The OClO dissociation

was investigated by resonance enhanced multiphoton ionisation / time-of-flight (REMPI-TOF) measurements of the O(³P_J) and ClO(²Π_Ω) fragments.

The dissociation leads to highly vibrationally excited ClO and correspondingly slow O fragments. The bimodal behavior of the velocity and energy distributions leads us to conclude that the fragmentation follows two different dissociation pathways with a broad velocity distribution.

Channeling the vibrational energy of the excited OClO into the asymmetric stretch coordinate, the parent molecule decays via a barrier on the A²A₂ potential energy surface, releasing the difference between photon energy and barrier height as ClO vibration. Extremely vibrationally excited ClO is likely to be produced following conversion of the OClO from the initially excited ²A₂ surface to the ²B₂ surface, releasing the total available energy into ClO internal energy.

The fragmentation process is spin selective. The fraction of highly vibrationally excited ClO increased with increasing J of the oxygen partner fragment. As an anisotropic spatial distribution is observable the decay time is expected to be of the order of a few femtoseconds.

The extreme internal excitation of the ClO product opens up new reaction schemes in atmospheric chemistry, such as the reaction of ClO with N₂. Therefore the OClO dissociation needs to be considered as a possible chlorine atom source in the atmosphere.