Excited-state relaxation processes in polymethine dye molecules in polymeric media

The fluorescence decay kinetics of polymethine dye molecules in liquid (ethanol) and solid (polyurethane acrylate) media has been measured. Absorption-relaxation-emission processes are studied at wide range of excitation wavelengths (from blue to red edge of absorption band), emission wavelengths (including anti-Stokes fluorescence) and of temperature (both in elastic and glassy states of polymeric medium). Time-resolved fluorescence spectra of dye molecules in polymer confirm that, in spite of macrorigidity of polymeric medium, the characteristic time of relaxation processes within the excited state is comparable to the fluorescence lifetime.