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 anthraquinone 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 δ 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.