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H. Cottin, M.C. Gazeau, J.F. Doussin, F. Raulin (Lisa, Universite Paris XII, France)
We present our latest results concerning the degradation of large organic molecules which are suspected to be present in the refractory component of cometary nucleus and dust grains. Through different processes, as thermal and photo-degradation, these molecules in solid phase can release volatile compounds, and thus act as parent molecules for extended sources. The aim of our work is to bring a better understanding of the chemical mechanisms involved during those transformations, and provide physico-chemical data such as the quantum yield of production of gaseous molecules from the solid phase as a function of the wavelength of UV irradiation.
Such data were missing to interpret and model observations of comets. Now, they allow us to answer in what extend the presence of a molecule like Polyoxymethylene in comets is relevant as an explanation for the formaldehyde extended source.
We will also show that CO (another molecule which present an extended source in comets), CO2, HCOOH, CH3OH, HCOOCH3 are produced during the irradiation of polyoxymethylene in far UV (122 and 147 nm). These molecules have already been detected in comets. Other compounds like CH3OCH2OCH3 and C3H6O3, are also photodegradation products of the Polyoxymethylene, and thus could be good candidates for future detection.
This program is supported by grants from CNES and PNP.
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The author(s) of this abstract have provided an email address for comments about the abstract: cottin@lisa.univ-paris12.fr