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E.H. Wilson, S.K. Atreya (University of Michigan at Ann Arbor)
A prominent feature of Titan's atmosphere is a thick haze region that acts as the end product of hydrocarbon and nitrile chemistry. Using a one-dimensional photochemical model, an investigation into the chemical mechanisms responsible for the formation of this haze region is conducted. Pathways from polyynes, aromatics, and nitriles are considered. We propose that the main haze layer and the detached haze layer are produced by different chemical mechanisms, in agreement with Chassefiere and Cabane [1]. In particular, the main haze layer results from the growth of polycyclic aromatic hydrocarbons, with peak production at an altitude of 160 km (~ 3 mb). Furthermore, a less prominent detached haze layer is produced by the polymerization of polyynes and nitriles with peak production in the region of 650-900 km (7x10-5-10-6 mb). Enhancement of nitriles in the high latitudes results in a larger upper peak in haze production, dominated by nitrile chemistry.
[1] E. Chassefiere and M. Cabane, Planet. Space Sci., 43, 91-103, 1995.