Titan , atmosphere

Voyager with an IR interferometric spectrometer (IRIS) on it [96, 97] examined Titan s atmospheric chemistry. Six simple HCs (C2H2, CjHg, C3H4, 

The results may also have imphcations for chemical evolution in the solar system. Our results suggest that nitriles, amines, hydrazines of higher molecular weight and their derivatives, such as cyano-acetylenes and dinitriles, might have been synthesized. The presence of these important compounds, as precursors of biologically important compounds on Titan, implies that the chemical reactions postulated as the formation processes of bases and amino acids on the primitive Earth may be com-moi5)lace in the planetary system. 

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Several laboratories, including that of F. Raulin in Paris (Coll et al., 1998) and of J. Ferris in the USA (Clarke and Ferris, 1997) have carried out experiments on simulated Titan atmospheres these indicate that methane and nitrogen can exist side by side (Table 3.1). 

The next most likely possibility is cometary delivery of the atmosphere but again there are some problems with the isotope ratios, this time with D/H. The cometary D/H ratios measured in methane from Halley are 31 3 x 10-5 and 29 10 x 10-5 in Hayuatake and 33 8 x 10-5 in Hale-Bopp, whereas methane measurements from Earth of the Titan atmosphere suggest a methane D/H ratio of 10 5 x 10-5, which is considerably smaller than the ratio in the comets. The methane at least in Titan s atmosphere is not exclusively from cometary sources. Degassing of the rocks from which Titan was formed could be a useful source of methane, especially as the subnebula temperature around Saturn (100 K) is somewhat cooler than that around Jupiter. This would allow volatiles to be more easily trapped on Titan and contribute to the formation of a denser atmosphere. This mechanism would, however, apply to all of Saturn s moons equally and this is not the case. 

Vacher R., Le Due E., and Fitaire M. (2000). Clustering reactions of HCNH+, HCNH+ (N2) and HCNH+ (CH4) with ethane application to Titan atmosphere. Planetary and Space Science 48 237-247... 

Acetylene is the simplest unsaturated hydrocarbons and as such an understanding of its photochemistry is important. The reactions of ethynyl radicals (C H) are important in combustion as well as in the photochemistry of Jupiter and Titan atmospheres, although, unfortunately, C2H radical has apparently only very weak and complex absorption spectra in the visible and ultraviolet region and no LIF has been found. 

Benilan, Y. Bruston, P. Raulin, F. Courtin, R. Guillemin, J. C. Absolute absorption coefficient of C6H2 in the mid-UV range at low temperature implications for the interpretation of Titan atmospheric spectra. Planet. Space Sci. 1995, 43, 83-89. 

A torus of hydrogen atoms has been detected near Saturn. The source of the hydrogen atoms is probably Titan, as argued most recently by Richardson and Eviatar (1987). Titan may also be the source of a torus of nitrogen atoms (Barbosa 1987). Thus the chemistry of the Titan atmosphere profoundly influences the distribution of material throughout the entire Saturnian system. 

Pantazis, Y., Katsoulakis, M.A., Vlachos, D.G. Parametric sensitivity analysis for biochcanical reaction networks based on pathwise information theory. BMC Bioinform. 14, 311 (2013) Peng, Z., Dobrijevic, M., Hebrard, E., Carrasco, N., Pemot, P. Photochemical modeling of Titan atmosphere at the 10 percent uncertainty horizon . Faraday Discuss. 147, 137-153 (2010) Perger, T., Kovacs, T., Turmyi, T., Trevino, C. Determination of adsorptimi and desorption parameters from ignition temperature measurements in catalytic combustion systems. J. Phys. Chem. B 107, 2262-2274 (2003)... 

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