SINGLET AND TRIPLET STATES OF THE CO3 AND CO4 MOLECULES

Abstract The C 2v isomers of CO 2 and CO 3 and the metastable D 2d isomer of CO 4 are shown to have a similar electronic nature in both their ground singlet and excited triplet states. A simple MO model explaining the electronic structure of the species containing the cyclic CO 2 fragment was suggested. On the basis of qualitative analysis and the results of MP2/6-31G* calculations, it is shown that the radiationless singlet–triplet decay of the lowest vibrational levels of the metastable CO 4 (1 1 A 1 , D 2d ) state is hardly probable, but that such a decay seems to be possible in the case of higher-lying vibrational levels of this state.