Dynamics of Pressure-Dependent Atmospheric Reactions

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

This study involves the use of computational methods to investigate a potentially important pathway for association reactions, being those chemical reactions in which two species combine to form a metastable intermediate species before dissociating to the final products. The potential pathways involve the ways in which excess energy is transferred to the bath gas. The standard Energy Transfer Mechanism (ETM) has been employed successfully to explain a number of atmospherically important association reactions. The alternative process is the Chaperone Mechanism (CM) that could explain why some association reactions have multiple channels or unusual dependence on concentrations of non-reacting species (for example, water vapor). A detailed framework for dealing with the CM component of association reactions will be developed, and an investigation of the utility of using the rate of quenching of vibrationally excited species as an alternative to using the high pressure limiting association rate coefficient will also be undertaken. Finally, a computer program will be developed that incorporates the key findings of this study and will be freely distributed to all interested parties. The results of this research, while relevant to atmospheric chemistry, will also benefit researchers studying combustion, planetary atmospheres, and other chemically reacting systems.