Thermally induced spectral diffusion of Rhodamine 3B in viscous polyols

Abstract

Energy shifts of the ν 00 vibronic near the fluorescence maxima of Rhodamine 3B, in 1,5-pentanediol and glycerol, are studied in the range 275< T<341 K. The frequencies red shift sharply with the temperature increase. The spectral diffusion can be related with temperature induced changes from the relaxation pattern of the polyols on the basis of simple continuum calculations. The correlation of the spectral diffusion process with the time scale of dipole memory loss and with the α-relaxation process is presented. Average solvation times in glycerol are estimated using a mode coupling theory description of the solvation autocorrelation function.