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S.I. Ramírez, R. Navarro-González (Instituto de Ciencias Nucleares, UNAM), P. Coll, F. Raulin (LISA, Université Paris XII)
We present a quantitative comparison, in terms of energy yields, for the production of small organics when a simulated Titan's atmosphere is subjected to a variety of energy sources. The use of gamma radiation simulates the effect caused by cosmic rays and Saturnian electrons on the stratosphere. As there has been no detection of lightning activity on Titan at the present time, the laser induced plasmas (LIP) and the arc discharges can be used to simulate the entrance of high velocity meteors into the atmosphere. We have added the effect of corona discharges (Navarro-González and Ramírez, 1997) which may develop on methane cloud particles present at tropospheric levels (Griffith et al., 1998). A mixture of methane in nitrogen (1:9) at an initial pressure of 670 mbar at 293 K, was irradiated at different times (from some minutes to several hours) and a special control in the identification (use of a GC-MS-FTIR coupled system) and quatification (use of calibration curves and calculations of dissipated power) steps, was followed to get precise and accurate energy yields. Corona processes (cold plasmas) seem to produce preferably saturated and ramified hydrocarbons, while the arc discharges (hot plasmas) produce many saturated hydrocarbons and aromatic compounds. The LIP mainly produces alkynes and benzene derivates. Gamma rays are intermediates between the hot and cold plasmas producing saturated hydrocarbons and also unsaturated and aromatic compounds. These facts evidence the difference in the mechanism of production of every compound in every energy source, and help to establish the possibility of these compounds to act as a tracer during the Huygens descend through Titan's atmosphere.
Griffith, C. A., T. Owen, G. A. Miller and T. Geballe: 1998, Nature 395, 575-578. Navarro-González, R. and S.I. Ramírez: 1997, Adv. space Res. 19(7), 1121-1132.
The author(s) of this abstract have provided an email address for comments about the abstract: sramirez@xochitl.nuclecu.unam.mx