Structural Kinetics, a Novel Tool Using Gas Electron Diffraction With a Pulsed Electron Beam Synchronous With Photoexcitation

点击翻译按钮获取中文摘要

In this project in the Physical Chemistry Program of the Chemistry Division, Professors J. Ewbank and L. Schafer of the Chemistry Department of the University of Arkansas will continue the development and application of real-time gas electron diffraction (GED) using a pulsed electron beam synchronous with photoexcitation. The technique will be applied primarily to the study of the conformation and structure of short-lived chemical species, namely those in highly excited electronic states where the structure and conformation differ significantly from those in the ground and low-lying excited states, or species undergoing dynamical changes as the result of unimolecular reactions. Traditional GED has relied on the use of the photographic plate to record and store the information generated by the diffraction of electrons by molecules. This method was therefore limited to studying the structures of stable molecules. Current research in molecular dynamics concerns itself with how the structure and conformation of a molecular system evolves during a reaction process. Experimental information about such processes can only be obtained by means of techniques in which the time plays an essential role. The methods of pico- and femtosecond spectroscopy have been very successful in this regard but also have their limitations owing to the difficulty in interpreting often extremely complex spectral patterns. The method of real-time GED developed by the principal investigators has shown great promise in making important contribution to the understanding of the properties of short-lived species. The aim of this project is to capitalize on this potential and contribute to our understanding of the basic aspects of molecular dynamics.