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H. Imanaka, B.N. Khare, E.L.O. Bakes (SETI Inst./NASA Ames Research Center), C.P. McKay (NASA Ames Research Center), J.E. Elsila, D.R. Mcglothlin, R.N. Zare (Stanford University), S. Sugita, T. Matsui (Univ. of Tokyo)
We have undertaken a detailed study of the gas phase products formed from a mixture consisting of 10 90 simulates Titanfs atmosphere subjected to irradiation while intercepting the magnetosphere of Saturn. Similar gas phase studies have been conducted by Gupta et al. (1981), Thompson et al. (1991), Coll et al. (1999), and Khare et al. (2002). Khare et al. (1984) have measured the optical constants from soft X-ray to microwave frequencies of the resulting tholin produced at a total pressure of 0.2 mb only. In the present investigation we examine the gas phase products at a variety of pressures and measure the optical properties of subsequent tholins produced corresponding to that pressure. We find that the gas phase product distribution is sensitive to the pressure at which they are produced and detectable changes in the optical constants of the corresponding tholin are found. The major gas phase products are HCN, C2H2, CH3CN, NH3, C2H6, and C6H6. The theoretical models by Bakes et al. (2002) and Lebonnois et al. (2002) predicts the formation of polycyclic hydrocarbons (PAHs) in the atmosphere of Titan. Although only benzene has been detected, we have found higher mass PAHs adsorbed on tholins which are revealed on examination by microprobe two-step laser desorption/laser ionization mass spectrometry. The distribution of adsorbed PAHs in the tholins produced at specific pressure and the optical constants of the corresponding tholin along with the gas phase products will be presented.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.