AGGREGATION STRUCTURE AND 2ND-ORDER NONLINEAR OPTICAL EFFECTS IN NONCENTROSYMMETRIC LB FILM OF PHENYLPYRAZINE DERIVATIVE

Molecular hyperpolarizability (β) of 5-p-dodecyloxyphenyl)pyrazine-2-carboxylic acid (C12 PPy), and aggregation structure and second-order nonlinear optical properties in noncentrosymmetric Langmuir-Blodgett films of C 12 PPy were investigated. From the two level model, the value of C12 PPy was estimated to be 26 × 10-30 esu. The large value is comparable to that of p-nitroaniline. By the alternating deposition of C 12 PPy monolayers and barium icosanoate monolayers, we succeeded in the preparation of noncentrosymmetric C12 PPy LB films with enough thickness to be applied to a nonlinear optical waveguide. From the analysis of X-ray diffraction and second-harmonic generation measurements, it was proved that C12 PPy molecules were oriented at about 30° with respect to the normal axis of the noncentrosymmetric LB films. Further, the LB films were demonstrated to possess the large value of second-order nonlinear susceptibility (l×l0-7esu). © 1990, The Chemical Society of Japan. All rights reserved.