Structural study of a new Langmuir-Blodgett material designed for nonlinear optical applications

Abstract

A new bifunctional material, [2-nitro-5-(N-methyl-N-octadecylamino)benzoic acid] (NMOB), has been synthesized and its film forming properties investigated by the Langmuir-Blodgett technique. Pressure-area isotherms indicate that NMOB forms stable monolayers below 40 mN/m which can be transferred to solid substrates. Multilayered samples were prepared on both transmission and reflection substrates and investigated by Fourier transform infrared (FTIR) spectroscopy. Polarization measurements indicate that the orientation of the NMOB molecules is definitely anisotropic with the alkyl tail tilted considerably relative to the surface while the dye chromophore has its plane oriented primarily parallel to the surface. Changes in this orientation upon interleaving these NMOB layers with deuterated cadmium arachidate spacer layers were also investigated both at room and elevated temperatures. © 1991 American Institute of Physics.