Thermally induced spectral diffusion of Rhodamine 3B in viscous polyols

Energy shifts of the v(00) vibronic near the fluorescence maxima of Rhodami ne 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 th e relaxation pattern of the polyols on the basis of simple continuum calcul ations. The correlation of the spectral diffusion process with the time sca le of dipole memory loss and with the a-relaxation process is presented. Av erage solvation times in glycerol are estimated using a mode coupling theor y description of the solvation autocorrelation function. (C) 2001 Elsevier Science B.V. All rights reserved.