On the Mechanism and Branching Ratio of the CN + O2 -> CO + NO Reaction Channel Using Transient IR Emission Spectroscopy

Article abstract of DOI:10.1021/j100147a006

The contribution of the title reaction to the total reaction of CN + O2 has been determined, using time-resolved IR emission spectroscopy of the product CO(ν'').This product channel is found to contribute up to 29percent with 2percent experimental variance to the total reaction.A contribution of this magnitude to the total reaction of CN + O2 by this product channel proceeding via a four-center transition state is energetically improbable.Ab initio calculations have been performed on two-and four-center transition states which are presumably formed in the reaction between CN radicals and molecular oxygen.The results of these calculations confirm the existence of a very high barrier to the formation of a four-center transition state.Consequently, a new mechanism for the formation of CO in reaction 1 is proposed.This new mechanism consists of two sequential steps rather than two parallel steps to explain the formation of the products NCO, O, and CO in the reaction CN + O2.