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Journal Articles

Neutron spin-echo studies of the structural relaxation of network liquid ZnCl$$_2$$ at the structure factor primary peak and prepeak

Luo, P.*; Zhai, Y.*; Leao, J. B.*; Kofu, Maiko; Nakajima, Kenji; Faraone, A.*; Zhang, Y.*

Journal of Physical Chemistry Letters (Internet), 12(1), p.392 - 398, 2021/01

Using neutron spin-echo spectroscopy, we studied the microscopic structural relaxation of a prototypical network ionic liquid ZnCl$$_2$$ at the structure factor primary peak and prepeak. The results show that the relaxation at the primary peak is faster than the prepeak and that the activation energy is $$sim 33$$% higher. A stretched exponential relaxation is observed even at temperatures well-above the melting point $$T_{rm m}$$. Surprisingly, the stretching exponent shows a rapid increase upon cooling, especially at the primary peak, where it changes from a stretched exponential to a simple exponential on approaching the $$T_{rm m}$$. These results suggest that the appearance of glassy dynamics typical of the supercooled state even in the equilibrium liquid state of ZnCl$$_2$$ as well as the difference of activation energy at the two investigated length scales are related to the formation of a network structure on cooling.

Journal Articles

Dynamics of atomic hydrogen in palladium probed by neutron spectroscopy

Kofu, Maiko; Yamamuro, Osamu*

Journal of the Physical Society of Japan, 89(5), p.051002_1 - 051002_12, 2020/05

 Times Cited Count:1 Percentile:37.87(Physics, Multidisciplinary)

The behavior of hydrogen in metals has attracted much attention in fundamental and applied research areas for many decades. Among metals, palladium is remarkable in that it can absorb large quantities of hydrogen, and hydrogen atoms are highly mobile in the fcc Pd lattice. The dynamics of hydrogen in Pd have been investigated by means of neutron spectroscopy which is the best tool to provide insights into microscopic dynamics of hydrogen atoms. In this article, we review recent and historical neutron scattering works to facilitate the latest understanding of the hydrogen dynamics in bulk and nanometer-sized Pd hydrides.

Journal Articles

Experimental investigation of the suppressed superconducting gap and double-resonance mode in Ba$$_{1-x}$$K$$_{x}$$Fe$$_{2}$$As$$_{2}$$

Ideta, Shinichiro*; Murai, Naoki; Nakajima, Masamichi*; Kajimoto, Ryoichi; Tanaka, Kiyohisa*

Physical Review B, 100(23), p.235135_1 - 235135_7, 2019/12

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

Journal Articles

Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators Sb$$_{2-x}$$V$$_{x}$$Te$$_{3}$$

Sumida, Kazuki*; Kakoki, Masaaki*; Reimann, J.*; Nurmamat, M.*; Goto, Shinichi*; Takeda, Yukiharu; Saito, Yuji; Kokh, K. A.*; Tereshchenko, O. E.*; G$"u$dde, J.*; et al.

New Journal of Physics (Internet), 21(9), p.093006_1 - 093006_8, 2019/09

 Times Cited Count:3 Percentile:52.32(Physics, Multidisciplinary)

Journal Articles

Mass transport in the PdCu phase structures during hydrogen adsorption and absorption studied by XPS under hydrogen atmosphere

Tang, J.*; Yamamoto, Susumu*; Koitaya, Takanori*; Yoshigoe, Akitaka; Tokunaga, Takuma*; Mukai, Kozo*; Matsuda, Iwao*; Yoshinobu, Jun*

Applied Surface Science, 480, p.419 - 426, 2019/06

 Times Cited Count:1 Percentile:81.58(Chemistry, Physical)

Mass transports during hydrogen adsorption and absorption processes of PdCu alloys that has advantages of higher hydrogen diffusivity and economically lower-cost than the other Pd-alloys were studied. The research was made with a comparison of the well-known ordered phase of the bcc structure (the B2 phase) and a mixed phase of the fcc and B2 structures. ${it In-situ}$ ultrahigh vacuum X-ray photoelectron spectroscopy and ambient pressure X-ray photoelectron spectroscopy using synchrotron radiation were carried out to trace the chemical states of the Pd and Cu atoms as a function of temperatures. It is elucidated that the initial adsorption and absorption processes were similar in the two phases, but a hydrogen diffusion rate to the bulk was higher in the ordered phase than in the mixed one. We found the dynamics of the Pd and Cu atoms during the hydrogen adsorption/absorption processes largely depend on temperature. In the hydrogen atmosphere, the Pd atoms segregate at the surface below 373 K and Cu atoms segregate at the surface above 373 K. The present results agree well with the previous theoretical calculations and, thus, provide appropriate inputs toward developments of the hydrogen permeation materials.

Journal Articles

Anomaly of structural relaxation in complex liquid metal of bismuth; Dynamic correlation function of coherent quasi-elastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

Physica B; Condensed Matter, 551, p.291 - 296, 2018/12

 Times Cited Count:7 Percentile:43.14(Physics, Condensed Matter)

There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.

Journal Articles

Effect of electron correlations on spin excitation bandwidth in Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$ as seen via time-of-flight inelastic neutron scattering

Murai, Naoki; Suzuki, Katsuhiro*; Ideta, Shinichiro*; Nakajima, Masamichi*; Tanaka, Kiyohisa*; Ikeda, Hiroaki*; Kajimoto, Ryoichi

Physical Review B, 97(24), p.241112_1 - 241112_6, 2018/06

 Times Cited Count:4 Percentile:59.06(Materials Science, Multidisciplinary)

We use inelastic neutron scattering (INS) to investigate the effect of electron correlations on spin dynamics in iron-based superconductor Ba$$_{0.75}$$K$$_{0.25}$$Fe$$_{2}$$As$$_{2}$$. Our INS data show a spin-wave-like dispersive feature, with a zone boundary energy of 200 meV. A first principles analysis of dynamical spin susceptibility, incorporating the mass renormalization factor of 3, as determined by angle-resolved photoemission spectroscopy, provides a reasonable description of the observed spin excitations. This analysis shows that electron correlations in the Fe-3d bands yield enhanced effective electron masses, and consequently, induce substantial narrowing of the spin excitation bandwidth. Our results highlight the importance of electron correlations in an itinerant description of the spin excitations in iron-based superconductors.

Journal Articles

Difference in the hydration water mobility around F-actin and myosin subfragment-1 studied by quasielastic neutron scattering

Matsuo, Tatsuhito; Arata, Toshiaki*; Oda, Toshiro*; Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Fujiwara, Satoru

Biochemistry and Biophysics Reports (Internet), 6, p.220 - 225, 2016/07

Journal Articles

Preface to topical papers on frontier of pulsed electron beam for research on photoexcited dynamics

Itakura, Ryuji

Reza Kenkyu, 43(3), p.136 - 137, 2015/03

Recently, technique of pulsed electron beam generation combined with ultrafast laser technology has been developed for realization of time-resolved measurements. A variety of methods such as an electron gun with a photo-cathode and an optical gating of a CW electron beam are proposed and demonstrated. We will compiles topical papers on frontier of pulsed electron beam for research on photoexcited dynamics in one volume of "The Review of Laser Engineering". This paper is a preface for describing the aim and contents of this special volume.

Journal Articles

${{it In situ}}$ synchrotron radiation photoelectron spectroscopy study of the oxidation of the Ge(100)-2$$times$$1 surface by supersonic molecular oxygen beams

Yoshigoe, Akitaka; Teraoka, Yuden; Okada, Ryuta; Yamada, Yoichi*; Sasaki, Masahiro*

Journal of Chemical Physics, 141(17), p.174708_1 - 174708_7, 2014/11

 Times Cited Count:8 Percentile:61.94(Chemistry, Physical)

${{it In situ}}$ synchrotron radiation photoelectron spectroscopy was performed during the oxidation of the Ge(100)-2$$times$$1 surface induced by a molecular oxygen beam with various incident energies up to 2.2 eV from the initial to saturation coverage of surface oxides. The saturation coverage of oxygen on the clean Ge(100) surface was much lower than one monolayer and the oxidation state of Ge was +2 at most. This indicates that the Ge(100) surface is in strong contrast to Si surfaces. The direct adsorption process can be activated by increasing the translational energy, resulting in an increased population of Ge$$^{2+}$$ and a higher final oxygen coverage. Our findings will contribute to the fundamental understanding of oxygen adsorption processes at 300 K from the initial stages to saturated oxidation.

Journal Articles

Direct numerical simulations for non-equilibrium superconducting dynamics and related neutron detection in MgB$$_{2}$$

Machida, Masahiko; Koyama, Tomio*; Kato, Masaru*; Ishida, Takekazu*

Physica C, 426-431(1), p.169 - 173, 2005/10

no abstracts in English

Journal Articles

Quantum-classical wave packet calculations for the O($$^{1}$$D)+N$$_{2}$$O$$rightarrow$$NO+NO/N$$_{2}$$+O$$_{2}$$ reaction

Takayanagi, Toshiyuki

Chemical Physics, 308(3), p.211 - 216, 2005/01

 Times Cited Count:6 Percentile:78.09(Chemistry, Physical)

no abstracts in English

Journal Articles

Large-scale simulations on bubbly flow dynamics in a fuel channel with the earth simulator

Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*

Hai Pafomansu Komputingu To Keisan Kagaku Shimpojium (HPCS 2005) Rombunshu, P. 16, 2005/01

no abstracts in English

Journal Articles

Theoretical simulations of dynamics of excess electron attachment to acetonitrile clusters

Takayanagi, Toshiyuki

Chemical Physics, 302(1-3), p.85 - 93, 2004/07

 Times Cited Count:10 Percentile:66.64(Chemistry, Physical)

no abstracts in English

Journal Articles

Theoretical study on photoexcitation dynamics of the K atom attached to helium clusters and the solvation structures of K*He$$_{n}$$ exciplexes

Takayanagi, Toshiyuki; Shiga, Motoyuki

Physical Chemistry Chemical Physics, 6(13), p.3241 - 3247, 2004/07

 Times Cited Count:28 Percentile:30.76(Chemistry, Physical)

no abstracts in English

Journal Articles

Exit interaction effect on nascent product state distribution of O($$^{1}$$D)+N$$_{2}$$O$$rightarrow$$NO+NO

Kawai, Shinnosuke*; Fujimura, Yo*; Kajimoto, Okitsugu*; Takayanagi, Toshiyuki

Journal of Chemical Physics, 120(14), p.6430 - 6438, 2004/04

 Times Cited Count:8 Percentile:73.04(Chemistry, Physical)

no abstracts in English

Journal Articles

Program for tests on magnetic bearing suspended roter dynamics for Gas Turbine High Temperature Reactor (GTHTR300)

Takada, Shoji; Takizuka, Takakazu; Kunitomi, Kazuhiko; Kosugiyama, Shinichi; Yan, X.; Matsumoto, Iwao*

Nippon Genshiryoku Gakkai Wabun Rombunshi, 2(4), p.525 - 531, 2003/12

no abstracts in English

Journal Articles

Hydration in proteins observed by high-resolution neutron crystallography

Chatake, Toshiyuki; Ostermann, A.; Kurihara, Kazuo; Parak, F.*; Niimura, Nobuo

Proteins: Structure, Function, and Bioinformatics, 50(3), p.516 - 523, 2003/02

no abstracts in English

Journal Articles

Protein dynamics studied by molecular simulation and neutron scattering

Kitao, Akio

Hamon, 12(2), p.80 - 83, 2002/04

no abstracts in English

Journal Articles

A Quantum reactive scattering study of the spin-forbidden CH(X$$^{2}Pi$$)+N$$_{2}$$(X$$^{1}Sigma_{g}^{+}$$)$$rightarrow $$HCN(X$$^{1}Sigma^{+}$$)+N($$^{4}$$S) reaction

Wada, Akira; Takayanagi, Toshiyuki

Journal of Chemical Physics, 116(16), p.7065 - 7072, 2002/04

 Times Cited Count:10 Percentile:68.06(Chemistry, Physical)

no abstracts in English

75 (Records 1-20 displayed on this page)