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. ***
