2024/06/25 更新

写真a

ミウラ トモアキ
三浦 智明
MIURA Tomoaki
所属
教育研究院 自然科学系 数理物質科学系列 准教授
自然科学研究科 数理物質科学専攻 准教授
理学部 理学科 准教授
職名
准教授
外部リンク

学位

  • 博士(理学) ( 2008年3月   静岡大学 )

  • 修士(理学) ( 2005年3月   筑波大学 )

  • 学士(理学) ( 2003年3月   筑波大学 )

研究分野

  • ナノテク・材料 / 機能物性化学

経歴

  • 新潟大学   自然科学研究科 数理物質科学専攻   准教授

    2024年6月 - 現在

  • 新潟大学   理学部 理学科   准教授

    2024年6月 - 現在

  • 新潟大学   教育研究院 自然科学系 数理物質科学系列   准教授

    2024年6月 - 現在

  • 新潟大学   理学部 理学科   助教

    2017年4月 - 2024年5月

  • 新潟大学   自然科学研究科 数理物質科学専攻   助教

    2013年1月 - 現在

  • 新潟大学   自然科学研究科 数理物質科学専攻   助教

    2013年1月 - 現在

  • 新潟大学   無機物質化学   助教

    2013年1月 - 2017年3月

▶ 全件表示

 

論文

  • Realtime Observation of Carrier Trapping and Recombination in a Bulk Heterojunction Film by Simultaneous Optical and Electrical Detection 査読

    Tomoaki Miura, Ryoya Akiyama, So Kobayashi, Tadaaki Ikoma

    The Journal of Physical Chemistry C   125 ( 41 )   22668 - 22673   2021年10月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    Since the photocharge generation efficiency has reached nearly 100% for recent organic photovoltaic film materials, clarification of loss mechanisms becomes of increasing importance. Here, we report a new time-resolved measurement method that enables simultaneous detection of the optical absorption and electric current due to photogenerated carriers in organic semiconductor films. Microsecond-order decays of both the number density (recombination) and the averaged drift mobility (trapping) of photocarriers are quantitatively observed for an identical device of a regioregular poly[3-hexylthiophene-2,5-diyl]:(6,6)-phenyl C-61 butyric acid methyl ester bulk heterojunction film. The decay feature of the time-dependent mobility is highly dispersive especially at lower temperatures. It can be explained by fast thermalization of "hot" photocarriers into lower energy sites, which is followed by thermally activated hopping. This quantitative time-resolved observation method can be a powerful tool for characterization and optimization of photovoltaic materials.

    DOI: 10.1021/acs.jpcc.1c06879

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  • Gigantic Magnetic Field Effect on the Long-Lived Intermolecular Charge-Separated State Created at the Nonionic Bilayer Membrane 査読

    Tomoaki Miura, Kiminori Maeda, Yoshimi Oka, Tadaaki Ikoma

    The Journal of Physical Chemistry B   122 ( 50 )   12173 - 12183   2018年12月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society ({ACS})  

    DOI: 10.1021/acs.jpcb.8b08389

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  • Magnetic Control of the:Charge-Separated State Lifetime Realized by Covalent Attachment of a Platinum Complex 査読

    Tomoaki Miura, Dai Fujiwara, Kimio Akiyama, Takafumi Horikoshi, Shuichi Suzuki, Masatoshi Kozaki, Keiji Okada, Tadaaki Ikoma

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   8 ( 3 )   661 - 665   2017年2月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Dynamics of the photogeneratedcharge-separated (CS) state is studied for. a newly synthesized molecular triad, in which the donor (D) dimethoiytriphenylamine; 1,3-bis(2-pyridylimino)isoindolate platinum (BPIPt), and the acceptor (A). naphthaldiimide are linked with a triethynylbenzene unit (BPIPt-DA). Photoexcitation of BPIPt gives rise to generation, of a long lived (similar to 4 mu s) CS Tstate BPIPt-D(+)A(-), Of which the lifetime is con, Siderably increased by applied magnetic field of 270 mT.: The positive magnetic field,effect (MFE) is in contrast to the negative MFE for the reference DA molecule, which indicates successful switching of the initial spin, state of the CS state from singlet to triplet Simulations of the MFE and time resolved electron paramagnetic resonance show that spin-selective charge recombination and spin relaxation Are. Unaffected by attachment of BPIPt. The minimum impact of heavy atom substitution on the. electronic and magnetic properties-hae-been.. realized by the small electronic coupling mediated by the rigid meta-triethynylbenzene.

    DOI: 10.1021/acs.jpclett.6b02887

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  • Single-Molecule Magnetoluminescence from a Spatially Confined Persistent Diradical Emitter 査読

    Ryota Matsuoka, Shojiro Kimura, Tomoaki Miura, Tadaaki Ikoma, Tetsuro Kusamoto

    Journal of the American Chemical Society   145 ( 25 )   13615 - 13622   2023年6月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/jacs.3c01076

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  • Origin of the Delayed Fluorescence by Triplet–Triplet Annihilation in Solids with a Power Law Exponent of between −1/2 and −1 査読

    Kazuhiko Seki, Tomoaki Miura, Tadaaki Ikoma

    The Journal of Physical Chemistry C   127 ( 20 )   9562 - 9572   2023年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acs.jpcc.3c02128

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  • Triarylamine-Substituted Benzimidazoliums as Electron Donor–Acceptor Dyad-Type Photocatalysts for Reductive Organic Transformations 査読

    Ryo Miyajima, Yuuki Ooe, Tomoaki Miura, Tadaaki Ikoma, Hajime Iwamoto, Shin-ya Takizawa, Eietsu Hasegawa

    Journal of the American Chemical Society   145 ( 18 )   10236 - 10248   2023年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/jacs.3c01264

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  • Transient photocurrent and optical absorption of disordered thin-film semiconductors: In-depth injection and nonlinear response 査読

    Kazuhiko Seki, Naoya Muramatsu, Tomoaki Miura, Tadaaki Ikoma

    The Journal of Chemical Physics   158 ( 11 )   114704 - 114704   2023年3月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:AIP Publishing  

    The time-of-flight method is a fundamental approach for characterizing the transport properties of semiconductors. Recently, the transient photocurrent and optical absorption kinetics have been simultaneously measured for thin films; pulsed-light excitation of thin films should give rise to non-negligible in-depth carrier injection. Yet, the effects of in-depth carrier injection on the transient currents and optical absorption have not yet been elucidated theoretically. Here, by considering the in-depth carrier injection in simulations, we found a 1/ t<sup>1− α/2</sup> initial time ( t) dependence rather than the conventional 1/ t<sup>1− α</sup> dependence under a weak external electric field, where α &lt; 1 is the index of dispersive diffusion. The asymptotic transient currents are not influenced by the initial in-depth carrier injection and follow the conventional 1/ t<sup>1+ α</sup> time dependence. We also present the relation between the field-dependent mobility coefficient and the diffusion coefficient when the transport is dispersive. The field dependence of the transport coefficients influences the transit time in the photocurrent kinetics dividing two power-law decay regimes. The classical Scher–Montroll theory predicts that a<sub>1</sub> + a<sub>2</sub> = 2 when the initial photocurrent decay is given by [Formula: see text] and the asymptotic photocurrent decay is given by [Formula: see text]. The results shed light on the interpretation of the power-law exponent of [Formula: see text] when a<sub>1</sub> + a<sub>2</sub> ≠ 2.

    DOI: 10.1063/5.0143683

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  • Temperature-induced structural transition in an organic-inorganic hybrid layered perovskite (MA)(2)PbI2-xBrx(SCN)(2) 査読

    Takuya Ohmi, Tomoaki Miura, Kei Shigematsu, Alexandra A. Koegel, Brian S. Newell, James R. Neilson, Tadaaki Ikoma, Masaki Azuma, Takafumi Yamamoto

    CRYSTENGCOMM   24 ( 30 )   5428 - 5434   2022年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ROYAL SOC CHEMISTRY  

    Layered hybrid organic-inorganic halide perovskites have emerged as durable and tunable candidates for optoelectronic materials due to their outstanding properties. Here, we report the temperature-induced structural transition and photophysical properties of the layered perovskite (MA)(2)PbI2-xBrx(SCN)(2) (MA = CH3NH3; 0 <= x <= 1.2). Synchrotron X-ray diffraction measurements demonstrate that there is a first-order structural phase transition with an increase of the interlayer distance in (MA)(2)PbI2(SCN)(2) (x = 0) at 315 K. We attribute this transition to order-disorder transformations of the molecular ions, MA(+) and SCN-. The observed transition temperature decreases with Br substitution (from 320 K to 270 K), suggesting a weakening of bonding interaction between the molecular ions. A decrease in the decomposition temperature was also observed by Br substitution, indicating that the strength of interlayer bonding is coupled with the thermal stability of the layered perovskite. Photocurrent transient measurements for (MA)(2)PbI2(SCN)(2) reveal a dramatic decrease of the fast decay component upon heating, indicating that the structural transition decreases the carriers in the crystalline domain by random distortion of the perovskite layer derived from disordering of molecular ions. This study provides insight into the structure and photophysical properties of the thiocyanate layered perovskite family.

    DOI: 10.1039/d2ce00733a

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  • Copper(II) Complexes of 10,20-Diaryl-5,15-diazaporphyrin: Alternative Synthesis, Excited State Dynamics, and Substituent Effect on the <sup>1</sup>O<inf>2</inf>-Generation Efficiency 査読

    Hikari Ochiai, Tomoaki Miura, Tadaaki Ikoma, Mao Minoura, Haruyuki Nakano, Yoshihiro Matano

    Bulletin of the Chemical Society of Japan   95 ( 3 )   427 - 432   2022年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:CHEMICAL SOC JAPAN  

    The synthesis, excited state dynamics, and substituent effect on the 1O2-generation efficiency of several copper(II) complexes of 5,15-diazaporphyrin (CuDAPs) bearing peripheral substituents are reported. 10,20-Diaryl-CuDAPs were prepared via a new method consisting of metal-templated cyclization and N-dealkylation as key steps. The effect of the β-substituents on the optical and redox properties of CuDAP was stronger than that of the meso-aryl groups, which can be explained by considering the characteristics of the HOMO and LUMO of the DAP ring. The excited state dynamics and 1O2-generation efficiency of CuDAPs were studied using time-resolved spectroscopic techniques; the electronic effect of the meso-aryl groups on the triplet lifetime and 1O2-generation quantum yield was relatively weak, whereas that of the β-(1-pyrazolyl) groups was appreciable. The analysis of the temperature dependence of phosphorescence spectra of 10,20-bis(2,4,6-trimethylphenyl)-CuDAP allowed the energy gap between the excited trip-quartet and trip-doublet states to be determined. The relatively long triplet lifetimes of CuDAPs show their potential for future application as photosensitizers.

    DOI: 10.1246/bcsj.20220002

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  • An Element‐Substituted Cyclobutadiene Exhibiting High‐Energy Blue Phosphorescence 査読

    Yoshiaki Shoji, Yasuhiro Ikabata, Ivan Ryzhii, Rabia Ayub, Ouissam El Bakouri, Taiga Sato, Qi Wang, Tomoaki Miura, Buddhika S. B. Karunathilaka, Youichi Tsuchiya, Chihaya Adachi, Henrik Ottosson, Hiromi Nakai, Tadaaki Ikoma, Takanori Fukushima

    Angewandte Chemie International Edition   60 ( 40 )   21817 - 21823   2021年7月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

    DOI: 10.1002/anie.202106490

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.202106490

  • Photogenerated Radical Pair between Flavin and a Tryptophan-Containing Transmembrane-Type Peptide in a Large Unilamellar Vesicle 査読

    Yoshimi Oka, Tomoaki Miura, Tadaaki Ikoma

    The Journal of Physical Chemistry B   125 ( 16 )   4057 - 4066   2021年4月

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    担当区分:責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    Electron-transfer (ET) reactions in biological systems, such as those with magnetic sensors based on flavoproteins and electron transport at biomembrane interfaces, are interesting and important issues that require understanding. As a model system of flavoproteins in biomimetic environments, we report the dynamics of the radical pair generated by photoinduced ET between riboflavin tetrabutylate (RFTB) and tryptophan (Trp) residues in a transmembrane-type polypeptide, both of which are distributed in a large unilamellar vesicle of 1,2-dimyristoyl-sn-glycero-3-phosphocholine. The Trp residues locate near the hydrophilic membrane interface, as confirmed by a dual-fluorescence quenching assay. The fluorescence and transient absorption upon photoexcitation of RFTB indicate that ET from both the singlet and triplet excited states occurs at the hydrophilic interface, whereas the RFTB in the hydrophobic region does not contribute to ET. The ET efficiency and the magnetic field effect (MFE) on the RFTB anion increase significantly above the gel-to-liquid crystal phase transition temperature due to a decrease in microviscosity. The MFE analysis indicates that the radical pair generated from the triplet ET channel exhibits a long lifetime as those in micellar systems due to the strong cage effect of the vesicle.

    DOI: 10.1021/acs.jpcb.1c01231

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  • スピン動力学に基づく光生成電荷分離状態の反応制御

    三浦 智明

    光化学   51 ( 1 )   28 - 31   2020年4月

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    担当区分:筆頭著者  

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  • Spin-dependent electron transfer dynamics in a platinum-complex–donor–acceptor triad studied by transient-absorption detected magnetic field effect 査読

    Tomoaki Miura, Kio Miyaji, Takafumi Horikoshi, Shuichi Suzuki, Masatoshi Kozaki, Keiji Okada, Tadaaki Ikoma

    The Journal of Chemical Physics   151 ( 23 )   234306 - 234306   2019年12月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1063/1.5127940

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  • An impact of higher fullerene on charge recombination in organic solar cell studied by magnetoconductance 査読

    Ryota Shoji, Tomoaki Miura, Tadaaki Ikoma

    Organic Electronics   75   105383 - 105383   2019年12月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:Elsevier BV  

    DOI: 10.1016/j.orgel.2019.105383

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  • Studies on coherent and incoherent spin dynamics that control the magnetic field effect on photogenerated radical pairs 招待 査読

    Tomoaki Miura

    MOLECULAR PHYSICS   118 ( 6 )   e1643510   2019年7月

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    担当区分:筆頭著者, 最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1080/00268976.2019.1643510

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  • Effects of the Peripheral Substituents, Central Metal, and Solvent on the Photochemical and Photophysical Properties of 5,15-Diazaporphyrins 査読

    ChemPlusChem   84 ( 6 )   740 - 745   2019年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1002/cplu.201900087

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    その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/cplu.201900087

  • Visible Light and Hydroxynaphthylbenzimidazoline Promoted Transition-Metal-Catalyst-Free Desulfonylation of N-Sulfonylamides and N-Sulfonylamines 査読 国際誌

    Eietsu Hasegawa, Yuto Nagakura, Norihiro Izumiya, Keisuke Matsumoto, Tsukasa Tanaka, Tomoaki Miura, Tadaaki Ikoma, Tadaaki Ikoma, Hajime Iwamoto, Kan Wakamatsu

    Journal of Organic Chemistry   83 ( 18 )   10813 - 10825   2018年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    Copyright © 2018 American Chemical Society. A visible light promoted process for desulfonylation of N-sulfonylamides and -amines has been developed, in which 1,3-dimethyl-2-hydroxynaphthylbenzimidazoline (HONap-BIH) serves as a light absorbing, electron and hydrogen atom donor, and a household white light-emitting diode serves as a light source. The process transforms various N-sulfonylamide and -amine substrates to desulfonylated products in moderate to excellent yields. The observation that the fluorescence of 1-methyl-2-naphthoxy anion is efficiently quenched by the substrates suggests that the mechanism for the photoinduced desulfonylation reaction begins with photoexcitation of the naphthoxide chromophore in HONap-BIH, which generates an excited species via intramolecular proton transfer between the HONap and BIH moieties. This process triggers single electron transfer to the substrate, which promotes loss of the sulfonyl group to form the free amide or amine. The results of studies employing radical probe substrates as well as DFT calculations suggest that selective nitrogen-sulfur bond cleavage of the substrate radical anion generates either a pair of an amide or amine anio

    DOI: 10.1021/acs.joc.8b01536

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  • Magnetoconductance Study on Nongeminate Recombination in Solar Cell Using Poly(3-hexylthiophene) and [6,6]-Phenyl-C-61-butyric Acid Methyl Ester 査読

    Shoji Ryota, Omori Takuya, Wakikawa Yusuke, Miura Tomoaki, Ikoma Tadaaki

    ACS OMEGA   3 ( 8 )   9369 - 9377   2018年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/acsomega.8b01746

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  • 有機薄膜太陽電池の物理化学

    三浦 智明

    化学と教育   66 ( 7 )   338 - 339   2018年7月

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    担当区分:筆頭著者  

    DOI: 10.20665/kakyoshi.66.7_338

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  • Benzimidazolium Naphthoxide Betaine Is a Visible Light Promoted Organic Photoredox Catalyst 査読

    Eietsu Hasegawa, Norihiro Izumiya, Tomoaki Miura, Tadaaki Ikoma, Hajime Iwamoto, Shin-Ya Takizawa, Shigeru Murata

    Journal of Organic Chemistry   83 ( 7 )   3921 - 3927   2018年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society  

    Benzimidazolium naphthoxide (-ONap-BI+) was first synthesized and utilized as an unprecedented betaine photoredox catalyst. Photoexcited state of -ONap-BI+ generated by visible light irradiation catalyzes the reductive deiodination as well as desulfonylation reactions in which 1,3-dimethyl-2-phenylbenzimidazoline (Ph-BIH) cooperates with as an electron and hydrogen atom donor. Significant solvent effects on the reaction progress were discovered, and specific solvation toward imidazolium and naphthoxide moieties of -ONap-BI+ was proposed.

    DOI: 10.1021/acs.joc.8b00282

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  • Solvent Viscosity Effect on Triplet-Triplet Pair in Triplet Fusion 査読

    Kana Yokoyama, Yusuke Wakikawa, Tomoaki Miura, Jun-ichi Fujimori, Fuyuki Ito, Tadaaki Ikoma

    JOURNAL OF PHYSICAL CHEMISTRY B   119 ( 52 )   15901 - 15908   2015年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The effect of the solvent viscosity dependence of time-resolved magnetoluminescence (ML) on the delayed fluorescence of 9,10-diphenylanthracene (DPA) sensitized by platinum octaethylporphyrin has clarified the structure and dynamics of the triplet triplet pair (TT), i.e., the transition state of triplet fusion. Phase inversion of the ML effect with time provides evidence for the recycle dynamics of the excited triplet state for DPA in triplet fusion. The electron spin-relaxation by random molecular rotation causes intersystem crossing among the different spin states of the triplet-triplet pair and allows the (TT)-T-3,5 to engage in triplet fusion. Therefore, slow-down of the molecular diffusion by an increase in the solvent viscosity can enhance the triplet fusion yield. However, the reduction of the ML effect observed in quite high viscosity solvents suggests that the substantially slow rotational motion decreases the triplet fusion yield due to steric factors in electron exchange from the triplet-triplet pair.

    DOI: 10.1021/acs.jpcb.5b11208

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  • Aryl-substituted dimethylbenzimidazolines as effective reductants of photoinduced electron transfer reactions 査読

    Eietsu Hasegawa, Taku Ohta, Shiori Tsuji, Kazuma Mori, Ken Uchida, Tomoaki Miura, Tadaaki Ikoma, Eiji Tayama, Hajime Iwamoto, Shin-ya Takizawa, Shigeru Murata

    TETRAHEDRON   71 ( 34 )   5494 - 5505   2015年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    Photoinduced electron transfer (PET) reactions promoted by 2-aryl substituted 1,3-dimethylbenzimidazolines (Ar-DMBIH) were investigated. Excited states of Ar-DMBIH, formed by irradiation using light above 360 initiate PET reductions of various organic substrates, including transformations of epoxy ketones to aldols, free radical rearrangements such as the Dowd-Beckwith ring-expansion and 5-exo hexenyl cyclization, deprotection of N-sulfonyl-indols, and allylation of acyl formates. In these processes, Ar-DMBIH possessing 1-naphthyl, 2-naphthyl, 1-pyrenyl and 9-anthryl substituents formally act as two electron and one proton donors while the hydroxynaphthyl substituted derivative serves as a two electron and two proton donor. On the basis of the results of absorption spectroscopy studies, cyclic voltammetry and DFT calculation, a mechanistic sequence for these reduction reactions is proposed that involves initial photoexcitation of the aryl chromophore of the Ar-DMBIH followed by single electron transfer (SET) to the organic substrate to generate the radical cation of benzimidazoline and the radical anion of the substrate. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.tet.2015.06.071

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  • Effect of Molecular Diffusion on the Spin Dynamics of a Micellized Radical Pair in Low Magnetic Fields Studied by Monte Carlo Simulation 査読

    Tomoaki Miura, Hisao Murai

    JOURNAL OF PHYSICAL CHEMISTRY A   119 ( 22 )   5534 - 5544   2015年6月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Magnetic field effect is a powerful tool to study dynamics and kinetics of radical pairs (RPs), which are one of the most important intermediates for organic photon-energy conversion reactions. However, quantitative discussion regarding the relationship between the modulation of interelectron interactions and spin dynamics at low magnetic fields (&lt;10 mT) is still an open question. We have studied the spin dynamics of a long-lived RP in a micelle by newly developed Monte Carlo simulation, in which fluctuations of the exchange and magnetic dipolar interactions by in-cage diffusion are directly introduced to the time-domain spin dynamics calculation. State-dependent relaxation/dephasing times of a few to a few tens of nanoseconds are obtained by simulations without hyperfine interactions (HFIs) as a function of the mutual diffusion constant (similar to 10(-6) cm(2)/s). Simulations with the HFIs exhibit incoherent singlet-triplet (S-T) mixings resulting from interplay between the HFIs and the fluctuating spin-spin interactions. The experimentally observed incoherent S-T mixing of similar to 20 ns at 3 mT for a singlet-born RP in a sodium dodecyl sulfate micelle is reproduced by the simulation with reasonable diffusion coefficients. The computational method developed here contributes to quantitative detection of molecular motion that governs the recombination efficiency of RPs.

    DOI: 10.1021/acs.jpca.5b02183

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  • Long-Distance Sequential Charge Separation at Micellar Interface Mediated by Dynamic Charge Transporter: A Magnetic Field Effect Study 査読

    Tomoaki Miura, Kiminori Maeda, Hisao Murai, Tadaaki Ikoma

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   6 ( 2 )   267 - 271   2015年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Construction of photogenerated long-lived charge-separated states is crucial for light-energy conversion using organic molecules. For realization of cheap and easy-to-make long-distance electron transfer (ET) systems, we have developed a supramolecular donor(D)chromophore(C)acceptor(A) triad utilizing a micellar interface. Alkyl viologen (A(2+)) is adsorbed on the hydrophilic interface of Triton X-100 micelle, which bears D units in the hydrophobic core. Excited triplet state of a hydrophobic flavin C entrapped in the supercage gives rise to primary ET from D, which is followed by the secondary ET from C to A(2+) to give the long-lived (&gt;10 mu s) charge-separated state with negligible yield of escaped C. Analysis of magnetic field effect reveals that diffusion of C from the core to the hydrophilic interface leads to long-distance ET with a low charge recombination yield of similar to 20%. This novel concept of dynamic charge transporter has important implications for development of photon-energy conversion systems in solution phase.

    DOI: 10.1021/jz502495u

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  • Carrier Dynamics in PentacenelC(60) Bilayer Solar Cell Investigated through the Magnetoconductance 査読

    Takuya Omori, Yusuke Wakikawa, Tomoaki Miura, Yuji Yamaguchi, Ken-ichi Nakayama, Tadaaki Ikoma

    JOURNAL OF PHYSICAL CHEMISTRY C   118 ( 49 )   28418 - 28424   2014年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We demonstrate the magnetoconductance (MC) effect originated from depressing the spin mixing in encounter pairs under the external magnetic field provides quantitative information about the singlet fission, the charge recombination, and the trap-related dynamics with triplet exciton in a bilayer device of pentacene (Pen) and fullerene (C-60). Three MC effects in low-, moderate-, and high-fields were detected in the bilayer device at room temperature. Kinetic analysis of the low-field MC effect showed that the charge recombination yield at the Pen|C-60 interface is similar to 1%. Quantum mechanical simulations for dynamics of spin-carrying pairs following the conservation rule of spin angular momentum in recombination showed that the moderate- and high-field MC effects are caused by, respectively, the trap-related dynamics with triplet exciton and the singlet fission with a maximum yield of 52% in the layers. The quantitative information obtained by investigating the MC effect will contribute to the development of high-efficiency organic solar cells devices.

    DOI: 10.1021/jp508799j

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  • Electron Spin Polarization Transfer from Photogenerated Spin-Correlated Radical Pairs to a Stable Radical Observer Spin 査読

    Colvin Michael T, Carmieli Raanan, Miura Tomoaki, Richert Sabine, Gardner Daniel M, Smeigh Amanda L, Dyar Scott M, Conron Sarah M, Ratner Mark A, Wasielewski Michael R

    JOURNAL OF PHYSICAL CHEMISTRY A   117 ( 25 )   5314 - 5325   2013年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1021/jp4045012

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  • Supramolecular Control of the Spin-Dependent Dynamics of Long-Lived Charge-Separated States at the Micellar Interface As Studied by Magnetic Field Effect 査読

    Tomoaki Miura

    JOURNAL OF PHYSICAL CHEMISTRY B   117 ( 21 )   6443 - 6454   2013年5月

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    担当区分:筆頭著者, 最終著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Spin selectivity in long-lived charge separation at the micellar interface is studied using the magnetic field effect (MFE). An amphiphilic viologen is complexed with a nonionic surfactant to form a supramolecular acceptor cage, of which the size is controlled by the acceptor concentration, as confirmed by dynamic light scattering measurement. Photoinduced electron transfer (ET) from a guest polyaromatic molecule to the viologen moiety is observed spin-dependently with time-resolved fluorescence (trFL) and transient absorption (TA). A negative MFE on the radical yield is successfully observed, which indicates generation of singlet-born long-lived radical pair that is realized by supramolecular control of the donor-acceptor (D-A) distances. The dominance of the singlet-precursor MFE is sensitive to the acceptor concentration, which presumably affects the D-A distance as well as the cage size. However, theoretical analysis of the MFE gives large recombination rates of ca. 10(8) s(-1), which indicate the contribution of spin-allowed recombination of the pseudocontact radical pair generated by still active in-cage diffusion. Dependence of the viologen concentration and alkyl chain length on the recombination and escape dynamics is discussed in terms of precursor spin states and the microenvironments in the cage.

    DOI: 10.1021/jp401725f

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  • Manipulating Photogenerated Radical Ion Pair Lifetimes in Wirelike Molecules Using Microwave Pulses: Molecular Spintronic Gates 査読

    Tomoaki Miura, Michael R. Wasielewski

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   133 ( 9 )   2844 - 2847   2011年3月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We have studied spin-dependent charge transfer dynamics in wirelike, donor-bridge-acceptor (D-B-A)molecules comprising a phenothiazine (PTZ) donor, an oligo(2,7-fluorene) (FL(n)) bridge, and a perylene-3,4:9,10-bis(dicarboximide) (PDI) acceptor, PTZ-FL(3)-PDI (1) and PTZ-FL(4)-PDI (2), dissolved in the magnetic field-aligned nematic phase of 4-cyano-4&apos;-n-pentylbiphenyl (5CB) at 295 K. Time-resolved EPR spectroscopy using both continuous wave and pulsed microwaves shows that the photogenerated radical pairs (RPs), PTZ(+center dot)-FL(3)-PDI(-center dot) and PTZ(+center dot)-FL(4)-PDI(-center dot), recombine much faster from the singlet RP manifold than the triplet RP manifold. When a strong resonant microwave pi pulse is applied following RP photogeneration in 1 and 2, the RP lifetimes increase about 50-fold as indicated by electron spin-echo detection. This result shows that the RP lifetime can be greatly extended by rapidly switching off fast triplet RP recombination.

    DOI: 10.1021/ja110789q

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  • Magnetic Field-Induced Switching of the Radical-Pair Intersystem Crossing Mechanism in a Donor-Bridge-Acceptor Molecule for Artificial Photosynthesis 査読

    Michael T. Colvin, Annie Butler Ricks, Amy M. Scott, Amanda L. Smeigh, Raanan Carmieli, Tomoaki Miura, Michael R. Wasielewski

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   133 ( 5 )   1240 - 1243   2011年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A covalent, fixed-distance donor-bridge- acceptor (D-B-A) molecule was synthesized that upon photoexcitation undergoes ultrafast charge separation to yield a radical ion pair (RP) in which the spin-spin exchange interaction (2J) between the two radicals is sufficiently large to result in preferential RP intersystem crossing to the highest-energy RP eigenstate (T+1) at the 350 mT magnetic field characteristic of X-band (9.5 GHz) EPR spectroscopy. This behavior is unprecedented in covalent D-B-A molecules, and is evidenced by the time-resolved EPR (TREPR) spectrum at X-band of (3*) D-B-A derived from RP recombination, which shows all six canonical EPR transitions polarized in emission (e,e,e,e,e,e). In contrast, when the RP is photogenerated in a 3400 mT magnetic field, the TREPR triplet spectrum at W-band (94 GHz) of (3*) D-B-A displays the (a,e,e,a,a,e) polarization pattern characteristic of a weakly coupled RP precursor, similar to that observed in photosynthetic reaction center proteins, and indicates a switch to selective population of the lower-energy T-0 eigenstate.

    DOI: 10.1021/ja1094815

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  • Electron Spin Dynamics as a Controlling Factor for Spin-Selective Charge Recombination in Donor-Bridge-Acceptor Molecules 査読

    Tomoaki Miura, Amy M. Scott, Michael R. Wasielewski

    JOURNAL OF PHYSICAL CHEMISTRY C   114 ( 48 )   20370 - 20379   2010年12月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Photoinitiated charge separation and thermal charge recombination (CR) in a covalent donor-bridge-acceptor (D-B-A) system consisting of a perylene-3,4:9,10-bis(dicarboximide) (PDI) acceptor, 2,7-oligofluorene bridge (FLn), and phenothiazine donor (PTZ) (PTZ-FLn-PDI) have been shown to transition from superexchange to charge hopping mechanisms as the D-A distance increases. In work presented here, the spin-selective multiple CR pathways in PTZ-FLn-PDI are studied by a detailed analysis of the magnetic field effect (MFE) on the radical ion pair (RP) lifetime and triplet yield. A kinetic analysis of the MFE gives the spin-selective CR rates and the RP singlet-triplet (S-T) relaxation rates for n = 2-4. When n = 2 and 3, where the S-T splitting (2J) of the RP is large, slow S-T relaxation results in a kinetic bottleneck slowing the observed total CR rate at zero magnetic field. These results show that spin state mixing is an important controlling factor for CR reaction rates in these systems. The CR rate constant for the triplet RP (k(CRT)) obtained by MFE analysis is about 10 times faster than the corresponding rate for the singlet RP (k(CRS)) when n = 2-4, indicating that k(CRT) occurs near the maximum of the Marcus rate vs free energy dependence, whereas k(CRS) is deep in the inverted region. The distance dependence of both k(CRS) and k(CRT) is explained by the crossover from superexchange (n = 1 and 2) to distant independent thermal hopping (n = 3 and 4). A possible mechanism of the S-T relaxation is proposed based on S-T dephasing, which may be induced by fluctuations of 2J resulting from bridge torsional dynamics.

    DOI: 10.1021/jp103441n

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  • Photoreactions and Molecular Dynamics of Radical Pairs in a Reversed Micelle Studied by Time-Resolved Measurements of EPR and Magnetic Field Effect 査読

    Tomoaki Miura, Atsushi Kageyama, Sakiko Torii, Hisao Murai

    JOURNAL OF PHYSICAL CHEMISTRY B   114 ( 45 )   14550 - 14558   2010年11月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Photoreaction of N,N,N`,N`-tetramethyl-1,4-phenylenediamine (TMPD) in an aerosol OT (AOT) reversed micelle (RM) is studied by time-resolved EPR (tr-EPR) and the transient absorption detected magnetic field effect (MFE) Tr-EPR and transient absorption spectra indicate electron transfer from a highly excited triplet state of TMPD to the AOT headgroup regardless of W = [H(2)O]/[AOT] values from 0 to 40 Noticeable MFEs on the yield of TMPD cation radical (TMPD(+)) are observed at W &gt; 0 and maximized at W similar to 10 The dynamics of TMPD(+) in the bound water region of the RM has been precisely analyzed by theoretical analysis of time-resolved magnetically affected reaction yield (MARY) spectra The simulation of the MARY spectra indicates that two kinds of radical pairs exist, both of which are composed of an AOT alkyl radical and TMPD(+) One system has TMPD(+) strongly bound to the anionic interface, where the radical pair shows very slow relaxation and recombination Another system has TMPD(+) diffusing in the bound water, which shows a smaller diffusion coefficient than that in bulk water by 1 order of magnitude In the larger water pool (W &gt; 15), the spin correlated radical pair of the hydrated electron and TMPD(+) generated by photoionization is observed by tr-EPR The ionization reaction is followed by electron attachment to the AOT headgroup and generation of the sulfite radical However these radical pairs are not thought to contribute significantly to the observed MFEs Spin multiplicities of the precursor state and recombination products have been discussed from the different sign of J values for the radical pairs at larger W

    DOI: 10.1021/jp102300z

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  • Time-Resolved EPR Studies of Charge Recombination and Triplet-State Formation within Donor-Bridge-Acceptor Molecules Having Wire-Like Oligofluorene Bridges 査読

    Tomoaki Miura, Raanan Carmieli, Michael R. Wasielewski

    JOURNAL OF PHYSICAL CHEMISTRY A   114 ( 18 )   5769 - 5778   2010年5月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    Spin-selective charge recombination of photogenerated radical ion pairs within a series of donor-bridge-acceptor (D-B-A) molecules, where D = phenothiazine (PTZ), B = oligo(2,7-fluorenyl), and A = perylene-3,4: 9,10-bis(dicarboximide) (PDI), PTZ-FL(n)-PDI, where n = 1-4 (compounds 1-4), is studied using time-resolved electron paramagnetic resonance (TREPR) spectroscopy in which the microwave source is either continuous-wave or pulsed. Radical ion pair TREPR spectra are observed for 3 and 4 at 90-294 K, while the neutral triplet state of PDI ((3)*PDI) is observed at 90-294 K for 2-4 and at 90 K for 1. (3)*PDI is produced by three mechanisms, as elucidated by its zero-field splitting parameters and spin polarization pattern. The mechanisms are spin-orbit-induced intersystem crossing (SO-ISC) in PDI aggregates, direct spin-orbit charge-transfer intersystem crossing (SOCT) from the singlet radical pair within 1, and radical pair intersystem crossing (RP-ISC) as a result of S-T(0) mixing of the radical ion pair states in 2-4. The temperature dependence of the spin-spin exchange interaction (2J) shows a dramatic decrease at low temperatures, indicating that the electronic coupling between the radical ions decreases due to an increase in the average fluorene-fluorene dihedral angle at low temperatures. The charge recombination rates for 3 and 4 decrease at low temperature, but that for 2 is almost temperature-independent. These results strongly suggest that the dominant mechanism of charge recombination for n &gt;= 3 is incoherent thermal hopping, which results in wire-like charge transfer.

    DOI: 10.1021/jp101523n

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  • Competitive Electron Transfer and Enhanced Intersystem Crossing in Photoexcited Covalent TEMPO-Perylene-3,4:9,10-bis(dicarboximide) Dyads: Unusual Spin Polarization Resulting from the Radical-Triplet Interaction 査読

    Michael T. Colvin, Emilie M. Giacobbe, Boiko Cohen, Tomoaki Miura, Amy M. Scott, Michael R. Wasielewski

    JOURNAL OF PHYSICAL CHEMISTRY A   114 ( 4 )   1741 - 1748   2010年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A stable 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) radical was covalently attached at its 4-position to the imide nitrogen atom of a perylene-3,4:9,10-bis(dicarboximide) (PDI) to produce TEMPO-PDI, 1, having a well-defined distance and orientation between TEMPO and PDI. Transient optical absorption experiments in toluene following selective photoexcitation of the PDI chromophore in TEMPO-PDI show that enhanced intersystem crossing occurs with tau = 45 +/- 1 ps, resulting in formation of TEMPO-(3)*PDI, while the same experiment in THF shows that the electron-transfer reaction TEMPO-(1)*PDI -&gt; TEMPO(+)*-PDI(-)* occurs with tau = 1.2 +/- 0.2 ps and thus competes effectively with enhanced intersystem crossing. Time-resolved EPR (TREPR) spectroscopy on the photogenerated three-spin system TEMPO-(3)*PDI in toluene at 295 K initially shows a broad signal assigned to spin-polarized 3*PDI, which thermalizes at longer times and is accompanied by formation of an emissively polarized TEMPO radical. No signals are observed in THF at 295 K. The TREPR spectrum of TEMPO-(3)*PDI at 85 K in toluene shows an emissive/absorptive signal due to TEMPO and a broad triplet signal due to 3*PDI having a spin polarization pattern characteristic of overpopulation of its T(0) sublevel. This unusual spin polarization pattern does not result from radical pair intersystem crossing because electron transfer does not occur at 85 K. The observed spin polarization of (3)*PDI cannot be readily explained by mechanisms discussed previously, leading us to propose a new spin polarization mechanism. which requires that the radical and attached triplet are in the weak exchange regime.

    DOI: 10.1021/jp909212c

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  • Spin-Selective Charge Transport Pathways through p-Oligophenylene-Linked Donor-Bridge-Acceptor Molecules 査読

    Amy M. Scott, Tomoaki Miura, Annie Butler Ricks, Zachary E. X. Dance, Emilie M. Giacobbe, Michael T. Colvin, Michael R. Wasielewski

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   131 ( 48 )   17655 - 17666   2009年12月

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    記述言語:英語   出版者・発行元:AMER CHEMICAL SOC  

    A series of donor-bridge-acceptor (D-B-A) triads have been synthesized in which the donor, 3,5-dimethyl-4-(9-anthracenyl)julolidine (DMJ-An), and the acceptor, naphthalene-1,8:4,5-bis(dicarboximide) (NI), are linked by p-oligophenylene (Ph-n) bridging units (n = 1-5). Photoexcitation of DMJ-An produces DMJ(+center dot)-An(-center dot) quantitatively, so that An(-center dot) acts as a high potential electron donor, which rapidly transfers an electron to NI yielding a long-lived spin-coherent radical ion pair (DMJ(+center dot)-An-Ph-n-NI-center dot). The charge transfer properties of 1-5 have been studied using transient absorption spectroscopy, magnetic field effects (MFEs) on radical pair and triplet yields, and time-resolved electron paramagnetic resonance (TREPR) spectroscopy. The charge separation (CS) and recombination (CR) reactions exhibit exponential distance dependencies with damping coefficients of beta = 0.35 angstrom(-1) and 0.34 angstrom(-1), respectively. Based on these data, a change in mechanism from superexchange to hopping was not observed for either process in this system. However, the CR reaction is spin-selective and produces the singlet ground state and both (3)*An and (3)*NI. A kinetic analysis of the MFE data shows that superexchange dominates both pathways with beta = 0.48 angstrom(-1) for the singlet CR pathway and beta = 0.35 angstrom(-1) for the triplet CR pathway. MFEs and TREPR experiments were used to measure the spin-spin exchange interaction, 2J, which is directly related to the electronic coupling matrix element for CR, V-CR(2). The magnitude of 2J also shows an exponential distance dependence with a damping coefficient alpha = 0.36 angstrom(-1), which agrees with the P values obtained from the distance dependence for triplet CR. These results were analyzed in terms of the bridge molecular orbitals that participate in the charge transport mechanism.

    DOI: 10.1021/ja907625k

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  • Real-time observation of the spin-state mixing process of a micellized radical pair in weak magnetic fields by nanosecond fast field switching 査読

    Tomoaki Miura, Hisao Murai

    JOURNAL OF PHYSICAL CHEMISTRY A   112 ( 12 )   2526 - 2532   2008年3月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The singlet-triplet spin-state mixing process of a singlet-born radical pair confined in a sodium dodecyl sulfate (SDS) micelle was studied by observing the nanosecond switched external magnetic field (SEMF) effect on the transient absorption signals. A long-lived singlet radical pair is generated by the photoinduced bond cleavage reaction of tetraphenylhydrazine in an SDS micelle. Application of off-on type SEMF results in the increase of the free radical yield contrary to the decrease produced by an applied static magnetic field. The S-T mixing process in low magnetic field was observed by means of a delay-shift SEMF experiment. Observed incoherent mixing processes are explained in terms of the interplay between coherent hyperfine interaction and fast dephasing processes caused by the fluctuation of electron-spin interactions. Singlet-triplet and triplet-triplet dephasing rate constants are determined independently to be 2 x 10(8) and 0.2 x 10(8) s(-1), respectively, by a simulation based on a modified single-site Liouville equation. This is the first direct observation of the incoherent spin-state mixing process at magnetic fields comparable to the hyperfine interactions of the radical pair.

    DOI: 10.1021/jp077505x

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  • A practical simulation and a novel insight to the magnetic field effect on a radical pair in a micelle 査読

    Kiminori Maeda, Tomoaki Miura, Tatsuo Arai

    MOLECULAR PHYSICS   104 ( 10-11 )   1779 - 1788   2006年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TAYLOR & FRANCIS LTD  

    The spin mixing process of a radical pair in a micelle in a low magnetic field is investigated by transient absorption detected MARY spectra. In a system comprising the radical pair generated by photoreaction of 2-methyl-1,4-naphthoquinone in sodium dodecylsulfate micelle, two techniques were applied: time resolved MARY spectra and pulsed MARY spectra. In order to analyse the results, a practical calculation method that lends itself to the simulation of experimental results has been developed. In the calculation, a semi-classical model was used for the evaluation of the hyperfine mechanism (HFM) in the single-site Liouville equation in which one can take spin relaxation and dephasing phenomena into account. The interrelation between the HFM and relaxation mechanism (RM) was discussed. A new insight into the HFM induced spin mixing process, which is assisted by fast spin dephasing phenomena, is proposed. This mechanism is important for the MARY spectral shape and connects the HFM and RM smoothly.

    DOI: 10.1080/14767050600588106

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  • The spin mixing process of a radical pair in low magnetic field observed by transient absorption detected nanosecond pulsed magnetic field effect 査読

    Tomoaki Miura, Kiminori Maeda, Tatsuo Arai

    JOURNAL OF PHYSICAL CHEMISTRY A   110 ( 12 )   4151 - 4156   2006年3月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    The spin mixing process of the radical pair in the sodium dodecyl sulfate (SDS) micelle is studied by using a novel technique nanosecond Pulsed magnetic field effect oil transient absorption. We have developed the equipment for a nanosecond pulsed magnetic field and observed its effect on the radical pair reaction. A decrease of the free radical yield by a reversely directed pulsed magnetic field that cancels static field is observed, and the dependence on its magnitude, which is called pulsed MARY (magnetic field effect on reaction yield) spectra, is studied. The observed spectra reflect the spin mixing in 50-200 ns and show clear time evolution. Theoretical simulation of pulsed MARY spectra based on a single site modified Liouville equation indicates that the fast spin dephasing processes induced by the modulation of electron -electron spin interaction by molecular reencounter affect to the coherent spin mixing by a hyperfine interaction in a low magnetic field.

    DOI: 10.1021/jp056488d

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  • Spin dynamics of the radical pair in a low magnetic field studied by the transient absorption detected magnetic field effect on the reaction yield and switched external magnetic field 査読

    Toshiaki Suzuki, Tomoaki Miura, Kiminori Maeda, Tatsuo Arai

    JOURNAL OF PHYSICAL CHEMISTRY A   109 ( 44 )   9911 - 9918   2005年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    xxThe spin dynamics of the radical pair generated from the photocleavage reaction of (2,4,6-trimethylbenzoyl)-diphenylphosphine oxide (TMDPO) in micellar solutions was studied by the time-resolved magnetic field effect (MFE) on the transient absorption (TA) and by a novel technique, absorption detected switched external magnetic field (AD-SEMF). Thanks to the large hyperfine coupling constant (A = 38 mT), a characteristic negative MFE on the radical yield was observed at a magnetic field lower than 60 mT whereas a positive effect due to the conventional hyperfine (HFM) and relaxation mechanisms (RM) was observed at higher magnetic field. The negative effect can be assigned to the mechanism "so-called" low field affect (LFE) mechanism and has been analyzed thoroughly using a model calculation incorporating a fast spin dephasing process. The time scale of the spin mixing process of LFE Studied by AD-SEMF is shorter than the lifetime 0 of the recombination kinetics of the radical pair. These results indicate that the LIFE originates from the coherent spin motion. This can be interfered from the fast spin dephasing caused by electron spin interaction fluctuations.

    DOI: 10.1021/jp053989q

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  • Effect of coulomb interaction on the dynamics of the radical pair in the system of flavin mononucleotide and hen egg-white lysozyme (HEWL) studied by a magnetic field effect 査読

    Tomoaki Miura, Kiminori Maeda, Tatsuo Arai

    JOURNAL OF PHYSICAL CHEMISTRY B   107 ( 26 )   6474 - 6478   2003年7月

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    担当区分:筆頭著者   記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    A large magnetic field effect (MFE) up to 13% of the yield of the free radical formation is found in the photoinduced electron-transfer reaction from the tryptophan residue of the hen egg-white lysozyme (HEWL) to the flavin mononucleotide, (FMN). The magnetic field effect is special in the water solution of FMN, and that is reduced to 5-7% by the addition of sodium chloride to the solution and in the system of riboflavin. The MFE up to 13% coincides with the appearance of the fast quenching process of the excited singlet state. The large MFE is attributed to association by Coulomb interaction between the ionic phosphate group of FMN and the cationic surface of the protein molecule.

    DOI: 10.1021/jp034068n

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▶ 全件表示

講演・口頭発表等

  • Carrier and Spin Dynamics in Organic Photovoltaic Thin Films Studied by Simultaneous Optical and Electrical Detection 招待

    Tomoaki Miura, Sou Kobayashi, Naoya Muramatsu, Mariko Yatsushiro, Tadaaki Ikoma

    17th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena  2022年8月 

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    記述言語:英語  

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  • 分光-電気伝導同時計測を用いた有機半導体薄膜 キャリアダイナミクスの解明 招待

    三浦 智明, 生駒 忠昭

    第24 回ESR フォーラム研究会  2021年9月 

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    会議種別:口頭発表(招待・特別)  

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  • Magnetic Field Effects on Organic Photovoltaic Thin Films as Studied by Simultaneous Optical-Electrical Transient Measurement

    Tomoaki Miura, So Kobayashi, Mariko Yatsushiro, Tadaaki Ikoma

    Joint Conference of 22nd International Society of Magnetic Resonance Conference, the 9th Asia-Pacific NMR Symposium, the 60th Annual Meeting of the Nuclear Magnetic Resonance Society of Japan (2021), and the 60th Annual Meeting of the Society of Electron Spin Science and Technology  2021年8月 

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    記述言語:英語  

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  • 可視近赤外過渡吸収-過渡光電流同時観測法を用いた有機半導体薄膜の光キャリア動力学研究 招待

    三浦 智明

    光化学協会 光化学応用講座2019 「時間分解分光の新展開:原理から先端応用まで」  2019年12月 

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    会議種別:シンポジウム・ワークショップ パネル(指名)  

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  • Charge Career and Spin Dynamics in Organic Semiconductor Thin Films Studied by Simultaneous Measurement of Transient Optical Absorption and Photocurrent Signals

    Tomoaki Miura, Ryoya Akiyama, Akiha Yamada, Sou Kobayashi, Tadaaki Ikoma

    16th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena  2019年8月 

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    記述言語:英語  

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  • Gigantic Magnetic Field Effect on Long-Lived Charge Separated States Created at a Nonionic Vesicle Interface

    Tomoaki Miura, Kiminori Maeda, Tadaaki Ikoma

    15th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena  2017年9月 

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    記述言語:英語  

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  • Recent Development in Spin Chemistry of Photo-generated Radical Pairs Confined in Surfactant-based Soft Nanomaterials 招待

    Tomoaki Miura, Kiminori Maeda, Hisao Murai, Tadaaki Ikoma

    Asia-Pacific EPR/ESR Symposium 2016  2016年8月 

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    記述言語:英語  

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  • Dynamic and Electronic Characteristics of Photogenerated Radical Pairs Revealed by Real time Observation of the Spin Dynamics 招待

    Tomoaki Miura

    Joint Conference of 9th Asia-Pacific EPR/ESR Society Symposium, 1st International EPR (ESR) Society Symposium, 53rd Annual Meeting of the Society of Electron Spin Science and Technology, 2014  2014年11月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • 電子スピンダイナミクスの実時間観測による光反応中間体ラジカル対の研究 招待

    三浦 智明

    第52回電子スピンサイエンス学会年会  2013年10月 

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    会議種別:口頭発表(招待・特別)  

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  • Supramolecular Control of Spin-Dependent Electron Transfer Dynamics in Micellar Supercages as Studied by Magnetic Field Effects

    Tomoaki Miura, Kiminori Maeda, Hisao Murai, Tadaaki Ikoma

    13th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena  2013年4月 

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    記述言語:英語  

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  • Spin Dynamics of a Long-lived Singlet-BornRadical Ion Pair Created in an Acceptor-adsorbed Micellar Super-cage

    Tomoaki Miura

    2nd International Symposium on Electron Spin Science  2012年7月 

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    記述言語:英語  

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  • Extracting Molecular Motion That Gates Charge Transport among Molecular Wires from the Spin Dynamics of the Radical Pair

    Tomoaki Miura, Michael R. Wasielewski

    The 12th International Symposium on Spin and Magnetic Field Effects in Chemistry and Related Phenomena  2011年5月 

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    記述言語:英語  

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  • Spin Dynamics of Long-Lived Radical Pairs in Weak Magnetic Fields Studied by Nanosecond Pulsed Magnetic Field Effect

    Tomoaki Miura, Hisao Murai

    A Joint Conference of the International Symposium on Electron Spin Science and the 46th Annual Meeting of the Society of Electron Spin Science and Technology  2007年11月 

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    記述言語:英語  

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  • Real Time Observation of the Spin Mixing Process of a Singlet Radical Pair in a Micelle by Means of Nanosecond Magnetic Field Switching

    Tomoaki Miura, Hisao Murai

    Sendai-Berlin-Novosibirsk Joint Seminar on Advanced EPR  2006年8月 

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    記述言語:英語  

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受賞

  • 第5回学長賞(若手教員研究奨励)

    2018年11月   新潟大学   Magnetic Control of the Charge-Separated State Lifetime Realized by Covalent Attachment of aPlatinum Complex

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  • Young Investigator Award

    2014年   The International EPR (ESR) Society  

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  • 電子スピンサイエンス学会奨励賞

    2013年11月   電子スピンサイエンス学会   電子スピンダイナミクスの実時間観測による光反応中間体ラジカル対の研究

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  • 第88回日本化学会春期年会 学生講演賞

    2008年   日本化学会   長寿命ラジカル対の磁場効果に対する分子拡散運動の効果

    三浦 智明, 村井 久雄

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  • 優秀講演賞

    2006年   電子スピンサイエンス学会   過渡吸収検出ナノ秒磁場スイッチング法を用いた一重項ラジカル対スピンダイナミクスの解析

    三浦 智明, 村井 久雄

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  • Best Poster Award, 2nd Sendai-Berlin Joint Seminar on Advanced ESR

    2004年   The Effect of Nanosecond Pulsed Magnetic Field on the Spin Dynamics of Radical Pairs.

    Tomoaki Miura, Kiminori Maeda, Tatsuo Arai

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共同研究・競争的資金等の研究

  • 有機半導体薄膜におけるキャリア動力学の実時間観測と光スピントロニック制御

    研究課題/領域番号:22K05048

    2022年4月 - 2025年3月

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    三浦 智明

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    配分額:4160000円 ( 直接経費:3200000円 、 間接経費:960000円 )

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  • 分光・電気伝導同時実時間観測による有機半導体薄膜光物性の解明

    研究課題/領域番号:19K05399

    2019年4月 - 2023年3月

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    三浦 智明

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    配分額:4160000円 ( 直接経費:3200000円 、 間接経費:960000円 )

    標準的なP3HT:PCBMバルクヘテロ薄膜を用いた有機薄膜太陽電池素子について、光生成電荷キャリアの消滅過程を詳細に解析した。開発した過渡光吸収-過渡光電流同時計測によって得られる電流信号と分光信号の除算から平均キャリア移動度の時間変化が得られた。ここで求まる平均移動度に加え、電極取り出し時間から求まる従来型のTOF移動度を同一素子・同一条件で得ることに成功した。2つの方法で得られた移動度の温度依存性の比較から、TOF移動度は活性化エネルギーが小さく、移動準位近辺のキャリアを選択的に評価しているのに対し、トラップキャリアも含めた全平均移動度は顕著に大きな活性化エネルギーを示し、深いトラップに捕捉されたキャリアが薄膜中に多数存在していることが明らかになった。このことは従来の電気的移動度計測法では、非常にマイナーな高移動性キャリアを選択的に評価してしまう危険性があり、電流にほとんど寄与しないトラップキャリアの寄与を正しく評価できないことを如実に示している。本手法は有機薄膜太陽電池素子中に存在する、移動度分布をもったキャリアの全体像を実時間的に評価できる有用な手法である。
    また、過渡光吸収、過渡光電流の時間変化がべき乗測に従って減衰することに着目し、共同研究にて理論計算との比較を行った。キャリア再結合の寄与は無視した計算ではあるが、今回観測された時間変化は従来のホッピング理論でおおむね説明できることがあきらかとなった。
    これと並行し、発光性サンプルの測定にも対応できるように、過渡吸収信号から発光信号を差し引く測定プログラム改良を行い、色素ドープ導電性薄膜素子において10 nsスケールの再結合過程に対する磁場効果の観測に成功した。

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  • 非イオン性二分子膜の光磁気機能材料化へ向けた界面電子移動の研究

    研究課題/領域番号:15K05384

    2015年10月 - 2019年3月

    制度名:科学研究費助成事業

    研究種目:基盤研究(C)

    提供機関:日本学術振興会

    三浦 智明, 生駒 忠昭, 前田 公憲

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    配分額:4680000円 ( 直接経費:3600000円 、 間接経費:1080000円 )

    ニオソームは安価な界面活性剤分子を用いて水中で簡便に作製できる二分子膜カプセルであり、生体内のドラッグデリバリー材料として近年注目を集めている。本研究では光と磁場で薬剤放出を制御できるドラッグデリバリーや、磁場によって効率を制御できる人工光合成などの新しい材料を開発するための基礎研究として、色素とビタミン類を埋め込んだニオソームを新たに開発し、光照射による酸化還元、これにより生じた長寿命な「電荷分離状態」、さらにその磁場効果を詳細に調べた。ここから人工光合成において重要となる多段階の電子伝達や、ドラッグデリバリーにおいて重要となる光による膜形態変化を示す結果を得ることができた。

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  • 電子スピンをプローブとした二分子膜界面束縛水の電子伝達機構解明

    研究課題/領域番号:25810009

    2013年4月 - 2016年3月

    制度名:科学研究費助成事業

    研究種目:若手研究(B)

    提供機関:日本学術振興会

    三浦 智明

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    配分額:4420000円 ( 直接経費:3400000円 、 間接経費:1020000円 )

    ミセルや二分子膜といった界面活性剤によって水中に構成される集合体内で起こる光誘起電子移動(酸化還元)反応に関する基礎研究を行った。ミセル界面に3種類の分子を用いた2段階電子移動系を構築し、分子拡散に基づく長距離・長寿命電荷分離状態の形成に成功した。また、二分子膜カプセル界面において長寿命電荷分離状態を形成する系を見出した。この系では200 mT程度の磁場印加で電荷分離状態の過渡濃度が倍増する巨大な磁場効果が見出された。これらの成果は生体膜における電子移動機構の理解や、安価な界面活性剤を用いた光・磁気機能性材料の開発において有用な知見を与えると考えられる。

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  • 有機色素ナノ粒子の光エレクトロニクス物性と電子移動

    研究課題/領域番号:23750022

    2011年 - 2012年

    制度名:科学研究費助成事業

    研究種目:若手研究(B)

    提供機関:日本学術振興会

    三浦 智明

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    配分額:4550000円 ( 直接経費:3500000円 、 間接経費:1050000円 )

    次世代光機能性材料として注目されている有機色素ナノ集合体の光および電子的物性に関する基礎的な知見を得るために、電子供与性ポルフィリン‐電子受容性ナフタレンジイミド(NDI)との間の会合体形成および電子移動に関する研究を行った。水溶液中にてアニオン性NDIとカチオン性ポルフィリンとの間で10の5乗を超える高効率な会合定数が見いだされた。分子構造および環境場依存性から、会合体形成は主に疎水性相互作用によって引き起こされ、クーロン力の影響を強く受けていることが明らかとなった。また、分光研究から会合体中におけるピコ秒オーダー以上の高速電子移動および逆電子移動が明らかとなった。

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担当経験のある授業科目

  • 化学コロキウム

    2022年
    -
    現在
    機関名:新潟大学

  • 理学スタディ・スキルズ

    2021年
    機関名:新潟大学

  • 化学基礎実習b

    2017年
    -
    現在
    機関名:新潟大学

  • 化学基礎実習a

    2017年
    -
    現在
    機関名:新潟大学

  • 理学スタディ・スキルズ

    2017年
    -
    2021年
    機関名:新潟大学

  • Chemistry TodayⅠ

    2015年
    機関名:新潟大学

  • 量子化学演習

    2014年
    -
    現在
    機関名:新潟大学

  • 化学実験

    2014年
    -
    2016年
    機関名:新潟大学

  • 物理化学実験

    2013年
    -
    現在
    機関名:新潟大学

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