Kinetic study of a N 2–CH 4 afterglow plasma for production of N-containing hydrocarbon species of Titan’s atmosphere

Abstract

We present the results from a self-consistent kinetic model simulating the afterglow of a flowing microwave discharge in pure N 2 in which CH 4 is introduced in the post-discharge. The simulation is carried out for a discharge operating at 433 MHz, in a tube of 1.9 cm inner radius, at the pressure range 26.6–133 Pa. In the post-discharge the CH 4 is primarily dissociated into CH 3 and CH 2 due to collisions with the metastables N 2 ( A 3 Σ u + ) and N 2 ( a ′ 1 Σ u - ) coming from the discharge, while HCN is obtained from collisions of CH 3 and CH 2 with N( 4S) atoms. Our calculations show that numerous species existing in Titan’s atmosphere are then formed as a result of a complex interplay kinetics. The time-evolution of the species is investigated along the afterglow as well as the possibility of these species being precursors to the formation of organic aerosols.