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[20.05] Chemical Growth Processes in Titan's Atmosphere: Theoretical Rates and Product Distributions for Reactions between C₂H and R₁R₂C=CR₃R₄ Species

D. E. Woon, J.-Y. Park (Molecular Research Institute)

The ethynyl radical (C₂H) can attack unsaturated carbon-carbon bonds with no activation barrier, making such reactions very favorable under the low temperature and pressure conditions in Titan's upper atmosphere, where tholin production generates the satellite's distinctive haze layers. We have used density functional theory to characterize reactions between C₂H and R₁R₂C=CR₃R₄ species ranging from ethylene to tetramethyl ethylene. Outcomes include multi-channel addition-elimination reactions and H abstraction. We will discuss trends in the reaction rates and product distributions as a function of temperature and pressure. Support for this work by the NASA Planetary Atmospheres program (grant NAG5-12305) is gratefully acknowledged.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.