Nonlinear optical and structural properties of noncentrosymmetric organic thin films obtained by oblique incidence molecular beam deposition

摘要

Acentric films of 4-[trans-(pyridin-4-ylvinyl)] benzoic acid (PVBA) are grown on amorphous substrates by oblique incidence organic molecular beam deposition. The molecules in the bulk of the films show a preferential noncentrosymmetric in-plane orientation determined by the molecular beam direction. We investigate this symmetry-breaking mechanism by studying the structural and nonlinear optical properties of the films as a function of deposition conditions, with special focus on the molecular beam angle of incidence. The most pronounced preferential orientation of the molecules is found for an incident angle of 50 +/- 10 deg relative to the substrate normal. (C) 2004 Optical Society of America.