Ultrasonic Absorption and Dispersion in Cholesteryl Esters

Abstract

Abstract Propagation of ultrasonic longitudinal waves at frequencies from 10 to 70 MHz was studied in three 18-carbon unsaturated fatty acid esters of cholesterol-cholesteryl oleate (CO), cholesteryl linoleate (CL), and cholesteryl linolenate (CLn)-and three mixtures of the esters-80%CL-20%CO, 95%CL-5%CO, and 80%CLn-20%CO. The study was made in temperature ranges over which all systems exhibited the isotropic, cholesteric, and smectic states. Measurements of the ultrasonic attenuation coefficient and velocity of propagation of longitudinal waves were made by a variable pathlength pulse transmission technique. Density measurements as a function of temperature were also made.