Hyper-Rayleigh scattering in solution is used for the determination of the hyperpolarizability of nonlinear optical molecules. Obtaining the first hyperpolarizability β without having to independently determine the dipole moment μ and the second hyperpolarizability γ is an advantage over the electric-field-induced second-harmonic generation technique. Values of the first hyperpolarizability β of 23×${10}^{\mathrm{-}30}$ esu for para-nitroaniline, 105×${10}^{\mathrm{-}30}$ esu for 4-methoxy-4’-nitrostilbene, and 95×${10}^{\mathrm{-}30}$ esu for 4-hydroxy-4’-nitrostilbene dissolved in chloroform have been obtained. The equivalent-internal-field model is shown to hold for small saturated molecules.

• Received 19 December 1990

DOI:https://doi.org/10.1103/PhysRevLett.66.2980