研究者データベース

小泉 均(コイズミ ヒトシ)
工学研究院 応用化学部門 機能材料化学分野
准教授

基本情報

所属

  • 工学研究院 応用化学部門 機能材料化学分野

職名

  • 准教授

学位

  • 理学博士(東京工業大学)

J-Global ID

研究キーワード

  • 工業物理化学   機能・物性・材料   Other Materials   Properties and Materials in Chemistry   Function   

研究分野

  • ナノテク・材料 / 機能物性化学
  • ナノテク・材料 / 基礎物理化学

職歴

  • 2007年03月 - 現在 北海道大学 工学研究院物質化学部門 准教授
  • 1997年10月 - 2007年03月 北海道大学
  • 1984年10月 - 1997年09月 北海道大学 工学部 助手
  • 1990年10月 - 1991年09月 ハーン・マイトナー研究所 客員研究員
  • 1984年04月 - 1984年09月 東京工業大学 理工学研究科 日本学術振興会博士課程奨励研究員

学歴

  • 1980年04月 - 1984年09月   東京工業大学   理工学研究科   化学専攻
  •         - 1982年   東京工業大学
  • 1976年04月 - 1980年03月   東京工業大学   理学部   化学科
  •         - 1980年   東京工業大学

所属学協会

  • 高分子学会   日本放射線化学会   応用物理学会   日本化学会   

研究活動情報

論文

  • Hiroki Ohta, Hitoshi Koizumi
    POLYMER BULLETIN 74 6 2319 - 2330 2017年06月 [査読有り][通常論文]
     
    Roles of singlet oxygen (O-1(2)) in photo-induced degradation of poly(3-hexylthiophene) (P3HT) and poly(3-hexyloxythiophene) (P3HOT) were examined. The results indicate that O-1(2) has a considerable role in the degradation of P3HT and P3HOT. Photo-irradiation of P3HT in air resulted in the reduction of the pi-conjugation. The photo-induced reduction also occurred for P3HOT, and it was much faster than that of P3HT. Manceau et al. have reported that O-1(2) was generated by photo-irradiation of P3HT in the presence of oxygen and, nevertheless, O-1(2) is not the principal photo-oxidative degradation intermediate of P3HT (Manceau et al., Macromol Rapid Commun 29:1823-1827, 2008). However, exposures of solid P3HT and P3HOT to chemically generated O-1(2) provided decreases in the pi pi*absorption in our study. The decrease for P3HOT was much larger than that for P3HT. The exposure of P3HOT showed the formation of polarons. The difference in P3HT and P3HOT for the effects of the photo-irradiation and of O-1(2) will be ascribed to the difference in their ionization potentials.
  • Takayuki Nakanishi, Yuki Suzuki, Yoshihiro Doi, Tomohiro Seki, Hitoshi Koizumi, Koji Fushimi, Koji Fujita, Yukio Hinatsu, Hajime Ito, Katsuhisa Tanaka, Yasuchika Hasegawa
    INORGANIC CHEMISTRY 53 14 7635 - 7641 2014年07月 [査読有り][通常論文]
     
    The effective magneto optical properties of novel nonanuclear Tb(III) complexes with Tb-O lattice (specifically, [Tb-9(sal-R)(16)(mu-OH)(10)]+NO3-, where sal-R = alkyl salicylate (R = -CH3 (Me), -C2H5 (Et), -C3H7 (Pr), or -C4H9 (Bu)) are reported. The geometrical structures of these nonanudear Tb(III) complexes were characterized using X-ray single-crystal analysis and shape-measure calculation. Optical Faraday rotation was observed in nonanuclear Tb(III) complexes in the visible region. The Verdet constant per Tb(III) ion of the Tb-9(sal-Me) complex is 150 times larger than that of general Tb(III) oxide glass. To understand their large Faraday rotation, electron paramagnetic resonance measurements of Gd(III) complexes were carried out. In this Report, the magneto optical relation to the coordination geometry of Tb ions is discussed.
  • Yasuchika Hasegawa, Masashi Maeda, Takayuki Nakanishi, Yoshihiro Doi, Yukio Hinatsu, Koji Fujita, Katsuhisa Tanaka, Hitoshi Koizumi, Koji Fushimi
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 135 7 2659 - 2666 2013年02月 [査読有り][通常論文]
     
    Novel EuS nanocrystals containing paramagnetic Mn(II), Co(II), or Fe(II) ions have been reported as advanced semiconductor materials with effective optical rotation under a magnetic field, Faraday rotation. EuS nanocrystals with transition-metal ions, EuS:M nanocrystals, were prepared by the reduction of the Eu(III) dithiocarbamate complex tetraphenylphosphonium tetrakis(diethyldithiocarbamate)europium(III) with transition-metal complexes at 300 degrees C. The EuS:M nanocrystals thus prepared were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectroanalysis (ICP-AES), and a superconducting quantum interference device (SQUID) magnetometer. Enhanced Faraday rotations of the EuS:M nanocrystals were observed around 550 nm, and their enhanced spin polarization was estimated using electron paramagnetic resonance (EPR) measurements. In this report, the magneto-optical relationship between the Faraday rotation efficiency and spin polarization is discussed.
  • Yoshinori Aoyama, Kouji Hatakeyama, Takuma Mukai, Hitoshi Koizumi
    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 86 1 51 - 56 2013年01月 [査読無し][通常論文]
     
    Poly(3-alkylthiophene) (P3AT) with alkyl side chains longer than or equal to butyl is soluble in some solvents and fusible. However, conductive states of P3AT are unstable. In order to develop soluble conductive polymers with a stable conductive state, electronic properties of poly[3-(1,1-dimethylpropyl)thiophene] (P3DMPT) and poly(3-cyclohexylthiophene) (P3cHT) were compared with those of poly(3-octylthiophene) (P3OT). The photoabsorption spectrum of P3DMPT did not change before and after doping with NOBF4. This is due to its high oxidation potential. The oxidation peak in the cyclic voltammogram of P3DMPT was 1.65 V vs. Ag/Ag+, which is too high to be doped with NOBF4. Polaron peaks were observed after the doping of P3cHT. The polarons of P3cHT decayed faster than those of P3OT with time. However, the behavior of the electron spin resonance spectrum of P3cHT was different from that of P3OT: the spin concentration of P3cHT decreased, whereas the spin concentration of P3OT increased with time. The conductive state of P3cHT will decay through different mechanism of P3OT: their dedoping will be a reverse process of doping. The reverse dedoping processes of P3cHT will be due to the high oxidation potentials of P3cHT.
  • 小泉 均
    工学教育 60 4 20 - 25 日本工学教育協会 2012年07月20日 [査読無し][通常論文]
     
    Elementary textbooks on quantum chemistry published for the last dozen years in Japanwere surveyed. In the most of the textbooks, Heitler-London theory or simple linear atomiccombination-molecular orbital theory is still used to explain the nature of the chemical bond of a hydrogen molecule, which theories were criticized in 1960s. Physical meanings on several problemsthat many students may have questions were not described in these books. Some of the problemswere answered in this paper. Desirable textbooks on quantum chemistry which fit with times wereproposed.
  • Akihiro Ishigaki, Hitoshi Koizumi
    RADIATION PHYSICS AND CHEMISTRY 81 7 803 - 806 2012年07月 [査読無し][通常論文]
     
    In order to develop a new synthetic method and to study mechanism of oxidative polymerization of conducting polymers, polymerization of 3-octylthiophene in several organic solvents by gamma-irradiation was examined. Polymers bimodal distribution with molecular weights at 500-1000 and 2000-3000 were generated by the irradiation of chloroform solutions. The values of monomer conversion (G( - M)) decreased from 445 to 10 with doses from 0.99 kGy to 594 kGy. The large G( - M) values and dose dependence of G( - M) cannot be explained with widely accepted mechanism for electrochemical polymerization or chemical oxidative polymerization. Another mechanism, which proceeds through chain reactions, is proposed. This mechanism explains the large G( - M) and the dependence on the dose. (C) 2012 Elsevier Ltd. All rights reserved.
  • Masatake Ozawa, Kazue Tani, Masaki Tachibana, Hitoshi Koizumi, Nobutoshi Kiba
    CHROMATOGRAPHIA 72 3-4 313 - 316 2010年08月 [査読有り][通常論文]
     
    The retention behavior of purine and purine-like compounds on titania was investigated in order to elucidate the strong retention of purine on titania. It was verified that, as expected, the strong retention stemmed from the formation of a chelate ring using the two nitrogen atoms N3 and N9 with titania. Purine has two possible tautometric forms because of proton tautomerism between N7 and N9. Hence, the lone pair of either of the two nitrogen atoms could be located immediately in an sp(2) orbital. Therefore, it was found that the lone pairs of N3 and N9 must be located in an sp(2) orbital, and the location is essential to forming the chelate with titania. Moreover, the effect of the presence of methanol and acetonitrile in the mobile phase on retention was also investigated. The retention strength increased with their content, but the tendency of this increase was different for the two organic solvents. It was concluded that the difference stems from the differing degrees of strength of the ligands, which includes the analytes and the solvents, as a result of competing with each other. Water and methanol acted as ligands strong enough to compete with the analytes, but acetonitrile did not, probably because it lacks hydroxy groups, which have a strong affinity for titania.
  • Ozawa Masatake, Tani Kazue, Nomura Ai, Tachibana Masaki, Koizumi Hitoshi, Kiba Nobutoshi
    CHROMATOGRAPHIA 70 3-4 533 - 537 2009年08月 [査読有り][通常論文]
  • HATAKEYAMA Kouji, KOIZUMI Hitoshi, ICHIKAWA Tsuneki
    Bull Chem Soc Jpn 82 2 202-205 (J-STAGE) - 205 2009年02月15日 [査読有り][通常論文]
  • Takahide Kimura, Hitoshi Koizumi, Tsuneki Ichikawa
    SURFACE & COATINGS TECHNOLOGY 201 19-20 8506 - 8510 2007年08月 [査読有り][通常論文]
     
    Vapor deposition of decacyclene, a polycyclic aromatic compound, under vacuum on a flat plate resulted in rapid formation of cylindrical decacyclene whiskers with a layered structure and with lengths and uniform diameters of 1-20 mu m and 20-100 nm, respectively. The whiskers were converted to conducting amorphous carbon nanofibers by ion-beam irradiation at ambient temperature. Observation of the SEM images of the whiskers revealed that the growing whiskers were floated on the surfaces of supercooled decacyclene liquid droplets, and the diameter of each whiskers were kept constant during the growth by attractive and repulsive interactions between the liquid and surfaces of the whiskers parallel and perpendicular to the layer, respectively. Cyclic voltammetry of the carbon nanofibers in 1 mol/dm(3) Na2SO4 showed the electrical capacitance of 41 F/g, which is comparable to the capacitance of various activated carbon fibers. (C) 2007 Elsevier B.V. All rights reserved.
  • Takahide Kimura, Hiroshi Kinoshita, Hitoshi Koizumi, Tsuneki Ichikawa
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 255 2 321 - 325 2007年02月 [査読有り][通常論文]
     
    The micropatterns and nanostructures of conducting carbonaceous materials were generated by ion beam-irradiation of several polycyclic aromatic compounds that were rapidly evaporated onto substrates under vacuum. Evaporation of the compounds gave either smooth films by direct crystallization of the vapors onto substrates or rugged films by condensation of the vapors onto substrates followed by the crystallization. Ion beam-irradiation of the resultant films caused the development of inter- and intra-molecular aromatic rings accompanying the detachment of hydrogen and hetero atoms. Irradiation with a 200 keV N+ ion beam to a dose of more than 10(16) ions/cm(2) converted the films to carbonaceous materials with the electrical conductivity comparable to graphite. A desired micropattern of conducting carbon was obtained by irradiating the films through a mask. Irradiation of the rugged films of 1-aminoanthraquinone, acenaphthenequinone and 2,4,6-tri(2-pyridyl)-1,3,5-triazine caused significant volume contraction that was induced by the detachment of hetero atoms. The contraction proceeded while keeping inter-molecular connections with each other, so that the resultant films showed high surface area with nanoscale carbon networks. (c) 2006 Elsevier B.V. All rights reserved.
  • Takahide Kimura, Hitoshi Koizumi, Hironobu Kinoshita, Tsuneki Ichikawa
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 46 2 703 - 707 2007年02月 [査読有り][通常論文]
     
    Rapid vapor deposition of decacyclene, a polycyclic aromatic compound, on any substrate except for graphite has been found to produce cylindrical nanowires of decacyclene with uniform diameters of 40-70 mu m and lengths of 1-10 mu m that are further converted to conducting carbon nanofibers by ion beam irradiation. Detailed observation of the nanowires prepared under various conditions reveals that the nanowires brow on the surface of supercooled liquid droplets that are generated on the substrate by rapid condensation of decacyclene vapor. The nanowires grow toward the vacuum while keeping the growth plane beneath the surface. A controlling factor that keeps the diameter of each nanowire constant is the difference of the wettability between the growth plane and the lateral wall of the nanowire. Although the growth plane is always attached to the liquid due to the attractive interaction with the liquid, because of the repulsive interaction of the lateral wall with the liquid, the growing layer starts to emerge from the surface once the growing layer entirely covers the overlaying layer. The radial growth is very fast at the initial stage of nanowire formation, so that the diameter of the growing layer Successively increases until the maximum diameter is attained. The nanowire is therefore cylindrical with a hemispherical tip.
  • Hitoshi Koizumi, Yuki Itoh, Tsuneki Ichikawa
    CHEMISTRY LETTERS 35 12 1350 - 1351 2006年12月 [査読有り][通常論文]
     
    Microwave-assisted synthesis of 4-methyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one by the condensation of 1,2-phenylene-diamine and ethyl acetoacetate was examined. The yields were compared with those by classical heating under various conditions. The yield is mainly determined by the temperature of the reaction mixtures, and little affected by the difference in the heating methods. Nonthermal effects in microwave heating have not been observed.
  • H Koizumi, H Dougauchi, T Ichikawa
    JOURNAL OF PHYSICAL CHEMISTRY B 109 32 15288 - 15290 2005年08月 [査読無し][通常論文]
     
    To clarify the mechanism of thermal dedoping processes of conducting poly(3-alkylthiophenes), temporal changes in electric conductivity, photoabsorption, and electron spin resonance of iodine-doped poly(3-octylthiophene) were examined. A decrease in the electric conductivity was accompanied by a decrease in the photoabsorption of the polymer cation and an increase in the spin concentration: the cation is a spinless charge carrier and it was converted to an immobile paramagnetic species. The conversion proceeds through deprotonation of the cation, which results in the formation of a polyenyl radical.
  • H Koizumi, H Dougauchi, T Ichikawa
    JOURNAL OF PHYSICAL CHEMISTRY B 109 32 15288 - 15290 2005年08月 [査読無し][通常論文]
     
    To clarify the mechanism of thermal dedoping processes of conducting poly(3-alkylthiophenes), temporal changes in electric conductivity, photoabsorption, and electron spin resonance of iodine-doped poly(3-octylthiophene) were examined. A decrease in the electric conductivity was accompanied by a decrease in the photoabsorption of the polymer cation and an increase in the spin concentration: the cation is a spinless charge carrier and it was converted to an immobile paramagnetic species. The conversion proceeds through deprotonation of the cation, which results in the formation of a polyenyl radical.
  • H Koizumi, H Dougauchi, T Ichikawa
    JOURNAL OF PHYSICAL CHEMISTRY B 109 32 15288 - 15290 2005年08月 [査読有り][通常論文]
     
    To clarify the mechanism of thermal dedoping processes of conducting poly(3-alkylthiophenes), temporal changes in electric conductivity, photoabsorption, and electron spin resonance of iodine-doped poly(3-octylthiophene) were examined. A decrease in the electric conductivity was accompanied by a decrease in the photoabsorption of the polymer cation and an increase in the spin concentration: the cation is a spinless charge carrier and it was converted to an immobile paramagnetic species. The conversion proceeds through deprotonation of the cation, which results in the formation of a polyenyl radical.
  • T Kimura, H Koizumi, H Kinoshita, T Ichikawa
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 236 474 - 481 2005年07月 [査読無し][通常論文]
     
    Amorphous carbon nanofibers with lengths of 1-20 mu m, uniform diameters of 20-100 nm were generated by ion beam-irradiation of decacyclene whiskers that were prepared on a flat plate of any material during vapor-deposition of decacyclene, a polycyclic aromatic compound, in vacuum for only a few minutes. The length of the whiskers did not depend on the duration of the vapor-deposition, whereas the number density of the whiskers increased with increasing the duration and reached 6.9 x 10(7) cm(-2) at 4.5 min after starting the vapor-deposition. Irradiation of more than 10(16) ions/cm(2) with a 200 keV N+ ion beam converted the whiskers to carbon nanofibers with the electrical conductivity comparable to that of graphite. This novel method of preparation is advantageous for aligning the fibers on a desired location, since the fibers are generated only on the irradiated part at ambient temperature without catalyst. (c) 2005 Elsevier B.V. All rights reserved.
  • T Kimura, H Koizumi, H Kinoshita, T Ichikawa
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 236 1-4 474 - 481 2005年07月 [査読無し][通常論文]
     
    Amorphous carbon nanofibers with lengths of 1-20 mu m, uniform diameters of 20-100 nm were generated by ion beam-irradiation of decacyclene whiskers that were prepared on a flat plate of any material during vapor-deposition of decacyclene, a polycyclic aromatic compound, in vacuum for only a few minutes. The length of the whiskers did not depend on the duration of the vapor-deposition, whereas the number density of the whiskers increased with increasing the duration and reached 6.9 x 10(7) cm(-2) at 4.5 min after starting the vapor-deposition. Irradiation of more than 10(16) ions/cm(2) with a 200 keV N+ ion beam converted the whiskers to carbon nanofibers with the electrical conductivity comparable to that of graphite. This novel method of preparation is advantageous for aligning the fibers on a desired location, since the fibers are generated only on the irradiated part at ambient temperature without catalyst. (c) 2005 Elsevier B.V. All rights reserved.
  • T Kimura, H Koizumi, H Kinoshita, H Takahashi, T Ichikawa
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 43 7A L862 - L864 2004年07月 [査読無し][通常論文]
     
    Cabon nanofibers (CNFs) were synthesized at room temperature without a catalyst by the ion beam irradiation of an aromatic compound: CNFs with a length of 1-10 mum and a diameter of approximately 100 nm were generated by the irradiation of decacyclene with 200 keV He+ or N+ ions. The number density and length of the CNFs depend on the fluence and species of the ions. Observations by transmission electron microscopy indicate that the CNFs were amorphous.
  • Jpn. J. Appl. Phys. 43(1), 347-348 2004年 [査読無し][通常論文]
  • H Koizumi, H Dougauchi, T Yamano, T Ichikawa
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 42 11 7122 - 7123 2003年11月 [査読無し][通常論文]
     
    Poly(3-octylthiophene) was irradiated with X-rays in atmospheres of CH3Br, SF6, and N2O gases. The electrical conductivity was increased after the irradiations. The electrical conductivity was also increased by irradiating the gases near the polymer film without irradiating the film itself. This result indicates that dopants were generated upon irradiation in the gas phase and the polymer was doped through reactions of the dopants with the polymer. The radiation-induced doping effects were also observed for poly(3-octylthiophene) coated with solid 1,2,5,6,9,10-hexabromocyclododecane.
  • KOIZUMI Hitoshi
    放射線化学 76 21 - 25 2003年09月05日 [査読無し][通常論文]
  • H Koizumi, M Taguchi, Y Kobayashi, T Ichikawa
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 208 5 161 - 165 2003年08月 [査読無し][通常論文]
     
    Gelation of polydimethylsiloxane irradiated with 256 MeV Ar, 306 MeV Ne and 204 MeV C ions was examined. The insoluble residue of the irradiated polydimethylsiloxane was separated with membrane filters. The weight of the insoluble residue was proportional to the number of irradiated ions. This result indicates that gelation occurs in the high local dose region in the ion tracks. A gel string is generated in each ion track. The yield of the insoluble residue depends on the ion beams. The radius of the gel strings estimated using the G-value of crosslinking for low-LET radiation and with appropriate dose distributions in the ion tracks agrees with the experimental results. (C) 2003 Elsevier B.V. All rights reserved.
  • H Koizumi, K Kitamura, T Ichikawa
    JOURNAL OF PHYSICAL CHEMISTRY B 107 24 5773 - 5776 2003年06月 [査読無し][通常論文]
     
    Decay of ions trapped in gamma-irradiated poly(methyl methacrylate) (PMMA)-containing ion scavengers was examined. Cations in PMMA migrate through diffusion and by a hopping transfer of the charge. They encounter anions, combine, and thereby decay. The diffusion of cations was confirmed by a comparison of decay of ions in PMMA-containing pyrene and that in a copolymer of methyl methacrylate and I-pyrenylmethyl metbacrylate. Cations in the former sample decay faster than those in the latter sample. The ions in the copolymer are chemically bonded to the polymer chains, preventing the diffusion of the ions. However, the dependence of the decay of the ions on the concentration of pyrenyl groups indicated that the ions decay through a hopping transfer of the charge on pyrenyl groups. The hopping transfer was suppressed by triphenylamine. The suppression is ascribed to structural difference in neutral triphenylamine and its cation. Anions in PMMA are ketyl-type anions at the side chains of the polymer. Their migration is suppressed, since they are connected to the polymer chains and the structures of the neutral state and its anion are different.
  • H Koizumi, T Ichikawa, M Taguchi, Y Kobayashi, H Namba
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 206 13 1124 - 1127 2003年05月 [査読無し][通常論文]
     
    Effects of ion beam irradiation on alpha-alanine, adipic acid and polydimethylsiloxane were examined. Stable radicals were generated in the radiolysis of solids of alpha-alanine and adipic acid by gamma-ray, 220 MeV C ions, 350 MeV Ne ions and 175 MeV Ar ions. The G-value decreases in this order. The G-value for adipic acid decreases more than that for alpha-alanine. The decreases in the G-value are ascribed to high local dose in the ion tracks. Effective G-value of the radicals for gamma-irradiations decreases at high doses. The local dose in the ion tracks exceeds those doses, and the G-values for the ion irradiation are hence smaller than the G-value for gamma-irradiations. The difference in the dependence of the G-values for alpha-alanine and adipic acid on the ion beams is due to difference in the dose-yield relationship for radical formation. The high local dose in the ion tracks exceeds the gelation dose of some of polymers. Formation of gel strings of polydimethylsiloxanes generated in heavy ion tracks was observed by atomic force microscopy. (C) 2003 Elsevier Science B.V. All rights reserved.
  • H Koizumi, T Sasaki, T Ichikawa
    RADIATION RESEARCH 158 2 241 - 246 2002年08月 [査読有り][通常論文]
     
    Chain reactions in gamma-irradiated 2-propanol solutions of diphenyliodonium salts have been studied. Protonic acids were generated in the irradiated solutions with high yields, whereas acid formation as a result of thermal reactions was negligible. The solution can be used as a high-sensitivity chemical dosimeter. The G value of acidic protons increases with increasing concentration of diphenyliodonium salt at the lower concentrations because the reaction rate of a propagation reaction increases. However, the chain is limited by a termination reaction between phenyl radical and the iodonium salt: The G value shows a maximum value of 610 mumol J(-1) at the concentration of 0.08 mol dm(-3) and decreases at higher salt concentrations. (C) 2002 by Radiation Research Society.
  • J. Nucl. Sci. Tech. 39(8) 880-884 2002年 [査読無し][通常論文]
  • Chem. Phys Letters 363(1 2) 13-17 2002年 [査読無し][通常論文]
  • Radiat. Res. 158(2), 241-246 2002年 [査読無し][通常論文]
  • Nucl. Instrm. and Meth. B 179 4 530 - 535 2001年 [査読無し][通常論文]
  • Chem. Phys. Letters. 340 3-4 256 - 260 2001年 [査読無し][通常論文]
  • T Ichikawa, T Takahashi, H Koizumi, T Takada
    JOURNAL OF PHYSICAL CHEMISTRY A 104 12 2581 - 2586 2000年03月 [査読無し][通常論文]
     
    Hydrogen-atom tunneling from and to linear alkenes in organic matrices at 77 K has been studied for elucidating the effect of matrices on the rate of the tunneling. The rate of hydrogen-atom addition to the vinyl carbon of alkenes does not depend on the length of allyl chains bonded to the vinyl carbon, whereas the rate of hydrogen; atom abstraction by methyl radicals from the allylic carbon decreases with increasing length of alkyl chains bonded to the allylic carbon. These effects are explained as due to the resistance of matrices to the change of the C-C-C bond angle of the reacting carbon during the tunneling. For hydrogen-atom abstraction, the resistance causes the increase of the height of the potential barrier between the entrance and the exit of the tunneling channel, whereas the resistance does not cause the retardation of the tunneling to the vinyl carbon since the bond angle scarcely changes during the tunneling.
  • T Ichikawa, K Akiyama, G Satoh, H Koizumi
    CHEMICAL PHYSICS LETTERS 313 1-2 129 - 133 1999年11月 [査読無し][通常論文]
     
    The emission of alkaline ions from zeolite 4A has been studied for elucidating the mechanism of thermionic emission from solid electrolytes. The zeolite heated on an inert ceramic holder with infrared light does not emit neutral and charged species except for alkaline metal ions R+, which indicates that the thermionic emission is a nonstoichiometric chemical reaction, as RAlO2SiO2 --> delta R++delta e(-)+R1-deltaAlO2SiO2. The parallelism between the intensity of the thermionic emission and the ionic conductivity of the zeolite suggests that the ionic conduction of alkaline ions is necessary for reducing the energy of the thermionic emission. (C) 1999 Elsevier Science B.V. All rights reserved.
  • T Ichikawa, K Kagei, Y Ishitani, H Tachikawa, H Koizumi
    RADIATION PHYSICS AND CHEMISTRY 55 5-6 529 - 534 1999年08月 [査読無し][通常論文]
     
    Hydrogen-atom transfer from organic molecules to free deuterium atoms and to methyl radicals in cryogenic organic solids due to quantum-mechanical tunneling of C-H hydrogen was studied for elucidating the control factors for the reaction. The following differences were found in comparison with regular thermal reactions: (1) The rate of hydrogen-atom tunneling decreases with increasing number and length of alkyl chains attaching to C-H carbon to be hydrogen-abstracted. This is due to the increase of steric hindrance to the deformation of the chemical bonds of the C-H carbon. The abstraction accompanies the change of the chemical bonds for the C-H carbon from sp(3) to sp(2), SO that prevention of the deformation by the alkyl chains causes the increase of the thickness of the potential barrier for the tunneling. The tunneling rate therefore decreases. (2) The rate of abstraction increases with the energy released by the reaction. The energy is used to excite the vibrational states of product molecules, which accelerates the tunneling from the initial reactant state to the final product state. (C) 1999 Elsevier Science Ltd. All rights reserved.
  • H Yoshida, H Koizumi, T Ichikawa, J Kubo
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 151 1-4 367 - 371 1999年05月 [査読無し][通常論文]
     
    Radiation-chemical reactions of 9,10-dihydrophenanthrene in cyclohexane solution and tetralin in 3-methylpentane matrix were studied by means of the pulse radiolysis at room temperature and by gamma-irradiation at 77 K, respectively, in order to elucidate chemically the inhibition of radiation-induced deterioration of polyolefins due to added hydroaromatic compounds. Observed optical absorption spectra showed that salute compounds efficiently scavenge positive hole and electron to form cation- and anion-radical. Two kinds of neutral radicals (by elimination of H-atom from, and by addition of H-atom to hydroaromatic solutes) were generated secondarily from the ion radicals. No evidence could be obtained for direct scavenging of H atom or solvent radicals by added solutes. The inhibition of radiation-induced deterioration of polyolefins is likely due to positive- and negative-charge scavenging rather than free-radical scavenging. (C) 1999 Elsevier Science B.V. All rights reserved.
  • KOIZUMI Hitoshi
    放射線化学 67 40 - 44 1999年03月31日 [査読無し][通常論文]
  • J. Phys. Chem. B 103 19 3812 - 3817 1999年 [査読無し][通常論文]
  • Chem. Phys. Letters 300 1/2 253 - 256 1999年 [査読無し][通常論文]
  • Photoinduced Isomerization of Alkyl Radicals Trapped in Low Temperature Solids
    Hoshasen Kagaku(Readiation Chemistry) 67 40 - 44 1999年 [査読無し][通常論文]
  • Chemical Physics Letters 300 1-2 253 - 256 1999年 [査読無し][通常論文]
  • T Ichikawa, H Koizumi, J Kumagai
    JOURNAL OF PHYSICAL CHEMISTRY B 101 50 10698 - 10703 1997年12月 [査読無し][通常論文]
     
    The orbital structures of conduction electrons on permethylated oligosilane, Si-8(CH3)(18), and poly(cyclohexylmethylsilane) have been determined by analyzing the electron spin-echo envelope modulation signals of the radical anions of these silanes in a deuterated rigid matrix at 77 K. The conduction electron on permethylated oligosilane is delocalized over the entire main chain, whereas that on poly(cyclohexylmethylsilane) is localized on a part of the main chain composed of about six Si atoms, Quantum-chemical calculations suggest that Anderson localization due to fluctuation of sigma conjugation by conformational disorder of the main chain is responsible for the localization of both the conduction electron and the hole.
  • T Takada, H Koizumi, K Kagei, T Ichikawa, H Yoshida
    JOURNAL OF PHYSICAL CHEMISTRY B 101 22 4379 - 4382 1997年05月 [査読無し][通常論文]
     
    Photoinduced isomerization of protiated and deuterated hexyl radicals in 77 K solid n-hexanes was examined. 2- and 3-hexyl-h(13) radicals in n-hexane-h(14) isomerize to 1-hexyl-h(13) radicals with the irradiation of 254 nm light. This isomerization is suppressed by replacing the six hydrogen atoms of the methyl groups with deuterium atoms. The quantum yield for the isomerization of 2- and 3-hexyl-1,1,1,6,6,6-d(6) in n-hexane-1,1,1,6,6,6-d(6) and of 2- and 3-hexyl-d(13) in n-hexane-d(14) is less than 1/16 of that of 2- and 3-hexyl-h(13) radicals in n-hexane-h(13) Photoinduced isomerization of hexyl-h(13) radicals in 77 K n-hexane-d(14) was also examined. 2- and 3-hexyl-h(13) radicals isomerize to 1-hexyl-h(13) radical even in the solid. The isomerization may hence occur through an intramolecular reaction. The large isotope effect may arise in the course of either the isomerization in the excited state or the relaxation process of the excited primary radical.
  • T Ichikawa, K Kagei, J Kumagai, H Koizumi, H Yoshida, JI Kubo
    RADIATION PHYSICS AND CHEMISTRY 49 4 433 - 436 1997年04月 [査読無し][通常論文]
     
    Formation of the 2,3,4-trihydronaphtyl radical from the radical cation of tetralin by charge recombination has been studied by electronic absorption spectroscopy. Illumination of the gamma-irradiated glassy alkane solution of tetralin with visible light at 77 K causes electron ejection from the radical anion of tetralin, and the ejected electron recombines with the radical cation to generate the excited tetralin, which then converts to the neutral 2,3,4-trihydronaphtyl radical. The quantum yield of the formation of the neutral radical is approximately the same as that for UV-excited tetralin, which suggests that highly excited states of tetralin are not important for the formation of the neutral radical. The highly excited tetralin molecules generated by charge recombination relax to the first excited state without any chemical reaction, and the scission of a C-H bond takes place under the first excited state. (C) 1997 Elsevier Science Ltd.
  • Nucl. Instr. and Meth. 132 4 633 - 638 1997年 [査読無し][通常論文]
  • Radiat. Phys. Chem. 50 6 567  1997年 [査読無し][通常論文]
  • H Koizumi, T Ichikawa, H Hoshida
    APPLIED RADIATION AND ISOTOPES 47 11-12 1205 - 1209 1996年11月 [査読無し][通常論文]
     
    In order to extend the application of alanine dosimetry, the behavior of free radicals in solid alpha-alanine irradiated with gamma-rays and with ion beams was studied by electron spin resonance. Stable neutral radicals are produced through the decomposition of originally generated ion radicals in alanine irradiated at 300 K, while at 77 K the ion radicals are stable, and also do not decompose. The rate of the combination reaction of the neutral radicals and of the ion radicals was studied by measuring the-saturation behavior of the radical concentration in gamma-radiolysis at 300 and at 77 K. The yield of the neutral radicals was compared between 0.5, 1, 2 and 3 MeV H+, 0.5, 1, and 3 MeV He+, 175 MeV Ar3+ and 460 MeV Ar13+ ion irradiations. Dependence of the radical yield on the radiation quality is understood more in terms of the rate of the combination reaction between the ion radicals than with that between the neutral radicals, and has to do with high local dose within the ion tracks. Copyright (C) 1996 Elsevier Science Ltd
  • H Koizumi, T Ichikawa, H Yoshida, H Shibata, S Tagawa, Y Yoshida
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 117 3 269 - 274 1996年09月 [査読無し][通常論文]
     
    Radical formation in solid alpha-alanine irradiated with 0.5-, 1-, 2-, and 3-MeV H+, 0.5-, 1-, and 3-MeV He+ ions were studied by means of electron spin resonance. The radical yield (number of radicals per incident ion) is constant below the critical fluence of about 10(12) ions cm(-2). Above the critical fluence, the yield decreases with increasing ion fluence, G-value of the radical formation was obtained from the constant yield at the low fluences, Assuming a simple cylindrical shape of the ion tracks, the average radii of the ion tracks were estimated from the G-values, The estimated value of the radius is from 2 nm to 5 nm, The dependence of the radical yield on the ion fluence was simulated with the cylindrical model of ion tracks and dose-yield relationship for gamma-irradiation. The observed yield decreases more than the simulated one above the critical fluence. This difference is ascribed to higher damage on the solid alanine by the ion irradiation than by gamma-irradiation.
  • H Koizumi, S Kosugi, H Yoshida
    JOURNAL OF PHYSICAL CHEMISTRY 100 12 4848 - 4852 1996年03月 [査読無し][通常論文]
     
    Photoinduced isomerization of alkyl radicals of n-alkanes trapped in 77 K solids was examined by the ESR method. In crystalline n-alkanes, penultimate radicals (CH3C over dot HCH2-) and interior radicals (-CH2C over dot HCH2-) are converted to primary radicals (C over dot H2CH2-) with irradiation of 254 nm light. This isomerization occurs regardless of the crystal structure. There are isosbestic points in the integrated ESR spectra with different times of the UV irradiation: the ratio of the penultimate to the interior radicals remains constant during the isomerization. This indicates that the interior radicals are directly converted to the primary radicals. The isomerization does not proceed by successive reaction of hydrogen migrations, which mechanism may cause the formation of the penultimate radicals. Photoinduced isomerization from the penultimate radicals to the primary radicals was observed for alkyl radicals in methanol-d(4) glass. The photoinduced isomerization may hence proceed by intramolecular reactions and does not require intermolecular abstraction of a hydrogen atom from an adjacent alkane molecule.
  • Nuclear Instruments and Methods in Physics Research B 117 3 431 - 435 1996年 [査読無し][通常論文]
  • I EEE Trans. Dielectrics Electr. Insul. 3,233-236 1996年 [査読無し][通常論文]
  • Chem. Phys. Letters 242 3 320 - 324 1995年 [査読無し][通常論文]
  • VV KRUSHEV, H KOIZUMI, T ICHIKAWA, H YOSHIDA, H SHIBATA, S TAGAWA, Y YOSHIDA
    RADIATION PHYSICS AND CHEMISTRY 44 5 521 - 526 1994年11月 [査読無し][通常論文]
     
    The yield and local concentration of free radicals generated from alanine (alpha-aminopropionic acid) by irradiation with 3 MeV H+ and He+ ions were examined by means of electron spin resonance (ESR) and ESR power saturation methods at room temperature. The G-value of the radical formation showed a marked dependence on linear energy transfer (LET) of the ions. The G-value for the H+ ion (average LET: 28 eV/nm) was almost the same as that for gamma-irradiation and it was smaller by a factor of 1/4.7 for the He+ ion (average LET: 225 eV/nm). Combining the local concentration of the free radicals along the ion tracks with the G-values and the reported ion range, the radius of a track filled with free radicals was estimated to be 4 approximately 5 nm by assuming a simple rod-shaped track with a constant radius and homogeneous distribution of the free radicals in it. The track radius scarcely depends on the LET within the range examined. The radiation energy deposited in the core region of the ion track was concluded to spread over the rod to generate free radicals.
  • H KOIZUMI, S KOSUGI, H YOSHIDA
    JOURNAL OF PHYSICAL CHEMISTRY 98 43 11089 - 11093 1994年10月 [査読無し][通常論文]
     
    Photoinduced isomerization of alkyl radicals trapped in gamma-irradiated 77 K solid alkanes has been studied using electron spin resonance method. Alkyl radicals trapped in the crystalline solids of n-alkanes from n-C8H18 to n-C13H28 and in the glassy solids of 2- and 3-methylheptanes have been measured. Interior radicals (-CH2CHCH2-) trapped in the orthorhombic crystals of n-alkanes are converted to primary radicals (CH2CH2-) with irradiation of 254 nm light, whereas the interior alkyl radicals in the triclinic crystals of n-alkanes are converted to penultimate alkyl radicals (CH3CHCH2-) This selectivity of photoconversion is explained by the initial formation of the primary radicals in both the crystals and thermal radical conversion to the penultimate alkyl radicals in the triclinic crystals. Selective photoisomerization to primary radicals (CH2C7H15) has also been observed for penultimate radicals (CH3CHC6H13) trapped in gamma-irradiated 2- and 3-methylheptanes. Excited alkyl radicals trapped in solid alkanes hence initially isomerize to primary radicals regardless of the structure of the solids.
  • H KOIZUMI, K LACMANN, WF SCHMIDT
    JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA 67 3 417 - 427 1994年06月 [査読無し][通常論文]
     
    Electron emission from low vapor pressure liquids induced by vacuum ultravoilet light was measured as a function of photon energy between 6 eV and 10.8 eV. Absolute quantum yields were determined for 17 organic compounds comprising hydrocarbons, phthalates, phosphates, dicarboxylic esters, amines and polysiloxane fluids. The quantum yields rise from 10(-6) to 10(-1) with increasing photon energy. Systematic changes of the yields with the molecular structure of the liquids were observed. The photoemission threshold energies of 11 liquids have been determined in this work. The electron energy levels and the photoemission process are discussed by taking into account the electronic properties of the isolated molecules, the influence of charge polarization, and the transport of hot electrons through the liquid/vapor interface.
  • Chem. Phys. Letters 21 137 - 142 1994年 [査読無し][通常論文]
  • Nucl. Instrum. Methods A 327,75-77 1993年 [査読無し][通常論文]
  • H KOIZUMI, K LACMANN, WF SCHMIDT
    JOURNAL OF PHYSICS D-APPLIED PHYSICS 25 5 857 - 861 1992年05月 [査読無し][通常論文]
     
    Light-induced electron emission from silicone fluids has been measured as a function of photon energy. Emission energy thresholds were determined. Taking into account published data on the photoconductivity energy threshold in these fluids, values for the polarization energy of the positive ion and for the energy of the electronic conduction level could be deduced. In addition, some gas phase ionization potentials were determined.
  • Effect of Solid Phase on the Selectivity of Alkyl Radical Formation By Gamma-Irradiation of Branched Alkanes
    Radiat. Phys. Chem. 40 2 1992年 [査読無し][通常論文]
  • J. Chem. Phys. 95 8 5846 - 5852 1991年 [査読無し][通常論文]
  • VUV-Optical Oscillator Strength Distributions of Molecules and Their Implications to Early Events in Radiation Chemistry
    Radiat. Phys. Chem. 32 1 87 - 92 1989年 [査読無し][通常論文]
  • Ionization Efficiencies of C3H6, C4H8, C6H12, C2H60, and C3H8O Isomers
    Radiat. Phys. Chem. 32 1 111 - 115 1988年 [査読無し][通常論文]
  • H KOIZUMI, K HIRONAKA, K SHINSAKA, S ARAI, H NAKAZAWA, A KIMURA, Y HATANO, Y ITO, YW ZHANG, A YAGISHITA, K ITO, K TANAKA
    JOURNAL OF CHEMICAL PHYSICS 85 8 4276 - 4279 1986年10月 [査読無し][通常論文]
  • H KOIZUMI, M UKAI, Y TANAKA, K SHINSAKA, Y HATANO
    JOURNAL OF CHEMICAL PHYSICS 85 4 1931 - 1937 1986年08月 [査読無し][通常論文]
  • Chem. Phys. Letters 119(4), 327-330 1985年 [査読無し][通常論文]
  • H KOIZUMI, T YOSHIMI, K SHINSAKA, M UKAI, M MORITA, Y HATANO, A YAGISHITA, K ITO
    JOURNAL OF CHEMICAL PHYSICS 82 11 4856 - 4861 1985年 [査読無し][通常論文]

書籍

  • 有機電子デバイスのための導電性高分子の物性と評価
    (担当:分担執筆範囲:第6章導電性高分子の可溶化技術とドープ状態の安定性)
    シーエムシー出版 2012年06月
  • 有機デバイス・材料の耐久性向上および長寿命化技術
    (担当:分担執筆範囲:第2章第3項P3HTおよびMDMO-PPVの光および熱劣化とその機構)
    情報機構 2011年12月
  • 放射線化学のすすめ
    (担当:分担執筆範囲:イオンビームと線質効果、イオンビームとナノ構造体、有機低分子のイオンビーム放射線化学)
    学会出版センター 2006年02月
  • 新しい物理化学実験
    (担当:分担執筆範囲:第11章分光光度計の原理と構造)
    三共出版 1996年
  • Light-induced electron emission from surfaces of organic liquids
    Linking the gaseous and condensed phases of matters : the behavior of slow electrons0 1994年

作品等

  • 高分子のイオンビーム架橋によるミクロ構造体の作製
    1997年 -2001年
  • 照射有機固体中におけるラジカル生成の局所分布と線質効果
    1993年 -1996年

その他活動・業績

  • 小泉均 放射光 7 (4) 328 -344 1994年11月 [査読無し][通常論文]
  • Photoionization quantum yields in condensed phase
    J.Jpn.Soc.Synchrotron Radiat. Res. 7 (4) 328 -344 1994年 [査読無し][通常論文]

特許

  • ポリマー圧電物質とその製造方法
    特願2004-225415
  • 解離性電子付着基を有する高分子化合物の製造方法及びその主鎖切断方法
    特開2004-026981
  • 高分子化合物の主鎖切断方法
    特開2000-284481
  • 圧電・焦電体及びその製造方法
    特開2002-105226
  • 電離放射線の測定方法及び線量計
    特開2002-107454
  • Manufacture of polymers having dissociative electron attachment groups and scission of the polymer main chains.
    JP 2004026981
  • Method for scission of polymer main chain for x-ray lithography
    JP200284481
  • Organic polymer-based piezoelectric/pyroelectric body and their manufacture
    JP 2002105226
  • Dosimeter based on measurement of ionizing radiation
    JP 2002107454

共同研究・競争的資金等の研究課題

  • 化学増幅反応を利用した高感度線量計の開発
  • 高エネルギービームを用いた機能性高分子材料の作製
  • 化学増幅反応を利用した高感度線量計の開発
  • イオン照射による有機固体中での化学反応
  • High-sensitivity radiation dosimeter utilizing chemical amplification reactions
  • Functionalization of Polymers by High Energy Beams
  • High-sensitivity radiation dosimeter utilizing chemical amplification reactions
  • Chemical reactions in ion-irradiated organic solids

教育活動情報

主要な担当授業

  • 応用物質化学(有機物性化学)
    開講年度 : 2018年
    課程区分 : 修士課程
    開講学部 : 総合化学院
    キーワード : 高分子,ガラス転移,ゴム弾性,粘弾性,クリープ,応力緩和,温度-時間換算則、高分子の耐候性
  • 量子化学Ⅰ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 量子力学 シュレーディンガー方程式,原子,分子,エネルギー遷移,分光学
  • 応用化学学生実験Ⅰ
    開講年度 : 2018年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 実験技術、安全、酸化還元滴定、キレート滴定、酸塩基平衡、錯形成平衡、吸光光度法、クラジウス-クラペイロンの式、蒸発エンタルピー、電荷移動錯体、分子間相互作用、電極現象、PC計測制御、吸収・蛍光スペクトル、分子軌道論、反応速度、アレニウスの式


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