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Abstract
Mutual-neutralization (MN) of cation-anion pairs is one of the key processes that determines the chemical compositions of reacting gas mixtures found in combustion, plasmas, and cosmic gas clouds. In the last few decades, experiments and modeling investigations have been conducted in free-molecular limit. However, the MN process is less extensively studied at near or beyond atmospheric pressure for relevant applications and the measured rate constant shows a clear pressure dependency. The present work focuses on developing a method based on trajectory simulation for a pressure range from the free molecular limit to atmospheric pressure. Langevin dynamics is incorporated to capture the effect of neutral atoms and the Landau-Zener formula will be used to calculate the state transition probability based on the instantaneous crossing velocities, the product branching ratio and the reaction cross-section are evaluated by Monte-Carlo method. Over the pressure range tested, simulation results show reasonable agreement with experimental results.
