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The role of submicrometer aerosols and macromolecules in H2 formation in the titan haze |
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| Authors: | ELO Bakes Sébastien Lebonnois Christopher P McKay |
| Institution: | a SETI Institute, Mail Stop 245-33, NASA Ames Research Center, Moffett Field, CA 94035, USA b Mail Stop 245-33, NASA Ames Research Center, Moffett Field, CA 94035, USA c Space Technology Division, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035, USA d Space Sciences Division, Mail Stop 245-3, NASA Ames Research Center, Moffett Field, CA 94035, USA |
| Abstract: | Previous studies of the photochemistry of small molecules in Titan’s atmosphere found it difficult to have hydrogen atoms removed at a rate sufficient to explain the observed abundance of unsaturated hydrocarbons. One qualitative explanation of the discrepancy nominated catalytic aerosol surface chemistry as an efficient sink of hydrogen atoms, although no quantitative study of this mechanism was attempted. In this paper, we quantify how haze aerosols and macromolecules may efficiently catalyze the formation of hydrogen atoms into H2. We describe the prompt reaction model for the formation of H2 on aerosol surfaces and compare this with the catalytic formation of H2 using negatively charged hydrogenated aromatic macromolecules. We conclude that the PRM is an efficient mechanism for the removal of hydrogen atoms from the atmosphere to form H2 with a peak formation rate of ∼ 70 cm−3 s−1 at 420 km. We also conclude that catalytic H2 formation via hydrogenated anionic macromolecules is viable but much less productive (a maximum of ∼ 0.1 cm−3 s−1 at 210 km) than microphysical aerosols. |
| Keywords: | Titan Stratospheric chemistry Hydrogen Aerosol charging |
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