2ND-ORDER SUSCEPTIBILITY DETERMINATION BY FOURIER-ANALYSIS

The macroscopic tenser components of the nonlinear surface susceptibil ity Chi(s)((2)) of monomolecular organic thin films have been determin ed with high precision using Fourier analysis of signals obtained by p olarization rotation of the incident fundamental radiation. Our analys is clearly shows the presence of three complex-valued susceptibility-t ensor components and hence the inapplicability of Kleinman's conjectur e for a thin him of rotational symmetry around the surface normal. The description of the susceptibility in terms of three tenser components of different phase and magnitude indicates that the usual description within the model of noninteracting rod-like molecules is insufficient to describe the optical nonlinearity of a well-organized Langmuir-Blo dgett-type thin film.