Updated on 2024/03/28

写真a

 
IMURA, Kohei
 
Affiliation
Faculty of Science and Engineering, School of Advanced Science and Engineering
Job title
Professor
Degree
博士(理学) ( 大阪大学 )

Committee Memberships

  • 2020.09
    -
    Now

    分子科学会  幹事

  • 2014
    -
    Now

    日本分光学会代議員

  • 2016.04
    -
    2018.03

    応用物理学会代議員

  • 2016.04
    -
    2018.03

    日本化学会物理化学ディビジョン幹事

  • 2016.04
    -
     

    日本化学会講演企画小委員会委員

  • 2014.01
    -
    2014.12

    日本化学会グランプリ小委員会委員長

  • 2012.04
    -
    2013.03

    光科学異分野横断萌芽研究会代表世話人

  • 2010.04
    -
    2012.03

    光科学異分野横断萌芽研究会化学分野幹事

  • 2009
    -
     

    日本分光学会 ナノ分光部会  幹事

  •  
     
     

    日本分光学会企画委員会常務委員

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Professional Memberships

  •  
     
     

    JAPAN SOCIETY FOR MOLECULAR SCIENCE

  •  
     
     

    Society of Nano Science and Technology

  •  
     
     

    THE JAPAN SOCIETY OF APPLIED PHYSICS

  •  
     
     

    THE SPECTROSCOPICAL SOCIETY OF JAPAN

  •  
     
     

    THE CHEMICAL SOCIETY OF JAPAN

  •  
     
     

    Optical Society of America

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Research Areas

  • Fundamental physical chemistry / Nanometer-scale chemistry

Research Interests

  • 近接場光学・プラズモン・分子分光学・超高速分解分光・表面増強ラマン散乱・コロイド・クラスター化学・分子衝突・軌道間相互作用・気相分子衝突動力学

Awards

  • 日本学術振興会特別研究員等審査会専門委員表彰

    2013.07  

    Winner: 井村 考平

  • 文部科学大臣表彰若手科学者賞

    2012.04  

    Winner: 井村 考平

  • 日本分光学会奨励賞

    2007.11  

  • 光科学技術研究振興財団 研究表彰

    2007.03  

  • 日本化学会進歩賞

    2007.03  

  • 分子構造総合討論会奨励賞

    2005.09  

▼display all

 

Papers

  • Nanoantenna Effect at the Center of the Bull’s Eye Pattern by Controlling the Refractive Indices and Layer Thicknesses of Dielectric Media on a Silver Surface

    Keiko Tawa, Takeha Shinohara, Yasunori Nawa, Seiju Hasegawa, Kohei Imura

    The Journal of Physical Chemistry C   128 ( 7 ) 3011 - 3018  2024.02

    DOI

    Scopus

  • Selective Excitation of Dark Plasmon Modes Using Cylindrical Vector Beams Studied by Microscopic Imaging of Nonlinear Photoluminescence

    Seiju Hasegawa, Honoka Ichikawa, Kohei Imura

    The Journal of Physical Chemistry C   128 ( 6 ) 2536 - 2542  2024.02

    DOI

    Scopus

  • Optical properties of multilayer MoS<inf>2</inf> modified with thermal and shape transformation by laser irradiation

    Shun Ogata, Kohei Imura

    Chemical Physics Letters   831  2023.11

     View Summary

    In this study, the optical properties of multilayer MoS2 at various temperatures and incident powers were studied. The multilayer MoS2 exhibits two excitonic bands and an indirect band gap transition. We found from the incident power dependence of photoluminescence that the bands exhibit a redshift with increasing incident power. For high-power excitation, a new band emerges near the indirect band and intensity ratio between the excitonic band and indirect band shows peculiar incident power dependence. We conclude that the emergence of a new band and incident power-dependent intensity ratio originate from the elevation of temperature and the morphological change, respectively.

    DOI

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  • Nanoscopic Imaging of Photonic Modes Excited in Square-Shaped Perylene Microcrystals

    Keisuke Imaeda, Kohei Imura

    The Journal of Physical Chemistry C   127 ( 9 ) 4665 - 4671  2023.03  [Refereed]

    DOI

    Scopus

  • Nonlinear Photoluminescence from Gold Nanoparticle Thin Films Studied by Scanning Near-Field Optical Microscopy

    Atsuko Jimbo, Kohei Imura

    The Journal of Physical Chemistry C   126 ( 35 ) 14960 - 14966  2022.08  [Refereed]

    DOI

    Scopus

    2
    Citation
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  • Photoluminescence Properties of Gold Nanorod and J-Aggregate Hybrid Systems Studied by Scanning Near-Field Optical Microscopy

    Seiju Hasegawa, Kohei Imura

    The Journal of Physical Chemistry C   126 ( 13 ) 5944 - 5949  2022.04  [Refereed]

    DOI

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    3
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  • Nanoantenna effect dependent on the center structure of Bull’s eye-type plasmonic chip

    Tomoya Nagasue, Takeha Shinohara, Seiju Hasegawa, Kohei Imura, Keiko Tawa

    Optics Express   30 ( 5 ) 7526 - 7526  2022.02  [Refereed]

     View Summary

    A bright spot is observable in the center of Bull's eye plasmonic pattern with a fluorescence microscope due to the plasmonic nanoantenna effect. In this effect, a propagating wave of surface plasmon resonance concentrates in the center. This study focused on the relationship between the center structure of Bull's eye pattern and the nanoantenna effect in four fabricated Bull's eye-type plasmonic chips with centers of different sizes (full- or half-pitch diameter) and shapes (convex or concave). The fluorescence intensity of the fluorescent nanoparticles adsorbed to these plasmonic chips was measured with an upright-inverted microscope to evaluate the plasmonic chip enhancement factor composed of the product of the excitation and emission enhancement and individual factors. When the emission enhancement factor was investigated under nonresonance excitation conditions, by the disappearance of a bright spot, excitation enhancement was found to contribute to the plasmonic nanoantenna effect. The concave Bull's eye structure with a half-pitch diameter demonstrates the highest nanoantenna effect due to the formation of a larger constructive wave in the superposition of the diffraction wave of incident light under resonance conditions. In addition, the electromagnetic field intensity simulated by discrete dipole approximation agrees with the microscopy results. Overall, the results indicate that the plasmonic nanoantenna effect could be controlled depending on the resonance condition and center structure. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

    DOI

  • Observation of the plasmon mode transition from triangular to hexagonal nanoplates

    Keisuke Imaeda, Seiju Hasegawa, Kohei Imura

    The Journal of Chemical Physics   156 ( 4 ) 044702 - 044702  2022.01  [Refereed]

     View Summary

    The geometrical shape of a metal nanostructure plays an essential role in determining the optical functionality of plasmonic cavity modes. Here, we investigate the geometrical modification effect on plasmonic cavity modes induced in two-dimensional gold nanoplates. We perform near-field transmission measurements on triangular and tip-truncated triangular nanoplates and reveal that the plasmonic cavity modes are qualitatively consistent with each other as long as the snipping size is not significant. To elucidate the tip-truncation effect on plasmonic cavity modes in detail, we carry out numerical simulations for nanoplates with various snipping sizes and find that tip truncation affects not only the optical selection rules but also the energy relation for the plasmonic cavity modes. These findings provide a foundation for the rational design of plasmonic cavities with desired optical functionality.

    DOI

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    2
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  • Visualization of Plasmon–Exciton Interactions by Scanning Near-Field Optical Microscopy

    Asami Yokozawa, Seiju Hasegawa, Keisuke Imaeda, Kohei Imura

    The Journal of Physical Chemistry C   125 ( 44 ) 24515 - 24520  2021.11  [Refereed]

     View Summary

    The electronic properties of a substance are perturbed by interactions of elementary excitations. The optical properties of the interacting states have been extensively studied and revealed to be correlated with the eigenfunctions of the isolated systems. On the other hand, the spatial characteristics of the states have been little studied because of the diffraction limit of light. In this study, we examine plasmon and exciton interactions in silver nanoplate and organic J-aggregate hybrid structures using scanning near-field optical microscopy. We reveal that the light transmission is enhanced when the plasmon and exciton resonantly interact with each other. We visualize the spatial distribution of the interacting states and find that the interaction of the high-order plasmons with the exciton enables manipulation of the electronic states in a spatially resolved manner. This study demonstrates that the optical field can be spatially controlled via coupling of the elementary excitations.

    DOI

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    4
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  • Plasmon-Enhanced Fluorescence near Single Gold Nanoplates Studied by Scanning Near-Field Two-Photon Excitation Microscopy

    Seiju Hasegawa, Keisuke Imaeda, Kohei Imura

    Journal of Physical Chemistry C   125 ( 38 ) 21070 - 21076  2021.09  [Refereed]

     View Summary

    Plasmonic optical fields have been applied for surface-enhanced spectroscopy, chemical sensing, and bioimaging. Spatial distributions of optical fields are critical for optimizing their functionalities. In plasmon-enhanced fluorescence, both incoming and outgoing fields excited by the plasmon should contribute to the enhancement of the fluorescence. Spatial characteristics of plasmons are critical not only for the fundamental understanding of the plasmon but also for their practical applications. Here, we investigate the spatial characteristics of the excitation and relaxation processes near the gold nanoplate using time-resolved near-field two-photon microscopy. We reveal from near-field optical microscopy that the incident field is locally enhanced by the plasmon resonance effect and the lightning rod effect. Near-field time-resolved fluorescence imaging demonstrates that the fluorescence decay is accelerated entirely over the surface of the plate regardless of the spatial distribution of the incident field. These results provide deep insight into plasmonic optical fields and are of great importance for designing plasmon-based substrates for surface-enhanced spectroscopy and photochemical reactions.

    DOI

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    4
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  • Optical field and chemical environment near the surface modified gold nanoparticle assembly revealed by two-photon induced photoluminescence and surface enhanced raman scattering

    Atsuko Jimbo, Yui Nishikado, Kohei Imura

    Bulletin of the Chemical Society of Japan   94 ( 9 ) 2272 - 2278  2021  [Refereed]

     View Summary

    Gold nanoparticle assemblies significantly enhance optical fields and have been applied for nano-optical devices, biosensing, and chemical reactions. The optical properties of the assembly are, however, less controllable once the assemblies are fabricated on a solid substrate. An assembly prepared at the water-organic solvent interface overcomes this restriction and provides flexible photochemical reaction fields. Additionally, the physical and chemical properties of the assembly can be controlled by modification of the nanoparticle surface. In this study, we investigated the optical properties of the assembly using two-photon-induced photoluminescence and surface-enhanced Raman scattering, and demonstrated that the optical field enhancement and chemical environment near the gold nanoparticle assembly can be finely controlled by surface-modification of the gold nanoparticles.

    DOI

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    6
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  • Photoluminescence from Carbon Dot-Gold Nanoparticle Composites Enhanced by Photonic and Plasmonic Double-Resonant Effects

    Yoshio Kamura, Kohei Imura

    ACS Omega   5 ( 45 ) 29068 - 29072  2020.11  [Refereed]

     View Summary

    Carbon dots (CDs) exhibit chemical stability and low toxicity, so they are promising for biomedical and imaging applications. The quantum yield of the photoluminescence is typically 10-20%, which limits practical applications. We fabricate carbon dot-gold nanoparticle photonic crystals (CD-GNP PCs) and demonstrate enhanced photoluminescence intensity from the carbon dots using the photonic and plasmonic double-resonant effects. A severalfold enhancement was obtained compared to the neat CD. The method developed in this study provides a universal scheme to enhance light-emitting materials, which is promising for the development of ultrahigh molecular sensing and bioimaging techniques.

    DOI

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    7
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  • Near-field transmission and reflection spectroscopy for revealing absorption and scattering characteristics of single silver nanoplates

    Hidetoshi Mizobata, Seiju Hasegawa, Mamoru Tamura, Takuya Iida, Kohei Imura

    Journal of Chemical Physics   153 ( 14 )  2020.10  [Refereed]

     View Summary

    Near-field optical microscopy visualizes spatial characteristics of elementary excitations induced in metal nanostructures. However, the microscopy is not able to reveal the absorption and scattering characteristics of the object simultaneously. In this study, we demonstrate a method for revealing the absorption and scattering characteristics of silver nanoplate by using near-field transmission and reflection spectroscopy. Near-field transmission and reflection images show characteristic spatial features attributable to the excited plasmon modes. The near-field refection image near the resonance shows a reversed contrast depending on the observed wavelength. Near-field reflection spectra show unique positive and negative resonant features. We reveal that the optical characteristics and the wavelength dependency of the optical contrast originate from the scattering and absorption properties of the plasmons, with the aid of the electromagnetic simulations.

    DOI PubMed

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  • Enhanced and Polarized Photoluminescence from Carbon Dot-Metal Nanoparticle Composites

    Yoshio Kamura, Kohei Imura

    Journal of Physical Chemistry C   124 ( 13 ) 7370 - 7377  2020.04  [Refereed]

     View Summary

    Carbon dots are attracting much attention because of their low toxicity, biocompatibility, and photostability. In this study, we fabricate carbon dot-metal nanoparticle composites using electron-beam-induced chemical reactions to improve the photoluminescence characteristics. We investigate the spectral characteristics of the composites by linear and nonlinear optical spectroscopy. The composites show plasmon resonance depending on the material used. The linear and nonlinear photoluminescence from the composites are enhanced by plasmon excitations, and the enhancement reaches nearly several times and 20 times, respectively. We also fabricate nanowire structures containing the composites. The structures show very intense photoluminescence and unique polarization characteristics depending on the wire width. We reveal that the polarization characteristics originate from the plasmonic coupling along the short axis of the wire. The technique developed in this study is promising for the polarization control of light-emitting elements and the creation of new functional nanomaterials.

    DOI

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    8
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  • Spatial characteristics of optical fields near a gold nanorod revealed by three-dimensional scanning near-field optical microscopy

    Hiromasa Suzuki, Keisuke Imaeda, Hidetoshi Mizobata, Kohei Imura

    Journal of Chemical Physics   152 ( 1 )  2020.01  [Refereed]

     View Summary

    We visualize plasmon mode patterns induced in a single gold nanorod by three-dimensional scanning near-field optical microscopy. From the near-field transmission imaging, we find that 3rd and 4th order plasmon modes are resonantly excited in the nanorod. We perform electromagnetic simulations based on the discrete dipole approximation method under focused Gaussian beam illumination and demonstrate that the observed near-field spectral and spatial features are well reproduced by the simulation. We also reveal from the three-dimensional near-field microscopy that the 4th order plasmon mode confines optical fields more tightly compared with the 3rd order mode. This result indicates that the even-order plasmon modes are promising for enhancing the light-matter interactions.

    DOI PubMed

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  • Nanoscopic Visualization of Fluorescence Excitation Probability on Two-Dimensional Periodical Gold Nanohole Array

    K. Imaeda, K. Tawa, K. Imura

      48   1119 - 1121  2019.06  [Refereed]

    DOI

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    2
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  • Direct Visualization of Near-Field Distributions on a Two-Dimensional Plasmonic Chip by Scanning Near-Field Optical Microscopy

    K. Imaeda, W. Minoshima, K. Tawa, K. Imura

    J. Phys. Chem. C   123   10529 - 10535  2019.04  [Refereed]

    DOI

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    7
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  • Plasmon enhanced optical responses of diarylethene molecules adsorbed on gold nanorods

    S. Noda, S. Hasegawa, H. Hamada, S. Kobatake, K. Imura

    CHEMISTRY LETTERS   48 ( 6 ) 537 - 540  2019.03  [Refereed]

     View Summary

    Assemblies of gold nanorods capped with poly-diarylethene (DE) were chemically prepared in a solution. Plasmon assisted optical responses of the poly(DE) have been studied. Fluorescence from the open-form of DE was mostly quenched near 550nm due to interband transition of gold, while fluorescence near 700nm was slightly enhanced by the longitudinal plasmon resonance. Cycloreversion reaction of the gold nanorodpoly(DE) has been also studied, and it has been found that the reaction rate is enhanced by the plasmon excitation and increases nearly two-fold in the assembly. The magnitude of the enhancement is qualitatively consistent with the spatially and orientationally averaged value of the simulated optical field enhancements in the vicinity of the nanorod.

    DOI

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    6
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  • Space-Selective Fabrication of Light Emitting Carbon Dots in Polymer Films Using Electron-Beam-Induced Chemical Reactions

    Y. Kamura, K. Imura

      4   3380  2019.02  [Refereed]

    DOI

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    5
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  • Characterization of Overlapped Plasmon Modes in Gold Hexagonal Plate Revealed by Three-Dimensional Near-Field Optical Microscopy

    T. Matsuura, K. Imaeda, S. Hasegawa, H. Suzuki, K. Imura

    J. Phys. Chem. Lett.   10 ( 4 ) 819 - 824  2019.01  [Refereed]

     View Summary

    A detailed characterization of plasmon modes is important not only for a deeper understanding of plasmons but also for their practical applications. In this study, we investigated the three-dimensional near-field characteristics of high-order plasmon modes excited in a gold hexagonal nanoplate. From the near-field spectroscopic images, we found that both in-plane and out-of-plane plasmon modes observed near 900 nm were spectrally and spatially overlapped. We performed three-dimensional near-field measurement to reveal the optical characteristics of the overlapped modes in detail. We found that the steric near-field distribution near the nanoplate strongly depended on the plasmon mode, and the out-of-plane mode confines electromagnetic fields more tightly than the in-plane mode. We also found that the in-plane mode was dominantly visualized as the probe tip-sample distance increased. These findings demonstrate that the three-dimensional near-field technique enables selective visualization of a single plasmon mode even if multiple modes are spatially and spectrally overlapped.

    DOI

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    18
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  • Static and Dynamic Near-Field Measurements of High-Order Plasmon Modes Induced in a Gold Triangular Nanoplate

    Imaeda Keisuke, Hasegawa Seiju, Imura Kohei

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   9 ( 14 ) 4075 - 4081  2018.07  [Refereed]

     View Summary

    Precise understanding of the spatiotemporal characteristics of plasmons is essential for the development of applications of plasmonic nanoparticles. In this study, we investigated the spatiotemporal properties of high-order plasmon modes induced in a gold triangular nanoplate by static and dynamic near-field measurements. The near-field transmission measurements revealed that in-plane and out-of-plane polarized plasmon modes were simultaneously excited and these modes spectroscopically and spatially overlapped. The superposition of these modes was visualized in the near-field two-photon excitation image of the nanoplate. We performed time-resolved autocorrelation measurements on the nanoplate and found that the correlation width was broader than the excitation pulse due to the plasmon dephasing process. From the correlation width map of the nanoplate, we experimentally demonstrated that the out-of-plane plasmon mode exhibits a longer dephasing time than the in-plane plasmon mode. These findings indicate that the out of -plane mode is desirable for improving the performance of plasmons in various applications.

    DOI PubMed

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    18
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  • Fabrication method of two-photon luminescent organic nano-architectures using electron-beam irradiation

    Yoshio Kamura, Kohei Imura

    Applied Physics Letters   112 ( 24 )  2018.06  [Refereed]

     View Summary

    Optical recording on organic thin films with a high spatial resolution is promising for high-density optical memories, optical computing, and security systems. The spatial resolution of the optical recording is limited by the diffraction of light. Electrons can be focused to a nanometer-sized spot, providing the potential for achieving better resolution. In conventional electron-beam lithography, however, optical tuning of the fabricated structures is limited mostly to metals and semiconductors rather than organic materials. In this article, we report a fabrication method of luminescent organic architectures using a focused electron beam. We optimized the fabrication conditions of the electron beam to generate chemical species showing visible photoluminescence via two-photon near-infrared excitations. We utilized this fabrication method to draw nanoscale optical architectures on a polystyrene thin film.

    DOI

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  • Gold Ultrathin Nanorods with Controlled Aspect Ratios and Surface Modifications: Formation Mechanism and Localized Surface Plasmon Resonance

    Ryo Takahata, Seiji Yamazoe, Kiichirou Koyasu, Kohei Imura, Tatsuya Tsukuda

    Journal of the American Chemical Society   140 ( 21 ) 6640 - 6647  2018.05  [Refereed]

     View Summary

    © 2018 American Chemical Society. We synthesized gold ultrathin nanorods (AuUNRs) by slow reductions of gold(I) in the presence of oleylamine (OA) as a surfactant. Transmission electron microscopy revealed that the lengths of AuUNRs were tuned in the range of 5-20 nm while keeping the diameter constant (∼2 nm) by changing the relative concentration of OA and Au(I). It is proposed on the basis of time-resolved optical spectroscopy that AuUNRs are formed via the formation of small (<2 nm) Au spherical clusters followed by their one-dimensional attachment in OA micelles. The surfactant OA on AuUNRs was successfully replaced with glutathionate or dodecanethiolate by the ligand exchange approach. Optical extinction spectroscopy on a series of AuUNRs with different aspect ratios (ARs) revealed a single intense extinction band in the near-IR (NIR) region due to the longitudinal localized surface plasmon resonance (LSPR), the peak position of which is red-shifted with the AR. The NIR bands of AuUNRs with AR < 5 were blue-shifted upon the ligand exchange from OA to thiolates, in sharp contrast to the red shift observed in the conventional Au nanorods and nanospheres (diameter >10 nm). This behavior suggests that the NIR bands of thiolate-protected AuUNRs with AR < 5 are not plasmonic in nature, but are associated with a single-electron excitation between quantized states. The LSPR band was attenuated by thiolate passivation that can be explained by the direct decay of plasmons into an interfacial charge transfer state (chemical interface damping). The LSPR wavelengths of AuUNRs are remarkably longer than those of the conventional AuNRs with the same AR, demonstrating that the miniaturization of the diameter to below ∼2 nm significantly affects the optical response. The red shift of the LSPR band can be ascribed to the increase in the effective mass of electrons in AuUNRs.

    DOI PubMed

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  • Imaging of Plasmonic Eigen Modes in Gold Triangular Mesoplates by Near-Field Optical Microscopy

    Keisuke Imaeda, Seiju Hasegawa, Kohei Imura

    Journal of Physical Chemistry C   122 ( 13 ) 7399 - 7409  2018.04  [Refereed]

     View Summary

    We investigated the spectral and spatial characteristics of plasmons induced in chemically synthesized triangular gold nano- and microplates by aperture-type scanning near-field optical microscopy. Near-field transmission images taken at plasmon resonance wavelengths showed two-dimensional oscillating patterns inside the plates. These spatial features were well reproduced by the square moduli of calculated eigen functions confined in the two-dimensional triangular potential well. From the irreducible representations of the eigen functions, it was found that both the out-of-plane modes and in-plane modes were clearly visualized in the near-field images. We compared near-field transmission images of a triangular nanoplate to those of a truncated one with a similar dimension and revealed that the fine details of the geometrical shape of the apex on the plate strongly influence the experimentally observed eigen mode structures. We also performed near-field transmission measurements of micrometer-scale triangular plates and found that wavy patterns were observed along the edges of the plates. The wavy features can be interpreted as the superposition of eigen modes with similar eigen energy. These findings prove that near-field transmission imaging enables one to directly visualize plasmonic eigen modes confined in the particle and provide fruitful information not only for a deeper understanding of plasmons but also for the application of the design and active control of plasmonic optical fields.

    DOI

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    25
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  • 金属ナノプレートの分光特性とプラズモンモード

    井村 考平

    C & I commun : colloid & interface communication : newsletter from DCSC   43 ( 2 ) 26 - 28  2018  [Refereed]

    CiNii

  • Development of Aperture-Type Near-Field Reflection Spectroscopy and Its Application to Single Silver Nanoplates

    Hidetoshi Mizobata, Seiju Hasegawa, Kohei Imura

    JOURNAL OF PHYSICAL CHEMISTRY C   121 ( 21 ) 11733 - 11738  2017.06  [Refereed]

     View Summary

    We developed an aperture-type near-field reflection spectral imaging method to obtain optical properties of materials with a nanometer spatial resolution. We adopted a phase-stepping technique to extract genuine near-field signals of a sample from the observed intensity spectra dominated by the large background, in a multiplex manner. We performed near-field reflection spectral imaging of a single silver nanoplate to evaluate the developed system and also to examine near-field optical properties of the nanoplate. The near-field reflection spectrum of the nanoplate shows multiple resonant features that are not observable by conventional methods. The near-field reflection image taken at the resonance shows unique spatial features attributable to the plasmon mode resonantly excited. The developed system is applicable to transparent samples as well as opaque ones and enables spectral as well as spatial characteristics of the samples to be revealed.

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  • Near-field spectroscopic properties of complementary gold nanostructures: applicability of Babinet's principle in the optical region

    Hidetoshi Mizobata, Kosei Ueno, Hiroaki Misawa, Hiromi Okamoto, Kohei Imura

    OPTICS EXPRESS   25 ( 5 ) 5279 - 5289  2017.03  [Refereed]

     View Summary

    We examine the far-field and near-field properties of complementary screens made of nanostructured gold thin films, a rectangular nanowire and a nanovoid, using an aperture-type scanning near-field optical microscope and electromagnetic field calculations, and discuss the applicability of Babinet's principle in the optical region. The far-field transmission spectra of the complementary screens are considerably different from each other. On the other hand, genuine near-field extinction spectra exhibit nearly complementary characteristics. The spatial features of the observed near-field images for the complementary screens show little correlation. We have found from the Fourier analysis of the simulated images that high spatial-frequency components of the electromagnetic fields show mutual spatial correlation. These results suggest that Babinet's principle is applicable to the high spatial-frequency components of electromagnetic fields for the complementary screens. (C) 2017 Optical Society of America

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  • Interstitial-Dependent Enhanced Photoluminescence: A Near-Field Microscopy on Single Spheroid to Dimer, Tetramer, and Few Particles Gold Nanoassembly

    Mohammad Kamal Hossain, Masahiro Kitajima, Kohei Imura, Hiromi Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY C   121 ( 4 ) 2344 - 2354  2017.02  [Refereed]

     View Summary

    Interstitials to be active or inactive depend on the characteristics of nanoaggregate. In this perspective, near-field scanning optical microscopy has been utilized to probe well-defined monomer, dimer, tetramer, and small assembly of gold nanoparticles of 60 nm diameter with spatial resolution of similar to 35 nm. Confinement of localized surface plasmon resonances (LSPRs)-mediated near electromagnetic (EM) field distribution was observed through two-photon induced photoluminescence (TPI-PL) since TPI-PL emission is proportional to the fourth power of induced EM-field. It was revealed that the intensity of TPI-PL observed in closely connected nanoparticles was very strong with reference to those obtained in the presence of isolated nanoparticles of the same size. Among the closely connected nanoparticles, interparticle gap and interparticle axes played a vital role in TPI-PL emission enhancement, as was evident and observed directly through TPI-PL intensity distribution. Correlated local geometry and emission distribution confirmed that interstitials along the active interparticle axes exhibits confined and enhanced TPI-PL emission. The emission intensity for dimers was found higher than that of tetramer of gold nanoparticles. In case of small assembly of the same gold nanoparticles, intensity was observed to be the highest of all along with wider full width at half-maximum of 188.09 nm, more than double of those obtained at dimers and tetramer. The observations were further demonstrated as a function of EM near-field distribution, as it is well-known that TPI-PL emission is enhanced by LSPRs-assisted EM-field localization. Model systems were designed along with geometries and parameters very similar to those under investigation. Finite-difference time-domain analysis was carried out to deduce near EM field distributions at various deterministic factors such as size, interparticle gap, incident polarization, etc. A plausible explanation of enhanced and confined TPI-PL emissions in archetype interstitials of well-known plasmonic systems was highlighted.

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  • Photobleaching-Assisted Near-Field Absorption Spectroscopy: Its Application to Single Tubular J-Aggregates

    Kohei Imura, Hidetoshi Mizobata, Yoshihiko Makita

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   89 ( 12 ) 1518 - 1522  2016.12  [Refereed]

     View Summary

    We propose photobleaching-assisted near-field optical spectroscopy to obtain the absorption properties of nanomaterials. We used bis(3-sulfopropyl)-5,5', 6,6'-tetrachloro-11'-dioctyl-benzimidacarbocyanine (C8S3) double-wall tubular J-aggregates for demonstrating this method. We photobleached the J-aggregate by photoirradiation. We obtained the absorption spectrum of the J-aggregates by subtracting the transmission spectra observed before and after the photobleaching. The spectrum showed an intense asymmetric peak near 595 nm, which was assigned to the J-bands. These features were well reproduced by theoretical model calculations. We estimated the oscillator strength per molecule from the observed absorbance, and we found that the determined oscillator strength is comparable to that of the monomer. These results indicate that the proposed method is applicable for obtaining near-field absorption spectra of nanomaterials in a semi-quantitative manner.

    DOI CiNii

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  • Multiple Resonances Induced by Plasmonic Coupling between Gold Nanoparticle Trimers and Hexagonal Assembly of Gold-Coated Polystyrene Microspheres

    Takako Uchida, Takayasu Yoshikawa, Mamoru Tamura, Takuya Iida, Kohei Imura

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   7 ( 18 ) 3652 - 3658  2016.09  [Refereed]

     View Summary

    Optical properties of a gold nanoparticle trimer assembly coupled with gold-coated hexagonally close-packed polystyrene microspheres were investigated by linear and nonlinear spectroscopy. The observed reflection spectrum shows multiple peaks from the visible to near-infrared spectral regions. The spectroscopic properties were also examined by a finite-difference time-domain simulation. We found that the optical response of plasmons excited in the gold nanoparticle trimers was significantly modulated by strong coupling of the plasmons and the photonic mode induced in the gold-coated polystyrene assembly. Two-photon induced photoluminescence and Raman scattering from the sample were investigated, and both signals were significantly enhanced at the gold nanoparticle assembly. The simulations reveal that the electric fields can be enhanced site-selectively, not only at the interstitial sites in the nanoparticle assembly but also at the gaps between the particle and the gold film due to plasmonic interactions, by tuning the wavelength and are responsible for the strong optical responses.

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    18
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  • Dye-assisted visualization of plasmon modes excited in single gold nanoplates

    Keisuke Imaeda, Kohei Imura

    CHEMICAL PHYSICS LETTERS   646   179 - 184  2016.02  [Refereed]

     View Summary

    We performed dye-assisted two-photon-excitation imaging of plasmon modes in single gold nanoplates using a scanning near-field optical microscope. We observed that the fluorescence from the dye molecules was excited by the two-photon process and was enhanced several-fold on the nanoplate compared to the bare substrate. Two-photon excitation images of the single nanoplate show unique spatial features that differ from the morphology of the sample. Using electromagnetic simulations, we assigned the observed spatial features to the plasmon mode resonantly excited by the dye fluorescence. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

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    8
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  • Near-field Optical Imaging of Ultrafast Dynamics in Gold Nanorods

    H. Okamoto, Y. Nishiyama, K. Imaeda, K. Imura

    2016 PROGRESS IN ELECTROMAGNETICS RESEARCH SYMPOSIUM (PIERS)     3864 - 3864  2016  [Refereed]

  • Raman activity and dynamics of plasmons on a rough gold film studied by ultrafast scanning near-field optical microscopy

    Keisuke Imaeda, Kohei Imura

    ACS Symposium Series   1246   121 - 137  2016

     View Summary

    We investigated the surface-enhanced Raman scattering activity and spatio-temporal characteristics of plasmons excited on a rough gold film using ultrafast near-field optical microscopy. Near-field nonlinear excitation images showed a number of optically amplified spots on the sample surface. Raman scattering from molecules dispersed on the sample was enhanced at the amplified fields in a space-selective manner. Time-resolved near-field measurements revealed that the dephasing time varies depending on the excited plasmon. We evaluated the resonant mode volume from the Raman signal enhancement and the dephasing time of the plasmon, and found that the volume is on the same order as the one estimated from the topography of the sample.

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    1
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  • Observation of Plasmon Wave Packet Motions via Femtosecond Time-Resolved Near-Field Imaging Techniques

    Yoshio Nishiyama, Kohei Imura, Hiromi Okamoto

    NANO LETTERS   15 ( 11 ) 7657 - 7665  2015.11  [Refereed]

     View Summary

    The generation and dynamics of plasmon wave packets in single gold nanorods were observed at a spatiotemporal scale of 100 nm and 10 fs via time-resolved near-field optical microscopy. Following simultaneous excitation of two plasmon modes of a nanorod with an ultrashort near-field pulse, a decay and revival feature of the time-resolved signal was obtained, which reflected the reciprocating motion of the wave packet. The time-resolved near-field images were also indicative of the wave packet motion. At some period of time after the excitation, the spatial features of the two modes appeared alternately, showing motion of plasmonic wave crests along the rod. The wave packet propagation was clearly demonstrated from this observation with the aid of a simulation model. The present experimental scheme opens the door to coherent control of plasmon-induced optical fields in a nanometer spatial scale and femtosecond temporal scale.

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  • Optical properties and surface-enhanced Raman scattering activity of hexagonally arranged gold nanoparticle trimers

    Takako Uchida, Yoichi Ichikawa, Kohei Imura

    CHEMICAL PHYSICS LETTERS   638   253 - 257  2015.10  [Refereed]

     View Summary

    We studied optical properties of hexagonally arranged gold nanoparticle trimer assembly using optical microscopy. We found that the scattering spectrum showed multiple resonances in the visible region. We simulated the optical properties by assuming a pair of trimers as a model structure. The simulated spectrum reproduced the resonance features observed, and were assigned to plasmon-modes excited. Surface-enhanced Raman Scattering (SERS) activity of the assembly was found to be dependent on the excitation wavelength. The highest SERS enhancement was achieved with 633 nm excitation, reaching 108. The wavelength-dependency of the activity indicates that plasmonic fields are responsible for the enhancement. (C) 2015 Elsevier B.V. All rights reserved.

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    3
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  • Plasmon Dephasing in Single Gold Nanorods Observed By Ultrafast Time-Resolved Near-Field Optical Microscopy

    Yoshio Nishiyama, Keisuke Imaeda, Kohei Imura, Hiromi Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY C   119 ( 28 ) 16215 - 16222  2015.07  [Refereed]

     View Summary

    We applied time-resolved near-field optical microscopic measurements with ultrashort light pulses of similar to 16 fs duration to observe plasmon dephasing processes in single gold nanorods. The correlation widths of the time-resolved signals obtained at each position on the nanorods were broadened compared with the autocorrelation width of the pulse because of the plasmon lifetime. The correlation width maps of the rods showed spatially oscillating patterns that look similar to the plasmon mode structures observed in the static near-field optical images. The spatial variation of the correlation widths was explained as arising from the position-dependent contribution of the resonant plasmon excitation in the time-resolved signals relative to that of the nonresonant excitation. This finding indicates that the dephasing times of the resonant plasmon modes were constant regardless of the excitation position. This result is understood to be a consequence of the spatial coherence of the plasmon mode that causes the local excitation to be immediately delocalized across the rod after irradiation. A comparison between the time-resolved signals of the inner parts and the outer parts of the nanorods suggests that the nonresonant contribution to the time-resolved signals may be driven by the lower-order plasmon modes having resonances in a much longer wavelength region.

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  • A Topography-Metrology Correlation in Nanoscale Probed by Near-Field Scanning Optical Microscopy

    Mohammad Kamal Hossain, Masahiro Kitajima, Kohei Imura, Hiromi Okamoto

    PLASMONICS   10 ( 2 ) 447 - 454  2015.04  [Refereed]

     View Summary

    Near-field scanning optical microscopy was used to probe single nanoparticles, close-packed dimer, well-defined trimeric nanoaggregate, and separated dimer of gold nanoparticles. Surface plasmon (SP)-coupled electromagnetic (EM) field confinement at interstitials was confirmed through two-photon-induced photoluminescence (TPI-PL) imaging. A fairly well correlation between topography and metrology in nanoscale was reported with sufficient high spatial resolution. A strong excitation of SP-assisted TPI-PL was observed at gold dimer and trimeric nanoaggregate, whereas single particles and separated dimer showed negligible TPI-PL excitation. A confined distribution of TPI-PL was revealed in close-packed dimer with reference to those at isolated nanoparticles and trimer. Strong optical distribution of TPI-PL was observed at trimer, but the distribution was found broadened with reference to those at dimer. A plausible explanation of such broadened distribution was interpreted as the coalescence of surface plasmon-assisted confined optical signal of TPI-PL. Such a direct and distinguished correlation between local topography and optical field distribution with high resolution is indispensable and further addition to realize surface plasmon coupling at the interstitials. Finite different time domain analysis was carried out to elucidate the results observed herein. For a small model of three nanoobjects keeping the geometry and parameters very similar to that of the close-packed trimeric nanoaggregate under investigation, multiple confined EM fields were found at the out-of-plane polarization to the interparticle axes. With the step sizes (i.e., 50 nm), these nearby localized EM near-field-mediated optical distributions open up a possibility to coalescence and thus get broadened.

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    10
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  • Local optical responses of plasmon resonances visualised by near-field optical imaging

    Hiromi Okamoto, Tetsuya Narushima, Yoshio Nishiyama, Kohei Imura

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   17 ( 9 ) 6192 - 6206  2015  [Refereed]

     View Summary

    The unique optical characteristics of noble metal nanostructures have their origin principally in surface plasmon resonances. To exploit and design the unique characteristics arising from plasmons, an investigation of optical field structures adjacent to the nanostructure is of fundamental importance. As the spatial scale of the optical field structures is essentially smaller than the radiation wavelength in resonance with the plasmon, optical imaging methods that achieve spatial resolution beyond the diffraction limit of light are necessary to visualise the fields. In this article, we review the studies of direct experimental visualisation of plasmon resonances using near-field optical microscopy. We briefly describe the method of near-field optical microscopy used to study noble metal nanoparticles and show with several typical single gold nanoparticles that the spatial features of plasmon resonances, in particular the standing wave functions of the plasmons, can be directly visualised by near-field imaging. We then describe our recent efforts to visualise ultrafast dynamics in metal nanostructures following plasmonic excitation, which are based on near-field ultrafast imaging measurements. Another notable aspect of metal nanostructures that has attracted attention recently is the chirality of plasmons. Here, we describe a method and examples of near-field optical imaging and analyses of chiral plasmons excited on metal nanostructures.

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  • Plasmon modes in single gold nanodiscs

    K. Imura, K. Ueno, H. Misawa, H. Okamoto, D. McArthur, B. Hourahine, F. Papoff

    OPTICS EXPRESS   22 ( 10 ) 12189 - 12199  2014.05

     View Summary

    Optical properties of single gold nanodiscs were studied by scanning near-field optical microscopy. Near-field transmission spectra of a single nanodisc exhibited multiple plasmon resonances in the visible to near-infrared region. Near-field transmission images observed at these resonance wavelengths show wavy spatial features depending on the wavelength of observation. To clarify physical pictures of the images, theoretical simulations based on spatial correlation between electromagnetic fundamental modes inside and outside of the disc were performed. Simulated images reproduced the observed spatial structures excited in the disc. Mode-analysis of the simulated images indicates that the spatial features observed in the transmission images originate mainly from a few fundamental plasmon modes of the disc. (C) 2014 Optical Society of America

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  • Near-field scanning optical microscopy: Single channel imaging of selected gold nanoparticles through two photon induced photoluminescence

    Mohammad Kamal Hossain, Masahiro Kitajima, Kohei Imura, Hiromi Okamoto

    Advanced Materials Research   938   118 - 122  2014

     View Summary

    Near-field scanning optical microscopy (NSOM) is known to be a technique of choice to investigate nanometric materials and their properties beyond far-field diffraction limit resulting high spatial, spectral and temporal resolution. Here in this report, a state of art facility, aperture-NSOM was used to probe single nanoparticle, dimer, trimer and small nanoaggregate of gold nanoparticles. Shear force topography and two photon induced photoluminescence (TPI-PL) images captured simultaneously by the system facilitated to clarify the correlation between the local geometry and the emitted photon of TPI-PL. Small gold aggregates including trimer showed strong optical confinement of TPI-PL with reference to that of single gold nanoparticles. It was also evident that the interparticle gap does have a great influence in localized electromagnetic (EM) field mediated optical confinement of TPI-PL. Such observations were also supported by finite different time domain (FDTD) analysis keeping the simulation parameter nearly identical to that of experiment. FDTD simulation demonstrated that incident excitation parallel to the interparticle axis induces strong near-field distribution at the interstitials whereas out of plane excitation modifies such confinement depending on the nanometric geometry of the nanoaggregates. Such an observation is indispensable to understand the localized EM field-mediated optical confinement in surfaceenhanced spectroscopy. © (2014) Trans Tech Publications, Switzerland.

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    3
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  • Optical control of plasmonic fields by phasemodulated pulse excitations

    Keisuke Imaeda, Kohei Imura

    Optics Express   21 ( 22 ) 27481 - 27489  2013.11  [Refereed]

     View Summary

    We developed an advanced near-field optical method by combining an ultrafast near-field optical microscope with a prism-based pulse shaping system. We used this apparatus to visualize plasmonic optical fields and to measure the lifetime of plasmons excited on a rough gold film. We also studied the influence of the phase-modulation of the excitation pulse on the spatial distribution of the optical fields. We found that the spatial distribution of the optical fields can be controlled by a negatively chirped pulse. ©2013 Optical Society of America.

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    11
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  • Optical control of plasmonic fields by phase-modulated pulse excitations

    Keisuke Imaeda, Kohei Imura

    OPTICS EXPRESS   21 ( 22 ) 27481 - 27489  2013.11  [Refereed]

     View Summary

    We developed an advanced near-field optical method by combining an ultrafast near-field optical microscope with a prism-based pulse shaping system. We used this apparatus to visualize plasmonic optical fields and to measure the lifetime of plasmons excited on a rough gold film. We also studied the influence of the phase-modulation of the excitation pulse on the spatial distribution of the optical fields. We found that the spatial distribution of the optical fields can be controlled by a negatively chirped pulse. (C) 2013 Optical Society of America

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    11
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  • Time-domain plasmon dynamics measurements by optical nanoscopy

    Hiromi Okamoto, Yoshio Nishiyama, Tetsuya Narushima, Kohei Imura

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   246  2013.09  [Refereed]

  • Visualizing the optical field structures in metal nanostructures

    Hiromi Okamoto, Kohei Imura

    Journal of Physical Chemistry Letters   4 ( 13 ) 2230 - 2241  2013.07  [Refereed]

     View Summary

    Noble metal nanostructures yield confined optical fields on a nanometer scale due to plasmon resonances, and they have potentially novel applications in spectroscopic analysis, photochemical reactions, optical devices, bioimaging, and so forth. To design nanoscale confined optical fields for use in specific applications, visualization of the fields is needed to provide essential information. We adopted near-field optical microscopy to visualize the optical fields in the present study. Examples of the direct visualization of optical fields in metal nanostructures are presented together with the analysis of the unique spectroscopic characteristics based on near-field imaging. For single nanoparticles such as gold nanorods, the plasmon standing wave functions and/or enhanced local fields near the particles were visualized depending on the particle shapes and sizes. In the assembled nanoparticles, the enhanced optical fields at the gap sites between the particles were visualized, thus elucidating the mechanism of surface-enhanced Raman scattering. The characteristic optical fields for various other metal nanostructures are also discussed. © 2013 American Chemical Society.

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  • Strong optical coupling between mutually orthogonal plasmon oscillations in a silver nanosphere-nanowire joined system

    Seongyong Kim, Kohei Imura, Minwoo Lee, Tetsuya Narushima, Hiromi Okamoto, Dae Hong Jeong

    Physical Chemistry Chemical Physics   15 ( 12 ) 4146 - 4153  2013.03  [Refereed]

     View Summary

    A top-to-bottom joined system consisting of a silver nanowire and nanospheres was fabricated by embedding silver nanospheres on a glass or silicon substrate on which 3-aminothiophenol as an analyte molecule was adsorbed, and then placing silver nanowires on the substrate to make gap sites between a nanowire and nanospheres. In the far-field Raman measurements, the sphere under the wire exhibited more than 60 times higher Raman enhancement than isolated spheres. The surface enhanced Raman scattering (SERS) spectra obtained by the 647.1 nm excitation showed highly polarized feature, exhibiting ca. 4 times higher SERS intensity for the electric field parallel to the wire axis than that perpendicular to the wire axis while those by the 514.5 nm excitation showed non-polarized feature against the incident electric field direction. The polarized feature by the 647.1 nm excitation is explained in terms of optical coupling in a vertical direction to the substrate plane, between the silver nanosphere and the longitudinal surface plasmon mode of the nanowire. The longitudinal plasmon of the nanowire functions as an antenna of the incident radiation field in this type of coupled plasmon mode, to yield the confined field. Near-field two-photon excitation imaging measurements as well as numerical calculations of the localized electric field around the system support this idea and indicate that the coupling between the surface plasmon of silver nanospheres and the longitudinal mode of silver nanowires is site-selective. © 2013 the Owner Societies.

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  • Optical Field Imaging of Elongated Rectangular Nanovoids in Gold Thin Film

    Kohei Imura, Kosei Ueno, Hiroaki Misawa, Hiromi Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY C   117 ( 6 ) 2449 - 2454  2013.02  [Refereed]

     View Summary

    We studied optical properties of single elongated rectangular nanovoids opened on a thin gold film by scanning near-field optical microscopy. We found that the luminescence is induced via two-photon absorption of near-infrared pulses when the sample is locally photoexcited inside the void as well as on the film. The luminescence spectrum of the void shows spectral features very similar to those observed for gold nanorods and is attributable to that from gold. On the basis of the near-field two-photon excitation imaging by detecting the luminescence, we visualized the optical fields near the voids. The optical image shows a characteristic spatial feature depending on the dimension of the void. From the dose inspection of the topography and the optical images, we found that excitation probability becomes high at the metal void boundary as well as inside the void. We found an oscillating feature along the long axis of the void. The observed spatial features were qualitatively reproduced by photonic local density-of-states based on electromagnetic calculations, and we conduded that the oscillation observed inside the void is attributed to the electromagnetic modes in the void coupled with the plasmon excitations.

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    5
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  • Spatial distribution of enhanced optical fields in one-dimensional linear arrays of gold nanoparticles studied by scanning near-field optical microscopy

    Toru Shimada, Kohei Imura, Hiromi Okamoto, Masahiro Kitajima

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   15 ( 12 ) 4265 - 4269  2013  [Refereed]

     View Summary

    We visualized the enhanced optical field distributions in one-dimensional linear array structures of gold nanospheres by using scanning near-field optical microscopy. The characteristic field distribution depends on the chain length of the one-dimensional structures. The distribution of optical field is reproduced qualitatively by model calculations based upon finite-difference time-domain (FDTD) method. From the analysis, we have found that the characteristic distribution of the enhanced field arises from interparticle interactions, which cause propagation of the plasmon excitation in the inner part of the linear array, and trapping of it by a localized mode at the edges.

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    16
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  • Sub-20-fs Time-Resolved Measurements in an Apertured Near-Field Optical Microscope Combined with a Pulse-Shaping Technique

    Hui Jun Wu, Yoshio Nishiyama, Tetsuya Narushima, Kohei Imura, Hiromi Okamoto

    APPLIED PHYSICS EXPRESS   5 ( 6 )  2012.06  [Refereed]

     View Summary

    We have constructed an ultrafast near-field optical microscope system with near-field pump/probe pulses with a 17 fs duration at the probe tip. The dispersion effects arising from the optical components, especially from the optical fiber, were removed by a pulse-shaping system that consists of passive and adaptive group-velocity dispersion compensators. With this apparatus, we succeeded in measuring dephasing in a single gold nanostructure with a time constant on the order of 10 fs. (C) 2012 The Japan Society of Applied Physics

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  • Plasmon-induced local photocurrent changes in GaAs photovoltaic cells modified with gold nanospheres: A near-field imaging study

    Yosuke Harada, Kohei Imura, Hiromi Okamoto, Yoshiaki Nishijima, Kosei Ueno, Hiroaki Misawa

    JOURNAL OF APPLIED PHYSICS   110 ( 10 )  2011.11  [Refereed]

     View Summary

    Modification of photovoltaic devices with metallic nanoparticles is expected to be one of the key methods for development of high performance devices as a future energy source. To clarify the mechanism of photocurrent changes induced by surface plasmon resonances of metal nanoparticles, we measured near-field photocurrent excitation images for a GaAs photodiode modified with gold nanospheres (diameter 100 nm) with a spatial resolution higher than 100 nm. The relationship between the photovoltaic efficiency and the plasmons of the gold nanospheres was investigated through the measurements of incident wavelength and polarization dependence of the near-field photocurrent images. Isolated nanospheres deposited on the GaAs active surface caused local photocurrent suppressions at the plasmon resonance wavelengths. In the case of assemblies (dimers and trimers) of the spheres, a remarkable decrease of photocurrent at the gap site between the spheres was observed. From the results, it turned out that the enhanced optical fields created via the plasmons on the metal nanostructures do not improve the photovoltaic efficiency and that forward scattering of photons by the gold nanoparticles is considered to be more important than the enhanced field effect at the particles for the GaAs photovoltaic device studied. (C) 2011 American Institute of Physics. [doi:10.1063/1.3662114]

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    7
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  • Spatial distribution of enhanced optical fields in monolayered assemblies of metal nanoparticles: Effects of interparticle coupling

    Hiromi Okamoto, Kohei Imura, Toru Shimada, Masahiro Kitajima

    JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY   221 ( 2-3 ) 154 - 159  2011.06  [Refereed]

     View Summary

    Near-field two-photon excitation images of assemblies of many gold nanospheres show characteristic feature that enhanced optical fields are confined at the rim parts of the assemblies. In the present report we analyzed the origin of this feature based on finite-difference time-domain (FDTD) approach as well as a simple point dipole model that incorporates the interparticle interaction with the dipole-dipole potential. It has been found that the simple point dipole model is useful for qualitative discussion on the optical field distribution in the metal nanoparticle assemblies. From the analysis, we have found that the interparticle interaction, which causes the propagation of the plasmon excitation in the assemblies, seems to be essential for the localization of the enhanced field at the rim. We propose that regular close-packed assemblies do not yield efficiently enhanced optical fields in visible to near-infrared region, and rather assemblies with large fluctuation are more advantageous to get highly enhanced fields. (C) 2011 Elsevier B.V. All rights reserved.

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    10
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  • Nanoscale Two-Photon Induced Polymerization of Diacetylene Langmuir-Blodgett Film by Near-Field Photoirradiation

    Akira Sakamoto, Kazuhiko Mori, Kohei Imura, Hiromi Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY C   115 ( 14 ) 6190 - 6194  2011.04  [Refereed]

     View Summary

    We have succeeded in nanoscale polymerization of Langmuir-Blodgett (LB) films of cadmium 10,12-pentacosadiynoate (CdPA) by near-field two-photon excitation with femtosecond pulses. The LB films of CdPA were excited locally through an aperture of a near-field optical fiber probe by femtosecond-pulsed near-infrared radiation. The formation of polydiacetylene (PDA) films has been LB film confirmed by two-photon induced and ordinary (linear) luminescence and Raman measurements by using a scanning near-field optical microscope. The polymerization of CdPA to PDA was induced by the femtosecond-pulsed near-infrared radiation but not by continuous wave radiation. This result confirms that the polymerization was not induced by heat arising from the near-field irradiation. The number of photons involved in the polymerization reaction was estimated to be 2 from the dependence of photoluminescence intensities of PDA on the power of incident light for polymerization.

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    5
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  • Anomalous Light Transmission from Plasmonic Capped Nano-apertures

    K. Imura, K. Ueno, H. Misawa, H. Okamoto

    Nano Lett.   11 ( 3 ) 960 - 965  2011.03  [Refereed]

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  • Anomalous light transmission from plasmonic-capped nanoapertures.

    Imura Kohei, Ueno Kosei, Misawa Hiroaki, Okamoto Hiromi

    Nano Letters   11 ( 3 ) 960 - 965  2011.03  [Refereed]

     View Summary

    :We report an anomalous light transmission phenomenon for a nanoaperture on an opaque screen when the aperture is covered with an opaque cap. In conventional optics, light transmission must decrease when the aperture is capped. However, we found that light transmission is enhanced when the nanodisk is in close proximity to the aperture at a wavelength close to the plasmon resonance. This effect even occurs when the disk is larger than the aperture.

    DOI PubMed

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    33
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  • Confined Optical Fields in Nanovoid Chain Structures Directly Visualized by Near-Field Optical Imaging

    Su Il Kim, Kohei Imura, Sehun Kim, Hiromi Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY C   115 ( 5 ) 1548 - 1555  2011.02  [Refereed]

     View Summary

    Linearly aligned nanovoid chain structures on Au thin films were fabricated on glass substrates. Two-photon excitation imaging techniques using an aperture-type near-field scanning optical microscope revealed localized optical field distributions due to the individual structures. Confined optical fields due to the void chains were observed at each interstitial gap between voids with excitation polarization parallel to the chain axis. Electromagnetic field simulations of dimeric voids qualitatively matched the experimental results. Under excitation polarization perpendicular to the chain axis, only weak optical fields were observed. Further detailed characteristics of localized optical fields in these systems, including those in relation to Babinet's principle in optics, were discussed. Our study may open up new possibilities in molecular sensing and photochemistry.

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  • FDTD Simulated Observation of a Gold Nanorod by Scanning Near-Field Optical Microscopy

    K. Sawada, H. Nakamura, T. Maruoka, Y. Tamura, K. Imura

    Plasma and Fusion Research: Regular Articles   5   S2110 - S2110  2010

     View Summary

    The optical properties of a gold nanorod were investigated by Imura et al. [J. Chem. Phys. 122, 154701 (2005)] using an apertured-type scanning near-field optical microscope (SNOM). The observed transmission image showed an oscillating pattern along the long axis of the nanorod. We obtain the image using the finitedifference time-domain (FDTD) method. Our model includes a nanorod on a glass substrate, a SNOM, and current as a light source. We develop a simple method for including the Drude-Lorentz dispersion relation of Vial et al. [Phys. Rev. B 71, 085416 (2005)] for gold in the FDTD. The oscillating pattern is explained by the total current in the nanorod, tip of the SNOM, and light source.

    DOI

  • Properties of photoluminescence from single gold nanorods induced by near-field two-photon excitation

    Kohei Imura, Hiromi Okamoto

    Journal of Physical Chemistry C   113 ( 27 ) 11756 - 11759  2009.07  [Refereed]

     View Summary

    We investigated properties of photoluminescence from single gold nanorods induced by near-field two-photon excitation, using scanning near-field optical microscopy. Photoluminescence spectrum showed two peaks around 550 and 650 nm in wavelengths regardless of the rod dimensions, whereas the intensity ratio of the two spectral components varies from rod to rod. We discussed the observed spectral features of photoluminescence based on electromagnetic calculations and found that the observed spectral features can be explained in terms of local field enhancement in the vicinity of the gold nanorod due to plasmon-mode excitation. © 2009 American Chemical Society.

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  • Near-field optical imaging of enhanced electric fields and plasmon waves in metal nanostructures

    Hiromi Okamoto, Kohei Imura

    PROGRESS IN SURFACE SCIENCE   84 ( 7-8 ) 199 - 229  2009.07  [Refereed]

     View Summary

    In this article, studies on noble metal nanostructures using near-field optical microscopic imaging are reviewed. We show that near-field transmission imaging and near-field two-photon excitation imaging provide valuable methods for investigation of plasmon resonances in metal nanostructures. The eigenfunctions of plasmon modes in metal nanoparticles are directly visualized using these methods. For metal nanowire systems, wavevectors of the longitudinal plasmon modes can be estimated directly from the wave-function images, and the dispersion relations are plotted and analyzed. Using ultrafast transient near-field imaging, we show that the deformation of the plasmon wave function takes place after photoexcitation of a gold nanorod. Such methods of plasmon-wave imaging may provide a unique basic toot for designing plasmon-mode-based nano-optical devices. We also demonstrate that the near-field two-photon excitation probability images reflect localized electric-field enhancements in metal nanostructures. We apply this method to gold nanosphere assemblies and clearly visualize the local enhanced optical fields in the interstitial sites between particles (hot spots). We also show the contribution of hot spots to surface enhanced Raman scattering. The methodology described here may provide valuable basic information about the characteristic enhanced optical fields in metal nanostructures as well as on their applications to new innovative research areas beyond the conventional scope of materials. (C) 2009 Elsevier Ltd. All rights reserved.

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  • Bioimaging with Two-Photon-Induced Luminescence from Triangular Nanoplates and Nanoparticle Aggregates of Gold

    Yuqiang Jiang, Noriko Nishizawa Horimoto, Kohei Imura, Hiromi Okamoto, Ko Matsui, Ryuichi Shigemoto

    ADVANCED MATERIALS   21 ( 22 ) 2309 - +  2009.06  [Refereed]

     View Summary

    Cell imaging with two-photon-induced photoluminescence is demonstrated using gold nanoparticles (either triangular nanoplates or nanosphere aggregates) as imaging agents. On being conjugated to yeast cells, gold nanoplates exhibit visible two-photon excited luminescence that can be detected by two-photon laser scanning microscopy. The cells can be either dried (in the air) or alive (in water).

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  • Two-photon imaging of localized optical fields in the vicinity of silver nanowires using a scanning near-field optical microscope

    Kohei Imura, Young Chae Kim, Seongyong Kim, Dae Hong Jeong, Hiromi Okamoto

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   11 ( 28 ) 5876 - 5881  2009  [Refereed]

     View Summary

    We report a near-field two-photon excitation imaging technique for silver nanostructures to visualize optical fields in the vicinity of nanostructures. We have found that the excitation image of an isolated wire shows an oscillating feature along the long axis of the wire. The period of the oscillation is in good agreement with that of plasmon wavefunctions resonant with the excitation light. The oscillation was thus attributed to the resonant plasmon wavefunction. We also found that bundles of wires exhibit more intense photoluminescence signals than do isolated wires, particularly at junctions between wire ends and the shafts of other wires, which was attributed to the amplified optical fields at the ends of nanowires or interstitial gaps between the wires. We discuss the mechanism of the photoluminescence from silver nanowires. The photoluminescence is most probably attributed to emission from the oxidized surface layer of the silver nanowires, which is enhanced in resonance with plasmons on the wires.

    DOI PubMed

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  • Dye fluorescence enhancement and quenching by gold nanoparticles: Direct near-field microscopic observation of shape dependence

    Noriko Nishizawa Horimoto, Kohei Imura, Hiromi Okamoto

    Chemical Physics Letters   467 ( 1-3 ) 105 - 109  2008.12  [Refereed]

     View Summary

    We investigated the enhancement and quenching of dye fluorescence by single gold nanoparticles using an aperture-type scanning near-field optical microscope to evaluate the shape dependence. Enhancement or reduction of fluorescence was found to be strongly dependent on the shape of the particle. Gold nanoplates showed significant fluorescence enhancement, as did aggregated nanoparticles for the most part. On the other hand, gold nanorods with high aspect ratios showed quenching effects. The results suggest that the electromagnetic near-field in the vicinity of the surface of nanoparticles, not just near the apex or the tip but the whole surface, is important for understanding fluorescence enhancement and quenching. © 2008 Elsevier B.V. All rights reserved.

    DOI

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    51
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  • Near-field Raman imaging and electromagnetic field confinement in the self-assembled monolayer array of gold nanoparticles

    Mohammad Kamal Hossain, Toru Shimada, Masahiro Kitajima, Kohei Imura, Hiromi Okamoto

    LANGMUIR   24 ( 17 ) 9241 - 9244  2008.09  [Refereed]

     View Summary

    Spatial distribution of surface enhanced Raman activity is visualized for two-dimensional (2D) nearly close-packed and well-ordered monolayer array of gold nanoparticles by using scanning near-field optical microscope. The 2D arrays exhibit highly nonuniform enhancement in Raman scattering, i.e., the regions along the edge of the 2D array are preferentially enhanced. We demonstrate that the spatial distribution of the localized electric field is also nonuniform and agrees well with that of the Raman enhancement.

    DOI PubMed

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    40
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  • PHYS 433-Electric-field distribution at interstitial sites in linear nanohole array structures of gold revealed by near-field two-photon excitation

    Su Il Kim, Kohei Imura, Hiromi Okamoto, Sehun Kim

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   236  2008.08  [Refereed]

  • Near-field optical imaging of nanoscale optical fields and plasmon waves

    Hiromi Okamoto, Kohei Imura

    Japanese Journal of Applied Physics   47 ( 7 ) 6055 - 6062  2008.07  [Refereed]

     View Summary

    Near-field optical microscopy enables spectroscopic and imaging measurements with a spatial resolution far beyond the diffraction limit of light. We show in this review that spatial structures of plasmonic wavefunctions and those of enhanced optical fields are visualized by near-field spectroscopic imaging for gold nanoparticles and their assemblies. A simple formulation for the optical observation of wavefunctions of oscillating polarization modes in nanomaterials is given. We will introduce experimental methods for near-field linear transmission and nonlinear two-photon excitation measurements. We will demonstrate that the wavefunctions of surface plasmons resonant with the incident wavelength are visualized by the near-field methods for gold nanorods. In addition, we will also show for aggregated gold nanospheres that an enhanced optical field is localized in the interstitial gaps between the particles by near-field two-photon excitation measurements. © 2008 The Japan Society of Applied Physics.

    DOI

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    16
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  • Development of novel near-field microspectroscopy and imaging of local excitations and wave functions of nanomaterials

    Kohei Imura, Hiromi Okamoto

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   81 ( 6 ) 659 - 675  2008.06  [Refereed]

     View Summary

    We have developed novel methods of near-field microspectroscopy by combining near-field optical microscopy with linear and non-linear optical techniques. The developed near-field microscope achieves high spatial resolution and high time resolution, and is applied to studies of local excitations and wave functions of single noble metal nanoparticles. We demonstrate that the plasmon wave functions and the optical fields in the vicinity of nanoparticles are visualized by the near-field methods. Based on these results, we clearly show that localized electromagnetic field enhancement in the vicinity of nanoparticles is one of the most important factors in surface-enhanced spectroscopies. We also extended the methods to ultrafast optical measurements, and show space-resolved ultrafast transient response of single gold nanorods. The characteristic spatio-temporal features observed in the nanorods are revealed to be arising from the changes of the plasmon-mode wave functions upon elevation of photo-induced electronic temperature of the nanorod.

    DOI

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    34
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  • Near-field study on correlation of localized electric field and nanostructures in monolayer assembly of gold nanoparticles

    Toru Shimada, Kohei Imura, Mohammad Kamal Hossain, Hiromi Okamoto, Masahiro Kitajima

    JOURNAL OF PHYSICAL CHEMISTRY C   112 ( 11 ) 4033 - 4035  2008.03  [Refereed]

     View Summary

    We. clarified the relationship between near-field optical properties and the local structure in monolayer assembly of gold nanoparticles by using scanning near-field optical microscopy (SNOM) and scanning electron microscopy (SEM). The success of superposition of the SNOM image with the SEM image allows us to find that the intense electromagnetic field is localized at the rim part, especially the interstitial site of the dimerlike structure.

    DOI

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    44
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  • Raman and near-field spectroscopic study on localized surface plasmon excitation from the 2D nanostructure of gold nanoparticles

    M. K. Hossain, T. Shimada, M. Kitajima, K. Imura, H. Okamoto

    JOURNAL OF MICROSCOPY-OXFORD   229 ( 2 ) 327 - 330  2008.02

     View Summary

    We have studied electromagnetic field on the surface of two-dimensional nanostructure of gold nanoparticles through two-photon-induced photoluminescence images by using scanning near-field optical microscope and far-field surface-enhanced Raman scattering measurements. The near-field two-photon-induced photoluminescence image shows that strong inhomogeneous enhancement in two-photon-induced photoluminescence occurs over the two-dimensional nanostructure, representing localized surface plasmon excitations. The results suggest that the local structure of the two-dimensional nanostructure influences the distribution of localized surface plasmon excitation.

    DOI

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    23
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  • Ultrafast photoinduced changes of eigenfunctions of localized plasmon modes in gold nanorods

    Kohei Imura, Hiromi Okamoto

    Physical Review B - Condensed Matter and Materials Physics   77 ( 4 ) 41401  2008.01  [Refereed]

     View Summary

    Ultrafast transient responses in single gold nanorods are visualized in real space by femtosecond pump-probe measurements using a near-field optical microscope. The observed transient images show characteristic features, and the features are strongly dependent on the size of the rod. It is revealed that the features arise from changes in the plasmon-mode wave function upon elevation of the electronic temperature of the nanorod induced by photoexcitation. © 2008 The American Physical Society.

    DOI

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    19
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  • Near-Field Studies of Plasmon Wavefunctions and Optical Fields in Gold Nanoparticles

    Imura Kohei

    Mol. Sci.   1 ( 1 ) A0006 (J-STAGE)  2007

     View Summary

    We studied single gold nanoparticles and aggregates by linear and non-linear optical methods combined with near-field optical microscopy. Near-field images of gold nanorods obtained show peculiar spatial patterns, and are strongly dependent on wavelength observed. The images are attributed to spatial characteristics of plasmon modes (wavefunctions), and are consistent with theoretical simulations. We also studied spatial distributions of optical fields by using near-field two-photon-induced photoluminescence and Raman imaging techniques. We revealed that optical fields are highly confined at interstitial sites in dimers of spherical gold nanospheres, and such an amplified electromagnetic field is one of the most important origins in single molecular sensitivity surface enhanced Raman scattering.

    DOI CiNii J-GLOBAL

  • Imaging of optical field distributions and plasmon wavefunctions in metal nanoparticles - art. no. 66420A

    Hiromi Okamoto, Kohei Imura

    PLASMONICS: NANOIMAGING, NANOFABRICATION, AND THEIR APPLICATIONS III   6642   A6420 - A6420  2007  [Refereed]

     View Summary

    We report in this paper the near-field microscopic studies on localized plasmon resonances in gold nanoparticles and their assemblies (nanorods, triangular nanoplates, and assembled nanospheres). We have utilized near-field measurements of linear transmission/scattering, as well as nonlinear two-photon excitation, to enable spectroscopic imaging of local electric field or local density of electromagnetic states. We show that the wavefunction of the plasmon excitation in the nanoparticle is visualized by the near-field methods. For single nanorod, many plasmon resonances were observed in the near-field transmission spectrum. At each resonant peak wavelength, the near-field image of the nanorod gave a characteristic spatially oscillating feature along the long axis of the nanorod. The feature is attributable to the square modulus of the resonant plasmon-mode wavefunction. In the assembled nanoparticles, strong electric-field enhancement localized in the interstitial sites ("hot spot"), which was theoretically predicted previously, was clearly imaged by the near-field two-photon excitation method. Major contribution of the hot spots to surface enhanced Raman scattering is also shown for the samples weakly doped with Raman-active dye molecules, by the near-field excited Raman spectra and images.

    DOI

    Scopus

    1
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  • Ultrafast near-field microscopy of single gold nanoparticles

    K. Imura, H. Okamoto

    ULTRAFAST PHENOMENA IN SEMICONDUCTORS AND NANOSTRUCTURE MATERIALS XI AND SEMICONDUCTOR PHOTODETECTORS IV   6471   647103  2007

     View Summary

    We investigated near-field optical properties and images of single gold nanorods by using a near-field optical microscope. Observed transmission spectra show distinct transverse and longitudinal surface plasmon resonances. Transmission images observed near the surface plasmon resonances agree qualitatively with calculated maps of optical local density-of-states, and are assignable to plasmon wavefunctions. Ultrafast temporal responses in the single gold nanoparticles were observed by combining a near-field microscope with time-resolved techniques. Observed transient transmission images of the single nanorods show characteristic optical features, and are in good agreement with a calculated map of variation of local density of states arising from the elevation of electronic temperature in the nanorod induced by photoexcitation.

    DOI

    Scopus

  • Visualization of localized intense optical fields in single gold-nanoparticle assemblies and ultrasensitive Raman active sites

    Kohei Imura, Hiromi Okamoto, Mohammad K. Hossain, Masahiro Kitajima

    NANO LETTERS   6 ( 10 ) 2173 - 2176  2006.10  [Refereed]

     View Summary

    We demonstrate visualization of localized intense electromagnetic fields in real space in well-tailored dimeric and trimeric gold nanospheres by using near-field optical techniques. With two-photon induced luminescence and Raman measurements, we show that the electric field is confined at an interstitial site in the aggregate. We also demonstrate optical switching operations for the electric-field localized sites in the trimer structure.

    DOI PubMed

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    224
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  • Reciprocity in scanning near-field optical microscopy: illumination and collection modes of transmission measurements

    K Imura, H Okamoto

    OPTICS LETTERS   31 ( 10 ) 1474 - 1476  2006.05  [Refereed]

     View Summary

    We experimentally investigated the reciprocity of scanning near-field optical microscopy between illumination and collection modes. Near-field transmission images of single gold spheres and nanorods observed by the two modes are found to be equivalent to each other in the region from visible to near infrared. This result shows that reciprocity holds for the near-field scattering problems. We found that the conventional optical selection rule for far-field excitations does not apply not only under illumination mode but also with collection-mode arrangements. The possible origin of this observation might be the near-field probe. (c) 2006 Optical Society of America.

    DOI PubMed

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    29
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  • Near-field imaging of optical field and plasmon wavefunctions in metal nanoparticles

    Hiromi Okamoto, Kohei Imura

    JOURNAL OF MATERIALS CHEMISTRY   16 ( 40 ) 3920 - 3928  2006  [Refereed]

     View Summary

    Scanning near- field optical microscopes enable optical measurements and observations with a spatial resolution far beyond the diffraction limit of light. This allows us to spatially resolve the positions in nanoparticles and at the same time to investigate spectroscopic characteristics point by point. In this feature article, we focus on near- field microscopic studies on surface plasmons in anisotropic gold nanoparticles and aggregates ( nanorods, triangular nanoplates, and aggregated nanospheres). We have utilized linear transmission/ scattering as well as nonlinear two- photon excitation measurements in the near field, to observe the local electric field or electromagnetic local density of states. We show that the wavefunction of the plasmon excitation in the nanoparticle resonant with the incident radiation field is visualized by the near- field methods. In the aggregated nanoparticles, strong electric- field enhancement localized in the interstitial sites, which was theoretically predicted previously, is clearly imaged, and its major contribution to surface enhanced Raman scattering is also shown by the near- field images.

    DOI

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    57
    Citation
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  • Photoluminescence from gold nanoplates induced by near-field two-photon absorption

    K Imura, T Nagahara, H Okamoto

    APPLIED PHYSICS LETTERS   88 ( 2 ) 023104 -1 - 023104 -3  2006.01

     View Summary

    We have investigated two-photon-induced photoluminescence (PL) properties of single gold nanoplates by using an apertured scanning near-field optical microscope. The nanoplates show PL much stronger than nanorods. The near-field PL images show characteristic spatial features, which depend on the incident polarization. These PL images are in good agreement with the calculated spatial distribution of the electric fields adjacent to the particles at the excitation wavelength. We attribute the observed images to spatial characteristics of plasmon modes.

    DOI

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    72
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  • Near-field imaging of surface-enhanced Raman active sites in aggregated gold nanoparticles

    K Imura, H Okamoto, MK Hossain, M Kitajima

    CHEMISTRY LETTERS   35 ( 1 ) 78 - 79  2006.01

     View Summary

    We observed near-field images of aggregates of gold nanospheres, by detecting TPI-PL from gold and Raman scattering from Rhodamine 6G adsorbed oil the nanoparticles. The results were analyzed in relation to the localized Raman active site (hot Spot) of surface-enhanced Raman scattering,.

    DOI

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    40
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  • Morphological and spectroscopic properties of thin films of self-assembling amphiphilic porphyrins on a hydrophilic surface as revealed by scanning near-field optical microscopy

    T Nagahara, K Imura, H Okamoto, A Oguro, H Imahori

    JOURNAL OF PHYSICAL CHEMISTRY B   109 ( 42 ) 19839 - 19844  2005.10  [Refereed]

     View Summary

    We fabricated porphyrin thin films on mica surfaces from acidic aqueous solutions of the preorganized H-aggregates of amphiphilic porphyrins by the simple spin-coating method. The morphological and spectroscopic properties of the film were investigated by scanning near-field optical microscopy. The results obtained in this study demonstrate that the preorganized structure in solution can be transferred as a thin film with a thickness of the monolayer level without losing their substantial structure and photophysical properties.

    DOI PubMed

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    11
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  • Imaging and dispersion relations of surface plasmon modes in silver nanorods by near-field spectroscopy

    JK Lim, K Imura, T Nagahara, SK Kim, H Okamoto

    CHEMICAL PHYSICS LETTERS   412 ( 1-3 ) 41 - 45  2005.08

     View Summary

    Surface plasmons of silver nanorods were investigated by using scanning near-field optical microscopy. Near-field transmission images showed spatially oscillatory patterns in nanorods. The oscillatory features of images are attributable to plasmon-mode wave-functions. From the near-field images and spectra, dispersion relations of surface plasmon modes for various silver nanorods are obtained. It is found that dispersion relation of a nanorod is dependent on its diameter. The spectral features obtained are compared with those for gold nanorods. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

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    44
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  • Near-field two-photon-induced photoluminescence from single gold nanorods and imaging of plasmon modes

    K Imura, T Nagahara, H Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY B   109 ( 27 ) 13214 - 13220  2005.07  [Refereed]

     View Summary

    We investigated the two-photon-induced photoluminescence properties of single gold nanorods by scanning near-field spectroscopy. The process was found to be initiated by a sequential one-photon absorption for creating a pair of an electron and a hole in the sp and d bands. Photoluminescence is then radiated when the electron near the Fermi surface recombines with the hole near the X and L symmetry points. The polarization characteristics of emitted photons from the X and L regions were found to be different. These characteristics can be understood by the crystalline structure and the band structure of the gold nanorod. We found characteristic spatial oscillatory features along the long axis of the nanorods in photoluminescence excitation images. The images were well reproduced by density-of-states maps of the nanorods calculated with Green's dyadic method and were attributed to the spatial characteristics of the wave functions of the plasmon modes inside the nanorods.

    DOI PubMed

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    325
    Citation
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  • Near-field optical imaging of plasmon modes in gold nanorods

    Kohei Imura, Tetsuhiko Nagahara, Hiromi Okamoto

    Journal of Chemical Physics   122 ( 15 ) 154701  2005.04  [Refereed]

     View Summary

    We have investigated optical properties of single gold nanorods by using an apertured-type scanning near-field optical microscope. Near-field transmission spectrum of single gold nanorod shows several longitudinal surface plasmon resonances. Transmission images observed at these resonance wavelengths show oscillating pattern along the long axis of the nanorod. The number of oscillation increases with decrement of observing wavelength. These spatial characteristics were well reproduced by calculated local density-of-states maps and were attributed to spatial characteristics of plasmon modes inside the nanorods. Dispersion relation for plasmons in gold nanorods was obtained by plotting the resonance frequencies of the plasmon modes versus the wave vectors obtained from the transmission images. © 2005 American Institute of Physics.

    DOI PubMed

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    144
    Citation
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  • Pump-probe near-field optical microscopy of molecular aggregates using supercontinuum

    T Nagahara, K Imura, H Okamoto

    ULTRAFAST PHENOMENA XIV   79   434 - 436  2005

     View Summary

    A novel apparatus for femtosecond pump-probe near-field optical microscopy is described. Probe pulses in visible to near-infrared regions are generated by focusing laser pulses in microstructure fiber. Excited-state dynamics of porphyrin J-aggregates are presented.

  • Ultrafast near-field microscope imaging of electron and phonon relaxation in single gold nanoparticle

    K Imura, T Nagahara, H Okamoto

    ULTRAFAST PHENOMENA XIV   79   655 - 657  2005

     View Summary

    We investigated near-field optical properties of single gold nanorods. Transmission images observed near the surface plasmon resonances agree with calculated local density of states. Ultrafast temporal responses of single rods have been imaged by combining near-field microscope with time-resolved technique. It has been found that dynamic behavior in the center of the rod is different from that in the both ends.

  • Ultrafast near-field microscope imaging of electron and phonon relaxation in single gold nanoparticle

    K Imura, T Nagahara, H Okamoto

    ULTRAFAST PHENOMENA XIV   79   655 - 657  2005

     View Summary

    We investigated near-field optical properties of single gold nanorods. Transmission images observed near the surface plasmon resonances agree with calculated local density of states. Ultrafast temporal responses of single rods have been imaged by combining near-field microscope with time-resolved technique. It has been found that dynamic behavior in the center of the rod is different from that in the both ends.

  • Pump-probe near-field optical microscopy of molecular aggregates using supercontinuum

    T Nagahara, K Imura, H Okamoto

    ULTRAFAST PHENOMENA XIV   79   434 - 436  2005

     View Summary

    A novel apparatus for femtosecond pump-probe near-field optical microscopy is described. Probe pulses in visible to near-infrared regions are generated by focusing laser pulses in microstructure fiber. Excited-state dynamics of porphyrin J-aggregates are presented.

  • Characteristic near-field spectra of single gold nanoparticles

    K Imura, T Nagahara, H Okamoto

    CHEMICAL PHYSICS LETTERS   400 ( 4-6 ) 500 - 505  2004.12

     View Summary

    We investigate the interaction between evanescent wave and a single gold nanoparticle in near-field by utilizing an aperture-probe scanning near-field optical microscope. A characteristic spectral feature, consisting of transmission enhancement and absorptive parts, is found. Observed spectra are successfully simulated both by a model calculation based on extended Mie scattering theory of the near- and far-field scatterings as well as by a Green's dyadic method. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

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    43
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  • Near-field spectroscopy of water-soluble and water-insoluble porphyrin J-aggregates

    Tetsuhiko Nagahara, Kohei Imura, Kohei Imura, Hiromi Okamoto, Hiromi Okamoto

    Scanning   26 ( 5 SUPPL. )  2004.11

     View Summary

    Mesoscopic properties of J-aggregates of water-soluble [tetrakis(4- sulfonatophenyl)porphyrin] and water-insoluble [tetrakis(4-methoxyphenyl) porphyrin and tetraphenylporphyrin] tetraphenylporphyrin derivatives in thin films have been investigated by scanning near-field optical microscopy. From surface topography, the sample films were found to be composed of planar J-aggregate microcrystallines. The transmittance spectra of the water-insoluble samples are site specific, while those of the water-soluble samples are not. This observation might reflect the spatial inhomogeneity of the thin films in mesoscopic scales and is related to the broad J-bands of water-insoluble samples. Excited state lifetimes, obtained from time-resolved, pump-probe measurements in small domains, were in the 30-70 ps range for 4-methoxy substituted and in the 40-100 ps range for unsubstituted tetraphenylporphyrin, which are of the same order as the reported far-field results for 4-sulfonated compound in water.

  • Time-resolved scanning near-field optical microscopy with supercontinuum light pulses generated in microstructure fiber

    T Nagahara, K Imura, H Okamoto

    REVIEW OF SCIENTIFIC INSTRUMENTS   75 ( 11 ) 4528 - 4533  2004.11

     View Summary

    A novel apparatus for time-resolved near-field optical microscopy is described. The apparatus consists of a mode-locked Ti:sapphire laser, a microstructure fiber, and a scanning near-field optical microscope equipped with an apertured optical fiber probe. The probe pulses in visible to near-infrared regions are generated by focusing laser pulses in the microstructure fiber. The broadband continuum can be used as a wavelength-tunable light source for fluorescence excitation as well as for probing absorption of excited states at arbitrary wavelengths by applying pump-probe scheme, in high spatial-resolution (similar to100 nm) predominantly determined by the aperture size of the tip. Time resolution obtained with 740-830 nm probe pulses was in 1-2 ps range, while that with 570 nm pulses was 5 ps without precompensation of the group delay dispersion for the probe pulses. Results on the excited-state dynamics of molecular aggregates are presented. (C) 2004 American Institute of Physics.

    DOI

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    30
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  • Plasmon mode imaging of single gold nanorods

    K Imura, T Nagahara, H Okamoto

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   126 ( 40 ) 12730 - 12731  2004.10

    DOI

  • Plasmon mode imaging of single gold nanorods

    K Imura, T Nagahara, H Okamoto

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   126 ( 40 ) 12730 - 12731  2004.10

    DOI

  • Imaging of surface plasmon and ultrafast dynamics in gold nanorods by near-field microscopy

    K Imura, T Nagahara, H Okamoto

    JOURNAL OF PHYSICAL CHEMISTRY B   108 ( 42 ) 16344 - 16347  2004.10

     View Summary

    We investigated the near-field optical properties of single gold nanorods. Transmission images observed near the surface plasmon resonances agree qualitatively with the calculated maps of the optical local density of states and are reflected by spatial characteristics of plasmon wave functions. Ultrafast temporal responses have been observed by combining near-field microscopy with a time-resolved technique. It has been found that the behavior of the collective motion of electrons in the center of the rod is different from that in both ends.

    DOI

    Scopus

    98
    Citation
    (Scopus)
  • Near-field spectroscopy of water-soluble and water-insoluble porphyrin J-aggregates

    T Nagahara, K Imura, H Okamoto

    SCANNING   26 ( 5 ) I10 - I15  2004.09  [Refereed]

     View Summary

    Mesoscopic properties of J-aggregates of watersoluble [tetrakis(4-sulfonatophenyl)porphyrin] and water-insoluble [tetrakis(4-methoxyphenyl)porphyrin and tetraphenylporphyrin] tetraphenylporphyrin derivatives in thin films have been investigated by scanning near-field optical microscopy. From surface topography, the sample films were found to be composed of planar J-aggregate microcrystallines. The transmittance spectra of the water-insoluble samples are site specific, while those of the water-soluble samples are not. This observation might reflect the spatial inhomogeneity of the thin films in mesoscopic scales and is related to the broad J-bands of water-insoluble samples. Excited state lifetimes, obtained from time-resolved, pump-probe measurements in small domains, were in the 30-70 ps range for 4-methoxy substituted and in the 40-100 ps range for unsubstituted tetraphenylporphyrin, which are of the same order as the reported far-field results for 4-sulfonated compound in water.

    PubMed

  • Near-field spectroscopy of water-soluble and water-insoluble porphyrin J-aggregates

    T Nagahara, K Imura, H Okamoto

    SCANNING   26 ( 5 ) I10 - I15  2004.09

     View Summary

    Mesoscopic properties of J-aggregates of watersoluble [tetrakis(4-sulfonatophenyl)porphyrin] and water-insoluble [tetrakis(4-methoxyphenyl)porphyrin and tetraphenylporphyrin] tetraphenylporphyrin derivatives in thin films have been investigated by scanning near-field optical microscopy. From surface topography, the sample films were found to be composed of planar J-aggregate microcrystallines. The transmittance spectra of the water-insoluble samples are site specific, while those of the water-soluble samples are not. This observation might reflect the spatial inhomogeneity of the thin films in mesoscopic scales and is related to the broad J-bands of water-insoluble samples. Excited state lifetimes, obtained from time-resolved, pump-probe measurements in small domains, were in the 30-70 ps range for 4-methoxy substituted and in the 40-100 ps range for unsubstituted tetraphenylporphyrin, which are of the same order as the reported far-field results for 4-sulfonated compound in water.

  • Structures and its dipole moments of half-sandwich type metal-benzene (1 : 1) complexes determined by 2-m long electrostatic hexapole

    K Imura, H Ohoyama, T Kasai

    CHEMICAL PHYSICS   301 ( 2-3 ) 183 - 187  2004.06

     View Summary

    The transition metal-benzene (1:1) complexes are synthesized by laser evaporation method followed by the size and structure selection with 2-m long electrostatic hexapole field. Electric dipole moments of half-sandwich type binary complexes for a series of the transition metals, i.e. Ti, V, Co, and Ni, with benzene molecule were determined by measuring the focusing curves, namely the dependence of the focused beam intensity upon the hexapole field strength. It is found that the dipole moments of Ti-C6H6 and V-C6H6 are larger than the ones of Co-C6H6 and Ni-C6H6. Such large dipole moments of Ti-C6H6 and V-C6H6 can be ascribed to the strong orbital interaction due to charge transfer between the metal atom and benzene molecule. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

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    20
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  • Spectral inhomogeneities and spatially resolved dynamics in porphyrin J-aggregate studied in the near-field

    T Nagahara, K Imura, H Okamoto

    CHEMICAL PHYSICS LETTERS   381 ( 3-4 ) 368 - 375  2003.11

     View Summary

    Mesoscopic properties of water-insoluble tetrakis(4-methoxyphenyl)porphyrin J-aggregate in thin film have been investigated by time-resolved scanning near-field optical microscopy. The film was found to be composed of planar microcrystallines with lengths of a few micrometers, widths of similar to100 nm, and similar to20 nm heights. The transmittance spectra are site-specific. This observation might reflect inhomogeneity of the sample, and is related to the broad J-bands compared to those of tetrakis(4-sulfonatophenyl)porphyrin. Excited-state lifetimes, obtained from pump-probe measurements in small domains, were ranging from 10 to 50 ps that are of the same order with the far-field results. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

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    35
    Citation
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  • Metal-ligand interaction of Ti-C6H6 complex size-selected by a 2-m long electrostatic hexapole field

    K Imura, H Ohoyama, T Kasai

    CHEMICAL PHYSICS LETTERS   369 ( 1-2 ) 55 - 59  2003.02

     View Summary

    Supersonic beam of size-selected Ti-C6H6 metal-ligand binary complex was generated by a laser evaporation method followed by the size selection with 2-m long electrostatic hexapole field. The dependence of the beam intensity upon the hexapole field strength was measured in order to determine permanent dipole moment and complex symmetry. We find that the structure of Ti-C6H6 complex has nearly C-6v symmetry and its electric dipole moment is 2.4 +/- 0.3 D. The calculation with use of density functional theory substantiated its optimized structure as C-6v symmetric in accordance with the experimental result. The calculation also suggests that charge transfer interaction between Ti Atom and C6H6 plays a central role to stabilize the complex. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

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    18
    Citation
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  • Two-dimensional penning ionization electron spectroscopy of HCl with He*(2(3)S) atom

    K Imura, N Kishimoto, K Ohno

    JOURNAL OF PHYSICAL CHEMISTRY A   106 ( 15 ) 3759 - 3765  2002.04

     View Summary

    Penning ionization of HCl upon collision with metastable He*(2(3)S) atoms was studied by two-dimensional (collision-energy/electron energy resolved) Penning ionization electron spectroscopy and by classical trajectory calculations. Collision energy resolved studies enable us to obtain important information about stereo dynamical aspects on this reaction; sideways approaches of the He* atoms on H-Cl molecular axis play a dominant role in the ionization event for producing HCl+(X (2)Pi(i), v' = 0, 1), and glancing collision is one of the dominant trajectories of the He* atoms to produce HCl+(A, (2)Sigma(+)). It was also found that the formation of vibrationally excited HCl+(X (2)Pi(i), v' &gt; 1) through the unidentified HCl** Rydberg state was influenced by a strong attractive interaction, whereas the formation of the HCl** Rydberg state, dissociating to H(1s) and autoionizing Cl**(D-1(2) nl) atoms, was found to be affected by a repulsive interaction around the Cl end of the HCl molecule.

    DOI

    Scopus

    10
    Citation
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  • Reactivity and anisotropic interaction of 1,3,5-C6H3F3 and C6F6 with He*(2(3)S) atoms: Comparison with mono- and di-fluorobenzenes

    K Imura, N Kishimoto, K Ohno

    JOURNAL OF PHYSICAL CHEMISTRY A   105 ( 48 ) 10781 - 10790  2001.12

     View Summary

    Two-dimensional (collision-energy/electron-energy-resolved) Penning ionization electron spectroscopy (2D-PIES) have been applied to the reaction of 1,3,5-C6H3F3 and C6F6 with metastable He*(2(3)S) atoms. Collision energy dependence of the partial ionization cross sections (CEDPICS), which reflects interaction potential energy between the molecule and the He*(23S) atom, indicated anisotropic interaction around the molecules. Assignments of the Penning ionization electron spectra and He I ultraviolet photoelectron spectra have been made by the characteristics of the 2D-PIES. Furthermore, substituent effects on the reactivity of molecular orbitals and also on the interactions around the molecules for various fluorobenzenes were investigated. It was found that the reactivity of the molecular orbitals were closely related to the amount of F atomic orbital components in the orbital. Furthermore, an elucidation of the substituent effect on the interaction behaviors around the molecules gives us important insights on the dynamics of the colliding particles.

    DOI

    Scopus

    10
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    (Scopus)
  • Two-dimensional Penning ionization electron spectroscopy of dichlorobenzenes: Orbital reactivity and anisotropic interaction of dichlorobenzenes with He*(2(3)S)

    K Imura, N Kishimoto, K Ohno

    JOURNAL OF PHYSICAL CHEMISTRY A   105 ( 40 ) 9111 - 9122  2001.10

     View Summary

    Ionization of dichlorobenzenes with metastable He*(2(3)S) atoms was studied by two-dimensional (collision-energy/electron-energy-resolved) Penning ionization electron spectroscopy. Collision energy dependence of the partial ionization cross sections (CEDPICS), which reflects the interaction potential energy between the molecule and He*(2(3)S), showed anisotropic interaction around the molecules. The pi and n (nonbonding) orbitals regions of the molecules showed attractive interactions. It was also found that the magnitude of lattractive interaction around the Cl atom lone pair region perpendicular to the phenyl ring was o- &gt; p- &gt; M-C6H4Cl2, Negative slopes of CEDPICS for sigma type bands indicate an attractive effect for ionization reaction by a substitution of the Cl atom.

    DOI

    Scopus

    10
    Citation
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  • Anisotropic interaction of halogen atom in C2H5X (X = Cl, F) with He*(2(3)S) as probed by two-dimensional Penning ionization electron spectroscopy

    K Imura, N Kishimoto, K Ohno

    JOURNAL OF PHYSICAL CHEMISTRY A   105 ( 26 ) 6378 - 6385  2001.07

     View Summary

    Penning ionization of C2H5X (X = Cl, F) upon collision with metastable He*(2(3)S) atoms was studied by two-dimensional (collision-energy/electron energy resolved) Penning ionization electron spectroscopy. Partial ionization cross sections are found to be larger for ionization from orbitals having n(x) characters. Collision energy dependence of the partial cross sections, which reflects interaction potential energy between the molecule and He(2(3)S), indicates anisotropic interaction potentials around the molecule. As elucidate with the aid of calculated energy surfaces for the chemically related systems Li-C2H5X (X = Cl, F), a different trend was found in the interaction around C-X axis: for the former the attractive interaction was dominated around the perpendicular directions to the C-CI bond axis, while for the C-F bond the attractive interaction was localized around the collinear axis.

    DOI

    Scopus

    12
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  • Collision-energy-resolved penning ionization electron spectroscopy of difluorobenzenes: Anisotropic interaction of difluorobenzenes with He*(2(3)S) and assignments of ionic states

    K Imura, N Kishimoto, K Ohno

    JOURNAL OF PHYSICAL CHEMISTRY A   105 ( 25 ) 6073 - 6083  2001.06

     View Summary

    Penning ionization of difluorobenzenes upon collision with metastable He*(2(3)S) atoms was studied by two-dimensional (collision-energy/electron-energy-resolved) Penning ionization electron spectroscopy. Collision energy dependence of the partial ionization cross sections (CEDPICS), which reflects interaction potential energy between the molecule and He*(23S), showed anisotropic interaction around the molecules. Assignments of the Penning ionization electron spectra and He I ultraviolet photoelectron spectra were discussed on the basis of different behavior of CEDPICS and calculated ionization potentials by the outer valence Green's function (OVGF) method. Furthermore, the ordering of the reactivity of the n(//) and sigma (CF) orbitals and the magnitude of attractive interaction around the F atoms with the metastable atom was found to be o- &gt; m- similar to p-C5H4F2 It indicates that the wider potential well brings the larger attractive effect for Penning ionization reaction.

    DOI

    Scopus

    9
    Citation
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  • Two-dimensional penning ionization electron spectroscopy of monohalogenobenzenes by He*(2(3)S): C6H5X (X = F, Cl, Br, I)

    K Imura, N Kishimoto, K Ohno

    JOURNAL OF PHYSICAL CHEMISTRY A   105 ( 17 ) 4189 - 4199  2001.05

     View Summary

    Penning ionization of C6H5X (X = F, Cl, Pr, I) upon collision with metastable He*(2(3)S) atoms was studied by two-dimensional (collision-energy/electron-energy-resolved Penning ionization electron spectroscopy. Partial ionization cross sections are found to be larger for ionization from orbitals having n and Jr characters. Interaction potentials between the target molecule and the He* atom were found to be highly anisotropic. Attractive interaction was dominated around the collinear access of He*(2(3)S) to C-F axis in C6H5F On the other hand, attractive interaction was localized around the out-of-plane perpendicular approach of He* atom to C-X bond (X = Cl, Pr, I). Attractive interaction for these compounds increases on going from C6H5Cl to C6H5I. Furthermore, the electronic factor due to the size of the halogen p orbitals and the conjugation between the benzene ring and the halogen atoms and also the steric factor due to the shielding effect were found to be important.

    DOI

    Scopus

    27
    Citation
    (Scopus)
  • Evidence for the HCl+(A) formation in the reaction of Ne(3P) with the size-selected HCl dimer using an electrostatic hexapole field

    Kohei Imura, Hiroshi Ohoyama, Toshio Kasai

    Chemistry Letters   ( 11 ) 1136 - 1137  2001

     View Summary

    Penning ionization of Ne(3P) metastable atom with size-selected HCl dimer was studied by using an electrostatic hexapole field and chemiluminescence detection. We found that the HCl dimer can also produce HCl+(A) ions in the reaction with Ne(3P) just like its corresponding monomer reaction. The internal energy distribution of HCl+(A) in the dimer reaction is cooler than that in the monomer reaction, reflecting the third-body effect due to the other HCl in the dimer.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Non-destructive selection of geometrical isomers of the Al(C6H6) cluster by a 2 m electrostatic hexapole field

    K Imura, T Kawashima, H Ohoyama, T Kasai, A Nakajima, K Kaya

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   3 ( 17 ) 3593 - 3597  2001

     View Summary

    A supersonic cluster beam containing isomers of Al(C6H6) complexes was generated by laser evaporation, and non-destructively selected using a 2 m long electrostatic hexapole. The focusing curve shows clear evidence that there are two kinds of Al(C6H6) isomers which are slightly different from each other in geometry; one is an asymmetric 1,2-complex and the other nearly C-6v symmetric 1,4-complex. The electric dipole moments of the two isomers are found to be 1.5 +/- 0.1 and 1.4 +/- 0.1 D, respectively. We carried out computation using density functional theory in order to estimate their structures. We found that the 1,2-complex is more stable than the 1,4-complex. The present work confirms that the electrostatic hexapole technique is useful for non-destructive selection of geometrical isomers in a beam.

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • Direct determination of the permanent dipole moments and structures of Al-CH3CN and Al-NH3 by using a 2-m electrostatic hexapole field

    K. Imura, T. Kawashima, H. Ohoyama, T. Kasai

    Journal of the American Chemical Society   123 ( 26 ) 6367 - 6371  2001

     View Summary

    The supersonic beams of the (1-1) metal-ligand complexes of Al-CH3CN and Al-NH3 were produced by a laser evaporation method. Nondestructive structure selection of the complexes and the dipole moment determination were performed by using a 2-m electrostatic hexapole field. The experimentally determined permanent dipole moments are 1.2 ± 0.1 D for Al-CH3CN and 2.7 ± 0.2 D for Al-NH3. We find that the dipole moment of Al-NH3 becomes larger than that of neat NH3, while the formation of the Al-CH3CN complex produces a smaller dipole moment than that of neat CH3CN on the other hand. We performed the ab initio calculations to draw out plausible complex structures and to clarify the bonding character after formation of the complex, and we made comparisons with the computational results done by several groups. The Mulliken population analysis suggests the Al→CH3CN charge flow, but on the other hand the Natural population analysis indicates very little charge flow. For the Al-NH3 complex, the polarization effect of NH3 and the N→Al σ donation would enhance the dipole moment strength. However, there still remains a controversial disagreement between the theoretical predictions and the experimental results. Further experimental determination using the hexapole method for various metal-ligand complexes and clusters could reveal the basic nature of interaction in the complex systems in general, and this method would complement theoretical calculations.

    DOI PubMed

    Scopus

    21
    Citation
    (Scopus)
  • Tunneling motion in (HCl)(2) hydrogen-bonded dimer probed by electrostatic hexapole and Doppler-selected TOF measurement for the internal energy distribution of [ClHCl]

    K Imura, H Ohoyama, R Naaman, DC Che, M Hashinokuchi, T Kasai

    JOURNAL OF MOLECULAR STRUCTURE   552   137 - 145  2000.09

     View Summary

    The tunneling motion in (HCl)(2) hydrogen bonded dimer and its deuterate was probed by a 2 m long electrostatic hexapole field. The focusing curves of the dimers confirmed the existence of homo and heterodimers in the cluster beam. The homodimer, either (HCl)-Cl-35-(HCl)-Cl-35 Or (HCl)-Cl-37-(HCl)-Cl-37, undergoes a fast tunneling motion for the two hydrogen atoms in the dimer. The heterodimer, namely (HCl)-Cl-35-(HCl)-Cl-37, On the other hand, does not show such fast tunneling motion in the time scale of the experiment. The electric dipole moments for both (DCl)(2) isotopomers were determined to be 1.5 +/- 0.2 D, which is the same value for (HCl)(2). The observed ratio of homo to heterodimer was estimated to be 30 +/- 10, and this value differs largely from the natural abundance for the chlorine isotope.
    An experimental scheme to discern homo and heterodimers is proposed here. By looking at fragments in the (HCl)(2) dimer photodissociation using a Doppler-selected time-of-flight (TOF) technique, internal energy distribution of the [ClHCl] fragment was measured in 121.6 nm photodissociation. The TOF spectrum consists of fast and slow velocity components for the dissociated H atoms. It is found that the slow H component that arises from the hydrogen escapes after many collisions. The fast H component that arises from the direct H escape without any collision, thus this component reflects an internal and/or electronic state of the counter part fragment, i.e. [ClHCl]. The vibrational structure of [ClHCl] was observed for the fast H component of the TOF spectrum. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI

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    16
    Citation
    (Scopus)
  • The reaction of O(D-1) with H2O, D2O monomers and clusters and the intracomplex reaction in N2O-X2O (X=H,D) photo-initiated at 193 and 212.8 nm

    K Imura, M Veneziani, T Kasai, R Naaman

    JOURNAL OF CHEMICAL PHYSICS   111 ( 9 ) 4025 - 4031  1999.09

     View Summary

    The reaction of O(D-1) with water and water clusters was re-examined. We monitored the nascent product state distributions in the reaction photo-initiated by the dissociation of N2O at 193 and 212.8 nm, and the corresponding photo-initiated intracluster reaction. The study at two different dissociation wavelengths and the use of D2O allowed us to obtain direct information on the effect of initial collision kinetic energy on the energy distribution in the product. Based on the new results obtained we conclude that the reaction of O(D-1) with water occurs through abstraction mechanism with a relatively short lived collision complex. In the case of the intracluster reaction, we have indication that more internal energy is deposited in the N-2 moiety, compared to the dissociation of an isolated N2O. In addition the results indicate that the reaction between the oxygen atom and the water in the complex involved the formation of a short lived collision complex, with a lifetime of probably only few rotations of OH. (C) 1999 American Institute of Physics. [S0021-9606(99)01732-8].

    DOI

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    7
    Citation
    (Scopus)
  • Focusing of DCl and HCl dimers by an electrostatic hexapole field: The role of the tunneling motion

    K Imura, T Kasai, H Ohoyama, R Naaman

    JOURNAL OF CHEMICAL PHYSICS   110 ( 1 ) 355 - 358  1999.01

     View Summary

    The focusing of HCl and DCl dimers was observed using a 2-m-long electrostatic hexapole field. The results indicate the existence of two types of species. The first is the homodimers, either the (HCl)-Cl-35-(HCl)-Cl-35 or the (DCl)-Cl-35-(DCl)-Cl-35, for which the data indicate a fast tunneling motion. The second is the heterodimers, (HCl)-Cl-35-(HCl)-Cl-37 or (DCl)-Cl-35-(DCl)-Cl-37, that do not show evidence for significant tunneling motion on the time scale of the experiment. In the case of HCl dimers, even at relatively high fields, only one species could be focused, the heterodimer. The electric dipole moments for both (DCl)(2) isotopomers were determined to be 1.5+/-0.2 D, which is the same value as observed for (HCl)(2). (C) 1999 American Institute of Physics. [S0021-9606(98)02048-0].

    DOI

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    19
    Citation
    (Scopus)
  • Active Control of the Relative Population of 3P0 Fine-State in the Glow Discharge of a Supersonic Ar Beam

    Ryotaro Midorikawa, Hiroshi Ohoyama, Kohei Imura, Toshio Kasai

    Bulletin of the Chemical Society of Japan   70 ( 6 ) 1261 - 1265  1997

     View Summary

    An active control for changing the relative population of the 3P0 fine-state of Ar* in a supersonic beam was investigated in a glow discharge by adding a small amount of foreign gases to pure Ar gas. The Ar* mean velocity was determined to be constant at major positions of the time profile, except for a rise and the decay of the beam for all gas mixtures, and also pure Ar. The relative population of 3P0 decreased with the discharge potential for the addition of ethylene, cyclohexane, and benzene. However, the addition of N2 and CH4 and pure Ar, did not show such a 3P0 decrease. These dissimilar behaviors of the foreign mixed gases could be interpreted based on a difference in the ionization potential of the molecules. A useful application of this population control is discussed.

    DOI

    Scopus

  • Experimental determination of the dipole moment of HCl dimer using an electrostatic hexapole field

    K Imura, T Kasai, H Ohoyama, H Takahashi, R Naaman

    CHEMICAL PHYSICS LETTERS   259 ( 3-4 ) 356 - 360  1996.09

     View Summary

    HCl dimers were prepared in a pulsed supersonic beam of neat HCl. The dimers were focused in an electrostatic hexapole field. Using computer simulation, the focusing curve could be fit, assuming contributions from both first and second order Stark effects. The dipole moment, based on simulation, was found to be 1.5 +/- 0.1 D. The ability to observe an effective dipole moment in a system where the donor-acceptor tunneling is fast is surprising. It may indicate that the understanding of the interaction of floppy systems with hexapole field is not complete.

    DOI J-GLOBAL

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    18
    Citation
    (Scopus)
  • Observation of relative population change in the P-3(0) and P-3(2) states for Ar glow discharge formation

    K Imura, R Midorikawa, T Kasai, H Ohoyama, DC Che

    CHEMISTRY LETTERS   ( 4 ) 299 - 300  1996

     View Summary

    The formation ratio of the two spin-orbit states, P-3(0)/P-3(2), of the metastable argon, Ar*, was investigated by the glow discharge of a pulsed Ar supersonic beam. The P-3(0)/P-3(2) ratio decreased with the increase of the glow discharge potential V-g, by which the electron bombardment initiates the discharge. The observed V-g-dependence clearly showed an inverse behavior against V-g as compared with that in the conventional electron impact by low beam densities.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • 貴金属微粒子の波動関数イメージングと動的近接場分光

    井村考平, 岡本裕巳

    日本分光学会誌   2006 ( 55 ) 161 - 172

    DOI

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Presentations

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Research Projects

  • 光場制御と強結合によるナノ光増強場の高度化と機能開拓

    日本学術振興会  科学研究費助成事業

    Project Year :

    2023.04
    -
    2027.03
     

    井村 考平, 長谷川 誠樹

  • 超螺旋光によるナノキラル光場の創成とその可視化

    日本学術振興会  科学研究費助成事業

    Project Year :

    2023.04
    -
    2025.03
     

    井村 考平

  • Optical properties control of advanced functional nanomaterials using spatially selective chemical reactions

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2022.06
    -
    2024.03
     

  • Active control of photo-excited states and energy propagation with manipulated optical fields

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

    Project Year :

    2020.04
    -
    2024.03
     

  • Visualization and optical control of electromagnetic resonances in mesostructures

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)

    Project Year :

    2020.07
    -
    2022.03
     

    Imura Kohei

     View Summary

    In the subwavelength scale meso-materials, electromagnetic fields are significantly amplified by elementally excitations, and consequently novel optical properties can be realized. However, for that purpose, deep understanding of the electromagnetic fields induced in the meso-material is indispensable. In this study, we performed ultra-precise nano-imaging of the meso-materials and clarified spatial characteristics of the electromagnetic fields in the materials. In addition, we achieved giant optical response of the meso-material by using new light-matter interaction. The developed methods are promising for creating new functions in the meso-materials.

  • Advancement and network formation of the project Photosynergetics by international collaboration

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2015.11
    -
    2019.03
     

    MIYASAKA Hiroshi

     View Summary

    Photochemistry takes important roles in the light energy conversion, material synthesis and many photofunctional materials. However, there are three common limitations, such as Kasha’s rule, annihilation of excitons and the restriction in optical transition, for the effective utilization of the light energy. This program aimed to accelerate the research development of the Grant-in-Aid for Scientific Research on Innovative Area “Photosynegetics”, which started with the purpose to overcome above limitations, via sending and inviting researchers between the project groups and international institutes and holding international workshops. As a result of these activities, 182 international coauthored papers are published and the CNRS program “Internationally associated laboratory, LIA” was adopted with France. These results indicate that present activities have contributed not only to the short-term development but also to the long-term international collaborations.

  • Application of Cooperative Excitation into Innovative Molecular Systems with High-Order Photofunctions

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2014.07
    -
    2019.03
     

    Miyasaka Hiroshi

     View Summary

    Photochemistry takes important roles in the light energy conversion, material synthesis and many photofunctional materials. However, there are three common limitations, such as Kasha’s rule, annihilation of excitons and the restriction in optical transition, for the effective utilization of the light energy. This program aimed to accelerate the research development of the Grant-in-Aid for Scientific Research on Innovative Area “Photosynegetics”, which started with the purpose to overcome above limitations, via advice on the research of each member of the project, proposal of joint research among members, information sharing among members, management of symposia, and public relations. As a result of these activities, the excellent research results (965 papers), effective joint researches (>100 and 96 papers), the presentation award young researchers (216) were obtained.

  • Spatio-temporal coherent control of excited states in metal nanostructures and its application to control of light propagation

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2016
    -
    2019
     

    Imura Kohei

     View Summary

    Precise control of material functions and energy transfer is one of the ultimate challenges in science and technology. This enables to develop new methods for efficient use of energy, arithmetic processing, and information technology, and will contribute to solving energy and environmental problems. In this study, we clarified the basic principle to control the function of nanomaterials in both time and space manner. In addition, we have achieved active control of light propagation.

  • Advanced Function Control of Photochemical Reactions Using Mesoscopic Structures

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2014
    -
    2018
     

    Kohei Imura, IMAEDA Keisuke

     View Summary

    Elementary excitations in meso-structures squeeze light spatially and result in the amplified optical fields. We developed various near-field spectroscopic imaging system to visualize spatial distributions of the localized optical fields in the vicinity of the metallic meso-structures. We applied the localized fields to amply and modulate linear and non-linear optical processes of various molecules. We revealed that the localized fields enable to excite photochemical processes that are not accessible by the plane wave illumination. We also developed space-selective chemical reaction methods to synthesize photo-functional materials, and demonstrated the control of the photoluminescence and the guiding of the light in the desired way.

  • Control of Molecular Recognition by Light-induced Force and Development of Ultrafast Highly-sensitive Biosensor

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2014.04
    -
    2017.03
     

    Iida Takuya, IMURA KOHEI

     View Summary

    The purpose of this research was to elucidate the control principle of the biomolecular recognition by the light-induced force, and we aimed at development of a rapid and highly sensitive innovative biosensor. Especially, utilizing the synergetic effect of light-induced force and light-induced convection under laser irradiation, we have revealed that the submillimeter macroscopic assembly can be formed via the acceleration of a specific binding of probe nanomaterial and zmol-level DNA as a target biomolecule. The obtained result would be the foundation of a label-free, ultrafast, highly-sensitive biosensor based on the optical guiding process, and would be used for the progress of technologies that are strongly required in medical and food related fields, for example, the early diagnosis in genetic diseases and allergies, and the separation methods of drugs.

  • Development of advanced cathode-luminescence microscope

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2016
    -
    2017
     

    IMURA Kohei, KAMURA Yoshio

     View Summary

    Optical characterizations with a high spatial resolution are fundamental importance to unravel photo-physical processes in nanomaterials. Optical microscope is of great use for this purpose. However, spatial resolution is limited by diffraction of light. In this study, we developed an advanced cathode-luminescence spectro-microscope, which achieves a nanometer spatial resolution, by combining a phase-step luminescence spectroscopy with a low vacuum compatible scanning electron microscope. We applied the developed method to various nanometerials and clarified its effectiveness and versatility. Moreover, We developed a novel fabrication protocol for organo-luminescent nanoarchitectures. The methods developed in this study are promising for detailed characterization of the nanomaterials.

  • Spatio-temporal characteristics and control of coupled excited states in nano-dot arrays

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2010.04
    -
    2015.03
     

    OKAMOTO Hiromi, NARUSHIMA Tetsuya, IMURA Kohei, NISHIYAMA Yoshio, JIANG Yuqiang, LIM Jong Kuk, KOWAKA Yasuyuki, WU Hui Jun, HASHIYADA Shun

     View Summary

    This research aimed principally at revealing space-time structures of optical fields in metal nanostructures and plasmonic interactions that determine the field structures, through near-field optical imaging and analysis. We found characteristic optical field structures in 1- and 2-dimensional array structures of metal nanoparticles, and the results were intepreted in terms of a simple model of inter-particle interaction. We also obtained some intriguing results on ultrafast dynamics and other basic nano-optical characteristics of metal nanostructures. We further extend the research to studies on optical activity in nanospace. A novel near-field circular dichroism microscope was constructed, and local optical activity of metal nanostructures was visualized. We found that metal nanoparticles yield locally very strong optical activity, and that even highly symmetric achiral nanostructures gave local optical activity.

  • Development of near-field refection microspectroscope

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2014
    -
    2015
     

    Imura Kohei

     View Summary

    Near-field optical microscope achieves a nanometer spatial resolution, and is of great use for studying optical properties of nanomaterials. However, the method is not fully compatible to conventional spectroscopic methods. For example, near-field reflection spectroscopy was not established because of large background light with respect to a tiny near-field signal. We proposed to extract near-field signal from the observed reflection by using phase-stepping technique. We developed near-field reflection microscope and applied it to study optical properties of a silver nanoplate. The microscope improves the signal to noise greatly and enables to recover a tiny signal from observed reflected light. Near-field reflection image of the plate shows periodic spatial oscillations attributable to plasmon modes. The microscope enables to study nanostructures not only on the transparent substrate but also on the opaque substrate, and has a great potential as a general analytical tool.

  • Spatio-temporal control of photo-excited states in nanoparticle assemblies

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2012
    -
    2015
     

    Immure Kohei

     View Summary

    Optical control of material functions is important for efficient energy use. In this project, we proposed to establish novel excitation schemes to control functions of nanomaterials. For this purpose, we developed an ultrafast nano-imaging method by combining ultrafast spectroscopy with a near-field optical microscope. By using this method, we visualized spatio-temporal dynamics of elementary excitations in gold nanostructures and found that spatial features of the excited states undergo ultrafast periodic oscillations. We also examined optical properties of gold nanoparticle assemblies, and found that unique optical properties are induced due to plasmon-plasmon interactions. The results indicate that optical properties of gold nanoparticle assembly can be controlled by the phase-modulation of excitation pulse and tuning of plasmon-plasmon interactions. The methods above can be extended to various nanosystems, and open up new route for optical control of material functions.

  • プラズモニックメタマテリアルのナノ分光研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(新学術領域研究(研究領域提案型))

    Project Year :

    2013
    -
    2014
     

    井村 考平

     View Summary

    本研究では,メタマテリアルの構成要素であるプラズモンのモード間相互作用を実空間実時間で可視化し,相互
    作用がメタマテリアルの機能に及ぼす効果とその機構を解明することを目的としている。本年度は,ガラス基板上に周期ナノ構造およびランダムナノ構造体を作製し,その特性を近接場光学顕微鏡により可視化しプラズモン間のカップリング機構の詳細を解明することを目標とした。これを実現するために,金薄膜に励起される伝播型プラズモンと局在型プラズモンの相互作用を近接場光学顕微鏡の(I)イルミネーション,(C)コレクション,散乱(S)の3つのモードで測定した。透過およびに非線形光学測定の結果は,可視化される像が測定モードに依存して変化することが明らかとなった。例えば,Iモードで得られる像は,Cモードの像に比べてシャープな特徴が多く可視化されること,伝播型プラズモンと局在型プラズモンの相互作用を考慮しないと説明できない特性が

  • Development of single molecule absorption spectroscopy

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2012
    -
    2013
     

    IMURA Kohei

     View Summary

    Absorption spectroscopy is useful for molecular identifications, while its sensitivity is limited by intensity fluctuation of light source and noises of a detector. In order to improve the sensitivity, miniaturization of the illumination area down to nanometer scale is promising since the absorbance is inversely proportional to the illumination area. In this study, to reduce the illumination area, local illumination of the apertured near-field probe was utilized. The near-field fiber probe was fabricated, and the operation principle for enhancing the sensitivity was examined. Absorption sensitivity was enhanced with this technique, and the improvement enables to obtain valuable spectroscopic information on nanomaterials with wide spectral range. . A single molecular sensitivity has not yet been achieved, however, by improving the fabrication of the near-field probe it will be realized in near future.

  • Visualization of plasmon wave functions by a scanning tunneling electron microscop

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2010
    -
    2011
     

    IMURA Kohei

     View Summary

    In this project, we proposed to excite plasmons by the electron injection and to visualize the plasmon wavefunctions by a scanning tunneling electron microscope. We developed the microscope based on the scanning near-field optical microscope. The microsope can achieve a spatial resolution less than a few tens nm in topography, optical, and tunnel electron images. We found that a characteristic spatial feature was visualized in the tunnel electron image for the gold thin film. Alternatively, we visualize plasmon wavefunctions excited in various nanostructures by using the scanning near-field optical microscope.

  • Dynamic visualization and control of photochemical reaction fields based on near-field spectroscopic imaging

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2007
    -
    2010
     

    OKAMOTO Hiromi, IMURA Kohei, KITAJIMA Masahiro, NARUSHIMA Tetsuya, HARADA Yosuke

     View Summary

    Optical fields can be confined and enhanced in a nanometric space by the use of metal nanostructures, which potentially create novel photochemical reaction fields and photoenergy conversion systems. As a basis toward achieving that, we visualized nanoscale optical field distributions in various metal nanostructures to reveal the optical characteristics, using a near-field optical microscope that enables a spatial resolution far beyond that of a conventional optical microscope. We obtained guidelines for designing nanostructures that efficiently generate and control enhanced localized optical fields.

  • Wavefunctions and excited-state dynamics of nanoparticle systems

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2006
    -
    2009
     

    OKAMOTO Hiromi, IMURA Kohei, KITAJIMA Masahiro

     View Summary

    Fundamental technologies were developed to achieve spectroscopic measurements with very high spatial resolution and time resolution at the same time. Studies were also done to obtain fundamental knowledge for exploring wave characteristics of excited states of nanomaterials and manipulating them. We succeeded in visualization of wavefunctions of photo-excited states and spatial distributions of photons for various metal nanostructures, and revealed novel optical characteristics through the analyses of the observed images. We also obtained information on dynamics via time- and space-resolved spectroscopic measurements.

  • 表面増強ラマン散乱の分光評価に関する研究

    Project Year :

    2006
    -
    2009
     

  • Development of a novel ultrafast near-field optical method having spatio-temporal control functions for excitation and detection

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2006
    -
    2008
     

    IMURA Kohei

  • ナノ構造体に関する近接場イメージング

    Project Year :

    2006
    -
    2008
     

  • 近接場分光法による素励起の波動関数のイメージング

    科学研究費助成事業(分子科学研究所)  科学研究費助成事業(萌芽研究)

    Project Year :

    2005
    -
    2006
     

     View Summary

    本年度は,貴金属ナノ微粒子とその集合体に関する近接場分光イメージングを継続して行った。
    ナノロッドやナノプレートの長波長領域におけるプラズモン共鳴を実測する目的で,近赤外域の分光測定系を完成させ,試料測定を開始したが,これに関して新たな情報を得るには至っていない。今後解析を進め,アスペクト比の大きな金属ナノ微粒子のプラズモン共鳴に関して詳細な議論が可能になるものと考えている。
    球状金ナノ微粒子の凝集構造に関して,昨年度に引き続き増強電場の空間分布の近接場イメージングを行った。微粒子間空隙に増強電場が集中し,ラマン活性も同じ部位に集中していることをイメージングにより明確にし,プラズモン共鳴による表面増強ラマン散乱の機構についての実験的な根拠を与えることができた。また,微粒子を二次元的に最密充填構造で敷き詰めた試料についても増強電場のイメージングを行い,充填構造の欠陥部位で電場の増強とラマン活性が顕著になるな

  • プラズモンの可視化に関する研究

    Project Year :

    2005
    -
     
     

  • メゾスコピック領域における金微粒子を用いた空間的エネルギー伝播の直接観測

    科学研究費助成事業(分子科学研究所)  科学研究費助成事業(若手研究(B))

    Project Year :

    2004
    -
    2005
     

     View Summary

    本研究は、鎖状に連結した金微粒子を用いて空間選択的に注入されたエネルギーがどのような時間・空間スケールで伝播するのか、伝播に伴うエネルギーの緩和や散逸がどのような時間スケール・素過程を通して起こるのかを解明することを目的としている。
    本年度前半は、まず鎖状および二次元的に連結した金微粒子がどのような光学的特徴を持つか,エネルギーがどのような時間・空間スケールで伝播するのかを、微粒子内部の位置まで分解して(空間分解能約50nm)解明することを目的として、近接場透過スペクトルと近接場二光子誘起発光測定を行った。
    近接場透過スペクトル測定から、波長以下の空間スケールで起こる光子と物質の相互作用について電磁気学的に基本的な情報を得た。また,連結微粒子全体のコヒーレントな励起過程が存在することを明らかにした。さらに,連結微粒子を棒状微粒子とみなしたときに,エネルギーの伝播長が励起波長に依存することを古典電磁気学計算

  • Molecular Science of Excitation Transfer Dynamics by Dynamic Near-Field Spectroscopy

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2004
    -
    2005
     

    OKAMOTO Hiromi, IMURA Kohei

     View Summary

    Scanning near-field optical microscope enables optical measurements and observations with a spatial resolution far beyond the diffraction limit of light. This allows us to investigate spectroscopic characteristics with spatially resolving the positions point by point in nanoparticles. In this research, we have developed experimental methods and apparatuses of dynamic near-field spectroscopy, and applied them to time- and space-dynamics of excited states for plasmons in metal nanoparticles as well as molecular nanostructures.
    For the studies of surface plasmon resonances in noble metal nanoparticles, we obtained notable achievements described in the following.
    We utilized linear transmission/scattering as well as nonlinear two-photon excitation measurements in the near field to observe the nanoparticles, and found that the wavefunction of the plasmon excitation resonant with the incident radiation field can be optically visualized.
    We succeeded in femtosecond time-resolved near-field imaging for gold nanorods, and found that the relaxation process depends on the position although the nanorod is a homogeneous crystalline material.
    In the aggregated nanoparticles, strong electric-fiel

  • 大極不均一電場法によりサイズと構造を選別した分子クラスターの立体ダイナミクス研究

    日本学術振興会  科学研究費助成事業

    Project Year :

    1998
    -
    1999
     

    井村 考平

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Misc

  • Light Confinement of CsPbBr3 Microplates Studied by Near-Field Imaging

    長谷川誠樹, 林ひな, 井村考平

    日本化学会春季年会講演予稿集(Web)   103rd  2023

    J-GLOBAL

  • Plasmon resonance condition dependence of nano-antenna enhancement effect at the center of Bull’s eye plasmonic chip

    篠原洸羽, 名和靖矩, 長谷川誠樹, 井村考平, 田和圭子

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   70th  2023

    J-GLOBAL

  • Nonlinear Photoluminescence Properties of Gold Nanoplates Studied by Azimuthally and Radially Polarized Light Excitation

    長谷川誠樹, 市川帆乃香, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   70th  2023

    J-GLOBAL

  • Microscopic study on photoinduced spectral changes of gold nanorods

    林直哉, 川嶋健哉, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   17th  2023

    J-GLOBAL

  • Study on plasmon-exciton interaction in gold nanorod-MoS2 hybrid structure

    甲斐亨, 長谷川誠樹, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   17th  2023

    J-GLOBAL

  • Cylindrical polarization dependence of nonlinear excitation image on gold nanoplate

    長谷川誠樹, 市川帆乃香, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   17th  2023

    J-GLOBAL

  • Optical Properties of Plasmon-Exciton Strong Coupling studied by Near-Filed Optical Microscopy

    長谷川誠樹, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   69th  2022

    J-GLOBAL

  • Control of Antenna Effect Based on the Emission Enhancement of fluorescent nanoparticle with Bull’s eye-Type Plasmonic Chips

    永末智也, 篠原洸羽, 長谷川誠樹, 井村考平, 田和圭子

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   69th  2022

    J-GLOBAL

  • Photoluminescence enhancement of carbon dots by localized surface plasmons and photonic crystals

    佐藤陸, 香村惟夫, 井村考平

    日本化学会春季年会講演予稿集(Web)   102nd  2022

    J-GLOBAL

  • Second harmonic generation from gold nanoplates excited by spatially modulated light

    長谷川誠樹, 市川帆乃香, 飯島遥, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   16th  2022

    J-GLOBAL

  • Effect of spatially modulated light excitation on two-photon induced photoluminescence from gold nanoplates

    市川帆乃香, 長谷川誠樹, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   16th  2022

    J-GLOBAL

  • Nonlinear Optical Properties of Si Nanoparticle-Au Nano-Line Hybrid Structures

    四方田真輝, 長谷川誠樹, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   83rd  2022

    J-GLOBAL

  • Optical Microscopy of Localized Modes Confined in CsPbBr3 Perovskite Microplates

    林ひな, 長谷川誠樹, 井村考平

    日本分光学会年次講演会(CD-ROM)   2022  2022

    J-GLOBAL

  • Sensitive Fluorescence Imaging with a Bull’s Eye-type Plasmonic Chip

    田和圭子, 井村考平

    村田学術振興財団年報   ( 35 )  2021

    J-GLOBAL

  • Enhanced Fluorescence Antenna Effect Depending on Center Structure of Bull’s eye-Type Plasmonic Chips

    永末智也, 篠原洸羽, 長谷川誠樹, 井村考平, 田和圭子

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   82nd  2021

    J-GLOBAL

  • Development of optical micro-spectroscopic method using the phase stepping technique

    深田将史, 白山大樹, 井村考平

    日本分光学会年次講演会(CD-ROM)   2021  2021

    J-GLOBAL

  • Near-Field Imaging of Two-Dimensional Plasmonic Chip

    今枝佳祐, 田和圭子, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   67th  2020

    J-GLOBAL

  • Photoluminescence properties of Au-Cu2O nanohybrid structures

    板東廣朗, 長谷川誠樹, 井村考平

    日本分光学会年次講演会(CD-ROM)   2020  2020

    J-GLOBAL

  • Chemical and physical effect on optical characteristics of gold nanorods

    川嶋健哉, 今枝佳祐, 井村考平

    日本分光学会年次講演会(CD-ROM)   2020  2020

    J-GLOBAL

  • Enhancements of excitation and radiation fields near single gold mesoplates

    長谷川誠樹, 今枝佳祐, 井村考平

    日本分光学会年次講演会(CD-ROM)   2020  2020

    J-GLOBAL

  • Near-Field Spectral and Spatial Properties of Plasmons Excited on Gold Nanocubes

    乙部隼也, 井村考平

    日本分光学会年次講演会(CD-ROM)   2020  2020

    J-GLOBAL

  • カーボンドットの空間選択的合成とその光物性制御

    香村惟夫, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   13th  2019

    J-GLOBAL

  • 金ナノロッドの光誘起形状制御

    川嶋健哉, 三沢悟, 今枝佳祐, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   13th  2019

    J-GLOBAL

  • 金ナノロッドにおける光近接場空間分布の観測

    鈴木啓真, 今枝佳祐, 溝端秀聡, 井村考平

    日本分光学会年次講演会   2019  2019

    J-GLOBAL

  • 金属ナノ構造体に誘起されるプラズモンの化学的制御

    川嶋健哉, 今枝佳祐, 井村考平

    日本分光学会年次講演会   2019  2019

    J-GLOBAL

  • Near-field spatial and spectral characteristics of two-dimensional plasmonic meso-structures

    今枝佳祐, 井村考平

    光化学   50 ( 3 )  2019

    J-GLOBAL

  • 電子線照射を利用したカーボンドットの空間選択的生成

    香村惟夫, 井村考平

    ナノ学会大会講演予稿集   17th  2019

    J-GLOBAL

  • 金ナノキューブにおけるプラズモンの立体的可視化

    乙部隼也, 松浦拓哉, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   80th  2019

    J-GLOBAL

  • 近接場分光イメージングによるプラズモン-エキシトン相互作用の究明

    横澤旭美, 松浦拓哉, 長谷川誠樹, 今枝佳祐, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   80th  2019

    J-GLOBAL

  • 化学合成金ナノプレートにおけるプラズモン増強第二高調波発生

    飯島遥, 上田慎二, 長谷川誠樹, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   80th  2019

    J-GLOBAL

  • 金ナノプレートプラズモンにおける表面ラフネス依存性

    財間詩乃, 今枝佳祐, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   80th  2019

    J-GLOBAL

  • 金三角形プレートプラズモンの静的および動的空間特性の可視化

    今枝佳祐, 長谷川誠樹, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   79th   ROMBUNNO.20p‐224A‐1  2018.09

    J-GLOBAL

  • 金ナノプレート近傍における蛍光増強過程の究明

    長谷川誠樹, 今枝佳祐, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   65th   ROMBUNNO.18p‐P9‐9  2018.03

    J-GLOBAL

  • 金三角形プレートに励起されるプラズモン固有モードの可視化

    今枝佳祐, 長谷川誠樹, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   65th   ROMBUNNO.17a‐A402‐2  2018.03

    J-GLOBAL

  • 電子線照射を用いたポリスチレン薄膜の光ナノパターニング

    香村惟夫, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   65th   ROMBUNNO.18a‐A402‐6  2018.03

    J-GLOBAL

  • 構造規整された極細金ナノロッドの生成過程と局在表面プラズモン共鳴

    高畑遼, 山添誠司, 山添誠司, 山添誠司, 小安喜一郎, 小安喜一郎, 井村考平, 佃達哉, 佃達哉

    分子科学討論会講演プログラム&要旨(Web)   12th  2018

    J-GLOBAL

  • 電子線描画と自己組織化を用いた金属ナノハイブリッド構造の作製とその非線形光学特性

    村井日奈子, 香村惟夫, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   12th  2018

    J-GLOBAL

  • 電子線誘起化学反応を利用した機能性有機化合物の空間選択的生成とその光学特性

    香村惟夫, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   12th  2018

    J-GLOBAL

  • 電子線誘起化学反応を用いた有機分子の発光特性制御

    香村惟夫, 井村考平

    日本分光学会年次講演会   2018  2018

    J-GLOBAL

  • 六角金メソプレートのプラズモンの可視化と近接場分光特性

    松浦拓哉, 長谷川誠樹, 今枝佳祐, 井村考平, 井村考平

    日本分光学会年次講演会   2018  2018

    J-GLOBAL

  • 金三角形メソプレートにおけるプラズモン固有モードの近接場イメージング

    今枝佳祐, 長谷川誠樹, 井村考平

    日本分光学会年次講演会   2018  2018

    J-GLOBAL

  • ピッカリングエマルジョン法を用いた金ナノ粒子集合構造体の作製とその光物性の解明

    長谷川花恵, 長谷川誠樹, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   79th  2018

    J-GLOBAL

  • 群論を用いた金属ナノ構造体の光学特性の解明

    上田慎二, 長谷川誠樹, 市川陽一, 上野貢生, 三澤弘明, 岡本裕巳, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   79th  2018

    J-GLOBAL

  • 単一ナノ構造の光吸収と散乱特性評価法の検討

    白山大樹, 今枝佳祐, 井村考平

    日本分光学会年次講演会   2018   147  2018

    J-GLOBAL

  • 時間分解蛍光イメージング法を用いたプラズモン-分子相互作用の研究

    長谷川誠樹, 今枝佳祐, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   78th  2017

    J-GLOBAL

  • 精密制御された金属ナノ粒子集合体の二光子誘起発光特性

    平柳祐太, 井村考平

    日本分光学会年次講演会   2017  2017

    J-GLOBAL

  • 金属ナノ構造体における光熱変換効果の顕微分光研究

    三沢悟, 井村考平

    日本分光学会年次講演会   2017  2017

    J-GLOBAL

  • 酸化亜鉛サブマイクロ球の光学特性

    須田祥功, 井村考平

    日本分光学会年次講演会   2017  2017

    J-GLOBAL

  • 液液界面に作製した金ナノ粒子薄膜の光学特性と光化学反応性

    神保敦子, 西角友維, 井村考平

    日本化学会春季年会講演予稿集(CD-ROM)   97th  2017

    J-GLOBAL

  • 金ナノ粒子二光子発光における励起特性の究明

    馬昭明, 平柳祐太, 井村考平

    日本化学会春季年会講演予稿集(CD-ROM)   97th  2017

    J-GLOBAL

  • 酸化亜鉛サブマイクロ球の調製とその線形および非線形光学特性

    須田祥功, 香村惟夫, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   11th  2017

    J-GLOBAL

  • 液液界面に作製した金ナノ粒子薄膜の光学特性の化学的制御

    神保敦子, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   11th  2017

    J-GLOBAL

  • 電子線・紫外線照射ポリスチレンマイクロ構造体の光学特性の究明

    香村惟夫, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   11th  2017

    J-GLOBAL

  • 金属ナノ構造体における二光子励起過程の顕微分光による研究

    MA Shomin, 今枝佳祐, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   64th  2017

    J-GLOBAL

  • 近接場透過イメージングによる近接場光の空間とスペクトル特性の究明

    鈴木啓真, 今枝佳祐, 溝端秀聡, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   78th  2017

    J-GLOBAL

  • 光照射した金ナノ粒子近傍の熱空間分布の可視化

    三沢悟, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   78th  2017

    J-GLOBAL

  • 二光子発光計測による精密制御金ナノ粒子集合体における光電場増強効果の究明

    平柳祐太, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   78th  2017

    J-GLOBAL

  • 金属ナノ構造を用いたジアセチレン分子膜の光重合の研究

    降幡耀子, 長谷川誠樹, 坂本章, 岡本裕巳, 井村考平

    日本分光学会年次講演会   2017  2017

    J-GLOBAL

  • ジアセチレン分子膜の二光子重合におけるプラズモン光電場効果の究明

    降幡耀子, 長谷川誠樹, 今枝佳祐, 坂本章, 岡本裕巳, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   11th  2017

    J-GLOBAL

  • 近接場反射・透過分光測定による金属ナノ構造体の光吸収と散乱特性の評価

    溝端秀聡, 長谷川誠樹, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   11th  2017

    J-GLOBAL

  • 電子線および紫外線照射ポリスチレン球自己集合体の顕微分光研究

    香村惟夫, 井村考平

    日本化学会春季年会講演予稿集(CD-ROM)   96th  2016

    J-GLOBAL

  • 金薄膜上銀ナノ粒子の非線形光学応答

    森山和憲, 大島拓也, 鳥本司, 井村考平

    日本化学会春季年会講演予稿集(CD-ROM)   96th  2016

    J-GLOBAL

  • 時間分解顕微分光法による金ナノ粒子の非線形光学特性の究明

    MA Shomin, 井村考平

    日本化学会春季年会講演予稿集(CD-ROM)   96th  2016

    J-GLOBAL

  • 色素援用非線形イメージング法による金ナノ粒子プラズモンの可視化

    今枝佳祐, 井村考平

    日本化学会春季年会講演予稿集(CD-ROM)   96th  2016

    J-GLOBAL

  • 電子線照射ポリスチレン自己集合体の二光子励起特性の究明

    香村惟夫, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   10th  2016

    J-GLOBAL

  • 近接場光学顕微鏡による金ナノ構造体の一光子発光特性の究明

    今枝佳祐, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   10th  2016

    J-GLOBAL

  • カソードルミネッセンスと顕微分光計測によるポリスチレン自己集合体の光物性の研究

    香村惟夫, 井村考平

    ナノ学会大会講演予稿集   14th  2016

    J-GLOBAL

  • 近接場反射顕微分光法の開発と金属ナノ構造体の分光特性の究明

    溝端秀聡, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   63rd  2016

    J-GLOBAL

  • 近接場顕微分光手法の拡張とプラズモン研究への応用

    井村考平, 今枝佳祐, 溝端秀聡, 西山嘉男, 岡本裕巳

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   77th  2016

    J-GLOBAL

  • カソードルミネッセンスと非線形分光計測を用いた酸化亜鉛ナノワイヤーの顕微分光研究

    香村惟夫, 井村考平

    日本分光学会年次講演会   2015  2015

    J-GLOBAL

  • 金薄膜上金ナノ粒子の非線形光学特性の究明

    森山和憲, 井村考平

    日本分光学会年次講演会   2015  2015

    J-GLOBAL

  • 共焦点光学顕微鏡とカソードルミネッセンス顕微鏡を用いた酸化亜鉛ナノ構造体の光学特性に関する研究

    香村惟夫, 井村考平

    日本化学会講演予稿集   95th ( 2 )  2015

    J-GLOBAL

  • 金ナノ粒子六角配列構造における光電場の最適化と増強分光法への応用

    内田多佳子, 井村考平

    日本化学会講演予稿集   95th ( 2 )  2015

    J-GLOBAL

  • 金ナノ粒子薄膜の作製とそのプラズモン誘起光化学過程への応用

    西角友維, 溝端秀聡, 井村考平

    日本化学会講演予稿集   95th ( 2 )  2015

    J-GLOBAL

  • 顕微分光法による金ナノ粒子の二光子発光特性の研究

    馬昭明, 井村考平

    日本化学会講演予稿集   95th ( 2 )  2015

    J-GLOBAL

  • 金ナノロッドにおけるプラズモンダイナミクスの時間分解イメージング

    西山嘉男, 成島哲也, 成島哲也, 井村考平, 岡本裕巳, 岡本裕巳

    日本化学会講演予稿集   95th ( 2 )  2015

    J-GLOBAL

  • テンプレートフリー金ナノ粒子配列構造体の作製とその光励起空間モードの可視化

    内田多佳子, 今枝佳祐, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   9th  2015

    J-GLOBAL

  • レーザー加工による金属メソ円形構造体の作製とその顕微分光研究

    平野祐樹, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   9th  2015

    J-GLOBAL

  • 近接場イメージング手法の拡張と金属ナノ構造の励起空間モードの可視化

    井村考平, 溝端秀聡, 今枝佳祐

    分子科学討論会講演プログラム&要旨(Web)   9th  2015

    J-GLOBAL

  • 金ナノ粒子の線形光学特性と非線形光学特性の相関の究明

    MA Shomin, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   9th  2015

    J-GLOBAL

  • カソードルミネッセンス分光顕微鏡の開発とナノ光物性研究への応用

    香村惟夫, 内田多佳子, 井村考平

    ナノ学会大会講演予稿集   13th  2015

    J-GLOBAL

  • 金ナノ粒子複合体の自己組織的周期構造における光応答の理論解析

    吉川貴康, 内田多佳子, 田村守, 田村守, 井村考平, 飯田琢也

    光物性研究会論文集   26th  2015

    J-GLOBAL

  • Real Space and Real Time Observation of Plasmon Wavepacket Dynamics in Single Gold Nanorod

    Y. Nishiyama, T. Narushima, K. Imura, H. Okamoto

    ULTRAFAST PHENOMENA XIX   162   691 - 693  2015

     View Summary

    Plasmon dynamics in a single gold nanorod was visualized by ultrafast time-resolved near-field optical microscopy. On excitation of multiple plasmon modes, transient near-field images exhibit prominent temporal change that reflects a characteristic behavior of coherent superposition of the excited plasmons.

    DOI

  • Real Space and Real Time Observation of Plasmon Wavepacket Dynamics in Single Gold Nanorod

    Y. Nishiyama, T. Narushima, K. Imura, H. Okamoto

    ULTRAFAST PHENOMENA XIX   162   691 - 693  2015

     View Summary

    Plasmon dynamics in a single gold nanorod was visualized by ultrafast time-resolved near-field optical microscopy. On excitation of multiple plasmon modes, transient near-field images exhibit prominent temporal change that reflects a characteristic behavior of coherent superposition of the excited plasmons.

    DOI

  • 2013年日本光学会の研究動向 7.近接場光学

    井村考平

    光学   43 ( 4 ) 156 - 158  2014.04

    CiNii J-GLOBAL

  • Near-Field Optics

    井村 考平

    光学 = Japanese journal of optics : a publication of the Optical Society of Japan, the Japan Society of Applied Physics   43 ( 4 ) 156 - 158  2014.04

    CiNii

  • 金ナノロッドにおけるプラズモン波束ダイナミクスの時間分解近接場イメージング

    西山嘉男, 成島哲也, 成島哲也, 井村考平, 岡本裕巳, 岡本裕巳

    日本分光学会年次講演会   2014  2014

    J-GLOBAL

  • 超高速時間分解近接場顕微測定による金ナノロッドにおけるプラズモン波ダイナミクスの時空間観測

    西山嘉男, 成島哲也, 成島哲也, 井村考平, 岡本裕巳, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   8th  2014

    J-GLOBAL

  • レーザー加工による金属マイクロ構造体の作製とその光学特性の究明

    平野祐樹, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   8th  2014

    J-GLOBAL

  • シリカコート金ナノ粒子を用いた蛍光増強とレーザー発振の試み

    西角友維, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   8th  2014

    J-GLOBAL

  • 動的近接場分光法による凹凸金薄膜プラズモンの位相緩和測定

    今枝佳祐, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   8th  2014

    J-GLOBAL

  • 金ナノ粒子配列の作製とその光電場増強度の究明

    内田多佳子, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   8th  2014

    J-GLOBAL

  • 金ナノ粒子集合体の作製とその顕微分光観察

    内田多佳子, 市川陽一, 井村考平

    ナノ学会大会講演予稿集   12th  2014

    J-GLOBAL

  • ZnOマイクロディスクの近接場顕微分光とその独立成分分析

    武内麻未, 井村考平

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   61st  2014

    J-GLOBAL

  • 金ナノロッドにおけるプラズモン位相緩和過程の時空間観測

    西山嘉男, 成島哲也, 成島哲也, 井村考平, 岡本裕巳, 岡本裕巳

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   61st  2014

    J-GLOBAL

  • 金ナノ粒子集合体におけるプラズモン間相互作用の究明

    市川陽一, 上野貢生, 三澤弘明, 岡本裕巳, 岡本裕巳, 井村考平

    日本分光学会年次講演会   2014  2014

    J-GLOBAL

  • 相補的金属ナノ構造における近接場分光特性の究明:可視域におけるバビネの原理の検証

    溝端秀聡, 上野貢生, 三澤弘明, 岡本裕巳, 岡本裕巳, 井村考平

    応用物理学会秋季学術講演会講演予稿集(CD-ROM)   75th  2014

    J-GLOBAL

  • 網目状金ナノ構造体におけるプラズモン特性の究明

    市川陽一, 上野貢生, 三澤弘明, 岡本裕巳, 岡本裕巳, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   8th  2014

    J-GLOBAL

  • 酸化亜鉛マイクロディスクにおけるキャビティモードの可視化

    武内麻未, 井村考平

    日本分光学会年次講演会   2013  2013

    J-GLOBAL

  • 近接場光学顕微鏡を用いた金ナノクラスターの発光特性に関する研究

    大瀬戸彬, 井村考平

    日本分光学会年次講演会   2013  2013

    J-GLOBAL

  • 酸化銅(I)ナノキューブの顕微分光研究

    大村淳, 井村考平

    日本分光学会年次講演会   2013  2013

    J-GLOBAL

  • ナノ構造薄膜におけるプラズモン光増強場の生成機構

    森本仁嗣, 井村考平

    日本分光学会年次講演会   2013  2013

    J-GLOBAL

  • 金ナノ構造体における動的空間特性の可視化

    今枝佳祐, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   7th  2013

    J-GLOBAL

  • 六角形銀マイクロプレートのプラズモンモードの可視化

    溝端秀聡, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   7th  2013

    J-GLOBAL

  • チューブ状シアニンJ会合体の近接場顕微分光

    牧田賢彦, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   7th  2013

    J-GLOBAL

  • 超高速時間分解近接場顕微測定による金ナノロッドのプラズモン位相緩和過程の観測

    西山嘉男, 成島哲也, 成島哲也, 井村考平, 岡本裕巳, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   7th  2013

    J-GLOBAL

  • 近接場光学顕微鏡を用いた高感度吸収分光測定法の構築

    堤内勇貴, 溝端秀聡, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   7th  2013

    J-GLOBAL

  • 金薄膜における二光子発光の動的制御

    今枝佳祐, 井村考平

    日本化学会講演予稿集   93rd ( 2 )  2013

    J-GLOBAL

  • 酸化亜鉛マイクロ構造体における第二高調波発生の観測

    武内麻未, 井村考平

    日本化学会講演予稿集   93rd ( 2 )  2013

    J-GLOBAL

  • 超高速(~15fs)近接場測定によるプラズモン応答の時空間観測

    西山嘉男, 成島哲也, 成島哲也, 井村考平, 岡本裕巳, 岡本裕巳

    応用物理学会春季学術講演会講演予稿集(CD-ROM)   60th  2013

    J-GLOBAL

  • 金ナノ粒子正方配列の近接場分光特性

    市川陽一, 今枝佳祐, 上野貢生, 三澤弘明, 岡本裕巳, 岡本裕巳, 井村考平

    日本化学会講演予稿集   93rd ( 2 )  2013

    J-GLOBAL

  • Near-field opticalmicroscopy of plasmonic nanostructures

    Kohei Imura, Hiromi Okamoto

    Handbook of Nano-Optics and Nanophotonics     527 - 562  2013.01

     View Summary

    Plasmonic metal nanostructures exhibit unique optical properties, and fundamental studies of them are relevant to wide range of research areas. Unique characteristics of the plasmonic nanostructures originate from the localized optical fields and are closely related to spatiotemporal properties of plasmon waves. In this chapter, visualization of plasmon wave functions and localized optical fields by scanning near-field optical microscopy is described.

    DOI

  • Near-Field Optical Microscopy of Localized Surface Plasmons Excited in Noble Metal Nanostructures

    IMURA Kohei, OKAMOTO Hiromi

    レーザー研究   40 ( 8 ) 571 - 578  2012.08

    CiNii J-GLOBAL

  • Near-Field Optical Microscopy of Localized Surface Plasmons Excited in Noble Metal Nanostructures

    井村 考平, 岡本 裕巳

    レーザー研究   40 ( 8 ) 571 - 578  2012.08

    CiNii

  • ボイド型ナノ構造体を用いた高感度分子検出法の開発

    井村考平

    旭硝子財団研究助成成果発表会   2012   38 - 39  2012.07

    J-GLOBAL

  • 酸化亜鉛マイクロ構造体の近接場イメージング

    武内麻未, 井村考平

    ナノ学会大会講演予稿集   10th   207  2012.06

    J-GLOBAL

  • 超短パルス(&lt;20fs)近接場顕微分光装置の開発と金ナノ粒子のプラズモン位相緩和の観測

    西山嘉男, WU Hui Jun, 成島哲也, 井村考平, 岡本裕巳

    日本化学会講演予稿集   92nd ( 2 ) 239  2012.03

    J-GLOBAL

  • 近接場光学顕微鏡による二重壁シアニンJ会合体の研究

    牧田賢彦, 井村考平

    日本化学会講演予稿集   92nd ( 2 ) 288  2012.03

    J-GLOBAL

  • Development of ultrasensitive molecular detection methods using nanovoid structures

    井村考平

    旭硝子財団助成成果報告書(Web)   2012  2012

    J-GLOBAL

  • 動的近接場分光法による表面増強ラマン散乱増強機構の検討

    今枝佳祐, 井村考平

    応用物理学関係連合講演会講演予稿集(CD-ROM)   59th  2012

    J-GLOBAL

  • 超短パルス(<20fs)近接場分光装置によるプラズモン位相緩和の観測

    西山嘉男, JUN Wu Hui, JUN Wu Hui, 成島哲也, 成島哲也, 井村考平, 井村考平, 岡本裕巳, 岡本裕巳

    応用物理学関係連合講演会講演予稿集(CD-ROM)   59th  2012

    J-GLOBAL

  • 近接場光学顕微鏡による銀ナノキューブの分光観察

    斉藤太郎, 井村考平, 井村考平

    日本化学会講演予稿集   92nd ( 2 )  2012

    J-GLOBAL

  • 超短パルス(<20fs)近接場顕微分光測定による金ナノ構造体のプラズモン位相緩和過程の観測

    西山嘉男, JUN Wu Hui, JUN Wu Hui, 成島哲也, 成島哲也, 井村考平, 井村考平, 岡本裕巳, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   6th  2012

    J-GLOBAL

  • 先端的非線形近接場光学顕微鏡の開発とそのナノ物質系への応用

    大村淳, 井村考平, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   6th  2012

    J-GLOBAL

  • 金ナノクラスターの顕微分光研究

    大瀬戸彬, 井村考平, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   6th  2012

    J-GLOBAL

  • 波形整形パルスによるプラズモン光電場の制御

    今枝佳祐, 井村考平, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   6th  2012

    J-GLOBAL

  • 近接場光学顕微鏡による酸化亜鉛マイクロ構造体の励起モードの可視化

    武内麻未, 井村考平, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   6th  2012

    J-GLOBAL

  • 近接場光学顕微鏡によるプラズモニック増強場の生成機構の検討

    森本仁嗣, 井村考平, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   6th  2012

    J-GLOBAL

  • プラズモニック物質における光電場の可視化と制御

    井村考平, 井村考平, 今枝佳祐, 上野貢生, 上野貢生, 三澤弘明, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   6th  2012

    J-GLOBAL

  • 近接場光学顕微鏡(SNOM)を使いこなす

    井村 考平

    化学と工業 = Chemistry and chemical industry   64 ( 6 ) 470 - 471  2011.06

    CiNii

  • ジアリールエテン閉環-開環反応におけるプラズモン光増強場の効果

    溝端秀聡, 岡本裕巳, 井村考平, 井村考平

    日本化学会講演予稿集   91st ( 2 )  2011

    J-GLOBAL

  • 金ナノ薄膜の動的近接場分光研究

    今枝佳祐, 井村考平, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   5th  2011

    J-GLOBAL

  • プラズモニック物質の波動関数の光制御とその応用

    井村考平, 井村考平

    日本化学会講演予稿集   91st ( 1 )  2011

    J-GLOBAL

  • 二光子誘起フォトクロミック反応における金属ナノ粒子のプラズモン共鳴効果

    溝端秀聡, 岡本裕巳, 井村考平, 井村考平

    日本分光学会年次講演会   2011  2011

    J-GLOBAL

  • ナノスケール構造を持つ金薄膜の近接場顕微分光

    今枝佳佑, 井村考平, 井村考平

    日本分光学会年次講演会   2011  2011

    J-GLOBAL

  • 金薄膜上のナノヴォイドにおける蛍光増強の顕微分光研究

    市川悟史, 岡本裕巳, 岡本裕巳, 井村考平, 井村考平

    分子科学討論会講演プログラム&要旨(Web)   5th  2011

    J-GLOBAL

  • 金薄膜上のナノヴォイドにおける光電場の可視化

    井村考平, 井村考平, 上野貢生, 上野貢生, 三澤弘明, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   5th  2011

    J-GLOBAL

  • ジアリールエテン二光子誘起反応におけるプラズモン共鳴効果

    溝端秀聡, 井村考平, 井村考平, 岡本裕巳

    分子科学討論会講演プログラム&amp;要旨(Web)   4th   ROMBUNNO.4P065 (WEB ONLY)  2010

    J-GLOBAL

  • 低次元系金属構造体における局在光電場分布の可視化

    岡本裕巳, 井村考平

    日本物理学会講演概要集   65 ( 1 )  2010

    J-GLOBAL

  • 近接場分光法による金属ナノ構造の光子場イメージング

    岡本裕巳, 岡本裕巳, 井村考平

    応用物理学関係連合講演会講演予稿集(CD-ROM)   57th  2010

    J-GLOBAL

  • 近接場顕微分光に基づく光反応場の動的可視化・制御

    井村考平, 岡本裕巳, 岡本裕巳

    応用物理学関係連合講演会講演予稿集(CD-ROM)   57th  2010

    J-GLOBAL

  • ジアリールエテンの閉環-開環反応におけるナノロッドプラズモン共鳴の効果

    溝端秀聡, 岡本裕巳, 井村考平, 井村考平

    日本分光学会ナノ分光部会シンポジウム講演予稿集   2010  2010

    J-GLOBAL

  • 21pHL-14 FDTD Simulation of Plasmon Distribution on Gold Nano Rod

    Nakamura Hiroaki, Sawada Keiji, Maruoka Teruto, Imura Kohei, Saiki Toshiharu, Okamoto Hiromi

    Meeting Abstracts of the Physical Society of Japan   65 ( 1 ) 183 - 183  2010

    DOI CiNii J-GLOBAL

  • 21pHL-14 FDTD Simulation of Plasmon Distribution on Gold Nano Rod

    Nakamura Hiroaki, Sawada Keiji, Maruoka Teruto, Imura Kohei, Saiki Toshiharu, Okamoto Hiromi

    Meeting Abstracts of the Physical Society of Japan   65 ( 0 ) 766 - 766  2010

    CiNii J-GLOBAL

  • Near-Field Optical Imaging of Localized Plasmon Resonances in Metal Nanoparticles

    Hiromi Okamoto, Kohei Imura

    Molecular Nano Dynamics: Vol. I: Spectroscopic Methods and Nanostructures / Vol. II: Active Surfaces, Single Crystals and Single Biocells   1   39 - 54  2009.11

    DOI

  • Near-field optical imaging of enhanced electric fields and wavefunctions

    岡本 裕巳, 井村 考平

    Function & materials   29 ( 11 ) 49 - 55  2009.11

    CiNii

  • 近接場顕微分光に基づく金属ナノ構造における局在光電場分布の可視化

    岡本裕巳, 井村考平

    応用物理学関係連合講演会講演予稿集   56th  2009

    J-GLOBAL

  • プラズモニック物質のナノ分光研究

    井村考平, 井村考平, 岡本裕巳

    SPMを用いたナノ分光/センシング技術 理研シンポジウム 講演予稿集 平成21年    2009

    J-GLOBAL

  • 貴金属ナノ構造体の二光子誘起発光:発光特性と発光メカニズム

    井村考平, 井村考平, KIM Young Chae, KIM Seongyong, JEONG Dae Hong, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   3rd  2009

    J-GLOBAL

  • 近接場顕微分光による金ナノ微粒子が相互作用した光電変換素子の研究

    原田洋介, 井村考平, 岡本裕巳, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   3rd  2009

    J-GLOBAL

  • 液晶分子が結合した金ナノロッド間に働く配列相互作用

    堀田裕康, 新谷理恵, 田中英一, 森田剛, 畠山義清, 西川恵子, 井村考平, 岡本裕巳, 沼尾茂悟, 西信之, 中野博文, 日野和之

    分子科学討論会講演プログラム&要旨(Web)   3rd  2009

    J-GLOBAL

  • 立体規則性ポリ(3-ヘキシルチオフェン)ナノファイバーの近接場分光イメージング測定

    小林徹, 田中伸樹, 坂本章, 井村考平, 岡本裕巳

    分子科学討論会講演プログラム&要旨(Web)   3rd  2009

    J-GLOBAL

  • Finite-Difference Time-Domain Simulation on Imaging of Gold Nanorods by Near-field Scanning Optical Microscope

    NAKAMURA Hiroaki, TAMURA Yuichi, ITO Atsushi, SAWADA Keiji, SAIKI Toshiharu, OKAMOTO Hiromi, IMURA Kohei

    日本シミュレーション学会大会発表論文集   27   361 - 364  2008.06

    CiNii J-GLOBAL

  • Imaging of Plasmon Wavefunctions in Noble Metal Nanoparticles by Near-field Optical Microscopy

    IMURA Kohei, OKAMOTO Hiromi

    J. Surf. Sci. Soc. Jpn.   29 ( 6 ) 336 - 343  2008.06

     View Summary

    Scanning near-field optical microscopy facilitates the studies on optical properties of nanomaterials beyond the diffraction limit of light. It enables us to reveal the optical properties point by point on the nanomaterials. In this article, we review our recent works on optical properties and their spatial features of localized plasmons in noble metal nanoparticles, revealed by various near-field optical techniques. We show that photonic local density-of-states or optical fields on the nanoparticles are visualized by using near-field linear and non-linear spectroscopic imaging techniques. We also show that the plasmon wavefunction resonant with the incident field is visualized by the near-field methods. Finally, we present spatio-temporal behaviors of the nanoparticles upon the photoexcitation visualized by near-field time-resolved imaging technique. We analyze the origin of the characteristic transient images and discuss energy dissipation processes of the nanoparticles.

    DOI CiNii J-GLOBAL

  • 近接場光学顕微鏡による金ナノ微粒子低次元配列における増強電場分布

    島田透, 井村考平, 岡本裕巳, 北島正弘

    日本化学会講演予稿集   88th ( 1 )  2008

    J-GLOBAL

  • 近接場分光顕微鏡によるポリジアセチレンLB膜の二光子光重合と二光子誘起発光の研究

    坂本章, 森和彦, 井村考平, 岡本裕巳

    光化学討論会講演要旨集   2008  2008

    J-GLOBAL

  • エクストリームフォトニクス研究 近接場非線形分光法による金ナノ構造の研究

    井村考平, KIM Si Il, KIM Sehum, 岡本裕巳

    エクストリームフォトニクス研究 第7回理研・分子研合同シンポジウム 平成20年    2008

    J-GLOBAL

  • 銀ナノワイヤーにおける二光子誘起発光とプラズモンモードイメージ

    井村考平, 岡本裕巳, KIM Young Chae, JEONG Dae Hong

    応用物理学関係連合講演会講演予稿集   54th ( 3 )  2007

    J-GLOBAL

  • 金ナノ微粒子単層膜における局在電場と構造との関係

    島田透, 井村考平, 井村考平, HOSSAIN M. K., HOSSAIN M. K., 岡本裕巳, 岡本裕巳, 北島正弘, 北島正弘, 北島正弘

    応用物理学会学術講演会講演予稿集   68th ( 3 )  2007

    J-GLOBAL

  • 近接場顕微分光法の高度化

    井村考平, 岡本裕巳

    分子科学討論会講演要旨集(CD-ROM)   1st  2007

    J-GLOBAL

  • 単一金ナノ粒子による色素の蛍光増強の形状依存性

    堀本訓子, 井村考平, 岡本裕巳

    日本化学会講演予稿集   87th ( 1 )  2007

    J-GLOBAL

  • 近接場光学顕微鏡を用いた金ナノ粒子単層膜に対する2光子励起確率及び透過イメージング

    島田透, 井村考平, HOSSAIN M. K., 岡本裕巳, 北島正弘

    日本化学会講演予稿集   87th ( 1 )  2007

    J-GLOBAL

  • 近接場分光イメージングの新手法の開拓とナノ物質の局所励起と波動関数の研究

    井村考平, 井村考平

    日本化学会講演予稿集   87th ( 1 )  2007

    J-GLOBAL

  • 近接場分光顕微鏡によるポリジアセチレンLB膜の二光子光重合と二光子蛍光の研究

    坂本章, 森和彦, 井村考平, 岡本裕巳

    分子科学討論会講演要旨集(CD-ROM)   1st  2007

    J-GLOBAL

  • 金ナノ構造体の近接場分光

    井村考平, 岡本裕巳, 上野貢生, 三澤弘明

    分子科学討論会講演要旨集(CD-ROM)   1st  2007

    J-GLOBAL

  • 金属ナノ構造のプラズモンモード

    井村考平, 岡本裕巳, 上野貢生, 三澤弘明

    エクストリームフォトニクス研究-バイオイメージング 第5回理研・分子研合同シンポジウム 平成19年    2007

    J-GLOBAL

  • 静的および動的近接場分光法による貴金属微粒子の波動関数イメージング

    井村考平, 岡本裕巳

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

    J-GLOBAL

  • 金属微粒子系の光励起と近接場イメージング

    岡本裕巳, 井村考平

    光化学討論会講演要旨集   2006  2006

    J-GLOBAL

  • 金属ナノ微粒子系における電場増強と近接場測定

    井村考平, 堀本訓子, 岡本裕巳

    エクストリームフォトニクス研究-エクストリーム波長の発生と応用 第3回理研・分子研合同シンポジウム 平成18年    2006

    J-GLOBAL

  • Plasmon Wavefunction Imaging and Dynamic Near-Field Optical Microscopy of Noble Metal Nanoparticles

    井村考平, 岡本裕巳

    分光研究   55 ( 3 )  2006

    J-GLOBAL

  • シゾフィラン-単層カーボンナノチューブ複合体の近接場二光子発光分光

    井村考平, 岡本裕巳, 沼田宗典, 新海征治

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

    J-GLOBAL

  • 金微粒子会合体における電場分布と表面増強ラマン散乱の近接場イメージング

    井村考平, 岡本裕巳, HOSSAIN M. K., 北島正弘

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

    J-GLOBAL

  • 単一金ナノ微粒子の時間分解近接場分光

    井村考平, 岡本裕巳

    化学反応討論会講演要旨集   22nd  2006

    J-GLOBAL

  • 金微粒子二量体における近接場二光子誘起発光と表面増強ラマン散乱

    井村考平, 岡本裕巳, HOSSAIN Mohammad K., 北島正弘

    応用物理学関係連合講演会講演予稿集   53rd ( 3 )  2006

    J-GLOBAL

  • Imaging of Plasmons in Gold Nano-Particles by Dynamic Near-Field Spectroscopy

    OKAMOTO Hiromi, IMURA Kohei

    rle   34 ( 3 ) 224 - 229  2006

     View Summary

    Optical properties of metal nanoparticles, especially gold nanorods in this review, are investigated by static and dynamic near-field microscopy and spectroscopy. We describe instrumentation for the dynamic near-field spectroscopy which enables less than 100-fs temporal resolution at the tip of the apertured near-field probe. We show that wavefunctions of the plasmon modes resonant with the incident light are imaged by near-field transmission imaging as well as by near-field two-photon induced photoluminescence measurements. We also show the results of the ultrafast near-field imaging of gold nanorods, where the dynamics after photoexcitation strongly depends on the position on the nanorod.

    DOI CiNii J-GLOBAL

  • Near-field two-photon-induced Photoluminescence from gold nanorods and nanoplates and imaging of plasmon modes

    Imura Kohei, Okamoto Hiromi

    The Review of Laser Engineering   34 ( 0 ) 16 - 17  2006

    CiNii

  • nano

    Kitajima Masahiro, Hossain Mohammad Kammal, Shimada Toru, Imura Kohei, Okamoto Hiromi

    Abstract of annual meeting of the Surface Science of Japan   26 ( 0 ) 161 - 161  2006

     View Summary

    金ナノ粒子2次元単層構造における局在プラズモン励起に関する近接場分光

    CiNii

  • 金ナノロッド・ナノプレートのプラズモンモードイメージングと二光子誘起発光

    井村考平, 永原哲彦, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2005   2A17  2005.09

    J-GLOBAL

  • 単一金ナノロッドによる色素の蛍光増強:近接場光学顕微鏡による観察

    堀本訓子, 井村考平, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2005   3P110  2005.09

    J-GLOBAL

  • プラズモン共鳴帯の先鋭化 : 微粒子配列による効果

    井村 考平

    化学と工業 = Chemistry and chemical industry   58 ( 7 ) 846 - 846  2005.07

    CiNii

  • Dynamics and plasmon mode imaging of gold nanorods

    IMURA Kohei, NAGAHARA Tetsuhiko, OKAMOTO Hiromi

    應用物理   74 ( 4 ) 492 - 496  2005.04

    CiNii J-GLOBAL

  • 金ナノロッドにおける二光子誘起発光の特性

    井村考平, 永原哲彦, 岡本裕巳

    応用物理学関係連合講演会講演予稿集   52nd ( 3 ) 1166  2005.03

    J-GLOBAL

  • Scanning Near-Field Optical Microscopic Study of Porphyrin Nano-Wire

    永原哲彦, 井村考平, 岡本裕巳, 小沢寛晃, 小川琢治

    日本化学会講演予稿集   85th ( 1 ) 326  2005.03

    J-GLOBAL

  • Scanning Near-Field Optical Microscopic Study of Thin Films of Self-Assembled Porphyrin

    永原哲彦, 井村考平, 岡本裕巳, 小黒あかね, 今堀博

    日本化学会講演予稿集   85th ( 1 )  2005

    J-GLOBAL

  • Two-photon induced photoluminescence from gold nanorods

    井村考平, 永原哲彦, 岡本裕巳

    日本化学会講演予稿集   85th ( 1 )  2005

    J-GLOBAL

  • 金ナノプレートの近接場プラズモンモードイメージング

    井村考平, 永原哲彦, 岡本裕巳

    光化学討論会講演要旨集   2005  2005

    J-GLOBAL

  • 金ナノロッドの時間分解近接場分光

    井村考平, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2005  2005

    J-GLOBAL

  • ポルフィリン単分子ワイヤーのSNOMによる研究

    永原哲彦, 井村考平, 岡本裕巳, 小沢寛晃, 小川琢治

    光化学討論会講演要旨集   2005  2005

    J-GLOBAL

  • Scanning Near-Field Optical Microscopic Study of Thin Films of Porphyrin J-Aggregates(2) Site-Specificity of the Dynamics

    永原哲彦, 井村考平, 岡本裕巳

    日本化学会講演予稿集   84th ( 1 )  2004

    J-GLOBAL

  • Near-field spectroscopy of a gold nanoparticle: Corralation between its structure and spectroscopic characteristics

    井村考平, 永原哲彦, 岡本裕巳

    日本化学会講演予稿集   84th ( 1 )  2004

    J-GLOBAL

  • 金ナノロッドのプラズモンモードマッピングと時間分解近接場分光

    井村考平, 永原哲彦, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2004  2004

    J-GLOBAL

  • ポンプ・白色プローブ時間分解近接場顕微鏡のポルフィリンJ-会合体への適用

    永原哲彦, 井村考平, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2004  2004

    J-GLOBAL

  • 近接場分光法による波動関数イメージング

    井村考平, 永原哲彦, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2004  2004

    J-GLOBAL

  • ポルフィリンJ-会合体薄膜の走査型近接場光学顕微鏡による時間・空間分解分光

    永原哲彦, 井村考平, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2003  2003

    J-GLOBAL

  • 金ナノ粒子の近接場分光とダイナミクス

    井村考平, 永原哲彦, 岡本裕巳

    分子構造総合討論会講演要旨集(CD-ROM)   2003  2003

    J-GLOBAL

  • The scanning near-field optical microscopic study of the thin film of Porphyrin J-aggregates

    永原哲彦, 井村考平, 岡本裕巳

    日本化学会講演予稿集   83rd ( 1 )  2003

    J-GLOBAL

  • ポルフィリンJ-会合体薄膜の時間分解走査型近接場光学顕微鏡による研究

    永原哲彦, 井村考平, 岡本裕巳

    ナノ学会大会講演予稿集   2003  2003

    J-GLOBAL

  • 超高速近接場分光システムの開発とそのJ会合体への適用

    井村考平, 永原哲彦, 岡本裕巳

    分子構造総合討論会講演要旨集   2002  2002

    J-GLOBAL

  • 二次元ペニングイオン化電子分光法と古典トラジェクトリー計算を用いたHe*(23S)-HCl反応系の研究

    井村考平, 岸本直樹, 大野公一

    化学反応討論会講演要旨集   18th  2002

    J-GLOBAL

  • Two-Dimensional Penning Ionization Electron Spectroscopy of Monohalogenobenzenes.

    井村考平, 岸本直樹, 大野公一

    日本化学会講演予稿集   79th ( 1 ) 229  2001.03

    J-GLOBAL

  • Structure Selection of Al(C6H6) Clusters by Using an Electrostatic Hexapole Technique.

    井村考平, 川島孝啓, 大山浩, 笠井俊夫

    分子構造総合討論会講演要旨集   2000  2000

    J-GLOBAL

  • Dependence of the N2O-H2O photo-induced intra-cluster reaction upon the excitation wavelength.

    井村考平, VENEZIANI M, NAAMAN R, 笠井俊夫

    分子構造総合討論会講演要旨集   1999  1999

    J-GLOBAL

  • Structure Selection of Organometallic Cluster using Hexapole Field.

    井村考平, 川島孝啓, 大山浩, 笠井俊夫

    分子構造総合討論会講演要旨集   1999  1999

    J-GLOBAL

  • Reactivity of HCl dimer-Penning ionization reaction.

    井村考平, 大山浩, 笠井俊夫

    化学反応討論会講演要旨集   15th  1999

    J-GLOBAL

  • The tunneling effect on the reactivity and structure of the HCl dimers.

    井村考平, 笠井俊夫, 大山浩, NAAMAN R

    日本化学会講演予稿集   74th ( 1 )  1998

    J-GLOBAL

  • Isotope effect on the proton tunneling in the hydrogen-bonded cluster.

    井村考平, 笠井俊夫, 大山浩, NAAMAN R

    分子構造総合討論会講演要旨集   1997  1997

    J-GLOBAL

  • Size-selection of the HCl clusters and determination of its dipole moment by uisng an electrostatic hexapole field.

    井村考平, 笠井俊夫, 大山浩, NAAMAN R

    分子構造総合討論会講演要旨集   1996  1996

    J-GLOBAL

  • Grid-potential-dependence of the 3P0/3P2 population ratio of the glow discharge formation in the pulsed Ar beam.

    井村考平, 笠井俊夫, CHE D-C, 緑川良太郎, 大山浩

    日本化学会講演予稿集   69th ( 1 )  1995

    J-GLOBAL

  • Observation of the chemiluminesence, with variation of the spin-orbit state ratio 3P0/3P2 by a glow-discharge of pulsed Ar beam.

    井村考平, 緑川良太郎, 笠井俊夫, 大山浩

    化学反応討論会講演要旨集   11th  1995

    J-GLOBAL

▼display all

Industrial Property Rights

  • 発光体の製造方法,発光体,真偽判別体,メモリ媒体,及びマスクパターン形成方法

    井村考平, 香村惟夫

    Patent

  • 近接場分光装置

    井村 考平, 溝端 秀聡

    Patent

    J-GLOBAL

 

Syllabus

▼display all

Teaching Experience

  • 光物理化学特論,メソ化学演習,実践的化学知セミナー

    早稲田大学大学院  

  • 物理化学C, 物理化学演習,光物理化学, 化学C, 物理化学実験, 理工学基礎実験1A, 2B

    早稲田大学  

 

Social Activities

  • ミクスチャンネル(愛知県岡崎市)

    2006
    -
     

Sub-affiliation

  • Faculty of Science and Engineering   Graduate School of Advanced Science and Engineering

Research Institute

  • 2022
    -
    2024

    Waseda Research Institute for Science and Engineering   Concurrent Researcher

  • 2022
    -
    2024

    Waseda Center for a Carbon Neutral Society   Concurrent Researcher

Internal Special Research Projects

  • 軸対称偏光による金属ナノ物質の光学特性制御

    2023  

     View Summary

     金属ナノ物質に励起される自由電子の集団電子振動(プラズモン)により,非線形光学過程を効率的に誘起することが可能である。偶数次の非線形光学過程は,空間反転対称性のある物質系では励起することができない一方,空間反転対称性のない系や,物質表面では反転対称性が破れるため,これを励起することが可能である。金属ナノ物質における第二高調波発生の直線偏光に対する依存性については明らかになりつつある。光の伝播方向に垂直な断面方向において軸対称となる(軸対称)偏光に対する非線形光学特性については十分に解明されていない。本研究では,金属ナノ物質を対象とし,その第二高調波や非線形発光の軸対称偏光依存性から,光励起電場の空間対称性と偏光特性の相関解明を目指した。 清浄なガラス基板に化学合成した金ナノプレートを分散させて測定試料とした。試料の形状と光学特性は,それぞれ電子顕微鏡と光学顕微鏡を用いて単粒子レベルで評価した。試料の非線形発光の励起には,モードロックチタンサファイヤレーザーを光源として用いた。励起光の偏光は,波長板と偏光コンバータを用いて調整した。金ナノプレートを集束した軸対称偏光により照射し,試料からの非線形発光を対物レンズで集光し分光検出した。 試料からの発光を分光分析したところ,励起光よりも短波長の発光成分を含むことが明らかとなった。発光波長の分析や発光信号の励起光強度依存性から,発光には,第二高調波発生と二光子発光が含まれることが明らかとなった。非線形発光を検出し可視化した発光励起像は,入射偏光に顕著に依存すること,アジマスやラジアル偏光では特徴的な空間特性を示すことが明らかとなった。これらの励起像は,プレートのサイズにも顕著に依存する。観測される励起像の空間特性を解明するため,電磁気学計算を用いた解析を行なった。その結果,軸対称偏光の空間特性(対称性)によりプレートにおいて光励起されるプラズモンの固有モードが変化することが明らかとなった。

  • 金属ナノ集合構造における非線形光学特性の解明

    2022  

     View Summary

     金属ナノ構造体に光励起されるプラズモン共鳴は,光電場をナノスケールの空間に閉じ込め増強する。特に,金属ナノ構造集合体では,接合部位において光電場が著しく増強する。非線形光学過程は,光電場強度の増大とともに効率的に励起されるが,金属ナノ集合構造においては,その形状やサイズ依存性,また動的特性などに未解明な部分がある。本研究では,先端的光学顕微鏡を用いて,集合構造における非線形発光の形状やサイズ依存性,動的特性から,非線形発光の増強メカニズムを明らかにすることを目的とした。集合体の非線形発光や時間分解計測を行い,ナノ構造の集合形式により発光強度や緩和ダイナミクスが変化することが明らかとなった。

  • 金属メソ構造を用いたマルチセンシング

    2021  

     View Summary

     金属メソ構造に光励起される自由電子の集団電子振動であるプラズモンは,光をメソ構造近傍に時間的また空間的に閉じ込めて増強する。この増強電場は,分子からの蛍光やラマン散乱を増強することから,化学反応やセンシングへの応用が期待されている。これらの応用を実現するためには,メソ構造を大面積に分散しその機能を最適化する必要がある。また,分子の機能を多方面から評価するためには,複数の分光手法を組み合わせることが有用である。本研究では,金属メソ構造をガラス基板上に大面積に分散し,これをマルチセンシングに適用する手法の開発を目的とした。これまでにメソ構造の光増強効果とセンシング機能を明らかにした。

  • ナノ物質周期構造における近接場分光特性の研究

    2020  

     View Summary

     金属ナノ構造に光励起されるプラズモン共鳴は,光をナノ構造近傍に閉じ込めて局所的に増強する。,金属ナノ構造の周期構造では,個々のプラズモン共鳴に加えて周期性に由来する共鳴効果との干渉効果により,特に増強効果が強くなることが期待される。増強電場は,分子からの蛍光やラマン散乱を増強することから,超高感度化学センサーやナノ光学への応用が可能である。これらの応用を実現するためには,金属ナノ周期構造の近接場光学特性を深く理解する必要がある。本研究では,金ナノ粒子の集合構造を作製し,その近接場光学特性を顕微分光法により可視化し理解することを目的とした。

  • ナノ物質を用いた光温度計測法の開発

    2019  

     View Summary

     サブ波長スケールのナノ物質は,光電場を空間的に時間的に閉じ込めて光と物質の相互作用を増強する。光励起されたナノ物質は,輻射過程や無輻射過程を経て基底状態に戻る。このとき,ほとんどの物質において温度上昇が起こる。ナノ物質を光デバイスに応用するためには,物質の温度を正確に評価する必要がある。一方,接触法による測定は,対象物の温度に影響するため,ナノ物質の温度計測には不適である。光による計測は,非接触計測を可能とすることから,高精度な温度評価を実現する。本研究では,ナノ物質から放射される発光強度の温度依存性を明らかにし,これを用いた温度計測法を開発した。

  • ナノ構造体における光電磁場の可視化と電気磁気双極子相互作用による光学特性制御

    2018  

     View Summary

     金属ナノ構造体では,プラズモン共鳴により光電場とともに光磁場を増強する。光と物質の相互作用は,通常,光電場と電気双極子を基礎に理解される。増強磁場では,光磁場と磁気双極子の「相互作用が顕在化する。を本研究では,物質と光電場・光磁場との相互作用を可視化し,ナノ構造における光磁場応答の増大機構を解明することを目的とした。また,電気双極子と磁気双極子の相互作用を利用し,従来の枠組みを超える新しい光応答制御法を実現することを目的とした。これらの目的を実現するために,金属ナノプレートに励起されるプラズモンと希土類元素の磁気双極子遷移の相互作用を研究した。その結果,磁気双極子モードが局在励起されることを強く示唆される結果が得られた。

  • 光局所状態密度の高精度可視化法の開発

    2018  

     View Summary

     金属ナノ構造体において光励起される自由電子の集団電子運動は,光電場と電子の強結合状態を誘起する。光と電子の強結合状態は,光を時間的また空間的に閉じ込め,ナノ構造体近傍に著しく増強した光電磁場を誘起する。光増強場を応用に利用するためには,光増強場の時空間特性を理解することが本質的に重要である。光増強場は,ナノ構造体に誘起される光局所状態密度と強く相関することから,これを可視化することが光増強場の本質的理解と利用において不可欠である。本申請課題では,近接場光が発生する開口型近接場プローブの開口部分と試料表面の距離を高精度に制御して,近接場信号成分とファールード成分の分離検出を実現し,金属ナノ構造体における光局所状態密度分布の精密可視化法を確立することを目的とした。本研究では,金属の二次元構造体を研究対象とした。二次元構造体では,一次元構造体に比べてより多くの励起モードが存在し,その理解がより複雑となる。二次元構造体では,面内モードと面外モードが存在し,これらのモードの共鳴エネルギーは,近接していておりこれを分離検出することは通常困難である。本研究では,面外モードと面内モードの3次元的空間特性の違いに注目し,近接場プローブ開口部分と試料表面の距離を高精度に制御して,金属ナノプレートに誘起される励起モードの立体空間分布の高精度可視化を達成した。本研究により,面内モードの光増強場の発生メカニズムを詳細に解明した。

  • 近接場熱分光顕微鏡の開発

    2017  

     View Summary

    近接場光学顕微鏡は,近接場光を利用することで,回折限界を超える分光観察を可能とする顕微鏡である。これまでに,発光分光法,透過分光法,反射分光法などを組み合わせて,ナノ物質の光物性の研究に利用されてきている。一方,ナノ物質の光吸収特性を正確に評価するためには,透過分光法は利用できない。これは,ナノ物質では光散乱の寄与が大きく,純粋に光吸収を評価することができないためである。光吸収特性評価法として熱分光計測が有望である。本研究では,ナノスケールの空間分解能を実現する近接場熱分光顕微鏡開発を目的とした。金ナノ粒子をテスト試料として,熱分光計測を行い,原理的には計測が可能であることを確認した。

  • 金属ナノ構造体における光励起状態の機能制御

    2016  

     View Summary

    金属ナノ構造体に光励起される自由電子の集団振動は光電場を増強する。増強電場は,分子と強く相互作用しラマン散乱や蛍光を増強する。ナノ構造の光励起状態を効率的に利用するためには,その空間と時間特性を同時に可視化し理解する必要がある。本研究では,時間分解近接場光学顕微鏡を用いて金属ナノ構造体の光励起状態の動的空間特性の可視化を目的とした。金属ナノプレートの近接場透過像は,プレート形状とは異なる特徴的な空間特性を示す。理論計算から,観測される空間構造はプレートに励起される固有関数の二乗振幅に帰属されることを明らかにした。また,時空間計測を行い光励起状態の寿命がプレートの内部位置に依存して変化することを明らかにした。以上の結果は,金属ナノ構造体の光励起状態の利用において重要な指針となる。

  • カソードルミネッセンスを用いたキャビティーモードの可視化

    2015  

     View Summary

    本研究では,キャビティーモードの可視化を実現するために,走査型電子顕微鏡に対物レンズを組み込み,カソードルミネッセンス測光部を構築した。試料と対物レンズ間に調整機構を設け,微弱光計測を可能とした。また,検出系に光電子増倍管およびアレイ型分光システムを組み合わせ,シングルおよびマルチチャンネル測定を可能とした。測定試料として酸化亜鉛ナノ構造体を用いて測定系の最適化を行い,空間分解能100 nmを達成した。また,ノイズの軽減法について検討し,二次元フーリエ変換を用いたフィルタリングにより,キャビティーモードの可視化を可能とする高感度測定が実現されることを明らかとした。

  • プラキシトン状態の発現とその空間モードの可視化

    2014  

     View Summary

     貴金属ナノ構造体に光励起される素励起の一種であるプラズモンは,光をナノ空間に閉じ込め光電場を増強する。半導体ナノ構造体に光励起される素励起の一種であるエキシトンは,プラズモンと比べて寿命が長く,実現性や安定性など応用上の利点が多い。プラズモンとエキシトンが強結合する状態はプラキシトン状態と呼ばれ,二つの素励起の利点を合わせ持つ新しい光励起状態として注目を浴びつつある。本研究では,貴金属ナノ構造体と半導体ナノ構造体とが融合した構造を精密に作製し,それを単一レベルで研究することを目的とした。 プラズモン媒体として金ナノロッドをエキシトン媒体として半導体ナノドットを化学合成しこれらの混合試料を作製した。試料からの蛍光および二光子発光を検出し,プラキシトン状態に起因する空間特性を近接場光学顕微鏡を用いて可視化した。可視化像には,プラズモンモードに帰属される空間構造が観測されたが,明瞭なエキシトンの影響が認められなかった。このことは,プラズモンとエキシトンが弱結合状態であることを示す。

  • 動的近接場光学顕微鏡によるプラズモン誘起蛍光増強機構の解明

    2013  

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     貴金属ナノ構造体に光励起されるプラズモンは,光電場を空間的に局在化させ増強する。増強光電場は,近接して存在する分子の蛍光やラマン散乱を著しく増強する。プラズモン増強場は,蛍光やラマン散乱を介して微粒物質の検出を可能とすることから,化学センサーへの応用が期待されている。これを実現するためには,光電場の空間分布とプラズモンの動的特性を理解する必要がある。本課題では,プラズモンの寿命と蛍光寿命の相関を明らかにすることを研究目的にした。 プラズモンの動的空間構造を可視化するためには,プラズモンの位相緩和時間に迫る時間分解能とプラズモンの空間周波数よりも高い空間分解能を実現する必要がある。研究着手当時,空間分解能50 nm,時間分解能30 fsを実現する装置を開発していたが,時間分解能をさらに改善し最高で20 fsの時間分解能を達成することに成功した。また,これを用いて凹凸金ナノ薄膜を研究対象として,ポンプ・ポローブ時間相関波形計測を行った結果,プラズモンの位相緩和時間に関する知見を得ることに成功した。また,相関時間の分布測定法も開発し,得られた分布が,周波数領域の測定で得られた位相緩和時間の分布と定性的に一致することを明らかとした。さらに,位相緩和時間の分布とラマン散乱活性の分布の比較を行い,プラズモンの位相緩和時間とラマン増強度との間に正の相関が存在することを示唆する結果が得られている。 プラズモン増強場近傍での励起分子の蛍光挙動について詳細な知見を得るために,サブナノ秒の時間分解能を実現する近接場時間相関蛍光分光装置を開発した。この装置を用いて,金ナノボイド近傍に存在する分子の蛍光ダイナミクスを測定した結果,金ナノボイド辺縁部の光増強部位において,蛍光寿命の短寿命化が観測された。この結果は,励起分子の光放出過程にプラズモンが関与していることを示唆している。一方,光増強度とプラズモンの寿命の間にも相関関係が存在すると推測される。これまでのテスト計測から,光増強度とプラズモンの位相緩和時間の関係性についての知見を得ている。しかし,その物理的な解釈には至っていない。今後さらに詳細な測定を進めることで,光増強度とプラズモン位相緩和の相関関係,さらにはプラズモンの寿命と蛍光寿命の相関が明らかにする計画である。

  • プラズモニック物質による光増強反応場の創成

    2011  

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     ナノ構造体に励起されるプラズモンは,光電場をナノ構造体近傍に時間的空間的に閉じ込め,増強する。増強電場は,近接して存在する分子の蛍光やラマン散乱を増強することから,センサーなどへの応用が進んでいる。近年,光増強場を化学反応場として利用することが提案され,ナノ構造体の光化学反応への応用が試みられた。本研究では,光増強場を有するナノ構造体として,金属薄膜に作成した微小開口(ボイド)を利用することを提案した。 研究当初は,ナノ構造体が光化学反応場として確かに有効であるか不明な部分があったため,ナノロッドに発生する光増強場を用いて,これを確認することとした。光化学反応の評価には,ジアリールエテンの二光子誘起閉環―開環反応を利用した。また試料として,ナノロッド,ジアリールエテンの混合溶液と混合薄膜の二種類を用いた。これら二つの試料を用いた研究から,ロッドプラズモンを共鳴励起することで,光反応速度が増大することが明らかとなった。反応収量の光照射時間依存性の解析から,溶液および薄膜試料でそれぞれ反応速度が2倍,6倍増大することが明らかとなった。また,薄膜試料では光照射時間とともに反応収量の飽和が観測されたのに対し,薄膜試料では飽和現象は観測されなかった。光反応分子数の解析から,固体試料ではロッド近傍のみで反応が進行することが,また溶液試料ではロッド表面において繰り返し光化学反応が進行することが明らかとなった。 金属薄膜に作成したボイドを化学反応容器として利用することで,固体試料における反応速度の増大と溶液試料における反応場の繰り返し利用の両方の長所を利用することが可能である。ボイドは,ポリスチレン球をガラス基板上に分散後,金属膜をコートし,その後,ポリスチレン球を除去することで作成した。次に,高空間分解能での観察が可能な近接光学顕微鏡を用いてボイド近傍および内部で光増強場が発生することを確認した。また,この試料にジアリールエテンをスピンコードした試料を作成し,そのテスト計測から,ジアリールエテンに由来すると考えられるラマン散乱信号を確認した。ジアリールエテンの閉環体と開環体では,観測されるラマン散乱の波数が変化することから,試料の光反応前後のラマン計測により,化学反応量を見積もることができる。現在,ボイドの化学反応場としての有効性をラマン計測により評価することを検討している。

  • ナノボイド構造を用いた高感度分子検出

    2009  

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     貴金属微粒子ナノ構造体において光励起される自由電子の集団電子運動(局在プラズモン共鳴)は,極めて高い光電場増強場を創りだし,その近傍に存在する分子のラマン散乱を増強することから,超高感度分子検出の要素技術として注目されている。本申請では,この微粒子ナノ構造体と,金属部と誘電体部とが反転した構造であるボイド型ナノ構造体を,新たな超高感度分子検出要素,ラマン散乱増強素子として提案した。 研究計画では,当初,ポリスチレン球をテンプレートにして,金属薄膜にボイドを作製し,その分光評価,引き続いてラマン分光計測を行うことにしていたが,ガラス基板上でボリスチレン球の自己集積構造を作製するのに予想以上に時間を費やすことになった。また,研究室の試料作製や分光測定のための環境を整えるのにも非常に多くの時間を費やす必要があった。これらの理由から,研究の進展が遅れたが,最終的に上記の方法でボイドを試作し,当初の研究提案の核心である,原理検証を行うこと(ボイドにおけるプラズモン励起の確認)に成功した。また,電磁気学シミュレーションを用いて,ボイドにおけるプラズモン励起のメカニズムについて検討し,微粒子構造とボイド構造では,プラズモン励起の偏光特性が一致しないことが明らかとなった。詳細については,現在検討中あるが,プラズモン励起について一定の理解を得ることができた。これ以外にも,近接場顕微分光装置を自作し,その立ち上げ,基本動作の確認に成功した。顕微鏡の性能は,当初の計画以上であることが確認できた。 以上のように,当初の計画より遅れた部分はあるが,研究提案の原理検証に成功し,当初の研究計画の目標を達成できるところまで研究を進展させることができた。来年度の早い段階に,計測法としての定量評価を終え,本研究計画の最終目標を達成できる見込みである。

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