Study on Acoustic Soft-Mode Dispersion by Impulsive Stimulated Brillouin Scattering
| Project/Area Number |
03452025
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Hokkaido University |
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Principal Investigator |
KINOSHITA Shuichi Hokkaido Univ., Res.Inst.Elec.Sci., Asso.Prof., 電子科学研究所, 助教授 (10112004)
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| Co-Investigator(Kenkyū-buntansha) |
KASAHARA Masaru Hokkaido Univ., Res.Inst.Elec.Sci., Res.Asso., 電子科学研究所, 助手 (30001697)
YAGI Toshirou Hokkaido Univ., Res.Inst.Elec.Sci., Prof., 電子科学研究所, 教授 (30002132)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥6,900,000 (Direct Cost: ¥6,900,000)
Fiscal Year 1992: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1991: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | Phonon / Stimulated Brillouin Scattering / Nonlinear Spectroscopy / Soft mode / Phase transition / Ferroelastics / 光誘起フォノン生成 / 音響フォノン / 表面音波 / 光カ-効果 / ソフトモ-ド |
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| Research Abstract |
We have developed a new phonon spectroscopy using impulsive stimulated Brillouin scattering. This method is based on the phonon generation by two crossing light pulses and the diffraction of a probe light by the phonon. Unlike recent measurements, we have employed a cw laser as a probe. This enables us to measure an extremely slow response near the phase transition point, indicating a high-resolution phonon spectroscopy in frequency regime. Furthermore, coherent nature of the generated phonons offers a measurement at extremely low phonon wave number. Combining with a spherical Fabry-Perot interferometer, we can perform directly the frequency-domain measurement for the generated non-equilibrium phonons. To confirm the advantage of this method, we have investigated the mechanisms of the phonon generation, the propagation of the generated phonon, the resonance effect on the phonon generation by the pulse train. Several applications have been performed, which include the generation of acoustic waves in liquids, metal surfaces, and liquid crystals. For the measurement of the acoustic soft-mode, we have employed a ferroelastic crystal KD_3(SeO_3)_2 as a sample, which is known to show a C_<66> soft phonon mode. We have performed the spatial intensity profile of the laser light transmitted through the crystal, which is influenced by the domain formation below the transition point. Particularly, the intesity of the refracted light at the domain wall gives a new observation method of the elastic fluctuation near the transition point. Indeed the refracted light at the domain wall is observable even above the transition point, suggesting the fluctuation of the domain formation takes place at those temperatures. Combining the ISBS experiment with the above transmission experiment, we have obtained the soft-mode behavior near the transition point. The detailed analysis of the result is now in progress.
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Report
(3 results)
Research Products
(9 results)
