The dynamics of the CH+N2(X1Σg +)→HCN+N(4S) reaction is studied theoretically for the first time. A simple two-dimensional model is developed, treating the reaction dynamics on the doublet and on the quartet Born-Oppenheimer surfaces of CHN2 by exact quantum mechanics and the coupling between the two electronic states within first-order perturbation theory. Summation over total angular momentum states is carried out within the J-shifting approximation and the Boltzmann rate constant is computed over the temperature range of interest for combustion T≲1700 K. The reaction probability exhibits a rich resonance pattern, manifesting the existence of long-lived quasibound intermediate states on both the doublet and the quartet surfaces. These resonances affect the dynamics profoundly, being the driving force behind the spin-changing reaction. The thermal rate constant increases with temperature in an Arrhenius type fashion and in qualitative agreement with high-temperature experiments.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry