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Nitrogen incorporation in ch4-n2 photochemical aerosol produced by far uv irradiation
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Jimenez, Jose L. Trainer, Melissa G. Yung, Yuk L. Toon, Owen B. Tolbert, Margaret A. |
| Copyright Year | 2012 |
| Description | Nitrile incorporation into Titan aerosol accompanying hydrocarbon chemistry is thought to be driven by extreme UV wavelengths (lambda < 120 nm) or magnetospheric electrons in the outer reaches of the atmosphere. Far UV radiation (120 - 200 nm), which is transmitted down to the stratosphere of Titan, is expected to affect hydrocarbon chemistry only and not initiate the formation of nitrogenated species. We have examined the chemical properties of photochemical aerosol produced at far UV wavelengths using a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS), which allows for elemental analysis of particle-phase products. Our results show that aerosol formed from CH4/N2 photochemistry contains a surprising amount of nitrogen, up to 16% by mass, a result of photolysis in the far UV. The proportion of nitrogenated organics to hydrocarbon species is shown to be correlated with that of N2 in the irradiated gas. The aerosol mass greatly decreases when N2 is removed, indicating that N2 plays a major role in aerosol production. Because direct dissociation of N2 is highly improbable given the immeasurably low cross-section at the wavelengths studied, the chemical activation of N2 must occur via another pathway. Any chemical activation of N2 at wavelengths > 120 nm is presently unaccounted for in atmospheric photochemical models. We suggest that reaction with CH radicals produced from CH4 photolysis may provide a mechanism for incorporating N into the molecular structure of the aerosol. Further work is needed to understand the chemistry involved, as these processes may have significant implications for prebiotic chemistry on the early Earth and similar planets. |
| File Size | 694307 |
| Page Count | 36 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20120009529 |
| Archival Resource Key | ark:/13960/t54f6s96m |
| Language | English |
| Publisher Date | 2012-04-01 |
| Access Restriction | Open |
| Subject Keyword | Lunar And Planetary Science And Exploration Methane Photochemical Reactions Chemical Analysis Atmospheric Models Nitrogen Mass Spectrometers Photolysis Time of Flight Spectrometers Aerosols Nitriles Chemical Evolution Titan Atmosphere Titan Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
