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Y. Benilan, T. Ferradaz, N. Fray, A. Jolly, F. Raulin (LISA), J. C. Guillemin (ENSCR), LISA Collaboration, ENSCR Collaboration
Titan's atmosphere where the major compound is nitrogen presents a noticeable amount of methane. At high altitudes, the photo-dissociation of CH4 coupled to the dissociation of nitrogen leads to the production of numerous saturated and unsaturated hydrocarbons. Polyynes (with formula C2nH2, n>1) and cyanopolyynes (with formula HC2n+1N, n>1) are of special interest since they are predicted by photochemical models to be one of the main link between the gas phase and the solid phase visible as high altitude haze. Since several years we have conducted in our laboratory systematic spectroscopic studies of organic compounds in the infrared and ultraviolet wavelength range. Those studies include the determination of band positions and absolute intensities for organic compounds likely to be present in Titan's atmosphere. The data obtained in physical conditions representative of the studied environment are essential to allow the detection and abundance determination from observations. Those data can also help for the development of photochemical models. For the first time, cyanodiacetylene (HC5N) has been synthesised using classical organic chemistry. We will present our latest experimental results obtained on the determination of HC5N absolute absorption coefficients. In the UV range, synchrotron radiation has been used in order to determine the absolute cross section from 80 to 200 nm, at several and especially low temperatures. In the infrared, the absolute band intensities have been measured for the fundamental most intense vibrational modes. The results will be compared with theoretical predictions. Finally, the implication of those spectroscopic results for the interpretation of Cassini observations obtained by ultraviolet (UVIS) and infrared (CIRS) spectrometers will be discussed.
The author(s) of this abstract have provided an email address for comments about the abstract: benilan@lisa.univ-paris12.fr
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.