Electronic-state-resolved master equation study of energy transfer and electron-impact chemical kinetics in the nitrogen system

Abstract

This work presents a detailed investigation of electronic energy transfer mechanisms and electron-impact-induced chemical kinetics in nitrogen systems using an electronic-state-resolved master equation analysis. The master equation results demonstrate that although the state-specific distributions are highly non-Boltzmann, the ensemble-averaged electronic energy relaxation consistently follows first-order behavior, supporting the applicability of a Landau–Teller-type formulation at the macroscopic level. Comparison of relaxation times across collision partners and energy modes reveals pronounced collider-dependent behavior and confirms that electron-impact excitation proceeds several orders of magnitude faster than heavy-particle impact. The results further indicate that collisional energy exchange is governed not only by the electronic level structure but also by the intrinsic rate characteristics of the dominant collision mechanism. Analysis of electron-impact chemistry further indicates distinct ordering between energy-relaxation and chemical timescales: dissociation of N2+ occurs after near-thermalization of the electronic mode, whereas reactions of N and N2 predominantly take place under strong electronic nonequilibrium. State-resolved population dynamics highlight preferential ionization and dissociation pathways from selected excited states, which significantly influence the partitioning of electronic energy during chemical reactions. The derived global rate coefficients and energy-loss ratios provide physically grounded macroscopic parameters for reduced-order modeling, enabling consistent closure of chemistry–electronic coupling in multi-temperature formulations without reliance on empirical scaling factors.