Linear and nonlinear optical behaviors of Langmuir Blodgett multilayers of push pull tolan derivatives

Second-harmonic generation together with linear dichroism has been studied on monolayer assemblies of 4-octadecylamino- and 4-docosylamino-4′-nitro-tolan. These amphiphiles form condensed monolayers at the air–water interface. Using the conventional Langmuir–Blodgett and the horizontal lifting methods, we obtained the alternating Y-type and the nonalternating X-type multilayers, respectively, and the considerably anisotropic second-harmonic generation of both types was observed, depending on the dipping direction of solid substrates or the monolayer compression.