Computer Science
Scientific paper
Oct 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011epsc.conf..367v&link_type=abstract
EPSC-DPS Joint Meeting 2011, held 2-7 October 2011 in Nantes, France. http://meetings.copernicus.org/epsc-dps2011, p.367
Computer Science
Scientific paper
In the 1980's, Voyager revealed that complex organic molecules were present in Titan's atmosphere but the actual mechanisms leading to this rich chemistry were largely unknown. The recent Cassini results indicate that the chemistry ocurring in Titan's upper atmosphere is far more complex than anticipated. The detection of heavy positive and negative ions [13] reveals that much of the molecular growth occurs in the upper atmosphere rather than at lower altitudes [5, 12]. Photochemical models predict that three-body association reactions (A + B + M!AB + M) are the main production route for several hydrocarbons, including alkanes [2, 3]. The kinetic parameters of these reactions strongly depend on density and are therefore extremely difficult to constrain by experimental measurements as the low pressure of Titan's upper atmosphere cannot be reproduced in the laboratory. As a consequence, they have to be extrapolated outside the range of measurements, leading to high uncertainties. According to these extrapolations, three-body association reactions are only efficient in Titan's lower atmosphere. However, radiative association reactions (A + B ! AB + h) do not depend on pressure and can therefore still be efficient in the upper atmosphere. Unfortunately, they are largely uncharacterized and have consequently been neglected in photochemical models so far. Because of their potential importance at higher altitude, association reactions can have an important contribution to our understanding of molecular growth and better constraints for them are required. In the recent years, theoretical calculations of kinetics parameters have become more and more reliable [7]. We therefore performed ab initio transition state theory based master equation calculations for several radical-radical and radical-molecule association reactions. The computed kinetics parameters were included in our photochemical model of Titan. We present here the main results and discuss their impact for the organic cycle.
Klippenstein Stephen J.
Lavvas Panayiotis
Vuitton Veronique
Yelle Roger V.
No associations
LandOfFree
Formation of hydrocarbons on Titan: Impact of rapid association reactions at low pressure does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Formation of hydrocarbons on Titan: Impact of rapid association reactions at low pressure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Formation of hydrocarbons on Titan: Impact of rapid association reactions at low pressure will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1477132