Elastic anisotropies in 22-tricosenoic acid Langmuir-Blodgett films: surface pressure and dipping direction

Abstract

The authors present the Brillouin spectra obtained from 22-tricosenoic acid, deposited onto a silicon substrate using the Langmuir-Blodgett technique, for hypersound propagation both parallel and perpendicular to the dipping direction. The spectra show the expected elastic anisotropy of the films and also demonstrate that the velocities increase with deposition surface pressure. Elastic constants are obtained for a film deposited at a surface pressure of 47.5+or-2.5 mN m-1 by fitting the hypersound velocity data to a model of the film.