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H. Cottin, M.C. Gazeau, J.F. Doussin, F. Raulin (LISA, Université Paris XII, 94000 Créteil, France)
We present a current experimental program concerning the study of the photochemical evolution of the organic matter ejected from the cometary nucleus surface : S.E.M.A.Ph.Or.E. Cométaire (a french acronym : Simulation Experimentale et Modelisation Appliquées aux PHénomènes ORganiques dans les Environnements Cométaires). The aim of the work is to understand better, using laboratory simulations, the mechanisms which are involved during the degradation of the high molecular weight organics in cometary ices and dust when they are submitted to the warming up and to the bombardment of photons in the surrounding area of the sun. This experimental study will establish correlations between the nucleus and the coma's molecular composition. Furthermore, experimental data will provide useful information to bring to a close the question of the origin of the extended sources of H2CO and CO. Polyoxymethylene, suspected to be present in the cometary nucleus, is often mentioned as a possible parent molecule for the formaldehyde's extended source, but the key physico-chemical data are missing to conclude. To test this hypothesis, irradiation of POM has been performed at 147 nm (Xenon Lamp) and 122 nm (Hydrogen Lamp) in order to obtain the quantum yield of production, from the Polyoxymethylene, of the photodegradation products. Our results showed effectively H2CO as photodegradation product as well as CO, CO2 and HCOOH. Tentative detections of CH3OCH3, CH3OCH2OCH3, CH3OCHO and C3H6O3 are also presented.
The author(s) of this abstract have provided an email address for comments about the abstract: Cottin@lisa.univ-paris12.fr