New insights into the kinetics of the reaction of vinyl radical with nitrogen dioxide

The kinetics of the reactions of vinyl radical with NO₂ have been investigated using ab initio kinetics calculations. The potential energy profile is constructed at the CCSD(T)-F12a/aVTZ-F12//M06-2X/aug-cc-pVDZ level of theory. Micro-canonical variational transition state theory and Rice-Ramsperger-Kassel-Marcus/Master Equation calculations were performed to obtain temperature- and pressure-dependent rate coefficients. The reaction of vinyl radical and NO₂ can start from an attack of the vinyl radical on the N-atom or O-atom site of NO₂, followed by a number of competing reaction pathways (rearrangement and decompositions of nitro or nitrite intermediate). The bimolecular product channel generating NO + CH₂CHO was found to be the most favorable. Additionally, for the NO release, both the barrier-less process and the pathway via a saddle point are identified in this study. The proposed reaction pathways and calculated rate coefficients were incorporated into a kinetic model. The results illustrate that the present calculation remarkably affects the model performance in terms of predicting species evolution. After incorporating the new Ċ₂H₃ + NO₂ kinetics, the predictions of species evolution are in reasonable agreement with the experimental measurements.