Collective Structural Dynamics of Disordered Solids

9624436 Toulouse本项目采用拉曼光谱学和中子光谱学作为工具来研究眼镜中的网络拓扑结构。该研究将研究从高温到低温的光谱特征变化。特别令人感兴趣的是在较低温度下低频动力学的开始。此外，还将对最近几种液-玻璃跃迁理论的光谱预测进行测试。所研究的玻璃由于成分不同或由于施加的静水压力变化而具有不同的脆性参数。该项目将有助于更好地理解连接的、随机网络的拓扑结构与单个键的强度和振动动力学之间的关系。这项研究在本质上是基础性的，但由于非晶态和类玻璃材料的许多应用，其结果可能具有很大的实际意义。非晶固体或玻璃由于其复杂的网络结构而成为具有挑战性的研究对象。由于它们有许多商业用途，因此具有很大的实际意义。玻璃具有许多不同于有序晶体的性质。该项目将使用光谱技术来研究玻璃的低频振动特性，并将这些测量结果与材料的结构构象联系起来。由于玻璃的原子结构是在高温下形成的，而且由于玻璃是冷冻液体，因此从液体到玻璃状态的转变将作为温度的函数-从高温到低温。这将有助于更好地理解无序网络的振动动力学。这些结果应该普遍适用于其他更普遍的无序网络，如大脑或经济模型中开发的网络。＊＊＊

9624436 Toulouse This project employs Raman optical spectroscopy and neutron spectroscopy as tools for the study of network topologies in glasses. The research will study the variation of spectroscopic signatures from high temperatures to low temperatures. Of particular interest is the onset of low frequency dynamics at lower temperatures. In addition, tests will be made of the spectroscopic predictions of several recent theories of the liquid-glass transition. The glasses to be studied will have different fragility parameters because of composition or as a result of imposed variations in hydrostatic pressure. The project should lead to a better understanding of the relationship between the topology of connected, random networks, and the strength of individual bonds and vibrational dynamics. The research is fundamental in character but the results are potentially of great practical interest because of the many applications of amorphous and glass-like materials. %%% Amorphous solids or glasses are challenging objects for study because of their complex network structures. They are of great practical interest because of their many commercial applications. Glasses have many properties that differ from those of ordered crystals. This project will use spectroscopic techniques to study the low frequency vibrational properties of glasses and to relate these measurements to the structural conformation of the materials. Because the atomic structure of the glass is formed at high temperatures and because the glass is a frozen liquid, the transition from the liquid to the glass state will be followed as a function of temperature - from high temperature to low temperatures. This should lead to a better understanding of the vibrational dynamics of disordered networks. The results should have general applicability to other more general disordered networks such as the brain or as developed in economic models. ***