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 μ and the second hyperpolarizability γ do not have to be independently determined to obtain the first hyperpolarizability β. 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 β of 23×10−30 esu for para-nitroaniline (PNA), 105×10−30 esu for 4-methoxy-4′-nitrostilbene (MONS), and 95×10−30 esu for 4-hydroxy-4′-nitrostilbene (HONS) dissolved in chloroform have been obtained.