Faculty Profiles - KISHIDA Hideo

Papers - KISHIDA Hideo

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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

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