon black nanoparticles. The synthesized material was characterized by electron microscopy and X-ray powder diffraction analysis, and also the electrochemical characteristics of this material as an anode material for lithium-ion batteries were studied. The material demonstrates good stability and rate performance, which is indicative of the efficiency of the peroxide method for producing promising inexpensive anode materials based on tin dioxide and carbon black. 相似文献
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Dr. Alexey A. Mikhaylov Dr. Alexander G. Medvedev Dr. Andrei V. Churakov Dmitry A. Grishanov Dr. Petr V. Prikhodchenko Prof. Dr. Ovadia Lev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2980-2986
Tellurium–peroxo complexes in aqueous solutions have never been reported. In this work, ammonium peroxotellurates (NH4)4Te2(μ‐OO)2(μ‐O)O4(OH)2 ( 1 ) and (NH4)5Te2(μ‐OO)2(μ‐O)O5(OH)?1.28 H2O?0.72 H2O2 ( 2 ) were isolated from 5 % hydrogen peroxide aqueous solutions of ammonium tellurate and characterized by single‐crystal and powder X‐ray diffraction analysis, by Raman spectroscopy and thermal analysis. The crystal structure of 1 comprises ammonium cations and a symmetric binuclear peroxotellurate anion [Te2(μ‐OO)2(μ‐O)O4(OH)2]4?. The structure of 2 consists of an unsymmetrical [Te2(μ‐OO)2(μ‐O)O5(OH)]5? anion, ammonium cations, hydrogen peroxide, and water. Peroxotellurate anions in both 1 and 2 contain a binuclear Te2(μ‐OO)2(μ‐O) fragment with one μ‐oxo‐ and two μ‐peroxo bridging groups. 125Te NMR spectroscopic analysis shows that the peroxo bridged bitellurate anions are the dominant species in solution, with 3–40 %wt H2O2 and for pH values above 9. DFT calculations of the peroxotellurate anion confirm its higher thermodynamic stability compared with those of the oxotellurate analogues. This is the first direct evidence for tellurium–peroxide coordination in any aqueous system and the first report of inorganic tellurium–peroxo complexes. General features common to all reported p‐block element peroxides could be discerned by the characterization of aqueous and crystalline peroxotellurates. 相似文献
17.
D.Y. Mikhaylov T.V. Gryaznova I.A. Litvinov O.G. Sinyashin 《Journal of organometallic chemistry》2009,694(24):3840-172
An efficient nickel-catalyzed method devoted to the direct addition of perfluoroalkyl halides (I, Br) to α-methylstyrene is described. This procedure allows for synthesis of compounds resulting from addition-dimerization in good yields. 相似文献
18.
Zatsepin AF Buntov EA Kortov VS Tetelbaum DI Mikhaylov AN Belov AI 《J Phys Condens Matter》2012,24(4):045301
Results of the investigation of photoluminescence (PL) mechanisms for silicon dioxide films implanted with ions of silicon (100 keV; 7 × 10(16) cm(-2)) and carbon (50 keV; 7 × 10(15)-1.5 × 10(17) cm(-2)) are presented. The spectral, kinetic and thermal activation properties of the quantum dots (Si, C and SiC) formed by a subsequent annealing were studied by means of time-resolved luminescence spectroscopy under selective synchrotron radiation excitation. Independent quantum dot PL excitation channels involving energy transfer from the SiO(2) matrix point defects and excitons were discovered. A resonant mechanism of the energy transfer from the matrix point defects (E' and ODC) is shown to provide the fastest PL decay of nanosecond order. The critical distances (6-9 nm) of energy transport between the bulk defects and nanoclusters were determined in terms of the Inokuti-Hirayama model. An exchange interaction mechanism is realized between the surface defects (E(s)'-centres) and the luminescent nanoparticles. The peculiarities of an anomalous PL temperature dependence are explained in terms of a nonradiative energy transfer from the matrix excitons. It is established that resonant transfer to the luminescence centre triplet state is realized in the case of self-trapped excitons. In contrast, the PL excitation via free excitons includes the stages of energy transfer to the singlet state, thermally activated singlet-triplet conversion and radiative recombination. 相似文献
19.
D. I. Tetelbaum A. N. Mikhaylov D. V. Guseinov A. I. Belov A. B. Kostyuk D. S. Korolev M. P. Fedonin D. A. Pavlov A. I. Bobrov D. E. Nikolitchev A. V. Boryakov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(4):681-687
Irradiation of fused quartz (SiO2) and sapphire (Al2O3) by Ne+ and F+ ions with medium energies and their subsequent annealing enables us to control the intensity and frequency of surface plasmon resonance in Au nanoparticles (NPs) synthesized in oxide matrices. The control process can be implemented because NPs dissolve during irradiation and undergo partial reconstruction at annealing. The degree of reconstruction depends on the matrix material and the type and dose of ions. It has been found that the difference in the results obtained by means of irradiation with ions with similar masses is substantially affected by the chemical nature of the ions. The composition, morphology, and structure of the unirradiated and irradiated layers are investigated by transmission electron microscopy, X-ray photoelectron spectroscopy, and spectroscopic ellipsometry. 相似文献
20.
A. N. Mikhaylov A. B. Kostyuk D. S. Korolev I. Yu. Zhavoronkov I. A. Chugrov A. I. Belov V. A. Burdov A. V. Ershov D. I. Tetelbaum 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(2):214-217
The possibility of ion beam formation of gold nanoparticles in SiO2 and Al2O3 matrices with presynthesized single-layer and
multi-layer ensembles of silicon nanocrystals is revealed by analyzing the spectra of optical transmission. The parameters
of gold nanoparticles are estimated. It is shown that luminescent properties of Si nanocrystals are preserved under irradiation
with gold ions. 相似文献