Dynamics of condensed matter systems

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My research concentrates on the time evolution of microstructures. Since the microstructure depends on the history of the sample it requires nonequilibrium thermodynamics for its understanding. The microstructure of a material is central to most of its physical and mechanical properties. Not only failure rates, but many other important properties including tensile strength, chemical reactivity and magnetic coercivity, depend crucially on this morphology. The typical length scales of these structures is micrometers. It is an important fundamental problem in physics to understand how microstructures arise, how to characterize them and how they evolve in time. Disordered and nonequilibrium systems span the range of materials including binary alloys (Ni_3Al used for jet turbines) to directionally solidifying crystals (snowflakes). The nature and role of coherence and correlations in disordered systems is still not fully understood. Real-time in-situ x-ray measurements, using either time resolved diffraction or x-ray photon correlation spectroscopy, allow measurements of the microstructure under conditions similar to the conditions used in processing the materials. They are thus ideally suited to study the time evolution of microstructure. My research has a two main areas of development. The first is to develop better instrumentation and techniques for in-situ time-resolved x-ray scattering to help address these issues. It is my opinion is that one of the largest impacts of physics has been to develop the instrumentation used by the rest of science. In order to pursue this objective, I am involved in designing and building instrumentation to use the brightest x-ray synchrotron sources and the new x-ray laser at SLAC. The second focus is to understand the physics described above by performing x-ray experiments on materials where microstructure plays an important role.