PHOTOINDUCED VARIATIONS OF THE INTERNAL ELECTRIC-FIELD IN LANGMUIR-BLODGETT-FILMS WITH AZO DYE MONOLAYER

Variations of the internal electric field in a polar Langmuir-Blodgett film were investigated using modulated Stark spectroscopy. The electric field variations were caused by reorientation of molecules after illumination in the spectral absorption band characteristic of the dye (photoinduced optical anisotropy effect (POA)). It was shown that the initial spontaneous polarization in the dye monolayer can be retained when the optical anisotropy is induced by polarized light. The use of non-polarized illumination leads to a distortion of macroscopic polarity. The results obtained are discussed in terms of a light-induced recrystallization model of POA evaluated using a computer simulation.