Berg is supported by the Experimental Physical Chemistry Program to study fundamental problems in liquid and glass dynamics using a combined experimental/theoretical approach. The broad viscosity range available in supercooled liquids will be utilized for exploring the origin and temporal development of dynamical features within the 50 femtosecond to 25 nanosecond window accessible to ultrafast laser methods. Femtosecond techniques and related theory will be employed for studies that include probes of intertial and diffusive dynamics, the development of dynamic inhomogeneity near the liquid-glass transition, and whether liquid dynamics can be described in terms of `modes.` An essential feature of this project is the comparison of different dynamical measurements within the same system. The outcomes from this research are expected to contribute understanding useful in developing a comprehensive molecular theory of the collective dynamics of liquids and glasses. Many technologically important processes are influenced by the dynamics of simple liquids or other disordered materials. For example, materials such as polymers, inorganic glasses, and biological materials are used or processed in a fully or partially fluid state. New insights into the nature of supercooled liquids and the liquid-glass transition that will result from this project could impact materials design and processing technologies.
