Amphiphilic dyes for nonlinear optics: Dependence of second harmonic generation on functional group substitution

Communication: Orientation of chromophores by using the Langmuir‐Blodgett film‐prepration procedure, to a degree practically impossible to achieve by poling in polymer matrices in an electric field, has held to materials exhibiting the highest values of the second order susceptibility (χ (2) ) yet known. The effect of different functional groups in both phenylhydrazone and stryrylpyridinium compounds on both molecular nonlinearity and order in the films the factors which most strongly influence (χ (2) ) has been investigated and a thioether substituent is found to increas (χ (2) ) significantly.