Prelude to Hot Chemistry: Preliminary Studies on the Collisional Dynamics of Highly Vibrationally Excited Molecules

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Dr. Amy Mullin of Boston University is supported by the Experimental Physical Chemistry Program of the Chemistry Division with a Research Planning Grant to study the collisional and reactive dynamics of highly vibrationally excited polyatomic molecules. These species will be prepared by ultraviolet laser excitation followed by rapid internal conversion to high vibrational levels of the ground electronic state. Preliminary studies will concentrate on energy transfer between vibrationally excited pyrazine or pyridine with carbon dioxide and water. Product state distributions and absolute cross sections will be measured. Ultimately, experiments will be conducted to investigate the ability of high levels of internal excitation to drive otherwise unreactive systems over an activation barrier. Most chemical reactions take place on the ground electronic states of the reactants. Large activation barriers can prevent reactions from taking place, even when the systems are at elevated temperatures. In this project, Professor Mullin will use laser excitation to populate high vibrational levels of these molecules, corresponding to vibrational temperatures of 3000K, a temperature which would normally decompose the molecule. This method of preparation allows a large amount of energy to be present in the reactant without decomposing it and enhances the reaction by providing enough energy to overcome the activation barrier.