INCOHERENT TIME-RESOLVED PUMP-PROBE RAMAN-SPECTROSCOPY

A new experimental method for ultrafast time-resolved pump-probe Raman spectroscopy by use of temporally incoherent light is proposed. It is predicted that the temporal resolution of this pump-probe Raman exper iment is not determined by the duration of pump and probe pulses but b y the cross-correlation time between pump and probe lights. This idea is experimentally examined for Raman scattering from electronically ex cited trans-stilbene in n-hexane solution. In accordance with the pred iction, the picosecond decay of the Raman band at 1560 cm-1 arising fr om the stilbene molecules in the S1 state is observed by use of nanose cond pump and probe pulses, while no decay is observed for the Raman b ands of the solvent.