2022/11/25 更新

写真b

ミツイ マサアキ
三井 正明
MITSUI Masaaki
*大学が定期的に情報更新している項目(その他は、researchmapの登録情報を転載)
所属*
理学部 化学科
理学研究科 化学専攻 博士課程後期課程
理学研究科 化学専攻 博士課程前期課程
職名*
教授
学位
博士(理学) ( 京都大学 )
連絡先
メールアドレス
研究テーマ*
  • 光物理化学、ナノ物質科学。独自に開発したレーザー顕微分光計測装置を用いて、1分子(1粒子)レベルの極限的な分光研究を行っている。有機色素、超分子錯体、金属クラスター、有機・無機ナノ結晶などの多様なナノ物質群を研究対象とし、それらの光物性の発現メカニズムや励起状態(励起子)ダイナミクスに関する理解を推し進め、材料応用・デバイス応用へとつなげていくことを目指している。

  • 研究キーワード
  • 光物理化学

  • 励起状態・励起子

  • 光機能性分子・多重極子発色団

  • 配位子保護金属クラスター

  • 単一分子分光

  • 三重項-三重項消滅フォトンアップコンバージョン

  • 色素増感太陽電池

  • 学内職務経歴*
    • 2014年4月 - 現在 
      理学部   化学科   教授
    • 2014年4月 - 現在 
      理学研究科   化学専攻 博士課程前期課程   教授
    • 2014年4月 - 現在 
      理学研究科   化学専攻 博士課程後期課程   教授
     

    研究分野

    • ナノテク・材料 / 基礎物理化学  / 光物理化学

    • ナノテク・材料 / 機能物性化学  / 光エネルギー変換

    • ナノテク・材料 / ナノ構造化学  / ナノ物質・クラスター

    • ナノテク・材料 / 機能物性化学  / フォトン・アップコンバージョン

    経歴

    • 2014年4月 - 現在 
      立教大学   理学研究科 化学専攻博士課程前期課程   教授

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    • 2014年4月 - 現在 
      立教大学   理学研究科 化学専攻博士課程後期課程   教授

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    • 2014年4月 - 現在 
      立教大学   理学部 化学科   教授

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    • 2013年4月 - 2014年3月 
      静岡大学大学院   理学研究科   准教授

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    • 2007年10月 - 2013年3月 
      静岡大学   理学部   准教授

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    • 2010年4月 - 2010年9月 
      東京工業大学   非常勤講師

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    • 2006年4月 - 2007年9月 
      慶應義塾大学   理工学部   専任講師

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    • 2002年4月 - 2006年3月 
      慶應義塾大学   理工学部   助手

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    • 2000年8月 - 2002年3月 
      慶應義塾大学   理工学部   研究員

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    • 2000年4月 - 2000年7月 
      京都大学   理学部   研修員

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    • 1997年4月 - 2000年3月 
      日本学術振興会特別研究員   (DC1)

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    学歴

    • 2000年7月 
      京都大学 博士(理学)取得

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    • 1997年4月 - 2000年3月 
      京都大学   大学院理学研究科   化学専攻 単位取得退学

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      国名: 日本国

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    • 1995年4月 - 1997年3月 
      東京工業大学   大学院理工学研究科   化学専攻 修了

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      国名: 日本国

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    • 1991年4月 - 1995年3月 
      東京工業大学   理学部   化学科 卒業

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      国名: 日本国

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    委員歴

    • 2022年3月 - 現在 
      文部科学省   科学技術・科学技術動向研究センター専門調査員

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    • 2021年4月 - 2022年3月 
      文部科学省   科学技術・科学技術動向研究センター専門調査員

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    • 2021年8月 - 2021年9月 
      分子科学会   第15回分子科学討論会・優秀講演賞代表選考委員

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      団体区分:学協会

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    • 2020年4月 - 2021年3月 
      文部科学省   科学技術・科学技術動向研究センター専門調査員

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    • 2019年4月 - 2020年3月 
      文部科学省   科学技術・科学技術動向研究センター専門調査員

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    • 2019年8月 - 2019年9月 
      分子科学会   第13回分子科学討論会・優秀講演賞代表選考委員

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      団体区分:学協会

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    • 2018年4月 - 2019年3月 
      文部科学省   科学技術・科学技術動向研究センター専門調査員

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    • 2017年4月 - 2018年3月 
      文部科学省   科学技術・科学技術動向研究センター専門調査員

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    • 2016年4月 - 2017年3月 
      文部科学省   科学技術・科学技術動向研究センター専門調査員

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    • 2017年 
      日本学術振興会   卓越研究員候補者選考員会書面審査員

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    • 2013年4月 - 2015年3月 
      分子科学会   企画委員会委員

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      団体区分:学協会

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    • 2013年 - 2014年 
      日本学術振興会   科学研究費審査委員 第1段階審査(書面審査)委員

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    • 2010年4月 - 2012年3月 
      日本化学会   東海支部代議員

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      団体区分:学協会

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    • 2006年4月 - 2008年3月 
      ナノ学会   編集委員

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      団体区分:学協会

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    •  
      独立行政法人日本学術振興会   特別研究員等審査会専門委員/国際事業委員会書面審査委員・書面評価委員

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    受賞

    • 2022年10月  
      光化学協会  2022年光化学討論会 優秀学生発表賞(ポスター)  「発光体配位子保護 Au-Cu 合金クラスターを増感剤に用いた高効率フォトンアップコンバージョン」
       
      有馬大地,三井

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    • 2022年5月  
      ナノ学会  第20回大会ナノ学会 若手優秀ポスター発表賞  「配位子保護Au-Cu合金クラスターにおける励起状態緩和の全容解明 - 光アップコンバージョン解析によるアプローチ -」
       
      有馬大地, 三井

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    • 2021年9月  
      分子科学会  第15回分子科学討論会 分子科学会優秀ポスター賞  配位子保護金クラスターを三重項増感剤に用いた光アップコンバージョン
       
      和田悠幹, 三井

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    • 2016年11月  
      第35回 固体・表面光化学討論会  ポスター賞  CH3NH3PbI3を基盤としたヘテロ層構造の発光顕微分光
       
      齋藤祐太, 三井

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    • 2016年11月  
      第35回 固体・表面光化学討論会  ポスター賞  D-π-A-π-D四重極子色素の単一分子分光 : 発光特性に対する固体環境効果
       
      水上俊成, 三井

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    • 2006年3月  
      日本化学会  日本化学会進歩賞  巨大な分子クラスターの生成法の開発とその電子構造の解明
       
      三井正明

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      受賞区分:国内学会・会議・シンポジウム等の賞 

      受賞国:日本国

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    • 2005年9月  
      分子構造総合討論会  分子構造総合討論会奨励賞  分子クラスターにおける固体-液体類似相の共存
       
      三井正明

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      受賞区分:国内学会・会議・シンポジウム等の賞 

      受賞国:日本国

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    論文

    • Charge-Transfer-Mediated Mechanism Dominates Oxygen Quenching of Ligand-Protected Noble-Metal Cluster Photoluminescence 査読有り

      Masaaki Mitsui, Daichi Arima, Atsuki Uchida, Kouta Yoshida, Yamato Arai, Kakeru Kawasaki, Yoshiki Niihori

      The Journal of Physical Chemistry Letters13   9272 - 9278   2022年9月

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

      DOI: 10.1021/acs.jpclett.2c02568

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    • On the Origin of Photoluminescence Enhancement in Biicosahedral AgxAu25-x Nanoclusters (x=0-13) and Their Application to Triplet-Triplet Annihilation Photon Upconversion 査読有り

      Masaaki Mitsui, Daichi Arima, Yuki Kobayashi, Eunji Lee, Yoshiki Niihori

      ADVANCED OPTICAL MATERIALS   2022年7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:WILEY-V C H VERLAG GMBH  

      Numerous reports hitherto show that the photoluminescence (PL) properties of metal nanoclusters (NCs) can be enhanced by alloying the metal cores. In particular, biicosahedral [AgxAu25-x(PPh3)(10)(SR)(5)Cl-2](2+) (abbreviated as AgxAu25-x hereafter; with PPh3 = triphenylphosphine; SR = thiolate ligand) NCs attract significant attention because their PL quantum yield is improved by 200 times when 13 Au atoms are replaced with Ag atoms (x = 13). In this contribution, the origin of the PL in the AgxAu25-x system and its remarkable enhancement are investigated on the basis of spectroscopic investigations of the PL behavior and its quenching by an organic fluorophore, finding that (i) the observed PL of AgxAu25-x is phosphorescent; (ii) not only Ag13Au12 but also Ag12Au13 NCs contribute to the PL; and (iii) replacing the central vertex atom of the biicosahedron with an Ag atom causes a blue shift of the triplet states, which suppresses the T-1-S-0 intersystem crossing and enhances the phosphorescence emission. Additionally, the results of single-particle PL spectroscopy and defocused imaging with rotation of linearly polarized excitation light reveal that the phosphorescence transition dipole moment of Ag13Au12 exists in the long axis direction of the biicosahedron. Furthermore, the AgxAu25-x NCs can sensitize molecular triplets and efficiently induce red-to-blue photon upconversion via triplet-triplet annihilation.

      DOI: 10.1002/adom.202200864

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    • Evidence for triplet-state-dominated luminescence in biicosahedral superatomic molecular Au-25 clusters 査読有り

      Masaaki Mitsui, Yuki Wada, Ryoto Kishii, Daichi Arima, Yoshiki Niihori

      NANOSCALE14 ( 22 )   2022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:ROYAL SOC CHEMISTRY  

      In photoluminescence (PL) quenching and triplet fusion upconversion experiments with fluorescent organic-molecule quenchers, it was revealed that a rod-shaped, phosphine- and thiolate-protected biicosahedral Au-25 cluster (a representative di-superatomic molecule) exhibits only phosphorescence, not fluorescence, at room temperature with an intersystem crossing quantum yield of almost 100%. By virtue of these photophysical properties, this cluster can be used as a triplet sensitizer that undergoes direct singlet-triplet transitions in the near-infrared (NIR) region (730-900 nm), inducing photon upconversion from NIR to visible light.

      DOI: 10.1039/d2nr00813k

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    • Unravelling the origin of dual photoluminescence in Au<sub>2</sub>Cu<sub>6</sub> clusters by triplet sensitization and photon upconversion 招待有り 査読有り

      Daichi Arima, Yoshiki Niihori, Masaaki Mitsui

      Journal of Materials Chemistry C10 ( 12 ) 4597 - 4606   2022年

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      担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Royal Society of Chemistry (RSC)  

      Ligand-protected Au<sub>2</sub>Cu<sub>6</sub> cluster exhibits not only fluorescence but also phosphorescence at room temperature and serves as a triplet sensitizer in triplet fusion upconversion.

      DOI: 10.1039/d1tc04591a

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    • Excited-State Symmetry Breaking in a Multiple Multipolar Chromophore Probed by Single-Molecule Fluorescence Imaging and Spectroscopy 査読有り

      Masaaki Mitsui, Yasushi Takakura, Kazuya Hirata, Yoshiki Niihori, Yutaka Fujiwara, Kenji Kobayashi

      JOURNAL OF PHYSICAL CHEMISTRY B125 ( 35 ) 9950 - 9959   2021年9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  

      Excited-state symmetry breaking (ESB) has attracted much attention because it is often observed in symmetric multipolar chromophores designed as two-photon absorption/emission materials. Herein, we report an ensemble and single-molecule fluorescence imaging and spectroscopy investigation of ESB in hexakis[4-(p-dioctylaminostyryl)phenylethynyl]benzene-(DB6), a two-photon absorber possessing a C-6-symmetric pi-D-6 structure (pi = hexaethynylbenzene, D = (p-dioctylaminostyryl)-phenyl group) consisting of three equivalent D-pi-D moieties. Ensemble and single- molecule measurements and theoretical calculations revealed that DB6 undergoes a photoabsorption process with two orthogonal transition dipole moments, whereas it fluoresces with a single transition dipole moment after one- or two-step ESB upon photoexcitation, depending on the environmental polarity. In nonpolar solvents and polymer films, one of the three D-pi-D sites becomes planar, and the excited state is localized on this moiety: a [D delta+-pi(delta-)-D delta+]* quadrupolar state is formed. In polar solvents, the symmetry is further broken within the planarized D-pi-D moiety, and the excited state is localized on one of the two D-pi sites; i.e., a D-[pi(delta-)-D delta+]* dipolar state is generated. Hence, DB6 can behave like a multichromophore with multiple emission sites in the molecule, which was demonstrated by stepwise photobleaching under photon antibunching conditions.

      DOI: 10.1021/acs.jpcb.1c04915

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    • Starburst-Shaped D-pi-A Chromophores Possessing a Hexaethynylbenzene Core for Dye-Sensitized Solar Cells 査読有り

      Masaaki Mitsui, Yushiro Nakagome, Yoshiki Niihori, Shota Inoue, Yutaka Fujiwara, Kenji Kobayashi

      ACS APPLIED MATERIALS & INTERFACES13 ( 30 ) 35739 - 35749   2021年8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  

      Two starburst-shaped organic chromophores, incorporating a hexaethynylbenzene core modified by five donor branches (D-branches) of (p-dioctylaminostyryl)benzene and one acceptor/anchoring branch (A-branch) of either carboxylic acid-terminated phenylethynylbenzene (SB-07) or cyanoacrylic acid-terminated diketopyrrolopyrrole (DPP)-thiophene (SB-08), were synthesized and applied to dye-sensitized solar cells (DSSCs). In these chromophores, the common donor moiety, five (p-dioctylaminostyryl)phenyl groups, exhibits excellent optical absorption in the visible region (molar absorption coefficient epsilon > 10(5) M-1 cm(-1) below 500 nm). The A-branch of SB-07 does not possess strong electron-accepting properties; however, the A-branch of SB-08, the DPP-thiophene moiety, serves as a strong electron acceptor site. Furthermore, the intramolecular charge-transfer (ICT) transition between the thiophene and DPP moieties extends the optical absorption range to the near-infrared region (similar to 800 nm). Optimized DSSC devices using SB-08 with coadsorption of chenodeoxycholic acid, in conjunction with iodide/triiodide-based electrolytes, exhibited incident photon-to-current conversion efficiency (IPCE) exceeding 70% in the 370-700 nm range and over 20% even at 800 nm, with a short-circuit photocurrent density (J(sc)) of 19.3 mA cm(-2) and a power conversion efficiency (PCE) of 6.4% under AM 1.5G illumination (100 mW cm(-2)). These results are considerably better than those of SB-07 (J(sc) = 7.0 mA cm(-2), PCE = 3.3%). The starburst-shaped architecture presented here can be used as a novel structural motif for metal-free organic sensitizers because it enables flexible modification of the multiple D-branches that enhance light-harvesting ability and the A-branch that serves as an excited electron transport pathway.

      DOI: 10.1021/acsami.1c08431

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    • Single Platinum Atom Doping to Silver Clusters Enables Near-Infrared-to-Blue Photon Upconversion 査読有り

      Yoshiki Niihori, Yuki Wada, Masaaki Mitsui

      ANGEWANDTE CHEMIE-INTERNATIONAL EDITION60 ( 6 ) 2822 - 2827   2021年2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:WILEY-V C H VERLAG GMBH  

      Photon upconversion (UC) from near-infrared (NIR) to visible has been realized using singlet-to-triplet absorption of sensitizers, which are currently limited to osmium complexes and semiconductor nanocrystals. Motivated by the atomically precise tunability of electronic structure and photophysical properties of noble metal clusters, which often possess absorption bands that extend into the NIR region, we investigated MAg24(SR)(18) (M=Ag, Pt; SR=2,4-dimethylbenzenethiolate) clusters as a new NIR-absorbing sensitizer for triplet-triplet annihilation UC. Combined with a blue light emitter, the NIR excitation (lambda(ex)=785 nm) of Ag-25(SR)(18) results in no UC emission, while PtAg24(SR)(18) exhibits strong UC emission. This enhancement is primarily due to a significant increase in the intersystem crossing quantum yield of the cluster associated with the spin-orbit coupling enhancement in the M@Ag-12 core.

      DOI: 10.1002/anie.202013725

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    • Synthesis and Properties of a Cyclohexa‐2,7‐anthrylene Ethynylene Derivative 査読有り

      Hironori Matsuki, Keisuke Okubo, Yuta Takaki, Yoshiki Niihori, Masaaki Mitsui, Eiichi Kayahara, Shigeru Yamago, Kenji Kobayashi

      Angewandte Chemie International Edition60 ( 2 ) 998 - 1003   2021年1月11日

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      担当区分:責任著者   掲載種別:研究論文(学術雑誌)   出版者・発行元:Wiley  

      DOI: 10.1002/anie.202012120

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      その他リンク: https://onlinelibrary.wiley.com/doi/full-xml/10.1002/anie.202012120

    • Quantification of Dyes Generating Photocurrent and/or Photoluminescence in Dye-Sensitized Solar Cells Using Laser Scanning Microscopy 招待有り 査読有り

      Masaaki Mitsui, Kyosuke Mori, Reina Kobayashi

      ENERGIES13 ( 8 )   2020年4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:MDPI  

      Photoconversion processes such as electron injection (photooxidation) and dye regeneration (reduction) in dye-sensitized solar cells (DSSCs) occur at considerably inhomogeneous semiconductor/dye/electrolyte interfaces, implying a very high heterogeneity of interfacial photoconversion kinetics. Herein, we present a temporally and spatially resolved investigation of DSSCs comprising a cover glass photoanode with a 100-nm thick TiO2 layer loaded with the metal-free organic dye sensitizer MK-2, which is performed by employing laser scanning microscopy (LSM) for the simultaneous measurement of the photocurrent (PC) and photoluminescence (PL) of DSSCs under short-circuit conditions. Analysis of PL decay curves and the excitation rate dependences of PC and PL obtained for local (or submicrometric) areas of the MK-2-DSSC allows disclosing and quantifying three types of dyes coexisting in the DSSCs: (i) a dye that only generates PC ("PC-dye," 75% of total dye molecules in the DSSC), (ii) a dye that generates both PC and PL ("PCPL-dye," 20%), and (iii) a dye that only generates PL ("PL-dye," 5%). Considering recent theoretical reports on cyanoacrylic dyes, we propose that the PC-dye and the PCPL-dye are covalently bound on a TiO2 surface with different adsorption modes (presumably bidentate and tridentate bridging configurations), whereas the PL-dye is noncovalently trapped within a mesoporous TiO2 film.

      DOI: 10.3390/en13081866

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    • Photophysical and Thermodynamic Properties of Ag-29(BDT)(12)(TPP)(x) (x=0-4) Clusters in Secondary Ligand Binding-Dissociation Equilibria Unraveled by Photoluminescence Analysis 査読有り

      Yoshiki Niihori, Naoya Takahashi, Masaaki Mitsui

      JOURNAL OF PHYSICAL CHEMISTRY C124 ( 10 ) 5880 - 5886   2020年3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:AMER CHEMICAL SOC  

      Despite the huge effort that has been devoted to the atomically precise synthesis and structural and physicochemical property characterization of ligand-protected noble metal clusters, quantitative knowledge of thermodynamic equilibrium in solutions of these clusters to date remains lacking. In this article, we report the determination of equilibrium constants for reversible binding-dissociation reactions of a secondary ligand, triphenylphosphine (TPP), in Ag-29(BDT)(12)(TPP)(x) (x = 0-4) clusters (BDT: 1,3-benzenedithiolate) achieved through photoluminescence (PL) analysis. Detailed analyses of TPP-concentration dependencies of PL decay times and PL quantum yields of the clusters under equilibrium allowed us to extract the PL lifetimes (tau(x)) and PL quantum yields (Phi(x)) of each composition (x = 0-4). Using these PL parameters, we reveal in this study how the relative abundances of each composition vary with the TPP concentration. From the simulation of these dependencies, we obtained the stability and equilibrium constants for each binding-dissociation reaction step in the sequential equilibrium. More importantly, the parent clusters, Ag-29(BDT)(12)(TPP)(4), in the solution underwent sequential loss of TPP ligands and became the binding-dissociation equilibria due to modest magnitudes of the equilibrium constant (K = 10(2)-10(4) M-1). Hence, our PL analysis approach is highly effective in determining the photophysical and thermodynamic parameters of inseparable clusters in dynamic equilibrium.

      DOI: 10.1021/acs.jpcc.9b11928

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    • Excited-State Symmetry Breaking of a Symmetrical Donor–π–Donor Quadrupolar Molecule at a Polymer/Glass Interface. 査読有り

      M. Mitsui, Y. Takakura, Y. Niihori, M. Nakamoto, Y. Fujiwara, K. Kobayashi

      J. Phys. Chem. C123 ( 23 ) 14564 - 14572   2019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)  

      DOI: 10.1021/acs.jpcc.9b03612

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    • Impacts of Environmental Rigidity on Photophysical Characteristics and Behaviors of a Quadrupolar Chromophore Revealed by Single-Molecule Fluorescence Spectroscopy 査読有り

      T. Mizukami, S. Inoue, H. Ohsawa, Y. Niihori, K. Kobayashi, M. Mitsui

      J. Phys. Chem. C122 ( 37 ) 21295 - 21307   2018年

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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)  

      DOI: 10.1021/acs.jpcc.8b03889

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    • Geometric and electronic properties of Si-atom doped Al clusters: robustness of binary superatoms against charging 査読有り

      Minoru Akutsu, Kiichirou Koyasu, Junko Atobe, Ken Miyajima, Masaaki Mitsui, Hironori Tsunoyama, Atsushi Nakajima

      PHYSICAL CHEMISTRY CHEMICAL PHYSICS19 ( 31 ) 20401 - 20411   2017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  

      The geometric and electronic properties of silicon-atom-doped aluminum clusters, AlnSim (n = 7-30, m = 0-2), were investigated experimentally. The size dependences of the ionization energy and electron affinity of AlnSim show that the stability of AlnSim is governed by the total number of valence electrons in the clusters, where Al and Si atoms behave as trivalent and tetravalent atoms, respectively. Together with theoretical calculations, it has been revealed that neutral Al10Si and Al12Si have a cage-like geometry with central Si atom encapsulation and closed electronic structures of superatomic orbitals (SAOs), and also that they both exhibit geometric robustness against reductive and oxidative changes as cage-like binary superatoms of Si@Al-10 and Si@Al-12. As well as the single-atom-doped binary superatoms, the effect of symmetry lowering was examined by doping a second Si atom toward the electron SAO closing of 2P SAO, forming Al11Si2. The corresponding anion and cation clusters keep their geometry of the neutral intact, and the ionization energy is low compared to others, showing that Al11Si2 is characterized to be, Si@Al11Si as an alkaline-like binary superatom. For Al21Si2, a face-sharing bi-icosahedral structure was identified to be the most stable as dimeric superatom clusters.

      DOI: 10.1039/c7cp03409a

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    • Methodology for Discriminating between Competitive Photophysical Processes in Photoblinking: Application to the Fluorescence Blinking of Single Dye Molecules Adsorbed on TiO2 査読有り

      Masaaki Mitsui, Aki Unno, Kyosuke Mori

      CHEMISTRY LETTERS46 ( 6 ) 866 - 869   2017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:CHEMICAL SOC JAPAN  

      The fluorescence blinking phenomenon, which is ubiquitous in single nano-objects, provides kinetic information concerning the underlying photophysics in these objects. However, considerable attention should be paid to the blinking analysis of these objects, especially, when they comprise multiple competitive processes. Here we report on a new protocol for discriminating between the competitive photophysical processes that cause fluorescence blinking. A robust statistical analysis was conducted by progressively changing a range of data to reveal the true blinking statistics caused by the electron-transfer dynamics at dye-TiO2 interfaces.

      DOI: 10.1246/cl.170127

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    • Electronic spectra and excited-state dynamics of acridine and its hydrated clusters 査読有り

      Colin Harthcock, Jie Zhang, Wei Kong, Masaaki Mitsui, Yasuhiro Ohshima

      JOURNAL OF CHEMICAL PHYSICS146 ( 13 ) 134311   2017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:AMER INST PHYSICS  

      We combine results from several different experiments to investigate the photophysics of acridine (Ac) and its hydrated clusters in the gas phase. Our findings are also compared with results from condensed phase studies. Similar to measurements of Ac dissolved in hydrocarbons, the lifetime of the first electronically excited state of isolated Ac in vacuum is too short for typical resonantly enhanced multiphoton ionization (REMPI) and laser induced fluorescence (LIF) experiments, hence no signal from REMPI and LIF can be attributed to monomeric Ac. Instead, sensitized phosphorescence emission spectroscopy is more successful in revealing the electronic states of Ac. Upon clustering with water, on the other hand, the lifetimes of the excited states are substantially increased to the nanosecond scale, and with two water molecules attached to Ac, the lifetime of the hydrated cluster is essentially the same as that of Ac in aqueous solutions. Detailed REMPI and ultraviolet-ultraviolet hole-burning experiments are then performed to reveal the structural information of the hydrated clusters. Although the formation of hydrogen bonds results in energy level reversal and energy separation between the first two excited states of Ac, its effect on the internal geometry of Ac is minimal, and all clusters with 1-3 water molecules demonstrate consistent intramolecular vibrational modes. Theoretical calculations reveal just one stable structure for each cluster under supersonic molecular beam conditions. Furthermore, different from mono-and di-water clusters, tri-water clusters consist of a linear chain of three water molecules attached to Ac. Consequently, the fragmentation pattern in the REMPI spectrum of tri-water clusters seems to be dominated by water trimer elimination, since the REMPI spectrum of Ac+ . W3 is largely reproduced in the Ac+ mass channel, but not in the Ac+ . W1 or Ac+ . W2 channel. Published by AIP Publishing.

      DOI: 10.1063/1.4979631

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    • Single-Molecule Fluorescence Spectroscopy of Perylene Diimide Dyes in a γ-Cyclodextrin Film: Manifestation of Photoinduced H-Atom Transfer via Higher Triplet (n, π*) Excited States 査読有り

      M. Mitsui, H. Fukui, R. Takahashi, Y. Takakura, T. Mizukami

      J. Phys. Chem. A121 ( 8 ) 1578 - 1587   2017年3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: 10.1021/acs.jpca.6b11353

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    • Synthesis and Self-Assembly of Cyclic 2,7-Anthrylene Ethynylene 1,3-Phenylene Ethynylene Trimer with a Planar Conformation 査読有り

      Yuta Takaki, Ryota Ozawa, Takashi Kajitani, Takanori Fukushima, Masaaki Mitsui, Kenji Kobayashi

      CHEMISTRY-A EUROPEAN JOURNAL22 ( 47 ) 16759 - 16763   2016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:WILEY-V C H VERLAG GMBH  

      Cyclic arylene ethynylene hexamer 1, composed of alternating 2,7-anthrylene ethynylene units and meta-phenylene ethynylene units, was synthesized. It shows C-3 symmetry and possesses a flat and rigid conformation with a large equilateral triangle-like cavity. Macrocycle 1 self-associates through pi-pi stacking interactions between the anthracene-containing macrocyclic aromatic cores with indefinite-association constant K-E=6980 M-1 in CDCl3 at 303 K. Macrocycle 1 also self-assembles into pi-stacked nanofibers in the drop-cast film.

      DOI: 10.1002/chem.201603627

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    • Effects of Supramolecular Encapsulation on Photophysics and Photostability of a 9,10-Bis(arylethynyl)anthracene-Based Chromophore Revealed by Single-Molecule Fluorescence Spectroscopy 査読有り

      Masaaki Mitsui, Koji Higashi, Yohei Hirumi, Kenji Kobayashi

      JOURNAL OF PHYSICAL CHEMISTRY A120 ( 42 ) 8317 - 8325   2016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:AMER CHEMICAL SOC  

      The effects of supramolecular encapsulation on the photophysics and photostability of a highly fluorescent dimeric derivative of 2,6-diacetox-y-9,10-bis(arylethynyl)anthracene (G2) were investigated by single-molecule fluorescence spectroscopy (SMFS). The fluorescence properties of free-G2 and its self-assembled boronic ester encapsulation complex, G2@(Cap)(2), were compared in solution and a glassy polymer film. The fluorescence spectral characteristics and theoretical calculations suggest that the environment affects the excited-state conformation and subsequent fluorescence emission of G2@(Cap)(2). In particular, in the liquid and polymer environments, G2@(Cap)(2) emits a fluorescence photon in the planar and twist conformation, respectively, whereas the fluorescence-emitting conformation of free-G2 is planar in both environments. The luminous conformation differences between free-G2 and G2@(Cap)(2) in polymer are reflected in the intersystem crossing (ISC) parameters (the ISC quantum yield and triplet lifetime), as determined by fluorescence autocorrelation analysis. The photobleaching yield revealed a 3-fold enhancement in the photostability of encapsulated G2 (relative to free-G2). Under the SMFS measurement conditions, the photostability of the encapsulation complex was independent of the guest's photostability and appeared to be dominated by the thermal stability of the Cap host molecule.

      DOI: 10.1021/acs.jpca.6b08734

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    • Understanding Photoinduced Charge Transfer Dynamics of Single Perylenediimide Dyes in a Polymer Matrix by Bin-Time Dependence of their Fluorescence Blinking Statistics 査読有り

      Masaaki Mitsui, Aki Unno, Syun Azechi

      JOURNAL OF PHYSICAL CHEMISTRY C120 ( 28 ) 15070 - 15081   2016年7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  

      Fluorescence on-off blinking of single perylenediimide (DMP-PDI) dyes embedded in a disordered matrix of poly(methyl methacrylate) (PMMA) was investigated by single-molecule fluorescence spectroscopy. In particular, we examined the bin-time dependencies of the complementary cumulative distribution functions (cCDF) of the on-time and off-time durations. It appears that intersystem crossing (ISC) within DMP-PDI competes with charge transfer between DMP-PDI and PMMA. The single-molecule and ensemble cCDFs of the on-time and off time durations (induced by charge transfer) were best described by Weibull functions and log-normal functions, respectively. The dispersive kinetics of the on-time duration were attributed to radical ion pair ISC from triplet charge separation ((CS)-C-3) state to the corresponding singlet ((CS)-C-1) state via charge hopping between charge trap sites in PMMA. This process should compete with triplet charge recombination ((CR)-C-3) which restores the triplet state. On-to-off switching occurs only when (CS)-C-3 -&gt; (CS)-C-1 ISC overcomes the (CR)-C-3 process. The resultant Weibull distribution (with A &lt; 1) reflects that the probability of charge hopping rapidly decreases with time. On the other hand, the off time log-normal kinetics of single-molecules are explained by a Gaussian distribution of activation energies for charge recombination (the so-called Albery model). A simulation study revealed that the ensemble off-time cCDF included power-law kinetics of charge hopping in the polymer matrix.

      DOI: 10.1021/acs.jpcc.6b04114

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    • Correlations between Photovoltaic Characteristics, Adsorption Number, and Regeneration Kinetics in Dye-Sensitized Solar Cells Revealed by Scanning Photocurrent Microscopy 査読有り

      Masaaki Mitsui, Yuya Kawano, Kyosuke Mori, Naoto Wakabayashi

      LANGMUIR31 ( 25 ) 7158 - 7165   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  

      Newly developed simultaneous scanning photocurrent and luminescence microscopy was applied to ruthenium-based dye-sensitized solar cells (DSCs) comprising a cover glass photoanode with a 100 nm thick TiO2 layer. Using this, we have investigated the lateral variations of several parameters of these DSCs under short-circuit conditions. Simultaneous measurement of photocurrent and luminescence images for the same area of the DSC demonstrated submicrometric lateral resolution of our photo current microscopy, which is approximately 10 times better than the resolution of photo current microscopy used in past studies. The photovoltaic parameters, such as short-circuit current density, open-circuit voltage, and charge-collection efficiency, were thus evaluated for local (or submicrometric) regions of the DSCs. Furthermore, the photocurrent saturation behavior of the DSCs was examined as a function of the excitation rate and analyzed on the basis of a three-state kinetic model. This protocol allowed for quantification of the dye-adsorption number and dye-regeneration rate constant for any local area of the DSCs. Consequently, the correlations between the dye adsorption number, photovoltaic parameters, and regeneration rate constant, which are difficult to address through examination of the entire cell, were revealed by the "zoom-in" approach utilizing this high-resolution photocurrent microscopy.

      DOI: 10.1021/acs.langmuir.5b01581

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    • Formation and Electronic Structures of Organoeuropium Sandwich Nanowires 査読有り

      Natsuki Hosoya, Ryuta Takegami, Jun-ichi Suzumura, Keizo Yada, Ken Miyajima, Masaaki Mitsui, Mark B. Knickelbein, Satoshi Yabushita, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A118 ( 37 ) 8298 - 8308   2014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)   出版者・発行元:AMER CHEMICAL SOC  

      Organoeuropium sandwich clusters, comprising europium (Eu) and 1,3,5,7-cyclooctatetraene (COT) (Eu-n(COT)(m)), were produced in the gas phase using a laser vaporization synthesis method. Photoionization mass spectra revealed an exclusive Eu-n(COT)(m) formation with three compositions: m = n + 1, m = n, and m = n - 1, which, we propose, correspond to full-sandwich, half-sandwich, and inverted-sandwich structures, respectively. The charge distributions, metal-ligand bonding characteristics, and electronic structures of the clusters were comprehensively investigated by photoionization measurements of Eu-n(COT)(m) neutrals and by photoelectron spectroscopy of Eu-n(COT)(m)(-) and isoelectronic Ba-n(COT)(m)(-) anions. The results confirmed that (1) highly ionic metal-ligand bonding is formed between Eu2+ and COT2- within the sandwich structure (at the termini, ionic forms are Eu+ and COT-) and (2) size dependence of orbital energy can be explained by the Coulombic interaction of simple point charge models between the detaching electrons and dipoles/quadrupoles. When the terminus of the sandwich clusters is Eu2+, COT2-, or Eu, the orbital energy of the electron detachment channel at the opposite terminus strongly depends on the cluster size. In this case, the molecular stack behaves as a one-dimensionally aligned dipole; otherwise, it behaves as a quadrupole, and the relationship between cluster size and electron detachment energy is much weaker. The study also reports on the 4f orbital energy in Eu ions and the formation mechanism of organoeuropium sandwich nanowires up to 12 nm in length. The nanowires are formed by successive charge transfer at the terminal part, Eu+ and COT-, which reduces the ionization energy and increases the electron affinity, respectively.

      DOI: 10.1021/jp5011007

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    • Encapsulation with the Protrusion of Cruciform 9,10Bis( arylethynyl) anthracene Derivatives in a Self- Assembled Boronic Ester Cavitand Capsule: Photochemical and Photophysical Properties 査読有り

      Yohei Hirumi, Kento Tamaki, Tomotaka Namikawa, Kenji Kamada, Masaaki Mitsui, Kengo Suzuki, Kenji Kobayashi

      CHEMISTRY-AN ASIAN JOURNAL9 ( 5 ) 1282 - 1290   2014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:WILEY-V C H VERLAG GMBH  

      The self-assembled boronic ester cavitand capsule 3 quantitatively and tightly encapsulates 2,6-diacetoxy-9,10-bis(arylethynyl)anthracene derivatives 4a-4c as highly fluorescent cruciform guests to form complexes 4a@3, 4b@3, and 4c@(3)(2). The structural features of capsule 3, which possesses two polar bowl-shaped aromatic cavity ends and four large equatorial windows connected by dynamic boronic ester bonds, made it possible to encapsulate cruciform 4 with protection of the reactive anthracene core inside the capsule and with two protruding arylethynyl groups, the -conjugated arms of compound 4, through two of the equatorial windows of the capsule. Thus, complexes 4a@3, 4b@3, and 4c@(3)(2) show greater resistance to photochemical reactions in solution and fluorescence quenching in the powder state compared to free guests 4. In addition to the improved photostability, restriction of the free rotation of the arylethynyl groups of guests 4 upon encapsulation results in sharpening of the UV/Vis absorption peaks with a red-shift and a significant increase in some of the two-photon-absorption peaks of complexes 4a@3, 4b@3, and 4c@(3)(2) compared with free guests 4.

      DOI: 10.1002/asia.201400042

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    • Enhanced photostability of an anthracene-based dye due to supramolecular encapsulation: a new type of photostable fluorophore for single-molecule study 査読有り

      Masaaki Mitsui, Koji Higashi, Ryoya Takahashi, Yohei Hirumi, Kenji Kobayashi

      PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES13 ( 8 ) 1130 - 1136   2014年

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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:ROYAL SOC CHEMISTRY  

      For single-molecule fluorescence studies, highly photostable fluorophores are absolutely imperative, because photo-induced degradation (i.e., photobleaching) limits the observation time of individual molecules. Herein, the photophysics and photostability of a highly fluorescent 9,10-bis(phenylethynyl) anthracene derivative (G) and its self-assembled boronic ester encapsulation complex (G@Cap) embedded in a glassy polymer matrix are investigated by single-molecule fluorescence spectroscopy (SMFS). The heterogeneity of the fluorescence emission wavelength and triplet blinking kinetics of the guest G are significantly decreased by supramolecular encapsulation due to conformational restriction and reduced heterogeneity in the local environment. A nearly 10-fold increase in the photostability of G due to encapsulation is quantitatively confirmed by evaluating the photobleaching yields of G and G@Cap. In addition, it is found that the G@Cap is &gt; 30-fold more photostable than rhodamine 6G, a widely used fluorescent dye in single-molecule studies. These results demonstrate that the G@Cap can serve as a very bright, long-lasting fluorescent probe for single-molecule studies.

      DOI: 10.1039/c4pp00065j

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    • Electronic energy transfer in tetracene-doped p-terphenyl nanoparticles: Extraordinarily high fluorescence enhancement and quenching efficiency 査読有り

      Masaaki Mitsui, Yuya Kawano

      CHEMICAL PHYSICS419   30 - 36   2013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:ELSEVIER SCIENCE BV  

      A series of tetracene (Tc)-doped p-terphenyl (pTP) nanoparticles (Tc/pTP-NPs) were produced at various doping ratios by reprecipitation in water. The Tc/pTP-NPs are disk-like with a mean diameter of 75 nm and height of 7 nm, which were determined by scanning electron microscopy and atomic force microscopy, and exhibited electronic delocalization through H-type aggregation of the pTP molecules. Electronic energy transfer in the Tc/pTP-NPs was examined using steady-state and time-resolved fluorescence spectroscopy and fluorescence anisotropy experiments: pTP-NPs serve as an excellent light-harvesting nano-matrix with a large absorption coefficient that exceeds 10(9) M (1) cm (1). Furthermore, Stern-Volmer analysis of the donor emission was performed by changing the dopant concentration; this showed that a single Tc acceptor quenched more than 10(4) pTP donors. Comparison of the experimental and theoretical energy transfer efficiencies indicated that the efficient energy transfer can be attributed to two-dimensional exciton diffusion in the host nanoparticles. (C) 2013 Elsevier B.V. All rights reserved.

      DOI: 10.1016/j.chemphys.2013.01.004

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    • Photophysics and photostability of 9,10-bis(phenylethynyl)anthracene revealed by single-molecule spectroscopy 査読有り

      Masaaki Mitsui, Yuya Kawano, Ryoya Takahashi, Hiroki Fukui

      RSC ADVANCES2 ( 26 ) 9921 - 9931   2012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:ROYAL SOC CHEMISTRY  

      The photophysics and photostability of 9,10-bis(phenylethynyl) anthracene (BPEA) diluted in a 40-nm-thick Zeonex polymer film have been investigated by single-molecule spectroscopy (SMS). The single-molecule detection of BPEA was verified by recording fluorescence intensity trajectories, fluorescence lifetimes, and fluorescence spectra. The intensity trajectories showed frequent on/off blinking and one-step photobleaching behaviors. The observed blinking was attributed to the temporary occupation of the excited triplet state T-1 via intersystem crossing (ISC). Assuming a three-state model (e.g., S-0, S-1, and T-1), the distributions of triplet lifetime and S-1 -&gt; T-1 ISC quantum yield of BPEA were both derived from the analyses of the blinking statistics and the intensity autocorrelation. We found extremely low ISC yields (on the order of 10(-5)-10(-4)), which were theoretically rationalized by the large energy gap between B-3(2u) and S-1(B-1(1u))/T-1(B-3(1u)) states. SMS measurements were also conducted under both air and Ar atmospheres in order to gain insight into the influence of oxygen on photobleaching. The results reveal that, although the presence of oxygen considerably degraded the photostability of BPEA, under deoxygenated conditions, BPEA delivers more than 10(7) photons before photobleaching and possesses an appreciably low photobleaching yield of 10(-9)-10(-8). This study shows that BPEA has a relatively high degree of photostability at room temperature and can serve as a useful green fluorescent probe for SMS studies.

      DOI: 10.1039/c2ra21100a

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    • 温度可変単一分子蛍光分光測定のための簡易試料基板ホルダーの開発 査読有り

      三井正明, 河野祐也, 高橋良弥, 福井洋樹

      分光研究60 ( 4 ) 133 - 134   2011年

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      担当区分:筆頭著者, 責任著者   記述言語:日本語   掲載種別:研究論文(学術雑誌)   出版者・発行元:日本分光学会  

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    • Characterization of alkyl monolayer covalently bonded to Si(111) and soft-landing of vanadium-benzene sandwich clusters onto the alkyl monolayer substrate 査読有り

      T. Matsumoto, S. Nagaoka, K. Ikemoto, M. Mitsui, M. Ara, H. Tada, A. Nakajima

      EUROPEAN PHYSICAL JOURNAL D52 ( 1-3 ) 99 - 102   2009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:SPRINGER  

      A hexadecyl monolayer covalently attached to Si(111) surfaces (C(16)-Si(111)) was prepared at; 200 degrees C from 1-hexadecene. Formation of the monolayer was characterized by water contact all-le measurement, attenuated total reflection infrared (ATR-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Gas phase synthesized vanadium (V)-benzene (Bz) 1:2 (VBz(2)) sandwich Clusters were size-selectively deposited onto the C(16)-Si(111) substrate thus prepared and an oxidized Si substrate. Investigation of the resultant. clusters, was implemented by thermal desorption spectroscopy (TDS). About 30 K increase ill threshold desorption temperature of the landed clusters was observed oil going from the oxidized Si to the C(16)-Si(111) substrate, a, result indicating that. the clusters are more strongly bound to the C(16)-Si(111) than to the oxidized Si. This result was explained by the penetration of the landed clusters into the hexadecyl monolayer.

      DOI: 10.1140/epjd/e2009-00069-9

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    • An atomic force microscope study of vanadium-benzene sandwich clusters soft-landed on self-assembled monolayers 査読有り

      S. Nagaoka, K. Ikemoto, K. Fujio, K. Hiehata, A. Sasahara, M. Mitsui, H. Onishi, A. Nakajima

      EUROPEAN PHYSICAL JOURNAL D52 ( 1-3 ) 103 - 106   2009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:SPRINGER  

      Multiple-decker vanadium-benzene sandwich clusters V(n)(beuzeue)(n+1) produced by a laser-vaporization synthesis method were soft-landed onto self-assembled monolayers of alkanethiol (C(18) H-SAM) and fluorinated alkanethiol (C(10)F-SAM) at 200 K. Noncontact atomic force microscopy has been used to examine the resulting adsorption states Of the Clusters lauded on the SAMs at room temperature. For each SAM substrate, the aggregates of the deposited clusters were observed at the vacancy islands and near the steps of the SAM surface. The result indicates that., at room temperature, the clusters landed Oil the SAM substrate thermally diffuse on the surface to form columnar-shape islands around the defect sites, of the SAM surface.

      DOI: 10.1140/epjd/e2009-00068-x

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    • Soft-Landing Experiments of Cr(benzene)(2) Sandwich Complexes onto a Carboxyl-Terminated Self-Assembled Monolayer Matrix 査読有り

      Kaori Ikemoto, Shuhei Nagaoka, Takeshi Matsumoto, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY C113 ( 11 ) 4476 - 4482   2009年3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  

      Gas-phase synthesized Cr(benzene)(2) sandwich complexes were soft-landed onto a carboxyl-terminated self-assembled monolayer (C15COOH-SAM) on a gold substrate at hyperthermal collision energy (5-20 eV). The deposition process and adsorption properties of the soft-landed complexes were investigated by means of infrared reflection absorption spectroscopy (IRAS) and temperature programmed desorption (TPD) measurements. With the soft-landing, the Cr(benzene)(2) complexes are adsorbed at the SAM surface while keeping their native sandwich structure intact even after the hyperthermal collision event. Moreover, the complexes tend to orient their molecular axes reasonably or comparatively close to the surface normal direction to the SAM surface. This orientation might arise from chemical interactions between the benzene ring in the sandwich complexes and carboxyl groups on the SAM surface. An Arrhenius analysis of the TPD spectra reveals the desorption activation energy of soft-landed complexes as 133 +/- 10 kJ/mol, a value which is comparable to typical adsorption heat of chemisorptions. Chemical interactions between the Cr(benzene)(2) complexes and carboxyl groups would provide firm trapping of the complexes at the SAM surface, preventing the supported complexes from being desorbed until near room temperature.

      DOI: 10.1021/jp807137p

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    • Soft-landing isolation of gas-phase-synthesized transition metal-benzene complexes into a fluorinated self-assembled monolayer matrix 査読有り

      Shuhei Nagaoka, Kaori Ikemoto, Takeshi Matsumoto, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY C112 ( 40 ) 15824 - 15831   2008年10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  

      Gas-phase-synthesized chromium-benzene 1:2 sandwich cation complexes [Cr+(benzene)(2)] were soft-landed on a self-assembled monolayer (SAM) of fluorinated alkanethiol (C10F-SAM) at a hyperthermal collision energy of similar to 20 eV. The adsorption properties and thermal stability of the soft-landed complexes were studied with infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). The landed complexes were neutralized due to charge transfer from the SAM substrate, but their native sandwich structure remained intact. The hyperthermal collision event resulted in the penetration of the incoming complexes into the C10F-SAM matrix. The embedded complexes then tended to orient their molecular axes approximately along the surface normal. This orientational preference is measurably different from that of complexes isolated in alkanethiol SAM matrices, a discrepancy that might be caused by a repulsive interaction between the pi cloud of the capping benzene rings of the complex and the side-chain CF2 groups of the fluorocarbon chains in the C10F-SAM matrix. The thermal desorption study showed that the complexes supported inside the C10F-SAM could resist thermal desorption until the high-temperature region of similar to 320 K, a persistence revealing a large desorption activation energy (similar to 190 kJ/mol).

      DOI: 10.1021/jp8055784

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    • Mass spectroscopic study of metal-rich K2-5(KI)(n)(+) nanoclusters 査読有り

      S. H. Huh, H. S. Jeong, K. Koyasu, K. Miyajima, M. Mitsui, A. Nakajima

      JOURNAL OF MOLECULAR STRUCTURE886 ( 1-3 ) 39 - 42   2008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:ELSEVIER SCIENCE BV  

      Metal-rich K1-5(KI)(n)(+) (n similar to 27) clusters were produced by the supersonic cooling expansion of laser-induced KI plasma. The obtained mass spectroscopic peaks show the unique magic numbers at n = 9, 13, and 22 for K-1(KI)(n); n = 8, 12, and 21 for K-2(KI)(n); n = 8, 12, 16, and 21 for K-3(KI)(n); n 7, 9, 11, and 13 for K-4(KI)(n); and n = 12 and 21 for K-5(KI)(n). These magic numbers are fairly different from those of other reported metal-rich Na1-9(NaF)(n)(+) and Cs1-5(CsI)(n)(+) clusters. It is interesting to note that K-2.3,K-5(KI)(n)(+) clusters have the same magic numbers at n = 12 and 21 and possess structures that are closely related to the 3 x 3 x 3 and 3 x 3 x 5 cubic structures with the excess electron at the side anion vacancy or the center anion vacancy. (C) 2007 Elsevier B.V. All rights reserved.

      DOI: 10.1016/j.molstruc.2007.02.011

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    • Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions: The effect of molecular shape on molecular assembly and ion core character 査読有り

      Masaaki Mitsui, Naoto Ando, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A112 ( 25 ) 5628 - 5635   2008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)   出版者・発行元:AMER CHEMICAL SOC  

      Mass spectrometry and photoelectron spectroscopy of o-, m-, and p-terphenyl cluster anions, (o-TP)(n)(-) (n = 2-100), (m-TP)(n)(-) (n = 2-100), and (p-TP)(n)(-) (n = 1-100), respectively, are conducted to investigate the effect of molecular shape on the molecular aggregation form and the resultant ion core character of the clusters. For (o-TP)(n)(-) and (m-TP)(n)(-), neither magic numbers nor discernible isomers are observed throughout the size range. Furthermore, their vertical detachment energies (VDEs) increase up to large n and depend linearly on n(-1/3), implying that they possess a three-dimensional (3D), highly reorganized structure encompassing a monomeric anion core. For (p-TP)(n)(-), in contrast, prominent magic numbers of n = 5, 7, 10, 12, and 14 are observed, and the VDEs show pronounced irregular shifts below n = 10, while they remain constant above n = 14 (isomer A). These results can be rationalized with two-dimensional (2D) orderings of p-TP molecules and different types of 2D shell closure at n = 7 and 14, the monomeric and multimeric anion core, respectively. Above n = 16, the new feature (isomer B) starts to appear at the higher binding side of isomer A, and it becomes dominant with n, while isomer A gradually disappears for larger sizes. In contrast to isomer A, the VDEs of isomer B continuously increase with the cluster size. This characteristic size evolution suggests that the transition to modified 2D aggregation forms from 2D ones occurs at around n = 20.

      DOI: 10.1021/jp801159n

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    • Thermal and hyperthermal collision-energy depositions of transition metal-benzene sandwich complexes onto a self-assembled n-octadecanethiol monolayer 査読有り

      Shuhei Nagaoka, Kaori Ikemoto, Takeshi Matsumoto, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY C112 ( 17 ) 6891 - 6899   2008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:AMER CHEMICAL SOC  

      Gas-phase synthesized transition metal-benzene sandwich complexes of M(benzene)2 (M = Ti, V, and Cr) are soft-landed onto a self-assembled monolayer of n-octadecanethiol (C-18-SAM) at a collision energy of 10-20 eV. The resulting adsorption states and thermal desorption kinetics of the soft-landed complexes are studied with infrared reflection absorption spectroscopy and temperature-programmed desorption. The complexes keep their native sandwich structure intact on the SAM substrate even after the "hyperthermal" deposition event. The soft-landed complexes are oriented with their molecular axes largely tilted off the surface normal of the SAM substrate and exhibit unusually large desorption activation energies (E-d = similar to 130 kJ/mol). For comparison, thermal deposition (similar to 25 meV) of Cr(benzene)2 vapor onto the C-18-SAM, carried out using a physical vapor deposition technique, showed that the complexes are weakly physisorbed (E-d = similar to 70 kJ/mol) on the SAM with a random orientation. Only a hyperthermal collision event allows the incident complexes to penetrate into the SAM matrix. The desorption of the embedded complexes in the SAM is then suppressed to around room temperature and may be associated with the crystal-rotator phase transitions of the SAM matrix.

      DOI: 10.1021/jp711695s

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    • Photoelectron spectroscopy of cluster anions of naphthalene and related aromatic hydrocarbons 査読有り

      Naoto Ando, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF CHEMICAL PHYSICS128 ( 15 ) 154318-1 - 154318-8   2008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:AMER INST PHYSICS  

      The electronic structures and structural morphologies of naphthalene cluster anions, (naphthalene)(n)(-) (n=3-150), and its related aromatic cluster anions, (acenaphthene)(n)(-) (n=4-100) and (azulene)(n)(-) (n=1-100), are studied using anion photoelectron spectroscopy. For (naphthalene)(n)(-) clusters, two isomers coexist over a wide size range: isomers I and II-1 (28 &lt;= n &lt;= 60) or isomers I and II-2 (n &gt;= similar to 60). Their contributions to the photoelectron spectra can be separated using an anion beam hole-burning technique. In contrast, such an isomer coexistence is not observed for (acenaphthene)(n)(-) and (azulene)(n)(-) clusters, where isomer I is exclusively formed throughout the whole size range. The vertical detachment energies (VDEs) of isomer I (7 &lt;= n &lt;= 100) in all the anionic clusters depend linearly on n(-1/3) and their size-dependent energetics are quite similar to one another. On the other hand, the VDEs of isomers II-1 and II-2 produced in (naphthalene)(n)(-) clusters with n &gt;= similar to 30 remain constant at 0.84 and 0.99 eV, respectively, 0.4-0.6 eV lower than those of isomer I. Based upon the ion source condition dependence and the hole-burning photoelectron spectra experiments for each isomer, the energetics and characteristics of isomers I, II-1, and II-2 are discussed: isomer I is an internalized anion state accompanied by a large change in its cluster geometry after electron attachment, while isomers II-1 and II-2 are crystal-like states with little structural relaxation. The nonappearance of isomers II-1 and II-2 for (acenaphthene)(n)(-) and (azulene)(n)(-) and a comparison with other aromatic cluster anions indicate that a highly anisotropic and symmetric pi-conjugated molecular framework, such as found in the linear oligoacenes, is an essential factor for the formation of the crystal-like ordered forms (isomers II-1 and II-2). On the other hand, lowering the molecular symmetry makes their production unfavorable. (c) 2008 American Institute of Physics.

      DOI: 10.1063/1.2903473

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    • Comprehensive photoelectron spectroscopic study of anionic clusters of anthracene and its alkyl derivatives: Electronic structures bridging molecules to bulk 査読有り

      Naoto Ando, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF CHEMICAL PHYSICS127 ( 23 ) 234305-13   2007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 INST PHYSICS  

      The evolution of the electronic structure of molecular aggregates is investigated using anion photoelectron (PE) spectroscopy for anionic clusters of anthracene (Ac) and its alkyl derivatives: 1-methylanthracene (1MA), 2-methylanthracene (2MA), 9-methylanthracene (9MA), 9,10-dimethylanthracene (DMA), and 2-tert-butylanthracene (2TBA). For their monomer anions (n=1), electron affinities are confined to the range from 0.47 to 0.59 eV and are well reproduced by density functional theory calculations, showing the isoelectronic character of these molecules. For cluster anions (n=2-100) of Ac and 2MA, two types of isomers I and II coexist over a wide size range: isomers I and II-1 (4 &lt;= n &lt; 30) or isomers I and II-2 (n &gt;=similar to 40 for Ac and n &gt;=similar to 55 for 2MA). However, for the other alkyl-substituted Ac cluster anions (i.e., 1MA, 9MA, DMA, and 2TBA), only isomer I is exclusively formed, and neither isomer II-1 nor II-2 is observed. The vertical detachment energies (VDEs) of isomer I in all the anionic clusters depend almost linearly on n(-1/3). In contrast, the VDEs of isomers II-1 (n &gt;= 14) and II-2 (n=40-100), appeared only in Ac and 2MA cluster anions, remain constant with n and are similar to 0.5 eV lower than those of isomer I. The PE spectra revealed the characteristics of each isomer: isomer I possesses a monomeric anion core that is gradually embedded into the interior of the cluster with increasing n. On the other hand, isomers II-1 and II-2 possess a multimeric (perhaps tetrameric) anion core, but they differ in the number of layers from which they are made up; monolayer (isomer II-1) and multilayers (isomer II-2) of a two-dimensionally ordered, finite herringbone-type structure, in which electron attachment produces only little geometrical rearrangement. Moreover, the agreement of the constant VDEs of isomer II-2 with the bulk data demonstrates the largely localized nature of the electronic polarization around the excess charge in a crystal-like environment, where about 50 molecules provide a charge stabilization energy comparable to the bulk.

      DOI: 10.1063/1.2805185

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    • Mass spectrometry and photoelectron spectroscopy of tetracene cluster anions, (Tetracene)(n)(-) (n=1-100): Evidence for the highly localized nature of polarization in a cluster analogue of oligoacene crystals 査読有り

      Masaaki Mitsui, Naoto Ando, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A111 ( 39 ) 9644 - 9648   2007年10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  

      Photoelectron spectroscopy of tetracene cluster anions, (tetracene), (n = 1 - 100), reveals the coexistence of two types of isomers, designated as isomers I and II-1 (n = 10-50) or isomers I and II-2 (n &gt; 60), in a wide size range. The vertical detachment energies (VDEs) of isomer I increase persistently due to polarization and structural relaxation effects, where a monomeric anion core is encompassed with geometrically reorganized neutral molecules. Conversely, a characteristic ion distribution in the mass spectrum of (tetracene),, ensues from the two-dimensional (2D) herringbone-type ordering of isomer II-1, whose VDEs remain constant at 1.80 eV for n &gt;= 14. Also, isomer II-2, presumably adopting multilayered structural motifs, exhibits invariable VDEs of 2.0 eV, a manifestation of significant charge screening effects in these isomers. The invariable nature of the VDEs of isomers II-1 and II-2 unambiguously demonstrates a largely localized nature of polarization induced by the excess charge residing in microscopic crystal-like environments. Surprisingly, only 14 tetracene molecules within a 2D herringbone-type layer including an excess charge can provide the charge stabilization energy corresponding to similar to 80% of that of the crystal, and the rest of the energy is provided by polarization of neutral molecules in adjacent layers.

      DOI: 10.1021/jp076134h

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    • Fabrication and characterization of a granular film consisting of size-selected silver nanoparticles: application to a SERS substrate 査読有り

      S. Kawabata, N. Ishikawa, M. Mitsui, A. Nakajima

      EUROPEAN PHYSICAL JOURNAL D43 ( 1-3 ) 155 - 158   2007年7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:SPRINGER  

      Uniform-sized silver nanoparticles with average diameter of 13.7 nm have been prepared in the gas-phase by combining a pulsed laser ablation method with a low pressure-differential mobility analyzer (LP-DMA). By depositing the silver nanoparticles onto a silicon substrate, a granular film consisting of size-selected silver nanoparticles has been fabricated and its morphology and electronic properties have been examined using transmission electron microscopy (TEM) and UV-visible absorption spectroscopy. This granular silver film serves as a highly active substrate for surface-enhanced Raman scattering (SERS).

      DOI: 10.1140/epjd/e2007-00064-2

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    • Formation of large molecular cluster anions and elucidation of their electronic structures 招待有り 査読有り

      Masaaki Mitsui, Atsushi Nakajima

      BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN80 ( 6 ) 1058 - 1074   2007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)   出版者・発行元:CHEMICAL SOC JAPAN  

      The present account describes our efforts to understand the microscopic aspects of condense phase phenomena, such as ion solvation in molecular liquids and charge carrier localization in molecular solids, by viewing finite-size molecular clusters as their embryonic forms. In this effort, we efficiently prepared supersonically cooled, isolated molecular cluster anions with up to more than 100 constituent molecules and size-selectively investigated their electronic structures using anion photoelectron spectroscopy. Large anionic clusters of two different types of organic molecule; acetonitrile and naphthalene reported as examples of the noteworthy results obtained in our studies. In these two systems, we found that energetically close anionic isomers coexist over a broad range in size, and their contribution in the photoelectron spectra could be separated using anion beam hole-burning technique. A detailed inspection into the electronic states and size-dependent energetics of each isomer has enabled us to establish a link from the large finite cluster to the infinite bulk system.

      DOI: 10.1246/bcsj.80.1058

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    • Soft-landing isolation of multidecker V-2(benzene)(3) complexes in an organic monolayer matrix: An infrared spectroscopy and thermal desorption study 査読有り

      Shuhei Nagaoka, Takeshi Matsumoto, Kaori Ikemoto, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF THE AMERICAN CHEMICAL SOCIETY129 ( 6 ) 1528 - +   2007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  

      Gas-phase synthesized multidecker V-2(benzene)(3) sandwich complexes were soft-landed onto a self-assembled monolayer of an n-octadecanethiol (C-18-SAM). The infrared absorption spectrum of this complex supported on the C-18-SAM was obtained by infrared reflection absorption spectroscopy (IRAS). The vibrational assignment of the IRAS spectrum for the V-2(benzene)(3) sandwich was based on a harmonic frequency analysis that employed density functional theory. The close similarity between the experimental and calculated results for the IR absorption frequencies demonstrates that the V-2(benzene)(3) complexes have a multidecker sandwich structure on the SAM substrate. Moreover, our thermal desorption study established that the sandwich complexes can be isolated on the SAM substrate up to a high temperature of similar to 350 K.

      DOI: 10.1021/ja068442j

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    • Electronic properties of si and ge atoms doped in clusters: InnSim and InnGem 査読有り

      Minoru Akutsu, Kiichirou Koyasu, Junko Atobe, Ken Miyajima, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A111 ( 4 ) 573 - 577   2007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  

      Electronic properties of silicon and germanium atom doped indium clusters, InnSim and InnGem, were investigated by photoionization spectroscopy of the neutrals and photoelectron spectroscopy of the anions. Size dependence of ionization energy and electron affinity for InnSi1 and InnGe1 exhibit pronounced even-odd alternation at cluster sizes of n = 10-16, as compared to those for pure In-n clusters. This result shows that symmetry lowering with the doped atom of Si or Ge results in undegeneration of electronic states in the 1d shell formed by monovalent In atoms.

      DOI: 10.1021/jp065921w

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    • π電子系分子クラスターの電子状態と集合構造の協同性 招待有り 査読有り

      三井正明, 中嶋敦

      Molecular Science1   A0007   2007年

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      記述言語:日本語   掲載種別:研究論文(学術雑誌)  

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    • Electronic and geometric stabilities of clusters with transition metal encapsulated by silicon 査読有り

      Kiichirou Koyasu, Junko Atobe, Minoru Akutsu, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A111 ( 1 ) 42 - 49   2007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  

      Silicon clusters mixed with a transition metal atom, MSin, were generated by a double-laser vaporization method, and the electronic and geometric stabilities for the resulting clusters with transition metal encapsulated by silicon were examined experimentally. By means of a systematic doping with transition metal atoms of groups 3, 4, and 5 (M = Sc, Y, Lu, Ti, Zr, Hf, V, Nb, and Ta), followed by changes of charge states, we explored the use of an electronic closing of a silicon caged cluster and variations in its cavity size to facilitate metal-atom encapsulation. Results obtained by mass spectrometry, anion photoelectron spectroscopy, and adsorption reactivity toward H2O show that the neutral cluster doped with a group 4 atom features an electronic and a geometric closing at n = 16. The MSi16 cluster with a group 4 atom undergoes an electronic change in (i) the number of valence electrons when the metal atom is substituted by the neighboring metals with a group 3 or 5 atom and in (ii) atomic radii with the substitution of the same group elements of Zr and Hf. The reactivity of a halogen atom with the MSi16 clusters reveals that VSi16F forms a superatom complex with ionic bonding.

      DOI: 10.1021/jp066757f

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    • Electronic and geometric stabilities of clusters with transition metal encapsulated by silicon 査読有り

      Kiichirou Koyasu, Junko Atobe, Minoru Akutsu, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A111 ( 1 ) 42 - 49   2007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  

      Silicon clusters mixed with a transition metal atom, MSin, were generated by a double-laser vaporization method, and the electronic and geometric stabilities for the resulting clusters with transition metal encapsulated by silicon were examined experimentally. By means of a systematic doping with transition metal atoms of groups 3, 4, and 5 (M = Sc, Y, Lu, Ti, Zr, Hf, V, Nb, and Ta), followed by changes of charge states, we explored the use of an electronic closing of a silicon caged cluster and variations in its cavity size to facilitate metal-atom encapsulation. Results obtained by mass spectrometry, anion photoelectron spectroscopy, and adsorption reactivity toward H2O show that the neutral cluster doped with a group 4 atom features an electronic and a geometric closing at n = 16. The MSi16 cluster with a group 4 atom undergoes an electronic change in (i) the number of valence electrons when the metal atom is substituted by the neighboring metals with a group 3 or 5 atom and in (ii) atomic radii with the substitution of the same group elements of Zr and Hf. The reactivity of a halogen atom with the MSi16 clusters reveals that VSi16F forms a superatom complex with ionic bonding.

      DOI: 10.1021/jp066757f

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    • Experimental and theoretical characterization of aluminum-based binary superatoms of Al12X and their cluster salts 査読有り

      Minoru Akutsu, Kiichirou Koyasu, Junko Atobe, Natsuki Hosoya, Ken Miyajima, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A110 ( 44 ) 12073 - 12076   2006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  

      The geometric and electronic structures of aluminum binary clusters, AlnX (X) Si and P), have been investigated, using mass spectrometry, anion photoelectron spectroscopy, photoionization spectroscopy, and theoretical calculations. Both experimental and theoretical results show that Al12Si has a high ionization energy and low electron affinity and Al12P has a low ionization energy, both with the icosahedral structure having a central Si or P atom, revealing that Al12Si and Al12P exhibit rare- gas- like and alkali superatoms, respectively. Experiments confirmed the possibility that the change in the total number of valence electrons on substitution could produce ionically bound binary superatom complexes, the binary cluster salts Al12P+F- and Al12B-Cs+.

      DOI: 10.1021/jp065161p

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    • Room-temperature isolation of V(benzene)(2) sandwich clusters via soft-landing into n-alkanethiol self-assembled monolayers 査読有り

      Shuhei Nagaoka, Takeshi Matsumoto, Eiji Okada, Masaaki Mitsui, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY B110 ( 32 ) 16008 - 16017   2006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:AMER CHEMICAL SOC  

      The adsorption state and thermal stability of V( benzene)(2) sandwich clusters soft-landed onto a self- assembled monolayer of different chain-length n-alkanethiols (C-n-SAM, n) 8, 12, 16, 18, and 22) were studied by means of infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). The IRAS measurement confirmed that V(benzene)(2) clusters are molecularly adsorbed and maintain a sandwich structure on all of the SAM substrates. In addition, the clusters supported on the SAM substrates are oriented with their molecular axes tilted 70-80 off the surface normal. An Arrhenius analysis of the TPD spectra reveals that the activation energy for the desorption of the supported clusters increases linearly with the chain length of the SAMs. For the longest chain C-22-SAM, the activation energy reaches similar to 150kJ/mol, and the thermal desorption of the supported clusters can be considerably suppressed near room temperature. The clear chain-length-dependent thermal stability of the supported clusters observed here can be explained well in terms of the cluster penetration into the SAM matrixes.

      DOI: 10.1021/jp061806+

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    • Adiabatic electron affinities of oligophenyls: Anion photoelectron spectroscopy and density functional theory study 査読有り

      Tsuneyuki Nakamura, Naoto Ando, Yukino Matsumoto, Shunsuke Furuse, Masaaki Mitsui, Atsushi Nakajima

      CHEMISTRY LETTERS35 ( 8 ) 888 - 889   2006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:CHEMICAL SOC JAPAN  

      Adiabatic electron affinities (EA(a)'S) of seven oligophenyls: biphenyl (BP), 4-cyanobiphenyl (CNBP), o-terphenyl (o-TP), m-terphenyl (m-TP), p-terphenyl (p-TP), p-quaterphenyl (p-QP), and 1,3,5-triphenylbenzene (TPB), have been evaluated by anion photoelectron spectroscopy and density functional theory calculations. The result provides the direct determination of the EA(a) values of the isolated CNBP, p-TP, p-QP, and TPB molecules, while EA(a) of BP, o-TP, and m-TP were estimated from the extrapolation of EA(a) vs cluster size. The excellent agreement between the experimental and calculated EA(a) were obtained.

      DOI: 10.1246/cl.2006.888

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    • Electronic properties of Cs-atom doped aluminum and silicon clusters: AlnCsm and SinCsm 査読有り

      K Koyasu, M Akutsu, J Atobe, M Mitsui, A Nakajima

      CHEMICAL PHYSICS LETTERS421 ( 4-6 ) 534 - 539   2006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:ELSEVIER SCIENCE BV  

      The effect of Cs atom doping on metallic aluminum clusters and covalent silicon clusters, AlnCsm (n = 5-14, m = 0-3) and SinCsm (n = 5-16, m = 0-3), was examined by mass spectrometry and anion photoelectron spectroscopy. For clusters containing Cs atom(s), the electron affinities of both clusters are generally decreased and the following characteristic features are observed: for AlnCsm Cs-atom doping causes (1) electron filling into the electronic shell structure of the Al-n, clusters and (2) geometrical packing of icosahedral 13-atoms, while for SinCsm Cs-atom doping enhances electronic stability to be ascribed to pure Si-n clusters, particularly at (n, m) = (10, 3) and (13, 1). (c) 2006 Elsevier B.V. All rights reserved.

      DOI: 10.1016/j.cplett.2006.01.118

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    • Photoelectron spectroscopy of binary Au cluster anions with a doped metal atom: AunM- (n=2-7), M = Pd, Ni, Zn, Cu, and Mg 査読有り

      K Koyasu, Y Naono, M Akutsu, M Mitsui, A Nakajima

      CHEMICAL PHYSICS LETTERS422 ( 1-3 ) 62 - 66   2006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:ELSEVIER SCIENCE BV  

      The electronic structures of binary gold cluster anions: AunM- (M = Pd, Ni, Zn, Cu, Mg) were investigated by anion photoelectron spectroscopy at the photon energy of 4.66 eV. The spectra exhibit even-odd alternation of electron affinities and characteristic spectral changes with n, which are accountable in terms of the interactions between the Au clusters and doped metal atoms. For the binary clusters containing Pd, Ni, and Cu. their valence electrons are shared with those of the Au clusters, whereas for Mg the doped atom is weakly bound to Au clusters. A size-dependent spectral change is clearly observed for AunPd- at n approximate to 5. (c) 2006 Elsevier B.V. All rights reserved.

      DOI: 10.1016/j.cplett.2006.02.034

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    • Soft-landing isolation of vanadium-benzene sandwich clusters on a room-temperature substrate using n-alkanethiolate self-assembled monolayer matrixes 査読有り

      M Mitsui, S Nagaoka, T Matsumoto, A Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY B110 ( 7 ) 2968 - 2971   2006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  

      Gas-phase synthesized vanadium-benzene 1:2 (VBz(2)) sandwich clusters were size-selectively deposited onto bare gold and long-chain n-alkanethiolate [-S-(CH2)(n-1)-CH3; n = 16, 18, and 22] self-assembled monolayer (SAM)-coated gold substrates under ultrahigh vacuum (UHV) conditions. Investigation of the resulting deposited clusters was performed by infrared reflection absorption spectroscopy (IRAS) and thermal desorption spectroscopy (TDS). The IR frequencies of the soft-landed VBz(2) clusters show excellent agreement with the fundamentals reported in IR data of VBz(2) in an argon matrix. The analysis of IRAS spectra reveals that while there was no orientational preference of the VBz(2) clusters on a bare gold substrate, the VBz(2) clusters deposited onto the SAM substrates were highly oriented with the molecular axis 70-80 degrees tilted off the surface normal. In addition, analysis of TDS spectra revealed unusually large adsorption heats of the physisorbed VBz(2) clusters. The present results are explained by cluster penetration into the long-chain alkanethiolate SAM and for the first time demonstrate the matrix isolation of gas-phase organometallic clusters around room temperature.

      DOI: 10.1021/jp057194v

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    • Formation and photoelectron spectroscopy of nanoscale cluster anions of biphenyl, (BP)(n)(-) (n=2-100) 査読有り

      M Mitsui, Y Matsumoto, N Ando, A Nakajima

      CHEMISTRY LETTERS34 ( 9 ) 1244 - 1245   2005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)   出版者・発行元:CHEMICAL SOC JAPAN  

      Evolution of electronic structures of nanoscale biphenyl cluster anions, (BP)(n)(-) (n = 2-100), have been studied by photoelectron spectroscopy in a size-selective fashion. The energetics of vertical detachment energy (VDE) revealed negative electron affinity of a biphenyl molecule and substantial cluster reorganizations via electron attachment. Comparison of the VDE energetics with naphthalene cluster anions implied that the freezing (and/or melting) temperatures of the BP clusters may be much lower than those of naphthalene clusters.

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    • Trapping of V(benzene)(2) sandwich clusters in a n-alkanethiol self-assembled monolayer matrix 査読有り

      S Nagaoka, E Okada, S Doi, M Mitsui, A Nakajima

      EUROPEAN PHYSICAL JOURNAL D34 ( 1-3 ) 239 - 242   2005年7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:SPRINGER  

      V(benzene)(2) sandwich cluster cations produced in the gas phase were size-selectively deposited onto a self-assembled monolayer of n-hexadecanethiols (HDT-SAM) chemisorbed on a Au(111) surface as well as onto a bare Au(111) surface. The thermal chemistry of the neutralized clusters on each substrate was studied with temperature programmed desorption (TPD). From the analyses of the threshold in the TPD, the desorption activation energies of the clusters deposited were determined to be 64.4 +/- 12.8 kJ/mol for the Au(111) and 130 +/- 10 kJ/mol for the HDT-SAM. The remarkably large desorption activation energy from the SAM suggests that the deposited clusters are incorporated into the SAM matrix and firmly trapped inside the alkyl chains of the SAM.

      DOI: 10.1140/epjd/e2005-00151-4

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    • Negative ion photoelectron spectroscopy of 2,2’-bithiophene cluster anions, (2T)n- (n = 1-100) 査読有り

      M. Mitsui, Y. Matsumoto, N. Ando, A. Nakajima

      Eur. Phys. J. D34 ( 1-3 ) 169 - 172   2005年7月

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

      DOI: 10.1140/epjd/e2005-00139-0

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    • Selective formation of MSi16 (M = Sc, Ti, and V) 査読有り

      K Koyasu, M Akutsu, M Mitsui, A Nakajima

      JOURNAL OF THE AMERICAN CHEMICAL SOCIETY127 ( 14 ) 4998 - 4999   2005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:AMER CHEMICAL SOC  

      DOI: 10.1021/ja045380t

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    • Lanthanide organometallic sandwich nanowires: Formation mechanism 査読有り

      N Hosoya, R Takegami, J Suzumura, K Yada, K Koyasu, K Miyajima, M Mitsui, MB Knickelbein, S Yabushita, A Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A109 ( 1 ) 9 - 12   2005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  

      A molecular beam of europium-cyclooctatetraene sandwich nanowires Eu-n(COT)(m) was produced by a laser vaporization synthesis method. The formation mechanism of the nanowires was quantitatively revealed by photoelectron and photoionization spectroscopies of the Eu-COT species, together with supporting theoretical calculations. From these results. it is confirmed that growth processes extending the length of Eu-COT nanowires involve a series of elementary reactions in which efficient charge transfer occur at the terminal reaction sites. In every elementary step, the reaction proceeds between one reactant having low ionization energy and the other reactant having high electron affinity, probably via a "harpoon" mechanism.

      DOI: 10.1021/jp0452103

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    • Negative ion photoelectron spectroscopy of acridine molecular anion and its monohydrate 査読有り

      S Kokubo, N Ando, K Koyasu, M Mitsui, A Nakajima

      JOURNAL OF CHEMICAL PHYSICS121 ( 22 ) 11112 - 11117   2004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 INST PHYSICS  

      Negative ion photoelectron spectroscopy was employed to investigate the electronic structure of the acridine molecular anion and its monohydrated anion in the gas phase. Their adiabatic electron affinities were measured to be 0.896+/-0.010 and 1.18+/-0.05 eV, and the low-lying electronic excited states in both neutral acridine and in its monohydrate were revealed. The photoelectron spectra clearly exhibit the presence of low-lying singlet and triplet states having a (pi,pi*) configuration in an uncomplexed acridine molecule. Comparison of the photoelectron spectrum of acridine with that of anthracene shows that photodetachment processes into the excited states of (n,pi(*)) configuration have little intensity, implying a relatively large intramolecular structural relaxation in the (n,pi(*)) states. (C) 2004 American Institute of Physics.

      DOI: 10.1063/1.1818132

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    • Coexistence of two different anion states in polyacene nanocluster anions 査読有り

      M Mitsui, S Kokubo, N Ando, Y Matsumoto, A Nakajima, K Kaya

      JOURNAL OF CHEMICAL PHYSICS121 ( 16 ) 7553 - 7556   2004年10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 INST PHYSICS  

      Two types of anion states are shown to coexist in nanometer-scale polyacene cluster anions. Naphthalene and anthracene nanoclusters having a single excess electron were produced in the gas-phase. Photoelectron spectra of size-selected cluster anions containing 2 to 100 molecules revealed that rigid "crystal-like" cluster anions emerge, greater than similar to2 nanometers in size, and coexist with the "disordered" cluster anion in which the surrounding neutral molecules are reorganizing around the charge core. These two anion states appear to be correlated to negative polaronic states formed in the corresponding crystals. (C) 2004 American Institute of Physics.

      DOI: 10.1063/1.1809118

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    • Electronic structures of exohedral lanthanide-C-60 clusters 査読有り

      J Suzumura, N Hosoya, S Nagao, M Mitsui, A Nakajima

      JOURNAL OF CHEMICAL PHYSICS121 ( 6 ) 2649 - 2654   2004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:AMER INST PHYSICS  

      We have studied the electronic structures of several gas phase exohedral lanthanide (Ln)-C-60 clusters, Ln(n)C(60) (Ln=Pr, Ho, Tb, Tm, Eu, and Yb) with n=1-4, by photoionization spectroscopy of the neutrals and photoelectron spectroscopy of their anions. Both of the spectroscopic analyses reveal that most of the Ln atoms preferably take +3 oxidation states, while Eu atoms alone assume +2 oxidation states, and that C-60 accepts up to twelve donated electrons in Ln(n)C(60). An additional photoionization examination of the oxygen atom mixing into the Ln(n)C(60) clusters demonstrated that each oxygen atom reduces two electrons from C-60. This result implies that the number of accepted electrons in C-60 can be varied by a suitable choice of the number of Ln atoms and O atoms. (C) 2004 American Institute of Physics.

      DOI: 10.1063/1.1767514

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    • Photoelectron spectroscopy of pyrene cluster anions, (pyrene)(-)(n) (n=1-20) 査読有り

      N Ando, S Kokubo, M Mitsui, A Nakajima

      CHEMICAL PHYSICS LETTERS389 ( 4-6 ) 279 - 283   2004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:ELSEVIER SCIENCE BV  

      Pyrene molecular anion and its homogeneous clusters, (pyrene)(n)(-) (n = 2-20), have been studied by anion photoelectron spectroscopy. The adiabatic electron affinity (EA(a)) of pyrene was directly determined to be 0.406 +/- 0.010 eV. This EA(a) value agrees with that calculated using the method of density functional theory, showing that the excess electron occupies the lowest unoccupied molecular orbital of pyrene molecule. Photoelectron spectra of its cluster anions suggest that the excess electron in the pyrene dimer anion is delocalized over the two pyrene moieties, whereas in larger clusters the excess electron is predominantly localized on a single pyrene molecule. (C) 2004 Elsevier B.V. All rights reserved.

      DOI: 10.1016/j.cplett.2004.03.100

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    • Unusually large dynamic electron polarization in an O2(1Δg)-2,2,6,6-tetramethylpiperidine-1-oxyl radical system 査読有り

      M. Mitsui, K. Takeda, Y. Kobori, A. Kawai, K. Obi

      J. Phys. Chem. A108 ( 7 ) 1120 - 1126   2004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)  

      DOI: 10.1021/jp035235m

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    • Quenching mechanism of excited coronene by a nitroxide radical studied by probing dynamic electron polarization 査読有り

      M. Mitsui, Y. Kobori, A. Kawai, K. Obi

      J. Phys. Chem. A108   524 - 531   2004年

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      記述言語:英語   掲載種別:研究論文(学術雑誌)  

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    • Coexistence of solvated electrons and solvent valence anions in negatively charged acetonitrile clusters, (CH3CN)(n)(-) (n=10-100) 査読有り

      M Mitsui, N Ando, S Kokubo, A Nakajima, K Kaya

      PHYSICAL REVIEW LETTERS91 ( 15 ) 153002-1 - 153002-4   2003年10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 PHYSICAL SOC  

      Anion photoelectron spectroscopy of acetonitrile cluster anions, (CH3CN)(n)(-) (n=10-100), successfully demonstrates the competitive coexistence of two different anionic species: a solvated electron and a solvent-bound valence anion. The distinctly different nature of these anions is revealed by hole-burning-type photoelectron spectroscopy and relative photodetachment cross section measurements. This unusual coexistence is attributed to the closely lying nature of their anionic states at just the number of solvent molecules sufficient to almost complete the first solvation layer.

      DOI: 10.1103/PhysRevLett.91.153002

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    • Negative ion photoelectron spectroscopy of (benzene)(n)(-) (n=53-124) and (toluene)(n)(-) (n=33-139): Solvation energetics of an excess electron in size-selected aromatic hydrocarbon nanoclusters 査読有り

      M Mitsui, A Nakajima, K Kaya

      JOURNAL OF CHEMICAL PHYSICS117 ( 21 ) 9740 - 9749   2002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 INST PHYSICS  

      We present a negative ion photoelectron spectroscopic study on the solvation energetics of an excess electron in the size-selected aromatic hydrocarbon nanoclusters, (benzene)(n)(-) (n=53-124) and (toluene)(n)(-) (n=33-139). The formation and stability of these negatively charged clusters were investigated using mass spectrometry with two different sources: (1) low-energy (approximate to0.3 eV) electron attachment and (2) high-energy electron impact. The results reveal that very large coordination numbers (nsimilar to25) are necessary for the formation of stable benzene and toluene cluster anions. This suggests that the second solvation layer (effect) is essential for stable binding of the excess electron in these clusters. The energetics of the cluster anions were also explored by negative ion photoelectron spectroscopy. The photoelectron spectra obtained were related to bulk parameters, e.g., solvent reorganization energy and conduction band minimum, via an analysis of vertical detachment energies versus n(-1/3). The bulk solvent reorganization energies thus estimated have revealed the excess electron trapping levels in bulk benzene and toluene. The applicability of the generalized cluster size equation is examined in these nondipolar aromatic hydrocarbon systems for the first time. (C) 2002 American Institute of Physics.

      DOI: 10.1063/1.1516793

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    • Photoelectron spectroscopy of palladium-doped gold cluster anions; Au-n,Pd- (n=1-4) 査読有り

      K Koyasu, M Mitsui, A Nakajima, K Kaya

      CHEMICAL PHYSICS LETTERS358 ( 3-4 ) 224 - 230   2002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:ELSEVIER SCIENCE BV  

      Palladium-doped gold clusters. AunPd- (n = 1-4). were investigated using anion photoelectron spectroscopy at 4.66 eV photon energy. Electron affinities (EAs) and vertical detachment energies (VDEs) are determined, and the electronic structures of Pd-doped Au-n clusters are compared to those of pure Au-n clusters. A peak shape analysis reveals electronic and geometric similarity between Au-n(-) and Aun-1 Pd- clusters and it is found that (1) an electron promotion occurs from 4d to 5s orbital in the Pd atom, and that (2) the bond of Au-Pd is formed through sigma orbital between 6s of Au and 5s of Pd. (C) 2002 Published by Elsevier Science B.V.

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    • Mass spectra and photoelectron spectroscopy of negatively charged benzene clusters, (benzene)(n)(-) (n=53-124) 査読有り

      M Mitsui, A Nakajima, K Kaya, U Even

      JOURNAL OF CHEMICAL PHYSICS115 ( 13 ) 5707 - 5710   2001年10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 INST PHYSICS  

      Negatively charged benzene clusters, (benzene)(n)(-), were produced by injecting low- and high-energy electrons into an intense supersonic jet expansion. Threshold size of n=53 was observed by slow-electron attachment, while the smaller (benzene)(n)(-) with 2 less than or equal ton less than or equal to 52 were also observed through the fragmentation of larger (benzene)(n)(-) by high-energy electron attachment. Photoelectron spectroscopy for (benzene)(n)(-) with n=53-124 has revealed a bulklike electron solvated state in (benzene)(n greater than or equal to 53)(-) through the vertical detachment energies (VDEs) versus n(-1/3) relationship. (C) 2001 American Institute of Physics.

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    • Time resolved ESR study on the photochemical reactions of pyrene and nitroxide radical system in micelle; formation of spin-correlated pyrene cation-nitroxide pairs 査読有り

      A Kawai, A Shikama, M Mitsui, K Obi

      BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN74 ( 7 ) 1203 - 1211   2001年7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:CHEMICAL SOC JAPAN  

      Time-resolved ESR (TR-ESR) spectra were measured in the laser excitation of aromatic compounds such as xanthone, bromopyrene, fluoranthene (Flt) and pyrene (Py) in sodium dodecyl sulfate (SDS) aqueous micellar system in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). Net emission (Em) signals of triplet hyperfine (hf) lines of TEMPO were observed in xanthone- and bromopyrene-TEMPO systems. The chemically induced dynamic electron polarization (CIDEP) was explained by radical-triplet pair mechanism. Antiphase signals of TEMPO with Ern in low-field side and enhanced absorption in high-field side (EA) of each triplet hf line were superimposed on net Ern signals in Flt- and Py-TEMPO systems. The square laser power dependence of the EA signal suggests that the two-photon ionization of Flt and Py is related to the EA antiphase signal. Rate constants of the reactions occurring in SDS solution were determined by analysis of transient absorption decays in the Py-TEMPO system. The reaction rates of Py+-TEMPO and Py-3*-TEMPO in SDS solution were determined as 1.2 X 10(6) s(-1) and 3.0 X 10(5) s(-1), respectively, at the TEMPO concentration of 2 mM (M = mol dm(-3)). According to these measurements, it was concluded that the EA CIDEP is due to spin-correlated radical pair (SCRP) of TEMPO and Py+ which was formed in the electron transfer reaction from TEMPO to Py+. Simulation of TR-ESR spectra was carried out using SCRP theory. From kinetic analysis of intermediates together with the simulation of TR-ESR spectra, it was concluded that both SCRP of Py+-TEMPO and RTPM of Py-3*-TEMPO contribute to the CIDEP of TEMPO.

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    • Structure and dynamics of 9(10H)-acridone and its hydrated clusters. III. Microscopic solvation effects on nonradiative dynamics 査読有り

      M Mitsui, Y Ohshima, O Kajimoto

      JOURNAL OF PHYSICAL CHEMISTRY A104 ( 38 ) 8660 - 8670   2000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)   出版者・発行元:AMER CHEMICAL SOC  

      As the final part of the series, nonradiative dynamics and energy-level structure of relevant electronic excited states in 9(10H)-acridone (AD) and its hydrated clusters have been studied by various spectroscopic methods. Time-resolved fluorescence measurements on their (1)(pi,pi*) origin excitation have revealed that the fluorescence decay is very fast (approximate to 10 ps) for bare AD but drastically lengthened (&gt; ns) in AD-(H2O)(n) (n = 1-6 and higher). Bare AD has been observed clearly by mass-selective delayed ionization and sensitized-phosphorescence detection, which indicates the efficient formation of molecules in triplet manifold after the (1)(pi,pi*) excitation. Several weak peaks have been identified around each (1)(pi,pi*) vibronic band of bare AD, and they are attributed to (3)(n,pi*) transitions which borrow intensity from the nearby (1)(pi,pi*) bands through the direct spin-orbit coupling. Such satellite bands completely disappear in the fluorescent cluster spectra with n greater than or equal to 1. All of the experimental observations indicate that the dominant nonradiative pathway in bare AD is the S-1(pi,pi*) --&gt; T-2(n,pi*) intersystem crossing (ISC) followed by the T-2(n,pi*) --&gt; T-1(pi,pi*) internal conversion. This direct ISC process becomes prohibited by the energy-level inversion between the S-1 and T2 states induced by the H bonding to the C=O site. Thus the relaxation pathway is "switched" to the second-order ISC [S-1-(pi,pi*) --&gt; T-1(pi,pi*)] in the fluorescent hydrated clusters, where the carbonyl site is involved in H-bonding networks. Owing to the increasing S-1-T-2 separation, the fluorescence quantum yield becomes larger for the higher clusters, which is approaching to the bulk solution value, i.e., Phi(f) approximate to 1. The (pi,pi*) and (n,pi*) shifts at each cluster geometry have been calculated as (N)HOMO-LUMO gaps in DFT orbital energies to support the picture on the energy-level structure. Most importantly, a small falloff in the fluorescence decay constants from n = 2 to 3 has been definitely correlated to the crossover in H-bonding topologies (the C=O bonded --&gt; the bridged form), which has already been established in papers I and TI. The delayed ionization has identified new spectral features that are completely absent in the fluorescence excitation spectrum. They are assigned to the N-H bonded isomer(s) with n less than or equal to 3, which is at least as stable as the C=O bonded conformer(s) with the same size. The ISC in the hydrate(s) should be as fast as in bare AD, because of the lack of the S-1-T-2 level inversion. These experimental findings demonstrate the site-specific solvation effects on the electronic energy-level structure and the resultant nonradiative dynamics in the hydrated clusters of a bifunctional molecule.

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    • Structure and dynamics of 9(10H)-acridone and its hydrated clusters. II. Structural characterization of hydrogen-bonding networks 査読有り

      M Mitsui, Y Ohshima, S Ishiuchi, M Sakai, M Fujii

      JOURNAL OF PHYSICAL CHEMISTRY A104 ( 38 ) 8649 - 8659   2000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)   出版者・発行元:AMER CHEMICAL SOC  

      The present paper represents fluorescence-detected infrared measurements of 9(10H)-acridone (AD) and 10 of its fluorescent hydrated clusters, AD-(H2O), (n = 1-5 and more), which have been performed by monitoring the fluorescence from their (1)(pi,pi*) electronic origin transitions reported in paper I. In the n = 1 and 2 clusters, free N-H stretching band has been identified in addition to O-H stretching bands characteristic to water molecules acting as single proton donors. As the next solvation step, the II-bonded O-H stretches are further developed in the red-shifted region and the N-H stretch becomes involved in the hydrogen-bonds for the n = 3-5 clusters. For n greater than or equal to 6, more than one pair of double-donor O-H stretches appear. These spectral features are well correlated to the stepwise evolution in the hydrogen-bonding networks in AD-(H2O)(n), which have been predicted by the (pi,pi*) spectral-shift analysis and DFT calculations presented in paper I: water units are bound to the C=O site for n = I and 2, a single water chain bridges between the C=O and N-H sites above the AD aromatic rings for n = 3-5, and water bridges become branched for n greater than or equal to 6 and probably form three-dimensional cages at higher aggregation levels. Differences in hydrogen-bonding topologies, stabilities, and dynamical behaviors among the conformers are discussed on the basis of the experimental observations, the DFT calculations, and comparison with other hydrated aromatic clusters.

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    • Structure and dynamics of 9(10H)-acridone and its hydrated clusters. I. Electronic spectroscopy 査読有り

      M Mitsui, Y Ohshima

      JOURNAL OF PHYSICAL CHEMISTRY A104 ( 38 ) 8638 - 8648   2000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)   出版者・発行元:AMER CHEMICAL SOC  

      A series of papers (I-III) reports spectroscopic investigation on structure and dynamics of 9(10H)-acridone (AD) and its hydrated clusters. As the first part of the series, the present paper describes their lowest (1)(pi,pi*) electronic transition in the 370-400 nm region studied by fluorescence-based laser spectroscopy and mass-selective two-color resonance-enhanced two-photon ionization (2C-R2PI). Thirteen fluorescent hydrates as well as the monomer have been identified in fluorescence-excitation and UV-UV hole-burning measurements, and size assignments for relatively smaller clusters, AD-(H2O), (n = 1-6), have been conducted by 2C-R2PI. The origin bands for larger-size clusters show larger red shifts converging at ca. 2200 cm(-1) but the changes are nonmonotonic, with a substantial increase from n = 2 to 3. Density-functional-theory (DFT) calculations at the B3LYP/6-31G(d,p) level have predicted that the energy difference between the C=O and N-H bonded isomers is quite small (only approximate to 1 kcal/mol) for n = 1 and 2. The observed spectral shifts of fluorescent hydrates with n = 1 and 2 are well reproduced by the HOMO-LUMO gap in the DFT orbital energies of either of the N-H or C=O bonded isomers, leaving the definitive structural assignments to fluorescence-detected infrared spectroscopy which will be described in paper II. For the larger clusters (n 3-5), several minimum-energy structures have been identified within 2 kcal/mol in binding energy, among which the conformers with water molecules bridging between the C=O and N-H sites over the AD's aromatic rings are identified as the observed species, based on good agreement between the calculated and observed spectral shifts.

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    • The first observation of CIDEP generated through the interaction between an excited singlet oxygen molecule and a free radical 査読有り

      M Mitsui, K Takeda, Y Kobori, A Kawai, K Obi

      CHEMICAL PHYSICS LETTERS262 ( 1-2 ) 125 - 130   1996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:ELSEVIER SCIENCE BV  

      Chemically induced dynamic electron polarization (CIDEP) generated through the interaction between the lowest excited singlet oxygen molecule and 2,2,6,6,-tetramethylpiperidinyl-1-oxyl (TEMPO) radical was observed by the time-resolved ESR technique. Excited singlet oxygen molecules were produced by the triplet sensitizer through energy transfer. Absorptive electron spin polarization was generated on the free radical in the excited singlet oxygen molecule - free radical system, in which the CIDEP generation was interpreted by the radical-triplet pair mechanism with doublet precursor (DP-RTPM). The CIDEP time profile was successfully analyzed by using the Bloch equations. Quenching of O-1(2) by beta-carotene provides further evidence for DP-RTPM in the O-1(2)-TEMPO system.

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    • Absolute magnitude of spin polarization in the radical-triplet pair mechanism: CIDEP generation by level crossings in a triplet-doublet interaction 査読有り

      Y Kobori, M Mitsui, A Kawai, K Obi

      CHEMICAL PHYSICS LETTERS252 ( 5-6 ) 355 - 361   1996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:ELSEVIER SCIENCE BV  

      Chemically induced dynamic electron polarization (CIDEP) generated through the interaction of the excited tripler state of benzophenone with the 2,2,6,6,-tetramethyl-1-piperidinyloxyl (TEMPO) radical was investigated by time-resolved ESR spectroscopy in benzene solution. We carefully examined what factors control the CIDEP intensities. By comparing the CIDEP intensity of TEMPO obtained in the triplet benzophenone-TEMPO system with the intensity in the C-60-TEMPO system, the absolute magnitude of net emissive polarization was determined to be -6.9 in the unit of Boltzmann polarization. The emissive polarization is attributed to state mixing between a quarter and a doublet in the radical-tripler pair induced by the zero-field splitting interaction of the counter triplet molecule. Our result is quantitatively explained by the theory that the net CIDEP is generated predominantly in regions where the quarter and doubler levels cross. This indicates that the quenching of the excited triplet benzophenone by TEMPO in benzene can proceed via an electron-exchange interaction.

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    • 配位子保護金属クラスターの励起状態の解明と三重項増感剤としての利用

      新堀佳紀, 内田惇木, 三井正明

      ナノ学会大会講演予稿集20th   2022年

      詳細を見る

    • 配位子保護Au-Cu合金クラスターにおける励起状態経和の全容解明-光アップコンバージョン解析によるアプローチ-

      有馬大地, 新堀佳紀, 三井正明

      ナノ学会大会講演予稿集20th   2022年

      詳細を見る

    • ブタジインで一部置換した環状ヘキサ-2,7-アントリレンエチニレン誘導体の合成と[10]CPP包接

      米谷樹, 松木洋憲, 新堀佳紀, 三井正明, 茅原栄一, 山子茂, 小林健二

      日本化学会春季年会講演予稿集(Web)101st   2021年

      詳細を見る

    • チオラート保護銀クラスターを三重項増感剤に用いた近赤外-青色光アップコンバージョン

      新堀佳紀, 和田悠幹, 三井正明

      ナノ学会大会講演予稿集19th   2021年

      詳細を見る

    • 配位子保護Au<sub>2</sub>Cu<sub>6</sub>クラスターにおける励起三重項状態生成に関する研究

      有馬大地, 新堀佳紀, 三井正明

      ナノ学会大会講演予稿集19th   2021年

      詳細を見る

    • Au<sub>2</sub>Cu<sub>6</sub>クラスターの励起状態緩和過程に対するホスフィン配位子の影響

      有馬大地, 新堀佳紀, 三井正明

      分子科学討論会講演プログラム&要旨(Web)15th   2021年

      詳細を見る

    • 配位子保護金クラスターを三重項増感剤に用いた光アップコンバージョン

      和田悠幹, 新堀佳紀, 吉波拓巳, 小林健二, 三井正明

      分子科学討論会講演プログラム&要旨(Web)15th   2021年

      詳細を見る

    • 高発光性Ag<sub>13</sub>Au<sub>12</sub>クラスターの発光過程における三重項性の寄与

      三井正明, 小林有希, 有馬大地, 新堀佳紀

      分子科学討論会講演プログラム&要旨(Web)15th   2021年

      詳細を見る

    • 白金ドープ銀クラスターの光アップコンバージョン特性に対する配位子の影響

      新堀佳紀, 内田惇木, 三井正明

      分子科学討論会講演プログラム&要旨(Web)15th   2021年

      詳細を見る

    • 蛍光性有機配位子保護Au<sub>2</sub>Cu<sub>6</sub>クラスターの創製と光アップコンバージョン

      高山竜一, 有馬大地, 新堀佳紀, 吉波拓巳, 小林健二, 三井正明

      分子科学討論会講演プログラム&要旨(Web)15th   2021年

      詳細を見る

    • 環状ヘキサ-2,7-(4,5-ジアリール)アントリレンエチニレン誘導体の合成と性質

      小林健二, 永島広大, 米谷樹, 松木洋憲, 河合信之輔, 新堀佳紀, 三井正明, 茅原栄一, 山子茂

      中部化学関係学協会支部連合秋季大会講演予稿集52nd (CD-ROM)   2021年

      詳細を見る

    • チオラート保護貴金属クラスターの光物理:その理解の現状と応用 招待有り

      新堀佳紀, 三井正明

      光化学52 ( 2 )   2021年

      詳細を見る

      掲載種別:記事・総説・解説・論説等(学術雑誌)  

      J-GLOBAL

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    • Ag<sub>25</sub>クラスターの光物性に対するカウンターイオンの影響

      高橋直也, 新堀佳紀, 三井正明

      ナノ学会大会講演予稿集18th   2020年

      詳細を見る

    • Ag<sub>29</sub>クラスターの発光性・平衡特性に対するホスフィン第二配位子の効果

      高山竜一, 新堀佳紀, 三井正明

      ナノ学会大会講演予稿集18th   2020年

      詳細を見る

    • ペリレンジイミド配位子で修飾した金属クラスターの精密合成と光物性評価

      小林有希, 吉波拓巳, 新堀佳紀, 小林健二, 三井正明

      光化学討論会要旨集(CD-ROM)2019   2019年

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    • 有機微結晶における三重項-三重項消滅アップコンバージョンの発光イメージング解析

      加藤望根, 豊島勇斗, 小林健二, 三井正明

      光化学討論会要旨集(CD-ROM)2019   2019年

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    • 単一粒子発光分光によるCsPbBr<sub>3</sub>ナノ結晶の励起子緩和に対する酸素の影響

      本多秀伍, 新堀佳紀, 三井正明

      光化学討論会要旨集(CD-ROM)2019   2019年

      詳細を見る

    • 発光解析を用いた金属クラスターの平衡状態の評価

      新堀佳紀, 高橋直也, 三井正明

      光化学討論会要旨集(CD-ROM)2019   2019年

      詳細を見る

    • 発光解析に基づくAg<sub>29</sub>クラスターの配位子結合-解離反応における平衡定数の決定

      高橋直也, 新堀佳紀, 三井正明

      ナノ学会大会講演予稿集17th   2019年

      詳細を見る

    • 1分子計測による多重振子色素の固体環境下での発光挙動の解明

      三井正明, 水上俊成, 井上翔太, 小林健二

      固体・表面光化学討論会講演要旨集36th (Web)   2017年

      詳細を見る

    • 光誘起トンネル電流による界面電子移動反応分子の可視化法の開発 招待有り

      三井正明

      (財)浜松科学技術研究振興会情報誌 財団ニュース12   2011年

      詳細を見る

      記述言語:日本語   掲載種別:記事・総説・解説・論説等(商業誌、新聞、ウェブメディア)  

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    • Infrared spectroscopy and thermal desorption study of vanadium–mesitylene 1:2 sandwich clusters soft-landed onto a long-chain N-alkanethiolate self-assembled monolayer 招待有り 査読有り

      Masaaki Mitsui, Shingo Doi, Kaori Ikemoto, Shuhei Nagaoka, Atsushi Nakajima

      Latest Advances in Atomic Cluster Collisions: Structure and Dynamics from the Nuclear to the Biological Scale   199 - 204   2008年1月1日

      詳細を見る

      記述言語:英語   掲載種別:記事・総説・解説・論説等(国際会議プロシーディングズ)   出版者・発行元:Imperial College Press  

      Gas-phase synthesized vanadium-mesitylene 1:2 V(mes)2 cluster cations were size-selectively deposited onto a long-chain alkanethiolate selfassembled monolayer-coated gold substrate under ultrahigh vacuum conditions. Examination of the resultant clusters was conducted by infrared reflection absorption spectroscopy (IRAS) and temperature programmed desorption (TPD), showing the clusters molecularly adsorbed and maintaining a sandwich structure on the substrate.

      DOI: 10.1142/9781848162389_0016

      Scopus

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    • 水素終端シリコン基板に担持された金属ナノ粒子の2光子光電子分光

      中村恒幸, 松本剛士, 川端小百合, 宮島謙, 三井正明, 中嶋敦, 中嶋敦

      分子科学討論会講演要旨集(CD-ROM)1st   2007年

      詳細を見る

    • シリコン基板上に担持された金属ナノ粒子の2光子光電子分光

      中村恒幸, 松本剛士, 川端小百合, 宮島謙, 三井正明, 中嶋敦, 中嶋敦

      化学反応討論会講演要旨集23rd   2007年

      詳細を見る

    • 低次元ランタノイド有機金属ナノクラスターの生成機構と電子構造

      細谷夏樹, 竹上竜太, 矢田啓蔵, 古瀬駿介, 三井正明, KNICKELBEIN Mark B., 藪下聡, 中嶋敦

      日本化学会講演予稿集86th ( 1 )   2006年

      詳細を見る

    • 希土類多層サンドイッチ有機金属クラスターの電場偏向実験

      細谷夏樹, KNICKELBEIN Mark B., 宮島謙, 宮島謙, 三井正明, 中嶋敦, 中嶋敦

      分子構造総合討論会講演要旨集(CD-ROM)2006   2006年

      詳細を見る

    • アルミニウム-リン混合成分クラスターの幾何構造と電子状態

      古瀬駿介, 阿久津稔, 細谷夏樹, 跡部純子, 宮島謙, 宮島謙, 三井正明, 中嶋敦, 中嶋敦

      分子構造総合討論会講演要旨集(CD-ROM)2006   2006年

      詳細を見る

    • フラーレンを超える分子!?正四面体Au20クラスター 招待有り

      三井正明

      化学61   63 - 64   2006年

      詳細を見る

      記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)  

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    • π電子系有機ナノクラスター負イオンの構造相転移と電子構造 招待有り

      三井正明, 安藤直人, 松本由生乃, 中嶋敦, 茅幸二

      ナノ学会会報3 ( 2 ) 63 - 69   2005年

      詳細を見る

      記述言語:日本語   掲載種別:記事・総説・解説・論説等(大学・研究所紀要)   出版者・発行元:ナノ学会会  

      CiNii Article

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    • New World in soft-nano-materials 招待有り

      K Kaya, A Nakajima, M Mitsui

      2005 International Conference on MEMS, NANO and Smart Systems, Proceedings   231 - 232   2005年

      詳細を見る

      記述言語:英語   掲載種別:記事・総説・解説・論説等(国際会議プロシーディングズ)   出版者・発行元:IEEE COMPUTER SOC  

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    • 気相ナノクラスターの材料化を目指したソフトランディング技術とナノデザイン 招待有り

      三井正明, 中嶋敦

      化学工業55 ( 1 ) 7 - 12   2004年

      詳細を見る

      記述言語:日本語   掲載種別:記事・総説・解説・論説等(学術雑誌)   出版者・発行元:化学工業社  

      CiNii Article

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    • CIDEP in radical-singlet molecular oxygen system 査読有り

      A Kawai, M Mitsui, Y Kobori, K Obi

      APPLIED MAGNETIC RESONANCE12 ( 4 ) 405 - 410   1997年

      詳細を見る

      記述言語:英語   掲載種別:記事・総説・解説・論説等(国際会議プロシーディングズ)   出版者・発行元:SPRINGER VERLAG  

      Net absorptive CIDEP generation has been demonstrated on singlet molecular oxygen and 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxyl (OTEMPO) radical system in benzene. CIDEP generation was reasonably explained in terms of the radical-triplet pair mechanism of triplet molecular oxygen-OTEMPO pair with doublet precursor. Several excited molecule-OTEMPO systems have been investigated if this CIDEP generation contributes to their CIDEP spectra. Surprisingly strong CIDEP was produced even in the presence of trace amount of dissolved oxygen, which suggests the importance of complete degassing for CIDEP studies in general systems.

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    ▼全件表示

    書籍等出版物

    • 光化学の事典 = Encyclopedia of photochemistry

      光化学協会光化学の事典編集委員会, 伊藤, 紳三郎, 宍戸, 昌彦, 堀江, 一之, 真嶋, 哲朗( 範囲: 第9章 9.2 光電子分光)

      朝倉書店  2014年6月  ( ISBN:9784254140965

      詳細を見る

      総ページ数:xvi, 418p   記述言語:日本語

      CiNii Books

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    • Photoelectron Spectroscopy of Organic Clusters

      Masaaki Mitsui, Atsushi Nakajima( 担当: 共著)

      CRC press  2010年 

      詳細を見る

      記述言語:英語 著書種別:学術書

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    所属学協会

    共同研究・競争的資金等の研究

    • 顕微分光計測を駆使した三重項-三重項消滅アップコンバージョン固体系の空間分解分析

      日本学術振興会  科学研究費助成事業 基盤研究(C) 

      三井 正明

      詳細を見る

      2020年4月 - 2023年3月

      課題番号:20K05653

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

      三重項-三重項消滅に基づく光アップコンバージョン(UC)は、増感剤と発光体を組み合わせることにより、長波長の光を短波長の光に変換する手法であり、太陽光照射でも機能するため、太陽電池や光触媒などの効率を向上させる技術として注目されている。しかしながら、実用性の高い固体状態での高効率化が未だ実現できておらず、固体試料における増感剤と発光体の混合状態の微視的理解と制御が重要となる。本研究では、1分子レベルの発光計測が可能な顕微分光装置を用いた空間分解分析を、金属ポルフィリンの一種であるPdTPBP増感剤とアントラセン誘導体の1種であるDPAあるいはC7sDPA発光体の混合微結晶に適用し、結晶内の三重項エネルギー移動(TET)効率や増感剤・発光体の存在分布の可視化と定量評価に取り組んだ。
      PdTPBPとC7sDPAを約1:100000のモル比で混合したTHF溶液を、加熱したカバーガラス上に微量滴下し、溶媒を瞬時に蒸発させることで混合微結晶を作製した。発光イメージ測定には、C7sDPAを直接励起するための波長405 nmレーザーあるいはPdTPBPを励起するための波長640 nmレーザーを用いた。レーザー光は油浸対物レンズで回折限界まで集光して試料に照射した。試料からの発光は適切なフィルターを組み合わせることにより、発光体からのUC蛍光あるいは直接励起の蛍光を選択的に検出した。測定は全て減圧下にて行った。また、蛍光量子収率が既知のアントラセン誘導体の1分子計測を、UC測定時の光学セットアップで行うことにより、装置の検出効率を精密に評価した。UC蛍光強度の励起速度依存性測定を行い、高励起速度極限を仮定した速度論モデルを新たに構築し、結晶中における増感剤と発光体の存在量や増感剤-発光体間のTET効率を決定する解析手法を確立した。現在、この成果を国際論文誌に投稿するための準備を進めている。

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    • 有機・無機ナノ物質の光物性・励起子ダイナミクスおよびそれらを用いた光電変換デバイスに関する研究

      公益財団法人 岩谷直治記念財団  第44回(平成29年度)岩谷直治記念財団 岩谷科学技術研究助成 

      三井正明

      詳細を見る

      2018年4月 - 2019年3月

      担当区分:研究代表者  資金種別:競争的資金

      配分額:2000000円 ( 直接経費:2000000円 )

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    • 1分子計測法を駆使したヘテロ界面電荷移動への包括的アプローチ

      日本学術振興会  科学研究費助成事業 

      三井正明

      詳細を見る

      2015年4月 - 2018年3月

      課題番号:15K05398

      担当区分:研究代表者  資金種別:競争的資金

      単一分子分光を用いて、光電変換過程の舞台となる界面や膜中における色素の電荷移動ダイナミクスに関する研究を実施した。とりわけ、光誘起電荷移動に基づく蛍光ブリンキングのon-timeおよびoff-time分布の光子積算時間性の評価とそれらの分布の最尤推定法(MLE)による最良パラメータ推定とそのKolomogorov-Smirnov(KS)検定を組み合わせたMLE-KS解析によるアプローチを確立し、高分子膜中や金属酸化物半導体表面上に置かれた色素分子が示す蛍光ブリンキングの解析に適用した。その結果、高分子膜中や酸化チタン半導体界面における色素の光誘起電荷移動ダイナミクスの全容を明らかにした。

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    • 光電流顕微計測による色素増感太陽電池の特性パラメータの統計分布 と相関の解明

      公益財団法人 住友財団  住友財団2013基礎科学研究助成 

      三井正明

      詳細を見る

      2014年1月 - 2016年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 温度可変単一分子蛍光分光による励起状態反応素過程に対する構造揺ら ぎ効果の解明

      日本学術振興会  科学研究費助成事業 

      三井正明

      詳細を見る

      2012年4月 - 2015年3月

      課題番号:24550018

      担当区分:研究代表者  資金種別:競争的資金

      単一分子蛍光分光を用いて、蛍光色素の光物理化学過程に対する静的・動的不均一性の影響の解明を目的に研究を行った。その結果、1)カプセル包接によるアントラセン誘導体の項間交差過程の不均一性の抑制や光退色確率の抑制の効果(光安定性の増強)、2)ペリレンジイミド誘導体(PDI)とポリマー間の不均一な電荷移動過程の全容、3)PDI-シクロデキストリン系の蛍光ブリンキングを引き起こす光誘起反応に対する温度効果と構造揺らぎの影響を明らかにした。

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    • 光誘起トンネル電流による界面電子移動反応分子の可視化と単分子検出

      日本学術振興会  科学研究費助成事業 

      三井正明

      詳細を見る

      2011年4月 - 2012年3月

      課題番号:23655007

      担当区分:研究代表者  資金種別:競争的資金

      金属酸化物半導体表面において光誘起電子移動を効率よく起こす吸着分子を可視化するための新しい方法論の開発を行った。ルテニウム錯体をナノポーラス酸化チタン電極に吸着させた色素増感太陽電池に対して顕微光誘起測定を行い,数nAレベルの微弱光誘起電流信号が計測可能であることを確認した。この光誘起電流計測と回折限界レーザースポットの 2次元ラスター走査を同期させたシステムを構築し,超高速界面電子移動を行う吸着種の単分子レベルの検出に向けた方法論の基盤を確立した。

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    • 低温マトリクス単離顕微分光による単一分子ナノ集合体の光物性の解明

      日本学術振興会  科学研究費助成事業 

      三井正明

      詳細を見る

      2008年4月 - 2012年3月

      課題番号:20685001

      担当区分:研究代表者  資金種別:競争的資金

      配分額:19700000円 ( 直接経費:14329000円 、 間接経費:5371000円 )

      単一分子計測が可能な温度可変レーザー走査顕微分光装置を開発し,それを用いた分子・分子ナノ集合体の光物性と励起状態ダイナミクスに関する研究を推進した。それにより次の成果を得た。1)発光材料として有望なアントラセン誘導体に対して,高分子薄膜中における励起三重項寿命,項間交差収率,光退色量子収率を定量的に決定した。2)テトラセンとp-ターフェニルを組み合わせた複合有機ナノ粒子中における電子励起エネルギー移動を調べ,この系における非常に高効率なエネルギー移動の原因を理論的に解明した。3)シクロデキストリン薄膜中におけるペリレン誘導体の光誘起反応を単一分子分光によって調べ,この系では包接錯体内で水素原子移動反応が起こっていることを示唆する結果を初めて見出した。

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    • 光誘起トンネル電流による界面電子移動反応分子の可視化法の開発

      (財)浜松科学技術研究振興会  天野工業技術研究所基金研究助成金 

      三井正明

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      2010年1月 - 2011年3月

      担当区分:研究代表者  資金種別:競争的資金

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    • 機能性有機分子の低次元π電子ナノネットワーク構造の生成と評価

      文部科学省  科学研究費助成事業 

      三井正明

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      2008年4月 - 2010年3月

      課題番号:20050011

      担当区分:研究代表者  資金種別:競争的資金

      ・光増感型複合π電子系有機ナノ結晶の光物理化学過程と光物性の解明
      異なるπ電子系有機分子を光励起エネルギーのドナー(D)とアクセプター(A)として複合化した光増感型複合有機ナノ結晶を新たな分子ナノ集合系として生成し,そのDおよびA蛍光強度のDA混合比依存性(A/D=10^<-6>~10^<-1>)を定量的に評価した。複合ナノ結晶におけるDA間およびAA間のForster半径を見積もり,Forster励起エネルギー移動(FRET)効率のA/D値依存性を与えるモデルをForster理論に基づいて独自に構築した。さらにそれらをForster理論に基づいて構築したモデルによって解析し,DA,AA間のFRET効率のDA混合比依存性を明らかにした。これにより蛍光強度比のA/D値依存性を1つのパラメーターのみで非常に良く再現することに成功した。その結果,この系では光合成系のような2桁以上におよび光吸収断面積の増大効果によってA分子の励起状態を限られたナノ空間に高密度に生成させることができ,それを利用することでAA間の励起子対消滅効率を制御できることを明らかにした。この結果から,光増感型複合有機ナノ結晶が高効率な単一光子発生源として振る舞う可能性を示唆された。
      ・単一分子ナノ集合体の光子相互相関測定法の開発
      昨年度,独自に開発したレーザー走査顕微蛍光分光装置に,新たにHanbury-Brown-Twiss型光子相互相関計測システムを導入した。この装置では無偏光ビームスプリッターで1:1に分割した信号光子を2つの単一光子検出器でそれぞれ検出し,光子到達時間間隔のヒストグラムを時間相関単一光子計数法によって測定する。現在までに,連続光を励起光源とした光子相互相関測定に成功し,単一π電子系分子ナノ集合体の光子アンチバンチング挙動を調べることが可能となった。

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    • 光導波路分光法による担持有機金属ナノクラスターの光物性の解明

      日本学術振興会  科学研究費助成事業 基盤研究(A) 

      中嶋 敦, 三井 正明, 長岡 修平

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      2007年 - 2010年

      課題番号:19205004

      配分額:49660000円 ( 直接経費:38200000円 、 間接経費:11460000円 )

      ソフトランディング単離法を用いて、低次元ネットワーク構造を有する有機金属ナノクラスターを単離・担持し、配向を含めた吸着構造を制御するとともに、有機金属ナノクラスターの光物性を解明した。この研究のために、光導波路分光システムなどを新しく設計製作し、有機金属クラスターの担持状態を評価した。希土類有機金属サンドイッチクラスターの大量合成手法を確立し、発光特性を蛍光分光法により検証してユウロピウム有機金属クラスターに可視光応答性を見出した。

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    • サイズ選択的電子状態プローブによる有機ナノ集合体の新奇な構造相転 移現象の探索

      日本学術振興会  科学研究費助成事業 

      三井正明

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      2005年4月 - 2007年3月

      課題番号:17750016

      担当区分:研究代表者  資金種別:競争的資金

      本最終年度では、高変換効率ラマンシフターの開発とπ電子系有機分子や核酸塩基の有機ナノ集合体の電子構造を負イオン光電子分光法によってサイズ選択的に調査した。さらに量子化学計算によって電子局在性や集合構造についても検討し、以下に述べるような成果を得た。
      (1)高変換効率ラマンシフターの開発
      50気圧以上で使用可能な高圧水素ガスラマンシフターを製作した。インジェクションシーダーを用いたNd^+:YAGレーザー一光の基本波(1064nm)ならびに2倍波(532nm)の後方散乱ストークス、反ストークス光を、10%程度の高変換効率を達成し、光電子分光測定におけるレーザー光源として使用することを可能とした。
      (2)有機ナノ集合体の電子状態と集合構造の協同性の解明
      オリゴフェニレンをはじめとするπ電子系分子が数〜数百個集合したナノ集合体負イオンの電子状態を系統的に研究した。その結果、集合数が増加するに従って電子局在性と集合構造の協同的な振る舞いの顕在化が、「二つの電子・幾何構造異性体の共存」という現象を通じて初めて見出された。これら二つの異性体の生成比は、集合体の温度によって劇的に変化し、さらに空間異方的なπ-π相互作用がこの協同現象発現に重要であることが分かった。
      チミンなどの核酸塩基で構成されるナノ集合体負イオンにおいて、集合数が増加するにつれて電荷局在状態と集合構造が協同的に転移することを初めて見出した。集合数が5分子以下では、余剰電荷は塩基1分子に強く局在化し、残りの塩基がそれを安定化する溶媒分子として振舞うことが分かった。このときの塩基は非水素結合相互作用によって結合しており、余剰電荷の存在が塩基問の水素結合形成を阻害していることが分かった。しかしながら、塩基が6分子以上集合すると、余剰電子が多点水素結合で結合したWatson-Crick型ダイマー内で非局在化している構造体へと構造転移することが分かった。この電子局在性と集合構造の協同性は、DNAの電荷移動機構の微視的理解へと繋がる興味深い結果である。

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    • 分子凝集および液滴粉砕による分子クラスターの気相合成とその物性 解明

      日本学術振興会  科学研究費助成事業 

      三井正明

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      2002年4月 - 2005年3月

      課題番号:14740332

      担当区分:研究代表者  資金種別:競争的資金

      本年度、オリゴアセン、オリゴフェニレンなどの一連のπ電子系有機化合物で構成されるナノクラスター負イオンに対して光電子分光法によるサイズ選択的な電子構造の観測を系統的に行い、以下に述べるような成果を得た。
      (1)ナフタレンやアントラセンなどのオリゴアセン化合物で構成されるナノメートルスケールの集合体(構成分子数が30個程度以上)に対して余剰電子を付着させると、余剰電子によって誘起される梼造緩和の程度が大きく異なる二つの安定状態が生成することを光電子分光法による電子構造の観測から初めて見出した。これら二つの安定状態の生成比に対する内部温度依存性やメチル基置換基効果を系統的に調べることによって、この現象が電子付着前の中性集合体における固体的状態と液体的状態の共存を反映したものであることを明らかにした。これはバルク結晶では見られないナノメートルスケールの集合体に特有の現象であり、極微小サイズの分子集合体の集合構造形態や電子構造に対してサイズや内部温度がどのような影響を与えるのかを初めて直接的に示したものである。
      (2)ビフェニル、p-ターフェニルなどのオリゴフェニレン類のナノ集合体(2-100量体)では、オリゴアセン類とは異なり、固-液共存を反映した二つの安定負イオン状態の共存は確認されなかった。しかしながら、ビフェニルとp-ターフェニルナノクラスター負イオンに対して得られた光電子スペクトルの比較から、両者においてスペクトルの形状や幅、電子束縛エネルギーのサイズ依存性が大きく異なることが見出された。この結果は、ビフェニルでは液体的なクラスターに対する電子付着によって負イオン状態が形成されるのに対し、p-ターフェニルでは固体的クラスターに対する電子付着によって負イオン状態が生成していることを示しており、分子サイズと分子構造の異方性の増大によってナノ集合体の熱力学特性が大きく変化することを明らかにすることができた。

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    • 電子スピン分極をプローブにした活性酸素種の反応ダイナミックス

      日本学術振興会  科学研究費助成事業 特別研究員奨励費 

      三井 正明

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      1998年 - 1999年

      課題番号:97J04412

      配分額:1800000円 ( 直接経費:1800000円 )

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    産業財産権

    • 一次元多層有機金属錯体ナノ磁気素子及び一次元多層有機金属錯体

      中嶋敦, 三井正明, 宮島謙, 井上健一郎, 土居真吾, 安藤直人, 岡田英嗣, 長岡修平, マーク ニッケルバイン, 茅幸二

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      出願番号:特願2003-407075  出願日:2003年12月5日

      公開番号:特開2005-167119  公開日:2005年6月2日

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    社会貢献活動

    • レーザー光で有機色素1分子を観察してみよう

      講師, 助言・指導

      立教大学理学部  科学の未来を創る女子中高生チャレンジ・ラボ  2019年8月5日 - 2019年8月6日

      詳細を見る

    • サイエンスカフェ in 静岡

      2010年12月

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    メディア報道

    • Featured Papers: "Unravelling the origin of dual photoluminescence in Au2Cu6 clusters by triplet sensitization and photon upconversion" インターネットメディア

      Advances In Engineering  https://advanceseng.com/unravelling-origin-dual-photoluminescence-au2cu6-clusters-triplet-sensitization-photon-upconversion/  2022年9月

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      執筆者:Other 

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    • Single Atoms Make A Difference インターネットメディア

      ChemistryViews  https://www.chemistryviews.org/details/ezine/11287589/Angewandte_Chemie_62021_Single_Atoms_Make_A_Difference/  2021年6月

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      執筆者:Other 

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    • 第315回スポットライトリサーチ:配位子保護金属クラスターを用いた近赤外―可視光変換 インターネットメディア

      Chem-Station  2021年6月

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    • 「金属クラスターを用いた近赤外-可視光変換」に世界で初めて成功!

      福井新聞  https://www.fukuishimbun.co.jp/articles/-/1263636  2021年2月

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    • 「金属クラスターを用いた近赤外-可視光変換」に世界で初めて成功! 新聞・雑誌

      毎日新聞  https://mainichi.jp/articles/20210219/pls/00m/020/509000c  2021年2月

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      執筆者:本人以外 

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    • 立教大学理学部化学科 光物理化学研究室(三井研究室) 会誌・広報誌

      日本油化学会  オレオサイエンス  オレオサイエンス Vol.18:No.2  2018年2月

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      執筆者:本人 

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