In this paper we describe a first quantitative search for several molecules in Titans stratosphere ni Cassini CIRS infrared spectra. These are: ammonia (NH3), methanol (CH3OH), formaldehyde (H2CO), and acetonitrile (CH3CN), all of which are predicted by photochemical models but only the last of which observed, and not in the infrared,. We find non-detections in all cases, but derive upper limits on the abundances from low-noise observations at 25 degreesS and 75 degreesN. Comparing these constraints to model predictions, we conclude that CIRS is highly unlikely to see NH3 or CH3OH emissions. However, CH3CN and H2CO are closer to CIRS detectability, and we suggest ways in which the sensitivity threshold may be lowered towards this goal.
Revised: August 11, 2011 |
Published: November 1, 2010
Citation
Nixon C.A., R.K. Achterberg, N.A. Teanby, P.G. Irwin, J.M. Flaud, I. Kleiner, and A. Dehayem-kamadjeu, et al. 2010.Upper limits for undetected trace species in the stratosphere of Titan.Faraday Discussions 147.PNNL-SA-72540.doi:10.1039/C003771K