N<inf>2</inf> state population in Titan's atmosphere

P. Lavvas, Roger Yelle, A. N. Heays, L. Campbell, M. J. Brunger, M. Galand, V. Vuitton

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

We present a detailed model for the vibrational population of all non pre-dissociating excited electronic states of N<inf>2</inf>, as well as for the ground and ionic states, in Titan's atmosphere. Our model includes the detailed energy deposition calculations presented in the past (Lavvas, P. et al. [2011]. Icarus 213(1), 233-251) as well as the more recent developments in the high resolution N<inf>2</inf> photo-absorption cross sections that allow us to calculate photo-excitation rates for different vibrational levels of singlet nitrogen states, and provide information for their pre-dissociation yields. In addition, we consider the effect of collisions and chemical reactions in the population of the different states. Our results demonstrate that above 600km altitude, collisional processes are efficient only for a small sub-set of the excited states limited to the A and W(ν=0) triplet states, and to a smaller degree to the a' singlet state. In addition, we find that a significant population of vibrationally excited ground state N<inf>2</inf> survives in Titan's upper atmosphere. Our calculations demonstrate that this hot N<inf>2</inf> population can improve the agreement between models and observations for the emission of the c4' state that is significantly affected by resonant scattering. Moreover we discuss the potential implications of the vibrationally excited population on the ionospheric densities.

Original languageEnglish (US)
Pages (from-to)29-59
Number of pages31
JournalIcarus
Volume260
DOIs
StatePublished - Nov 1 2015

Fingerprint

Titan atmosphere
Titan
atmosphere
upper atmosphere
chemical reaction
cross section
collision
scattering
ground state
photoabsorption
photoexcitation
nitrogen
absorption cross sections
ionospherics
atomic energy levels
chemical reactions
energy
dissociation
collisions
high resolution

Keywords

  • Aeronomy
  • Atmospheres, chemistry
  • Titan, atmosphere
  • Ultraviolet observations

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Lavvas, P., Yelle, R., Heays, A. N., Campbell, L., Brunger, M. J., Galand, M., & Vuitton, V. (2015). N<inf>2</inf> state population in Titan's atmosphere. Icarus, 260, 29-59. https://doi.org/10.1016/j.icarus.2015.06.033

N<inf>2</inf> state population in Titan's atmosphere. / Lavvas, P.; Yelle, Roger; Heays, A. N.; Campbell, L.; Brunger, M. J.; Galand, M.; Vuitton, V.

In: Icarus, Vol. 260, 01.11.2015, p. 29-59.

Research output: Contribution to journalArticle

Lavvas, P, Yelle, R, Heays, AN, Campbell, L, Brunger, MJ, Galand, M & Vuitton, V 2015, 'N<inf>2</inf> state population in Titan's atmosphere', Icarus, vol. 260, pp. 29-59. https://doi.org/10.1016/j.icarus.2015.06.033
Lavvas P, Yelle R, Heays AN, Campbell L, Brunger MJ, Galand M et al. N<inf>2</inf> state population in Titan's atmosphere. Icarus. 2015 Nov 1;260:29-59. https://doi.org/10.1016/j.icarus.2015.06.033
Lavvas, P. ; Yelle, Roger ; Heays, A. N. ; Campbell, L. ; Brunger, M. J. ; Galand, M. ; Vuitton, V. / N<inf>2</inf> state population in Titan's atmosphere. In: Icarus. 2015 ; Vol. 260. pp. 29-59.
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