Optical properties of Langmuir-Blodgett films investigated by a photoacoustic technique.

A photoacoustic (PA) technique based on a four-layer prism configuration has been developed for nondestructive determination of the optical properties of Langmuir-Blodgett (LB) films, in which the PA signal amplitudes are measured as functions of the incident angle of light. With this technique the experimental PA angular spectra of manganese stearate and cadmium stearate LB films were obtained. Based on the electromagnetic theory and taking into account the anisotropic properties of LB films, as well as use of the numerical optimization method, we have simultaneously determined the optical constants and thicknesses of films based on experimental PA angular spectra.