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71.
Ishikawa H Sugiyama M Baba I Setaka W Kira M Mikami N 《The journal of physical chemistry. A》2005,109(40):8959-8961
An equilibrium structure of the charge-transfer (CT) state of (p-cyanophenyl)pentamethyldisilane was determined by transient infrared absorption spectroscopy of its CH stretching vibration region, and by the spectral simulation with quantum chemical calculations. It was found that a pattern of the CH stretching vibration bands of the CT state is substantially different from that of the S0 state. This band feature of the CT state was well reproduced assuming the planar sigma(Si-Si)pi* state, where the disilanyl group and the phenyl ring lie in the same plane. Considering that the disilanyl group in the S0 and the locally excited pipi* states lie in the plane perpendicular to the phenyl ring, an occurrence of a twisting-type structural change during the ICT process was experimentally identified in the present study. 相似文献
72.
Mikami K Angelaud R Ding K Ishii A Tanaka A Sawada N Kudo K Senda M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(3):730-737
Asymmetric catalysts, prepared by chiral ligand exchange or chiral modification, can evolve further into highly activated catalysts through engineering with chiral activators. Two new methodologies for "super high-throughput screening" (SHTS) of chiral ligands and activators have been developed as a combination of HPLC-CD/UV (CD/ UV = circular dichroism/ultraviolet spectroscopy) or -OR/RIU (OR/RIU = optical rotation/refractive index unit) with a combinatorial chemistry (CC) factory. With these techniques, the % ee of the product is determined within minutes without separation of the enantiomeric products by using a nonchiral stationary phase. Therefore, those SHTS techniques combined with our 'asymmetric activation' concept can provide a powerful strategy for finding the best activated chiral catalyst. 相似文献
73.
Koarashi J. Mikami S. Akiyama K. Asano T. 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(3):569-572
A method using a system with two sampling units was proposed to determine the chemical forms of tritium (3H) released into the atmosphere from the Tokai Reprocessing Plant (TRP). The main advantage of the method is that no carrier gas is required for sampling in the case when air to be sampled has high specific activity with tritiated hydrogen (HT). Investigations using this method showed that 19.1–28.3% of total airborne 3H was released as HT from the TRP during reprocessing operation. No clear relation was found between the ratios of HT release and the types of spent fuel reprocessed.The authors would like to thank T. Yokota, K. Isaka, T. Kozawa and Y. Adachi of Inspection Development Company, Ltd., Y. Hiyama of Zuihou Sanyou Company Ltd., and K. Miyabe, T. Mizutani, H. Watanabe, M. Takeishi and K. Shinohara of Japan Nuclear Cycle Development Institute for their valuable assistance. 相似文献
74.
Takayuki Ebata Kei Saito Haruki Ishikawa Naohiko Mikami 《Research on Chemical Intermediates》1998,24(8):803-812
The S1−S0 electronic spectrum of methyl cinnamate in a supersonic jet has been investigated to discriminate the transitions of the
s-cis/s-trans conformers. Population labelling spectroscopy was applied to the conformer discrimination, and vibronic bands belonging to
each conformer were identified. The relative population was estimated from the fluorescence quantum yields obtained by lifetime
measurements. It was found that both conformers exist almost equally in a supersonic jet. The conformer identification of
the vibronic bands was carried out based on the difference of the red-shift of their hydrogen-bonded complexes with methanol. 相似文献
75.
We developed a new convenient method for generation of an abasic site at the 3'-terminus of an oligonucleotide. This method uses a 1-deaza-2'-deoxyguanosine residue, which easily undergoes depurination under acidic conditions. The abasic site of the oligonucleotide can be further modified with external functional groups. We report herein the chemical stability of 1-deaza-2'-deoxyguanosine in the oligodeoxynucleotide and the application to the postsynthetic modification of an oligonucleotide by utilizing the chemical property of 1-deaza-2'-deoxyguanosine. [Structure: see text] 相似文献
76.
77.
Yasushi Mikami 《International journal of quantum chemistry》1994,52(2):479-490
An efficient method for calculating electronic matrix elements for electron-transfer reactions in biological systems is proposed. We use the tight-binding model to describe the motion of one-electron in an array representing the system: donor (D), acceptor (A), and all other atoms that compose the protein. The matrix elements |TDA|;2 is evaluated at the estimated electron energy. The essential part of the method lies in the evaluation of the off-diagonal Green function 〈I|G|F〉 between the site I neighboring with the donor and the site F with the acceptor. The recursive residue generation method is used to evaluate 〈I|G|F|〉. As an application, these matrix elements in metal-labeled myoglobin are calculated and the results are compared with those evaluated with the renormalized-perturbation-expansion approach. © 1994 John Wiley & Sons, Inc. 相似文献
78.
The microsolvation structure of the [benzene-(methanol)(n)](+) (n = 1-6) clusters was analyzed by electronic and infrared spectroscopy. For the n = 1 and 2 clusters, further spectroscopic investigation was carried out by Ar atom attachment, which has been know as a useful technique for discriminating isomers of the clusters. The coexistence of multiple isomers was confirmed for the n = 1 and 2 clusters, and remarkably, preferential production of the specific isomers occurred in the Ar attachment. The most stable isomer of the n = 1 cluster was suggested to be of the "on-ring" structure where the nonbonding electrons of the methanol moiety directly interact with the pi orbital of the benzene cation moiety. This is a sharp contrast to [benzene-(H(2)O)(1)](+), exhibiting the "side" structure, where the water moiety is bound to the C-H sites of the benzene cation moiety. The structure of the n = 2 cluster was discussed with the help of density functional theory calculations. Spectral signatures of the intracluster proton-transfer reaction were found for n > or = 5. The intracluster electron-transfer reaction leading to the (methanol)(m)()(+) fragment was also seen upon vibrational and electronic excitation of n > or = 4. 相似文献
79.
Toshio Mikami 《随机分析与应用》2013,31(3):275-308
We prove exponential decays of probabilities of randomly perturbed dynamical systems in a d–dimensional Euclidean space Rd on time intervals which go to [0,∞] as the random fluctuation disappears. We also consider the exit problems when unperturbed dynamical systems are attracted to the inside of the domain under consideration 相似文献
80.