Atmospheric pressure glow discharge generated in nitrogen-methane gas mixture: PTR-MS analyzes of the exhaust gas

This paper reports the results of an extensive study of with the in situ mass spectrometry analysis of gaseous phase species produced by an atmospheric plasma glow discharge in N<inf>2</inf>-CH<inf>4</inf> gas mixtures (with methane concentrations ranging from 1% to 4%). The products are studied using proton-transfer-reaction mass spectrometry (PTR-MS). HCN and CH<inf>3</inf>CN are identified as the main gaseous products. Hydrazine, methanimine, methyldiazene, ethylamine, cyclohexadiene, pyrazineacetylene, ethylene, propyne and propene are identified as minor compounds. All the detected compounds and their relative abundances are determined with respect to the experimental conditions (gas composition and applied power). The same molecules were observed by the Cassini-Huygens probe in Titan's atmosphere (which has same N<inf>2</inf>-CH<inf>4</inf> gas mixtures). Such, experiments show that the formation of such complex organics in atmospheres containing C, N and H, like that of Titan, could be a source of prebiotic molecules.