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 experiment is not determined by the duration of pump and probe pulses but by the cross-correlation time between pump and probe lights. This idea is experimentally examined for Raman scattering from electronically excited trans-stilbene in n-hexane solution. In accordance with the prediction, the picosecond decay of the Raman band at 1560 cm^-1 arising from the stilbene molecules in the S₁ state is observed by use of nanosecond pump and probe pulses, while no decay is observed for the Raman bands of the solvent.