Direct imaging of the ultrafast internal conversion in isolated piperidine

Abstract

The ultrafast internal conversion (IC) of piperidine has been observed by femtosecond time-resolved photoelectron imaging (TRPEI) coupled with time-resolved mass spectroscopy. The time evolution of the parent ion is well described by a rapid dephasing pathway with 62fs and a slow channel with 184fs. The fast dephasing is ascribed to the IC from the S1 state to S2 state, and the slower one is attributed to the IC through the S2/S0 conical intersections. The study provides a general view of the piperidine photophysics, which are driven by the interplay between these excited surfaces and the ground state.