STARK SPECTROSCOPY OF LANGMUIR-BLODGETT MONOLAYERS AND MULTILAYERS

The electrical (capacity and conductivity) and electro-optical (Stark spectra) properties were investigated for monolayers of an anthraquionone dye. The polar structure of the monolayers results in the appearance of the linear Stark effect with a field-induced change ΔT in the optical transmission proportional to the difference Δμ of the dipole moments for an excited and the ground molecular states. Multilayers were shown to be non-polar owing to the effects of molecular association. In the latter case only the quadratic Stark effect is observed with ΔT proportional to the difference Δα of the polarizabilities of an associated excited state and the ground state. It was also shown that the electric field distribution across an ultrathin Langmuir-Blodgett film is extremely non-uniform.