Abstract

For a time-resolved stimulated Raman experiment one needs two mode-locked cw dye lasers (4-ps pulses in our case). When the frequency difference between both lasers is tuned to a Raman mode the combination of these two pulses acts as a single driving force. In a pump-probe experiment the time response of the excitation is directly monitored. Three terms contribute to the signal: the instantaneous electronic response; the isotropic and anisotropic nuclear response. Using different directions of polarization for our laser beams and using a frequency difference that did not correspond to the exact Raman frequency (to study the electronic response separately) we were abte to separate these three contributions. Analysis shows there is a large difference between a two-beam (nontime-resolved) stimulated Raman measurement being almost equivalent to an ordinary Raman experiment and a four-beam time- resolved stimulated Raman measurement.

© 1986 Optical Society of America