Orientational relaxation of photomerocyanine molecules in polymeric films

We show that the photoassisted poling (PAP) produced by the photoisomerization of spiropyrans into photomerocyanines is more efficient than thermally assisted poling (TAP) at room temperature. Electrooptic measurements by attenuated total reflection (ATR) show that the angular mobility of molecules decreases with time after the optical pumping switch-off: the longer the field is maintained after pump switch-off, the better the stability of poling.