| Project/Area Number |
12555009
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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 | 展開研究 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TANAKA Hajime Institute of Industrial Science, Professor, 生産技術研究所, 教授 (60159019)
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| Co-Investigator(Kenkyū-buntansha) |
OOKUBO Yuusei JASCO Corporation, Applied technology section, reseacher, 第一技術部・応用技術課, 技術2係係長(研究職)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥13,300,000 (Direct Cost: ¥13,300,000)
Fiscal Year 2002: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2001: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥7,800,000 (Direct Cost: ¥7,800,000)
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| Keywords | Phase-coherent light scattering method / light grating / mode selective excitation / Dynamics of fluctuation / liquid crystal isotropic phase / complex spectrum / Critical phenomena of specific heat / frequency-tunable CW laser / モード選択 / 熱拡散モードRayleighスペクトル |
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| Research Abstract |
We developed a new method of dynamic light scattering, which enables us to make 'mode-selective' measurement of Rayleigh-Brillouin scattering in liquids. Different from the conventional light scattering methods, which measure the power spectrum of light scattered by spontaneously excited fluctuations, we generate a coherent grating by using a laser-induced scanning interference pattern and measure complex spectra of a light-excited mode by its phase-sensitive superheterodyne detection. The mode-selectivity of our phase-coherent light scattering method is a unique feature, which cannot be realized by the conventional light scattering methods measuring the power spectrum of light scattered by spontaneously excited fluctuations. This is particularly useful to study the mode usually hidden behind large fluctuations of another mode. For example, we can control the amplitude of the temperature grating by changing the absorption coefficient of a liquid by adding a small amount of dye molecules. This controllability of the signal intensity and the resulting mode selectivity allow us to pick up only a thermal diffusion mode even under the existence of other incoherent modes with large amplitude. To demonstrate the capability of our method, we study a thermal diffusion of liquid crystals in isotropic phase ; in conventional methods in frequency domain, the spectra of thermal diffusion mode are usually hidden behind ones of orientational relaxation mode near its phase-transition point. Using our method, we found sudden decreases in both spectral amplitudes and linewidths near a transition point, which we regard as the reflection of the singular behavior of the specific heat and the thermal diffusivity, respectively. This is the first measurement of the thermal singularity near the phase-transition point of liquid crystalline sample in isotropic phase by using dynamic light scattering methods.
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