ULTRAFAST RELAXATION IN THE FLUORESCENT STATE OF THE LASER-DYE DCM

Ultrafast relaxation in the fluorescent state of 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) has been interrogated by time-resolved femtosecond absorption spectroscopy both in methanol and in ethylene glycol. Following a subpicosecond rise, each frequency-specific trace in ethylene glycol exhibits either a slower increase or a slower decrease in transmission; an additional long-term decay is seen in methanol solution. The data are generally consistent with recent solvation dynamics studies that employed different probe molecules, but the solvation time we measure for ethylene glycol is an order of magnitude shorter than previously reported.