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41.
O. G. Poluektov L. M. Utschig J. Tang A. A. Dubinski S. Schlesselman M. C. Thurnauer 《Applied magnetic resonance》2001,21(3-4):311-323
Time-resolved high-frequency electron paramagnetic resonance (EPR) spectroscopy was applied to study the structure and dynamics of the electron transfer pathways in the photosynthetic RC proteins. When the spin-polarized EPR spectra are recorded at the high field, the singlet-triplet mixing in the radical pairs becomes faster due to the increase of Zeeman interaction, and a sequential electron transfer polarization model, which includes both the primary and secondary radical pairs, should be considered. Application of the sequential electron transfer polarization model for the interpretation of the bacterial RC proteins with a “slow” electron transfer rate reveals the importance of the protein dynamics. It was shown that the reorganization energy for the electron transfer process between P 865 + H?QA and P 865 + HQ A ? , but not the change in the structure of the donor-acceptor complex, is a dominant factor that alters the electron transfer rate. The relaxation data, obtained in the delay after laser flash experiment, have been used to estimate the magnetic interaction in the weakly coupled radical pair. High-frequency spin-polarized EPR spectra allow the quantitative characterization of isotopically labeled quinone exchange in the PS I reaction center proteins. 相似文献
42.
Ligand Transformations and Efficient Proton/Water Reduction with Cobalt Catalysts Based on Pentadentate Pyridine‐Rich Environments 下载免费PDF全文
Debashis Basu Dr. Shivnath Mazumder Xuetao Shi Habib Baydoun Dr. Jens Niklas Dr. Oleg Poluektov Prof. H. Bernhard Schlegel Prof. Cláudio N. Verani 《Angewandte Chemie (International ed. in English)》2015,54(7):2105-2110
A series of cobalt complexes with pentadentate pyridine‐rich ligands is studied. An initial CoII amine complex 1 is prone to aerial oxidation yielding a CoIII imine complex 2 that is further converted into an amide complex 4 in presence of adventitious water. Introduction of an N‐methyl protecting group to the ligand inhibits this oxidation and gives rise to the CoII species 5 . Both the CoIII 4 and CoII 5 show electrocatalytic H2 generation in weakly acidic media as well as in water. Mechanisms of catalysis seem to involve the protonation of a CoII? H species generated in situ. 相似文献
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Bondar Alex Dolgov Alexander Poluektov Anton Vorobiev Vitaly 《The European Physical Journal C - Particles and Fields》2013,73(6):1-6
The European Physical Journal C - We study a possible fate of universe, one in which there is neither a rip singularity, which results in the disintegration of bound systems, nor an endless... 相似文献
45.
The effect of CHCl3 vapor on rare-earth metal vapors in an acetylene-air flame has been studied spectroscopically. It has been established that both the molecular spectra of the oxide molecules and the emission spectra of the atoms (Eu, Yb) are weakened in the presence of this vapor. In the case of europium and lutecium, the spectra contain new (chloride molecule) bands. Investigation of the relationship between the emission intensities of the atoms or molecules and the partial pressure of chlorine in the flame suggests that molecules of the MeCl2 type are formed in the flame. 相似文献
46.
A constant or alternating electric field applied to graphite electrodes affects the absorption of light by alkali metal atoms in a flame and also the emission intensity. The weakening of the atomic absorption of potassium, rubidium, and cesium near the cathode has been studied both over the width (between the electrodes) and over the height (along the electrode and higher). The effect is connected with the fall in the partial pressure of the metal atoms resulting from a shift of the ionization equilibrium to the right. 相似文献
47.
O. G. Poluektov L. M. Utschig M. C. Thurnauer G. Kothe 《Applied magnetic resonance》2007,31(1-2):123-143
Electron paramagnetic resonance (EPR) and related spectroscopic tools remain among the most important probes of structure and function of natural photosynthetic systems. Indeed, the challenging questions in the study of photosynthesis have to a great extent dictated the directions taken in the development of EPR and associated spectroscopies. In this overview we demonstrate, with recent examples from our laboratories, the potential of high-frequency and time-resolved EPR spectroscopy to reveal unique information about electron transfer processes and the structure of photosynthetic systems. A common feature of these experiments is that they probe hyperfine interactions of the spincorrelated radical pair. Thus, the analysis of the results requires consideration of three interacting spins: two correlated electron spins with one nuclear spin. The results illustrate the importance of resolving nuclear hyperfine structure for obtaining details of structure-function relationships in photosynthetic electron transfer. 相似文献
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The possibility of recovery of contaminants (soaps of resin and fatty acids, Leukanol, and finely dispersed rubber) from spent synthetic ion-exchange resins in the stage of treatment of wastewater formed in production of synthetic rubbers and latexes, which polymer composites obtained, was studied. 相似文献
50.
Dimitrijevic NM Vijayan BK Poluektov OG Rajh T Gray KA He H Zapol P 《Journal of the American Chemical Society》2011,133(11):3964-3971
Using the electron paramagnetic resonance technique, we have elucidated the multiple roles of water and carbonates in the overall photocatalytic reduction of carbon dioxide to methane over titania nanoparticles. The formation of H atoms (reduction product) and (?)OH radicals (oxidation product) from water, and CO(3)(-) radical anions (oxidation product) from carbonates, was detected in CO(2)-saturated titania aqueous dispersion under UV illumination. Additionally, methoxyl, (?)OCH(3), and methyl, (?)CH(3), radicals were identified as reaction intermediates. The two-electron, one-proton reaction proposed as an initial step in the reduction of CO(2) on the surface of TiO(2) is supported by the results of first-principles calculations. 相似文献