Predissociative T1 and S1 states of carbonyl chlorofluoride (ClFCO) and their photodissociation pathways

Abstract

The low-lying electronic states of carbonyl chlorofluoride (ClFCO) were studied using the coupled-cluster singles and doubles (CCSD) method. Highly reliable values for not only the geometrical parameters, but also the vibrational properties were generated for T1 and S1 as well as S0. Potential energy surfaces (PESs) of the dissociation of the three bonds were also obtained for each electronic state separately. We found that the T1 and S1 states are both vibrationally predissociative along the C–Cl bond dissociation channel, with barrier heights of only 0.13 and 0.23 eV, respectively. The relative energies for the S1 state of the barriers to C–Cl and C–F bond dissociation are 4.93 and 6.13 eV, respectively, with respect to S0. These results suggest that a simple C–Cl bond dissociation pathway can explain the results of a previous photodissociation experiment with 235 nm (5.276 eV) light, in which only ‘Cl + FCO’ fragments were observed.