Ultrafast photodissociation dynamics of diphenylcyclopropenone studied by time-resolved impulsive stimulated Raman spectroscopy

We studied ultrafast photodissociation reaction of diphenylcyclopropenone (DPCP) in solution by time-resolved impulsive stimulated Raman spectroscopy (TR-ISRS) using sub-6-fs pulses. The obtained femtosecond time-resolved Raman data of excited-state DPCP did not show any noticeable spectral change during its lifetime of 180 fs. This indicates that photoexcited DPCP is trapped at the excited-state potential energy minimum before undergoing the photodissociation, which is consistent with the predissociation picture of ultrafast photodissociation reaction of DPCP. The present study demonstrates the high capability of TR-ISRS for structural characterization of short-lived reactive transients that decay within only a few hundreds of femtoseconds.