Vertical excitation energies of ClOOCl, ClClO2 and ClOClO, and photodissociation of ClOOCl. Multireference configuration interaction studies

► MRCI calculations found a state of ClOOCl with high oscillator strength close to the wavelength of the observed state at 244 nm. ► Similarly, the experimentally known states of the ClClO2 isomer have been identified. Reliable predictions of the excited states of the ClOClO isomer have been made. ► Potential curves for photodissociation of ClOOCl show the preference for dissociation into Cl + ClOO rather than into ClO + ClO. ► Qualitative arguments are made to explain the calculated oscillator strengths bases on the bonding character of the molecular orbitals.