Orientation correlation and local field in liquid nitrobenzene.

Hyper-Rayleigh scattering (HRS) is sensitive to long-range molecular orientation correlation in isotropic liquids composed of dipolar molecules. Measurements of the polarization, angle, and spectral dependence for HRS from liquid nitrobenzene (NB) are analyzed to determine the NB molecular orientation correlations at long range. The longitudinal and transverse orientation correlation functions for r > 3 nm are BL(r) = (a/r)(3) and BT(r) = - BL(r)/2, where a = 0.20 ± 0.01 nm. Measurements of HRS induced by dissolved ions are also analyzed and combined with molecular dynamics simulation and dielectric response results, to determine the molecular dipole moment μ = 3.90 ± 0.04 D, Kirkwood orientation correlation factor gK = 0.68 ± 0.02, and local field factor f(0) = 0.85 ± 0.04 × Onsager local field factor in liquid nitrobenzene.