12C/13C Ratio in Ethane on Titan and Implications for Methane’s Replenishment

Autor:	Conor A. Nixon, R. J. Boyle, Brigette E. Hesman, George H. McCabe, Allen Lunsford, Donald E. Jennings, Pedro V. Sada, Gordon L. Bjoraker, Paul N. Romani
Rok vydání:	2009
Předmět:	Atmospheric methane Carbon-13 Carbon-12 Analytical chemistry Methane Astrobiology chemistry.chemical_compound symbols.namesake chemistry Kinetic isotope effect symbols Physical and Theoretical Chemistry Atmosphere of Titan Spectral resolution Titan (rocket family)
Zdroj:	The Journal of Physical Chemistry A. 113:11101-11106
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp903637d
Popis:	The (12)C/(13)C abundance ratio in ethane in the atmosphere of Titan has been measured at 822 cm(-1) from high spectral resolution ground-based observations. The value, 89(8), coincides with the telluric standard and also agrees with the ratio seen in the outer planets. It is almost identical to the result for ethane on Titan found by the composite infrared spectrometer (CIRS) on Cassini. The (12)C/(13)C ratio for ethane is higher than the ratio measured in atmospheric methane by Cassini/Huygens GCMS, 82.3(1), representing an enrichment of (12)C in the ethane that might be explained by a kinetic isotope effect of approximately 1.1 in the formation of methyl radicals. If methane is being continuously resupplied to balance photochemical destruction, then we expect the isotopic composition in the ethane product to equilibrate at close to the same (12)C/(13)C ratio as that in the supply. The telluric value of the ratio in ethane then implies that the methane reservoir is primordial.
Databáze:	OpenAIRE
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