A Gas-Phase Kinetic Study of the N(2D) + CH3CCH and N(2D) + CH3CN Reactions

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Autori principali: Hickson, Kevin M., Loison, Jean-Christophe, Benne, Benjamin, Dobrijevic, Michel
Natura: Preprint
Pubblicazione: 2025
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author Hickson, Kevin M.
Loison, Jean-Christophe
Benne, Benjamin
Dobrijevic, Michel
author_facet Hickson, Kevin M.
Loison, Jean-Christophe
Benne, Benjamin
Dobrijevic, Michel
contents The chemistry of planetary atmospheres containing molecular nitrogen as a major atmospheric component is strongly influenced by the reactions of atomic nitrogen. Although nitrogen atoms in their ground electronic state N(4S) are mostly unreactive towards stable molecules, electronically excited nitrogen atoms N(2D) are much more reactive and could play an important role in the formation of nitriles and other nitrogen bearing organic molecules in planetary atmospheres such as Titan. Despite this, few kinetic studies of N(2D) reactions have been performed over the appropriate low temperature range. Here, we report the results of an experimental study of the reactions N(2D) + methylacetylene, CH3CCH, and N(2D) + acetonitrile, CH3CN, using a supersonic flow reactor at selected temperatures between 50 K and 296 K. N(2D) atoms, which were generated indirectly as a product of the C(3P) + NO reaction, were subsequently detected by laser induced fluorescence in the vacuum ultraviolet wavelength region. The measured rate constants are significantly larger than the estimated values in current photochemical models and do not display large variations as a function of temperature. The new rate constants are included in a 1D coupled ion-neutral model of Titans atmosphere to test their influence on the simulated species abundances. In addition, the overall description of both reactions is improved by considering the results of recent experimental and theoretical work examining the product channels of these processes. These simulations indicate that while the N(2D) + CH3CCH reaction has only a limited overall influence on Titans atmospheric chemistry, the N(2D) + CH3CN reaction could lead to the formation of significant relative abundances of cyanomethamine, HNCHCN, in the upper atmosphere.
format Preprint
id arxiv_https___arxiv_org_abs_2511_06941
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A Gas-Phase Kinetic Study of the N(2D) + CH3CCH and N(2D) + CH3CN Reactions
Hickson, Kevin M.
Loison, Jean-Christophe
Benne, Benjamin
Dobrijevic, Michel
Earth and Planetary Astrophysics
Astrophysics of Galaxies
The chemistry of planetary atmospheres containing molecular nitrogen as a major atmospheric component is strongly influenced by the reactions of atomic nitrogen. Although nitrogen atoms in their ground electronic state N(4S) are mostly unreactive towards stable molecules, electronically excited nitrogen atoms N(2D) are much more reactive and could play an important role in the formation of nitriles and other nitrogen bearing organic molecules in planetary atmospheres such as Titan. Despite this, few kinetic studies of N(2D) reactions have been performed over the appropriate low temperature range. Here, we report the results of an experimental study of the reactions N(2D) + methylacetylene, CH3CCH, and N(2D) + acetonitrile, CH3CN, using a supersonic flow reactor at selected temperatures between 50 K and 296 K. N(2D) atoms, which were generated indirectly as a product of the C(3P) + NO reaction, were subsequently detected by laser induced fluorescence in the vacuum ultraviolet wavelength region. The measured rate constants are significantly larger than the estimated values in current photochemical models and do not display large variations as a function of temperature. The new rate constants are included in a 1D coupled ion-neutral model of Titans atmosphere to test their influence on the simulated species abundances. In addition, the overall description of both reactions is improved by considering the results of recent experimental and theoretical work examining the product channels of these processes. These simulations indicate that while the N(2D) + CH3CCH reaction has only a limited overall influence on Titans atmospheric chemistry, the N(2D) + CH3CN reaction could lead to the formation of significant relative abundances of cyanomethamine, HNCHCN, in the upper atmosphere.
title A Gas-Phase Kinetic Study of the N(2D) + CH3CCH and N(2D) + CH3CN Reactions
topic Earth and Planetary Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2511.06941