Computational Study on the Mechanisms and Pathways of the Atmospheric NH2 + BrO Reaction

Abstract

AbstractThe NH2 radical reaction with BrO was characterized by combining the second‐order Møller–Plesset perturbation theory (MP2) with a 6–311++G(d,p) basis set, followed by kinetic analyses using the Rice–Ramsperger–Kassel–Marcus (RRKM) theory and transition‐state (TST) theory to forecast the product distribution and thermal rate coefficients. Addition/elimination and H‐abstraction mechanisms are observed, and three products are identified: P1 (HBr + HNO), P2 (NBr + H2O) and P3 (3NH + HOBr). At atmospheric pressure, P1 (HBr + HNO), generated by the association/elimination channel, represents the primary products between 200–500 K; the direct H‐abstraction leading to P3 (3NH + HOBr) plays a significant role above 500 K. However, at the high‐pressure limit, IM1 [BrONH2] generated by collisional stabilization is dominant between 200–500 K; the direct H‐abstraction leading to P3 (3NH + HOBr) was the major channel at high‐temperature. Moreover, the total rate constants are pressure independent; however the individual rate constants are sensitive to pressure.