Abstract

High resolution Brillouin spectroscopy has been used to measure the elastic constants of highly oriented thin films of cadmium arachidate. Samples of cadmium arachidate were prepared on molybdenum and glass substrates using the Langmuir-Blodgett technique. Thermally excited guided acoustic waves in the thin films were probed using Brillouin spectroscopy. The scattered light was spectrum analyzed with a high resolution tandem multipass interferometer to measure the Brillouin shifted signals. The elastic constants were estimated by fitting a model of the guided acoustic waves within a hexagonal thin film on an isotropic substrate to the Brillouin shift data. The shear elastic constant was found to be small c₄₄ < 4.0 × 10⁸ N/m². The elastic constant corresponding to the longitudinal velocity along the molecular axis was quite large, c₃₃ = 2.1 × 10¹⁰ N/m².

© 1986 Optical Society of America