HYPER-RAYLEIGH SCATTERING IN SOLUTION

The experimental setup for the implementation of a new technique to determine the hyperpolarizability of nonlinear optical molecules in solution is presented. The new technique, hyper-Rayleigh scattering in solution [K. Clays and A. Persoons, Phys. Rev. Lett. 66, 2980 (1991)], has the advantage over the electric-field-induced second-harmonic generation technique that the dipole moment-mu and the second hyperpolarizability-gamma do not have to be independently determined to obtain the first hyperpolarizability-beta. No electric field is needed to lower the intrinsic symmetry of the isotropic solution, leading to a simpler cell design and a simpler local field factor. The internal reference method, when applicable, completely eliminates the local field factor. With the technique presented, values of the first hyperpolarizability-beta of 23 X 10(-30) esu for para-nitroaniline (PNA), 105 X 10(-30) esu for 4-methoxy-4'-nitrostilbene (MONS), and 95 X 10(-30) esu for 4-hydroxy-4'-nitrostilbene (HONS) dissolved in chloroform have been obtained.