Dynamics in Condensed Matter Systems

本文通过多时间尺度非线性实验研究了多种凝聚态体系的快速动力学以及动力学与局部结构的关系。所要检测的材料包括低温玻璃、靠近玻璃化转变的高温玻璃、玻璃形成液体和玻璃化转变，以及具有局部结构的液体，如液晶和聚合物熔体。为了组织目的，该提案分为三个小节：(A)凝聚态系统中的Psec振动光子回波；(B)低温玻璃、玻璃和玻璃跃迁附近液体的光学相干性研究；(C)复杂液体动力学：用Fsec瞬态光栅实验探测的玻璃形成液、聚合物熔体和液晶。(A)中的信息将提供：1)检查分子振动自由度与其动态环境相互作用的直接方法，以及2)对玻璃和液体动力学以及动态分子间相互作用的详细见解。在(B)中，绘制了液体和玻璃杯的波动率分布。实验检查均匀脱相和光谱扩散在广泛的温度和时间尺度。(C)小节包括对复杂液体动力学中局部结构作用的考察。实验的时间跨度从几十秒到几百秒甚至更长。使用基于激光的技术，本提案在微观水平上解决了一些关于动力学和结构相互作用的基本问题。所要检测的材料包括低温玻璃、靠近玻璃化转变的高温玻璃、玻璃形成液体和玻璃化转变，以及具有局部结构的液体，如液晶和聚合物熔体。待回答的问题如下。分子凝聚态系统的动力学发生在什么时间尺度上？介质的动力学如何影响嵌入分子的机械和电子自由度？局部结构如何决定发生在分子水平上的动力学性质？能量流入和流出分子的时间尺度和途径是什么？玻璃、液体和晶体性质的差异如何影响动力学过程？结构液体（如液晶、聚合物熔体和玻璃形成液体）中的动力学与简单液体中的动力学有何不同？

Abstract 9322504 Fayer This research examines fast dynamics and the relationship of dynamics to local structure in a variety of condensed matter systems using multiple time scale non-linear experiments. The materials to be examined include low temperature glasses, high temperature glasses near the glass transition, glass forming liquids and the glass transition, and liquids with local structure such as liquid crystals and polymer melts. The proposal is divided into three subsections for organizational purposes: (A) Psec Vibrational Photon Echoes in Condensed Matter Systems; (B) Optical Coherence Studies of Low Temperature Glasses and Glasses and Liquids Near the Glass Transition; and (C) Dynamics of Complex Liquids: Glass Forming Liquids, Polymer Melts, and Liquid Crystals Probed with Fsec Transient Grating Experiments. The information in (A) will provide: 1) a direct method for examining the interactions of a molecule's vibrational degrees of freedom with its dynamic environment, and 2) detailed insights into dynamics in glasses and liquids and dynamical intermolecular interactions. In (B), fluctuation rate distributions are mapped out for liquids and glasses. The experiments examine homogeneous dephasing and spectral diffusion over a wide range of temperatures and time scales. The subsection (C) includes examination of the role of local structure on the dynamics of complex liquids. The experiments span time scales of tens of fsec to hundreds of nsec and longer. %%% Using laser-based techniques, this proposal addresses a number of basic questions concerning the interplay of dynamics and structure at the microscopic level. The materials to be examined include low temperature glasses, high temperature glasses near the glass transition, glass forming liquids and the glass transition, and liquids with local structure such as liquid crystals and polymer melts. The questions to be answered are as follows. On what time scales do dynamics in molecular condensed matter systems occur? How do dynamics of a medium influence the mechanical and electronic degrees of freedom of an embedded molecule? How does local structure determine the nature of dynamics occurring on a molecular level? What are the time scales and pathways for the flow of energy into and out of molecules? How do differences in the nature of glasses, liquids, and crystals influence dynamical processes? How do dynamics in structured liquids, e. g., liquid crystals, in polymer melts, and in glass forming liquids differ from dynamics in simple liquids?