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212 results on '"Ishigure, Kenkichi"'

3. Ion beam induced crosslinking reactions in poly(di-n-hexylsilane)

Author

Seki, Shu, Maeda, Kensaku, Kunimi, Yoshihisa, Tagawa, Seiichi, Yoshida, Yoichi, Kudoh, Hisaaki, Sugimoto, Masaki, Morita, Yosuke, Seguchi, Tadao, Iwai, Takeo, Shibata, Hiromi, Asai, Keisuke, and Ishigure, Kenkichi

Subjects
Silane -- Research, Ion bombardment -- Usage, Crosslinked polymers -- Research, Chemicals, plastics and rubber industries
Abstract

Thin solid films of poly(di-n-hexylsilane) were irradiated with a number of high-energy ion beams, electron beams and 60Co gamma-rays of which linear energy transfer (LET) ranges from 0.2 to 1620 eV/nm. The beams induced nonhomogeneous reactions of crosslinking and main chain scissions in the films. A reaction model in a single ion track was applied for the crosslinking reactions. The expanding chemical track along an ion trajectory increased crosslinking G values.

Published
1999

4. Stability of radicals in aryl-substituted polysilanes with linear and planar silicon skeleton structures

Author

Seki, Shu, Cromack, Keith R., Trifunac, Alexander D., Yoshida, Yoichi, Tagawa, Seiichi, Asai, Keisuke, and Ishigure, Kenkichi

Subjects
Silane -- Analysis, Radicals (Chemistry) -- Analysis, Chemical equilibrium -- Analysis, Chemicals, plastics and rubber industries
Abstract

The stability of silyl radicals in solid-state poly(methylphenylsilane) (PMPS), PMPS containing structural defects and poly(phenylsilane) (PPS) with a silicon skeleton network has been studied. PMPS and phenyl-substituted PPS were subjected to 60Co gamma rays in the solid state. Results indicate that neutral silyl radicals in solid aryl-substituted polysilanes were found to be weaker than radicals obtained from dimethyl-substituted polysilanes. The radicals are stabilized by the defect in the silicon skeleton and the highly-branched silyl radicals have excellent stability.

Published
1998

10. An ESR study on solvated electrons in water and alcohols: Difference in the g factor and related analysis of the electronic state by MO calculation.

Author

Shiraishi, Hirotsugu, Ishigure, Kenkichi, and Morokuma, Keiji

Subjects
*ELECTRON paramagnetic resonance, *ELECTRONS, *WATER, *SPECTROMETERS
Abstract

An induction-detecting ESR spectrometer system, capable of μs time resolution, has been set up, and measurements were made on the radiolytically produced solvated electrons in water, methanol, ethanol, and mixtures of water and these alcohols. The spectrum of the solvated electron was a singlet in all these solvents. The g factor of the hydrated electron was measured to be 2.000 47±0.000 07 at 22 °C in reasonable agreement with the reported data. While this value is significantly smaller than the free electron g factor, the corresponding g factors in methanol and in ethanol, respectively 2.002 05±0.000 07 and 2.001 97±0.000 07 at 22 °C, were found much closer to it. In both methanol–water and ethanol–water mixtures the g factor of the solvated electron varied approximately in proportion to the mole fraction. The g shift of the hydrated electron was interpreted as arising from spin density in the proximity of oxygen nuclei of water molecules. Ab initio MO calculations were performed for an anionic cluster of water and that of methanol, assuming a cavity-like structure. The result showed that while in a water cluster the spin population on oxygen 2p atomic orbitals was in fact significant, the corresponding orbital spin population was smaller in a methanol cluster especially with a dipole-oriented model. The difference was considered to be related to increased diffuseness of the half-occupied orbital in the latter cluster. [ABSTRACT FROM AUTHOR]

Published
1988
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11. Study on radiation induced reactions in groundwater

Author

Katsumura, Yosuke and Ishigure, Kenkichi

Abstract

高レベル廃棄物の地層処分における健全性の確保のためには地下水の化学環境の把握が重要で、化学環境に及ぼす重要な因子として地下水の放射線誘起反応の検討が必要となる。本研究は地下水の化学環境への放射線影響の研究の第一歩として、水および、地下水に含まれる主要成分の放射線効果を、これまでの放射線化学分野で蓄積された知識を整理し、生ずる化学反応と、それらの反応速度定数などのデータベースを整備することを目的としている。さらに、これに基づき典型的な条件下でシミュレーションを行うとともに、今後、研究すべき反応や実験について検討した。特に、実験データの蓄積とシミュレーションとの比較が必要と結論された。, In order to keep the integrity of the repository of the radioactive high level waste, it is inevitably important to grasp and clarify the chemical conditions of the groundwater and it is highly required to evaluate the radiation induced chemical effect in groundwater. In the present report, a database has been constructed from the literatures in the field of radiation chemistry published up to now, as a first step of the evaluation of the radiation induced chemical reactions and their rate constants in aqueous solutions containing chemical species, which are normally present in groundwater. On the basis of the database, simulations for several typical aqueous solutions have been carried out, and both further reactions to be investigated and additional experiments to be done in future have been pointed out. It is concluded that experimental data is highly expected to be accumulated and compared with simulation.

Published
1995

12. Reduction potential of the nitrate radical in aqueous solution

Author

Pei-Yun Jiang, Katsumura, Yosuke, Ishigure, Kenkichi, and Yoshida, Yoichi

Subjects
Nitrates -- Research, Radicals (Chemistry) -- Research, Radiation chemistry -- Research, Chemistry
Abstract

The pulse radiolysis of nitric acid solutions resulted in the conversion of the hydroxyl radical into the nitrate radical until equilibrium was established. Attainment of equilibrium was found to be more rapid for acid solutions with concentrations over 0.5 M. Formation of the nitrate radical proceeded via first-order kinetics for 0.5 to 1.5 M nitric acid solutions, while formation of the radical in 0.2 M and 0.3 M was inadequate due to the decay of the hydroxyl and nitrate radicals during the establishment of equilibrium.

Published
1992

17. A New Catalyst for Selective Oxidation of CO in H2: Part 1, Activation by Depositing a Large Amount of FeOxon Pt/Al2O3and Pt/CeO2Catalysts

Author

Tanaka, Ken-ichi, primary, Moro-oka, Yoshihiko, additional, Ishigure, Kenkichi, additional, Yajima, Tatsuhiko, additional, Okabe, Yosio, additional, Kato, Yoshinobu, additional, Hamano, Haruo, additional, Sekiya, Shu-ichi, additional, Tanaka, Hiroto, additional, Matsumoto, Yuji, additional, Koinuma, Hideomi, additional, He, Hong, additional, Zhang, Changbin, additional, and Feng, Qingcai, additional

Published
2004
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24. Determination of Third-Order Optical Nonlinearity Dispersion of 1-Methyl-1′-Octadecyl-2,2′-Cyanine Perchlorate Langmuir-Blodgett Films Using Electroabsorption Spectroscopy

Author

Hidetoshi Murakami, Hidetoshi Murakami, primary, Ryuji Morita, Ryuji Morita, additional, Takashi Watanabe, Takashi Watanabe, additional, Keisuke Asai, Keisuke Asai, additional, Itaru Honma, Itaru Honma, additional, Haoshen Zhou, Haoshen Zhou, additional, Mikio Yamashita, Mikio Yamashita, additional, Kenkichi Ishigure, Kenkichi Ishigure, additional, and Hidemi Shigekawa, Hidemi Shigekawa, additional

Published
2000
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