Papers - Chiba, Ayano

Time-resolved small-angle x-ray scattering studies on the formation of Bacteria Cellulose

Ayano Chiba, Mikihito Takenaka, Yasuyuki Takahashi, Takeji Hashimoto

物性研究 (Bussei Kenkyu) 84 ( 6 ) 979-980 2005.09

Research paper (conference, symposium, etc.), Single Work

Dynamic structure of liquid chalcogens in the semiconductor-to-metal transition range

CHIBA AYANO, Makoto Yao, Yoshinori Ohmasa, Yusuke Hiejima, Yukinobu Kawakita, Stephen M. Bennington

Journal of Neutron Research 13 ( 1-3 ) 149-152 2005.03

Research paper (scientific journal), Joint Work, Accepted

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Dynamic structures of liquid Te 70 Se 30 and Te 50 Se 50 were investigated by inelastic neutron scattering experiments in the semiconductor-to-metal transition range. The bond-stretching modes for the both liquid mixtures were found to clearly soften when the transition occurs. We discuss the change of static and dynamic structures that accompany the transition.

X-ray Absorption and De-Excitation Processes of Krypton Clusters Studied by the XAFS-PEPICO Synchronous Measurements

K. Nagaya, A. Mori, H. Murakami, M. Yao, Y. Ohmasa, H. Kajikawa, K. Kobayashi, Y. Kajihara, A. Chiba, Y. Nishikawa, M. Ishii, Y. Fujii, E. Hayata

Physica Scripta T115   984 2005

Research paper (scientific journal), Joint Work, Accepted

パラジウムナノ微粒子の生成過程のその場観察

千葉 文野, Sivaniah Easan, 橋本 竹治

物性研究 83 ( 3 ) 329-330 2004.12

Research paper (scientific journal), Joint Work

Optic-type vibrational modes of liquid chalcoens

CHIBA AYANO, Yoshinori Ohmasa, Makoto Yao, Stephen M. Bennington

Journal of neutron research 12 ( 4 ) 301-304 2004.12

Research paper (scientific journal), Joint Work, Accepted

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We carried out inelastic neutron scattering measurements to study the dynamic structure of liquid Se and Te50Se50. The bond-stretching modes for both liquids were found to lie in higher energies than those forming a trigonal phase, showing that the chainlike molecules are more isolated than in the troigonal phase. The Q-dependence of the intensity of the dynamic structure factor was examined at the region of the stretching modes, and found to be explained by a simple model where we assumed completely out-of-phase motions of two atoms. The result shows the possibilities of extracting short-range structural information from such Q-dependences for these kinds of basically isolated molecules.

Dynamic structure of liquid Se, Te and Se-Te mixtures by neutron scattering measurements

CHIBA AYANO, Makoto Yao, Yoshinori Ohmasa, Jon Taylor, Stephen M. Bennington

AIP Conference Proceedings 708   436 2004.09

Research paper (scientific journal), Joint Work, Accepted

Vibrational, single-particle-like, and diffusive dynamics in liquid Se, Te, and Te50Se50

CHIBA AYANO, Yoshinori Ohmasa, and Makoto Yao

Journal of Chemical Physics 119 ( 17 ) 9047-9062 2003.11

Research paper (scientific journal), Joint Work, Accepted

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Neutron scattering measurements were carried out for liquid Se, liquid Te, and liquid Te50Se50. The results are discussed in the context of semiconductor-to-metal transition. As to liquid Te50Se50, the vibrational modes show a remarkable change when the semiconductor-to-metal transition occurs by temperature increase. A soft stretching mode was observed for the metallic phase and it shows the structural change; the appearance of long bonds in the metallic phase. The vibrational modes for liquid Se and liquid Te were obtained and agreed well with former works. The crossover from collective to single-particle-like regime was also observed for all liquid samples and the transition ranges (Q = 4.5–8 Å–1) are presented. The diffusive features in the low-Q region and single-particle-like properties in the high-Q region are discussed and are shown to be consistent with the results for the vibrational modes.

Neutron scattering studies of liquid tellurium–selenium mixtures

CHIBA AYANO, Yoshinori Ohmasaa, Yukinobu Kawakita, Makoto Yao and Hirohisa Endo

Journal of Non-Crystalline Solids 312-314   384-387 2002.10

Research paper (scientific journal), Joint Work, Accepted

Quasielastic Neutron Scattering of Liquid Te50Se50 in the Semiconductor-to-Metal Transition Range

CHIBA AYANO, Yoshinori Ohmasa, Makoto Yao, Oleg Petrenko and Yukinobu Kawakita

Journal of the Physical Society of Japan 71 ( 2 ) 504-509 2002.02

Research paper (scientific journal), Joint Work, Accepted

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We have carried out neutron scattering experiments for liquid Te50Se50 at 700 K (semiconducting regime), 900 K (transition regime) and 1100 K (metallic regime). The quasielastic scattering peak is comparatively narrow at the peak positions of S(Q). A remarkable increase in the peak width is observed near the first minimum of S(Q), when the semiconductor-to-metal transition occurs. Since the first peak of S(Q) in this system proves to mainly reflect the inter-chain correlation and the second peak to the intra-chain correlation, the observed broadening may suggest frequent bond-switching between the chains in the metallic regime.

Neutron Inelastic Scattering Measurements of Liquid Se2X2 (X: Halogen)

CHIBA AYANO, YUKINOBU KAWAKITA, YOSHINORI OHMASA, YUSUKE HIEJIMA, MAKOTO YAO

Analytical Sciences 17   i1089-i1092 2001

Research paper (scientific journal), Joint Work, Accepted

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We measured the vibrational spectra of liquid Se2Cl2 and Se2Br2 by neutron and Raman scattering. The spectra measured by each technique show roughly good agreements with earlier Raman works. A partial disagreement was observed for the neutron scattering data at the bond-bending mode of liquid Se2Br2. It is suggested that the disagreement might be attributed to the slightly dispersive behaviour of the mode. The generalized vibrational density of states, G(Q,E), for Se2Br2 obtained by neutron scatterings is reported to show the observed vibrational modes in the energy-momentum space.