Updated on 2021/06/22

写真b

 
MITSUI Masaaki
 
*Items subject to periodic update by Rikkyo University (The rest are reprinted from information registered on researchmap.)
Affiliation*
College of Science Department of Chemistry
Graduate School of Science Field of Study: Chemistry
Graduate School of Science Field of Study: Chemistry
Title*
Professor
Degree
博士(理学) ( 京都大学 )
Contact information
Mail Address
Research Theme*
  • 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。

  • Research Interests
  • 光化学

  • 物理化学

  • 分子分光学

  • Campus Career*
    • 4 2014 - Present 
      College of Science   Department of Chemistry   Professor
    • 4 2014 - Present 
      Graduate School of Science   Field of Study: Chemistry   Professor
    • 4 2014 - Present 
      Graduate School of Science   Field of Study: Chemistry   Professor
     

    Research History

    • 4 2014 - Present 
      RIKKYO UNIVERSITY   College of Science Department of Chemistry   Professor

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    • 4 2014 - Present 
      RIKKYO UNIVERSITY   Graduate School of Science Field of Study: Chemistry   Professor

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    • 4 2014 - Present 
      RIKKYO UNIVERSITY   Graduate School of Science Field of Study: Chemistry   Professor

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    • 4 2013 - 3 2014 
      Shizuoka University   Graduate School of Science

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    • 10 2007 - 3 2013 
      Shizuoka University   Faculty of Science

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    • 4 2010 - 9 2010 
      Tokyo Institute of Technology

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    • 4 2006 - 9 2007 
      Keio University   Faculty of Science and Technology

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    • 4 2002 - 3 2006 
      Keio University   Faculty of Science and Technology

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    • 8 2000 - 3 2002 
      Keio University   Faculty of Science and Technology

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    • 4 2000 - 7 2000 
      Kyoto University   Faculty of Science

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

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

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    Committee Memberships

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

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      Committee type:Academic society

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

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      Committee type:Academic society

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

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      Committee type:Academic society

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    Awards

    • 3 2006  
      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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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    • 9 2005  
      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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      Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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    Papers

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

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

      J. Phys. Chem. C122   21295 - 21307   2018

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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 Peer-reviewed

      Masaaki Mitsui, Aki Unno, Kyosuke Mori

      CHEMISTRY LETTERS46 ( 6 ) 866 - 869   6 2017

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 Peer-reviewed

      C. Harthcock, J. Zhang, W. Kong, M. Mitsui, Y. Ohshima

      J. Chem. Phys.146   134311   2017

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    • Geometric and electronic properties of Si-atom doped Al clusters: Robustness of binary superatoms against charging Peer-reviewed

      M. Akutsu, K. Koyasu, J. Atobe, K. Miyajima, M. Mitsui, H.Tsunoyama, A. Nakajima

      Phys. Chem. Chem. Phys.19   20401   2017

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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 Peer-reviewed

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

      J. Phys. Chem. A121   1577 - 1586   2017

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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 Peer-reviewed

      Masaaki Mitsui, Koji Higashi, Yohei Hirumi, Kenji Kobayashi

      JOURNAL OF PHYSICAL CHEMISTRY A120 ( 42 ) 8317 - 8325   10 2016

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 Peer-reviewed

      Masaaki Mitsui, Aki Unno, Syun Azechi

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

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 -> (CS)-C-1 ISC overcomes the (CR)-C-3 process. The resultant Weibull distribution (with A < 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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    • Synthesis and Self-assembly of Cyclic 2,7-Anthrylene Ethynylene 1,3-Phenylene Ethynylene Trimer with a Planar Conformation Peer-reviewed

      Y. Takaki, R. Ozawa, T. Kajitani, T. Fukushima, M. Mitsui, K. Kobayashi

      Chem. Eur. J.22   16760 - 16764   2016

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

      Masaaki Mitsui, Yuya Kawano, Kyosuke Mori, Naoto Wakabayashi

      LANGMUIR31 ( 25 ) 7158 - 7165   6 2015

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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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    • Encapsulation with the Protrusion of Cruciform 9,10Bis( arylethynyl) anthracene Derivatives in a Self- Assembled Boronic Ester Cavitand Capsule: Photochemical and Photophysical Properties Peer-reviewed

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

      CHEMISTRY-AN ASIAN JOURNAL9 ( 5 ) 1282 - 1290   5 2014

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 Peer-reviewed

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

      PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES13 ( 8 ) 1130 - 1136   2014

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 > 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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    • Formation and electronic structures of organoeuropium sandwich nanowires Peer-reviewed

      N. Hosoya, R. Takegami, J. Suzumura, K. Yada, K. MIyajima, M. Mitsui, M. B. Knickelbein, S. Yabushita, A. Nakajima

      J. Phys. Chem. A   2014

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    • Electronic energy transfer in tetracene-doped p-terphenyl nanoparticles: Extraordinarily high fluorescence enhancement and quenching efficiency Peer-reviewed

      Masaaki Mitsui, Yuya Kawano

      CHEMICAL PHYSICS419   30 - 36   6 2013

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 Peer-reviewed

      Masaaki Mitsui, Yuya Kawano, Ryoya Takahashi, Hiroki Fukui

      RSC ADVANCES2 ( 26 ) 9921 - 9931   2012

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 -> 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 Peer-reviewed

      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

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      Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:日本分光学会  

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

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

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

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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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    • An atomic force microscope study of vanadium-benzene sandwich clusters soft-landed on self-assembled monolayers Peer-reviewed

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

      Eur. Phy. J. D52   103 - 106   2009

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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 Peer-reviewed

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

      Eur. Phy. J. D52   99 - 102   2009

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    • Mass spectroscopic study of metal-rich K2-5(KI)(n)(+) nanoclusters Peer-reviewed

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

      JOURNAL OF MOLECULAR STRUCTURE886 ( 1-3 ) 39 - 42   8 2008

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 Peer-reviewed

      Masaaki Mitsui, Naoto Ando, Atsushi Nakajima

      JOURNAL OF PHYSICAL CHEMISTRY A112 ( 25 ) 5628 - 5635   6 2008

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 Peer-reviewed

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

      JOURNAL OF PHYSICAL CHEMISTRY C112 ( 17 ) 6891 - 6899   5 2008

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      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 Peer-reviewed

      N. Ando, M. Mitsui, A. Nakajima

      J. Chem. Phys128   154318-1 - 154318-8   2008

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

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

      J. Phys. Chem. C112   15825 - 15831   2008

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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 Peer-reviewed

      Masaaki Mitsui, Naoto Ando, Atsushi Nakajima

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

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 > 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 >= 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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    • Formation of large molecular cluster anions and elucidation of their electronic structures Invited Peer-reviewed

      Masaaki Mitsui, Atsushi Nakajima

      BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN80 ( 6 ) 1058 - 1074   6 2007

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      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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    • Electronic properties of si and ge atoms doped in clusters: InnSim and InnGem Peer-reviewed

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

      JOURNAL OF PHYSICAL CHEMISTRY A111 ( 4 ) 573 - 577   2 2007

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      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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    • Electronic and geometric stabilities of clusters with transition metal encapsulated by silicon Peer-reviewed

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

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

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      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 Peer-reviewed

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

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

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      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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    • 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 Invited Peer-reviewed

      三井正明, 中嶋敦

      Molecular Science1   A0007   2007

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    • Comprehensive photoelectron spectroscopic study of anionic clusters of anthracene and its alkyl derivatives: Electronic structures bridging molecules to bulk Peer-reviewed

      N. Ando, M. Mitsui, A. Nakajima

      J. Chem. Phys.127 ( 234305-1 ) 234305-13   2007

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    • Fabrication and characterization of a granular film consisting of size-selected silver nanoparticles: Application to a SERS substrate Peer-reviewed

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

      Eur. Phys. J. D43   155 - 158   2007

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    • Soft-landing Isolation of multidecker V2(benzene)3 complexes in an organic monolayer matrix: an infrared spectroscopy and thermal desorption study Peer-reviewed

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

      J. Am. Chem. Soc.129   1528 - 1529   2007

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    • Experimental and theoretical characterization of aluminum-based binary superatoms of Al12X and their cluster salts Peer-reviewed

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

      JOURNAL OF PHYSICAL CHEMISTRY A110 ( 44 ) 12073 - 12076   11 2006

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      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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    • Adiabatic electron affinities of oligophenyls: Anion photoelectron spectroscopy and density functional theory study Peer-reviewed

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

      CHEMISTRY LETTERS35 ( 8 ) 888 - 889   8 2006

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

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

      JOURNAL OF PHYSICAL CHEMISTRY B110 ( 32 ) 16008 - 16017   8 2006

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      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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    • Electronic properties of Cs-atom doped aluminum and silicon clusters: AlnCsm and SinCsm Peer-reviewed

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

      CHEMICAL PHYSICS LETTERS421 ( 4-6 ) 534 - 539   4 2006

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      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 doped metal of M = Pd, Ni, Zn, Cu, and Mg: AunM- (n = 2-7) Peer-reviewed

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

      Chem. Phys. Lett.422   62 - 66   2006

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    • Soft-landing isolation of vanadium-benzene sandwich clusters on a room-temperature substrate using n-alkanethiolate self-assembled monolayer matrices Peer-reviewed

      M. Mitsui, S. Nagaoka, T. Matsumoto, A. Nakajima

      J. Phys. Chem. B110   2968 - 2971   2006

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    • Formation and photoelectron spectroscopy of nanoscale cluster anions of biphenyl, (BP)(n)(-) (n=2-100) Peer-reviewed

      M Mitsui, Y Matsumoto, N Ando, A Nakajima

      CHEMISTRY LETTERS34 ( 9 ) 1244 - 1245   9 2005

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      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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    • Selective formation of MSi16 (M = Sc, Ti, and V) Peer-reviewed

      K Koyasu, M Akutsu, M Mitsui, A Nakajima

      JOURNAL OF THE AMERICAN CHEMICAL SOCIETY127 ( 14 ) 4998 - 4999   4 2005

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      DOI: 10.1021/ja045380t

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    • Lanthanide organometallic sandwich nanowires: Formation mechanism Peer-reviewed

      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   1 2005

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      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 2,2’-bithiophene cluster anions, (2T)n- (n = 1-100) Peer-reviewed

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

      Eur. Phys. J. D34   169 - 172   2005

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    • Trapping of V(benzene)2 sandwich clusters in a n-alkanethiol self-assembled monolayer matrix Peer-reviewed

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

      Eur. Phys. J. D34   169 - 172   2005

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    • Negative ion photoelectron spectroscopy of acridine molecular anion and its monohydrate Peer-reviewed

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

      JOURNAL OF CHEMICAL PHYSICS121 ( 22 ) 11112 - 11117   12 2004

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      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 Peer-reviewed

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

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

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      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 Peer-reviewed

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

      JOURNAL OF CHEMICAL PHYSICS121 ( 6 ) 2649 - 2654   8 2004

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      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) Peer-reviewed

      N Ando, S Kokubo, M Mitsui, A Nakajima

      CHEMICAL PHYSICS LETTERS389 ( 4-6 ) 279 - 283   5 2004

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      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 O-2((1)Delta(g))-2,2,6,6-tetramethylpiperidine-1-oxyl radical system Peer-reviewed

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

      JOURNAL OF PHYSICAL CHEMISTRY A108 ( 7 ) 1120 - 1126   2 2004

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      Net absorptive (Abs) chemically induced dynamic electron polarization (CIDEP) is observed in the system of the lowest excited singlet molecular oxygen O-2((1)Delta(g)) and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical in benzene by means of the time-resolved ESR (TR-ESR) spectroscopy. As a result of (1) the analysis of CIDEP time profiles by the modified Bloch and kinetic equations and (2) the quenching of CIDEP by triethylamine, it is confirmed that the Abs CIDEP is created through the interaction of O-2((1)Delta(g)) with TEMPO. The creation of Abs CIDEP is reasonably interpreted in terms of the radical-triplet pair mechanism (RTPM) of the O-2((3)Sigma(g)(-))-TEMPO pair with doublet precursor. The absolute magnitude of net Abs CIDEP created on TEMPO is experimentally estimated to be 340 +/- 40 in the unit of Boltzmann polarization. To our knowledge, this is one of the largest magnitudes of CIDEP measured so far by the TR-ESR method. Based upon the RTPM theory, the origin of this unusually large CIDEP is attributed to the large spin relaxation effect via the electron spin dipole-dipole interaction of O-2((3)Sigma(g)(-)) formed in the quenching process of O-2((1)Delta(g)) by TEMPO. As a result of the discussion about the large CIDEP in O-2((1)Delta(g)) quenching by TEMPO, it is proposed that the quenching takes place through the enhanced intersystem crossing accompanied with strong electron exchange interaction between an oxygen molecule and a TEMPO radical.

      DOI: 10.1021/jp035235m

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    • Quenching mechanism of excited coronene by a nitroxide radical studied by probing dynamic electron polarization Peer-reviewed

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

      J. Phys. Chem. A108   524 - 531   2004

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

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

      Phys. Rev. Lett.91   153002-1 - 153002-4   2003

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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 Peer-reviewed

      M Mitsui, A Nakajima, K Kaya

      JOURNAL OF CHEMICAL PHYSICS117 ( 21 ) 9740 - 9749   12 2002

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      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) Peer-reviewed

      K Koyasu, M Mitsui, A Nakajima, K Kaya

      CHEMICAL PHYSICS LETTERS358 ( 3-4 ) 224 - 230   5 2002

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      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) Peer-reviewed

      M Mitsui, A Nakajima, K Kaya, U Even

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

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      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 Peer-reviewed

      A Kawai, A Shikama, M Mitsui, K Obi

      BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN74 ( 7 ) 1203 - 1211   7 2001

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      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. I. Electronic spectroscopy Peer-reviewed

      M Mitsui, Y Ohshima

      JOURNAL OF PHYSICAL CHEMISTRY A104 ( 38 ) 8638 - 8648   9 2000

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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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    • Structure and dynamics of 9(10H)-acridone and its hydrated clusters. II. Structural characterization of hydrogen-bonding networks Peer-reviewed

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

      JOURNAL OF PHYSICAL CHEMISTRY A104 ( 38 ) 8649 - 8659   9 2000

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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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    • (47) Structure and dynamics of 9(10H)-acridone and its hydrated clusters. III. Microscopic solvation effects on nonradiative dynamics Peer-reviewed

      M. Mitsui, Y. Ohshima, O. Kajimoto

      J. Phys. Chem. A104   8660 - 8670   2000

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    • The first observation of CIDEP generated through the interaction between an excited singlet oxygen molecule and a free radical Peer-reviewed

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

      CHEMICAL PHYSICS LETTERS262 ( 1-2 ) 125 - 130   11 1996

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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 Peer-reviewed

      Y Kobori, M Mitsui, A Kawai, K Obi

      CHEMICAL PHYSICS LETTERS252 ( 5-6 ) 355 - 361   4 1996

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      Language:English   Publishing type:Research paper (scientific journal)   Publisher: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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    Misc.

    • 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 Invited

      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

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      Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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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 Invited Peer-reviewed

      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   1 1 2008

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      Language:English   Publishing type:Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher: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

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    • フラーレンを超える分子!?正四面体Au20クラスター Invited

      三井正明

      化学61   63 - 64   2006

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      Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

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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 Invited

      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   63 - 69   2005

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      Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (bulletin of university, research institution)   Publisher:ナノ学会会  

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    • New World in soft-nano-materials Invited

      K Kaya, A Nakajima, M Mitsui

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

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      Language:English   Publishing type:Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher: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 Invited

      三井正明, 中嶋敦

      化学工業55   7 - 12   2004

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      Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

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    • CIDEP in radical-singlet molecular oxygen system Peer-reviewed

      A Kawai, M Mitsui, Y Kobori, K Obi

      APPLIED MAGNETIC RESONANCE12 ( 4 ) 405 - 410   1997

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      Language:English   Publishing type:Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher: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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    Books and Other Publications

    • Photoelectron Spectroscopy of Organic Clusters

      Masaaki Mitsui, Atsushi Nakajima( Role: Joint author)

      CRC press  2010 

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      Language:English Book type:Scholarly book

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    Professional Memberships

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    Research Projects

    • 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

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      4 2018 - 3 2019

      Authorship:Principal investigator  Grant type:Competitive

      Grant amount:\2000000 ( Direct Cost: \2000000 )

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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

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      4 2015 - 3 2018

      Authorship:Principal investigator  Grant type:Competitive

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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

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      1 2014 - 3 2016

      Authorship:Principal investigator  Grant type:Competitive

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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

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      4 2012 - 3 2015

      Authorship:Principal investigator  Grant type:Competitive

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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

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      4 2011 - 3 2012

      Authorship:Principal investigator  Grant type:Competitive

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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

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      4 2008 - 3 2012

      Authorship:Principal investigator  Grant type:Competitive

      Grant amount:\19700000 ( Direct Cost: \14329000 、 Indirect Cost:\5371000 )

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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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      1 2010 - 3 2011

      Authorship:Principal investigator  Grant type:Competitive

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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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      4 2008 - 3 2010

      Authorship:Principal investigator  Grant type:Competitive

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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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      4 2005 - 3 2007

      Authorship:Principal investigator  Grant type:Competitive

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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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      4 2002 - 3 2005

      Authorship:Principal investigator  Grant type:Competitive

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    Industrial property rights

    • 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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      Application no:特願2003-407075  Date applied:5 12 2003

      Announcement no:特開2005-167119  Date announced:2 6 2005

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    Social Contribution

    • サイエンスカフェ in 静岡

      12 2010

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