Photodissociation of Cyanoacetylene: Application to the Atmospheric Chemistry of Titan

The quantum yield and reaction threshold for the photochemical dissociation of cyanoacetylene into a hydrogen atom and the cyanoethynyl radical have been determined. The quantum yield at 185 nm is ∼0.09. The threshold is ∼240 nm. Combination of this data with literature values shows that production...

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Bibliographic Details
Published in:Icarus (New York, N.Y. 1962) N.Y. 1962), 1995-05, Vol.115 (1), p.119-125
Main Authors: Clarke, David W., Ferris, James P.
Format: Article
Language:English
Subjects:
Acetylene - analogs & derivatives
Acetylene - chemistry
Atmosphere
Cyanides - chemistry
Hydrocarbons - chemistry
Hydrogen - chemistry
Lunar And Planetary Exploration
Photochemistry
Photolysis
Saturn
Space life sciences
Spectrum Analysis
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Summary:The quantum yield and reaction threshold for the photochemical dissociation of cyanoacetylene into a hydrogen atom and the cyanoethynyl radical have been determined. The quantum yield at 185 nm is ∼0.09. The threshold is ∼240 nm. Combination of this data with literature values shows that production of excited-state cyanoacetylene is the major primary process resulting from irradiation between 185 and 254 nm. Also determined are the relative rate constants for the abstraction of a hydrogen atom from hydrogen, methane, and ethane by the cyanoethynyl radical (k(H2):k(CH4):k(C2H6) = 1:9.3:63). Implications of these results for the proposal that hydrogen abstraction plays an important role in the conversion of methane to ethane and in the protection of unsaturated compounds from photoconsumption in the atmosphere of Titan are discussed.
ISSN:0019-1035
1090-2643
DOI:10.1006/icar.1995.1083