研究者詳細 - 岸田　英夫

論文 - 岸田　英夫

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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) 査読有り

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

Molecular Crystals and Liquid Crystals 376 巻 ( 1 ) 頁： 159 - 164 2002年

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Physical Review Letters 88 巻 ( 24 ) 頁： 247601-1 - 247601-4 2002年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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 41 巻 ( 8 ) 頁： 1998 - 2000 2002年3月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Physical Review Letters 88 巻 ( 5 ) 頁： 057402-1-057402-4 2002年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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 87 巻 ( 17 ) 頁： 177401-1 - 177401-4 2001年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Applied Physics Letters 79 巻 ( 12 ) 頁： 1754 - 1756 2001年9月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

H. Kishida, K. Fujinuma and H. Okamoto

Synthetic Metals 120 巻 ( 1-3 ) 頁： 909 - 910 2001年3月

Highly Oriented Langmuir-Blodgett Films of Helical Polysilanes and Their Optical Properties 査読有り

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

Langmuir 17 巻 ( 2 ) 頁： 437 - 440 2001年1月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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 342 巻 ( 1 ) 頁： 145 - 150 2000年5月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

H. Tachibana, H. Kishida, Y. Tokura

Applied Physics Letters 77 巻 ( 16 ) 頁： 2443 - 2445 2000年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Nature 405 巻頁： 929-932 2000年6月

Photoexcitations in the strongly correlated 1-D electron system of halogen-bridged Ni compounds 査読有り

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

Journal of Luminescence 87-89 巻頁： 204 - 206 2000年5月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Physical Review B 54 巻 ( 20 ) 頁： R14254 - R14256 1996年11月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Journal of the Optical Society of America B 13 巻 ( 10 ) 頁： 2106-2114 1996年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Physical Review B 54 巻 ( 16 ) 頁： 11365 - 11374 1996年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Journal of the Physical Society of Japan 65 巻 ( 6 ) 頁： 1578-1581 1996年6月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Physical Review B 53 巻 ( 19 ) 頁： 12574-12576 1996年5月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Journal of Applied Physics 78 巻 ( 5 ) 頁： 3362-3366 1995年9月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

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 査読有り

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

Synthetic Metals 71 巻 ( 1-3 ) 頁： 1723-1724 1995年4月

Nonlinear optical spectroscopy on polysilanes: Dependence of exciton states on polymer backbone conformations 査読有り

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

Synthetic Metals 71 巻頁： 1679-1680 1995年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

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

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