Chemical composition of Titan’s haze: Are PAHs present?

[1] Previous laboratory studies of haze aerosols analogous to those in Titan’s atmosphere have shown evidence of the formation of polycyclic aromatic hydrocarbons (PAHs). If present, PAHs may provide a mechanism for both particle formation and nitrogen incorporation. We have conducted new experiments simulating Titan haze production using an Aerosol Mass Spectrometer (AMS). The AMS allows us to examine the chemical structure of the haze particles under a variety of starting conditions in real-time and without collection. Our results for particles produced from a mixture of 10% CH4 in N2 are consistent with a large fraction of aromatics, including specific m/z peaks likely due to PAHs. However, at lower concentrations of CH4 (1% and lower), the mass fraction of PAHs greatly diminishes, and an aliphatic pathway dominates. Haze containing sediments may trace the history of methane on Titan through their composition. The implications for Titan haze and for observations from the Huygens probe are discussed.