PHOTOCHEMICAL FLUORESCENCE PROBES - RATE DISTRIBUTIONS IN SOLID POLYMERS

Non-exponential fluorescence decays due to the photochemical reaction of 10-cyano-9-tert-butyl-anthracene towards the Dewar isomer are analy zed to gain information on the free volume of a polymer glass (poly-n- butyl-methacrylate) at different temperatures, The simple model of a m ultiexponential fitting procedure is well suited to following the temp erature dependence in the envelope of this distribution qualitatively, but it fails to detect finer structures. More demanding methods (maxi mum entropy and exponential series) result in at least trimodal distri butions indicating preferred polymer free volume voids within a broad distribution. Increasing temperature favours the decay time range asso ciated with the largest free volume void.