Simultaneous Measurements of Ultrafast Motions of Electrons and Atoms at SPring-8 – Guidelines for Development of Materials for Ultrafast Optical Recording Medium – (Press Release)
- Release Date
- 06 Jan, 2010
- BL40XU (High Flux)
Japan Synchrotron Radiation Research Institute
Japan Science and Technology Agency
RIKEN
University of Tsukuba
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Japan Synchrotron Radiation Research Institute (JASRI; Tetsuhisa Shirakawa, President), Japan Science and Technology Agency (JST; Koichi Kitazawa, President), RIKEN (Ryoji Noyori, President) and the University of Tsukuba (Nobuhiro Yamada, President) succeeded in the simultaneous measurements of the ultrafast motions of electrons and atoms using the high-luminance X-ray at SPring-8. Up to now, the correlation between the motion of electrons and that of atoms has not been determined accurately because different researchers have measured the motions of electrons and atoms separately using different samples. In this study, the research group used a new measurement method and found that the motion of electrons changes the atomic distance uniformly within a ten-billionth of a second in Co-Fe cyanides*2 showing a photoinduced phase transition.*1 If the correlation between the ultrafast motion of electrons due to photoexcitation and the uniform ultrafast motion of atoms is clarified by this new method in the future, the mechanism of optical recording will be clarified, which will provide guidelines for improving its speed and efficiency. Optical recording is utilized in practical devices such as CD and DVD recorders. This new measurement system will greatly contribute to the improvement of their performance. Under the research theme "X-ray Pinpoint Structural Measurement of Reaction Phenomena" (leader: Masaki Takata, chief scientist of RIKEN) in the research area "Novel Measuring and Analytical Technology Contributions to the Elucidation and Application of Materials" (research supervisor: Michiyoshi Tanaka, professor emeritus at Tohoku University) supported by the Core Research for Evolutional Science and Technology (CREST) program of JST, a joint research group consisting of Masaki Takata, Shigeru Kimura (vice-chief scientist of JASRI) and Yutaka Moritomo (professor at University of Tsukuba) achieved the above results. The achievements will be published in the journal of The Japan Society of Applied Physics, Applied Physics Express (online version), on 8 January 2010. Publication: |
<Figure>
Fig. 1 Schematic of Co-Fe cyanides. The red balls indicate cobalt ions and the blue balls indicate iron ions.
Fig. 2 (a) Method of generating "excitation light" and "light to observe electrons."
(b) Configuration of "excitation light," "light to observe electrons," and "light to observe atoms."
Fig. 3 Delay time dependence of diffraction pattern.
Fig. 4 Delay time dependence of change in atomic distance (top)
and number of electrons moved (bottom).
<Glossary>
*1 Photoinduced phase transition
A process in which light irradiation on a material induces atom displacement and the phase of the material changes to another.
*2 Co-Fe cyanides
Compounds in which cobalt ions and iron ions are bridged by a cyano group. They show the interesting property of becoming magnetic under low-temperature light irradiation.
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