Updated on 2024/02/15

写真a

 
KATAYAMA Kenji
 
Organization
Faculty of Science and Engineering Professor
Other responsible organization
Applied Chemistry Course of Graduate School of Science and Engineering, Master's Program
Applied Chemistry Course of Graduate School of Science and Engineering, Doctoral Program
Contact information
The inquiry by e-mail is 《here
External link

Degree

  • 工学博士 ( 東京大学 )

  • 工学修士 ( 東京大学 )

Education

  • 1999.3
     

    The University of Tokyo   Graduate School, Division of Engineering   doctor course   withdrawn before completion

  • 1998.3
     

    The University of Tokyo   Graduate School, Division of Engineering   master course   completed

  • 1996.3
     

    The University of Tokyo   Faculty of Engineering   graduated

Research History

  • 2016 - 2019

    Japan Science and Technology Agency   PRESTO

  • 2012.4 -  

    中央大学理工学部教授

  • 2007.4 - 2012.3

    中央大学理工学部准教授

  • 2006.4 - 2007.3

    中央大学理工学部助教授

  • 2005.4 - 2006.3

    財団法人 神奈川科学技術アカデミー 光科学重点研究室 マイクロ化学グループ 常勤研究員

  • 2003.9 - 2005.3

    日本学術振興会 海外特別研究員 マサチューセッツ工科大学 化学科 博士研究員

  • 1999.4 - 2004.3

    東京大学大学院 新領域創成科学研究科 物質系専攻 助手

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Professional Memberships

  • American Chemical Society

  • 日本分析化学会 学生会員

  • 日本化学会 学生会員

  • 日本表面科学会 学生会員

  • 日本表面科学会

  • 日本化学会

  • 日本分光学会

  • Secretary of 11th international conference on photothermal and photoacoustic phenomena

  • 応用物理学会

  • 日本分析化学会

  • SPIE

  • 光化学協会

  • 化学工学会

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Research Interests

  • Spectroscopy Photochemistry

  • Analytical Chemistry

Research Areas

  • Nanotechnology/Materials / Nanostructural physics  / Nanostructural physics

  • Informatics / Computational science  / Computational science

  • Nanotechnology/Materials / Analytical chemistry  / Analytical chemistry

  • Nanotechnology/Materials / Fundamental physical chemistry  / 物理化学

Papers

  • Elucidating the Role of Surface Energetics on Charge Separation during Photoelectrochemical Water Splitting

    Zhenhua Pan, Vikas Nandal, Yuriy Pihosh, Tomohiro Higashi, Tian Liu, Jason A. Röhr, Kazuhiko Seki, Chiheng Chu, Kazunari Domen, Kenji Katayama

    ACS Catalysis   14727 - 14734   2022.11

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    Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society (ACS)  

    DOI: 10.1021/acscatal.2c04225

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  • BiVO4-Dotted WO3 Photoanode with an Inverse Opal Underlayer for Photoelectrochemical Water Splitting

    Yuhei Taga, Zhenhua Pan, Kenji Katayama, Woon Yong Sohn

    ACS Applied Energy Materials   5 ( 5 )   5750 - 5755   2022.4

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    Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society (ACS)  

    DOI: 10.1021/acsaem.2c00075

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  • Microscopic Interfacial Charge Transfer at Perovskite/Hole Transport Layer Interfaces Clarified Using Pattern-Illumination Time-Resolved Phase Microscopy

    Tatsuya Chugenji, Zhenhua Pan, Kenji Katayama

    The Journal of Physical Chemistry C   126 ( 17 )   7548 - 7555   2022.4

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    DOI: 10.1021/acs.jpcc.2c00954

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  • Distinction and Separation of Different Types of Charge Carriers from the Time-Resolved Local Charge Carrier Mapping for Photocatalytic Materials

    Kei Kawaguchi, Tatsuya Chugenji, Sayuri Okunaka, Hiromasa Tokudome, Kenji Katayama

    The Journal of Physical Chemistry C   126 ( 15 )   6646 - 6652   2022.4

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    DOI: 10.1021/acs.jpcc.2c00798

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  • Overall photosynthesis of H2O2 by an inorganic semiconductor Reviewed

    Tian Liu, Zhenhua Pan, Junie Jhon, M. Vequizo, Kosaku Kato, Binbin Wu, Akira Yamakata, Kenji Katayama, Baoliang Chen, Chiheng Chu, Kazunari Domen

    Nature Communications   13 ( 1 )   1034   2022.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Nature Publishing Group  

    Artificial photosynthesis of H2O2 using earth-abundant water and oxygen is a promising approach to achieve scalable and cost-effective solar fuel production. Recent studies on this topic have made significant progress, yet are mainly focused on using organic polymers. This set of photocatalysts is susceptible to potent oxidants (e.g. hydroxyl radical) that are inevitably formed during H2O2 generation. Here, we report an inorganic Mo-doped faceted BiVO4 (Mo:BiVO4) system that is resistant to radical oxidation and exhibits a high overall H2O2 photosynthesis efficiency among inorganic photocatalysts, with an apparent quantum yield of 1.2% and a solar-to-chemical conversion efficiency of 0.29% at full spectrum, as well as an apparent quantum yield of 5.8% at 420 nm. The surface-reaction kinetics and selectivity of Mo:BiVO4 were tuned by precisely loading CoOx and Pd on {110} and {010} facets, respectively. Time-resolved spectroscopic investigations of photocarriers suggest that depositing select cocatalysts on distinct facet tailored the interfacial energetics between {110} and {010} facets and enhanced charge separation in Mo:BiVO4, therefore overcoming a key challenge in developing efficient inorganic photocatalysts. The promising H2O2 generation efficiency achieved by delicate design of catalyst spatial and electronic structures sheds light on applying robust inorganic particulate photocatalysts to artificial photosynthesis of H2O2.

    DOI: 10.1038/s41467-022-28686-x

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  • Investigation of the Photo-Excited Charge Carrier Dynamics in Bismuth Vanadate (BiVO4) Photoanode by the Heterodyne Transient Grating Technique Reviewed

    A. Minato, K. Katayama, W. Y. Sohn

    Journal of Photochemistry and Photobiology A   424   113659   2022.2

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    DOI: 10.1016/j.jphotochem.2021.113659

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  • Photocontrollable Crystallization at the Topological Defect of a Liquid Crystalline Droplet Reviewed

    Y. Sakai, H. Kusaki, K. Katayama

    ACS Omega   6 ( 50 )   35050 - 35056   2021.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

    DOI: 10.1021/acsomega.1c05816

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  • Charge carrier mapping for Z-scheme photocatalytic water-splitting sheet via categorization of microscopic time-resolved image sequences

    Makoto Ebihara, Takeshi Ikeda, Sayuri Okunaka, Hiromasa Tokudome, Kazunari Domen, Kenji Katayama

    Nature Communications   12 ( 1 )   2021.12

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    Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media {LLC}  

    DOI: 10.1038/s41467-021-24061-4

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  • Defocus-Induced Phase Contrast Enhancement in Pattern Illumination Time-resolved Phase microscopy Reviewed

    K. Katayama, T. Chugenji, K. Kawaguchi

    AIP Advances   11   115215   2021.11

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  • Controlled Formation of Topological Defects of Liquid Crystals in Micro-Wells Reviewed

    H. Sakanoue, S. Yamashita, T. Murakami, H. Suzuki, K. Katayama

    Liquid Crystals   2021.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Taylor & Francis  

    DOI: 10.1080/02678292.2021.1991016

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  • Charge Carrier Trapping during Diffusion Generally Observed for Particulate Photocatalytic Substrates Reviewed

    K. Katayama, T. Chugenji, K. Kawaguchi

    Energies   14 ( 21 )   7011   2021.10

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

    DOI: 10.3390/en14217011

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  • Analysis of Molecular Disordering Processes in the Phase Transition of Liquid Crystals Observed by Patterned-Illumination Time-Resolved Phase Microscopy

    Nozomi Sato, Kenji Katayama

    Materials   2021.9

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.3390/ma14195491

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  • Charge Carrier Inhomogeneity of MAPbI3 Clarified by the Clustering of the Time-Resolved Microscopic Image Sequence

    Tatsuya Chugenji, Makoto Ebihara, Kenji Katayama

    ACS Applied Energy Materials   4 ( 7 )   6430 - 6435   2021.7

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    Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society ({ACS})  

    DOI: 10.1021/acsaem.1c00258

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  • Inference of molecular orientation/ordering change nearby topological defects by the neural network function from the microscopic color information Reviewed

    H. Sakanoue, Y. Hayashi, K. Katayama

    Scientific Reports   11   9108   2021.4

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Nature Publishing Group  

    DOI: 10.1038/s41598-021-88535-7

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  • Enhanced Photoelectrochemical Water Splitting Efficiency of Hematite (α-Fe2O3)-Based Photoelectrode by the Introduction of Maghemite (γ-Fe2O3) Nanoparticles Reviewed

    T. Tokubuchi, R. I. Arbi, P. Zhenhua, K. Katayama, A. Turak, W. Y. Sohn

    Journal of Photochemisty and Photobiology A   410   113179   2021.1

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  • Multivariate curve resolution combined with estimation by cosine similarity mapping of analytical data

    Yuya Nagai, Kenji Katayama

    The Analyst   2021

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    Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry ({RSC})  

    DOI: 10.1039/D1AN00362C

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  • Time-Resolved Spectroscopic Study of Photo-Excited Charge Carrier Dynamics in Hematite (-Fe2O3): Effect of Re-Growth Treatment Reviewed

    Y. Taga, K. Katayama, W. Y. Sohn

    Journal of Photochemistry and Photobiology A   408   113107   2020.12

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

    DOI: 10.1016/j.jphotochem.2020.113107

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  • Demonstration of rewritable hologram by using photo-induced optical nonlinearity in liquid crystals

    Minako Miyagawa, Woon Yong Sohn, Kenji Katayama

    Molecular Crystals and Liquid Crystals   2020.11

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.1080/15421406.2020.1856509

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  • Anomalous charge carrier decay spotted by the clustering of time-resolved microscopic phase image sequence Reviewed

    Makoto Ebihara, Kenji Katayama

    Journal of Physical Chemistry C   124 ( 43 )   23551 - 23557   2020.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

    DOI: 10.1021/acs.jpcc.0c07609

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  • Photo-excited charge carrier imaging by time-resolved pattern illumination phase microscopy Invited Reviewed

    Kenji Katayama

    Journal of Chemical Physics   153   054201   2020.8

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    Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:American Institute of Physics  

    DOI: 10.1063/5.0009312

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  • Photo-controllable rotational motion of cholesteric liquid crystalline droplets in a dispersion system Reviewed

    Y. Sakai, W. Y. Sohn, K. Katayama

    RSC Advances   10   21191 - 21197   2020.6

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  • Cooperative Effects of Surface and Interface Treatments in Hematite (a-Fe2O3) Photo-Anode on Its Photo-Electrochemical Performanc Reviewed

    M. Inaba, K. Katayama, W. Y. Sohn

    Sustainable Energy & Fuels   2020.1

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Royal Society of Chemistry  

    DOI: 10.1039/C9SE01081E

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  • An Initial Estimation Method Using Cosine Similarity for Multivariate Curve Resolution: Application to NMR Spectra of Chemical Mixtures. Reviewed

    Nagai, Yuya, Woon Yong Sohn, Kenji Katayama

    Analyst   144 ( 20 )   5986 - 5995   2019.10

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  • Optical Motion Control of Liquid Crystalline Droplets by Host–Guest Molecular Interaction Reviewed

    Sakai, Yota, Woon Yong Sohn, Kenji Katayama

    Soft Matter   15 ( 36 )   7159 - 7156   2019.9

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  • Molecular Orientation Change Nearby Topological Defects Observed by Photo-Induced Polarization/Phase Microscopy Reviewed

    Sakanoue, Haruka, Woon Yong Sohn, Kenji Katayama

    ACS Omega   4 ( 9 )   13936 - 13942   2019.8

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  • Lifetime Mapping of Photo-Excited Charge Carriers by the Transient Grating Imaging Technique for Nano-Particulate Semiconductor Films Reviewed

    Ebihara, Makoto, Woon Yong Sohn, Kenji Katayama

    Review of Scientific Instruments   90 ( 7 )   073905   2019.7

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  • Origin of Optical Nonlinearity of Photo-Responsive Liquid Crystals Revealed by Transient Grating Imaging Reviewed

    Katayama, Kenji, Daiki Kato, Kin-Ichiro Nagasaka, Minako Miyagawa, Woon Yong Sohn, Kuang-Wu Lee

    Scientific Reports   9 ( 1 )   5754   2019.4

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  • Uncovering Photo-Excited Charge Carrier Dynamics in Hematite (α-Fe2O3) Hidden in the Nanosecond Range by the Heterodyne Transient Grating Technique Combined with the Randomly Interleaved Pulse-Train Method. Reviewed

    Sohn, Woon Yong, Mika Inaba, Tsuyoshi Tokubuchi, James E. Thorne, Dunwei Wang, Kenji Katayama

    The Journal of Physical Chemistry C   123 ( 11 )   6693 - 6700   2019.3

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  • Improving Photovoltaic Performance of ZnO Nanowires Based Colloidal Quantum Dot Solar Cells via SnO2 Passivation Strategy Reviewed

    Ozu, Shuhei, Yaohong Zhang, Hironobu Yasuda, Yukiko Kitabatake, Taro Toyoda, Masayuki Hirata, Kenji Yoshino

    Frontiers in Energy Research   7   2019

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  • Effect of the conduction band offset on interfacial recombination behavior of the planar perovskite solar cells Reviewed

    Ding, Chao, Yaohong Zhang, Feng Liu, Yukiko Kitabatake, Shuzi Hayase, Taro Toyoda, Kenji Yoshino, Takashi Minemoto, Kenji Katayama, Qing Shen

    Nano Energy   53   17 - 26   2018.11

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  • Optically induced motion of liquid crystalline droplets Reviewed

    Y. Dogishi, Y. Sakai, W. Y. Sohn, K. Katayama

    Soft Matter   2018.9

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  • Aggregation-induced expansion of poly-(N-isopropyl acrylamide) solutions observed directly by the transient grating imaging technique Reviewed

    D. Kato, W, Y. Sohn, K. Katayama

    ACS Omega   3 ( 8 )   8484 - 8490   2018.7

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  • Comparative Study of Photo-Excited Charge Carrier Dynamics of Atomic Layer Deposited and Solution-Derived Hematite Films: Dependence of Charge Carrier Kinetics on Surface Orientations Reviewed

    M. Inaba, J. E. Thorne, D. Wang, W. Y. Sohn, K. Katayama

    Journal of Photochemistry and Photobiology A: Chemistry   364   645 - 649   2018.7

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  • Two-Photon Actuation of Crosslinked Liquid-Crystalline Polymers Utilizing Energy Transfer System Reviewed

    Sasaki, Shota, Toru Ube, Kenji Katayama, Masayasu Muramatsu, Hiroshi Miyasaka, Tomiki Ikeda

    Molecular Crystals and Liquid Crystals   662 ( 1 )   53 - 60   2018.6

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:TAYLOR & FRANCIS LTD  

    We prepared crosslinked azotolane liquid-crystalline polymer (LCP) films doped with a stilbene derivative (two-photon chromophore) utilizing an interpenetrating polymer network (IPN) structure. The IPN films bend toward the light source upon irradiation with femtosecond laser pulses at 600nm, which can excite the stilbene derivative by two-photon absorption. The bending speed of the IPN films increases with the square of the laser pulse intensity, which is compelling evidence for the two-photon processes.

    DOI: 10.1080/15421406.2018.1466241

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  • Surface-dominant and bulk-dominant processes in the phase recovery of liquid crystals Reviewed

    K-I. Nagasaka, W. Y. Sohn, K. Katayama

    Molecular Crystals and Liquid Crystals   663   82 - 89   2018.4

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  • Photoexcited Charge Carrier Dynamics of Interconnected TiO2 Nanoparticles: Evidence of Enhancement of Charge Separation at Anatase-Rutile Particle Interfaces Reviewed

    Shingai, Daiki, Ide, Yusuke, Sohn, Woon Yong, Katayama, Kenji

    Physical Chemistry Chemical Physics   20   3484 - 3489   2018.1

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  • Response of liquid crystals in the pre-phase transitional state Reviewed

    K. Katayama, D. Kato, K-I. Nagasaka, M. Miyagawa, W. Y. Sohn

    Molecular Crystals and Liquid Crystals   ( 657 )   89 - 94   2018.1

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  • Facile and Quick Preparation of Colloid Crystals with Micron-sized Particles by Intentionally Induced Convex Flow Reviewed

    Yoshinaga, Naoya, Nakajima, Naoto, Sohn, Woon Yong, Katayama, Kenji

    Chemistry Letters   47   1123 - 1126   2018

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  • Formation of photo-responsive liquid crystalline emulsion by using microfluidics device Reviewed

    Yoshiharu Dogishi, Shun Endo, Woon Yong Sohn, Kenji Katayama

    Entropy   19 ( 12 )   669   2017.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:MDPI AG  

    Photo-responsive double emulsions made of liquid crystal (LC) were prepared by a microfluidic device, and the light-induced processes were studied. The phase transition was induced from the center of the topological defect for an emulsion made of (N-(4-methoxybenzylidene)- 4-butylaniline (MBBA), and strange texture change was observed for an emulsion made of 4-cyano-4'- pentylbiphenyl (5CB) doped with azobenzene. The results suggest that there are defect-involved processes in the phase change of LC double emulsions.

    DOI: 10.3390/e19120669

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  • Dependences of the Optical Absorption, Ground State Energy Level, and Interfacial Electron Transfer Dynamics on the Size of CdSe Quantum Dots Adsorbed on the (001), (110), and (111) Surfaces of Single Crystal Rutile TiO2 Reviewed

    Taro Toyoda, Qing Shen, Keita Kamiyama, Kenji Katayama, Shuzi Hayase

    JOURNAL OF PHYSICAL CHEMISTRY C   121 ( 45 )   25390 - 25401   2017.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER CHEMICAL SOC  

    Quantum dots (QDs) provide an attractive alternative sensitizer to organic dyes. However, there have been few reports on QD-sensitized solar cells (QDSCs) that have photovoltaic conversion efficiencies exceeding those of dye-sensitized solar cells. This is because of the lack of fundamental studies of QDs on conventional nanocrystalline metal oxide electrodes which possess much amount of heterogeneity. An important first step is an investigation of the dependences of the optical absorption, the ground state energy level, and the interfacial electron transfer (IET) on the size of QDs deposited on well characterized single crystal oxides. The present study focuses on a system of CdSe QDs adsorbed on the (001), (110), and (111) surfaces of single crystal rutile-TiO2. The optical absorption spectra, characterized using photoacoustic spectroscopy, were found to be independent of the surface orientation concerning the optical absorption edge. The exponential optical absorption tail (Urbach tail) suggests that the disorder decreases with the increasing size of the QDs and is independent of the surface orientation. The ground state energy levels of the QDs were characterized using photoelectron yield spectroscopy. That on the (001) surface shifts upward, while that on the (110) surface shifts downward with increasing QD size. That on the (111) surface is independent of the QD size, indicating the difference of the influence of the surface orientation on adsorption of the QDs. The IET rate constant and the relaxation component were characterized. The JET rate constant was found to decrease as the size of the QDs increases and depends on the surface orientation, indicating the differences in the decrease of the free energy change and lower coupling between the excited state of CdSe QDs and the Ti 3d orbitals in rutile-TiO2. The relaxation component increases with increasing QD size and depends on the surface orientation, correlating with the density of states in the conduction band of rutile-TiO2.

    DOI: 10.1021/acs.jpcc.7b09371

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  • Slow hot carrier cooling in cesium lead iodide perovskites Reviewed

    Qing Shen, Teresa S. Ripolles, Jacky Even, Yuhei Ogomi, Koji Nishinaka, Takuya Izuishi, Naoki Nakazawa, Yaohong Zhang, Chao Ding, Feng Liu, Taro Toyoda, Kenji Yoshino, Takashi Minemoto, Kenji Katayama, Shuzi Hayase

    APPLIED PHYSICS LETTERS   111 ( 15 )   153903   2017.10

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    Lead halide perovskites are attracting a great deal of interest for optoelectronic applications such as solar cells, LEDs, and lasers because of their unique properties. In solar cells, heat dissipation by hot carriers results in a major energy loss channel responsible for the Shockley-Queisser efficiency limit. Hot carrier solar cells offer the possibility to overcome this limit and achieve energy conversion efficiency as high as 66% by extracting hot carriers. Therefore, fundamental studies on hot carrier relaxation dynamics in lead halide perovskites are important. Here, we elucidated the hot carrier cooling dynamics in all-inorganic cesium lead iodide (CsPbI3) perovskite using transient absorption spectroscopy. We observe that the hot carrier cooling rate in CsPbI3 decreases as the fluence of the pump light increases and the cooling is as slow as a few 10 ps when the photoexcited carrier density is 7 x 10(18) cm(-3), which is attributed to phonon bottleneck for high photoexcited carrier densities. Our findings suggest that CsPbI3 has a potential for hot carrier solar cell applications. Published by AIP Publishing.

    DOI: 10.1063/1.4991993

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  • Anomalous enhancement by alkylamine of the dye-sensitized solar cells using TEMPO redox Reviewed

    Taisei Nishimura, Woon Yong Sohn, Qing Shen, Shota Kuwahara, Kenji Katayama

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   346   281 - 286   2017.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE SA  

    It has been believed that the TEMPO redox cannot be used for the dye-sensitized solar cells (DSCs) using a ruthenium dye as a sensitizer. However, we found that the photovoltaic performance of DSCs was gradually improved just by keeping them in dark, and it took more than 3 weeks until the performance was saturated. We identified the reason for it; 2,2,6,6-tetramethylpiperidine (TMP) molecule, which was generated during the aging, prevented the reverse charge transfer. This was caused by the molecular interaction of TMP either with the ruthenium dyes or TEMPO redox or both. We found that the freshly prepared DSCs with a ruthenium dye can give a photovoltaic performance just by adding the piperidine additives. Furthermore, we found that not only heterocyclic amine molecules but also alkylamine molecules which do not include the ring structure show the similar effect. This result will pave the way for a novel interfacial control for the charge transfer. (C) 2017 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jphotochem.2017.06.015

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  • Optimization of Experimental Parameters for the Performance of Solid-state Dye-sensitized Solar Cells Reviewed

    Miki Yamaguchi, Taisei Nisimura, Woon Yong Sohn, Qing Shen, Shota Kuwahara, Kenji Katayama

    ANALYTICAL SCIENCES   33 ( 9 )   1041 - 1046   2017.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:JAPAN SOC ANALYTICAL CHEMISTRY  

    The effects of various sample parameters for solid-state dye sensitized solar cells were studied with carrier dynamics measurements and electrochemical measurements. Although many parameters and processes have been decided based on the experience of researchers, the chemical and physical reasons for the selections have not been clarified. We studied the effect of the generally utilized materials and processing such as the blocking layer, titanium oxide thickness, surface treatment, and the selection of dyes and hole transfer materials. Based on our findings, we were able to rationally optimize the structure of the solid-state dye sensitized solar cells in terms of cell performance or the lifetime of charge carriers.

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  • Investigation of Photoexcited Carrier Dynamics in Hematite and the Effect of Surface Modifications by an Advanced Transient Grating Technique Reviewed

    Woon Yong Sohn, Shota Kuwahara, James E. Thorne, Dunwei Wang, Kenji Katayama

    ACS Omega   2 ( 3 )   1031 - 1035   2017.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Chemical Society  

    Photoexcited carrier dynamics in a hematite film with and without amorphous NiFeOx on the surface was investigated using the heterodyne transient grating method. We found that two different electron/hole dynamics took place in the micro- and millisecond time regions and successfully assigned each component to the decay processes of electrons and holes trapped at surface states, respectively. It was also demonstrated that the amorphous NiFeOx coating plays a crucial role in increasing the survival of the holes at the surface trap states, which was caused by the decrease in the surface recombination rate.

    DOI: 10.1021/acsomega.7b00021

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  • Direct measurement of the propagation of the phase-transition region of liquid crystals Reviewed

    Takahiro Sato, Kenji Katayama

    SCIENTIFIC REPORTS   7   44801   2017.3

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:NATURE PUBLISHING GROUP  

    Many types of active matter, such as biological cells, have liquid-crystalline membranes, which are soft and flexible in their interactions with their surroundings and sometimes allow molecular-structural or -orientational changes to extend for long distances, owing to long-range molecular interactions. Despite the technological and fundamental importance of these long-range changes, there is no good physical property with which to express them for the liquid crystal. Here, we show direct measurements of the propagation of structural or orientational changes due to long-range molecular interactions in liquid crystals. We induced a patterned phase transition in a liquid crystal via illumination with a fringe pattern and observed the propagation of the phase-transition region. We determined that the propagation occurred in a ballistic manner with a velocity of 80-110 m/s and that two types of propagation-side-by-side and head-to-tail molecular interactions-were found.

    DOI: 10.1038/srep44801

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  • Specific interaction between dyes and ions in dye -sensitized solar cells observed with temporal spectral shift of dyes Reviewed

    R. Hosokawa, S. Kuwahara, K. Katayama

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   334   107 - 112   2017.2

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    Long-lived bleach responses with a lifetime of several milliseconds were found for the ruthenium and organic dyes in dye-sensitized solar cells. These responses were caused by the specific interaction between each dye and ionic species in the electrolyte. For the ruthenium and D131 dyes, iodide ions were necessary for the shift, while lithium cations induced it for D149, even though the molecular structure is quite similar for D131 and D149. The bleach peak was caused by the blue shift of the absorption peak even after the regeneration of the dye from the dye cation, which would be induced by the composition/concentration change of the ionic species on the electrolyte side due to the redox reactions or charge compensation. The result was confirmed by the dependence of the transient absorption spectra on the, order from microsecond to millisecond on various anion and cation conditions, dye structures, and redox species. (C) 2016 Elsevier B.V. All rights reserved.

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  • Response of liquid crystals in the pre-phase transitional state Reviewed

    K. Katayama, D. Kato, K-I. Nagasaka, M. Miyagawa, W. Y. Sohn

    Molecular Crystals and Liquid Crystals   657   89 - 94   2017

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  • マイクロ流体デバイスを用いた光応答性液晶エマルションの作製とその応答 Reviewed

    遠藤舜, 土岸義治, 片山建二

    ファインケミカル   46 ( 11 )   26 - 32   2017

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  • Charge Carrier Kinetics in Hematite with an Amorphous NiFeOx Coating in Aqueous Solutions: Dependence on Bias Voltage Reviewed

    Woon Yong Sohn, James E. Thorne, Yaohong Zhang, Shota Kuwahara, Qing Shen, Dunwei Wang, Kenji Katayama

    Journal of Photochemistry and Photobiology A   353   344 - 348   2017

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  • Photoexcited Charge Carrier Dynamics of Interconnected TiO2 Nanoparticles: Evidence of Enhancement of Charge Separation at Anatase-Rutile Particle Interfaces Reviewed

    Shingai, Daiki, Ide, Yusuke, Sohn, Woon Yong, Katayama, Kenji

    Physical Chemistry Chemical Physics   20   3484 - 3489   2017

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  • Formation of photo-responsive liquid crystalline emulsion by using microfluidics device Reviewed

    Yoshiharu Dogishi, Shun Endo, Woon Yong Sohn, Kenji Katayama

    Entropy   19 ( 12 )   669   2017

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  • Host-guest molecular interactions in the phase transition of liquid crystals Reviewed

    Takahiro Sato, Shota Kuwahara, Kenji Katayama

    MOLECULAR CRYSTALS AND LIQUID CRYSTALS   644 ( 1 )   44 - 51   2017

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    Phase transition dynamics of liquid crystal (LC) was measured by the heterodyne transient grating (HD-TG) method to clarify the difference between the photochemical and photothermal phase transitions. The phase transition was induced by the photo-excitation of different guest dyes doped in the host liquid crystals; azobenzene and solvent red were used as photochemical and photothermal dyes as guest dyes. The photochemical phase transition was partly induced even at much lower temperature than the nematic - isotropic phase transition temperature (T-NI) and the region was gradually increased as the temperature, while photothermal phase transition was induced in the whole area just when reaching T-NI. Furthermore, the anisotropic re-alignment of molecules was observed in the phase recovery process.

    DOI: 10.1080/15421406.2016.1277327

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  • Air Stable PbSe Colloidal Quantum Dot Heterojunction Solar Cells: Ligand-Dependent Exciton Dissociation, Recombination, Photovoltaic Property, and Stability Reviewed

    Yaohong Zhang, Chao Ding, Guohua Wu, Naoki Nakazawa, Jin Chang, Yuhei Ogomi, Taro Toyoda, Shuzi Hayase, Kenji Katayama, Qing Shen

    JOURNAL OF PHYSICAL CHEMISTRY C   120 ( 50 )   28509 - 28518   2016.12

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    We fabricated the long-term air stable PbSe colloidal quantum dots (CQDs) based planar heterojunction solar cells (FTO/TiO2/PbSe/Au) with relatively larger active area (0.25 cm(2)) using tetrabutylammonium iodide (TBAI, I-) as ligand in solid state ligand-exchange process. For the first time, we have achieved the whole preparation process of the device in the ambient atmosphere from PbSe CQDs collection to PbSe colloidal quantum dot solar cells (CQDSCs) fabrication, then storage and in their following measurements. Especially, TBAI-treated PbSe CQDSCs exhibited a power conversion efficiency (PCE) of 3.53% under AM 1.5 G in air, and also a remarkable long-term stability (more than 90 days) of their storage in ambient atmosphere has been identified. By contrast, 1,2-ethanedithiol (EDT), 3-mercaptopropionic acid (MPA) and cetyltrimethylammonium bromide (CTAB, Br-) treated PbSe CQDSCs were further studied. The ligand-dependent exciton dissociation, recombination, energy level shift, and air stability of PbSe CQDs treated with these different ligands were systematically investigated. It was noted that TBAI-treated PbSe CQDSCs exhibited suppressed recombination, faster charge transfer rate, and longer carrier lifetimes, which resulted in a higher PCE and long-term air stability.

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  • The effect of CdS on the charge separation and recombination dynamics in PbS/CdS double-layered quantum dot sensitized solar cells Reviewed

    Koki Sato, Keita Ono, Takuya Izuishi, Shota Kuwahara, Kenji Katayama, Taro Toyoda, Shuzi Hayase, Qing Shen

    CHEMICAL PHYSICS   478   159 - 163   2016.10

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    Quantum dot sensitized solar cells (QDSSCs) have attracted much interest due to their theoretical efficiency, predicted to be as high as 44%. However, the energy conversion efficiency of QDSSCs is still a lot lower than the theoretical value, one reason for which is the number of surface defects on the QDs. In order to improve the conversion efficiency, surface passivation of the QDs has been applied to QDSSCs. Studying the mechanism of how the surface passivation influences the photoexcited carrier dynamics is very important. In this paper, we clarify the effects of CdS passivation on electron injection, trapping and recombination in CdS passivated PbS QDSSCs (called PbS/CdS double-layered QDSSCs). We found that electron trapping and recombination can be suppressed effectively, and that the electron injection efficiency can be increased significantly by surface passivation with CdS on PbS QDSSCs. Our findings provide a better understanding of the effects of surface passivation on QDSSCs, which will prove beneficial for making further improvements in the photovoltaic properties of QDSSCs. (C) 2016 Elsevier B.V. All rights reserved.

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  • Distinction of electron pathways at titanium oxide/liquid interfaces in photocatalytic processes and co-catalyst effects Reviewed

    Shota Kuwahara, Kenji Katayama

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   18 ( 36 )   25271 - 25276   2016.9

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    Photocatalytic reactions include several different steps and routes for photoexcited carriers, and each dynamic is closely related to the reaction efficiency. Although commonly used time-resolved techniques can reveal the kinetics of photoexcited carriers, the reaction pathways are difficult to distinguish due to decay kinetics extending over many temporal orders and various contributions from the carriers and species involved. Herein, we report the distinction of the electron dynamics in the photocatalytic processes of titanium oxide through the combination of the transient grating method and maximum entropy analysis for the estimation of time constants. We were able to confirm three different carrier responses corresponding to an intrinsic recombination, an interfacial transfer or the decay of surface-trapped electrons, and the decay of polarons. Based on the responses, it appears that both gold and platinum work as good electron acceptors, but that only platinum shortened the lifetime of the polaron state due to the acceleration in the adsorption/desorption exchange of ions, which explains the shorter cycles of the photocatalytic reactions for platinum.

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  • Photocatalytic organic syntheses using a glass-milled microchip Reviewed

    A. Nakamura, K. Yoshida, S. Kuwahara, K. Katayama

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   322   35 - 40   2016.5

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    Photocatalytic reactions, typically known as difficult to control due to secondary reactions and involvement of multiple radicals, were demonstrated to be. controlled well by optimizing the reaction time and the microchip design. The glass-milled microchip has a good resistivity for the organic solutions and withstands multiple usage more than 100 times. The oxidization and reduction reactions were demonstrated and the flow considerably improved the conversion and yield. Furthermore, an imine synthesis was demonstrated as a multi-step reaction by combination of photocatalytic oxidation and reduction reactions. (C) 2016 Elsevier B.V. All rights reserved.

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  • The Electronic Structure and Photoinduced Electron Transfer Rate of CdSe Quantum Dots on Single Crystal Rutile TiO2: Dependence on the Crystal Orientation of the Substrate Reviewed

    Taro Toyoda, Witoon Yindeesuk, Keita Karniyama, Kenji Katayama, Hisayoshi Kobayashi, Shuzi Hayase, Qing Shen

    JOURNAL OF PHYSICAL CHEMISTRY C   120 ( 4 )   2047 - 2057   2016.2

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    Semiconductor quantum dots (QDs) have many desirable characteristics for use as sensitizers, such as enabling tuning of the band gap on the basis of the quantum confinement effect, a higher extinction coefficient, and facilitating charge injection as a result of the large dipole moment. Despite these potential advantages, no major advance in the efficiency of quantum-dot-sensitized solar cells (QDSCs) has yet been reported. The poor efficiency can be attributed to electron-transfer (ET) reactions that compete with the ideal energy generation cycle in QDSCs. Despite the great technological significance, the interfacial ET between QDs and inorganic species remains poorly understood. In this paper, we describe the electronic structure and the interactions between multiple sized CdSe QDs and single crystal rutile TiO2 with (001), (110), and (111) orientations. Single crystal TiO2 is well characterized and is not only ideal for comparing the amount and the structure of the QDs but is also useful for studying ET reactions. The rate of adsorption of CdSe QDs depends on the crystal orientation, although the average increase in diameter of the QDs is independent of the crystal orientation. The highest occupied molecular orbital (HOMO) level is independent of the adsorption time. On the other hand, the value of the HOMO level depends on the crystal orientation of the R-TiO2 substrate. The ET rate constant increases as the change in free energy increases and depends on the crystal orientation. This suggests that the mixing of the wave functions between the conduction band in the R-TiO2 and the lowest unoccupied molecular orbital (LUMO) level in the CdSe QDs depends on the crystal orientation.

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  • Specific Interaction between Dyes and Ions In Dye-sensitized Solar Cells Observed with Temporal Spectral Shift of Dyes Reviewed

    J. Photochem. Photobio. A   2016

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  • Distinction between reactive and non-reactive trap states in photocatalytic reactions revealed by transient grating technique Reviewed

    Kenji Katayama, Shota Kuwahara

    PHYSICAL CHEMISTRY OF INTERFACES AND NANOMATERIALS XV   9923   2016

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    It is crucial for the efficiency of photocatalytic reactions how to separate the photo-excited electrons and holes and how to utilize them at interfaces. There are two main difficulties to make these possible; variations of defects and co-catalysts. Most of the metal oxide photocatalysts have shallow and deep trap states, whose structure is always controversial. It is hard to tell which state helps reaction or not. Various co-catalysts have been applied, but also it is difficult to tell the real effect; charge separation or the surface passivation. Here, we will show the method to distinguish the defect type from the electron dynamics by using the transient grating (TG) method, which has a high sensitivity at the interface. We prepared a film sample by heating a TiO2 paste on a glass substrate. The film was contacted with a reactant solution sandwiched by another glass and a spacer. The TG method is one of the time-resolved techniques, which measures the refractive index change at the interface after shining a pulse excitation light. We could distinguish three different routes for photo-excited electrons; bulk trap (<100 ns), surface trap (1-5 us), Ti trap (0.5 - 10 s). Only the surface trap showed reactivity with reactants on the solution side. Ti trap had a longer lifetime, which was only observed when the photoexcited holes were scavenged. This trap seems to affect the cycle of the photocatalyst. This method offers simultaneous measurements of different trap states, and gives an insight of which defects have an actual reactivity.

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  • Ligand-dependent exciton dynamics and photovoltaic properties of PbS quantum dot heterojunction solar cells Reviewed

    Physical Chemistry Chemical Physics   2016

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  • Direct evidence of the molecular interaction propagation in the phase transition of liquid crystals Reviewed

    Kenji Katayama, Takahiro Sato, Shota Kuwahara

    LIQUID CRYSTALS XX   9940   2016

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    The molecular interaction sometimes propagates in a collective manner, reaching for a long distance on the order of millimeters. Such interactions have been well known in the field of strongly-correlated electron systems in a beautiful crystal interleaved by donor and acceptor layers, induced by photo-stimulus. The other examples can be found in liquid crystals (LCs), which could be found in many places in nature such as bio-membrane. Different from crystals, LCs features "softness", which enables it to be a curved structure such as a cell. In LCs, even a small molecular change would trigger the overall structural change by the propagation of the molecular interaction. Here we will show, for the first time, how long and how fast the molecular interaction propagates in LCs. The patterned phase transition was induced in a LC, causing the phase transition propagation in a controlled way and the propagation was measured with an time-resolved optical technique, called the transient grating. A LC sample doped with azobenzene was put into a thermally controlled LC cell. A grating pattern of a pulse light with 355 nm was impinged to the LC cell, and the light was absorbed by the dyes, releasing heat or photomechanical motion. We could observe the fringe spacing dependence on the phase transition response, which indicates that phase transition was delayed as the fringe spacing due to the delay by the phase transition propagation. This is the first direct evidence of the molecular interaction propagation of the LC molecules.

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  • Uncovering the charge transfer and recombination mechanism in ZnS-coated PbS quantum dot sensitized solar cells Reviewed

    Jin Chang, Takuya Oshima, Sojiro Hachiya, Konki Sato, Taro Toyoda, Kenji Katayama, Shuzi Hayase, Qing Shen

    SOLAR ENERGY   122   307 - 313   2015.12

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    In this work, the charge transfer and recombination mechanism is uncovered for the PbS/ZnS quantum dot sensitized solar cells (QDSSCs) based on nanoporous TiO2 electrodes. PbS quantum dots (QDs) were in-situ grown on TiO2 nanoparticles through the successive ionic absorption and reaction (SILAR) method, followed by the surface passivation of ZnS for the sensitized electrodes. It was observed that the ZnS coating cycles play a significant role in determining the photovoltaic parameters. The highest power conversion efficiency of 1.4% was achieved by coating 13 cycles of ZnS on TiO2/PbS electrode. It is essential to understand why and how ZnS passivation layers improve the photovoltaic performance of PbS QDSSCs. All obtained solar cells were characterized thoroughly by optical and electrical techniques. The open-circuit voltage decay technique and electrochemical impedance measurements indicated that the ZnS passivation layers significantly suppressed the charge recombination at the TiO2/electrolyte and TiO2/QD interfaces. The transient grating measurements suggested that the electron injection from PbS QDs to TiO2 was obviously enhanced by the ZnS coating layers. This could be attributed to the reduction of carrier trapping and recombination in PbS QDs after surface passivation. These beneficial effects of ZnS layers, therefore, resulted in the improved photovoltaic performances of PbS QDSSCs. This work provides better understanding on the passivation effect of ZnS layers in PbS QDSSCs, which would be beneficial for the further improvement of QDSSCs. (C) 2015 Elsevier Ltd. All rights reserved.

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  • Characterization of hot carrier cooling and multiple exciton generation dynamics in PbS Qps using an improved transient grating technique Reviewed

    Qing Shen, Kenji Katayama, Taro Toyoda

    JOURNAL OF ENERGY CHEMISTRY   24 ( 6 )   712 - 716   2015.11

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    Multiple exciton generation (MEG) dynamics in colloidal PbS quantum dots (QDs) characterized with an improved transient grating (TG) technique will be reported. Only one peak soon after optical absorption and a fast decay within 1 ps can be observed in the TG kinetics when the photon energy of the pump light hv is smaller than 2.7E(g) (E-g: band gap between LUMO and HOMO in the QDs), which corresponds to hot carrier cooling. When hv is greater than 2.7E(g), however, after the initial peak, the TG signal decreases first and soon increases, and then a new peak appears at about 2 to 3 ps. The initial peak and the new peak correspond to hot carriers at the higher excited state and MEG at the lowest excited state, respectively. By proposing a theoretical model, we can calculate the hot carrier cooling time constant and MEG occurrence time constant quantitatively. When MEG does not happen for hv smaller than 2.7E(g), hot carrier cools with a time constant of 400 fs. When MEG occurs for by larger than 2.7E(g), hot carrier cools with a time constant as small as 200 fs, while MEG occurs with a time constant of 600 fs. The detailed hot carrier cooling and MEG occurrence dynamics characterized in this work would shed light on the further understanding of MEG mechanism of various type of semiconductor QDs. (C) 2015 Science Press and Dalian Institute of Chemical Physics. All rights reserved.

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  • Blocking Effect for Carrier Transfer to Triiodide in Alkyl-Functionalized Dyes in Dye-Sensitized Solar Cell Reviewed

    Keita Omata, Shota Kuwahara, Ryo Hosokawa, Taisei Nishimura, Qing Shen, Taro Toyoda, Kenji Katayama

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   88 ( 9 )   1308 - 1313   2015.9

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    A blocking effect on the approach of electron acceptors into a dye/TiO2 electrode in a dye-sensitized solar cell was confirmed by the observation of charge dynamics at the interface when an alkyl-functionalized dye was used. It was found that the density of the adsorbed MK-2 on the TiO2 surface affected the ionic motion in an electrolyte at the interface, and that electron electrolyte recombination was suppressed with a high density of adsorbed MK-2 molecules, causing prevention of the approach of the redox ions.

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  • Evaluation of the Water-treatment Ability of Silica-doped Titanium Dioxide-coated Glass Plates Using a Cationic Coupling Reagent Based on a Flow Analytical System Reviewed

    Tsuyoshi Sugita, Masanobu Mori, Akinori Mase, Shin-nosuke Noguchi, Toru Tokutome, Kengo Fujii, Chisato Hara, Kenji Katayama, Shinji Iwamoto, Hideyuki Itabashi

    ANALYTICAL SCIENCES   31 ( 1 )   15 - 21   2015.1

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    In this study, a photocatalytic plate bound to highly dispersible silica-doped titanium dioxide (SiT) on a trimethoxysilyl-propyldiethylenetriamine (dien)-coated glass plate (dien-plate) was newly synthesized, and was evaluated by a flow analytical (FA) system, which consists of a photocatalytic reactor and a spectrophotometer, to continuously monitor the absorbance of tested chemicals. The method was not required to collect any sample solution at a constant period. The SiT-dien-plate facilitated the photodecomposition of methylene blue (MB) and indigo carmine (InC) in aqueous solutions. Notably, MB was quantitatively photo-decomposed following 18 h of UV-light irradiation, related to the electrostatic adsorption of surface-bound particles. A water-treatment ability of visible-light-responsive vanadium-modified nitrogen/silica co-doped titanium dioxide fixed on the dien-plate was also evaluated by the FA system. It clarified to decompose MB and InC under visible-light irradiation. Finally, the decomposition of a humic substance dissolved from Middle West China peaty soils by the SiT-dien-plate under UV-irradiation was assessed as applying the FA system with a photocatalytic plate.

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  • Evaluation of the Water-treatment Ability of Silica-doped Titanium Dioxide-coated Glass Plates Using a Cationic Coupling Reagent Based on a Flow Analytical System Reviewed

    Tsuyoshi Sugita, Masanobu Mori, Akinori Mase, Shin-nosuke Noguchi, Toru Tokutome, Kengo Fujii, Chisato Hara, Kenji Katayama, Shinji Iwamoto, Hideyuki Itabashi

    ANALYTICAL SCIENCES   31 ( 1 )   15 - 21   2015.1

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    In this study, a photocatalytic plate bound to highly dispersible silica-doped titanium dioxide (SiT) on a trimethoxysilyl-propyldiethylenetriamine (dien)-coated glass plate (dien-plate) was newly synthesized, and was evaluated by a flow analytical (FA) system, which consists of a photocatalytic reactor and a spectrophotometer, to continuously monitor the absorbance of tested chemicals. The method was not required to collect any sample solution at a constant period. The SiT-dien-plate facilitated the photodecomposition of methylene blue (MB) and indigo carmine (InC) in aqueous solutions. Notably, MB was quantitatively photo-decomposed following 18 h of UV-light irradiation, related to the electrostatic adsorption of surface-bound particles. A water-treatment ability of visible-light-responsive vanadium-modified nitrogen/silica co-doped titanium dioxide fixed on the dien-plate was also evaluated by the FA system. It clarified to decompose MB and InC under visible-light irradiation. Finally, the decomposition of a humic substance dissolved from Middle West China peaty soils by the SiT-dien-plate under UV-irradiation was assessed as applying the FA system with a photocatalytic plate.

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  • The cause for the low efficiency of dye sensitized solar cells with a combination of ruthenium dyes and cobalt redox Reviewed

    Keita Omata, Shota Kuwahara, Kenji Katayama, Shen Qing, Taro Toyoda, Kun-Mu Lee, Chun-Guey Wu

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   17 ( 15 )   10170 - 10175   2015

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    It has been a concern that the cobalt redox cannot give a good performance for the dye-sensitized solar cells when it is used with ruthenium dyes. The electron dynamics measurements clarified the electron loss processes, and clarified the cause. The result indicated the direct interaction between the ruthenium dyes with the cobalt redox, and it reduced the charge injection from the triplet state of the dyes to the titanium oxide, and also it increased the electron recombination process with the cobalt redox species. Both the problems of injection and recombination were solved by using the ruthenium dye with alkyl chains keeping a distance between the dye and the cobalt redox.

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  • Structural dynamics in azobenzene liquid crystal polymer films studied by microscopic time-resolved technique Reviewed

    Kenji Katayama, Shota Kuwahara, Tomiki Ikeda

    LIQUID CRYSTALS XIX   9565   2015

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    We studied the photo-induced dynamics in a LC polymer film including azobenzene by using a time-resolved and a microscopic technique. The film was confined in a liquid crystal cell, while it is a photomobile film under a free standing condition, which is triggered by the photoisomerization of azobenezene. From the result of the time-resolved measurements, the change inside the film induced by UV irradiation was highly anisotropic polarization change. Microscopic observation revealed that the film was consisted of ordered and disordered region with a patched structure, and the UV induced change was travelled in the ordered region on the order of seconds.

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  • Optical absorption, charge separation and recombination dynamics in Sn/Pb cocktail perovskite solar cells and their relationships to photovoltaic performances Reviewed

    Qing Shen, Yuhei Ogomi, Jin Chang, Taro Toyoda, Kosei Fujiwara, Kenji Yoshino, Koki Sato, Kohei Yamazaki, Masaya Akimoto, Yuki Kuga, Kenji Katayama, Shuzi Hayase

    JOURNAL OF MATERIALS CHEMISTRY A   3 ( 17 )   9308 - 9316   2015

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    The interest in organometal trihalide perovskite (CH3NH3PbI3)-based solid-state hybrid solar cells has increased in recent years due to the high efficiencies achieved, with a record of over 20%, and the simple low temperature preparation method. Further improvements in the photovoltaic performance can be obtained by increasing the light harvesting in the NIR region up to 1000 nm. Recently, successful energy harvesting up to a wavelength of 1060 nm using Sn/Pb cocktail halide based perovskite materials has been achieved. However, the energy conversion efficiency of such solar cells (less than 10%) is much lower than that of CH3NH3PbI3 based solar cells, which is due to their lower open circuit voltage (V-oc) and fill factor (FF). In order to improve this, we need to have a good understanding of the key factors governing the photovoltaic performance of these solar cells, i.e., the optical absorption, the charge separation and the recombination dynamics. Therefore, for this study, we characterized the optical absorption properties, including the bandgap and the Urbach energy, clarified the photoexcited carrier recombination dynamics in Sn/Pb cocktail perovskite (CH3NH3Sn0.5Pb0.5I3) and the charge separation and recombination dynamics at each interface in TiO2/Sn/Pb perovskite/P3HT solar cells, and lastly investigated the relationships between these and the photovoltaic performance.

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  • Optical absorption, charge separation and recombination dynamics in Sn/Pb cocktail perovskite solar cells and their relationships to photovoltaic performances Reviewed

    Qing Shen, Yuhei Ogomi, Jin Chang, Taro Toyoda, Kosei Fujiwara, Kenji Yoshino, Koki Sato, Kohei Yamazaki, Masaya Akimoto, Yuki Kuga, Kenji Katayama, Shuzi Hayase

    JOURNAL OF MATERIALS CHEMISTRY A   3 ( 17 )   9308 - 9316   2015

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    The interest in organometal trihalide perovskite (CH3NH3PbI3)-based solid-state hybrid solar cells has increased in recent years due to the high efficiencies achieved, with a record of over 20%, and the simple low temperature preparation method. Further improvements in the photovoltaic performance can be obtained by increasing the light harvesting in the NIR region up to 1000 nm. Recently, successful energy harvesting up to a wavelength of 1060 nm using Sn/Pb cocktail halide based perovskite materials has been achieved. However, the energy conversion efficiency of such solar cells (less than 10%) is much lower than that of CH3NH3PbI3 based solar cells, which is due to their lower open circuit voltage (V-oc) and fill factor (FF). In order to improve this, we need to have a good understanding of the key factors governing the photovoltaic performance of these solar cells, i.e., the optical absorption, the charge separation and the recombination dynamics. Therefore, for this study, we characterized the optical absorption properties, including the bandgap and the Urbach energy, clarified the photoexcited carrier recombination dynamics in Sn/Pb cocktail perovskite (CH3NH3Sn0.5Pb0.5I3) and the charge separation and recombination dynamics at each interface in TiO2/Sn/Pb perovskite/P3HT solar cells, and lastly investigated the relationships between these and the photovoltaic performance.

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  • The cause for the low efficiency of dye sensitized solar cells with a combination of ruthenium dyes and cobalt redox Reviewed

    Keita Omata, Shota Kuwahara, Kenji Katayama, Shen Qing, Taro Toyoda, Kun-Mu Lee, Chun-Guey Wu

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   17 ( 15 )   10170 - 10175   2015

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    It has been a concern that the cobalt redox cannot give a good performance for the dye-sensitized solar cells when it is used with ruthenium dyes. The electron dynamics measurements clarified the electron loss processes, and clarified the cause. The result indicated the direct interaction between the ruthenium dyes with the cobalt redox, and it reduced the charge injection from the triplet state of the dyes to the titanium oxide, and also it increased the electron recombination process with the cobalt redox species. Both the problems of injection and recombination were solved by using the ruthenium dye with alkyl chains keeping a distance between the dye and the cobalt redox.

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  • Study on Photocatalytic Organic Reactions Using Photocatalytic Microreactors Reviewed

    Kento Shimaoka, Shota Kuwahara, Makoto Yamashita, Kenji Katayama

    ANALYTICAL SCIENCES   30 ( 5 )   619 - 621   2014.5

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    Photocatalytic organic reactions were performed using automatic photocatalytic microreactor, where several open-end capillaries with photocatalytic materials coated inside were just soaked in a test tube including a reactant solution. Organic reactions of the alkyl radicals generated from carboxylic acids due to the photo-Kolbe reaction was studied, in analogy with the reactions using a photosensitizer. This methodology features the reusability of the reactor and an easy process for analysis due to easy separation of the reactant solution.

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  • The Dynamics of Multiple Exciton Generation in Semiconductor Quantum Dots Reviewed

    Shen, Q, Katayama, K, Toyoda, T

    15   295   2014.4

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  • Novel method of screening the oxidation and reduction abilities of photocatalytic materials Reviewed

    K. Katayama, Y. Takeda, K. Shimaoka, K. Yoshida, R. Shimizu, T. Ishiwata, A. Nakamura, S. Kuwahara, A. Mase, T. Sugita, M. Mori

    ANALYST   139 ( 8 )   1953 - 1959   2014

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    Two analytical methods for the evaluation of photocatalytic oxidation and reduction abilities were developed using a photocatalytic microreactor; one is product analysis and the other is reaction rate analysis. Two simple organic conversion reactions were selected for the oxidation and reduction. Since the reactions were one-to-one conversions from the reactant species to the product species, the product analysis was simply performed using gas chromatography, and the reactions were monitored in situ in the photocatalytic microreactor using the UV absorption spectra. The partial oxidation and reduction abilities for each functional group can be judged from the yield and selectivity, and the corresponding reaction rate, while the total oxidation ability can be judged from the conversion. We demonstrated the application of these methods for several kinds of visible light photocatalysts.

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  • Molecular dynamics in azobenzene liquid crystal polymer films by transient grating technique Reviewed

    Kenji Katayama, Tomomi Fujii, Shota Kuwahara, Takado Kiyohide, Tomiki Ikeda

    LIQUID CRYSTALS XVIII   9182   2014

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    We studied the effect of the ratio between the monomer and cross-linker molecules in the azobenene included liquid crystal polymer films by using the heterodyne transient grating (HD-TG) technique, which is one of the time-resolved measurement techniques. Depending on the ratio, the magnitude of the refractive index change, its anisotropy, and the lifetime of the cis isomer of azobenzene, generated by a UV pulse irradiation. By increasing the cross-linker ratio, the refractive index change and its anisotropy was reduced, indicating less ability for the motion, while slower lifetime was observed by increasing the monomer ratio, indicating that the film is difficult to return the original shape by a visible-light irradiation. The obtained dynamics was consistent with the functionality of the films.

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  • Role of lithium and co-existing cations in electrolyte to improve performance of dye-sensitized solar cells Reviewed

    Soichiro Taya, Shota Kuwahara, Qing Shen, Taro Toyoda, Kenji Katayama

    RSC ADVANCES   4 ( 41 )   21517 - 21520   2014

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    The performance of dye-sensitized solar cells (DSSCs) with an electrolyte including mixed cations was evaluated, and the relevant carrier dynamics were investigated by the heterodyne transient grating method. The performance of the DSSCs showed maximum conversion efficiency for an Li+ cation ratio of 75% with 25% other cations.

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  • Charge transfer and recombination at the metal oxide/CH3NH3PbClI2/spiro-OMeTAD interfaces: uncovering the detailed mechanism behind high efficiency solar cells Reviewed

    Qing Shen, Yuhei Ogomi, Jin Chang, Syota Tsukamoto, Kenji Kukihara, Takuya Oshima, Naoya Osada, Kenji Yoshino, Kenji Katayama, Taro Toyoda, Shuzi Hayase

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   16 ( 37 )   19984 - 19992   2014

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    In recent years, organometal halide perovskite-based solid-state hybrid solar cells have attracted unexpected increasing interest because of their high efficiency (the record power conversion efficiency has been reported to be over 15%) and low fabrication cost. It has been accepted that the high efficiency was mainly attributed to the strong optical absorption (absorption coefficient: 15 000 cm(-1) at 550 nm) over a broader range (up to 800 nm) and the long lifetimes of photoexcited charge carriers (in the order of 10 ns - a few 100 ns) of the perovskite absorbers. However, much of the fundamental photophysical properties of perovskite relating to the high photovoltaic performance are remained to be investigated. The charge separation and recombination processes at the material interfaces are particularly important for solar cell performances. To better understand the high efficiency of perovskite solar cells, we systematically investigated the charge separation (electron and hole injection) and charge recombination dynamics of CH3NH3PbClI2 hybrid solar cells employing TiO2 nanostructures as the electron transfer material (ETM) and spiro-OMeTAD as the hole transfer material (HTM). The measurements were carried out using transient absorption (TA) techniques on a time scale from sub-picoseconds to milliseconds. We clarified the timescales of electron injection, hole injection, and recombination processes in TiO2/CH3NH3PbClI2/spiro-OMeTAD solar cells. Charge separation and collection efficiency of the perovskite-based solar cells were discussed. In addition, the effect of TiO2 size on the charge separation and recombination dynamics was also investigated. It was found that all TiO2-based perovskite solar cells possessed similar charge separation processes, but quite different recombination dynamics. Our results indicate that charge recombination was crucial to the performance of the perovskite solar cells, which could be effectively suppressed through optimising nanostructured TiO2 films and surface passivation, thus pushing these cells to even higher efficiency.

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  • Photoexcited carrier dynamics of double-layered CdS/CdSe quantum dot sensitized solar cells measured by heterodyne transient grating and transient absorption methods Reviewed

    N. Osada, T. Oshima, S. Kuwahara, T. Toyoda, Q. Shen, K. Katayama

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   16 ( 12 )   5774 - 5778   2014

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    The charge dynamics in the double-layered quantum dot sensitized solar cell (QDSSC) was studied to clarify the reason why the cell performance was much improved by a double-layer coating, by using the heterodyne transient grating (HD-TG) and transient absorption methods, based on a previous study for a conventional QDSSC (N. Maeda et al., Phys. Chem. Chem. Phys., 2013, 15, 11006.) In the double-layered QDSSC, the layer order of CdS and CdSe affected the cell performance. When CdS is in between TiO2 and CdSe, the conversion efficiency was enhanced by 70%, while it was lowered by 50% in the opposite order. From the information on charge dynamics, it was found that electrons were efficiently injected to TiO2 by appropriate band alignment of CdS and CdSe, while only a part of the electrons were transferred to the TiO2 when the layer order was opposite. Furthermore, the reverse electron transfer does not matter for the conversion efficiency, because the process increased even for the appropriate layer order.

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  • Role of lithium and co-existing cations in electrolyte to improve performance of dye-sensitized solar cells Reviewed

    Soichiro Taya, Shota Kuwahara, Qing Shen, Taro Toyoda, Kenji Katayama

    RSC ADVANCES   4 ( 41 )   21517 - 21520   2014

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    The performance of dye-sensitized solar cells (DSSCs) with an electrolyte including mixed cations was evaluated, and the relevant carrier dynamics were investigated by the heterodyne transient grating method. The performance of the DSSCs showed maximum conversion efficiency for an Li+ cation ratio of 75% with 25% other cations.

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  • Depth-selective microscopic observation of a photomobile liquid crystal polymer under UV illumination Reviewed

    Kenji Katayama, Youngwoon Choi, Jeon Woong Kang, Zahid Yaqoob, Peter T. C. So, Tomomi Fujii, Shota Kuwahara, Kiyohide Takado, Tomiki Ikeda

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   16 ( 48 )   27074 - 27077   2014

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    By using the depth selective imaging method, we studied the UV induced change in a photomobile liquid crystalline polymer film. With 1 mu m depth resolution, each slice inside the film was selectively observed. A network-like structure mixed with the ordered and disordered regions of molecules in the middle of the film, and a rubbed polymer layer at the bottom of the film were observed. In each slice of the film, the phase change induced by UV light was observed strongly dependent on the director direction, which indicates the ordering change of the liquid crystalline molecules in the director direction. It took several tens of seconds for the ordering change caused by the collaborative interaction between the molecules. Furthermore, it was suggested that the UV induced change travelled from the bottom layer to the middle layer on the micron order.

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  • Effect of electrolyte constituents on the motion of ionic species and recombination kinetics in dye-sensitized solar cells Reviewed

    Shota Kuwahara, Soichiro Taya, Naoya Osada, Qing Shen, Taro Toyoda, Kenji Katayama

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   16 ( 11 )   5242 - 5249   2014

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    The dynamic motion of ions in electrolyte solutions and its effect on recombination was investigated by the heterodyne transient grating method in addition to transient absorption and transient photocurrent methods in dye sensitized solar cells. Realignment of ionic species at the electrode/electrolyte interface was observed after the electron injection in TiO2 on the order of ms. The process was affected by the total quantity of ionic species as well as cation species in the electrolyte. The recombination processes of the electrons were also affected by the constituents; the probability of the electron-electrolyte recombination decreased with decrease in I-2 concentration; the dominant recombination process changed from the electron-electrolyte to the electron-dye recombination by decreasing I- concentration. It is concluded that sufficient I- is necessary for the suppression of the electron-dye recombination and that sufficient I-2 is necessary for an efficient redox cycle, while low concentration of I-3(-) ions at the electrolyte/TiO2 interface is preferable to suppress the electron-electrolyte recombination. The effect of the cation size in an electrolyte solution on the charge dynamics was also investigated, and it was revealed that the steric hindrance of cations changed the penetration of ionic species into the nanoporous dye/TiO2 electrode, causing a change in the electrostatic properties at the interface. The cation dependence indicated that the presence of large-sized cations suppressed the electron-electrolyte recombination by disturbing the approach of I-3(-) paired with the cations.

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  • Disorder/reorientation dynamics of 4-methoxybenzylidene-4-n-butylaniline observed by heterodyne transient grating method Reviewed

    Takaaki Chiba, Hayato Inoue, Shota Kuwahara, Kenji Katayama

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   266   1 - 5   2013.8

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    Molecular dynamics of 4-methoxybenzylidene-4-n-butylaniline (MBBA) in a liquid crystal cell after the perturbation of a UV pulse was observed using the polarization dependent heterodyne transient grating (HD-TG) method. The response of a refractive index change showed different signs depending on the probe polarization, and each response was composed of 4 exponential components. These components were assigned to disordering, 2 types of ordering, and molecular diffusion, judged from the sign of the refractive index change and the dependence on the grating spacing and the pump intensity. The time constants for the disordering and the ordering processes drastically increased for the pump intensity above 0.10 mJ/pulse. To explain the threshold, we proposed that disordering/ordering of domains were observed for the higher pump intensities, while an individual molecule is subject to disordering/ordering for the lower pump intensity. (c) 2013 Elsevier B.V. All rights reserved.

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  • Study of vanadium-modified N/Si co-doped TiO2 in aqueous solution and its photocatalytic activity Reviewed

    Mase, A, Sugita, T, Mori, M, Iwamoto, S, Tokutome, T, Katayama, K, Itabashi, H

    Chemical Engineering Journal   255   440   2013.4

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  • Huge suppression of charge recombination in P3HT-ZnO organic-inorganic hybrid solar cells by locating dyes at the ZnO/P3HT interfaces Reviewed

    Qing Shen, Yuhei Ogomi, Sandeep K. Das, Shyam S. Pandey, Kenji Yoshino, Kenji Katayama, Hisayo Momose, Taro Toyoda, Shuzi Hayase

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   15 ( 34 )   14370 - 14376   2013

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    The charge separation and charge recombination dynamics in P3HT-ZnO and P3HT-dye-ZnO bulk heterojunction organic-inorganic hybrid solar cells (OIHSCs) prepared by a one-pot method were studied using a transient absorption (TA) method, both for optical absorption of P3HT in the visible region and for optical absorption of SQ36 in the NIR region. In the case of P3HT-ZnO, the charge separation was very fast, occurring within 1 ps. On the other hand, high charge recombination between electrons in the surface states and/or the conduction band of ZnO and holes in P3HT was observed. In the case of P3HT-dye-ZnO, we found that the charge recombination could be greatly suppressed by locating the dye at the P3HT/ZnO interfaces while maintaining a fast charge separation rate (a few ps to 10 ps). Our findings provide one methodology for the design of OIHSCs for improving their conversion efficiency, which is to position the dye at the appropriate BHJ interfaces.

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  • Detection of non-absorbing charge dynamics via refractive index change in dye-sensitized solar cells Reviewed

    Shota Kuwahara, Hiroaki Hata, Soichiro Taya, Naotaka Maeda, Qing Shen, Taro Toyoda, Kenji Katayama

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   15 ( 16 )   5975 - 5981   2013

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    The carrier dynamics in dye-sensitized solar cells was investigated by using the transient grating, in addition to the transient absorption method and transient photocurrent method on the order of microseconds to seconds. The signals for the same sample were obtained under a short-circuit condition to compare the carrier dynamics via refractive index change with the transient photocurrent measurement. Optically silent carrier dynamics by transient absorption have been successfully observed via a refractive index change. The corresponding signal components were originated from the charge dynamics at the solid/liquid interface, especially on the liquid side; rearrangement or diffusion motion of charged redox species occurred when the injected electrons were trapped at the TiO2 surface and when the electron-electrolyte recombination occurred at the interface. The assignments were confirmed from the dependence on the viscosity of the solvent and the presence of 4-tert-butyl pyridine. As the viscosity of the solvent increased, the rearrangement and the motion of the charged redox species were delayed. Since the rearrangement dynamics was changed by the presence of 4-tert-butyl pyridine, it affected not only the TiO2 surface but also the redox species close to the interface.

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  • Carrier dynamics in quantum-dot sensitized solar cells measured by transient grating and transient absorption methods Reviewed

    Naotaka Maeda, Hiroaki Hata, Naoya Osada, Qing Shen, Taro Toyoda, Shota Kuwahara, Kenji Katayama

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   15 ( 26 )   11006 - 11013   2013

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    Carrier dynamics in quantum-dot sensitized solar cells (QDSSCs) was clarified by combining the information obtained by the heterodyne transient grating (HD-TG), transient absorption (TA) and transient photocurrent (TP) measurements under the short circuit conditions in the time range from microseconds to seconds. The HD-TG signal is sensitive to the ionic species at the electrode/electrolyte interface, and the electrons in the titanium oxide layer injected from quantum dots (QDs) were monitored by the TA signal, and the photocurrent as a final output was monitored by the TP signal. By using the compensating information, the whole picture of the charge dynamics was obtained in the time region after the initial electron injection from QDs into the titanium oxide layer. In the former part of this paper, the assignment of the responses for each measurement was clarified based on the previous paper on dye sensitized solar cells (S. Kuwahara, et al. Phys. Chem. Chem. Phys., 2013, 15(16), 5975-5981). In the latter part, the effect of the device parameters for actual QDSSCs, such as electrolyte concentrations, and coating times of surface passivation of QDs were investigated.

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  • Ultrafast carrier dynamics in PbS quantum dots Reviewed

    Qing Shen, Kenji Katayama, Tsuguo Sawada, Sojiro Hachiya, Taro Toyoda

    CHEMICAL PHYSICS LETTERS   542   89 - 93   2012.7

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    Ultrafast carrier dynamics in PbS quantum dots (QDs) is characterized using a transient grating technique. In addition to an initial peak, a new peak appears at about 3 ps when the excitation photon energy is greater than 2.7E(g) (E-g: band gap between LUMO and HOMO in the QDs). The first peak is considered to be related to hot carriers and the second one is believed to result from multiple exciton generation (MEG). We found that MEG began in as fast as 200 fs and complete around 3 ps. We succeeded in observing the dynamics of MEG occurrence in PbS QDs. (C) 2012 Elsevier B. V. All rights reserved.

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  • Characterization of Photoexcited Carriers and Thermal Properties of Nanoparticulate TiO2 Film Using Heterodyne Transient Grating Method Reviewed

    Hiroaki Hata, Kenji Katayama, Qing Shen, Taro Toyoda

    JAPANESE JOURNAL OF APPLIED PHYSICS   51 ( 4 )   2012.4

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    Diffusion of photoexcited carriers and the subsequent thermal diffusion by photoexcitation of a nanoparticulate TiO2 thin film were observed by the heterodyne transient grating (HD-TG) method. The observed HD-TG signal showed that the photoexcited carriers were generated inhomogeneously in the depth direction and they diffused both in the depth and parallel directions of the film. The diffusion processes were analyzed using a two-dimensional diffusion model. The thermal profile generated by the relaxation of the photoexcited carriers was treated by the same model. It was found that the effective diffusivities of the photoexcited carriers and heat decreased as the size of the nanoparticles in the film increased. It is suggested that the transport properties of the photoexcited carriers and heat are dominated by the inter-particulate resistance. (C) 2012 The Japan Society of Applied Physics

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  • Multiple electron injection dynamics in linearly-linked two dye co-sensitized nanocrystalline metal oxide electrodes for dye-sensitized solar cells Reviewed

    Qing Shen, Yuhei Ogomi, Byung-wook Park, Takafumi Inoue, Shyam S. Pandey, Akari Miyamoto, Shinsuke Fujita, Kenji Katayama, Taro Toyoda, Shuzi Hayase

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   14 ( 13 )   4605 - 4613   2012

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    Understanding the electron transfer dynamics at the interface between dye sensitizer and semiconductor nanoparticle is very important for both a fundamental study and development of dye-sensitized solar cells (DSCs), which are a potential candidate for next generation solar cells. In this study, we have characterized the ultrafast photoexcited electron dynamics in a newly produced linearly-linked two dye co-sensitized solar cell using both a transient absorption (TA) and an improved transient grating (TG) technique, in which tin(IV) 2,11,20,29-tetra-tert-butyl-2,3-naphthalocyanine (NcSn) and cis-diisothiocyanato-bis(2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II) bis(tetrabutylammonium) (N719) are molecularly and linearly linked and are bonded to the surface of a nanocrystalline tin dioxide (SnO2) electrode by a metal-O-metal linkage (i.e. SnO2-NcSn-N719). By comparing the TA and TG kinetics of NcSn, N719, and hybrid NcSn-N719 molecules adsorbed onto both of the SnO2 and zirconium dioxide (ZrO2) nanocrystalline films, the forward and backward electron transfer dynamics in SnO2-NcSn-N719 were clarified. We found that there are two pathways for electron injection from the linearly-linked two dye molecules (NcSn-N719) to SnO2. The first is a stepwise electron injection, in which photoexcited electrons first transfer from N719 to NcSn with a transfer time of 0.95 ps and then transfer from NcSn to the conduction band (CB) of SnO2 with two timescales of 1.6 ps and 4.2 ps. The second is direct photoexcited electron transfer from N719 to the CB of SnO2 with a timescale of 20-30 ps. On the other hand, back electron transfer from SnO2 to NcSn is on a timescale of about 2 ns, which is about three orders of magnitude slower compared to the forward electron transfer from NcSn to SnO2. The back electron transfer from NcSn to N719 is on a timescale of about 40 ps, which is about one order slower compared to the forward electron transfer from N719 to NcSn. These results demonstrate that photoexcited electrons can be effectively injected into SnO2 from both of the N719 and NcSn dyes.

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  • Separation of ultrafast photoexcited electron and hole dynamics in CdSe quantum dots adsorbed onto nanostructured TiO2 films Reviewed

    Qing Shen, Yasumasa Ayuzawa, Kenji Katayama, Tsuguo Sawada, Taro Toyoda

    APPLIED PHYSICS LETTERS   97 ( 26 )   2010.12

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    The ultrafast photoexcited electron and hole dynamics of CdSe quantum dots (QDs) deposited onto nanostructured TiO2 films were studied using an improved transient grating (TG) technique. By comparing the TG responses measured in air and in a Na2S solution (holeacceptor), we succeeded in separating the dynamic characteristics of photoexcited electrons and holes in the CdSe QDs. We found that charge separation in the CdSe QDs occurred over a very fast time scale from a few hundreds of femtoseconds in the Na2S solution via hole transfer to S2- ions to a few picoseconds in air via hole trapping. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3533374]

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  • Comparative study of by near-field heterodyne transient grating and continuously variable spatial frequency transient grating methods for measurements of terahertz reflection responses Reviewed

    H. Inoue, K. Katayama, Q. Shen, T. Toyoda, K. A. Nelson

    15TH INTERNATIONAL CONFERENCE ON PHOTOACOUSTIC AND PHOTOTHERMAL PHENOMENA (ICPPP15)   214   012123   2010

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    We measured terahertz reflection responses utilizing a propagating phonon polariton wave, which was generated and detected by two different methods: the near-field heterodyne transient grating and the continuously variable spatial frequency transient grating method. The obtained results were compared for the purpose of clarifying which of both methods is better for measurements of terahertz reflection responses. The phonon polariton wave is propagated and reflected at a ferroelectric crystal edge. From the viewpoint of the separation between the excited and reflected phonon polariton waves, the latter method is better for measurements of reflection responses.

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  • Electron dynamics in GaN wafers with an inhomogeneous distribution of defects in the depth direction Reviewed

    Yuji Ohashi, Kenji Katayama, Qing Shen, Taro Toyoda

    JOURNAL OF APPLIED PHYSICS   106 ( 6 )   2009.9

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    The dynamics of photoexcited electrons in a GaN wafer with an inhomogeneous dislocation density distribution in the depth direction was measured by the near-field heterodyne transient grating method. We investigated the dependence of the interfaces with different dislocation densities, the dependence on the pump wavelength for a sample with a decaying distribution of dislocation density, which gives information on the depth dependence on the carrier dynamics. In the latter experiment, the observed depth region was continuously changed by tuning the wavelength around the band gap of GaN. The responses of the electron dynamics can be fitted with the sum of two exponential decays for all the experiments and only the slower component decayed faster as the dislocation density increased. It was concluded that the faster component corresponded to the trap process of electrons by deep states due to inherent defects in the GaN wafer and the slower component corresponded to the recombination of the trapped electrons at the defect states by dislocation defects. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3197281]

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  • Terahertz reflection response measurement using a phonon polariton wave Reviewed

    Hayato Inoue, Kenji Katayama, Qing Shen, Taro Toyoda, Keith A. Nelson

    JOURNAL OF APPLIED PHYSICS   105 ( 5 )   2009.3

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    We developed a new technique for the measurement of terahertz reflection responses utilizing a propagating phonon polariton wave. Frequency tunable phonon polariton waves were generated by the recently developed continuously variable spatial frequency transient grating method [K. Katayama, H. Inoue, H. Sugiya, Q. Shen, T. Taro, and K. A. Nelson, Appl. Phys. Lett. 92, 031906 (2008)]. The phonon polariton wave traveled in a ferroelectric crystal in an in-plane direction with an inclined angle of 26 degrees, and the wave reflected at the crystal edge where a sample was positioned. The reflected polariton wave was detected by the same method as that used for the generation of the polariton waves. By comparing the reflection intensities in the presence and absence of the sample, reflectivity of the polariton wave was calculated, and the refractive index and absorption in the terahertz region were obtained.

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  • Photochemical reaction dynamics measured using the near-field heterodyne transient grating method

    Mitsuhide Okuda, Kenji Katayama

    Journal of Physical Chemistry A   112 ( 20 )   4545 - 4549   2008.4

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  • Characterization of electron transfer from CdSe quantum dots to nanostructured TiO2 electrode using a near-field heterodyne transient grating technique

    Qing Shen, Kenji Katayama, Tsuguo Sawada, Taro Toyoda

    Thin Solid Films   516 ( 17 )   5927 - 5930   2008.4

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  • Hybrid flow velocimeter in a microchannel for transparent and turbid liquid using a transmission grating

    Mitsumasa Kuraya, Kenji Katayama

    Review of Scientific Instruments   79   2008.4

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  • Development of heterodyne detection of dynamic light scattering enhanced by the talbot effect for the size measurement of nanoparticles

    Hiroko Nomura, Kenji Katayam

    ANALYTICAL SCIENCES   24 ( 4 )   459 - 462   2008.4

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    A new type of dynamic light scattering method for the size measurement of nanoparticles was developed using a transmission grating. A sample cell was located behind the grating, and light was incident from the grating side. The scattered light by a solution with nanopariticles was mixed with diffracted light by the grating, and the mixed signal was detected; namely, the diffracted light was used as reference light for heterodyne detection. It was confirmed that the SIN ratio of the autocorrelation curve was 26-times improved by heterodyne detection. Furthermore, the SIN ratio was improved by setting the sample cell at the sample grating distance where the electromagnetic field is maximum due to the Talbot effect. Size measurements for several kinds of nanoparticles were demonstrated by this new method.

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  • Detection of active oxygen species dynamics in TiO(2) sol solutions using single-shot near-field heterodyne transient grating method

    Toru Tsuruta, Mitsuhide Okuda, Kenji Katayama

    CHEMICAL PHYSICS LETTERS   456 ( 1-3 )   47 - 50   2008.4

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    Active oxygen species generated by photoexcitation of TiO(2) sol solutions were directly observed by the single-shot near-field heterodyne transient grating method. Two kinds of dynamics due to chemical species were observed and their lifetimes and diffusion coefficients were determined. From the dependence of the quantity of dissolved oxygen, it was confirmed that one of the species was generated from dissolved oxygen, such as a superoxide anion. Furthermore, this species was found to have a very small diffusion coefficient compared with other molecules with similar molecular weight, thereby suggesting that it was adsorbed onto TiO(2) particles. (C) 2008 Elsevier B.V. All rights reserved.

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  • Formation dynamics of gold nanoparticles measured by single-shot near-field heterodyne transient grating method

    Yuta Nakazato, Mitsuhide Okuda, Kenji Katayama

    Chemical Physics Letters   457 ( 1-3 )   313 - 320   2008.4

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  • Hybrid flow velocimeter measurements of transparent and turbid liquids in a microchannel using a transmission grating Reviewed

    Mitsumasa Kuraya, Kenji Katayama, Takehiko Kitamori

    REVIEW OF SCIENTIFIC INSTRUMENTS   79 ( 2 )   2008.2

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    A Doppler velocimeter with a transmission grating was developed for flow rate measurements inside a microchannel. This velocimeter has the same optical setup as a recently developed flow velocimeter for transparent liquids, in which two beams (pump and probe) optically coupled to a fiber were used. Although the principle of the flow velocity measurement was quite different between the two methods, the optical setups used were almost similar; the differences are that only the probe beam is used and fast Fourier transform analysis is utilized for the signal processing in the new technique. This development offers hybrid flow velocimeter for both transparent and turbid liquids. (C) 2008 American Institute of Physics.

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  • Generation and detection of tunable phonon polaritons using a single transmission grating

    Kenji Katayama, Hayato Inoue, Hisashi Sugiya, Qing Shen, Taro Toyoda, Keith A. Nelson

    Applied Physics Letters   92 ( 3 )   2008

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    Frequency tunable phonon polariton waves were generated and detected using an original optical configuration of the transient grating method. In this technique, the excitation beam was shone onto a transmission grating after being transmitted through a lens, and a lithium niobate wafer located at a defocus position of the lens was irradiated by an expanded or reduced image of the transmission grating, causing excitation of phonon polaritons. Because the magnification of the light intensity pattern can be controlled by the sample-grating distance, the wavelength of the phonon polaritons, which is equal to the optical fringe spacing, can be continuously varied. © 2008 American Institute of Physics.

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  • Optical absorption, photosensitization, and ultrafast carrier dynamic investigations of CdSe quantum dots grafted onto nanostructured SnO2 electrode and fluorine-doped tin oxide (FTO) glass

    Qing Shen, Makoto Yanai, Kenji Katayama, Tsuguo Sawada, Taro Toyoda

    CHEMICAL PHYSICS LETTERS   442 ( 1-3 )   89 - 96   2007.7

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    CdSe quantum dots (QDs) are adsorbed onto nanostructured SnO2 and planar FTO electrodes by a chemical adsorption technique. Optical absorption and the incident-photon-to-current conversion efficiency (IPCE) are studied by using photoacoustic and photoelectrochemical methods. The growth rate of the CdSe QDs depends on the morphology of the substrate. Larger IPCE peak values and larger integrated area for the IPCE spectra are obtained for the nanostructured SnO2 electrodes. The ultrafast carrier dynamics of the CdSe QDs are studied using a transient grating technique. It is found that the electron relaxation of the CdSe QDs depends strongly on the morphology of the substrate. (C) 2007 Elsevier B.V. All rights reserved.

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  • Optical absorption and ultrafast carrier dynamics characterization of CdSe quantum dots deposited on different morphologies of nanostructured TiO2 films

    Lina J. Diguna, Qing Shen, Akira Sato, Kenji Katayama, Tsuguo Sawada, Taro Toyoda

    Materials Science and Engineering C   27 ( 5 )   1514 - 1520   2007.6

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  • Flow velocity detector in a microchip based on a photothermally induced grating

    Kenji Katayama, Yoshikuni Kikutani, Takehiko Kitamori

    ANALYTICAL SCIENCES   23 ( 6 )   639 - 643   2007.6

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    A new photothermal technique was developed for measuring the flow velocity and making solute concentration measurements in a microchip by using the same optical and instrumental setup. Collinear pump and probe light were irradiated onto a microchip surface on which a grating pattern was fabricated. The pump light induced a temperature change with the grating pattern in a microchannel, and a refractive index change due to a subsequent temperature rise was monitored by a heterodyned diffraction signal of the probe light. The flow velocity and concentration were obtained by monitoring the motion and intensity change of the thermally induced grating, respectively. The dynamic range of the flow velocity measurement was 0.17-670 mm/s, which is sufficient for covering most chemical applications of a microchip. The detection limit of the concentration measurement was 2 x 10(-6) M for a rhodamine B solution.

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  • Selective detection of real and imaginary parts of refractive index change in solutions induced by photoexcitation using near-field heterodyne transient grating method

    Mitsuhide Okuda, Kenji Katayama

    Chemical Physics Letters   443 ( 1-3 )   158 - 162   2007.4

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  • Ultrafast charge transfer in surface-enhanced Raman scattering (SERS) processes using transient reflecting grating (TRG) spectroscopy

    Kohei Shibamoto, Kenji Katayama, Tsuguo Sawada

    CHEMICAL PHYSICS LETTERS   433 ( 4-6 )   385 - 389   2007.1

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    Ultrafast dynamics was investigated for photo-excited electrons between a SERS-active gold substrate and several kinds of adsorbed dyes by using TRG spectroscopy. A charge transfer (CT) within 200 fs between them was observed for a SERS-active sample and the number of CT electrons had a strong correlation to both the relative adsorption energy states (AESs) of dyes and the enhancement factors of their SERS band. To increase the number of CT electrons, the AESs should be closer to the excited energy state of gold. A larger number of CT electrons are considered to make the enhancement of SERS band larger. (c) 2006 Elsevier B.V. All rights reserved.

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  • Preparation of highly concentrated aqueous solution of sodium borate

    Isao Tsuyumoto, Tomokazu Oshio, Kenji Katayama

    INORGANIC CHEMISTRY COMMUNICATIONS   10 ( 1 )   20 - 22   2007.1

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    A highly concentrated aqueous solution of sodium borate with 5.24 mol/kg of boron was prepared at 20 degrees C by adjusting the Na/B ratio at 0.22 (pH 6.9). This is more than twice more concentrated than the most soluble known borate solution (Na2O center dot B2O3 center dot 8H(2)O, 2.49 mol/kg at 20 degrees C). Analysis using the Raman spectroscopy and the APCI/MS (atmospheric pressure chemical ionization/mass spectrometry) suggested the formation of polyborate ions such as B9O10(OH)(9)(2-), B10O12(OH)(8)(2-), B11O14(OH)(7)(2-), B12O16(OH)(6)(2-). (c) 2006 Elsevier B.V. All rights reserved.

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  • Phonon polariton generation and detection using near-field heterodyne transient grating method

    Kenji Katayama, Qing Shen, Taro Toyoda, Keith A. Nelson

    Applied Physics Letters   90 ( 17 )   171117 - 171119   2007

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    A technique for the generation and detection of phonon polariton was developed based on the near-field heterodyne transient grating method. It features a compact and simple optical setup and easy wavelength tuning ability of the phonon polariton. The wavelength was tuned by changing the grating spacing of a transmission grating positioned in front of a sample, and this was performed by sliding a glass plate with transmission gratings with many different grating spacings along the glass plate surface. © 2007 American Institute of Physics.

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  • In situ microfluidic flow rate measurement based on near-field heterodyne grating method

    Kenji Katayama, Hisato Uchimura, Hitomi Sakakibara, Yoshikuni Kikutani, Takehiko Kitamori

    Review of Scientific Instruments   78 ( 8 )   083101 - 083107   2007

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    The near-field heterodyne grating (NF-HDG) method was applied to flow rate measurements in a microtube. The NF-HDG method is a newly developed optical technique based on photothermal effects. In this technique, pump light is shone on a transmission grating in front of a fluid channel and the inside liquid is heated with a pattern of the grating due to the Talbot effect. Another probe light is similarly shone on the same place as the pump light, and the diffraction by the transmission grating (reference) and the diffraction by the temporally generated thermal grating inside the fluid channel (signal) are mixed and detected (heterodyne detection). Theoretical analysis reveals that the dependence of the heterodyne signal intensity on the flow rate originates from the change in the heterodyne phase difference between the signal and reference, and the experimentally obtained calibration curves can be fitted with the theoretically predicted function. Furthermore, the optical setup was optimized based on the theoretical analysis of the Talbot effect. Flow rates of the order of nl/min were quantitatively measured, and the detection limit of the flow rate was 17 nlmin. © 2007 American Institute of Physics.

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  • Characterization of carrier dynamics in semiconductor nanomaterials using near-field heterodyne transient grating method Reviewed

    Q. Shen, K. Katayama, T. Sawada, T. Toyoda

    MICROPROCESSES AND NANOTECHNOLOGY 2007, DIGEST OF PAPERS   34 - +   2007

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  • Carrier dynamics in porous silicon studied with a near-field heterodyne transient grating method

    Masahiro Yamaguchi, Kenji Katayama, Qing Shen, Taro Toyoda, Tsuguo Sawada

    CHEMICAL PHYSICS LETTERS   427 ( 1-3 )   192 - 196   2006.8

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    The dynamics of excited carriers in porous silicon were investigated using the near-field heterodyne transient grating method, and the fundamental processes related to light emission were determined. The processes include trapping to surface states and two-body recombination of excited carriers, with trapping being the dominant source of light emission. Since nonlinear processes, namely two-body recombination, are included, it is necessary to measure the pump intensity dependence of the transient responses and to analyze them with a nonlinear differential equation in order to obtain accurate decay times. (c) 2006 Elsevier B.V. All rights reserved.

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  • Optical absorption, photoelectrochemical, and ultrafast carrier dynamic investigations of TiO2 electrodes composed of nanotubes and nanowires sensitized with CdSe quantum dots

    Qing Shen, Kenji Katayama, Tsuguo Sawada, Masahiro Yamaguchi, Taro Toyoda

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 6B )   5569 - 5574   2006.6

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    TiO2 electrodes composed of nanotubes and nanowires are prepared from TiO2 gels using a surfactant-assisted self-assembly method reported earlier. CdSe quantum dots (QDs) are adsorbed onto the. TiO2 electrodes by chemical deposition (CD). Their average size increases from 4 to 6nm with increasing deposition time from 3 to 82h. The optical absorption and incident photon-to-current conversion efficiency (IPCE) of the electrodes are studied by photoacoustic (PA) and plIiotoelectrochemical (PEC) methods. The photosensitization of the TiO2 electrodes by CdSe QDs is demonstrated by both PA and IPCE spectra. The ultrafast carrier dynamics of the CdSe-sensitized TiO2 electrodes composed of nanotubes and nanowires is studied using a lens-free heterodyne detection transient grating (LF-HD-TG) technique.,Fast and slow decay processes with lifetimes of about 3 ps and 60-130 ps, respectively, are observed.

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  • 「実験科学講座 第5版 分光(Ⅰ)(全640頁)」のうち 9. その他の分光法 9.1 「光音響分光法(pp.577-586)」

    編者 田原太平, 澤田嗣郎, 片山建二

    (株)丸善   2005.10

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  • Formation of a ripple pattern at a water/silicon interface using an oscillating bubble Reviewed

    H Yonekubo, K Katayama, T Sawada

    APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING   81 ( 4 )   843 - 846   2005.9

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    A single femtosecond laser pulse was irradiated at a water/silicon interface, and the processed surface was investigated. Rings surrounded by ripples were found within the irradiated spot. The diameter of the rings ranged from 500 nm to 10 mu m. It is proposed that acoustic waves, caused by the oscillating motion of bubbles near the water/silicon interface, deformed the melting silicon surface. In the present work, a pulse (pulse width: 150 fs) was tightly focused in water to induce optical breakdown, and a bubble was generated at an arbitrary spot. When the power density was below the ablation threshold and above the melting threshold at the silicon surface and set above the breakdown threshold at the focus in water, a pattern was generated at a specific place and with a specific size.

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  • Study of ultrafast carrier dynamics of nanostructured TiO2 films with and without CdSe quantum dot deposition using lens-free heterodyne detection transient grating technique Reviewed

    Q Shen, K Katayama, M Yamaguchi, T Sawada, T Toyoda

    THIN SOLID FILMS   486 ( 1-2 )   15 - 19   2005.8

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    Ultrafast carrier dynamics of nanostructured TiO2 films with and without Use quantum dot (QD) deposition were studied using a lensfree heterodyne detection transient grating (LF-HD-TG) technique. The natiostructured TiO2 films were prepared with anatase TiO2 nanoparticles with an average diameter of 27 nm. Use quantum dots with an average size of 5 nm were adsorbed onto the TiO2 films by a chemical deposition (CD) technique. The relaxation processes of the photoexcited electrons and holes can be detected separately using the LF-HD-TG technique. For the TiO2 film without CdSe deposition, it was found that the photoexcited holes relaxed within 2 ps. For the Use QD deposited nanostructured TiO2 film, two decay processes with time constants of 2 ps (tau(1)) and 16 PS (tau(2)) were detected. The fast decay process was attributed to photoexcited hole relaxation due to trapping in Use QDs. The slow decay process mainly reflected photoexcited electron transfer from Use QDs to TiO2. (c) 2005 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.tsf.2004.11.238

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  • Lens-free heterodyne transient grating technique Reviewed

    K Katayama, Q Shen, T Toyoda, M Yamaguchi, T Sawada

    JOURNAL DE PHYSIQUE IV   125   349 - 353   2005.6

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    Recently developed lens-free heterodyne transient grating technique was applied to samples with rough surfaces on the order of several microns and photo-induced transient responses were successfully obtained on the temporal order of picoseconds. It was shown that the limitation of the sample roughness considerably reduced, compared with other conventional ultrafast methods. Theoretically the sample roughness was allowed on the order of 100 microns under our experimental condition, while it is on the order of several hundreds nanometers using a transient grating method.

    DOI: 10.1051/jp4:2005125082

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  • Photoexcited hole dynamics in TiO2 nano crystalline films characterized using a lens-free heterodyne detection transient grating techniqu

    Chem. Phys. Lett.   419   464 - 468   2005.2

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  • Carrier dynamics of anatase and rutile TiO2 nanostructured electrodes adsorbed with CdSe quantum dots Reviewed

    Qing Shen, Yoki Kumagai, Kenji Katayama, Masahiro Yamaguchi, Tsuguo Sawada, Taro Toyoda

    IQEC, International Quantum Electronics Conference Proceedings   2005   781 - 782   2005

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    Ultrafast carrier dynamics of anatase and rutile TiO2 nanostructured electrodes deposited with CdSe quantum dots (QDs) are studied using lens-free heterodyne detection transient grating (LF-HD-TG) technique. We find that the relaxation time of the photoexcited holes is as long as a few hundreds ps for rutile TiO2, but is smaller than 2 ps for anatase TiO2. Two decay processes with time scales of 2 ps (τ1) and a few tens ps or hundreds ps (τ2) are observed for CdSe QDs. The fast decay process is considered as photoexcited hole relaxation owing to trapping by the surface states of CdSe QDs. While the slow decay process reflects photoexcited electron relaxation processes, and mainly electron transfer from CdSe QDs to TiO2. We find that relaxation time of electrons (τ2) depends greatly on the crystal structure of TiO2.

    DOI: 10.1109/IQEC.2005.1561002

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  • Photoexcited carrier dynamic characterization of TiO2 electrodes composed of different size mixture of nanoparticles sensitized with CdSe quantum dots Reviewed

    Taro Toyoda, Yuki Kumagai, Qing Shen, Masahiro Yamaguchi, Tsuguo Sawada, Kenji Katayama

    IQEC, International Quantum Electronics Conference Proceedings   2005   253 - 254   2005

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    We investigate the effect of different size mixture of TiO2 nanoparticles (15 and 27 nm) in anatase-type electrodes sensitized with CdSe quantum dots on excited carrier dynamics. The decay time of excited electrons in CdSe quantum dots decreases with the increase of 27 nm nanoparticles mixture.

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  • 「先端の分析法-理工学からナノ・バイオまで(全1000頁)」のうち第2章 物理的検出法 第1節 一般分光法 5.「光熱変換分光法(pp.111-117頁)」

    監修 梅澤喜夫, 澤田嗣郎, 寺部茂, 片山建二, 澤田嗣郎

    (株)エヌ・ティー・エス   2004.12

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  • 「新訂版 表面科学の基礎と応用(全1592頁)」のうち 第1編 基礎編 第10章 固液界面の基礎 第4節 「固液界面の計測」

    編集者代表, 岩澤康裕, 片山建二

    (株)エヌ・ティー・エス   343352   2004.6

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  • Dose dependence of carrier and heat dynamics at an ion-implanted silicon surface measured using lens-free heterodyne transient grating method Reviewed

    K Katayama, M Yamaguchi, T Sawada

    JOURNAL OF APPLIED PHYSICS   94 ( 8 )   4904 - 4907   2003.10

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    The lens-free heterodyne transient grating method was shown to reveal the dynamics of photoexcited carriers and heat on the surface region of an ion-implanted silicon in the dose range of 10(11)-10(15) cm(-2). In addition to the fact that the detection limit of the dose was superior to that for conventional methods, several physical properties of the carrier and heat can be obtained by analyzing transient responses. Theoretical analysis provided the lifetime of carriers and thermal diffusion coefficients in the ion-implanted surface region. (C) 2003 American Institute of Physics.

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  • Lens-free heterodyne transient grating method for dynamics measurement of photoexcited species in liquid Reviewed

    M Yamaguchi, K Katayama, T Sawada

    CHEMICAL PHYSICS LETTERS   377 ( 5-6 )   589 - 594   2003.8

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    A recently developed lens-free heterodyne transient grating method was applied for the measurement of ultrafast photoexcited dynamics of several kinds of dye molecules in aqueous solutions. The principle of the lens-free heterodyne transient grating method was clarified in detail, especially for thick samples, such as liquid and semi-transparent solid samples. The ultrafast dynamics of malachite green and methyl orange molecules in aqueous solutions was successfully monitored, and the obtained time constants agreed with those in other reports. (C) 2003 Elsevier B.V. All rights reserved.

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  • Formation of ring patterns surrounded by ripples by single-shot laser irradiation with ultrashort pulse width at the solid/liquid interface Reviewed

    Kenji Katayama, Hideaki Yonekubo, Tsuguo Sawada

    Applied Physics Letters   82 ( 24 )   4244 - 4246   2003.6

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    The formation of ring patterns by single-shot laser irradiation at the solid/liquid interface was investigated. The processed surface was found to have many ring patterns surrounded by sinusoidal patterns within the irradiated spot. The diameter of the rings were found to be from 500 nm to 10 μm.

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  • Lens-free heterodyne detection of transient grating Reviewed

    Kenji Katayama, Masahiro Yamaguchi, Tsuguo Sawada

    Applied Physics Letters   82 ( 17 )   2775 - 2777   2003.6

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  • Fundamental processes of surface enhanced Raman scattering detected by transient reflecting grating spectroscopy Reviewed

    K Shibamoto, K Katayama, T Sawada

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   158 ( 2-3 )   105 - 110   2003.6

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    Ultrafast charge transfer (CT) between gold and crystal violet (CV) molecules in relation with the surface enhanced Raman scattering (SERS) activation was investigated using the transient reflecting grating (TRG) spectroscopic method. A charge transfer between gold and crystal violet was observed only for the SERS-active substrate and it occurred within 200 fs. Since the adsorbed dyes had electronic overlap with the metal substrate at the point of central carbon, considering the difference of the Raman spectra between adsorbed and free dyes, it was suggested that the charge transfer occurred through the central carbon of crystal violet. Furthermore, it was shown that the surface morphology of the substrates is in close correlation with the charge transfer process from its dependence on the preparation method of substrates. (C) 2003 Elsevier Science B.V. All rights reserved.

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  • Fundamental processes of surface enhanced Raman scattering detected with transient reflecting grating spectroscopy Reviewed

    K Shibamoto, K Katayama, M Fujinami, T Sawada

    REVIEW OF SCIENTIFIC INSTRUMENTS   74 ( 1 )   910 - 912   2003.1

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    We investigated ultrafast photoexcited electrons dynamics in relation to the surface enhanced Raman scattering (SERS) effect, using the transient reflecting grating spectroscopy method. We observed that only SERS-active samples had transfer of photoexcited electrons from a metal surface to adsorbed molecules within 200 fs followed by return of these charge transferred electrons to the metal within several picoseconds. By analyzing charge transfer (CT) processes, we were able to identify the main influential factors of the adsorption state, stay time at adsorbed molecules, and quantity of CT carriers. That these obtained factors had correlations to each other may lead to clarification of the CT processes within several picoseconds with regard to the SERS enhancement mechanism. (C) 2003 American Institute of Physics.

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  • Transient reflecting grating spectroscopy for defect analysis in surface region of semiconductors Reviewed

    K Katayama, H Donen, T Sawada

    REVIEW OF SCIENTIFIC INSTRUMENTS   74 ( 1 )   902 - 904   2003.1

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    Ultrafast transient reflecting grating (TRG) spectroscopy was utilized for defect analysis in the surface region of ion-implanted silicon for the implantation range from 10(11) to 10(15) cm(-2). To deduce signals due to trapped carriers at defect states, the TRG spectra at the delay time of 30 ps were measured because ultrafast carrier dynamics such as many-body recombination had finished before the delay time. According to the dose quantity, the peak of the interband transition was affected and also defect-related transitions emerged. Using this technique, implantation damage can be detected for samples with their dose larger than 10(12) cm(-2). It was proposed that TRG spectroscopy can be used as a novel analytical method for characterizing defects in the surface region of semiconductors. (C) 2003 American Institute of Physics.

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  • Laser processing at solid-liquid interfaces using femtosecond pulse laser sources

    K Katayama, H Yonekubo, T Sawada

    FOURTH INTERNATIONAL SYMPOSIUM ON LASER PRECISION MICROFABRICATION   5063   367 - 369   2003

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    Laser processing using light sources with ultrashort pulses was applied to solid/liquid interfaces. A single-shot 200-fs pulse light was simply focused and irradiated or two pulses were interfered and irradiated at a water or electrolyte solution/silicon interface. From the measured AFM images on the processed silicon surfaces, several features were revealed, which were characteristic of the laser processing at the solid/liquid interface. First, ring patterns surrounded by sinusoidal patterns like ripples were found within the irradiated spot. Secondly, the processed depth was reduced by coexisting electrolyte in water. Thirdly, there were less residual aggregates or debris.

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  • Ultrafast nonlinear response of high density carriers at silicon surface detected by simultaneous measurements of transient reflecting first and second order diffractions Reviewed

    K Katayama, Y Inagaki, T Sawada

    JOURNAL OF APPLIED PHYSICS   92 ( 9 )   5233 - 5237   2002.11

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    The simultaneous detections of transient reflectivity (TR), transient reflecting first and second order diffraction signals, at a silicon surface revealed that each signal reflected different physical processes of carrier dynamics under a high pump power of 5 mJ/cm(2). It was shown that the second order diffraction could detect a refractive index change which was not linearly dependent on the excited carrier density, and it was suggested that the nonlinearity was caused by many-body interactions among carriers at the band-edge states. The dynamics observed with the second order diffraction corresponded to the recombination of the band-edge carriers. Analysis of the first and second order diffractions in combination with the recently developed spectroscopic detection provided selective information on the ultrafast carrier and heat dynamics for a silicon surface, that is, carrier-phonon scattering, recombination of carriers, heat generation, and diffusion. Additionally, it was shown the TR might allow observation of mixed physical processes detected by the first and second order diffractions and it was suggested that deducing exact physical processes only from the TR signal, especially under high pump power conditions, was difficult. (C) 2002 American Institute of Physics.

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  • Analysis of transient reflecting grating spectrum for silicon surface Reviewed

    Kenji Katayama, Daisuke Taniguchi, Tsuguo Sawada

    Analytical Sciences   17   i87 - 90   2002.8

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  • Transient reflecting grating spectroscopy for defect analysis of surface region of semiconductors Reviewed

    H Donen, K Katayama, T Sawada

    JOURNAL OF APPLIED PHYSICS   92 ( 3 )   1367 - 1371   2002.8

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    Ultrafast transient reflecting grating (TRG) spectroscopy was applied to investigate the influence of various defect states on ultrafast carrier dynamics of up to 3 ps duration in an ion-implanted silicon surface region. The TRG spectra revealed the energy-state distribution of two kinds of defect states, and it was observed that photoexcited carriers were trapped in each state depending on annealing time. It was proposed that TRG spectroscopy can be used as an analytical method for characterizing defects in the surface region of semicondcutors. (C) 2002 American Institute of Physics.

    DOI: 10.1063/1.1492860

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  • Fundamental processes of surface enhanced Raman scattering detected with transient reflecting grating spectroscopy Reviewed

    Kohei Shibamoto, Kenji Katayama, Masanori Fujinami, Tsuguo Sawada

    Analytical Sciences   17   91 - 94   2002.8

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  • Ultrafast dynamics at a silicon surface detected with femtosecond transient reflecting grating spectroscopy Reviewed

    K Katayama, K Sugai, Y Inagaki, T Sawada

    JOURNAL OF APPLIED PHYSICS   91 ( 3 )   1074 - 1080   2002.2

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    The recently developed spectroscopic transient reflecting grating technique with a time resolution of 200 fs was applied to a silicon surface under the pump intensity of more than 1 mJ/cm(2). This method provides information on excited free carrier dynamics and subsequent heat generation and diffusion selectively based on appropriate choice of probe wavelength. With regard to the thermal component, the temperature at the surface increased within several picoseconds and then decayed after about 300 ps. As the pump intensity was increased, the maximum temperature rise showed a nonlinear dependence on it, and also the temperature rise time became faster. The results led to the conclusion that the carrier dynamics causing a temperature rise at a silicon surface is dominated mainly by Auger recombination, not by the decay to a band edge under the high carrier density conditions. (C) 2002 American Institute of Physics.

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  • Evaluation of thermal and elastic properties for solid surfaces using transient reflecting grating method

    Kenji Katayama, Qing Shen, Akira Harata, Tsuguo Sawada

    Proceedings of 10th International Congress of Fracture   100930OR   2001.12

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  • Recent advances of photothermal spectroscopy

    Tsuguo Sawada, Kenji Katayama

    Proceedings of 10th International Congress of Fracture   100927OR   2001.12

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  • Influence of annealing process on ultrafast carrier dynamics for ion-implanted silicon surface

    Hisrishi Donen, Yohei Inagaki, Kenji Katayama, Tsuguo Sawada

    Proceedings of 10th International Congress of Fracture   100931OR   2001.12

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  • Direct observation of ultrafast charge transfer in relation to the surface enhanced Raman scattering activation detected by transient reflecting grating spectroscopy Reviewed

    K Katayama, K Shibamoto, T Sawada

    CHEMICAL PHYSICS LETTERS   345 ( 3-4 )   265 - 271   2001.9

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    Ultrafast charge transfer related to the surface enhanced Raman scattering (SERS) activation was found using the transient reflecting grating spectroscopic method. Two kinds of vapor-deposited gold films were prepared as SERS substrates. One of them induced the SERS effect (SERS active substrate), while the other did not (SERS inactive substrate). A charge transfer between gold and pyridine was observed only for the former and it occurred within 200 fs. Further, it was suggested that the surface roughness of the substrate not only induced electromagnetic enhancement, but also generated new adsorption sites that made a charge transfer occur easily. (C) 2001 Published by Elsevier Science B.V.

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  • Ultrafast processes at a silicon surface detected with time-resolved transient reflecting spectroscopy

    Kenji Katayama, Yohei Inagaki, Tsuguo Sawada

    Proceedings of 12th International Conference on Thermal Engineering and Thermogrammetry   61 - 64   2001.6

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  • Ultrafast dynamics of CdSxSe1-x nanocrystals doped in glasses studied by ultrafast transient lensing effect Reviewed

    Q Shen, T Toyoda, Y Hirose, K Katayama, H Yui, M Fujinami, T Sawada, A Harata

    ANALYTICAL SCIENCES   17   S241 - S244   2001

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    Ultrafast dynamics of CdSxSe1-x (x=0.26) nanocrystals doped in glasses was studied using a femtosecond ultrafast transient lensing (UTL) technique. Three kinds of samples with different average diameters (5.3 nm, 6.5 nm and 9.4 nm, respectively) of CdSxSe1-x(x=0.26) nanocrystals were measured after photodarkened by irradiation of a pulsed laser light with a peak power density of 3 GW/cm(2) for 2 minutes. The UTL signals showed tri-exponential behaviors and three decay times were estimated to be about 1ps, 9 ps and > 300 ps. The three decay components were considered to be attributed to the direct recombination and trapping by some trapping states from the excited states, and subsequently radiative and nonradiative recombination processes through two kinds of trapping states at the nanocrystal-glass interfaces for the photo-excited carriers. It was found that as the averaged size of CdSxSe1-x (x=0.26) nanocrystals in the glasses decreased, the relative intensity of the 3rd component increased while that of the 2nd component decreased.

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  • Direct measurement of non-equilibrium carrier diffusion at a Si surface Reviewed

    Y Inagaki, K Katayama, M Fujinami, T Sawada

    ANALYTICAL SCIENCES   17   S251 - S254   2001

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    We have developed an ultrafast carrier dynamics measurement method which provides both a transient reflecting grating signal and a transient reflectivity signal. The method was used to measure the carrier dynamics at a silicon surface in the carrier density range of 1.6-3.0 x 10(20) cm(-3), and the diffusion coefficient of non-equilibrium electrons was determined by a comparison between the transient reflecting grating and transient reflectivity signals. The diffusion coefficients increases as the carrier density becomes larger. This tendency is qualitatively in agreement with the theoretical prediction that increase of diffusion coefficients is caused by a temperature rise of the carriers and increase of their temperature gradient.

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  • Detection using transient reflecting grating spectroscopy for the ultrafast interaction between photoexcited electrons and adsorbed molecules at a gold surface Reviewed

    K Shibamoto, K Katayama, M Fujinami, T Sawada

    ANALYTICAL SCIENCES   17   S255 - S258   2001

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    We investigated photoexcited electron dynamics, which is considered to be related to the surface enhanced Raman scattering (SERS) effect, using the transient reflecting grating spectroscopic method. Two kinds of vapor-deposited gold films were prepared as SERS substrates. One of them induced the SERS effect (SERS active substrate), while the other did not (SERS inactive substrate). For the SERS active substrate, only the electrons excited at L in the gold band structure decreased faster when crystal violet (CV) molecules were adsorbed on the substrate, while no differences were observed between CV adsorbed and CV non-adsorbed substrates for the SERS inactive substrates. From these results, we concluded that excited electrons only around L in the band structure of gold have some relation to the SERS effect.

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  • Ultrafast two-step thermalization processes of photoexcited electrons at a gold surface: Application of a wavelength-selective transient reflecting grating method Reviewed

    K Katayama, Y Inagaki, T Sawada

    PHYSICAL REVIEW B   61 ( 11 )   7332 - 7335   2000.3

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    We have observed two-step thermalization processes of photoexcited electrons in gold, by using a wavelength-selective transient reflecting grating method that provides information on carrier dynamics at each energy state selectively. We detected ultrafast processes around L and X points in the Brillouin zone. Within 1 ps, two relaxation components (40 +/- 10 and 280 +/- 40 fs) were observed only around L, and only the slower component was observed for every wavelength. We considered that the two relaxation processes occurred due to two kinds of electron-electron (e-e) scattering predicted from the Fermi-liquid theory, because their decay times are in good agreement with the times obtained from the theory. We concluded that faster and slower e-e scatterings physically correspond to the relaxations of the initially photoexcited electrons at the L point, and of nonthermalized electrons at various Brillouin-zone points, respectively.

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  • Generation and observation of GHz ultrasonic waves on liquid surfaces and a liquid/liquid interface by transient reflecting grating method Reviewed

    Sachiyo Ikeda, Kenji Katayama, Takayuki Tanaka, Tsuguo Sawada, Isao Tsuyumoto, Akira Harata

    Journal of Chemical Physics   111 ( 20 )   9393 - 9397   1999.11

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    We optically generated and observed GHz ultrasonic waves on liquid surfaces and a liquid/liquid interface for the first time using the transient reflecting grating (TRG) method. Four kinds of samples were used for measurement of the surfaces
    two types of black ink, an aqueous solution of crystal violet (CV aq solution) and ethanol aqueous solutions of CV. A cyclohexane/CV aq solution interface was used for measurement of the liquid/liquid interface. The 0.7 GHz and 0.6 GHz ultrasonic waves were generated on the liquid surfaces and the liquid/liquid interface, respectively. These ultrasonic waves resemble longitudinal acoustic waves partly localized at the surface, and they cause surface displacement. The amplitudes of TRG signals from surfaces of the CV mixed solvent solutions were found to be greatly affected by both the viscosity and surface tension. This result indicated the viscosity and interface tension must be considered as perturbations in the elastic theory. The strong dependence on interface tension showed the high selectivity of the TRG signals for the interface. © 1999 American Institute of Physics.

    DOI: 10.1063/1.479852

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  • Generation and observation of GHz ultrasonic waves on liquid surfaces and the liquid/liquid interfaces by short pulsed-laser Reviewed

    Sachiyo Ikeda, o

    Journal of Chemical Physics   111 ( 20 )   9393 - 9397   1999.11

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  • Picosecond energy transfer at gold/electrolyte interfaces using transient reflecting grating method under surface plasmon resonance condition Reviewed

    K Katayama, T Sawada, Tsuyumoto, I, A Harata

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   72 ( 11 )   2383 - 2388   1999.11

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    The energy transfer dynamics at gold/NaCl aq (0-0.5 M) interfaces was investigated using our recently developed surface plasmon resonance transient reflecting grating (SPR-TRG) method. We focused on two exponential decays in the SPR-TRG signals. The two decays correspond to the relaxation of hot electrons and interfacial heat transfer, respectively. The intensity of each decay changes systematically with increases in the concentration of NaCl, i.e., the former becomes smaller and the latter becomes larger. Considering the relation between the intensity and the dynamics, we concluded that there is some interaction between the hot electrons and the adsorbate on the interface and that the following temperature rise in gold after relaxation of the hot electrons becomes large: This conclusion shows that an ultrafast energy transfer processes by hot electrons exists, and that the process is hindered by the adsorbate. Finally, we discuss the ultrafast energy transfer in relation to the hot electrons and adsorbate on a molecular scale.

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  • Generation and observation of ultrasonic waves on liquid surfaces by transient reflecting grating method Reviewed

    S Ikeda, K Katayama, Tsuyumoto, I, A Harata, T Kitamori, T Sawada

    PHOTOACOUSTIC AND PHOTOTHERMAL PHENOMENA   463   472 - 474   1999

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    We generated and observed GHz ultrasonic waves on liquid surfaces for the first time using the transient reflecting grating (TRG) method. Three samples were used for measurement: two types of black inks and an aqueous solution of crystal violet (CV). We have investigated the pump power and the solute concentration dependencies of the intensities of the TRG signals from surfaces of the samples. As a result, it was found that these dependencies of the TRG signals are intrinsic to solute and dispersoid. These results presumably suggest that the TRG signals from the liquid surfaces reflect the dynamics of the energy transfer between solute and solvent molecules and of the adsorption and desorption on the liquid surfaces.

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  • Detection of photoinduced electronic, thermal, and acoustic dynamics of gold film using a transient reflecting grating method under three types of surface plasmon resonance conditions Reviewed

    K Katayama, T Sawada, Q Shen, A Harata

    PHYSICAL REVIEW B   58 ( 13 )   8428 - 8436   1998.10

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    Mechanisms of unusual signal enhancement observed for transient reflecting grating (TRG) experiments are investigated under three types of surface plasmon resonance (SPR) conditions, where two pump beams only, a probe beam only, or two pump beams and a probe beam, excite surface plasmon. A gold thin film deposited on a glass prism is measured in the Kretschmann configuration with a temporal resolution of tens of picoseconds. The signal under each SPR condition exhibits different characteristic features in signal intensity and transient behavior unlike the usual non-SPR TRG experiments. Under SPR with pump beams, high conversion efficiency from Light to heat allows detection of a TRG signal 11 times larger in magnitude and much lower in background level than under a non-SPR with them. Under SPR with the probe beam, diffraction caused by heat-induced spatial modulation as described by complex reflection Fresnel coefficients is theoretically proved to enhance the TRG signal and to change transient behavior, which provides a way to get selective observation of heat diffusion near the surface. When both pump and probe beams excite surface plasmons, an additional signal is observed, almost at the same time as the optical pulse, having 100 times larger intensity than the other signals, which is due to electrons excited at the gold surface.

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  • Picosecond energy transfer at Au/electrolyte interfaces investigated by transient reflecting grating method under surface plasmon resonance condition

    Kenji Katayama, Isao Tsuyumoto, Akira Harata, Tsuguo Sawada

    Proceedings of International Seminor on Photothermal Phenomena and their Application   213 - 218   1998.10

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  • 表面プラズモン共鳴過渡反射格子法による金/溶液界面のピコ秒時間分解エネルギー移動計測

    片山建二, 露本伊佐男, 原田 明, 澤田嗣郎

    日本化学会第74春季年会講演要旨集   407   1998.3

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  • Detection of Photo-Induced Electronic, Thermal and Acoustic Dynamics of a Gold Film Using a Transient Reflecting Grating Method under Three Types of Surace Plasmon Resonance Conditions International journal

    Kenji KATAYAMA, Tsuguo SAWADA, Qing SHEN, and Akira HARATA

    Physical Review B   58 ( 13 )   8428 - 8436   1998

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    DOI: 10.1103/PhysRevB.58.8428

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  • GHz ultrasonics measurement using transienet reflecting grating under a surface plasmon resonance condition Reviewed

    Kenji Katayama, Qing Shen, Akira Harata, Tsuguo Sawada

    Proceedings of Acoustical Society of America and Acoustical Society of Japan Third Joint Meeting   575 - 578   1996.12

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  • Unusual enhancement of transient reflecting grating signal under a surface plasmon resonance condition Reviewed

    Kenji Katayama, Qing Shen, Akira Harata, Tsuguo Sawada

    Applied Physics Letters   69 ( 17 )   2468 - 2470   1996.9

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  • Enhancement of transient reflecting grating amplitude under surface plasmon resonance Reviewed

    Q Shen, K Katayama, A Harata, T Sawada

    9TH INTERNATIONAL CONFERENCE ON PHOTOACOUSTIC AND PHOTOTHERMAL PHENOMENA, CONFERENCE DIGEST   345 - 346   1996

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Books

  • Unconventional Liquid Crystals and Their Applications

    Kenji Katayama, Woon Yong Sohn( Role: Joint authorChapter 8)

    De Gruyter  2021.7 

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MISC

  • パターン光照射時間分解位相差顕微鏡の開発 ー光触媒・太陽電池材料の光励起キャリヤを可視化するー Invited

    片山建二

    可視化情報学会誌   10   10 - 13   2020.9

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  • PbS量子ドット薄膜における光励起キャリアダイナミクス-量子ドットサイズの依存性-

    北畠有紀子, 北畠有紀子, 大図修平, DING C., ZHANG Y., 豊田太郎, 早瀬修二, 片山建二, SHEN Q.

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   66th   2019

  • Photo and Thermal Control of Liposome Solubilization

    Takashi Igarashi, Shota Kuwahara, Kenji Katayama

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   86 ( 9 )   1071 - 1075   2013.9

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    The solubilization Of liposomes induced by the addition of surfactants was photocontrolled under temperature control. The instability of the membrane was increased both by photoisomerization of photoresponsive molecules included in the membrane and by changing temperature. By addition of a spiropyran to the liposome membrane, charge-separated structure was formed by UV irradiation, causing local polarization and subsequent motion in the membrane. We found a difference in the solubilization processes in a specific temperature range under UV irradiated and nonirradiated conditions, and figured out that the solubilization of liposomes smaller than 2 mu m can be distinctly photocontrolled in a certain temperature range.

    DOI: 10.1246/bcsj.20130111

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  • Curing Dynamics of Photopolymers Measured by Single-shot Heterodyne Transient Grating Method

    Mika Arai, Tomomi Fujii, Hayato Inoue, Shota Kuwahara, Kenji Katayama

    ANALYTICAL SCIENCES   29 ( 4 )   401 - 404   2013.4

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    The heterodyne transient grating (HD-TG) method was first applied to the curing dynamics measurement of photopolymers. The curing dynamics for various monomers including an initiator (2.5 vol%) was monitored optically via the refractive index change after a single UV pulse irradiation. We could obtain the polymerization time and the final change in the refractive index, and the parameters were correlated with the viscosity, molecular structure, and reaction sites. As the polymerization time was longer, the final refractive change was larger, and the polymerization time was explained in terms of the monomer properties.

    DOI: 10.2116/analsci.29.401

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  • The whole process of phase transition and relaxation of poly(N-isopropylacrylamide) aqueous solution

    Hayato INOUE, Shota KUWAHARA, Kenji KATAYAMA

    Physical Chemistry Chemical Physics   p.3814   2013.1

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  • Local Extraction and Condensation under a Microscope Using the Optically Controlled Phase Separation of a Thermoresponsive Polymer

    Hayato INOUE, Takayuki YAMAMOTO, Shota KUWAHARA, Kenji KATAYAMA

    Chemistry-an Asian Journal   p.108   2013.1

  • PHOTOACOUSTIC AND ULTRAFAST CARRIER DYNAMICS OF Au QUANTUM DOTS GRAFTED ONTO NANOSTRUCTURED TiO_2 ELECTRODES

    SHEN Qing, SUGANUMA Rihito, KATAYAMA Kenji, SAWADA Tsuguo, TOYODA Taro

    29   140 - 142   2008.10

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  • 1-04P-17 Photoacoustic Spectra and Ultrafast Carrier Dynamics of Nanostructured TiO_2 Films Sensitized with CdS Quantum Dots(Poster session 1)

    Sato Akira, Shen Qing, Katayama Kenji, Sawada Tsuguo, Toyoda Taro

    Proceedings of Symposium on Ultrasonic Electronics   28   49 - 50   2007.11

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  • P3-38 Photoacoustic and Photoelectrochemical Characterization of CdSe Quantum Dots Grafted onto Fluorine-Doped Tin Oxide (FTO) Glass and Nanostructured SnO_2 Electrode(Poster session 3)

    Toyoda Taro, Yanai Makoto, Shen Qing, Katayama Kenji, Sawada Tsuguo

    Proceedings of Symposium on Ultrasonic Electronics   27   449 - 450   2006.11

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  • 特集 化学のフロンティア2000 はばたけ若き研究者たち 超高速現象を簡単に測る -レンズなしのフェムト秒時間分解分光法-

    片山建二

    化学と工業   57 ( 2 )   91 - 94   2004.2

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  • [特集2]微細加工を支える計測・制御センサ応用システム 固液界面ナノ領域を分析する光熱変換分光法

    片山建二, 澤田嗣郎

    M & E3月号   96 - 100   2002.3

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  • 進捗総説 光熱変換分光法

    由井宏治, 片山建二, 澤田嗣郎

    ぶんせき7月号   319   361 - 365   2001.7

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  • 最近の展望 光熱変換分光法の展開

    片山建二, 由井宏治, 澤田嗣郎

    応用物理   70 ( 6 )   672 - 676   2001.6

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  • フェムト秒の世界を測る

    片山建二, 澤田嗣郎

    化学と教育   47 ( 6 )   390 - 391   1999.6

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    DOI: 10.20665/kakyoshi.47.6_390

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  • Study of superspeed phenomenon of liquid surface using picosecond laser and ripples.

    池田幸代, 片山建二, 露本伊佐男, 沢田嗣郎, 原田明

    日本分析化学会年会講演要旨集   46th   1997

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Presentations

  • ベイズ最適化による効率的計測を利用した時間分解計測

    片山建二

    分析化学会第69年会  2020.9 

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  • 界面活性剤溶液中の光駆動アクティブドロプレット Invited

    片山建二, 酒井陽太

    第71回コロイドおよび界面化学討論会  2020.9 

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  • 時間分解パターン光照射位相差顕微鏡を用いた光デバイス中の電荷ダイナミクスマッピング

    片山建二, 海老原誠, 仲元寺達也

    2020年web光化学討論会  2020.9 

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  • Photo-induced charge dynamics in photo-devices -sphotocatalysis, water splitting, solar cells Invited International conference

    Kenji Katayama

    Seminar @ McMaster University  2019.9 

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  • Phase Transition Dynamics of Liquid Crystals Observed by Pattern-Illumination Phase Imaging Invited International conference

    Kenji Katayama

    Optics of Liquid Crystals 2019  2019.9 

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  • Photo-induced charge dynamics in photo-devices -solar cell, photocatalysis, water splitting Invited International conference

    Kenji Katayama

    Seminar @ San Diego State University  2019.8 

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  • Direct imaging of phase transition of liquid crystals by nanosecond time-resolved transient grating phase imaging Invited International conference

    Kenji Katayama

    SPIE Liquid Crystals XXIII  2019.8 

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  • Photo-controllable active liquid crystalline droplet Invited International conference

    Kenji Katayama

    The 23th International Symposium on Advanced Display Material and Devices (ADMD)  2019.7 

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  • Photo-induced charge dynamics in photo-devices -solar cell, photocatalysis, water splitting Invited International conference

    Kenji Katayama

    Seminar @ Shenzhen Institute of Advanced Technology, CAS  2019.7 

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  • Photo-controllable active liquid crystalline droplet Invited International conference

    Kenji Katayama

    The 41st PIERS  2019.6 

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  • Photo-induced dynamics of photo-devices -solar cell, photocatalysis, water splitting Invited International conference

    Kenji Katayama

    Seminar at OIST  2019.1 

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  • Photo-response analysis of photo-devices by transient grating phase imaging microscopy

    Kenji Katayama

    日本分析化学会第67年会  2018.9 

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  • The Origin of optical nonlinearity of liquid crystals revealed by transient grating imaging Invited International conference

    Kenji Katayama

    International Meeting on Information Display (IMID 2018)  2018.8 

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  • Origin of optical nonlinearity of photo-responsive liquid crystals revealed by transient grating imaging Invited International conference

    K. Katayama, Kin-ichiro Nagasaka, Minaka Minagawa, Woon Yoon Soh

    SPIE Optics+Photonics, Liquid Crystals XXII  2018.8 

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  • Photo-induced Orientation Change of Photo-responsive Liquid Crystals Invited International conference

    Kenji Katayama

    The 40th PIERS  2018.8 

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  • Origin of optical nonlinearity of photo-responsive liquid crystals revealed by transient grating imaging Invited International conference

    Kenji Katayama

    Photonics North 2018  2018.6 

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  • Photo-induced dynamics of photo-devices -Solar cells, photocatalysis, water splitting Invited International conference

    Kenji Katayama

    Seminar at VISTEC  2018.3 

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  • ソフトマターの相変化で何が起こるか? -時間分解法・顕微分光法による観察

    日本化学会 北海道支部セミナー  2017.12 

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  • 格子パターン励起位相差顕微鏡による液晶の相転移領域伝搬の直接計測

    第7回ソフトマター研究会  2017.10 

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  • Heterogeneous reaction dynamics revealed by transient grating technique

    Boston College, Physical Chemistry Seminar  2014.9 

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  • Molecular dynamics in azobenzene liquid crystal polymer films studied by transient grating technique

    S. Kuwahara, T. Ikeda

    SPIE Optics+Photonics, Liquid Crystal XVIII  2014.8 

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  • Carrier dynamics in dye or quantum dot sensitized solar cells

    S. Kuwahara

    6th East Asia Symposium on Functional Dyes and Advanced Materials  2013.9 

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  • Molecular dynamics of liquid crystal revealed by transient grating technique

    17th International Symposium on Advanced Display Materials and Devices  2013.6 

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  • 高耐圧ワンタッチ脱着マイクロコネクターの開発(2)

    片山建二, ほか

    日本分析化学会第54年会講演要旨集,日本分析化学会  2005.9 

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  • フローイング熱レンズ効果を利用したマイクロチップ内流量の非接触・in-situ測定

    菊谷善国, ほか

    電気学会研究会、フィジカルセンサ研究会要旨集,電気学会  2005.9 

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  • Structural influence on the photoexcited carrier dynamics of TiO2 films characterized using lens-free heterodyne detection transient grating technique

    Q. Shen

    Abstract of 11th Asian Chemical Congress/Committee of 11th ACC  2005.8 

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  • 高耐圧ワンタッチ脱着マイクロコネクターの開発

    片山建二, ほか

    シンポジウム「マイクロ化学研究開発の全容」要旨集,シンポジウム「マイクロ化学研究開発の全容」実行委員会  2005.8 

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  • Differences of carrier dynamics of anatase and rutile TiO2 nanostructured electrodes and the effect of CdSe quantum dot deposition

    Qing Shen, o

    ナノ学会第3回大会講演予稿集,ナノ学会  2005.3 

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  • CdSe量子ドット増感ナノチューブ・ナノワイヤTiO2電極の光吸収・光電気化学特性とキャリアダイナミクス

    沈青, ほか

    2005年春季第52回応用物理学関係連合講演会要旨集,応用物理学会  2005.3 

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  • レンズフリー過渡格子法の開発による分光分析

    山口真広, 片山建二, 藤浪真紀, 澤田嗣郎

    日本分析化学会第53年会講演要旨集,日本分析化学会  2004.9 

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  • 固液界面を利用したレーザーアブレーション深さ制御

    米久保秀明, 片山建二, 藤浪真紀, 澤田嗣郎

    日本分析化学会第53年会講演要旨集,日本分析化学会  2004.9 

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  • Lens-free heterodyne transient grating technique

    Kenji Katayama, Tsuguo Sawada, Keith A. Nelson

    Abstract of 13th International Conference on Photothermal and Photoacoustic Phenomena/Committee of ICPPP 13  2004.7 

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  • ナノ構造TiO2電極に吸着したCdSe量子ドットの光励起キャリアのダイナミクス

    沈 青, 片山建二, 澤田嗣郎, 豊田太郎

    2004年春季第51回応用物理学関係連合講演会講演予稿集,応用物理学会  2004.3 

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  • Studies of CdSe-sensitized nanostructured TiO2 electrodes: optical absorption, photoelectrochemical current and ultrafast carrier dynamics

    Qing Shen, Dai Arae, Kenji Katayama, Tsuguo Sawada, Taro Toyoda

    Abstract of The 6th AIST International Symposium on Photoreaction Control and Photofunctional Materials/National Institute of Advanced Industrial Science and Technology  2003.9 

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  • 過渡反射格子スペクトル法を用いた表面増強ラマン散乱素過程に見られる電荷移動の追跡

    芝本幸平, 片山建二, 藤浪真紀, 澤田嗣郎

    第64回分析化学討論会講演要旨集,日本分析化学会  2003.6 

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  • レンズフリー過渡格子法の開発と固体・液体試料への適用例

    山口真広, 片山建二, 藤浪真紀, 澤田嗣郎

    第64回分析化学討論会講演要旨集,日本分析化学会  2003.6 

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  • 固液界面におけるフェムト秒パルスレーザー加工

    米久保秀明, 片山建二, 藤浪真紀, 澤田嗣郎

    第64回分析化学討論会講演要旨集,日本分析化学会  2003.6 

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  • 簡易型超高速時間分解分光法の開発とさまざまな試料への応用

    片山建二, 山口真広, 澤田嗣郎

    平成15年度日本分光学会春季講演会講演要旨集,日本分光学会  2003.5 

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  • フェムト秒レーザーを用いた固液界面でのレーザー加工

    片山建二, 米久保秀明, 澤田嗣郎

    平成15年度日本分光学会春季講演会講演要旨集,日本分光学会  2003.5 

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  • Ultrafast charge transfer in surface enhanced Raman scattering processes detected with transient reflecting grating spectroscopy

    Kohei Shibamoto, Kenji Katayama, Masanori Fujinami, Tsuguo Sawada

    Abstract of Nanoarchitectonics Workshop 2003 Nano-Space Engineering for Nanoarchitectonics (NSENA 2003)/Committee of NSENA 2003  2003.3 

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  • Ultrafast carrier dynamics of CdSe-sensitized nanostructured TiO2 electrodes using lens-free heterodyne detection transient grating technique

    Qing Shen, Kenji Katayama, Tsuguo Sawada, Taro Toyoda

    Abstract of 7th International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures (ICACS 2003)/Committee of ICAC 2003  2003.3 

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  • 固液界面におけるフェムト秒パルスレーザー加工

    片山建二, 米久保秀明, 澤田嗣郎

    2003年春季第50回応用物理学関係連合講演会要旨集,応用物理学会  2003.3 

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  • ヘテロダイン計測を用いた簡易型キャリヤダイナミクス計測法の開発

    片山建二, 山口真広, 澤田嗣郎

    2003年春季第50回応用物理学関係連合講演会要旨集,応用物理学会  2003.3 

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  • レンズフリーヘテロダイン過渡格子法を利用した光励起分子ダイナミクス計測

    山口真広, 片山建二, 藤浪真紀, 澤田嗣郎

    日本化学会第83春季年会講演要旨集,日本化学会  2003.3 

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  • 固液界面におけるフェムト秒パルスレーザー加工

    米久保秀明, 片山建二, 藤浪真紀, 澤田嗣郎

    日本化学会第83春季年会講演要旨集,日本化学会  2003.3 

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  • 過渡反射格子スペクトル法を用いたSERS効果発現過程に見られる超高速キャリア移動過程の追跡

    芝本幸平, 片山建二, 藤浪真紀, 澤田嗣郎

    分子構造総合討論会2002要旨集,分子構造討論会運営委員会  2002.10 

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  • 過渡反射格子スペクトル法を用いた半導体表面の欠陥評価

    片山建二, 道念裕司, 澤田嗣郎

    日本分析化学会第51年会講演要旨集,日本分析化学会  2002.9 

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  • Transient reflecting grating spectroscopy used for defect analysis in surface region of semiconductors

    Kenji Katayama, Hiroshi Donen, Tsuguo Sawada

    Abstract of 12th International Conference on Photothermal and Photoacoustic Phenomena/Committee of ICPPP 12  2002.6 

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  • Ultrafast charge transfer in surface enhanced raman scattering processes detected with transient reflecting grating spectroscopy

    Kohei Shibamoto, Kenji Katayama, Masanori Fujinami, Tsuguo Sawada

    Abstract of 12th International Conference on Photothermal and Photoacoustic Phenomena/Committee of ICPPP 12  2002.6 

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  • 吸着種存在下での金電極界面における超高速電子的相互作用の観測

    村川暁, 片山建二, 藤浪真紀, 澤田嗣郎

    第63回分析化学討論会講演要旨集,日本分析化学会  2002.5 

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  • 超高速時間分解分光法を用いた表面増強ラマン散乱の素過程の観測

    片山建二, 澤田嗣郎

    平成13年度日本分光学会秋季講演会講演要旨集,日本分光学会  2001.12 

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  • Evaluation of thermal and elastic properties for solid surfaces using transient reflecting grating method

    Kenji Katayama, Tsuguo Sawada

    Abstract of 10th International Congress on Fracture/Committee of ICF 10  2001.12 

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  • Recent advances of photothermal spectroscopy

    Tsuguo Sawada, Kenji Katayama

    Abstract of 10th International Congress of Fracture/Committee of ICF 10  2001.12 

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  • Influence of annealing process on ultrafast carrier dynamics for an ion-implanted silicon surface

    Hiroshi Donen, Kenji Katayama, Tsuguo Sawada

    Abstract of 10th International Congress on Fracture/Committee of ICF 10  2001.12 

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  • フェムト秒時間分解計測法を用いた表面増強ラマン散乱効果の素過程の観測(2)

    芝本幸平, 片山建二, 藤浪真紀, 澤田嗣郎

    日本分析化学会第50年会講演要旨集,日本分析化学会  2001.11 

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  • ナノ領域の分析化学

    片山建二, 由井宏治, 澤田嗣郎

    第5回分析化学東京シンポジウム講演要旨集,日本分析化学会  2001.9 

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  • フェムト秒時間分解計測法を用いた表面増強ラマン散乱効果の素過程の観測

    片山建二, 芝本幸平, 澤田嗣郎

    日本化学会第80秋季年会講演要旨集,日本化学会  2001.9 

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  • フェムト秒時間分解過渡反射格子法を用いた半導体表面分析

    片山建二, 道念裕司, 澤田嗣郎

    第45回日本学術会議材料研究連合講演会要旨集,日本材料学会  2001.9 

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  • Influence of annealing process on ultrafast carrier dynamics for an ion-implanted silicon surface

    Hiroshi Donen, Kenji Katayama, Tsuguo Sawada

    Abstract of International Congress on Analytical Sciences 2001/Committee of ICAS 2001  2001.8 

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  • Ultrafast transient reflecting grating spectroscopy

    Kenji Katayama, Tsuguo Sawada

    Abstract of International Congress on Analytical Sciences 2001/Committee of ICAS 2001  2001.8 

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  • Fundamental processes of surface enhanced Raman scattering detected with transient reflecting grating spectroscopy

    Kohei Shibamoto, Kenji Katayama, Tsuguo Sawada

    Abstract of International Congress on Analytical Sciences 2001/Committee of ICAS 2001  2001.8 

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  • 光熱変換分光法を用いた薄膜のキャラクタリゼーション

    片山建二, 澤田嗣郎

    日本分光学会第37回夏期セミナー講演要旨集,日本分光学会  2001.6 

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  • 過渡反射格子スペクトル法を用いてSERS効果の素過程に関与する吸着分子-金間の超高速キャリア相互作用の観測

    芝本幸平, 片山建二, 藤浪真紀, 澤田嗣郎

    第62分析化学討論会講演要旨集,日本分析化学会  2001.6 

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  • フェムト秒時間分解過渡反射格子スペクトル法を用いた半導体表面のキャリヤダイナミクス測定

    片山建二, 澤田嗣郎

    平成13年度日本分光学会春季講演会要旨集,日本分光学会  2001.5 

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  • フェムト秒時間分解過渡反射格子スペクトル測定法によるシリコン表面のキャリヤダイナミクス測定(2)

    片山建二, 稲垣洋平, 道念裕司, 澤田嗣郎

    日本化学会第79春季年会要講演旨集,日本化学会  2001.3 

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  • フェムト秒時間分解過渡反射格子スペクトル測定法によるシリコン表面のキャリヤダイナミクス測定(3) イオン注入Siのアニール過程において

    道念裕司, 片山建二, 藤浪真紀, 澤田嗣郎

    日本化学会第79春季年会講演要旨集,日本化学会  2001.3 

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  • Detection using transient reflecting grating spectroscopy for the ultrafast interaction between photoexcited electrons and adosorbed molecules at a gold surface

    Kohei Shibamoto, Kenji Katayama, Tsuguo Sawada

    Abstract of International Chemical Congress of Pacific Societies 2000-Pacifichem/Committee of Pacifichem 2000  2000.12 

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  • Ultrafast carrier dynamics at various semiconductor surfaces using femtosecond transient reflecting grating spectroscopy

    Yohei Inagaki, Kenji Katayama, Tsuguo Sawada

    Abstract of International Chemical Congress of Pacific Societies 2000-Pacifichem/Committee of Pacifichem 2000  2000.12 

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  • Detection of ultrafast carrier dynamics at silicon surface using femtosecond transient reflecting grating spectroscopy

    Kenji Katayama, Tsuguo Sawada

    Abstract of International Chemical Congress of Pacific Societies 2000-Pacifichem/Committee of Pacifichem 2000  2000.12 

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  • 過渡反射格子スペクトル法を用いた金から吸着分子への高速エネルギー移動の観測

    片山建二, 芝本幸平, 藤波真紀, 澤田嗣郎

    日本分析化学会第49年会講演要旨集,日本分析化学会  2000.9 

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  • 超高速時間分解分光法を用いた固体表面でのキャリヤ挙動の追跡

    片山建二, 稲垣洋平, 芝本幸平, 藤波真紀, 澤田嗣郎

    第4回分析化学東京シンポジウム講演要旨集,日本分析化学会  2000.9 

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  • Direct measurement of non-equilibrium carrier diffusion at a Si surface

    Yohei Inagaki, Kenji Katayama, Masanori Fujinami, Tsuguo Sawada

    Abstract of 11th International Conference on Photothermal and Photoacoustic Phenomena/Committee of ICPPP 11  2000.6 

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  • Detection using transient reflecting grating spectroscopy for the ultrafast interaction between photoexcited electrons and adsorbed molecules at a gold surface

    Kohei Shibamoto, Kenji Katayama, Masanori Fujinami, Tsuguo Sawada

    Abstract of 11th International Conference on Photothermal and Photoacoustic Phenomena/Committee of ICPPP 11  2000.6 

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  • Femtosecond carrier dynamics at each energy state at gold surface: Application of a new wavelength selective transient reflecting grating method

    Kenji Katayama, Yohei Inagaki, Tsuguo Sawada

    Abstract of 11th International Conference on Photothermal and Photoacoustic Phenomena/Committee of ICPPP 11  2000.6 

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  • フェムト秒時間分解過渡反射格子法によるシリコン表面のキャリヤダイナミクス測定

    片山建二, 藤波真紀, 澤田嗣郎

    第61回分析化学討論会講演要旨集,日本分析化学会  2000.5 

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  • フェムト秒時間分解過渡反射格子スペクトル法によるシリコン表面のキャリヤダイナミクス測定

    片山建二, 藤波真紀, 澤田嗣郎

    平成12年度日本分光学会春季講演会講演要旨集,日本分光学会  2000.5 

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  • 過渡レンズ分光法によるガラス中に分散したCdSxSe1-xナノ微粒子の緩和ダイナミクスの計測

    沈 青, ほか

    第61回分析化学討論会講演要旨集,日本分析化学会  2000.5 

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  • フェムト秒時間分解過渡反射格子スペクトル法によるシリコン表面のキャリヤダイナミクス測定

    片山建二, 藤波真紀, 澤田嗣郎

    日本化学会第78回春季年会講演要旨集,日本化学会  2000.3 

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  • 過渡反射格子法による液体表面ギガヘルツ超音波の解析(2)

    谷口大賀, 片山建二, 藤波真紀, 澤田嗣郎

    日本化学会第78回春季年会講演要旨集,日本化学会  2000.3 

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  • 過渡反射格子法を用いた固体表面の熱、弾性物性の評価

    片山建二, 澤田嗣郎

    第20回日本熱物性シンポジウム講演論文集,日本熱物性学会  1999.10 

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  • 超高速光熱変換現象を用いた固体表面、固液界面のナノ領域物性評価法の開発

    片山建二, 稲垣洋平, 藤浪眞紀, 澤田嗣郎

    第3回分析化学東京シンポジウム講演要旨集,日本分析化学会  1999.9 

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  • フェムト秒白色プローブパルス光を用いた過渡反射格子スペクトル法の開発

    片山建二, 露本 伊佐男, 原田 明, 澤田嗣郎

    分析化学討論会第60年会講演要旨集,日本分析化学会  1999.5 

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  • 過渡反射格子法による液液界面ダイナミクスの観察

    池田幸代, ほか

    日本化学会第76春季年会講演要旨集,日本化学会  1999.3 

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  • 超高速光熱変換分析法による固液界面エネルギー移動計測

    露本伊佐夫, ほか

    第2回分析化学東京シンポジウム講演要旨集,日本分析化学会  1998.9 

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  • 表面プラズモン共鳴を利用した高感度過渡反射格子法による金の励起電子のフェムト秒ダイナミクス測定

    片山建二, 露本伊佐男, 澤田嗣郎

    日本化学会第75秋季年会講演要旨集,日本化学会  1998.9 

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  • Generation and observation of ultrasonic waves on liquid surfaces by transient reflecting grating method

    Sachiyo Ikeda, o

    Abstract of Photothermal and Photoacoustic Phenomena Tenth International Conference/Committee of ICPPP 10  1998.8 

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  • Picosecond energy transfer at gold / solution interfaces using a transient reflecting grating method

    Kenji Katayama, Qing Shen, Akira Harata, Tsuguo Sawada

    Abstract of Oji International Seminor on Photothermal Phenomena and Their Applications/The University of Tokyo  1998.7 

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  • 表面プラズモン共鳴現象を利用した過渡反射格子法による固液界面計測

    片山建二, 露本 伊佐男, 原田 明, 澤田嗣郎

    日本分析化学会第46年会講演要旨集,日本分析化学会  1997.10 

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  • 高速光熱変換法を用いた金単結晶/溶液界面での熱伝導プロセスの解析

    片山建二, 鈴木敬紀, 露本伊佐男, 原田 明, 澤田嗣郎

    日本化学会第73秋季年会講演要旨集,日本化学会  1997.9 

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  • 全反射過渡格子法を用いた表面プラズモンの高速光熱変換計測

    片山建二, 沈 青, 原田 明, 澤田嗣郎

    日本化学会第71秋季年会講演要旨集,日本化学会  1996.10 

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  • 全反射過渡格子法を用いた表面プラズモンの高速光熱変換測定

    片山建二, 沈 青, 原田明, 澤田嗣郎

    第57回分析化学討論会講演要旨集,日本分析化学会  1996.5 

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Awards

  • 日本分析化学会奨励賞

    2007.4   日本分析化学会   近接場ヘテロダイン過渡格子分光法の開発とその応用

  • 井上研究奨励賞

    2003.2   財団法人 井上科学振興財団   過渡反射格子法に基づく新しい超高速光熱変換測定法の開発とその応用

Research Projects

  • Optimization of photocatalytic materials with a combination of analytical data and machine learning

    Grant number:22K05158  2022.4 - 2025.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)  Chuo University

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    Grant amount: \4160000 ( Direct Cost: \3200000 、 Indirect Cost: \960000 )

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  • 変調光誘起位相差顕微鏡による光生成キャリヤ寿命・移動物性評価法

    2016.10 -  

    JSTさきがけ  公的機関からの助成金(私大助成等) 

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  • 酸化・還元機能を空間的に分離した高機能光触媒反応基板の作成

    2016.8 -  

    日本板硝子材料工学助成会  民間助成金 

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    Grant type:Competitive

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  • 増感型太陽電池の再結合を調べる顕微分光分析法

    2014.10 - 2015.11

    住友財団  奨学寄付金 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \2500000

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  • スペックルパターン位相差顕微鏡を用いた3次元光誘起電子顕微測定法

    2015.4 -  

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省) 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \3800000

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  • 増感型太陽電池の再結合を調べる顕微分光分析法

    2014.10 -  

    奨学寄付金 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \2500000

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  • マイクロスケール実験を用いた物理化学実験教育

    2013.4 - 2014

    科学技術振興機構  奨学寄付金 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \1700000

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  • マイクロチップと新型動的光散乱法を用いたリポソームの反応速度解析法の開発

    2011.4 - 2014

    旭硝子財団  奨学寄付金 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \5590000

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  • マイクロスケール実験を用いた化学工学実験教育

    2012.4 - 2013

    科学技術振興機構  奨学寄付金 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \1700000

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  • マイクロチップ用動的光散乱法を用いたリポソームの反応速度解析法の開発

    2011.4 - 2012

    中谷電子計測技術振興財団  奨学寄付金 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \2000000

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  • 酸化チタンナノ粒子薄膜の熱伝導と電子・ホール輸送特性

    2011.4 - 2012

    日本板硝子材料工学助成会  奨学寄付金 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \1350000

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  • Photodegradation dynamics of dye molecuses measured by near-field heterodyne transient grating method

    2007.4 - 2009.3

    受託研究費 協和発酵ケミカルシーズコンテスト 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \4000000

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  • Hybrid detector for microchip using the near-field light of diffractive optics

    2006.4 - 2009.3

    文部科学省  科学研究費補助金 若手研究(A) 

    片山 建二

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  • Compact equipment of terahertz spectroscopy using phonon polariton

    2007.4 - 2008.3

    その他 中央大学特定課題研究費 

    片山建二

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    Authorship:Principal investigator  Grant type:Competitive

    Grant amount: \1590000

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  • Ultrafast carrier dynamics at solid surfaces using heterodyne transient grating spectroscopy

    2003.9 - 2005.3

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省) 海外特別研究員 

    片山建二

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  • Highly-sensitive vibrational spectrascopy with spatial resolution beyond diffraction limit

    Grant number:14340189  2002 - 2004

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)  NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE AND TECHNOLOGY

    FUTAMATA Masayuki, MATSUDA Naoki, SHIMIZU Toshimi, SAWADA Tsuguo

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    Grant amount: \12500000 ( Direct Cost: \12500000 )

    The following results were obtained.
    1)Single molecule detection using SERS : a)Critical importance of the junction was proved using correlation between SERS and elastic scattering spectra from the same Ag nanoparticles, 2)adenine which has no electronic absorption in visible wavelength provides enormous enhancement similar to dye, 3)emission spectra originated from inelastic scattering of surface electron by adsorbed species was found for the first time.
    2)ATR-SNOM-Raman spectroscopy : a)interference or multiple scattering of LSP field do no essentially affect the near-field Raman imaging.
    3)FT-IR based ATR near-field spectrometer was built to demonstrate tip-enhanced IR absorption.
    4)Slab optical waveguide spectroscopy : ITO based waveguide was fabricated and applied to elucidate potential dependence of biomolecules with significantly high sensitivity.

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  • Development of new Raman spectroscopy using the electromagnetic enhancement of surface enhanced Raman scattering effect

    2002.4 - 2003.9

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省) 若手研究(A) 

    片山建二

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  • 極短パルスレーザーによる電子過剰水溶液の物性研究とその分光学的応用

    Grant number:15655022  2003    

    日本学術振興会  科学研究費助成事業  萌芽研究  東京大学

    澤田 嗣郎, 池添 泰弘, 片山 建二, 藤浪 眞紀

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    Grant amount: \3500000 ( Direct Cost: \3500000 )

    本研究の目的は極短パルスレーザー等を用いて過渡的に水中に多量の電子を発生し、その光学応答、特に非線形光学効果を分光学的に解析し、その光学効果を分析化学的に応用することである。
    まず、ピコ秒のレーザーを用いて、基礎化学的に興味深いだけでなく、工業的にも重要なエタノールの希薄溶液中に多量に電子を発生させて、その時放射される非線形光学効果(誘導ラマン散乱)を観測した。その結果、電子の多量発生による誘導ラマン散乱の著しい増強効果が確認され、この性質を利用して、エタノール分子の周囲の水分子の溶媒和構造について議論した。
    次に、電子生成領域の水の構造と増強効果の原因を探るため、純水において電子を多量発生させた際の誘導ラマン散乱の前方及び後方成分を同時に時間分解測定し、電子生成領域の詳細な情報を得ることを試みた。その結果、前方および後方で全く異なるスペクトルが測定され、特に後方散乱領域で電子と水の相互作用に起因すると思われる特徴的なピーク見出した。スペクトルの波数位置とピークの相対強度などから、電子による分極率の変化が増強に重要な役割を果たしていることを見出した。また量子化学計算を用いた理論的研究にも着手した。
    最後に、本現象の適用範囲を水溶液中から一般の有機溶媒にも広げるため、ベンゼンとトルエンの混合溶媒にも本現象を適用した。その結果、励起過渡種と溶媒分子との相互作用によるラマン散乱断面積の増強効果を見出し、理論計算によってその効果を検証した。

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  • Development of near field laser induced ablation spectroscopy

    Grant number:14350443  2002 - 2003

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)  The University of Tokyo

    FUJINAMI Masanori, IKEZOE Yasuhiro, KATAYAMA Kenji, SAWADA Tsuguo

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    Grant amount: \14900000 ( Direct Cost: \14900000 )

    The aim of the research project is to develop the near-field laser induced ablation spectroscopy and to analyze the chemical composition to detect the atomic emission within 100 nmφ area. The problem is to overcome the diffraction limit of light and confine the ablation area induced by laser beam. Our idea is to utilize the tip enhanced field with femtosecond pulse laser beam and such a enhanced field is effective within several tens nanometer. We expect that the excited atoms and ions emit characteristic light after ablation and information on chemical composition is obtained.
    Near-filed optical scanning microscope has been installed by ourselves. Pulsed femtosecond light with 800 nm and 150 fs pulse width is used as an excitation light, and irradiates the W. tip. It has been found that irradiation with 13 mJ/cm^2 induces the ablation area with 50 nm width and 10 nm depth for Au and Al thin films on a glass. Without W tip in irradiation, no ablation takes place. This ablation area is beyond the diffraction limit and a combination with femtosecond pulse laser and tip-enhanced field is effective to induce nano-area ablation. On the other hand, no light emission has been observed. It is considered for the reason that pulse light is too. short to excite the ablated atoms and ions. Further, optimization of optical geometry is needed.
    In this research, we have also developed the photothermal scanning near field optical microscope (PT-SNOM). The lateral resolution is enhanced to 200 nm. PT-SNOM can be applied to detect the non-fluorescent molecules, which are inactive to biomaterials. Further, tip enhanced photothermal effect can be found out and the apertureless PT-SNOM can be installed.

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  • Development of low-frequency domain spectroscopy at liquid interfaces using ultra-short laser pulse and its applications

    Grant number:14350442  2002 - 2003

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)  The University of Tokyo

    SAWADA Tsuguo, IKEZOE Yasuhiro, KATAYAMA Kenji, FUJINAMI Masanori

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    Grant amount: \14700000 ( Direct Cost: \14700000 )

    The aim of this research is the observation of the collective behavior of the molecular a ssemblies at liquid interfaces in the low-frequency domain. At first, as important systems of the collective behaviors of the molecular assemblies at liquid interfaces, we investigate d the dynamic behavior of surfactants molecules in nonlinear chemical oscillation system and the kinetics of the hydrolysis reactions of biological membrane. We obtained new information of these systems in. terms of the dynamic behavior of the ion transfer across the membrane and specific interaction between ions and molecules at the interfaces.
    We have developed the equipment to observe vibrational spectra of the molecular assemblies at liquid interfaces in low-frequency domain. We have succeeded to obtain low-frequency vibrational spectrum from the surface of GaAs plate through the change of SHG signals. induced by the change of the nonlinear susceptibility due to the coherent vibration of the molecular assemblies or lattices. We have also applied the transient grating configuration to the abovementioned system, we successfully obtained background free signal from the air/liquid interface where coumarin dyes were dispersed.

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  • 光熱変換分光法を用いた液液界面ナノ領域における分子集団挙動・分子間相互作用の研究

    Grant number:13129203  2001 - 2003

    日本学術振興会  科学研究費助成事業  特定領域研究  東京大学

    沢田 嗣郎, 池添 泰弘, 片山 健二, 藤浪 眞紀

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    Grant amount: \34100000 ( Direct Cost: \34100000 )

    本研究では、我々が独自に開発してきた時間分解準弾性レーザー散乱(QELS)法と、フェムト秒高出力レーザーを用いた超高速界面分光法の二つの測定手法により、液液界面ナノ空間に特有な非線形反応や分子間相互作用を観測し、新しい界面物理化学を見出すことを目的とした。
    QELS法を用いた研究として、本年度は主に二つの研究を行った。一つは、水とニトロベンゼンの界面における非線形化学振動現象の研究である。界面でのイオンの一斉吸着現象が対流に伴うイオンの強制輸送によること、また、一旦発生した対流の減衰が振動過程の端緒となることが見出され、化学振動現象の全貌が明らかとなった。もう一つは、水とヘプタンの界面におけるAOT逆ミセルの崩壊とそれに伴う吸着過程における界面張力の異常減少効果に関する研究である。超高速蛍光分析の結果とQELS信号と比較したところ、界面が過渡的に混合された状態が見出された。液液界面が、単なる2相の境界ではなく、ナノメートルスケールで混ざりあった領域であり、しかもそれが徐々に変化することを実測した例は他に無く、極めて重要な発見と言える。
    超高速界面分光法に関しては、測定周波数領域の拡大と液体界面測定に向けた装置の高感度化を行った。前者については回折格子対とプリズム対を用いた光学系を導入し、これまで0-150cm^<-1>であった観測周波数領域を約2倍の0-300cm^<-1>まで拡大することに成功した。これにより、並進・回転運動に加えて水素結合などを介したメソ構造を鋭敏に反映するphonon-likeな振動運動も観測可能となった。後者については従来のポンプ-プローブ光学配置を過渡格子光学配置に改良し、装置の感度を大幅に向上させた。その結果、界面領域の分子間相互作用を議論するうえで重要な手がかりとなる光電場に対する分子の電子応答や配向変化を気/液界面において観測することにはじめて成功した。

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  • Development of ultrafast dynamics at solid surfaces using transient grating spectroscopy

    2000.4 - 2002.3

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省) 奨励研究 

    片山建二

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    Grant amount: \3000000

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  • Development of photothermal scanning near-field optical microscope

    Grant number:12555234  2000 - 2001

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)  The University of Tokyo

    FUJINAMI Masanori, KATAYAMA Kenji, SAWADA Tsuguo

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    Grant amount: \13200000 ( Direct Cost: \13200000 )

    Much attention to a scanning near-field optical microscope(SNOM) has been paid in this decade by overcoming the diffraction limit to reach nanometeric size. Photothermal spectroscopy is highly sensitive and versatile technique, which is applicable for non-fluorescent molecules, so that photothermal (PT) -SNOM can be used as a promising tool in thin-film analysis. In this study we have developed the PT-SNOM and investigated the performance. The molecules are excited by the evanescent wave emitted from the small aperture of the optical fiber probe and the probe laser beam for detection of the induced refractive index is coaxially introduced with the excited beam.
    The PT-SNOM was based on inverted optical microscope. A He-Cd laser was used as an excitation source at 422 nm, while a He-Ne laser as a probe beam at 633 nm. Both the laser beams were coaxially introduced into a metal-coated optical fiber probe with an apex diameter of around 100 nm. A shear-force feedback kept the fiber probe-sample distance of 10 nm. The transmitted probe beam was collected by the objective lens and passed through a holographic notch filter to remove excitation light of 422 nm.
    The thin film of gold (80 nm) on a glass is used for the sample and the photothermal signal image can be obtained in PT-SNOM. The irradiation either of excitation laser or of probe laser does not results in any signals. This is the first evidence of detection of photothermal signal and image in SNOM. The space resolution is estimated to be 1 μm. Fast modulation frequency for excitation laser and Short time constant in lock-in amplifier are required in order to get the photothermal signal image, so the improvement of S/N ratio is in progress.

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  • THE DEVELOPMENT OF TIME-RESOLVED TWO-DIMENSIONAL IMAGING INSTRUMENT FOR MONITORING MOLECULAR BEHAVIOR AT LIQUID/LIQUID INTERFACES

    Grant number:12450336  2000 - 2001

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)  The University of Tokyo

    SAWADA Tsuguo, KATAYAMA Kenji, YUI Hiroharu, FUJINAMI Masanori

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    Grant amount: \15000000 ( Direct Cost: \15000000 )

    We have developed new instrument that enable us to monitor molecular behaviors at liquid/liquid interface without any perturbation. The instrument is based on Time-Resolved Quasi-Elastic Laser Scattering (QELS) method, which we have developed. In this research project, we aimed at following points, (1) To apply the QELS technique to two-dimensional imaging measurements, all necessary beams to measure QELS signal (generating scattered light and local oscillator) and QELS signals are corrected by only one lens. We can obtain two-dimensional image by scanning the lens. (2) To apply the QELS technique more widely (e.g. the samples whose one phase is turbid, liquid metal), we adopted reflective configuration. As a consequence, we succeed to develop the instrument and have applied to scientifically and industrially interesting systems as follows. (1) The dynamic molecular behavior of a phase transfer catalytic reaction at a liquid/liquid interfaces. (2) The dynamic molecular behavior of a nonlinear chemical oscillation system at water/nitrobenzene interfaces. (3) Hydrolysis reaction of phospholipid monolayer (biological membrane) by phospholipase A2 at oil/water interface. We also succeeded to improve time resolution from second to millisecond order by using new data sampling device with efficient time resolution. This improvement opens the way to monitor chemical reactions and corrective behavior of molecules at liquid/liquid interfaces which taking place in millisecond order.

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  • Development of picosecond AFM and its application to the surface of semiconductors

    Grant number:11555225  1999 - 2000

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B).  The University of Tokyo

    SAWADA Tsuguo, KATAYAMA Kenji, YUI Hiroharu, FUJINAMI Masanori

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    Grant amount: \13700000 ( Direct Cost: \13700000 )

    The aim of this research project is to develop the time-resolved scanning probe microscope (SPM) and to apply it to the surface of semiconductors. To achieve the picosecond time-resolved measurement, the combination of the pump-probe technique and SPM is required. In this project, fast thermalization process of carrier in Si has been investigated using a wavelength-selective transient reflecting grating method. Dynamics of photo-excited carriers in Si involves carrier-carrier scattering, carrier-lattice scattering, recombination, diffusion, and trap into defect energy level. By analyzing wavelengh dependency in the transient reflecting grating response, it has been found that the relaxation process in several picosecond is attributed to change in dielectric constant at the Si surface and that one in 200 picosecond to thermally process induced by photo-excited carriers. This information is very useful to investigate fast phenomena of photo-excited carriers at the Si surface.
    To combine the pump-probe methods with SPM, scanning near-field optical microscope (SNOM) with the fiber probe was chosen. We have realized the measurement of photothermal effect in SNOM configuration. The introduction of pump laser to the sample was used the evanescent light from the fiber probe. And then the absorption of light induced the change of refractive index, or the thermal lens, which was detected by deflection of probe laser. In this work, the dye molecules were excited by 532nm pump laser emitted from the fiber probe, and the thermal lens induced were detected by the 633nm probe laser transmitted from the fiber one. This is the first time to detect the thermal lens by evanescent excitation in SNOM configuration. We have a plan to develop the picosecond time-resolved SNOM to detect the photothremal phenomena by introducing the pulse laser to the fiber probe and to apply it to the surface in semiconductors.

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  • Positron annihilation spectroscopy in behavior of defects by chemical analysis of nano-space in solids

    Grant number:11450321  1999 - 2000

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B).  The University of Tokyo

    FUJINAMI Masanori, KATAYAMA Kenji, YUI Hiroharu, SAWADA Tsuguo

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    Grant amount: \13200000 ( Direct Cost: \13200000 )

    The aim of this research project is to clarify the chemical state of vacancy-impurity complex defects, or nano-space, in solids. We have developed a coincidence Doppler broadening(CDB)method in positron annihilation spectroscopy. The positrons trapped at V-I complexes annihilate electrons due to impurity. Annihilation with core electrons gives larger Doppler shifts compared with valence electrons, so that it is possible to identify the impurity by analyzing the high electron momentum region. The CDB method improves the peak to background ratio in the annihilation spectrum to around 10^5 and fine structures due to core electrons from impurity atom can be discussed. In this project, the defects in Si implanted with various kinds of ions have been investigated.
    Firstly, it is found that the CDB spectrum for Si ion implanted Si is appropriate as the reference for the defect study in Si. Some characteristic structures due to V-O, V-F and V-H complexes appear in high momentum region in the CDB spectra. From the CDB spectra and positron lifetime, the defect behavior has been considered. For example, the defect induced by O implantation to Si is identified as V_3O, which is transformed into V_6O_2 in annealing at 600°C.An anneal at 800°C results in formation of V_<10>O_6.
    Further, we have studied the defects in Fe implanted with Cu ions. Simple vacancy-type defects are observed in the surface layer of the sample implanted with less than 5x10^<14>/cm^2, while it has been found that in 5x10^<15>/cm^2, the inner wall of voids is covered with Cu atoms. Combined with the positron lifetime measurement, CDB technique becomes a powerful tool for investigating the defect structure, especially vacancy-impurity complexes.

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  • Nano-Chemistry in Liquid by Photothermal Spectroscopy

    Grant number:10305063  1998 - 1999

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)  The University of Tokyo

    SAWADA Tsuguo, YUI Hiroharu, FUJINAMI Masanori, KITAMOARI Takehiko, KATAYAMA Kenji

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    Grant amount: \32500000 ( Direct Cost: \32500000 )

    We have developed several analytical methods in order to clarify chemical phenomena in nanospace in liquid phase and shown their usefulness in this project. In highly sensitive molecular- detection in liquid nanospace, the thermal lens microscope using photothermal effects was evolved and optimized for practical applications. The photothermal signal intensity was estimated more precisely to consider the surface morphology in samples, so that we succeeded in the analysis of the antigen-antibody reactions on the cell. Further, to apply this method to monitor the chelating reaction in the 250μm width channel, we could first integrate the flow injection analysis on the glass chip. Next, we have advanced the quasi-elastic laser scattering method which can monitor the number of molecules at liquid/liquid interface, and the molecular transfer and the reaction were studied in situ. New result have been obtained on the transfer of various surfactants at the interface, the interfacial behavior of phase transfer catalysis, and the hydrolysis of DPPC by a hydrolysis enzyme.
    Ultra fast lens effect method using femtosecond pulse laser has been developed to clarify the energy transfer mechanism from solute to solvent in liquid and the solute-solvent effect, has studied in photo-excited molecular motion and reaction. In the molecular dynamics of Auramin O in low-viscosity solutions, the fast relaxation process within several ps was found out and it was found that the relaxation time depended on the mean molecular weight of solvent. In photo isomerization of amino azobenzen, the solvent dependence on the relaxation process in the intermediated state was firstly measured.
    It has been founded as the novel phenomena in the liquid nanospace that the stimulated Raman scattering in laser breakdown induced plasma was emitted in the very early stage within several tens seconds. The Raman spectra obtained were characteristic and we have investigated it as the new structural analysis method in liquid.
    The above-mentioned analytical methods, which are based on the photothermal effect and capillary wave, are applicable for non-fluorescent molecules and their sensitivity is comparable to the fluorescent methods. It is, therefore, concluded that new nano-chemistry world in liquid is opened by them

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Intellectual property rights

  • 顕微鏡

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    Application no:特願2019-034641  Date applied:2019.2.27

    Announcement no:特開2020-140037  Date announced:2020.9.3

    Applicant (Organization):学校法人中央大学

  • 無動力式循環型酸化還元方法およびその装置

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    Application no:特願2012-083994  Date applied:2012.4.2

    Announcement no:特開2013-212460  Date announced:2013.10.17

    Applicant (Organization):学校法人中央大学

  • 半導体における多重励起子生成状態の評価方法

    沈 青,豊田 太郎

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    Application no:特願2011-36258  Date applied:2011.2.22

    Announcement no:特開2012-173171  Date announced:2012.9.10

    Applicant (Organization):学校法人中央大学、国立大学法人電気通信大学

  • ナノ粒子の粒径測定装置及びナノ粒子の粒径測定方法

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    Application no:特願2009-093541  Date applied:2009.4.8

    Announcement no:特開2010-243374  Date announced:2010.10.28

    Applicant (Organization):学校法人中央大学

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  • 2023   先端科学技術論Ⅰ   Department

  • 2023   光機能化学   Department

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  • 2023   応用化学特殊論文研修Ⅰ   Graduate school

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  • 2023   応用化学特論   Graduate school

  • 2023   応用化学論文研修第一   Graduate school

  • 2023   応用化学論文研修第三   Graduate school

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  • 2023   理工学英語セミナーⅠ   Graduate school

  • 2023   理工学英語セミナーⅡ   Graduate school

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