Second-harmonic generation in interleaved hemicyanine/nitrogencrown Langmuir - Blodgett multilayers

Abstract

A novel disc-like amphiphilic molecule, with two-chain nitrogencrown was adopted as a spacer material for fabrication of optical nonlinear Langmuir - Blodgett (LB) multilayers. The intensity of second-harmonic generation (SHG) increased quadratically with the bilayer number (up to 116 bilayers) in Y-type hemicyanine/nitrogencrown interleaving LB multilayers due to improvement of the structural properties by insertion of the long hydrophobic tail of hemicyanine molecules between two chains of nitrogencrown molecules. The second-order susceptibility pM (or esu) was obtained by measuring SHG from the hemicyanine samples.