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281.
Ishikawa H Sugiyama M Setaka W Kira M Mikami N 《Physical chemistry chemical physics : PCCP》2007,9(1):117-126
The solvent reorientation dynamics of the intramolecular charge-transfer (ICT) process of the (p-cyanophenyl)pentamethyldisilane-H(2)O (CPDS-H(2)O) cluster was investigated by transient infrared (IR) absorption spectroscopy. Transient IR bands of two distinct charge-transfer (CT) states appeared in both the OH and the CN-stretching vibration regions. Analyses of the IR spectra and the time profiles of the transient bands revealed that the ICT process of the CPDS-H(2)O cluster proceeds in two steps. The first step is a transition from a photo-prepared locally excited (LE) state to the CT state, which is accompanied by a minor reorientation of the H(2)O moiety. In contrast, the second step is an extensive reorientation process of the H(2)O molecule in the CT state. These two reorientation processes exhibit very distinct pico- and nano-second time scales. In the latter case, a relatively slow time constant of 2 ns was related to a large geometric change in the orientation. 相似文献
282.
Infrared spectra of completely size-selected protonated water clusters H+(H2O)n are reported for clusters ranging from n=15 to 100. The behavior of the dangling OH stretch bands shows that the hydrogen bond structure in H+(H2O)n is uniquely different to that of (H2O)n up to the size of n=100, at least. This finding indicates that the presence of an excess proton creates a characteristic morphology in the hydrogen bond network architecture of more than 100 surrounding water molecules. 相似文献
283.
Kazutoshi Shindo Kanae Mikami Shinichi Takaichi Norihiko Misawa 《Tetrahedron letters》2007,48(15):2725-2727
A novel acyl glyco-carotenoic acid, diapolycopenedioic acid xylosyl ester, was isolated from a marine bacterium Rubritalea squalenifaciens belonging to subdivision 1 of Verrucomicrobia as the major red pigment by using chromatographic methods. The structure of diapolycopenedioic acid xylosyl ester was determined to be 4-[2-O-(12-methyltridecanoyl)-β-xylopyranosyl] hydrogen 4,4′-diapo-ψ,ψ-carotene-4,4′-dioate by analysis of the MS and NMR data for this acid and for the diacetyl diapolycopenedioic acid xylosyl ester. The diapolycopenedioic acid xylosyl ester showed potent antioxidative activity against a lipid peroxidation model. 相似文献
284.
Mikami S Fujita K Nakamura T Yorimitsu H Shinokubo H Matsubara S Oshima K 《Organic letters》2001,3(12):1853-1855
[see reaction]. A gallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source. 相似文献
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287.
The absorption and fluorescence spectra of pyrazine have been observed in vapor, solution and crystal, and the vibrational structures have been analyzed in detail. The fluorescence spectrum consists of long progressions of the nontotally symmetric vibration ν5(b2g), and the absorption spectrum contains also the progression of the corresponding excited state vibration ν′5(b2g. However, the pattern of the latter progression is unusual because of the highly anharmonic nature of the potential of the 1B3u state, which may be expressed by a functional form containing a quadratic term in the normal coordinate. All the experimental results suggest that the known vibronic interaction between the state and the state through the vibration ν2(b2g) is strong. The vibronic coupling and the potential of the 1B3u state were found to be very sensitive to solvent. 相似文献
288.
Ko Mibu Kazuaki Mikami Masaaki Tanaka Ryo Masuda Yoshitaka Yoda Makoto Seto 《Hyperfine Interactions》2017,238(1):92
The Morin transition of very thin Ir-doped α-Fe2O3 films, which is not detectable with conventional magnetization measurements, was studied by conversion electron Mössbauer spectroscopy using a 57Co source and nuclear resonant scattering using a synchrotron light source. It was found that (i) the Morin transition temperature increases as the Ir ratio increases, (ii) it decreases when the film thickness decreases, and (iii) the transition becomes irreversible when Ir ratio is small and the thickness is thin. These tendencies were found reproducible and systematic, although the mechanisms are to be clarified by further studies. 相似文献
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