Quantum and Quasi-classical Dynamics of the C($^{3}$P) + O$_{2}$($^3\Sigma_{g}^{-}$) $\rightarrow$ CO($^{1}\Sigma^{+}$)+ O($^{1}$D) Reaction on Its Electronic Ground State

Abstract

The dynamics of the C($^{3}$P) + O$_{2}$($^3\Sigma_{g}^{-}$) $\rightarrow$ CO($^{1}\Sigma^{+}$)+ O($^{1}$D) reaction on its electronic ground state is investigated by using time-dependent wave packet propagation (TDWP) and quasi-classical trajectory (QCT) simulations. For the moderate collision energies considered ($E_{\rm c} = 0.001$ to 0.4 eV, corresponding to a range from 10 K to 4600 K) the total reaction probabilities from the two different treatments of the nuclear dynamics agree very favourably. The undulations present in $P(E)$ from the quantum mechanical treatment can be related to stabilization of the intermediate CO$_2$ complex with lifetimes of on the 0.05 ps time scale. This is also confirmed from direct analysis of the QCT trajectories. Product diatom vibrational and rotational level resolved state-to-state reaction probabilities from TDWP and QCT simulations also agree well except for the highest product vibrational states $(v' \geq 15)$ and for the lowest product rotational states $(j' \leq 10)$. Opening of the product vibrational level CO$(v' = 17)$ requires $\sim 0.2$ eV from QCT and TDWP simulations with O$_2$($j=0$) and decreases to 0.04 eV if all initial rotational states are included in the QCT analysis, compared with $E_{\rm c} > 0.04$ eV obtained from experiments. It is thus concluded that QCT simulations are suitable for investigating and realistically describe the C($^{3}$P) + O$_{2}$($^3\Sigma_{g}^{-}$) $\rightarrow$ CO($^{1}\Sigma^{+}$)+ O($^{1}$D) reaction down to low collision energies when compared with results from a quantum mechanical treatment using TDWPs.