Titan Atmospheric Chemistry Revealed by N₂-CH₄ Plasma Discharge Experiments

The thick atmosphere of Titan is primarily made up of nitrogen and methane. Chemistry in Titan’s N₂-CH₄ atmosphere produces complex organic aerosols. The formation processes and the chemical compositions of these aerosols are still not well understood, despite of extensive observational, laboratory, and theoretical efforts. Here, we perform a series of Titan atmosphere simulation experiments with N₂-CH₄ gas mixtures at a Titan relevant temperature (100 K). We study how initial CH₄ ratio, pressure, and flow rate affect the production rates and composition of the gas and solid products. Our results show that the production rate of the gas and solid products increases with increasing CH₄ ratio. We observe significant nitrogen incorporation into the gas and solid products. The greater degree of nitrogen incorporation in the low temperature simulation experiments suggests temperature may play an important role in nitrogen incorporation in Titan’s cold atmosphere. We find that changing the pressure or flow rate in the experiments alter the exposure time of the gas to the energy source and therefore affect the gas and solid production, emphasizing the impact of the energy flux in Titan atmospheric chemistry.