AGGREGATION OF CHLOROPHYLL & B IN POLYMER FILMS

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Fluorescence emission anisotropies, r, and mean lifetimes of 4-dimethylamino-omega-diphenylphosphinyl-trans-styrene (DDPS) were measured in n-butanol at different temperatures from 20 to 80xC for one- and two-photon excitation. When increasing the temperature, the lifetime decreased from 32 to 12 ps. The anisotropy values, however, remained constant (0.315 and 0.445 for one- and two-photon excitation, respectively) and were found to be temperature independent. For DDPS in glycerol at -5xC, where rotational diffusion does not occur during the excited state lifetime, the limiting emission anisotropies were r0 = 0.382 and r0 = 0.545 for one- and two-photon excitation, respectively, very little differing from the fundamental emission anisotropies rf = 2/5 and rf= 4/7. The small differences rf - r0 can be due to vibrations performed after excitation by the DDPS molecule as a result of the initial shock.