The photodissociation of SO2 between 200 and 197Â nm

Pump-probe experiments on the C state of SO2 have been performed to assess the details of the oxygen photodissociation process between 197 and 200 nm. The findings show that a prompt dissociation event occurs in less than 265, but more than 100 fs. The reorganization of internal energy occurs in 15 or 28 ps depending upon the excitation energy; the change in lifetime represents contributions from asymmetric vibrational states seen in previous experiments. In addition, a long-lived species (lifetime >150 ps) exists that does not decay on the timeframe of our experiment. These findings are discussed in comparison to previous studies, particularly in the context of an avoided crossing in this region of the potential energy surface of SO2.