Vibrational Spectroscopy and Dynamics of Reaction Intermediates

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

Marsha Lester of the University of Pennsylvania is supported by the Experimental Physical Chemistry Program to carry out a series of fundamental experimental studies of chemical reaction dynamics, many of which are based on chemical systems of significance in the atmosphere. The experiments utilize state-of-the-art spectroscopic and dynamical methods, but with the unique approach of initiating the studies from stabilized intermediates that lie along the reaction coordinate. Specifically, the planned studies focus on hydrogen trioxide, Cl-HCl, methyl trioxy, peroxymethyl nitrite, and HO-nitric acid intermediates. In each of these studies, fundamental or overtone excitation of a hydride stretch of the intermediate will provide sufficient energy to initiate dynamics on a reactive potential energy surface. Experimental observables include spectroscopic parameters that characterize the reaction intermediates in high detail, for example molecular structures, vibrational frequencies, and thresholds for dissociation and/or reaction. In addition, dynamical information will be obtained on intramolecular vibrational energy redistribution, dissociation and/or reaction dynamics, bond energies, and and enthalpies of formation of the intermediates. Experimental outcomes will be compared with theoretical calculations of the analogous properties derived from ab initio potential energy surfaces. In this project, young scientists at the undergraduate, graduate, and postdoctoral levels will participate in forefront scientific research, developing skills, experience, and confidence required to move into the scientific and technical workforce. The participants -- many of whom are women -- use technologically advanced laser equipment as they work on basic research projects, which are also relevant to broader issues in atmospheric chemistry.