Second-order non-linear optical effects in Langmuir-Blodgett films

The synthesis of a new series of amphiphilic dyes of the form R¹R²NC₆H₄CH=CHC₅H₄⁺NCH₂CH₂COO^- (R¹=R²=C₆H₁₃,C₁₀H₂₁,C₁₄H₂₉ and C₁₈H₃₇) is described. These dyes have two alkyl chains per chromophore so as to facilitate fast deposition of Langmuir-Blodgett films. We report on the fabrication of monolayer films of these materials and the measurement of optical second harmonic generation in them. We deduce information about molecular tilt orientations and hyperpolarizabilities and compare the latter with previously published values of the electro-optic coefficients.