Local-field effects in Langmuir-Blodgett films of hemicyanine and behenic acid mixtures

Abstract

The effective local-field factors for a system of adsorbed molecules are measured in Langmuir-Blodgett films consisting of mixtures of the n-docosyl homologue of hemicyanine dye and behenic acid. The effect of the local-field correction factors on the interpretation of the molecular orientation of the hemicyanine chromophore, as determined by macroscopic measurements of the optical second-harmonic generation from these molecules, is reported, and the measured values of the local-field correction factors are compared with the theory of Ye and Shen. The range of the induced-dipole–induced-dipole interaction of hemicyanine chromophores in Langmuir-Blodgett films is seen to be ∼10 Å.