Development of a new experimental system for hypersonic relaxation study

我们在过去几年的研究中提出了一种新的超声光散射技术，该技术通过测量超高频范围内的超声速度和吸收来研究分子和/或分子间的动态特性。目前研究的目的是将这种技术（高分辨率布拉格反射技术）广泛应用于软材料的超声松弛研究领域，这些研究通常由物理学家、化学家和生物学家进行。三年来取得的主要成果有：(1)超声光谱的可用频率范围扩大到2 GHz以上，具有足够的分辨率和精度。(2)将高分辨率布拉格反射技术进一步发展为观测高能声子的高分辨率光谱布里渊散射实验。(3)将新建立的技术应用于线虫（在一定温度下形成向列-液晶相的分子）的分子重定向运动的研究。在这些结果的基础上，我们正在继续深入研究更广泛的频率范围。

Our previous study in the past few years had yielded a new ultrasonic light scattering technique which is useful for investigating dynamic properties of molecules and/or molecular associations through the measurement of ultrasonic velocity and absorption in ultra-high frequency range. The aim of the present research has been focused onto a wider distribution of this technique (high-resolution Bragg reflection technique) over the field of ultrasonic relaxation studies in soft materials, which are commonly conducted by physicists, chemists and biologists.The major results accomplished during the past three years are :(1) Available frequency range of ultrasonic spectroscopy was expanded over 2 GHz with sufficient resolution and accuracy.(2) The high-resolution Bragg reflection technique was further developed into a high-resolution spectroscopy of Brillouin scattering experiment for observing high energy phonons.(3) The newly established technique was applied for the study of molecular reorientational motion of nematogen (molecules which form nematic-liquid crystal phase below a certain temperature).On the basis of these results, we are continuing an intensive study for even wider frequency range.