Interaction aerosols - plasma in Titan's ionosphere: effect on the gas phase composition

Abstract : Titan's aerosols start forming in the ionosphere, in a reactive environment hosting electrons, ions and radicals. In this work we study the interaction of the aerosols with the 'carbon free' plasma species. In this objective, analogues of Titan's aerosols (tholins) are exposed to a N2-H2 plasma in the laboratory. A previous work observed modifications on the solid aerosols [1]. Complementarily, this study investigates a possible feedback of the tholins erosion on the gas phase composition. The decrease of ammonia and the formation of carbon-bearing (and especially nitrile-bearing) species is observed by neutral and ion mass spectrometry. We suggest surface processes combining reactions with radicals and ion sputtering to explain these observations.