Abstract: By electrooptic measurements, with the attenuated total reflection method, we study the angular mobility of azo-dye molecules subjected to a poling electric field and/or to a photoisomerizing optical pumping. We demonstrate the site- to-site variation and the time variation of this mobility. We compare different azo-dye-containing polymer and particularly a new functionalized polyimide. A new experiment permits a spectral and temporal measurement of photoinduced dichroism and is a valuable easy complementary method for characterizing angular mobility. With this experiment, spectral shifts, photodegradation and inhomogeneity of the spectrum of dyes have been demonstrated. New result are obtained on the anistropy in spiropyran merocyanine photoisomerization. By comparing the anisotropy behavior of merocyanine with a theoretical model, we demonstrate the important role of the reverse photoisomerization in photoinduced ordering processes. !13
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