Faculty Profiles - KISHIDA Hideo

Papers - KISHIDA Hideo

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Trion formation in monolayer MoS2 observed via femtosecond time-resolved photoluminescence measurements Reviewed

Kota Nakama, Mitsuhiro Okada, Ryo Kitaura, Hideo Kishida, and Takeshi Koyama

Physical Review B Vol. 110 ( 23 ) page： 235412-1 - 235412-9 2024.12

Propagation of insulator-to-metal transition driven by photoinduced strain waves in a Mott material Reviewed International coauthorship International journal

Amano, T; Babich, D; Mandal, R; Guzman-Brambila, J; Volte, A; Trzop, E; Servol, M; Pastor, E; Alashoor, M; Larsson, J; Jurgilaitis, A; Pham, VT; Kroon, D; Ekström, JC; Ahn, B; Mariette, C; Levantino, M; Kozhaev, M; Tranchant, J; Corraze, B; Cario, L; Dolatabadi, M; Phuoc, VT; Sopracase, R; Guillon, M; Itoh, H; Kawakami, Y; Nakamura, Y; Kishida, H; Cailleau, H; Lorenc, M; Iwai, S; Janod, E

NATURE PHYSICS Vol. 20 ( 11 ) page： 1778 - 1785 2024.11

Anisotropic optical conductivity accompanied by a small energy gap in the one-dimensional thermoelectric telluride Ta₄SiTe₄ Reviewed

Fumiya Matsunaga, Yoshihiko Okamoto, Yasunori Yokoyama, Kanji Takehana, Yasutaka Imanaka, Yuto Nakamura, Hideo Kishida, Shoya Kawano, Kazuyuki Matsuhira, and Koshi Takenaka

Physical Review B Vol. 109 ( 16 ) page： L161105-1 - L161105-6 2024.4

Electron Localization Induced by Disordered Anions in an Organic Conductor Reviewed

Soichiro Yasaka, Yukihiro Yoshida, Yuki Tanaka, Yuto Nakamura, Hideo Kishida, Hiroshi Kitagawa, and Mitsuhiko Maesato

Inorganic Chemistry Vol. 63 ( 9 ) page： 4196 - 4203 2024.3

Femtosecond depolarization of photoluminescence from InAs: Comparison with Cu and monolayer graphene Reviewed

PHYSICAL REVIEW B Vol. 108 ( 23 ) page： 235103-1 - 235103-9 2023.12

Complex third-order nonlinear susceptibility of single-layer graphene governing third-harmonic generation Reviewed

Daiki Inukai, Takeshi Koyama, Kenji Kawahara, Hiroki Ago, and Hideo Kishida

Physical Review B Vol. 108 ( 7 ) page： 075408-1 - 075408-12 2023.8

Ultrahigh porosity photoluminescent silicon aerocrystals with greater than 50% nanocrystal ensemble quantum yields Reviewed International coauthorship

Gelloz, B; Canham, L; Asaka, K; Nakamura, Y; Kishida, H

JOURNAL OF APPLIED PHYSICS Vol. 134 ( 3 ) page： 033103-1 - 033103-11 2023.7

Particle Size Controlled Chiral Structural Color of Monodisperse Cholesteric Liquid Crystals Particles Reviewed

He Jialei, Liu Sizhe, Gao Guohao, Sakai Miki, Hara Mitsuo, Nakamura Yuto, Kishida Hideo, Seki Takahiro, Takeoka Yukikazu

ADVANCED OPTICAL MATERIALS Vol. 11 ( 19 ) page： 2300296/1 - 2300296/9 2023.10

Fermi energy dependence of ultrafast photoluminescence from graphene Reviewed

Inukai, D; Koyama, T; Araidai, M; Kawahara, K; Ago, H; Kishida, H

JOURNAL OF APPLIED PHYSICS Vol. 132 ( 13 ) page： 134301-1 - 134301-7 2022.10

Electrical-field-induced insulator-to-metal transition in samarium monosulfides Reviewed

K. Kishida, J. Shibutani, T. Hatano, Y. Yokoyama, N. Katayama, Y. Okamoto, Y. Nakamura, H. Kishida, H. S. Suzuki, K. Takehana, Y. Imanaka, and K. Takenaka

Applied Physics Letters Vol. 121 ( 12 ) page： 121901-1 - 121901-6 2022.9

Photoexcited state of the organic electron acceptor TCNQ molecular anion in the condensed state Reviewed

Tomoki Tatsuno, Takeshi Koyama,* and Hideo Kishida

Physical Review B Vol. 106 ( 11 ) page： 115123-1 - 115123-7 2022.9

Light-induced magnetization driven by interorbital charge motion in the spin-orbit assisted Mott insulator α−RuCl₃ Reviewed

T. Amano, Y. Kawakami, H. Itoh, K. Konno, Y. Hasegawa, T. Aoyama, Y. Imai, K. Ohgushi, Y. Takeuchi, Y. Wakabayashi, K. Goto, Y. Nakamura, H. Kishida, K. Yonemitsu, and S. Iwai

Physical Review Research Vol. 4 ( 3 ) page： L032032-1 - L032032-6 2022.8

Photoluminescence of metallic single-walled carbon nanotubes: Role of interband and intraband transitions Reviewed

Takeshi Koyama, Nobuki Umewaki, Kensuke Saito, Tomoki Tatsuno, Akira Fujisaki, Yasumitsu Miyata, Hiromichi Kataura, and Hideo Kishida

Physical Review B Vol. 106 ( 4 ) page： 045421-1 - 045421-8 2022.7

High-pressure polycrystalline thin-film synthesis and semiconducting property of platinum pernitride Reviewed

Ken Niwa, Tomoki Iizuka, Masashi Kurosawa, Yuto Nakamura, Hubert Okadome Valencia, Hideo Kishida, Osamu Nakatsuka, Takuya Sasaki, Nico Alexander Gaida, and Masashi Hasegawa

AIP Advances Vol. 12 ( 5 ) page： 055318-1 - 055318-5 2022.5

Hole Doping in Polythiophenes Encapsulated in Semiconducting and Metallic Single-Walled Carbon Nanotubes: Impact of the Electronic Structure Reviewed

Hiroto Kageyama, Koji Asaka, Hideo Kishida, and Takeshi Koyama

Macromolecules Vol. 54 ( 23 ) page： 11147 - 11153 2021.12

Stabilization of Interfacial Polarization and Induction of Polarization Hysteresis in Organic MISIM Devices Reviewed

ACS APPLIED MATERIALS & INTERFACES Vol. 13 ( 27 ) page： 31928 - 31933 2021.7

Photoluminescence Enhancement Exceeding 10-Fold from Graphene via an Additional Layer: Photoluminescence from Monolayer and Bilayer Graphene Epitaxially Grown on SiC Reviewed

Kensuke Saito, Tomonari Koishi, Jianfeng Bao, Wataru Norimatsu, Michiko Kusunoki, Hideo Kishida, and Takeshi Koyama

The Journal of Physical Chemistry C Vol. 125 ( 20 ) page： 11014 - 11022 2021.5

Femtosecond photoluminescence from monolayer MoS2: Time-domain study on exciton diffusion Reviewed

Saito Kensuke, Okada Mitsuhiro, Kitaura Ryo, Kishida Hideo, Koyama Takeshi

PHYSICAL REVIEW B Vol. 103 ( 20 ) page： L201401-1 - L201401-7 2021.5

Anion Arrangement Effects on Electronic States of κ-type BEDT-TTF Compounds Reviewed

Yuto Nakamura, Naoki Yoneyama, Takahiko Sasaki, Takaaki Hiramatsu, Yukihiro Yoshida, Gunzi Saito, and Hideo Kishida

Journal of the Physical Society of Japan Vol. 90 ( 5 ) page： 054703-1 - 054703-7 2021.5

Phase-transition-induced jumping, bending, and wriggling of single crystal nanofibers of coronene Reviewed International coauthorship

Ken Takazawa, Jun‑ichi Inoue, Kazutaka Mitsuishi, Yukihiro Yoshida, Hideo Kishida, Paul Tinnemans, Hans Engelkamp & Peter C. M. Christianen

Scientific Reports Vol. 11 ( 1 ) page： 3175 2021.2

Electronic States of Electrochemically Doped Single-Layer Graphene Probed through Fano Resonance Effects in Raman Scattering Reviewed

Daiki Inukai, Takeshi Koyama, Kenji Kawahara, Hiroki Ago, and Hideo Kishida

The Journal of Physical Chemistry C Vol. 124 ( 48 ) page： 26428 - 26433 2020.12

Excitation Energy Transfer by Electron Exchange via Two-Step Electron Transfer between a Single-Walled Carbon Nanotube and Encapsulated Magnesium Porphyrin Reviewed

Takeshi Koyama, Junpei Sugiura, Tomonari Koishi, Ryosuke Ohashi, Koji Asaka, Takeshi Saito, Yanlin Gao, Susumu Okada, and Hideo Kishida

The Journal of Physical Chemistry C Vol. 124 ( 35 ) page： 19406 - 19412 2020.9

Petahertz non-linear current in a centrosymmetric organic superconductor Reviewed

Kawakami Y., Amano T., Ohashi H., Itoh H., Nakamura Y., Kishida H., Sasaki T., Kawaguchi G., Yamamoto H. M., Yamamoto K., Ishihara S., Yonemitsu K., Iwai S.

NATURE COMMUNICATIONS Vol. 11 ( 1 ) page： 4138 2020.8

Regular-triangle trimer and charge order preserving the Anderson condition in the pyrochlore structure of CsW₂O₆ Reviewed

Yoshihiko Okamoto, Haruki Amano, Naoyuki Katayama, Hiroshi Sawa, Kenta Niki, Rikuto Mitoka, Hisatomo Harima, Takumi Hasegawa, Norio Ogita, Yu Tanaka, Masashi Takigawa, Yasunori Yokoyama, Kanji Takehana, Yasutaka Imanaka, Yuto Nakamura, Hideo Kishida, Koshi Takenaka

Nature Communications Vol. 11 ( 1 ) page： 3144 2020.6

Canting Antiferromagnetic Spin-Order (T_N = 102 K) in a Monomer Mott Insulator (ET)Ag₄(CN)₅ with a Diamond Spin-Lattice Reviewed

Akihiro Otsuka, Yasuhiro Shimizu, Gunzi Saito, Mitsuhiko Maesato, Andhika Kiswandhi, Takaaki Hiramatsu, Yukihiro Yoshida, Hideki Yamochi, Masahisa Tsuchiizu, Yuto Nakamura, Hideo Kishida, and Hiroshi Ito

Bulletin of the Chemical Society of Japan Vol. 93 ( 2 ) page： 260 - 272 2020.2

Charge Disproportionation and Its Cooling-Rate Dependence in κ-(BEDT-TTF)₂CF₃SO₃ Reviewed

Mizukoshi Kazushi, Ito Hiroshi, Nakamura Yuto, Hayama Hiromi, Yoshida Yukihiro, Saito Gunzi, Kishida Hideo

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Vol. 89 ( 2 ) page： 024710-1 - 024710-11 2020.2

Bis(ethylenedithio)tetrathiafulvalene Cation Radical Salts Composed of Nonuniform Silver(I) Complex Polyanions Reviewed

Yoshida Yukihiro, Maesato Mitsuhiko, Nakamura Yuto, Ishikawa Manabu, Yamochi Hideki, Saito Gunzi, Kishida Hideo, Kitagawa Hiroshi

INORGANIC CHEMISTRY Vol. 58 ( 24 ) page： 16703 - 16711 2019.12

Isolation of Single-Wired Transition-Metal Monochalcogenides by Carbon Nanotubes Reviewed

Masataka Nagata, Shivani Shukla, Yusuke Nakanishi, Zheng Liu, Yung-Chang Lin, Takuma Shiga, Yuto Nakamura, Takeshi Koyama, Hideo Kishida, Tsukasa Inoue, Naoyuki Kanda, Shun Ohno, Yuki Sakagawa, Kazu Suenaga, and Hisanori Shinohara

Nano Letters Vol. 19 ( 8 ) page： 4845 - 4851 2019.8

Partial Substitution of Ag(I) for Cu(I) in Quantum Spin Liquid κ-(ET)₂Cu₂(CN)₃, Where ET Is Bis(ethylenedithio)tetrathiafulvalene Reviewed

Yukihiro Yoshida, Mitsuhiko Maesato, Shinya Tomeno, Yojiro Kimura, Gunzi Saito, Yuto Nakamura, Hideo Kishida, and Hiroshi Kitagawa

Inorganic Chemistry Vol. 58 ( 8 ) page： 4820 - 4827 2019.4

Ultrafast polarization control by terahertz fields via π-electron wavefunction changes in hydrogenbonded molecular ferroelectrics Reviewed

T. Miyamoto, D. Hata, T. Morimoto, H. Yamakawa, N. Kida, T. Terashige, K. Iwano, H. Kishida, S. Horiuchi, H. Okamoto

Scientific Reports Vol. 8 page： 15014 2018.10

Optical Evaluation of Electronic Anisotropy in a Triangular Lattice System κ-(BEDT-TTF)₂B(CN)₄ Reviewed

Kazushi Mizukoshi, Yuto Nakamura, Yukihiro Yoshida, Gunzi Saito, and Hideo Kishida

Journal of the Physical Society of Japan Vol. 87 ( 10 ) page： 104708-1 - 104708-5 2018.10

Acceleration of Photocarrier Relaxation in Graphene Achieved by Epitaxial Growth: Ultrafast Photoluminescence Decay of Monolayer Graphene on SiC Reviewed

Hirotaka Imaeda, Takeshi Koyama, Hideo Kishida, Kenji Kawahara, Hiroki Ago, Ryotaro Sakakibara, Wataru Norimatsu, Tomo-o Terasawa, Jianfeng Bao, and Michiko Kusunoki

The Journal of Physical Chemistry C Vol. 122 ( 33 ) page： 19273 - 19279 2018.8

Nonlinear charge oscillation driven by a single-cycle light field in an organic superconductor Reviewed

Y. Kawakami, T. Amano, Y. Yoneyama, Y. Akamine, H. Itoh, G. Kawaguchi, H. M. Yamamoto, H. Kishida, K. Itoh, T. Sasaki, S. Ishihara, Y. Tanaka, K. Yonemitsu, S. Iwai

Nature Photonics Vol. 12 ( 8 ) page： 474 - 478 2018.8

Charge-transfer complexes based onC_2v-symmetric benzo[ghi]perylene: comparison of their dynamic and electronic properties with those of D_6h-symmetric coronene Reviewed

Yukihiro Yoshida, Shunsuke Tango, Kazuhide Isomura, Yuto Nakamura, Hideo Kishida, Takashi Koretsune, Masafumi Sakata, Yoshiaki Nakano, Hideki Yamochi and Gunzi Saito

Materials Chemistry Frontiers Vol. 2 ( 6 ) page： 1165 - 1174 2018.6

Different Molecular Arrangement of Perylene in Metallic and Semiconducting Carbon Nanotubes: Impact of van der Waals Interaction Reviewed

Takeshi Koyama, Kazuma Fujiki, Yuya Nagasawa, Susumu Okada, Koji Asaka, Yahachi Saito, and Hideo Kishida

The Journal of Physical Chemistry C Vol. 122 ( 10 ) page： 5805 - 5812 2018.3

Modulation of terahertz emission in time-domain waveform via a photoinduced phase transition in a charge ordered organic ferroelectric Reviewed

Hirotake Itoh, Rina Fujiwara, Yohei Kawakami, Kaoru Yamamoto, Yuto Nakamura, Hideo Kishida, and Shinichiro Iwai

Applied Physics Letters Vol. 112 ( 9 ) page： 093302-1 - 093302-5 2018.2

Design and Preparation of a Quantum Spin Liquid Candidate κ-(ET)₂Ag₂(CN)₃ Having a Nearby Superconductivity Reviewed

Takaaki Hiramatsu, Yukihiro Yoshida, Gunzi Saito, Akihiro Otsuka, Hideki Yamochi, Mitsuhiko Maesato, Yasuhiro Shimizu, Hiroshi Ito, Yuto Nakamura, Hideo Kishida, Masashi Watanabe, and Reiji Kumai

Bulletin of the Chemical Society of Japan Vol. 90 ( 9 ) page： 1073 - 1082 2017.9

Racemic charge-transfer complexes of a helical polycyclic aromatic hydrocarbon molecule Reviewed

Yukihiro Yoshida, Yuto Nakamura, Hideo Kishida, Hiromi Hayama, Yoshiaki Nakano, Hideki Yamochi and Gunzi Saito

CrystEngComm Vol. 19 ( 26 ) page： 3626 - 3632 2017.7

Polarization selectivity of charge localization induced by a 7-fs nearly single-cycle light field in an organic metal Reviewed

Y. Kawakami, Y. Yoneyama, T. Amano, H. Itoh, K. Yamamoto, Y. Nakamura, H. Kishida, T. Sasaki, S. Ishihara, Y. Tanaka, K. Yonemitsu, and S. Iwai

Physical Review B Vol. 95 ( 20 ) page： 201105-1 - 201105-5 2017.5

Facile Synthetic Route to Atomically Thin Conductive Wires from Single-Species Molecules in One-Dimensionally Confined Space: Doped Conjugated Polymers inside Single-Walled Carbon Nanotubes Reviewed

Makoto Sasaki, Takeshi Koyama, Hideo Kishida, Koji Asaka, Yahachi Saito, Yukihiro Yoshida, and Gunzi Saito

The Journal of Physical Chemistry Letters Vol. 8 ( 8 ) page： 1702 - 1706 2017.4

Electric-field-induced intradimer charge disproportionation in the dimer-Mott insulator β'-(BEDT-TTF)₂ICl₂ Reviewed

Yuma Hattori, Satoshi Iguchi, Takahiko Sasaki, Shinichiro Iwai, Hiromi Taniguchi, and Hideo Kishida

Physical Review B Vol. 95 ( 8 ) page： 085149-1 - 085149-5 2017.2

Optical Properties of a Quantum Spin Liquid Candidate Material, κ-(BEDT-TTF)₂Ag₂(CN)₃ Reviewed

Yuto Nakamura, Takaaki Hiramatsu, Yukihiro Yoshida, Gunzi Saito, and Hideo Kishida

Journal of the Physical Society of Japan Vol. 86 ( 1 ) page： 014710-1 - 014710-5 2017.1

Hydrogen-surfactant-mediated epitaxy of Ge_1-_xSn_x layer and its effects on crystalline quality and photoluminescence property Reviewed

Osamu Nakatsuka, Shunsuke Fujinami, Takanori Asano, Takeshi Koyama, Masashi Kurosawa, Mitsuo Sakashita, Hideo Kishida, and Shigeaki Zaima

Japanese Journal of Applied Physics Vol. 56 ( 1 ) page： 01AB05-1 – 01AB05-6 2017.1

Terahertz emission from biased conjugated polymers excited by femtosecond laser pulses Reviewed

Takeya Unuma, Naruki Yamada, and Hideo Kishida

Applied Physics Express Vol. 9 ( 12 ) page： 121601-1 - 121601-4 2016.11

BEDT-TTF Salts Formed with Tetrahedrally Coordinated Zinc(II) Complex Anions Reviewed

Yukihiro Yoshida, Hiroshi Ito, Yuto Nakamura, Manabu Ishikawa, Akihiro Otsuka, Hiromi Hayama, Mitsuhiko Maesato, Hideki Yamochi, Hideo Kishida, and Gunzi Saito

Crystal Growth & Design Vol. 16 ( 11 ) page： 6613 - 6630 2016.9

Cationic π-Stacking Columns of Coronene Molecules with Fully Charged and Charge-Disproportionated States Reviewed

Yukihiro Yoshida, Kazuhide Isomura, Mitsuhiko Maesato, Takashi Koretsune, Yoshiaki Nakano, Hideki Yamochi, Hideo Kishida, and Gunzi Saito

Crystal Growth & Design Vol. 16 ( 10 ) page： 5994 - 6000 2016.9

Coronene-based charge-transfer complexes Reviewed

Yukihiro Yoshida, Kazuhide Isomura, Yoshihide Kumagai, Mitsuhiko Maesato, Hideo Kishida, Motohiro Mizuno and Gunzi Saito

Journal of Physics: Condensed Matter Vol. 28 ( 30 ) page： 304001 (14pp) 2016.6

Two-Step Excitation Triggered by One-Photon Absorption on Linear Dispersion in Monolayer Graphene Reviewed

Takeshi Koyama, Kenta Mizutani, Hiroki Ago, and Hideo Kishida

The Journal of Physical Chemistry C Vol. 120 ( 20 ) page： 11225 - 11229 2016.5

Conducting π Columns of Highly Symmetric Coronene, The Smallest Fragment of Graphene Reviewed

Yukihiro Yoshida, Kazuhide Isomura, Hideo Kishida, Yoshihide Kumagai, Motohiro Mizuno, Masafumi Sakata, Takashi Koretsune, Yoshiaki Nakano, Hideki Yamochi, Mitsuhiko Maesato, and Gunzi Saito

Chemistry - A European Journal Vol. 22 ( 17 ) page： 6023 - 6030 2016.4

Segmentation of conducting domains in PEDOT:PSS films induced by an additive for conductivity enhancement Reviewed

Takeya Unuma, Muneki Yoshikawa, Arao Nakamura, and Hideo Kishida

Applied Physics Express Vol. 9 ( 5 ) page： 051601-1 – 051601-4 2016.4

Ultrafast excitation energy transfer from encapsulated quaterrylene to single-walled carbon nanotube Reviewed

Takeshi Koyama, Takuya Tsunekawa, Takeshi Saito, Koji Asaka, Yahachi Saito, Hideo Kishida, Arao Nakamura

Journal of Luminescence Vol. 169 ( part B ) page： 645 - 648 2016.1

Ambient-Pressure Organic Superconductor κ-(ET)₂Ag(CN)[N(CN)₂] Formed with Polymeric Silver(I) Complex Anion Reviewed

Yukihiro Yoshida*, Hiromi Hayama, Manabu Ishikawa, Akihiro Otsuka, Hideki Yamochi, Yuto Nakamura, Hideo Kishida, Hiroshi Ito, Mitsuhiko Maesato, and Gunzi Saito

Journal of the Physical Society of Japan Vol. 84 ( 12 ) page： 123801-1 - 123801-5 2015.12

Improved Dynamic Properties of Charge-Transfer-Type Supramolecular Rotor Composed of Coronene and F₄TCNQ Reviewed

Yukihiro Yoshida, Yoshihide Kumagai, Motohiro Mizuno, Kazuhide Isomura, Yuto Nakamura, Hideo Kishida, and Gunzi Saito

Crystal Growth & Design Vol. 15 ( 11 ) page： 5513–5518 2015.11

Spin frustration in antiperovskite systems: (TTF^·⁺ or TSF^·⁺)₃[(Mo₆X₁₄)^2-Y^-] Reviewed

Takaaki Hiramatsu*, Yukihiro Yoshida, Gunzi Saito*, Akihiro Otsuka, Hideki Yamochi, Yasuhiro Shimizu, Yuma Hattori, Yuto Nakamura, Hideo Kishida, Hiroshi Ito, Kaplan Kirakci, Stéphane Cordier and Christiane Perrin

Journal of Materials Chemistry C Vol. 3 ( 42 ) page： 11046 - 11054 2015.11

Photoluminescence of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) in the visible region Reviewed

Takeshi Koyama, Taiki Matsuno, Yasunori Yokoyama and Hideo Kishida

Journal of Materials Chemistry C Vol. 3 ( 32 ) page： 8307 - 8310 2015.8

Spin-disordered quantum phases in a quasi-one-dimensional triangular lattice Reviewed

Yukihiro Yoshida, Hiroshi Ito, Mitsuhiko Maesato, Yasuhiro Shimizu, Hiromi Hayama, Takaaki Hiramatsu, Yuto Nakamura, Hideo Kishida, Takashi Koretsune, Chisa Hotta, and Gunzi Saito

Nature Physics Vol. 11 ( 8 ) page： 679 - 683 2015.6

Charge-transfer Complex Formed with Bowl-shaped Corannulene as Electron Donor and Planar 7,7,8,8-Tetracyanoquinodimethane as Electron Acceptor Reviewed

Yukihiro Yoshida, Kazuhide Isomura, Yuto Nakamura, Hideo Kishida, and Gunzi Saito

Chemistry Letters Vol. 44 ( 5 ) page： 709 - 711 2015.5

Study of Magnetic Excitation in Pd(dmit)₂ Salts by Raman Scattering Spectroscopy Reviewed

Yuto Nakamura, Reizo Kato, and Hideo Kishida

Journal of the Physical Society of Japan Vol. 84 ( 4 ) page： 044715-1 - 044715-5 2015.4

Quantum spin liquid: design of a quantum spin liquid next to a superconducting state based on a dimer-type ET Mott insulator Reviewed

Takaaki Hiramatsu, Yukihiro Yoshida, Gunzi Saito, Akihiro Otsuka, Hideki Yamochi, Mitsuhiko Maesato, Yasuhiro Shimizu, Hiroshi Ito and Hideo Kishida

Journal of Materials Chemistry C Vol. 3 ( 6 ) page： 1378 - 1388 2015.2

Optical freezing of charge motion in an organic conductor Reviewed

Takahiro Ishikawa, Yuto Sagae, Yota Naitoh, Yohei Kawakami, Hirotake Itoh, Kaoru Yamamoto, Kyuya Yakushi, Hideo Kishida, Takahiko Sasaki, Sumio Ishihara, Yasuhiro Tanaka, Kenji Yonemitsu, and Shinichiro Iwai

Nature Communications Vol. 5 page： 5528 (6 pages) 2014.11

Synthesis and Photophysics of Quaterrylene Molecules in Single-Walled Carbon Nanotubes: Excitation Energy Transfer between a Nanoscale Cylinder and Encapsulated Molecules Reviewed

Takeshi Koyama, Takuya Tsunekawa, Takeshi Saito, Koji Asaka, Yahachi Saito, Hideo Kishida, and Arao Nakamura

The Journal of Physical Chemistry C Vol. 118 ( 37 ) page： 21671 - 21681 2014.9

Isotropic Three-Dimensional Molecular Conductor Based on the Coronene Radical Cation Reviewed

Yukihiro Yoshida,, Mitsuhiko Maesato, Yoshihide Kumagai, Motohiro Mizuno, Kazuhide Isomura, Hideo Kishida, Masanari Izumi, Yoshihiro Kubozono, Akihiro Otsuka, Hideki Yamochi, Gunzi Saito, Kaplan Kirakci, Stéphane Cordier and Christiane Perrin

European Journal of Inorganic Chemistry Vol. 2014 ( 24 ) page： 3871 - 3878 2014.3

Microscopic Mobility of Polarons in Chemically Doped Polythiophenes Measured by Employing Photoluminescence Spectroscopy Reviewed

Takeshi Koyama, Arao Nakamura , and Hideo Kishida

ACS Photonics Vol. 1 ( 8 ) page： 655 - 661 2014.7

Magnetic Raman Scattering Study of Spin Frustrated Systems, κ-(BEDT-TTF)₂X Reviewed

Yuto Nakamura, Naoki Yoneyama, Takahiko Sasaki, Takami Tohyama, Arao Nakamura, Hideo Kishida

J. Phys. Soc. Jpn. Vol. 83 ( 7 ) page： 074708-1 - 074708-5 2014.6

Third-Order Nonlinear Optical Properties and Electroabsorption Spectra of an Organic Biradical, [Naphtho[2,1-d:6,5-d']bis([1,2,3]dithiazole)] Reviewed

Keigo Takauji, Rie Suizu, Kunio Awaga, Hideo Kishida, and Arao Nakamura

The Journal of Physical Chemistry C Vol. 118 ( 8 ) page： 4303 - 4308 2014.2

Electron-Transfer Processes in Highly-Correlated Electron Systems of Thiazyl Radicals Reviewed

Kunio Awaga, Kenji Nomura, Hideo Kishida, Wataru Fujita, Hirofumi Yoshikawa, Michio M. Matsushita, Laigui Hu, Yoshiaki Shuku, and Rie Suizu

Bulletin of the Chemical Society of Japan Vol. 87 ( 2 ) page： 234 - 249 2014.2

Anisotropic terahertz complex conductivities in oriented polythiophene films Reviewed

Takeya Unuma*, Atsuhiro Umemoto, and Hideo Kishida

Applied Physics Letters Vol. 103 ( 21 ) page： 213305-1 - 213305-4 2013.11

Measurement of the Nonlinear Conducting States of α-(BEDT-TTF)₂I₃ Using Electronic Raman Scattering Reviewed

Atsuya Ito, Yuto Nakamura, Arao Nakamura, and Hideo Kishida

Physical Review Letters Vol. 111 ( 19 ) page： 197801-01 - 197801-05 2013.11

Transient Absorption Kinetics Associated with Higher Exciton States in Semiconducting Single-Walled Carbon Nanotubes: Relaxation of Excitons and Phonons Reviewed

Takeshi Koyama, Shohei Yoshimitsu, Yasumitsu Miyata, Hisanori Shinohara, Hideo Kishida, and Arao Nakamura

The Journal of Physical Chemistry C Vol. 117 ( 39 ) page： 20289 - 20299 2013.9

Narrowing of phonon spectrum induced by ultrafast charge fluctuations in an organic dimer Mott insulator Reviewed

K. Itoh, H. Itoh, S. Saito, I. Hosako, Y. Nakamura, H. Kishida, N. Yoneyama, T. Sasaki, S. Ishihara, and S. Iwai

Physical Review B Vol. 88 ( 12 ) page： 125101-1 - 125101-6 2013.9

Direct observation of carrier delocalization in highly conducting polyaniline Reviewed

Takeya Unuma, Naruki Yamada, Arao Nakamura, Hideo Kishida, Seung-Chul Lee, Eun-Young Hong, Suck-Hyun Lee, and O-Pil Kwon

Applied Physics Letters Vol. 103 ( 5 ) page： 053303-1 - 053303-4 2013.8

Dispersion relations for evaluating the complex refractive index of medium without the information of its thickness Reviewed

Kai-Erik Peiponen, Erik M. Vartiainen, Takeya Unuma, J. Axel Zeitler, Pertti Silfsten, Tapani Venäläinen, and Hideo Kishida

Applied Physics Letters Vol. 102 ( 18 ) page： 181110-1 - 181110-5 2013.5

Near-Infrared Photoluminescence in the Femtosecond Time Region in Monolayer Graphene on SiO₂ Reviewed

Takeshi Koyama, Yoshito Ito, Kazuma Yoshida, Masaharu Tsuji, Hiroki Ago, Hideo Kishida, and Arao Nakamura

ACS Nano Vol. 7 ( 3 ) page： 2335–2343 2013.3

Photophysics in Single-Walled Carbon Nanotubes with (6,4) Chirality at High Excitation Densities: Bimolecular Auger Recombination and Phase-Space Filling of Excitons Reviewed

Takeshi Koyama, Yasumitsu Miyata, Hideo Kishida, Hisanori Shinohara, and Arao Nakamura

The Journal of Physical Chemistry C Vol. 117 ( 4 ) page： 1974–1981 2013.1

Development of a Robust Model System of FRET using Base Surrogates Tethering Fluorophores for Strict Control of Their Position and Orientation within DNA Duplex Reviewed

Tomohiro Kato, Hiromu Kashida*, Hideo Kishida, Hiroyuki Yada, Hiroshi Okamoto, and Hiroyuki Asanuma*

Journal of the American Chemical Society Vol. 135 ( 5 ) page： 741–750 2012.12

Quadrimolecular Recombination of Persistent Photocarriers in Surface-Type Photocells of Regioregular Poly(3-hexylthiophene)/Methanofullerene Composites Reviewed

Hiroshi Ito*, Yuki Nishikawa, Junya Suzuki, Akimitsu Suzuki, Shun-ichiro Watanabe, Hisaaki Tanaka, Hideo Kishida, Arao Nakamura, and Shin-ichi Kuroda

Japanese Journal of Applied Physics Vol. 50 page： 091602-1 - 091602-4 2011.9

Room-temperature current oscillation based on negative differential resistance in a one-dimensional organic charge-transfer complex Reviewed

Hideo Kishida, Takafumi Ito, Atsuya Ito, and Arao Nakamura

Applied Physics Express Vol. 4 page： 031601-1 - 031601-3 2011.3

Femtosecond luminescence decay due to exciton energy transfer in single-walled carbon nanotube bundles Reviewed

Takeshi Koyama, Koji Asaka, Naoki Hikosaka, Hideo Kishida, Yahachi Saito, Arao Nakamura

Journal of Luminescence Vol. 131 ( 3 ) page： 494 - 497 2011.3

Ultrafast exciton energy transfer in bundles of single-walled carbon nanotubes Reviewed

Takeshi Koyama, Koji Asaka, Naoki Hikosaka, Hideo Kishida, Yahachi Saito, and Arao Nakamura

The Journal of Physical Chemistry Letters Vol. 2 ( 3 ) page： 127 - 132 2011.1

Multiply-resonant nonlinear optical processes in doped polythiophenes Reviewed

Hideo Kishida, Kenichi Hibino, and Arao Nakamura

Applied Physics Letters Vol. 97 ( 10 ) page： 103302-1 - 103302-3 2010.9

Third-Order nonlinear optical properties of a π-Conjugated biradical molecule investigated by third-harmonic generation spectroscopy Reviewed

Hideo Kishida, Kenichi Hibino, Arao Nakamura, Daisuke Kato, Jiro Abe

Thin Solid Films Vol. 519 page： 1028 - 1030 2010.8

Terahertz complex conductivities of carriers with partial localization in doped polythiophenes Reviewed

Takeya Unuma, Kenji Fujii, Hideo Kishida, and Arao Nakamura

Applied Physics Letters Vol. 97 ( 3 ) page： 033308-1 - 033308-3 2010.7

Optoelectronic conversion by polarization current, triggered by spacecharges at organic-based interfaces Reviewed

Laigui Hu, Yukiko Noda, Hiroshi Ito, Hideo Kishida, Arao Nakamura, and Kunio Awaga

Applied Physics Letters Vol. 96 ( 24 ) page： 243303-1 - 243303-3 2010.6

Ferroelectric nature and real-space observations of domain motions in the organic charge-transfer compound tetrathiafulvalene-p-chloranil Reviewed

Hideo Kishida, Hisashi Takamatsu, Ken Fujinuma, and Hiroshi Okamoto

Physical Review B Vol. 80 ( 20 ) page： 205201-1 - 205201-7 2009.11

π-Conjugated Multi-Donor/Acceptor Arrays of Fullerene–Cobaltadithiolene–Tetrathiafulvalene: From Synthesis and Structure to Electronic Interactions Reviewed

Yutaka Matsuo, Masashi Maruyama, S. Shankara Gayathri, Tomoya Uchida, Dirk M. Guldi,Hideo Kishida, Arao Nakamura, and Eiichi Nakamura

Journal of the American Chemical Society Vol. 131 ( 35 ) page： 12643 - 12649 2009.8

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

The synthesis, structure, photoelectrochemical behavior, and nonlinear optical (NLO) properties
of a symmetric acceptor-acceptor-donor-acceptor-acceptor array, C60-Co-TTF-Co-C60, have been
described. The precursors, namely, cobalt dicarbonyl complexes Co(C60Ar5)(CO)2 were synthesized from
the penta(organo)[60]fullerenes, C60Ar5H, as starting materials. In the next step, two cobalt-fullerene
complexes were connected to a tetrathiafulvalene (TTF) tetrathiolate bridge to obtain the C60-Co-TTF-Co-
C60 array. In addition, the monomeric compounds, Co(C60Ar5)(S2C2R2) (R ) CO2Me and CN) and
Co(C60Ar5)(S2C2S2 C ) CS2C2R2) were synthesized as references. The C60-Co-TTF-Co-C60 array exhibits
very strong transitions in the near-infrared region (λmax ) 1,100 nm, ε ) 30 000 M-1 ·cm-1) due to a ligandto-
metal-charge-transfer (LMCT) transition and six reversible electron transfer processes. In the crystal, a
fullerene/TTF-layered packing structure is evident. Femtosecond flash photolysis revealed that photoexcitation
of the array results in a charge separated state involving the strongly interacting cobaltadithiolene
and TTF constituents which electronically relax via a resonance effect that extends all throughout the
acceptor parts of the C60-Co-TTF-Co-C60 array. The third-order NLO measurement of the array gave the
magnitude of the third-order nonlinear susceptibility, |(3)|, values to be 9.28 × 10-12 esu, suggesting
the π-conjugation of donors and acceptors in the array.

DOI： 10.1021/ja902312q

Highly Coplanar Polythiophenes with -C≡CR Side Chains:Self-assembly, Linear and Nonlinear Optical Properties, and Piezochromism Reviewed

Takakazu Yamamoto, Takao Sato, Takayuki Iijima, Masahiro Abe, HirokiFukumoto, Take-aki Koizumi, Motoaki Usui, Yoshiyuki Nakamura, TakehikoYagi, Hiroyuki Tajima, Taku Okada, Shintaro Sasaki, Hideo Kishida, AraoNakamura, Takashi Fukuda, Akira Emoto, Hirobumi Ushijima, ChisatoKurosaki, and Hiroshi Hirota

Bulletin of the Chemical Society of Japan Vol. 82 ( 7 ) page： 896 - 909 2009.7

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

Self-assembly of polythiophenes with C≡CR (R = alkyl, phenyl, etc.) side chains has been investigated. Seven
new polymers consisting of head-to-head and tail-to-tail 2,2¤-bithiophenes with C≡CR side chains were synthesized. The new polymers include alternating copolymers between bithiophenes with C≡C alkyl side chains and thiophene and those between bithiophenes with C≡C alkyl side chains and 2,2¤-bithiophene. The polythiophene main chain is considered to be coplanar because of the absence of steric repulsion between the main chain and the C≡CR side chain. Single-crystal X-ray crystallography and DFT calculations indicated that the head-to-head- and tail-to tail-2,2-bithiophenes with C≡CR side chains were coplanar. The polythiophenes with C≡CR side chains showed a strong tendency to selfassemble, and assumed edge-on alignment and side-on alignment on the surface of substrates. Self-assembly caused a decrease in the pi-pi* transition energy of the polymers by 0.3 0.4eV. A copolymer of thiophene and dialkoxy-pphenylene showed analogous self-assembly. The polythiophenes with C≡CR side chains showed piezochromism, with a decrease in the pi-pi* transition energy by about 0.2 eV at 10 GPa. Head-to-head-P3(C≡CDec) Th with a C≡C decyl side chain gave a larger optical third-order nonlinear susceptibility chi(3) than regio-regular poly(3-hexylthiophene)s.

DOI： 10.1246/bcsj.82.896

Current oscillation originating from negative differential resistancein one-dimensional halogen-bridged nickel compounds Reviewed

Hideo Kishida, Takafumi Ito, Arao Nakamura, Shinya Takaishi, and MasahiroYamashita

Journal of Applied Physics Vol. 106 ( 1 ) page： 016106-1 - 016103-3 2009.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We demonstrate current oscillation phenomena using the negative differential resistance
in a one-dimensional halogen-bridged nickel compound, [Ni(chxn)2Br]Br2 (chxn
=cyclohexanediamine). By attaching external resistors and a capacitor to a [Ni(chxn)2Br]Br2
sample, we obtain stable current oscillation at 90 K. The oscillation and its period are explained by
a simple model.

DOI： 10.1063/1.3157211

Effect of an In-Plane Ligand on the Electronic Structures of Bromo-Bridged Nano-Wire Ni-Pd Mixed-Metal Complexes, [Ni_1-xPd_x(bn)₂Br]Br₂ (bn = 2S,3S-Diaminobutane) Reviewed

Mari Sasaki, Hashen Wu, Daisuke Kawakami, Shinya Takaishi, Takashi Kajiwara, Hitoshi Miyasaka,Brian K. Breedlove, Masahiro Yamashita, Hideo Kishida, Hiroyuki Matsuzaki, Hiroshi Okamoto,Hisaaki Tanaka, and Shinichi Kuroda

Inorganic Chemistry Vol. 48 ( 15 ) page： 7446 - 7451 2009.7

Third-order nonlinear optical response in double-walled carbon nanotubes Reviewed

A. Nakamura, N. Hikosaka, S. Imamura, Y. Takahashi, H. Ago, and H. Kishida

Journal of Luminescence Vol. 129 ( 12 ) page： 1722 - 1725 2009.12

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

Resonant behavior and magnitudes of third-order nonlinear optical susceptibilities in double-walled carbon nanotubes (DWNTs) have been investigated by means of femtosecond pump-probe spectroscopy with different pump-photon energies. With the selective excitation of the E22 exciton transition of the inner tubes labeled by the chiral vector indices (7,5) and (7,6), the imaginary part of nonlinear susceptibility Imχ(3) has shown the resonant enhancement compared with the case of the nonresonant excitation of the specific tube. The nonlinear response signal at the E22 transition energy of the (8,7) tube has been also enhanced for the excitation of the G-band phonon sideband of its E22 transition. This result is consistent with the phonon-mediated nonlinear optical process observed for the E22 transitions in single-walled carbon nanotubes (SWNTs). It has been also found that the values of the figure of merit Im χ(3)/α (α: absorption coefficient) of the inner tubes in DWNTs are smaller than those of the corresponding SWNTs, which is interpreted in terms of decay time shortening due to the energy relaxation between the inner and outer tubes.

DOI： 10.1016/j.jlumin.2009.02.027

A black body absorber from vertically aligned single-walled carbon nanotubes Reviewed

K. Mizuno, J. Ishii, H. Kishida, Y. hayamizu, S. yasuda, D. N. Futaba, M. Yumura, and K. Hata

Proceedings of the national academy of sciences of the United States of America Vol. 106 page： 6044 - 6047 2009.4

Two-photon excited states in charge-transfer type conjugated polymers Reviewed

Hideo Kishida, Keisuke Hirota, Hiroshi Okamoto, Hisashi Kokubo, Takakazu Yamamoto

Synthetic Metals Vol. 159 ( 9-10 ) page： 868 - 870 2009.5

Resonant enhancement of third-order optical nonlinearities in single-walled carbon nanobutes Reviewed

Y. Takahashi, S. Imamura, H. Kishida, A. Nakamura

Journal of Luminescence Vol. 128 page： 1019 - 1021 2008.5

Direct observation of dark excitons in micelle-wrapped single-wall carbon nanotubes Reviewed

Hideo Kishida,Yoshiaki Nagasawa, Sadanobu Imamura, Arao Nakamura

Physical Review Letters Vol. 100 ( 9 ) page： 097401-1 - 097401-4 2008.3

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have performed electroabsorption spectroscopy on micelle-wrapped single-wall carbon nanotubes.
In semiconducting nanotubes, many oscillating structures composed of the increase and decrease of
absorption are observed in the spectra in the region of the first and second absorption bands, E11 and E22.
The spectral shape is reproduced mainly by the second-derivative curve of the absorption spectrum, which
indicates the presence of nearly degenerate bright and dark excitonic states.

DOI： 10.1103/PhysRevLett.100.097401

Continuous control of third-order optical nonlinearity in charge-transfer-typeconjugated polymers Reviewed

H. Kishida, K. Hirota, H. Okamoto, H. Kokubo, and T. Yamamoto

Applied Physics Letters Vol. 92 ( 3 ) page： 033309-1 - 033309-3 2008.1

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Third-order optical nonlinearity was investigated in two charge-transfer CT-type conjugated polymers, polyaryleneethynyleneand polythiophene-alt-thiazole, using the third-harmonic
generation THG method. Comparison of the results with previously obtained THG data for
polythiophene and the strong CT polymer polythiophene-alt-quinoxaline revealed that the ratio of
the maximum value of third-order nonlinear susceptibility and the absorption coefficient
max chi(3)/alpha max increased as the degree of CT character increased for the four polymers. This
variation in max chi(3)/alpha max is discussed based on the magnitude of the transition dipole moment
between the one-photon-allowed and the one-photon-forbidden excited states.

DOI： 10.1063/1.2837643

Thermochromism in an organic crystal based on the coexistence of σ- and π-dimers Reviewed

Y. Morita, S. Suzuki, K. Fukui, S. Nakazawa, H. Kitagawa, H. Kishida, H. Okamoto, A. Naito, A. Sekine, Y. Ohashi, M. Shiro, K. Sasaki, D. Shiomi, K. Sato, T. Takui & K. Nakasuji

Nature Materials Vol. 7 page： 48 - 51 2007.12

Ultrafast photoinduced melting of spin-Peierls phase in the organic charge-transfer compounds alkali-tetracyanoquinodimethane Reviewed

K. Ikegami, K. Ono, J. Togo, T. Wakabayashi, Y. Ishige, H. Matsuzaki, H. Kishida, H. Okamoto

Physical Review B Vol. 76 ( 8 ) page： 085106-1 - 085106-12 2007.8

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

Photoinduced phase transitions in spin-Peierls SP systems of alkali M=K,Na-tetracyanoquinodimethane
TCNQ have been studied by a reflection-type femtosecond fs pump-probe spectroscopy. The SP phase is
destabilized by the generation of photocarriers through the breaking of the spin-singlet states in dimers. It
results in the decrease of the dimeric molecular displacements within a few hundred of femtoseconds over
several tens of TCNQ molecules. It is accompanied by the displacive-type coherent oscillations, which consist
mainly of three modes with the frequencies of 20, 49, and 90 cm-1 in K-TCNQ and of two modes with the
frequencies of 49 and 99 cm-1 in Na-TCNQ. By taking into account the temperature dependence of the Raman
scattering spectra, the mode with 20 cm-1 in K-TCNQ and the modes with 49 and 99 cm-1 in Na-TCNQ are
assigned to the phonon modes in the SP ground state, while the modes with 49 and 90 cm-1 in K-TCNQ are
assigned to the local modes originating from the photoexcited states. Polarization dependence of the Raman
scattering signals shows that the 20-cm-1 mode of K-TCNQ and the 49-cm-1 mode of Na-TCNQ are longitudinal
optical LO modes, whereas the 99-cm-1 mode of Na-TCNQ is a transverse optical TO mode.
Namely, the LO mode plays an important role on the stabilization of the SP phase in K-TCNQ, while both the
LO and TO modes in Na-TCNQ. Such a difference is discussed by scrutinizing the difference of the crystal
structures and the nature of the SP transitions in the two compounds.

DOI： 10.1103/PhysRevB.76.085106

Strong stacking behavior and large third-order nonlinear optical susceptibility χ⁽³⁾ of head-to-head-type poly(3-alkynylthiophene-2,5-diyl), HH-P3(C≡CR)Th Reviewed

T. Sato, H. Kishida, A. Nakamura, T. Fukuda, T. Yamamoto

Synthetic Metals Vol. 157 ( 6-7 ) page： 318 - 322 2007.5

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

The head-to-head-type poly(3-alkynylthiophene-2,5-diyl) HH-P3(Ctriple bond; length of mdashCR)Th has been shown to exhibit a strong tendency to self-assemble. The UV–vis spectrum of HH-P3(Ctriple bond; length of mdashCDec)Th (Dec = decyl) in 1,2-dichlorobenzene at 131 °C showed a peak at λmax = 520 nm, which shifted to λmax = 553 nm at 25 °C, with a shoulder peak at 608 nm. However, the UV–vis spectrum of an HH-P3(Ctriple bond; length of mdashCDec)Th film showed a more pronounced shift in its UV–vis absorption peak to a longer wavelength. These phenomena are the characteristics of the self-assembly of the polymer molecule. The HH-P3(Ctriple bond; length of mdashCDec)Th film had a large third-order nonlinear optical susceptibility χ(3) of 3.6 × 10-11 esu.

DOI： 10.1016/j.synthmet.2007.04.002

Tuning of Electronic Structures of Quasi-One-Dimensional Bromo-Bridged Pd^Ⅱ-Pd^Ⅳ Mixed-Valence Complexes by Substituting Counter Anions Reviewed

H. Arakawa, D. Kawakami, S. Takaishi, T. Kajiwara, H. Miyasaka, K. Sugiura, M. Yamashita, H. Kishida, H. Okamoto,

Bulletin of the Chemical Society of Japan Vol. 80 ( 1 ) page： 189 - 191 2007.1

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

New quasi-one-dimensional bromo-bridged PdII–PdIV
mixed-valence complexes with long chain alkylsufonates
[Pd(en)2][PdBr2(en)](CnH2nþ1SO3)4-2H2O (en = ethylenediamine, n = 7, 8, 9, and 10) were synthesized. With increasing alkyl-chain length (n) of the counter anions, the PdII ... PdIV distances decreased, indicating that the oxidation states of the Pd atoms are close to the PdIII state.

DOI： 10.1246/bcsj.80.189

Versatile vapochromic behavior accompanied by a phase change between charge-polarization state and charge-density-wave state in a quasi-one-dimensional iodo-bridged dinuclear platinum mixed-valence compound, [{NH₃(CH₂)₅ NH₃}₂]-[Pt₂(pop)₄I]・4H₂O Reviewed

M. Yamashita, K. Takizawa, S. Matsunaga, D. Kawakami, H. Iguchi, S. Takaishi, T. Kajiwara, F. Iwahori, T. Ishii, H. Miyasaka, K. Sugiura, H. Matsuzaki, H. Kishida, H. Okamoto

Bulletin of the Chemical Society of Japan Vol. 79 ( 9 ) page： 1404 - 1406 2006.9

Sr₂TMO₃ (TM = Ni, Co) Compounds with 1D TM-O Chains Invited Reviewed

M. Ohtani, H. Kishida, K. Hirota, H. Sakurada, N. Kawamoto, Y. Murakami, K. Ueno, J. Matsuno, Y. Okimoto, T. Makino, Y. Segawa, Y. Tokura, D. Shindo, H. Okamoto, M. Kawasaki

Advanced Materials Vol. 18 ( 19 ) page： 2541 - 2544 2006.9

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

Sr2TMO3 (TM = Ni,Co) compounds with 1D TM-O chains have been successfully synthesized in the form of single-crystalline thin films using a combinatorial approach. The crystal structure is examined using X-ray diffraction and high-resolution TEM (see figure). Polarized absorption spectroscopy and third-harmonic generation spectroscopy reveal a 1D electronic structure and sizable nonlinear optical susceptibility, respectively, for Sr2NiO3.

DOI： 10.1002/adma.200501759

Dynamical Valence Fluctuation at the Charge-Density-Wave Phase Boundary in Iodide-Bridged Pt Compound [Pt(chxn)₂I]I₂ Reviewed

S. Takaishi, D. Kawakami, M. Yamashita, M. Sasaki, T. Kajiwara, H. Miyasaka, K. Sugiura, Y. Wakabayashi, H. Sawa, H. Matsuzaki, H. Kishida, H. Okamoto, H. Watanabe, H. Tanaka, K. Marumoto, H. Ito, S. Kuroda

Journal of American Chemical Society Vol. 128 page： 6420 - 6425 2006.4

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

We synthesized a novel iodo-bridged linear chain platinum compound, having the quasi-twodimensional
charge-density-wave (CDW) ground state and the smallest band gap. In this compound, we discovered an anomalous valence state in the boundary region at which the CDW phase alternates in the crystal by means of ESR, X-ray diffuse scattering, STM, and electrical resistivity. This anomalous state can be explained by the fast fluctuation between PtIV-I...PtII and PtII...I-PtIV in the double well potential. This is the first observation of the dynamical fluctuation of the CDW phase among the quasi one-dimensional halogen-bridged complexes.

DOI： 10.1021/ja060193b

Gigantic Optical Stark Effect and Ultrafast Relaxation of Excitons in Single-Walled Carbon Nanotubes Reviewed

A. Maeda, S. Matsumoto, H. Kishida, T. Takenobu, Y. Iwasa, H. Shimoda, O. Zhou, M. Shiraishi, H. Okamoto

Journal of the Physical Society of Japan Vol. 75 ( 4 ) page： 043709-1 - 043709-4 2006.4

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

We report a splitting and a shift of exciton absorptions in semiconducting single-walled carbon
nanotubes (SWNTs) by resonant and off-resonant excitation using a fs laser pulse, respectively. This is
the first unambiguous observation of the optical Stark effect of excitons in SWNTs, which is responsible
for their high optical-switching performance. By scrutinizing transient absorption spectra from the midto
near-infrared region (0.1– 0.8 eV), the ultrafast recovery of real carrier excitations characteristic of
bundled structures was attributed to the energy- and charge-transfer processes to metallic SWNTs.

DOI： 10.1143/JPSJ.75.043709

Ultrafast Photoinduced Melting of a Spin-Peierls Phase in an Organic Charge-Transfer Compound, K-Tetracyanoquinodimethane Reviewed

H. Okamoto, K. Ikegami, T. Wakabayashi, Y. Ishige, J. Togo, H. Kishida, H. Matsuzaki

Physical Review Letters Vol. 96 page： 037405-1 - 037405-4 2006.1

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

Ultrafast photoinduced phase transition in a spin-Peierls (SP) system of K-tetracyanoquinodimethane
(K-TCNQ) was studied by femtosecond (fs) reflection spectroscopy. Photocarriers destabilize the SP
phase, resulting in a decrease in molecular dimerization within 400 fs. Such a melting of the SP phase
drives three kinds of coherent oscillations. By comparing the oscillations with the Raman bands activated
by the dimerization, we show that the oscillation of 20 cm1 is due to an LO phonon, and it plays an
important role for the stabilization of the SP phase.

DOI： 10.1103/PhysRevLett.96.037405

Valence Fluctuation and Domain-Wall Dynamics in Pressure-Induced Neutral-to-Ionic Phase Transition of Organic Charge-Transfer Crystal Reviewed

H. Matsuzaki1, H. Takamatsu, H. Kishida and H. Okamoto

Journal of the Physical Society of Japan Vol. 74 ( 11 ) page： 2925 - 2928 2005.11

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

A pressure-induced neutral-to-ionic (N–I) transition in tetrathiafulvalene-p-chroranil was studied by
infrared vibration spectra. With increasing pressure, two CO stretching bands probing coexisting N and I
states merge due to rapid valence fluctuations. From the spectral analyses with the exchange-narrowing
model, we derive the pressure dependence of the N–I exchange rate related to the N–I domain-wall
motions, which explains the anomalous increase in conductivity under pressure. We also demonstrate a
para- to ferro-electric transition at 1.5 GPa as well as the N–I transition at 0.95 GPa.

DOI： 10.1143/JPSJ.74.2925

Two-step spin conversion in a cyanide-bridged ferrous square Reviewed

M. Nihei, M. Ui, M. Yokota, L. Han, A. Maeda, H. Kishida, H. Okamoto, H. Oshio

Angewandte Chemie International Edition Vol. 44 ( 40 ) page： 6484 - 6487 2005.10

Nonlinear and ultrafast optical response in single-walled carbon nanotubes Reviewed

A. Maeda, S. Matsumoto, H. Kishida, T. Takenobu, Y. Iwasa, M. Shiraishi, M. Ata, H. Okamoto

Journal of Physics: Conference Series Vol. 21 page： 177 - 182 2005.5

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

We measured third-order nonlinear susceptibility (􀀂(3)) spectra in semiconducting single-walled carbon nanotubes (SWNTs) by the 􀀂-scan method. |Im􀀂(3)| is remarkably
enhanced under resonant excitation to the lowest interband transition, reaching 4.2 􀀂 10􀀂6 esu.
A comparison of the transient absorption changes evaluated by degenerate and nondegenerate pump-probe measurements suggests that the resonant enhancement of |Im􀀂(3)| is dominated by a coherent process rather than by incoherent one such as saturation of absorption.

DOI： 10.1088/1742-6596/21/1/029

Third-order optical nonlinearity in regio-controlled polythiophene films Reviewed

H. Kishida, K. Hirota, T. Wakabayashi, H. Okamoto, H. Kokubo, T. Yamamoto

Applied Physics Letters Vol. 87 page： 121902-1 – 121902-3 2005.9

Third-order nonlinear optical spectroscopy in charge-transfer-type conjugated polymers Reviewed

H. Kishida, K. Hirota, T. Wakabayashi, H. Okamoto, B. L. Lee, H. Kokubo, T. Yamamoto

Synthetic Metals Vol. 153 ( 1-3 ) page： 141 - 144 2005.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have investigated the linear and third-order nonlinear optical properties in a charge-transfer (CT) type conjugated copolymer, PThQx, which is composed of an electron-donating molecule, thiophene (Th), and electron-accepting one, quinoxaline (Qx), by using the linear absorption, two-photon absorption (TPA), and third-harmonic generation (THG) spectroscopies. In comparison with a homopolymer, polythiophene, the absorption coefficient α of PThQx is significantly reduced, while its third-order nonlinear susceptibility (χ(3)) is unchanged. This indicates that the figure of merit for the nonlinear optical materials, defined as χ(3)/α, is enhanced in PThQx. This enhancement comes from the CT character of the excited states in PThQx, in which a hole and an electron are created on different molecules.

DOI： 10.1016/j.synthmet.2005.07.147

Direct observation of excitons and a continuum of one-dimensional Mott insulators: A reflection-type third-harmonic-generation study of Ni-halogen chain compounds Reviewed

M. Ono, H. Kishida, H. Okamoto

Physical Review Letters Vol. 95 page： 087401-1 - 087401-4 2005.8

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

The third-harmonic-generation (THG) spectrum was measured for a NiBr-chain compound, which is a
one-dimensional Mott insulator, in a reflection configuration. A sharp peak and a shoulder structure in the
THG spectrum are attributed to three-photon resonance to an exciton and a continuum, respectively. The
band-edge energy, the exciton binding energy, and the spectral weights for the exciton and the continuum
were determined from comparative studies of linear absorption, THG, and electroreflectance spectra. The
excitonic effect is more pronounced in the NiCl chain than in the NiBr chain.

DOI： 10.1103/PhysRevLett.95.087401

Real-space observation of ferroelectric domains in organic charge-transfer complexes by electromodulation method Reviewed

H. Kishida, K. Fujinuma, H. Takamatsu, H. Okamoto

Transaction of the Materials Research Society of Japan Vol. 30 ( 1 ) page： 75-78 2005.3

Vapochromic Behavior Accompanied by Phase Transition between Charge-Polarization and Charge-Density-Wave States in a Quasi-One-Dimensional Iodine-Bridged Dinuclear Platinum Compound Reviewed

H. Matsuzaki, H. Kishida, H. Okamoto, K. Takizawa, S. Matsunaga, S. Takaishi, H. Miyasaka, K. Sugiura, M. Yamashita

Angewandte Chemie International Edition Vol. 44 ( 21 ) page： 3240 - 3243 2005.5

Large Optical Nonlinearity of Semiconducting Single-Walled Carbon Nanotubes under Resonant Excitations Reviewed

A. Maeda, S. Matsumoto, H. Kishida, T. Takenobu, Y. Iwasa, M. Shiraishi, M. Ata, and H. Okamoto

Physical Review Letters Vol. 94 page： 047404-1 － 047404-4 2005.2

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

We measured third-order nonlinear susceptibility spectra in semiconducting single-walled carbon
nanotubes (SWNTs) by the Z-scan method. Im chi^(3) is remarkably enhanced under resonant excitation to
the lowest interband transition, reaching 4×10^-6 esu and 1×10^-7 esu in SWNTs grown by the laser
ablation and HiPco methods, respectively. A comparison of the transient absorption changes evaluated by
degenerate and nondegenerate pump-probe measurements suggests that the resonant enhancement of
Im chi(3) is dominated by a coherent process rather than by saturation of absorption.

DOI： 10.1103/PhysRevLett.94.047404

Photoinduced phase transition in tetrathiafulvalene-p-chloranil observed in femtosecond reflection spectroscopy Reviewed

H. Okamoto, Y. Ishige, S. Tanaka, H. Kishida, S. Iwai, Y. Tokura

Physical Review B Vol. 70 page： 165202-1 - 126502-18 2004.10

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

Photoinduced transitions from ionic sId to neutral sNd and neutral sNd to ionic sId phases in an organic charge
transfer (CT) complex, tetrathiafulvalene-p-chloranil (TTF-CA), were investigated by femtosecond pumpprobe
reflection spectroscopy. Transient reflectivity changes of the intramolecular transition band of TTF
sensitive to the degree of CT between a donor molecule of TTF and an acceptor molecule of CA are measured
as a function of excitation energy, excitation density, and temperature. By adopting the multilayer model for the
analysis of the obtained transient reflectivity spectra, we have derived the time characteristics of amounts and
spatial distributions of photoinduced N sId states in the I sNd phase. The results reveal that the I to N sINd
transition induced by the resonant excitation of the CT band at 4 K is composed of three processes; (1)
formation of a confined one-dimensional (1D) N domain, that is, a sequence of D0A0 pairs, just after the
photoexcitation, (2) multiplication of the 1D N domains to the semimacroscopic N states up to 20 ps within the
absorption depth of the excitation light, and (3) proceeding of the IN transition along the direction normal to
the sample surface. At 77 K near the NI transition temperature sTc=81 Kd, the size of the 1D N domain
initially produced is enlarged and its multiplication process is strongly enhanced. When the excitation energy
is increased, the initial photoproduct is changed from the confined 1D N domain to the positively and negatively
charged N states. The spatial size of the latter is considerably larger than that of the former, indicating
that the introduction of charge carriers makes the neighboring I state strongly unstable. The dynamics of the
photoinduced N to I sNId transition has also been investigated. The 1D I domains are initially produced by
lights, however, they decay within 20 ps even if the density of the I domains is increased. The results demonstrate
that there is a cle

DOI： 10.1103/PhysRevB.70.165202

Charge dynamics of Ca_2-xNa_xCuO₂Cl₂ as a correlated electron system with the ideal tetragonal lattice Reviewed

K. Waku, T. Katsufuji, Y. Kohsaka, T. Sasagawa, H. Takagi, H. Kishida, H. Okamoto, M. Azuma, M. Takano

Physical Review B Vol. 70 page： 134501-1 － 134501-8 2004.10

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

We report the reflectivity and the resistivity measurement of Ca2-xNaxCuO2Cl2 (CNCOC), which has a
single-CuO2-plane lattice with no orthorhombic distortion. The doping dependence of the in-plane optical
conductivity spectra for CNCOC is qualitatively the same to those of other cuprates, but a slight difference
between CNCOC and LSCO, i.e., the absence of the 1.5 eV peak in CNCOC, can be attributed to the smaller
charge-stripe instability in CNCOC. The temperature dependence of the optical conductivity spectra of CNCOC
has been analyzed both by the two-component model (Drude1Lorentzian) and by the one-component
model (extended-Drude analysis). The latter analysis gives a universal trend of the scattering rate Gsvd with
doping. It was also found that Gsvd shows a saturation behavior at high frequencies, whose origin is the same
as that of resistivity saturation at high temperatures.

DOI： 10.1103/PhysRevB.70.134501

Third-order nonlinear susceptibility spectra of CuO chain compounds investigated by the Z-scan method Reviewed

A. Maeda, M. Ono, H. Kishida, T. Manako, A. Sawa, M. Kawasaki, Y. Tokura, H. Okamoto

Physical Review B Vol. 70 page： 125117-1- 125117-7 2004.9

Third-order optical nonlinearity in charge-transfer-type conjugated polymers Reviewed

H. Kishida, K. Hirota. T. Wakabayashi, B. L. Lee, H. Kokubo, T. Yamamoto, H. Okamoto

Physical Review B Vol. 70 page： 115205-1 – 115205-5 2004.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have studied third-order nonlinear optical (NLO) properties of charge-transfer- (CT) type conjugated
copolymer composed of an electron-donating molecule, thiophene, and electron-accepting one, quinoxaline,
using the electroabsorption, two-photon absorption, and third-harmonic generation spectroscopies. The analyses
of the obtained nonlinear optical spectra reveal that the CT character of the excited states leads to small
oscillator strength of linear absorption but large third-order nonlinear susceptibility, resulting in the strong
enhancement of figure of merit for NLO devices.

DOI： 10.1103/PhysRevB.70.115205

Linear and nonlinear optical properties of one-dimensional Mott insulators consisting of Ni-halogen chain and CuO-chain compounds Reviewed

M.Ono, K. Miura, A. Maeda, H. Matsuzaki, H. Kishida, Y. Taguchi, Y. Tokura, M. Yamashita, H. Okamoto

Physical Review B Vol. 70 page： 085101-1 - 085101-20 2004.8

Tuning the electronic structure from charge-transfer insulator to Mott-Hubbard and Peierls insulators in one-dimensional halogen-bridged mixed-metal compounds Reviewed

H. Matsuzaki, K. Iwano, T. Aizawa, M. Ono, H. Kishida, M. Yamashita, and H. Okamoto

Physical Review B Vol. 70 page： 035204-1 – 035204-6 2004.7

Visualization of local valence structures in quasi-one-dimensional halogen-bridged complexes [Ni_1-xPd_x(chxn)₂Br]Br₂ by STM Reviewed

S.Takaishi, H. Miyasaka, K. Sugiura, M. Yamashita, H. Matsuzaki, H. Kishida, H. Okamoto, H. Tanaka, K. Marumoto, H. Ito, S. Kuroda, T. Takami

Angewandte Chemie International Edition Vol. 43 page： 3171-3175 2004.6

Third-harmonic generation in CT-type conjugated polymers Reviewed

H. Kishida, H. Okamoto, B. L. Lee, H. Kokubo, and T. Yamamoto

Transaction of the Materials Research Society of Japan Vol. 29 ( 3 ) page： 981-984 2004.5

Carrier Doping Effect into Quasi-One-Dimensional Bromo-Bridged Ni(III) Complexes with Strong Electron-Correlation by Cu(II) Ions, [Ni_1-xCu_x(chxn)₂Br]Br_2-x Reviewed

M. Yamashita, T. Ono, S. Matsunaga, M. Sasaki, S. Takaishi, F. Iwahori, H. Miyasaka, K. Sugiura, H. Kishida, H. Okamoto, H. Tanaka, Y. Hasegawa, K. Marumoto, H. Ito, S. Kuroda, N. Kimura

Inorganic Chemistry Vol. 42 ( 24 ) page： 7692-7694 2003.10

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

This communication will describe the electron doping effect into NiIII complexes by CuII ions, [Ni1-xCux(chxn)2Br]Br2-x (x = 0.038 and 0.101) by using an electrochemical oxidation method. A drastic increase of electrical conductivity as well as a new absorption band around 0.5 eV in single crystal reflectance spectra was observed by doping CuII ions, indicating the electron doping was successfully made. An ESR result shows unpaired electrons locate in the dx2-y2 orbitals of CuII and have almost no interaction with those of other ions.

DOI： 10.1021/ic0349555

Novel ET-Coordinated Copper(I) Complexes: Syntheses, Structures, and Physical Properties (ET = BEDT-TTF = Bis(ethylenedithio)tetrathiafulvalene) Reviewed

R. Kanehama, M. Umemiya, F. Iwahori, H. Miyasaka, K. Sugiura, M. Yamashita, Y. Yokochi, H. Ito, S. Kuroda, H. Kishida, H. Okamoto

Inorganic Chemistry Vol. 42 ( 22 ) page： 7173-7181 2003.10

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

New molecular charge-transfer complexes of bis(ethylenedithio)tetrathiafulvalene (ET), (ET)Cu2Br4 (1), (ET)2Cu6Br10 (2), (ET)2[Cu4Br6ET] (3), (ET)2Cu2Br4 (4), (ET)2Cu3Br7(H2O) (5), and (ET)2Cu6Br10(H2O)2 (6), have been synthesized by diffusing reaction of ET and CuIIBr2. Their crystal structures and physical properties have been investigated. X-ray analyses revealed that ET molecules coordinated to the copper ions with the sulfur atoms of the ethylenedithio groups in all compounds. The Cu-S distances are found in the range 2.268(5)-2.417(8) Å, being close to the typical CuI-S coordination bond distances. Strong d- interactions between d-electrons of the copper ions and -electrons of the ET molecules can be expected through the Cu-S coordination bonds. ET molecules behave as trans-bidentate ligands bonding to two different copper ions in 1 and 3, as cis-bidentate ligands in 2, 5, and 6, and as monodentate ligands in 4. In the crystal structure of 3, there are two types of ET molecules in the crystal structure, where the first type is a trans-bidentate ligand and the second forms a stacking structure by itself. Compounds 1, 2, 4, and 6 show semiconducting behavior down to low temperature (RT = 1.6 × 10-2 S cm-1 and Ea = 122 meV for 1, RT = 2.1 S cm-1 and Ea = 21 meV for 2, RT = 5.4 × 10-4 S cm-1 and Ea = 239 meV for 4, and RT = 5.1 × 10-2 S cm-1 and Ea = 207 meV for 6). On the other hand, in 3, a metal-like region is observed along the b-axis and c-axis, due to the contribution of stacked ET molecules, and a metal-semiconductor transition occurs at 280 and 270 K, respectively. Also, 5 exhibits metallic conductivity in the temperature ranges 240-300 and 200-300 K along the b-axis and c-axis, respectively, despite the oxidation state of ET with 2+.

DOI： 10.1021/ic0344362

Third-order nonlinear optical spectroscopy in the two-dimensional cuprates Nd₂CuO₄ and La₂CuO₄ Reviewed

H. Kishida, M. Ono, A. Sawa, M. Kawasaki, Y. Tokura, H. Okamoto

Physical Review B Vol. 68 ( 7 ) page： 075101-1 - 075101-5 2003.8

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have measured third-order nonlinear susceptibility (χ(3)) spectra of the two-dimensional (2D) cuprates La2CuO4 and Nd2CuO4 by third-harmonic generation. The |χ(3)| spectra exhibit broad peaks with maximum values of 0.6×10-10 esu in La2CuO4 and 2×10-10 esu in Nd2CuO4. These peaks are attributable to three-photon resonance to the charge transfer (CT) excited state. The χ(3) phase spectrum of Nd2CuO4 has revealed that the two-photon resonance to the even CT state are hidden on the high-energy side of the χ(3) peak. The difference in χ(3) values between the 2D and 1D cuprates is discussed by considering differences in spin-charge coupling and in charge configurations between the 2D and 1D cases.

DOI： 10.1103/PhysRevB.68.075101

Ultrafast Optical Switching to a Metallic State by Photoinduced Mott Transitionin a Halogen-Bridged Nickel-Chain Compound Reviewed

S. Iwai, M. Ono, A. Maeda, H. Matsuzaki, H. Kishida, H. Okamoto, Y. Tokura

Physical Review Letters Vol. 91 ( 5 ) page： 057401-1 - 057401-4 2003.8

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

We demonstrate the ultrafast photoinduced Mott transition from a charge transfer insulator to a
metal in a halogen-bridged Ni-chain compound by pump-probe reflection spectroscopy. Upon the
irradiation of a 130-femtosecond laser pulse, the spectral weight of the gap transition is transferred to
the inner-gap region. When the photoexcitation density exceeds 0:1=Ni site, the Drude-like highreflection
band appears in the infrared region, signaling the formation of a metallic state. The
photogeneration of the metallic state and the subsequent recovery to the original gapped state occur
within a few picoseconds.

DOI： 10.1103/PhysRevLett.91.057401

New charge-transfer salts (ET)₈(Mn^IIBr₄)₂(DCE)₂ and (ET)₃Mn^IIBr₄: Preparations, structures and physical properties (ET = BEDT-TTF, DCE = 1,2-dichloroethane) Reviewed

R. Kanehama, H. Miyasaka, K. Sugiura, M. Yamashita, H. Itou, S. Kuroda, H. Kishida and H. Okamoto

Synthetic Metals Vol. 135-136 ( 4 ) page： 633-634 2003.4

Novel charge-ordering and photo-induced phase transition in MMX chain compounds: R₄[Pt₂(pop)₄I] Reviewed

H. Matsuzaki, H. Kishida, K. Takizawa, M. Yamashita and H. Okamoto

Synthetic Metals Vol. 135-136 ( 4 ) page： 607-608 2003.4

Tuning of spin density wave strength of Ni(III) complexes with strong electron-correlation Reviewed

T. Ono, M. Yamashita, K. Yokoyama, S. Furukawa, T. Manabe, K. Sugiura, T. Ishii, H. Miyasaka, H. Matsuzaki, H. Kishida, H. Okamoto, K. Marumoto, H. Tanaka, Y. Hasegawa, S. Kuroda, H. Itou

Synthetic Metals Vol. 135-136 ( 4 ) page： 357-358 2003.4

Gigantic Third-order Optical Nonlinearity in One-dimensional Mott Insulators Reviewed

H. Kishida, M. Ono, H. Matsuzaki, M. Yamashita, Y. Taguchi, Y. Tokura and H. Okamoto

Synthetic Metals Vol. 135-136 ( 4 ) page： 315-316 2003.4

Large Optical Nonlinearity in 1D and 2D Cuprates Investigated by Third Harmonic Generation Spectroscopy Reviewed

M. Ono, H. Kishida, H. Okamoto, T. Manako, M. Izumi, A. Sawa, M. Kawasaki and Y. Tokura

Synthetic Metals Vol. 135-136 ( 4 ) page： 313-314 2003.4

Coherent valence fluctuation in photo-induced neutral-ionic transition of an one-dimensional charge transfer complex Reviewed

S. Iwai, S. Tanaka, K. Fujinuma, H. Kishida, H. Okamoato, Y. Tokura

Ultrafast Phenomena XIII, Springer Series in Chemical Physics Vol. 71 page： 546-548 2003.4

Synthesis of a New Thiophene/Quinoxaline CT-Type Copolymer with High Solubility and Its Basic Optical Properties Reviewed

T. Yamamoto, B. L. Lee, H. Kokubo, H. Kishida, K. Hirota , T. Wakabayashi, H. Okamoto

Macromolecular Rapid Communications Vol. 24 ( 5-6 ) page： 440 - 443 2003.5

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

A new -conjugated charge-transfer-type copolymer of electron-donating thiophene and electron-accepting quinoxaline was prepared by organometallic polycondensation. The polymer was soluble in organic solvents such as tetrahydrofuran, and showed a UV-vis peak at long wavelengths of 598 nm in chloroform and 629 nm in the film. Its film exhibited a (3) peak in the resonance region with a (3) value comparable to that of regioregular head-to-tail poly(3-hexylthiophene-2,5-diyl).

DOI： 10.1002/marc.200390067

Unprecedented Soliton Formation Mechanism in Quasi-One-Dimensional Chloro-Bridged Pt^II-Pt^IV Mixed-Valence Compound, {[Pt(en)₂][PtCl₂(en)₂]g₃(CuCl₄)₄・12H₂O Reviewed

M. Yamashita, H. Aso, S. Matsunaga, K. Takizawa, K. Nakata, C. Kachi-Terajima, F. Iwahori, T. Ishii, H. Miyasaka, K. Sugiura, T. Kawashima, K. Takai, N. Kuroda,M. Shiro, H. Kishida, H. Okamoto, H. Takahashi, H. Tanaka, K. Marumoto, S. Kuroda

Chemistry Letters Vol. 32 ( 3 ) page： 278-279 2003.3

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

A new type of complex consisting of double liner-chain
structure {[Pt(en)2][PtCl2(en)2]g3(CuCl4)412H2O was synthesized. High concentration (ca. 200 times larger than the literature) of neutral soliton (PtIII component) formation was found. This unprecedented soliton formation mechanism will be discussed.

DOI： 10.1246/cl.2003.278

Electric field effect on charge and lattice dynamics in TTF-QCl₄ and TTF-QBrCl₃ Reviewed

H. Kishida, K. Fujinuma, H. Takamatsu, H. Okamoto, S. Horiuchi, Y. Tokura

Synthetic Metals Vol. 133-134 ( 13 ) page： 633-635 2003.3

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Electroreflectance (ER) spectra are measured on the mixed-stack charge transfer (CT) complexes, tetrathiafulvalane (TTF)-2-bromo-3,5,6-trichloro-p-benzoquinone (QBrCl3) and TTF-p-chloranil (QCl4), showing the neutral–ionic (N–I) phase transition. In the N phase of TTF-QBrCl3, we observe a large ER signal, which originates from the electric field-induced I domains in the N stacks. In contrast, no ER signal is obtained in the N phase of TTF-QCl4. The difference of the ER signal intensity between the two compounds is discussed by taking account of the difference in the degree of the valence instability.

DOI： 10.1016/S0379-6779(02)00357-0

Novel Optical and Magnetic Bistability and Photoinduced Transition in a One-Dimensional Halogen-Bridged Binuclear Pt Complex Reviewed

H. Matsuzaki, T. Matsuoka, H. Kishida, K. Takizawa, H. Miyasaka, K. Sugiura, M. Yamashita, H. Okamoto

Physical Review Letters Vol. 90 ( 4 ) page： 046401-1-046401-4 2003.1

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

In iodine-bridged binuclear Pt compounds, R4Pt2pop4InH2O and R02Pt2pop4InH2O (pop P2O5H2 2 ), electronic structures on the PtPtI chains have been controlled between a diamagnetic chargedensity-
wave (CDW) state and a paramagnetic charge-polarization (CP) state by modification of the
counterions (R, R0) located between chains. In the R C2H52NH2 compound, a pressure-induced CP
to CDW transition with a drastic color change is identified. This transition is accompanied by a large
hysteresis loop within which photoinduced transition between CDWand CP can be driven by selecting
the excitation photon energy.

DOI： 10.1103/PhysRevLett.90.046401

Gigantic optical nonlinearity in one-dimensional Mott insulators Reviewed

H. Okamoto, H. Kishida, M. Ono, H. Matsuzaki, Y. Taguchi, Y. Tokura, M. Yamashita

Nonliear Optics Vol. 29 ( 10-12 ) page： 687 - 695 2002.10

Ultrafast primary process of photo-induced N-I transition and macroscopic oscillation of domain boundary in TTF-CA Reviewed

S. Iwai, S. Tanaka, K. Fujinuma, H. Kishida, H. Okamoto, Y. Tokura

Phase Transitions Vol. 75 ( 7-8 ) page： 807 - 813 2002.10

Magnetic/Conducting Hybrid Compound Composed of 1-D Chain[Mn^II₂Cl₅(EtOH)]_∞^- and BEDT-TTF Stacking Layer Reviewed

H. Miyasaka, Y. Yoshino, T. Ishii, R. Kanehama, T. Manabe,M. Yamashita, H. Nishikawa, I. Ikemoto, H. Kishida, H. Matsuzaki, H. Okamoto

Journal of Solid State Chemistry Vol. 168 page： 418 - 426 2002.11

Tuning of Spin Density Wave Strengths in Quasi-One-DimensionalMixed-Halogen-Bridged Nickel(III) Complexes with Strong ElectronCorrelation, [Ni^III(chxn)₂Cl_1-xBr_x](NO₃)₂ Reviewed

T. Manabe, K. Yokoyama, S. Furukawa, C. Kachi-Terajima, K. Nakata, F. Iwahori, H. Miyasaka, K. Sugiura, M. Yamashita, H. Kishida, H. Okamoto

Inorganic Chemistry Vol. 41 ( 20 ) page： 4993 - 4995 2002.9

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

This communication describes the syntheses of the quasi-onedimensional
mixed-halogen-bridged NiIII complexes with strong
electron correlation [Ni(chxn)2Cl1-xBrx](NO3)2 and the tuning of the
spin density wave strengths of these compounds. If the Cl 3p and
Br 4p make one band in the compounds, we should observe a
single peak in the electronic spectra. As a result, we should observe
the single peak from 1.45 to 2.00 eV depending on the mixing
ratios of Cl and Br ions. Therefore, the Cl 3p and Br 4p make one
band. Then, we have succeeded in tuning the spin density wave
strengths of the NiIII complexes with the strong electron correlation
by mixing the bridging halogen ions successively.

DOI： 10.1021/ic025654i

Photoemission study of quasi-one-dimentional halogen-bridged compound [Ni(chxn)₂Br]Br₂ Reviewed

S. FUJIMORI, A. INO,T. OKANE, A. FUJIMORI, K. OKADA, T. MANABE, M. YAMASHITA, H. KISHIDA, H. OKAMOTO

Surface Review and Letters Vol. 9 ( 2 ) page： 1065 - 1069 2002.4

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

We report results of the angle-resolved photoemission experiments on a quasi-one-dimensional halogenbridged
complex [Ni(chxn)2Br]Br2 (chxn = 1R, 2R-cyclohexanediamine), which is a one-dimensional
Heisenberg spin chain with S = 1=2 and J 3600 K. The expected two dispersions, originated with
spin{charge separations as have been observed in other quasi-one-dimensional electron systems like
Sr2CuO3, are not clearly observed in this compound. Instead, only one \band" having about 0.5 eV
energy dispersion is found in the half of the Brillouin zone.

DOI： 10.1142/S0218625X02003354

Physical Properties of Quasi-One-Dimensional Mixed-Metal and Mixed-Halogen Complexese, Ni_1-xPd_x(chxn)₂Cl_yBr_1-yY₂ Reviewed

T. Manabe, K. Yokoyama, T. Ishii, H. Miyasaka, H. Matsuzaka, M. Yamashita, T. Kawashima, H. Matsuzaki, H. Kishida, H. Okamoto, K. Marumoto, H. Tanaka, H. Itoh, S. Kuroda

Molecular Crystals and Liquid Crystals Vol. 376 ( 1 ) page： 165-170 2002

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

A series of single crystals of quasi-one-dimensional Ni-Pd mixed-metal MX-chain compounds, Ni 1-x Pd x (chxn) 2 Br 3 , and mixed-halogen MX-chain compounds, Ni(chxn) 2 Cl y Br 1-y (NO 3 ) 2 have been obtained by electrochemical oxidation methods. In order to investigate the electronic states of these compounds, the optical conductivity spectra have been measured. These results indicate that the electronic states of the Ni compounds can be controlled by forming the mixed-metal or mixed-halogen systems.

DOI： 10.1080/713738467

Crystal and Electronic Structures of Quasi-One-Dimensional Halogen-Bridged Binuclear Platinum Complexes, {(C_nH_2n+1)₂NH₂}4[Pt₂(pop)₄I] (n=2-6) Reviewed

K. Takizawa, T. Ishii, H. Miyasaka, H. Matsuzaka, M. Yamashita, T. Kawashima, H. Matsuzaki, H. Kishida, H. Okamoto

Molecular Crystals and Liquid Crystals Vol. 376 ( 1 ) page： 159 - 164 2002

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

The crystal structures of (C n H 2n+1 ) 2 NH 2 4 [Pt 2 (pop) 4 I] (pop=O(PO 2 H) 2 2- , n=2-6) have been determined. Judging from the results of the X-ray structural analyses and Raman spectra, 1-D electronic structures of these compounds are consider to be Pt 2+ -Pt 3+ -X Pt 2+ -Pt 3+ -X charge-polarized states.

DOI： 10.1080/10587250210759

Angle-Resolved Photoemission Study of the MX-Chain Compound [Ni(chxn)₂Br]Br₂: Spin-Charge Separation in Hybridized d-p Chains Reviewed

S. Fujimori, A. Ino, T. Okane, A. Fujimori, K. Okada, T. Manabe, M. Yamashita, H. Kishida, H. Okamoto

Physical Review Letters Vol. 88 ( 24 ) page： 247601-1 - 247601-4 2002.6

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

We report on the results of angle-resolved photoemission experiments on a quasi-one-dimensional (1D) MX-chain compound [Ni(chxn)2Br]Br2, which shows a gigantic nonlinear optical effect. A “band" having about 500 meV energy dispersion is found in the first half of the Brillouin zone, but disappears at kb/π∼1/2. These spectral features are well reproduced by the d-p chain model with a small charge-transfer energy Δ compared with that of 1D Cu-O compounds. We propose that this smaller Δ is the origin of the absence of clear spin-charge separation in the photoemission spectra and the strong nonlinear optical effect.

DOI： 10.1103/PhysRevLett.88.247601

Tuning of Electronic Structures of Quasi-One-Dimensional Bromo-Bridged Ni(III) Complexes with Strong Electron-Correlation by Doping of Co(III) Ions, [Ni_1-xCo_x(Chxn)₂Br]Br#D2DR Reviewed

M. Yamashita, K. Yokoyama, S. Furukawa, T. Manabe, T. Ono, K. Nakata, C. Kachi-Terajima, F. Iwahori, T. Ishii, H. Miyasaka, K. Sugiura, H. Matsuzaki, H. Kishida, H. Okamoto, H. Tanaka, Y. Hasegawa, K. Marumoto, H. Ito, and S. Kuroda

Inorganic Chemistry Vol. 41 ( 8 ) page： 1998 - 2000 2002.3

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

We have succeeded in synthesizing the NiIII complexes doped by CoIII ions, [Ni1-xCox(chxn)2Br]Br2 (x = 0, 0.043, 0.093, and 0.118) by using an electrochemical oxidation method. The single-crystal reflectance spectrum of x = 0.118 shows an intense CT band about 0.5 eV, which is lower than that of [Ni(chxn)2Br]Br2 (1.3 eV). The single-crystal electrical conductivities at room temperature of these compounds increase with increase of the amounts of doping of CoIII ions. In the ESR spectra, peak-to-peak line widths Hpp at room temperature change about 600 G in [Ni(chxn)2Br]Br2 to 200 G in x = 0.118. Such a large x dependence of Hpp seems to be ascribed to the increasing contribution from the increasing Curie spins which have smaller line width. Therefore, we have tuned the electronic structures of quasi-one-dimensional bromo-bridged NiIII complexes with strong electron correlations by doping of CoIII ions.

DOI： 10.1021/ic011326r

Ultrafast Optical Switching from an Ionic to a Neutral State in Tetrathiafulvalene-p-Chloranil (TTF-CA) Observed in Femtosecond Reflection Spectroscopy Reviewed

S. Iwai, S. Tanaka, K. Fujinuma, H. Kishida, H. Okamoto, and Y. Tokura

Physical Review Letters Vol. 88 ( 5 ) page： 057402-1-057402-4 2002.2

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

Ultrafast optical switching from an ionic ( I) to a neutral ( N) state in TTF-CA was observed in femtosecond reflection spectroscopy. Charge transfer excitation in the I phase produces N donor ( D0) acceptor ( A0) strings within 2 ps. These initial N states decay with a lifetime of 300 ps at 4 K, but rather multiply leading to macroscopic I-N conversion within 20 ps at 77 K just below the N-I transition temperature TNI. Near TNI, we also found the evidence for the coherent motion of the macroscopic N-I domain boundary with a period of 85 ps.

DOI： 10.1103/PhysRevLett.88.057402

Large third-order optical nonlinearity of Cu-O chains investigated by third-harmonic generation spectroscopy Reviewed

H. Kishida, M. Ono, K. Miura, H. Okamoto, M. Izumi, T. Manako, M. Kawasaki, Y.Taguchi, Y. Tokura, T. Tohyama, K. Tsutsui, and S. Maekawa

Physical Review Letters Vol. 87 ( 17 ) page： 177401-1 - 177401-4 2001.10

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

Spectra of the third-order nonlinear susceptibility χ(3) have been investigated for one-dimensional Mott insulators, Sr2CuO3 and Ca2CuO3, by applying the third-harmonic generation (THG) spectroscopy on their single-crystalline thin films. The three-photon resonance to the lowest charge-transfer (CT) state with odd parity strongly enhances χ(3), which is of the order of 10-9 esu. The two-photon resonant structure unravels the even-CT state, located close to the odd-CT state. Two types of χ(3) spectra obtained from THG and the electroreflectance measurements are explained based on the concept of spin-charge separation.

DOI： 10.1103/PhysRevLett.87.177401

Orientation-controlled epitaxy of A₂CuO₃ (A: Sr, Ca) films with large optical nonlinearity Reviewed

T. Manako, Y. Okimoto, M. Izumi, S. Shinomori, M. Kawasaki, H. Kishida, H. Okamoto, T. Fukumura, M. Ohtani, Y. Tokura

Applied Physics Letters Vol. 79 ( 12 ) page： 1754 - 1756 2001.9

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

The one-dimensional Cu–O chains responsible for the large optical nonlinearity in Sr2CuO3 (SCO) and Ca2CuO3 (CCO) are aligned in one direction in films grown on LaSrAlO4 (LSAO) (1 0 0) substrates by using pulsed laser deposition. The CCO films deposited directly on lattice matched LSAO substrates have a single orientation with high crystallinity, while the SCO films include small portions of misoriented domains. Using a simple model of lattice mismatch, we developed a Sr2TiO4 buffer layer in order to grow orientation-controlled SCO films with both high crystallinity and a sharp optical absorption edge. This technique will be a key to fabricating ultrafast all-optical switches with a waveguide structure.

DOI： 10.1063/1.1402161

Electromodulation spectroscopy in ferroelectric CT complex: TTF-CA Reviewed

H. Kishida, K. Fujinuma and H. Okamoto

Synthetic Metals Vol. 120 ( 1-3 ) page： 909 - 910 2001.3

Highly Oriented Langmuir-Blodgett Films of Helical Polysilanes and Their Optical Properties Reviewed

H. Tachibana, H. Kishida, and Y. Tokura

Langmuir Vol. 17 ( 2 ) page： 437 - 440 2001.1

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

Thin films of a helical polysilane with chiral substituents were fabricated using a Langmuir-Blodgett (LB) method. The polarized absorption and photoluminescence spectra show the high anisotropy for the LB films with the polymer backbone lying in-plane along the dipping direction. The anisotropy of the lowest exciton absorption band can be enhanced by annealing the LB films. With use of the oriented LB film, we have revealed the one-dimensional exciton structures characteristic of polysilanes with helical conformations by measurements of electroabsorption spectra, compared with those of polysilanes of other conformations such as trans-planar and alternating trans-gauche backbone structures. The large binding energies of the lowest exciton are generic in the one-dimensional regular polysilanes, irrespective of the conformations.

DOI： 10.1021/la0010774

Charge Fluctuation in Quasi-One-Dimensional Halogen-Bridged Platinum Binuclear Mixed-Valence Compounds, A4[Pt₂(pop)₄I]・nH₂O Reviewed

T. Kawashima, S. Miya, T. Manabe, M. Yamashita, K. Takizawa, T. Ishii, H. Matsuzaka, T. Sonoyama, H. Kitagawa,T. Mitani, H. Matsuzaki, H. Kishida, H. Okamoto, R. Ikeda

Molecular Crystals and Liquid Crystals Vol. 342 ( 1 ) page： 145 - 150 2000.5

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

New quasi-one-dimensional halogen-bridged platinum binuclear mixed-valence compounds, A4[Pt2(pop)4I]·nH2O (A=alkaline metal and NH4, and; n=0, 2 and 4) have been synthesized. The Li, Na and K compounds take structures -Pt2.5+-Pt2.5+-X-Pt2.5+-Pt2.5+-X- (a). On the other hand, the Cs and Rb compounds take structures Pt2+-Pt2+X-Pt3+-Pt3+-X (b). Interestingly, the NH4 compound takes a phase transition between (a) and (b) around 200K.

DOI： 10.1080/10587250008038258

Photoluminescence from pendant dye molecules mediated by exciton transport on helical polysilane chains Reviewed

H. Tachibana, H. Kishida, Y. Tokura

Applied Physics Letters Vol. 77 ( 16 ) page： 2443 - 2445 2000.10

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

We have synthesized helical polysilanes on which the pendant groups are partly substituted by dye molecules. The introduction of a few percent of dye molecules into the substituents enhances the luminescent efficiency of the visible region, by behaving as luminescence centers. We have demonstrated that the excitation energy is transferred efficiently by free excitons on the Si backbones to reach the luminescence centers, where energy transfer occurs from the exciton to the dye molecule, and as a result sensitized luminescence occurs. The exciton transfer is found to occur over 50–100 monomer units on the polysilane backbone. This approach will open the way to fabricating a wavelength-tunable luminous device by utilizing the exciton transport on Si chains.

DOI： 10.1063/1.1318395

Gigantic optical nonlinearity in one-dimensional Mott-Hubbard insulators Reviewed

H. Kishida, M. Matsuzaki, H. Okamoto, T. Manabe, M. Yamashita, Y. Taguchi, and Y. Tokura

Nature Vol. 405 page： 929-932 2000.6

Photoexcitations in the strongly correlated 1-D electron system of halogen-bridged Ni compounds Reviewed

H. Okamoto, H. Kishida, M. Ono, H. Matsuzaki, M. Yamashita and T. Manabe

Journal of Luminescence Vol. 87-89 page： 204 - 206 2000.5

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

To study nature of photo-excited states in one-dimensional (1D) strongly correlated electron systems, we have synthesized the halogen(X)-bridged Ni compounds, [Ni(chxn)2X]Y2 (X=Cl or Br; Y=Cl, Br, NO3 or ClO4; (chxn)=cyclohexanediamine), which have 1D Ni–X chains. These Ni compounds are charge-transfer (CT) insulators, showing strong CT transitions from the occupied halogen p band to the Ni d upper Hubbard band. The CT transition energies can be systematically controlled from 1.3 to 2.0 eV by the choice of the bridging-halogen ions X and the counter ions Y. From the excitation profiles of the photoconductivities, excitonic effects in the Ni-X chains have been found to depend strongly on the degree of pd hybridization.

DOI： 10.1016/S0022-2313(99)00262-8

Finite chain-length effect on nonlinear optical response in polysilane as investigated by electroabsorption spectroscopy Reviewed

H. Kishida, H. Tachibana, K. Sakurai, M. Matsumoto, Y. Tokura

Physical Review B Vol. 54 ( 20 ) page： R14254 - R14256 1996.11

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have investigated the electroabsorption spectrum for a thin film of the silicon oligomer Si10(CH3)22, a finite-chain analog of quasi-one-dimensional semiconductor polysilanes. The obtained spectrum can be well reproduced by a four-level model in which a one-photon-forbidden state is located between two one-photon-allowed states. By comparison with the spectra of polysilanes, it was found that the transition dipole moment between the excited states decreases significantly with a decrease of chain length. This can be ascribed to the confinement of the excited states.

DOI： 10.1103/PhysRevB.54.R14254

Phase retrieval in nonlinear optical spectroscopyby the maximum-entropy method: anapplication to the |x⁽³⁾| spectra of polysilane Reviewed

E. M. Vartiainen, K.-E. Peiponen, H. Kishida, and T. Koda

Journal of the Optical Society of America B Vol. 13 ( 10 ) page： 2106-2114 1996.10

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

A method of phase retrieval from the experimental modulus ux (3)u spectra of third-order nonlinear optical susceptibility
is presented on the basis of the maximum-entropy model. This method enables one to derive the
real and the imaginary parts of x (3) without using the nonlinear Kramers–Kronig calculation, which is usually
hazardous in nonlinear optical spectroscopy because of the limited range of measurements. Theoretical and
experimental modulus spectra of polysilane are analyzed. The results from the experimental modulus are
compared with the Kramers–Kronig calculations as well as with the measured phase values. It is also shown
how the method can be optimized to reduce the distortions that result from noise in the calculated spectra.

DOI： 10.1364/JOSAB.13.002106

Nature of one-dimensional excitons in polysilanes Reviewed

T. Hasegawa, Y. Iwasa, T. Koda, H. Kishida, Y. Tokura, S. Wada, H. Tashiro, H. Tachibana, M. Matsumoto

Physical Review B Vol. 54 ( 16 ) page： 11365 - 11374 1996.10

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

One-dimensional (1D) exciton states have been studied by nonlinear optical spectroscopy on organosilicon polymer polysilanes (PS's). From systematic variation of the linear and nonlinear optical spectra upon changing the backbone conformation, the following two characteristic exciton parameters have been evaluated; the ratio |χ(3)|/α of the modulus of third-order nonlinear optical susceptibility |χ(3)| to the absorption coefficient α; and the energy difference ΔE12 between the lowest and second lowest exciton energies E1 and E2, which are theoretically related, respectively, to the Bohr radius and to the binding energy of excitons. It was found that |χ(3)|/α increases, whereas ΔE12 remains almost unchanged, with increasing valence and conduction-band widths. These features cannot be accounted for either by the Wannier- or Frenkel-type exciton model. From analysis by a unified 1D exciton model, it has been concluded that the 1D excitons in PS's represent a unique system having an intermediate character in between the Frenkel- and Wannier-exciton regimes, where the on-site Coulomb (or exchange) interactions play a crucial role in determining the characteristic exciton structures as observed.

DOI： 10.1103/PhysRevB.54.11365

Optical Spectra of Silicon Oligomers Reviewed

H. Kishida, H. Tachibana, K. Sakurai, M. Matsumoto, S. Abe and Y. Tokura

Journal of the Physical Society of Japan Vol. 65 ( 6 ) page： 1578-1581 1996.6

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Optical absorption spectra have been measured for finite-chain analogs of linear polysilane, silicon oligomers CH3[Si(CH3)2]nCH3, with controlled chain length n(=2 to 16). The intense lowest electronic absorption peak and its higher-lying side bands, which correspond to the one-dimensional exciton series in the infinite chain, shift to higher energy with decrease of the chain length because of the confinement of the excited states. The oscillator strength of the main absorption peak increases with the chain length, while the linewidth of the main peak drastically decreases, especially in the region n=2 to 6. These finite size effects of the electronic (excitonic) absorption are argued in terms of spatial extension of the excited states, motional narrowing and electron correlation effect.

DOI： 10.1143/JPSJ.65.1578

Finite-size effects in the exciton-phonon coupled system Reviewed

H. Kishida, N. Nagaosa, and Y. Tokura

Physical Review B Vol. 53 ( 19 ) page： 12574-12576 1996.5

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The size dependence of the optical spectra of the exciton-phonon coupled system is studied theoretically. As the sample size N increases, the optical spectrum generally crosses over from Gaussian to Lorentzian with motional narrowing due to the increased itineracy of the exciton. It is found that this crossover depends strongly on the ratios W/D and W/(ħωD) (W is the exciton bandwidth, D the site energy fluctuation, and ωD the Debye frequency). Even nonmonotonic behavior is found in the numerical study.

DOI： 10.1103/PhysRevB.53.12574

Visible luminescence from branched silicon polymers Reviewed

KISHIDA H, TACHIBANA H, MATSUMOTO M, TOKURA Y H. Kishida, H. Tachibana, M. Matsumoto, Y. Tokura

Journal of Applied Physics Vol. 78 ( 5 ) page： 3362-3366 1995.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Luminescence spectra and their variation with temperature have been investigated for solid films of poly(methylphenylsilane) and its branched analogs. Introduction of branching points to the polymers enhances the broad luminescence band in the visible region while suppressing the sharp UV luminescence band due to the resonant recombination of the exciton. The intensity of the visible luminescence is observed to keep on increasing with decreasing temperature in contrast with the nearly temperature-independent intensity of the resonant luminescence. The behavior is interpreted in terms of phonon-assisted tunneling between luminescence centers and nonradiative ones.

DOI： 10.1063/1.359962

Electro-modulation spectroscopy on excitons in β-carotene and related polyenes Reviewed

T. Koda, A. Ishiguro, N. Kaneta, H. Kishida, Y. Tokura, and K. Ishikawad

Synthetic Metals Vol. 71 ( 1-3 ) page： 1723-1724 1995.4

Nonlinear optical spectroscopy on polysilanes: Dependence of exciton states on polymer backbone conformations Reviewed

T. Hasegawa, Y. Iwasa, T. Koda, H. Kishida, Y. Tokura, S. Wada, H. Tashiro, H. Tachibana, M. Matsumoto and R. D. Miller

Synthetic Metals Vol. 71 page： 1679-1680 1995.4

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

The third-order nonlinear optical (NLO) susceptibility χ(3)(-3ω;ω,ω,ω) have been measured on spin-coated films of three kinds of polysilanes (PS's) with various backbone conformations, in a wide range of fundamental wavelength, by means of third-harmonic generation (THG) measurement. The experimental results show that their quasi-one-dimensional (Q1D) exciton level structures and their optical nonlinearity systematically change, with their backbone conformation changes. As compared with the theoretical calculation by 1D exciton model, the experimental feature indicates that the on-site electron correlation takes important roles in Q1D exciton states of PS's.

DOI： 10.1109/STSM.1994.835738

Optical properties of branched silicon polymers Reviewed

H. Kishida, H. Tachibana, M. Matsumoto, and Y. Tokura

Japanese Journal of Applied Physics, Supplement Vol. 34 ( 1 ) page： 104-106 1995

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Optical properties of the branched and network silicon polymers have been studied. By introduction of the branching points onto the polysilanes, the absorption spectrum, which is characterized by a sharp excitonic peak, changes gradually into the amorphous-like one, while the uv luminescence disappears immediately with branching and the broad visible luminescence shows up. The network polymers, in which all backbones atoms are coordinated by three other backbone atoms in the limit of branching, show amorphous-like absorption spectra. by Ge-substitution for Si atoms in the backbone of network polymers, and absorption edge as well as the luminescence peak shift to the lower energy side by c.a. 0.5eV.

DOI： 10.7567/JJAPS.34S1.104

Electric-field-induced second-harmonic generation mediated by one-dimensional excitons in polysilanes Reviewed

H. Kishida, T. Hasegawa, Y. Iwasa, T. Koda, Y. Tokura, H. Tachibana, M. Matsumoto, S. Wada, T. T. Lay, and H. Tashiro

Physical Review B Vol. 50 ( 11 ) page： 7786-7792 1994.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The third-order nonlinear-susceptibility χ(3)(-2ω;ω,ω,0) spectrum has been investigated for thin films of linear-Si-chain compounds, poly(dihexylsilane), by measurements of electric-field-induced second-harmonic generation (EFISHG). In the χ(3) spectrum for EFISHG, two-photon resonance structures to the first and second levels of one-dimensional excitons were observed. The observed χ(3) spectrum can be accounted for by considering multiple optical processes in the one-dimensional excitonic series characteristic of the Si-chain system.

DOI： 10.1103/PhysRevB.50.7786

Optical spectra of Si/Ge-network copolymers : [Si(C₆H₁₃)]_1-x[Ge(C₆H₁₃)]_x Reviewed

H. Kishida, H. Tachibana, M. Matsumoto, and Y. Tokura

Applied Physics Letters Vol. 65 ( 11 ) page： 1358-1360 1994.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Optical properties of silicon- and germanium-based network copolymers, [Si(C6H13)]1-x[Ge(C6H13)]x, have been investigated for various Si/Ge compositions (x). The backbone Si/Ge atoms are coordinated by the three other Si/Ge backbone atoms in the polymers. These Si/Ge copolymers show the absorption spectra which are typical of amorphous semiconductors. Their color continuously traverses the visible range with x, which is due to the change of the band gap (Tauc gap) energy as well as to the presence of localized subgap states. The Si/Ge copolymer shows a broad band of luminescence in the visible region. The luminescence band maximum was observed to shift by 0.5 eV with change of the Si/Ge ratio.

DOI： 10.1063/1.112051

Nonlinear optical study of polysilanes Reviewed

T. Hasegawa, Y. Iwasa, T. Koda, H. Kishida, Y. Tokura, S. Wada, H. Tashiro,H. Tachibana, M. Matsumoto, and R. D. Miller

Supplement B to Journal of the physical society of Japan Vol. 63 page： 64-81 1994

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

Optical properties of the branched and network silicon polymers have been studied. By introduction of the branching points onto the polysilanes, the absorption spectrum, which is characterized by a sharp excitonic peak, changes gradually into the amorphous-like one, while the uv luminescence disappears immediately with branching and the broad visible luminescence shows up. The network polymers, in which all backbones atoms are coordinated by three other backbone atoms in the limit of branching, show amorphous-like absorption spectra. By Ge-substitution for Si atoms in the backbone of network polymers, an absorption edge as well as the luminescence peak shift to the lower energy side by c.a. 0.5eV.

Control of electronic structures of polysilanes and polygermanes Reviewed

Y. Tokura, H. Tachibana, H. Kishida, Y. Moritomo, and M. Matsumoto

Supplement B to Journal of the physical society of Japan Vol. 63 page： 30-45 1994

Crystal structure and optical properties of polymorphic octasilacubane Reviewed

H. Tachibana, M. Goto, M. Matsumoto, H. Kishida, and Y. Tokura

Applied Physics Letters Vol. 64 page： 2509-2510 1994.5

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

Single crystal x-ray crystallographic analysis of tert-butyloctasilacubane showed that a new polymorphic form ( form) exists with a slightly modified shape of the Si cage as compared with the previously reported form ( form) [K. Furukawa, M. Fujino, and N. Matsumoto, Appl. Phys. Lett. 60, 2744 (1991)]. Spectroscopic investigations of the single crystal indicate that the electronic band gap and luminescence band position differ by ~0.4 eV between the polymorphs, signaling the sensitivity of the electronic structure to the distortion of the octasilacubane framework. Applied Physics Letters is copyrighted by The American Institute of Physics.

DOI： 10.1063/1.111556

Dispersion relation in the third-order electric susceptibility for polysilane film Reviewed

H. Kishida, T. Hasegawa, Y. Iwasa, T. Koda, and Y. Tokura

Physical Review Letters Vol. 70 ( 24 ) page： 3724-3727 1993.6

Nonlinear optical properties of polysilanes Reviewed

T. Hasegawa, Y. Iwasa, H. Kishida, T. Koda, Y. Tokura, H. Tachibana, and Y. Kawabata

Molecular Crystals and Liquid Crystals Vol. 217 page： 25-30 1992.6

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

We have measured a spectrum of third-order nonlinear optical susceptibility |x (3)(-3;,,)| of -conjugated polysilane, poly(di-n-hexylsilane) (PDHS), by means of third-harmonic generation (THG) measurement, in the fundamental photon energy region from 0.56 eV to 2.15 eV. The obtained | x (3)(3; , , )| spectrum exhibits three peaks. These peaks are interpreted as the multi-photon resonance enhancement to the one-dimensional exciton states. This exciton model can be applied also to the nonlinear optical response of other conjugated polymers.

DOI： 10.1080/10587259208046871

Two-photon resonant third-harmonic generation in polysilanes Reviewed

T. Hasegawa, Y. Iwasa, H. Kishida, T. Koda, Y. Tokura, H. Tachibana, and Y. Kawabata

Physical Review B Vol. 45 ( 11 ) page： 6317-6320 1992.3

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

Third-order nonlinear-optical susceptibility spectra ‖χ(3)(-3ω;ω,ω,ω)‖ have been obtained for poly(dihexylsilane) (PDHS) and poly(dibutylsilane) (PDBS) films by third-harmonic generation (THG) measurements for a fundamental photon energy region from 1.90 to 2.15 eV, which covers the two-photon absorption (TPA) for PDHS but not for PDBS. The ‖χ(3)‖ spectrum for PDHS shows a prominent peak at about 2.08 eV with a maximum value of about 2.3×10-12 esu, while there is no enhancement effect in PDBS in the same fundamental photon energy region. These results provide direct evidence for the two-photon-resonant THG process in polysilanes due to the one-photon-forbidden 1Ag exciton detected by TPA and electroabsorption measurements.

DOI： 10.1103/PhysRevB.45.6317

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