PICOSECOND POLARIZATION SPECTROSCOPY OF DYE MOLECULES.

Data are presented on the propagation of picosecond pulses in weakly excited dye solutions. The authors report a new version of the pump and probe technique. measuring induced dichroism at variable probe pulse frequency. It is shown that the so-called ″coherence peak″ in experiments with equal pump and probe frequencies depends on the vibronic relaxation times in different electronic states. Interpretation of the experimental data is considerably facilitated at the low excitation intensities used here. Experimental results for vibronic and rotational time constants on phenoxazone 9 and rhodamine 6G are presented.