| Project/Area Number |
13450265
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
KONDO Ken-ichi Tokyo Institute of Technology, Materials and Structures Laboratory, Professor, 応用セラミックス研究所, 教授 (50111670)
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| Co-Investigator(Kenkyū-buntansha) |
HIRONAKA Yoichiro Materials and Structures Laboratory, Research Associate, 応用セラミックス研究所, 助手 (20293061)
G.NAKAMURA Kazutaka Materials and Structures Laboratory, Associate Professor, 応用セラミックス研究所, 助教授 (20302979)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥14,400,000 (Direct Cost: ¥14,400,000)
Fiscal Year 2002: ¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 2001: ¥8,300,000 (Direct Cost: ¥8,300,000)
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| Keywords | time-resolved X-ray diffraction / femtosecond laser / pulsed X-rays / pump and probe / dynamics / phase transition / レーザー吸収 / X線回折 / 時間分解測定 / シリコン / オージェ再結合 / プラズマ臨界密度 / 衝撃波 |
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| Research Abstract |
We investigated dynamics of a phase transition, which is induced by impulsive excitation, using a picosecond time-resolved X-ray diffraction technique. The pulsed X-rays were generated by focusing femtosecond laser beams onto metal targets at 10^17 W/cm^2 in a vacuum chamber, and extracted from a Be window. The X-rays were directed to a sample and the diffracted X-rays were detected by the L-N_2 cooled X-ray charge-coupled device. Time-resolved measurements were performed using a pump and probe technique. A 300-ps laser beam was irradiated on the sample at power density of 3.3 GW/cm^2 for excitation. The sample used was a silicon crystal (Si(111)). The time-resolved X-ray diffraction was obtained every 50 ps of time interval with a time-resolution of 10 ps. Lattice deformation corresponds to laser heating and acoustic-phonon propagation, which followed by the energy transfer from an electronic system to a lattice system, was directly observed. In order to increase the X-ray intensity at the sample position, an X-ray focusing system was constructed using a Johansson curved crystal. The X-rays were focused at a spot size with a diameter of 100・m and 400-times higher intensity. The newly constructed X-ray diffraction system can observe approximately 4 degrees at the spot.
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