Gaussian distributions of the decay times of the singlet excited-state of aromatic-amines dispersed in polymer-films

Verbeek, G; Vaes, A; Van der Auweraer, Mark; Deschryver, Fc; Geelen, C; Terrell, D; Demeutter, S

doi:10.1021/ma00055a011

Gaussian distributions of the decay times of the singlet excited-state of aromatic-amines dispersed in polymer-films

Author:

Verbeek, G

Vaes, A ; Van der Auweraer, Mark ; Deschryver, Fc ; Geelen, C ; Terrell, D ; Demeutter, S

Keywords:

fluorescence lifetime distributions, maximum-entropy method, charge-transfer, solvation dynamics, energy migration, hole transport, free-volume, relaxation, recovery, solvent, Science & Technology, Physical Sciences, Polymer Science, FLUORESCENCE LIFETIME DISTRIBUTIONS, MAXIMUM-ENTROPY METHOD, CHARGE-TRANSFER, SOLVATION DYNAMICS, ENERGY MIGRATION, HOLE TRANSPORT, FREE-VOLUME, RELAXATION, RECOVERY, SOLVENT, 03 Chemical Sciences, 09 Engineering, Polymers, 34 Chemical sciences, 40 Engineering

Abstract:

The fluorescence maximum of amino-substituted 1,3,5-triphenylbenzenes dispersed in polystyrene and polycarbonate is shifted to longer wavelengths compared to isooctane, and this shift is larger in polycarbonate than in polystyrene. The shift is attributed to a partial relaxation of the matrix around the dispersed molecules during the excited-state lifetime. The nonexponential fluorescence decays obtained at different emission wavelengths can be analyzed globally assuming a Gaussian distribution of decay rates with a standard deviation that does not depend upon the emission wavelength. This Gaussian distribution of decay rates is attributed to a distribution of sites with different interaction with the polymer matrix. The sites giving the largest excited-state stabilization are characterized by the slowest average decay rate.