Ultrafast Internal Conversion Dynamics of 2-Chloropyridine by Femtosecond Time-Resolved Photoelectron Imaging

O644; Ultrafast internal conversion dynamics of 2-chloropyridine were studied by femtosecond time-resolved photoelectron imaging spectroscopy coupled with time-resolved mass spectroscopy. The ultrafast internal conversion from the second excited state (S2) to the first excited state (S1) via an adjacent conical intersection within (162±5) fs was clearly observed from the time-dependence of the photoelectron spectra. The subsequent deactivations involved the coupling of S2/S0(the ground state) and S1/S0 conical intersections, which occurred on a timescale of about (5.5±0.3) ps, and led to the internal conversion to the ground state from the S2 and S1 states.