NONLINEAR-OPTICAL PROPERTIES OF LANGMUIR- BLODGETT RHODAMINE DYE FILMS

An investigation was made of nonlinear optical properties of Langmuir- Blodgett films of rhodamine B and rhodamine 6G on hydrophilic and hydr ophobic substrates. Second-harmonic generation showed that more homoge neous films were formed on hydrophilic substrates. Quantum-chemical ca lculations of molecular hyperpolarisabilities, carried out subject to absorption at the second-harmonic frequency, made it possible to deter mine (on the basis of a proposed model) the orientation of molecules a nd quadratic susceptibilities of films, which were in satisfactory agr eement with the experimental results.