IR analysis of Langmuir-Blodgett films for nonlinear optics

Abstract From polarized IR spectra of DCANP and four N -alkyl homologues, the dichroic ratios of the NH, the antisymmetric ( v a ) and symmetric ( v a ) CH 2 vibrational absorptions are calculated and compared to reported results from polarized UV spectra. The orientation of the NH group in most pronounced for the n = 26 homologue. Similarly the CH 2 chains tend to be more regularly oriented with increasing length. The increasing order of the chromophores explains the increase in the second order susceptibilities for the homologues with n = 18, 20 and 22 carbon atoms in the chain.