Theoretical study of the mechanism for spin-forbidden quenching process O(D-1)+CO2((1)Sigma(+)(g))-> O(P-3)+CO2((1)Sigma(+)(g))

摘要

The mechanism of the spin-forbidden quenching process O(D-1) + CO2((1)Sigma(g)(+)) -> O(P-3)+CO2((1)Sigma(g)(+)) was investigated by ab initio quantum chemistry methods. The calculations showed the singlet potential surface [O(D-1)+CO2] is attractive where a strongly bound intermediate complex CO3 is formed in the potential basin without a transition state, whereas the complex CO3 that is formed on the triplet surface [O(P-3)+CO3] must overcome a barrier. The complex channel was documented by searching minimum energy intersection points in the region of the bound complex CO3 and calculating spin-orbit coupling at the point. A direct channel was proposed by a study of cross point of singlet and triplet PESs with different collision angles and calculations of spin-orbit coupling at those cross points in a nonbound region of the [O(D-1)+CO3] system. The mechanism of the energy transfer is discussed on the basis of the theoretical results. (c) 2005 Wiley Periodicals, Inc.