The nitrogen chemistry of titan's upper atmosphere revealed

V. Vuitton, Roger Yelle, V. G. Anicich

Research output: Contribution to journalArticle

156 Citations (Scopus)

Abstract

Titan's atmosphere is unique because dissociation of N2 and CH4, the primary atmospheric constituents, provides the H, C, and N atoms necessary for the synthesis of complex organic molecules. The first steps in the synthesis of organic molecules occur in the upper atmosphere where energetic photons and electrons dissociate N2 and CH4. We determine the abundance of a suite of nitrogen-bearing molecules in Titan's upper atmosphere through analysis of measurements of the ionospheric composition made by the Ion Neutral Mass Spectrometer (INMS) on the Cassini spacecraft. We show that the density of ions in Titan's upper atmosphere depends closely on the composition of the neutral atmosphere and that, for many species, measurement of associated ions coupled with simple chemical models provides the most sensitive determination of their abundance. With this technique we determine the densities of C2H4, C4H2, HCN, HC3N, CH3CN, NH3, C2H3CN, C2H5CN, and CH2NH. The latter four species have not previously been detected in the gas phase on Titan, and none of these species have been accurately measured in the upper atmosphere. The presence of these species implies that nitrogen chemistry on Titan is more extensive than previously realized.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume647
Issue number2 II
DOIs
StatePublished - Aug 20 2006

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Titan
upper atmosphere
chemistry
nitrogen
ionospheric composition
ion
neutral atmospheres
Titan atmosphere
molecules
ions
synthesis
atmosphere
mass spectrometers
spacecraft
dissociation
vapor phases
spectrometer
energetics
photons
electron

Keywords

  • Astrochemistry
  • Planets and satellites: individual (Titan)

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

The nitrogen chemistry of titan's upper atmosphere revealed. / Vuitton, V.; Yelle, Roger; Anicich, V. G.

In: Astrophysical Journal, Vol. 647, No. 2 II, 20.08.2006.

Research output: Contribution to journalArticle

Vuitton, V. ; Yelle, Roger ; Anicich, V. G. / The nitrogen chemistry of titan's upper atmosphere revealed. In: Astrophysical Journal. 2006 ; Vol. 647, No. 2 II.
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