Experimental Studies of the Liquid-Glass Transition

9980370 Cummins该项目通过激光散射光谱法研究了液体-玻璃转变附近的液体和固体玻璃的动力学。最近的理论和实验研究表明，弛豫（或记忆）功能在过冷液体中表现出复杂的行为，在几十年的频率延伸。目前的研究旨在测量这些功能及其随温度降低的演变。数据分析将利用模式耦合理论（MCT）的扩展，该理论现在包括取向自由度。将进行一个系统的调查，极化和去极化布里渊散射的分子玻璃前salol探索在何种程度上可以确定可靠的弛豫函数与这种技术。它们将被用来评估这些结果与MCT的兼容性，MCT提供了密度相关函数及其随温度的演变的详细预测。此外，在较低的温度下，老化现象和两个时间标度行为的玻璃的动力学已在理论上预测，并在计算机模拟中观察到将被追求。开发的技术也将应用于新材料，包括弹性体，其中液体和玻璃相被中间弹性体（或橡胶）相分离的材料。液态玻璃化转变是凝聚态物理学中最古老的未解决的基本问题之一。它在各种玻璃包括塑料和玻璃金属合金的制造中也是主要的实际关注点。电流模式耦合理论将进行测试，以评估在何种程度上可以确定可靠的松弛（或记忆）功能与这种技术。此外，在较低的温度下，老化现象和两个时间标度行为的玻璃的动力学已在理论上预测，并在计算机模拟中观察到将被追求。该技术还将应用于新材料，包括弹性体，其中液体和玻璃相被中间弹性体（或橡胶）相分离的材料。本研究项目利用激光光散射技术，主要由研究生和博士后研究人员进行。该计划将包括与美国和欧洲的其他研究小组的合作。

9980370CumminsThis project investigates the dynamics of liquids in the vicinity of the liquid-glass transition and of solid glasses by laser light scattering spectroscopy. Recent theoretical and experimental research has shown that relaxation (or memory) functions in supercooled liquids exhibit complex behavior extending over many decades in frequency. Current research is directed at measuring these functions and their evolution with decreasing temperature. The data analysis will utilize an extension of mode coupling theory (MCT) that now includes orientational degrees of freedom. A systemic investigation of both polarized and depolarized Brillouin scattering in the molecular glass-former salol will be carried out to explore the extent to which relaxation functions can be determined reliably with this technique. They will be used to assess the compatibility of such results with MCT, which provides detailed predictions for density correlation functions and their evolution with temperature. In addition, the dynamics of glasses at lower temperatures where aging phenomena and two-time scaling behavior has been predicted theoretically and observed in computer simulations will be pursued. The techniques developed will also be applied to new materials including elastomers, materials in which the liquid and glass phases are separated by an intermediate elastomer (or rubber) phase.%%%The liquid-glass transition is one of the oldest unresolved fundamental problems in condensed matter physics. It is also of major practical concern in the manufacture of various glasses including plastics and glassy metallic alloys. Current mode coupling theories will be tested to assess the extent to which relaxation (or memory) functions can be determined reliably with this technique. In addition, the dynamics of glasses at lower temperatures where aging phenomena and two-time scaling behavior has been predicted theoretically and observed in computer simulations will be pursued. The techniques developed will also be applied to new materials including elastomers, materials in which the liquid and glass phases are separated by an intermediate elastomer (or rubber) phase.This research project utilizes laser light-scattering techniques and will be conducted by primarily by graduate students and postdoctoral researchers. The program will include collaborations with other research groups both in the US and in Europe.***