Development of a new experimental system for hypersonic relaxation study

我们在过去几年的研究已经产生了一种新的超声光散射技术，它有助于通过测量超高频范围内的超声速度和吸收来研究分子和/或分子缔合的动态性质。本研究的目的集中在该技术(高分辨率布拉格反射技术)在软材料中的超声弛豫研究领域中的更广泛分布上，这通常由物理学家进行，在过去的三年里取得的主要成果是：(1)超声光谱的可用频率范围被扩展到2 GHz以上，具有足够的分辨率和精度。(2)高分辨率布拉格反射技术被进一步发展为观察高能声子的高分辨率布里渊散射光谱。(3)新建立的技术被应用于研究线虫(在一定温度下形成向列相-液晶相的分子)的分子重定向运动。在这些结果的基础上，我们继续深入研究更宽的频率范围。

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.