Internal Conversion Dynamics of Benzene Studied by Femtosecond Pump-probe Mass Spectroscopy

The detection of benzene photoions in pump-probe experiments with the femtosecond laser pulse at 400 and 266 nm has allowed to study the dynamics of the internal conversion after excitation to the electronic S2 state. For the S2 state, an extremely short lifetimeτD1=(48±1)fs has been obtained, whereas the lifetime τD2=(6.5±0.2)ps of the S1state populated by the internal conversion from the S2 state is longer than that of the S2 state. The deactivation ofthe S2 state as well as the S1state has been explained by the internal conversion to lower electronic states caused by the conical intersection of the corresponding potential surfaces.