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 hydrophobic substrates. Second-harmonic generation showed that more homogeneous films were formed on hydrophilic substrates. Quantum-chemical calculations of molecular hyperpolarisabilities, taking intoaccount the absorption at the second-harmonic frequency, made it possible to determine (on the basis of a proposed model) the orientation of molecules and quadratic susceptibilities of films, which were in satisfactory agreement with the experimental results.