USING OPTICAL COHERENCE TO MEASURE THE ULTRAFAST ELECTRONIC DEPHASING OF LARGE MOLECULES IN ROOM-TEMPERATURE LIQUIDS

The bleaching dynamics of the dye molecule HITCI in ethylene glycol are examined using variable duration femtosecond laser pulses. The transient signal observed around zero delay time is composed of both population dynamics and coherent coupling between the pump and probe laser beams. The relative contribution of coherent coupling increases as the laser pulse width is varied from 23 to 54 fs. These results indicate that the electronic dephasing of HITCI occurs on a time scale competitive with the laser pulse widths being used. We further demonstrate that quantitative molecular information can be extracted from coherent coupling contributions to the transient bleaching data. The wavelength dependence of the bleaching dynamics is also briefly discussed.