Microscopic treatment of substrate effects on linear and quadratic optical response of model Langmuir-Blodgett multilayers

Abstract

Microscopic calculations of linear and quadratic nonlinear optical response in model Langmuir-Blodgett films treated by the method of images are reported. The films are on a substrate, and the effect of the substrate is significant in the first two layers and greatest for tilted molecules with their head groups adjacent to the substrate. The main effect is to lower the symmetry relative to a free-standing film. Calculations for stearic acid films demonstrate that the substrate effect is most important for molecules with nonuniform response.