Multidimensional and Nonlinear Kinetics in Complex Materials

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With support from the Chemical Measurement and Imaging program and co-funding from the Chemical Structures, Dynamics, and Mechanisms - A program, Professor Mark Berg and his group at the University of South Carolina are developing new methods for probing chemical changes that occur when a system is perturbed by illumination with powerful laser light. The research group is particularly interested in the response of a system to multiple perturbations, in contrast to more conventional approaches which use a single perturbation. These “multidimensional” experiments are uniquely useful for understanding complex materials where otherwise identical molecules may have their responses altered by their local environment. The research focuses on perturbing systems using ultrafast laser pulses then monitoring very fast responses (less than a trillionth of a second), enabling the elementary steps of a reaction to be observed before molecular motion reorganizes the local environment. Dr. Berg actively recruits undergraduates from both within and outside chemistry to provide a cross-disciplinary research experience. Graduate students are trained in advanced optics, spectroscopy, electronics and data-processing methods. Professor Berg is involved with workshops familiarizing students (especially those from underrepresented groups) with graduate school opportunities. He is also active in a partnership between the University and the Graduate Education for Minorities (GEM) Fellowship Program aimed at increasing the number of students from underrepresented groups who go on to graduate studies in STEM fields. As many liquids cool, they spontaneously form microstructures that lead to a very rapid increase in viscosity. Multidimensional spectroscopic experiments are designed to examine the initial formation of these microstructures to see if they are sufficient to explain the observed changes in macroscopic properties. Independent control of the polarization and phase of up to six laser pulses enables investigation of the local structure, fluidity and reaction dynamics in microstructures created by soaps and detergents. These microstructures range from simple micelles that solubilize organic materials in water to the complex bilayer membranes that are ubiquitous in cells. The Berg laboratory provides a highly interdisciplinary environment for graduate and undergraduate students involved in the research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.