Multidimensional Methods for Kinetics in Complex Materials

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With support from the Chemical Measurement and Imaging program in the Division of Chemistry, Professor Mark Berg of the University of South Carolina is developing and applying new laser based methods for measuring very fast chemical reactions in complex materials such as polymers and ionic liquids. Traditional methods use a laser pulse to perturb a chemical system once and then follow the reaction over a single time period. The new methods developed in this project will use multiple perturbations separated by carefully chosen time intervals. This approach should allow for the observation of specific types of molecules or reactions within a complex mixture, for example the collisions of light-excited molecules in photoactive materials.This project will expand the range of processes and time scales where these methods can be applied and thereby allow their application to a wider range of problems. Specific targets include: How does a homogeneous, small-molecule solvent become heterogeneous as the molecule polymerizes? Do different molecule-sized sites occur in an ionic liquid, and do these sites alter the progress of reactions that use ionic liquids as the solvent? What is the range of travel for an optical excitation in a conjugated polymer, and how do the resulting collisions quench captured energy? Professor Berg is active in a university-wide initiative to increase applications to graduate school by underrepresented groups. He is also participating in an NSF-funded IGERT program aimed at developing interdisciplinary training programs at the University of South Carolina.