Theoretical investigations of the N2H2+ cation and of its reactivity

OOCO+ cation. II. Its role during the atmospheric ion-molecule reactions

For the charge transfer and vibrational and electronic deexcitations between O2/O2+ + CO+/CO, O/O+ + CO2+/CO2, and C/C+ + O3+/O3, multistep reaction pathways are discussed in light of the theoretical data of this and previous paper together with close comparison with the experimental observations. Our calculations show that these pathways involve both the long range and molecular region ranges of the potential energy surfaces of the electronic states of the stable isomers of OOCO+ and mostly those of the weakly bound charge transfer complex OOCO+. The couplings between these electronic states such as vibronic, Renner-Teller, Jahn-Teller, and spin orbit are viewed to play crucial roles here. Moreover, the initial orientation of the reactants, in the entrance channels, strongly influences the reaction mechanisms undertaken. We propose for the first time a mechanism for the widely experimentally studied spin-forbidden exothermic O+((4)S(u))+CO2(X (1)Sigmag+)-->O2+(X (2)Pi(g))+CO(X (1)Sigma+) reaction where the O turns around the OCO molecule.