Papers - HAMANAKA Yasushi
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Y. Hamanaka, K. Fukuta, A. Nakamura, L. M. Liz-Marzán, and P. Mulvaney
Applied Physics Letters 84 4938 - 4940 2004.04
Language：English Publishing type：Research paper (scientific journal)
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Ultrafast relaxation dynamics of photoexcited carriers in metallic and semioconducting single-walled carbon nanotubes Reviewed
M. Ichida, Y. Hamanaka, H. Kataura, Y. Achiba, and A. Nakamura
Journal of the Physical Society of Japan 73 3479 - 3483 2004.04
Language：English Publishing type：Research paper (scientific journal)
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Ultrafast nonlinear optical response in silica-capped gold nanoparticle films Reviewed
Y. Hamanaka, K. Fukuta, A. Nakamura, L. M. Liz-Marzán, and P. Mulvaney
Journal of Luminescence 108 365 - 369 2004.04
Language：English Publishing type：Research paper (scientific journal)
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Critical behavior of a photo-disordered spin system in epitaxial CrO2 films Reviewed
T. Yoshii, Y. Hamanaka, Y. Moritomo, and A. Nakamura
Journal of Luminescence 108 225 - 228 2004.04
Language：English Publishing type：Research paper (scientific journal)
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Dispersion of third-order optical susceptibility around surface plasmon resonance in silver nanocrystal-glass composites Reviewed
Y. Hamanaka, N. Hayashi, A. Nakamura, and S. Omi
Journal of the Optical Society of America B 20 1227 - 1232 2003.04
Language：English Publishing type：Research paper (scientific journal)
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Morphology of self-assembled merocyanine J-aggregates in films studied by scanning near-field optical microscope Reviewed
Y. Hamanaka, O. Kawasaki, T. Yamauchi, and A. Nakamura
Chemical Physics Letters 378 47 - 54 2003.04
Language：English Publishing type：Research paper (scientific journal)
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Dispersion curves of complex third-order optical susceptibilities around the surface plasmon resonance in Ag nanocrystal-glass composites Reviewed
Yasushi Hamanaka, Arao Nakamura, Nobuhiro Hayashi, Shigeaki Omi
Journal of the Optical Society of America B: Optical Physics 20 ( 6 ) 1227 - 1232 2003
Language：English Publishing type：Research paper (scientific journal) Publisher：Optical Society of America (OSA)
We have investigated dispersion curves of a third-order nonlinear optical susceptibility, χ(3), around the surface-plasmon resonance energy for a Ag nanocrystal-glass composite by means of z-scan and degenerate four-wave mixing measurements. Real and imaginary parts of χ(3) of the composite that contains Ag nanocrystals with an average diameter of 7 nm have been measured at room temperature. The imaginary part of χ(3) exhibits a negative peak near the surface-plasmon resonance, and the largest negative value is -(1.5 ± 0.2) × 10-10 electrostatic units (esu). The real part of χ(3) changes from -(4 ± 2) × 10-11 esu at the lower energy side of the surface-plasmon peak to +(4.4 ± 0.5) × 10-11 esu at the higher energy side. We calculated dispersion curves for the composite assuming that the real and the imaginary parts of the dielectric constant of metal nanocrystals change by optical excitations that are due to the creation of hot electrons. The obtained dispersion curves show a characteristic feature that differs from the exciton system in semiconductors. © 2003 Optical Society of America.
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Exciton delocalization length of merocyanine J-aggregates in Langmuir-Blodgett films studied from linear and nonlinear absorption measurements Reviewed
Y. Hamanaka, H. Kurasawa, A. Nakamura, Y. Uchiyama, K. Marumoto, and S. Kuroda
Chemical Physics Letters 363 233 - 240 2002.04
Language：English Publishing type：Research paper (scientific journal)
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Femtosecond laser spectroscopy of In0.53Ga0.47As/InP multiple quantum wells: interfacial roughness and photoexcited carrier relaxation Reviewed
A. Nakamura, K. Tanase, I. Yamakawa, T. Yamauchi, Y. Hamanaka, R. Oga, Y. Fujiwara, and Y. Takeda
Journal of Luminescence 100 259 - 267 2002.04
Language：English Publishing type：Research paper (scientific journal)
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Ultrafast relaxation dynamics of photoexcited states in semiconducting single-walled carbon nanotubes Reviewed
M. Ichida, Y. Hamanaka, H. Kataura, Y. Achiba, and A. Nakamur
Physica B 323 237 - 238 2002.04
Language：English Publishing type：Research paper (scientific journal)
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Sol-gel derived gold nanoclusters in silica glass possessing large optical nonlinearities S. Tamil Selvan, T. Hayakawa, M. Nogami, Y. Kobayashi, L. M. Liz-Marzán, Y. Hamanaka, and A. Nakamura Reviewed
S. Tamil Selvan, T. Hayakawa, M. Nogami, Y. Kobayashi, L. M. Liz-Marzán, Y. Hamanaka, and A. Nakamura
Journal of Physical Chemistry B 106 10157 - 10162 2002.04
Language：English Publishing type：Research paper (scientific journal)
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Structure and photoexcited carrier dynamics in InGaAs/InP multiple quantum wells Reviewed
I. Yamakawa, M. Shiozawa, Y. Wakui, K. Tanase, Y. Hamanaka, A. Nakamura, R. Oga, Y.
Technical Report of IEICE 35 - 40 2002
Language：English Publishing type：Research paper (scientific journal)
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Ultrafast relaxation dynamics of photoexcited carriers in single-walled carbon nanotubes Reviewed International journal
M. Ichida, Y. Hamanaka, H. Kataura, Y. Achiba, and A. Nakamura
Proceedings of the 26th International Conference on the Physics of Semiconductors, Edinburgh, 2002
Language：English Publishing type：Research paper (international conference proceedings)
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Femtosecond transient absorption study of merocyanine J-aggregates Reviewed
Y. Hamanaka, H. Kurasawa, A. Nakamura, Y. Uchiyama, K. Marumoto, and S. Kuroda
Journal of Luminescence 94&95 451 - 455 2001.04
Language：English Publishing type：Research paper (scientific journal)
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Y. Hamanaka, J. Kuwabata, I. Tanahashi, S. Omi, and A. Nakamura
Physical Review B 63 104302 2001.04
Language：English Publishing type：Research paper (scientific journal)
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Primary processes of charge carrier generation in photoconducting polymers Reviewed
E. Farankevich, H. Ishii, Y. Hamanaka, T. Yokoyama, A. Fujii, S. Li, K. Yoshino, A. Nakamura, and K. Seki
Synthetic Metals 119 495 - 498 2001.04
Language：English Publishing type：Research paper (scientific journal)
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Electron energy relaxation dependent on size and matrix in gold-nanocrystal-dielectric composites Reviewed International journal
Y. Hamanaka, J. Kuwabata, A. Nakamura, I. Tanahashi, and S. Omi
Springer Series in Chemical Physics 66 401 - 403 2001
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
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Ultrafast relaxation dynamics of photoexcited carriers in an InGaAs/InP multiple quantum well Reviewed International journal
Y. Hamanaka, A. Nakamura, K. Tanase, R. Ohga, Y. Nonogaki, Y. Fujiwara, and Y. Takeda
Springer Proceedings in Physics 87 621 - 622 2001
Authorship：Lead author Language：English Publishing type：Research paper (international conference proceedings)
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Ultrafast electron relaxation via breathing vibration of gold nanocrystals embedded in a dielectric medium Reviewed
Y. Hamanaka, J. Kuwabata, I. Tanahashi, S. Omi, A. Nakamura
Physical Review B - Condensed Matter and Materials Physics 63 ( 10 ) 1043021 - 1043025 2001
Language：English Publishing type：Research paper (scientific journal)
Relaxation dynamics of electrons in gold nanocrystals with diameters of 3.0-17.5 nm embedded in SiO2, Al2O3, and TiO2 matrices have been investigated by means of femtosecond pump and probe spectroscopy. The experiments show that the energy relaxation rates depend on both the nanocrystal size and the matrix material. A model taking account of electron-breathing mode interaction, electron-bulk phonon interaction, and thermal diffusion through the interface can explain well the observed results. The breathing mode damping in the medium on a time scale of a few picoseconds plays an important role in the electron-energy dissipation process of the nanoscale composite system.
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Ultrafast relaxation dynamics of photoexcited carriers in an In0.53Ga0.47As/InP multiple-quantum well Reviewed
Y Hamanaka, A Nakamura, K Tanase, R Ohga, Y Nonogaki, Y Fujiwara, Y Takeda
PROCEEDINGS OF THE 25TH INTERNATIONAL CONFERENCE ON THE PHYSICS OF SEMICONDUCTORS, PTS I AND II 87 621 - 622 2001
Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPRINGER-VERLAG BERLIN
We heve investigated relaxation dynamics of photoexcited carriers and formation dynamics of excitons in a 10 nm-In0.53Ga0.47As/InP multiple quantum well at 77 X by femtosecond pump and probe spectroscopy. The observed spectral change of the exciton absorption band induced by the pump pulse is composed of broadening and bleaching components. The spectral broadening is attributed to scattering between excitons created by the probe pulse and free carriers generated by the pump pulse, and the bleaching is mainly due to the phase space filling. The time evolution of the absorption change shows that formation of excitons occurs on a time scale of similar to 20 ps after the intraband relaxation of photoexcited carriers.
