Long range correlation of molecular orientation and vibration in liquid CDCl3

Abstract

The polarization dependence of hyper-Rayleigh second harmonic light scattering (SHS) and hyper-Raman light scattering (HRS) measured for liquid CDCl3 show the effect of long-range correlation of molecular orientation and vibration. HRS from the ν1, ν4, and ν5 vibration modes is polarized transverse to the scattering wavevector, whereas HRS from the ν2, ν3, and ν6 vibration modes and SHS from the ν0 orientation mode all show longitudinal polarization. The transverse polarized HRS is accounted for by long range vibration correlation due to dipole–dipole interaction for molecules at 20–400 nm separation. Longitudinal SHS and HRS are due to the combined effect of long range dipole–dipole orientation correlation and the increment in the molecular first hyperpolarizability induced by short range intermolecular interactions.