title: Production of hydrocarbons and nitriles by electrical processes in Titan's atmosphere.
abstract: Although lightning has not been observed in Titan's atmosphere, the presence of methane rain in the troposphere suggests the possibility of electrical activity in the form of corona and/or lightning discharges. Here we examine the chemical effects of these electrical processes on a Titan simulated atmosphere composed of CH4 in N2 at various mixing ratios. Corona discharges were simulated in two different experimental arrays. For the detection of reactive intermediates we used a mass spectrometer to study the main positive ions arising by bombarding low-energy electrons from a hot filament into low-pressure methane. The final stable products, generated by applying a high voltage in a coaxial reactor with either positive or negative polarity, were separated and detected by gas chromatography-Fourier transform infrared spectroscopy and electron impact mass spectrometry (GC-FTIR-MS). Lightning discharges were simulated by a hot and dense plasma generated by a Nd-YAG laser and the final products were separated and detected by GC-FTIR-MS. Corona discharges produce linear and branched hydrocarbons as well as nitriles whereas lightning discharges generate mainly unsaturated hydrocarbons and nitriles. Lightning discharges are about 2 orders of magnitude more efficient in product formation than corona discharges.
authors.affiliation: Laboratorio de Quimica de Plasmas y Estudios Planetarios, Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Circuito Exterior, Ciudad Universitaria, Apartado Postal 70-543, Mexico D.F. 04510, Mexico.
authors.forename: R
authors.initials: R
authors.lastname: Navarro-Gonzalez
authors.forename: S I
authors.initials: SI
authors.lastname: Ramirez
authors.forename: J G
authors.initials: JG
authors.lastname: de la Rosa
authors.forename: P
authors.initials: P
authors.lastname: Coll
authors.forename: F
authors.initials: F
authors.lastname: Raulin
mesh_terms: D000114:Acetylene / Q000138:chemical synthesis; D001272:Atmosphere / Q000737:chemistry*; D004560:Electricity; D008401:Gas Chromatography-Mass Spectrometry; D006838:Hydrocarbons / Q000138:chemical synthesis*; D006856:Hydrogen Cyanide / Q000138:chemical synthesis; D007477:Ions / Q000032:analysis; D007834:Lasers; D008697:Methane / Q000737:chemistry; D009570:Nitriles / Q000138:chemical synthesis*; D009584:Nitrogen / Q000737:chemistry; D009930:Organic Chemicals / Q000138:chemical synthesis; D018539:Saturn; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D006838:Hydrocarbons; D007477:Ions; D009570:Nitriles; D009930:Organic Chemicals; D006856:Hydrogen Cyanide; D009584:Nitrogen; D000114:Acetylene; D008697:Methane