Long-range orientation correlation in dipolar liquids probed by hyper-Rayleigh scattering.

Area of Science:

• Physical Chemistry
• Molecular Spectroscopy
• Fluid Dynamics

Background:

• Hyper-Rayleigh scattering (HRS) probes molecular orientation correlations in liquids.
• HRS is linked to turbulence models through shared correlation functions.
• Previous studies lacked detailed analysis of HRS in water's orientation dynamics.

Purpose of the Study:

• To analyze the angle and polarization dependence of HRS from water.
• To determine the form of the molecular orientation correlation function in water.
• To connect HRS findings to fluid turbulence theoretical frameworks.

Main Methods:

• Experimental measurement of Hyper-Rayleigh scattering from water.
• Analysis of angle and polarization dependence of scattered light.
• Theoretical modeling of correlation functions based on experimental data.

Main Results:

• A dominant transverse mode contribution was observed in HRS from water.
• This transverse mode's amplitude was independent of the scattering wavevector.
• The long-range molecular orientation correlation function was determined to vary as r(-3±ε).

Conclusions:

• HRS experiments provide strong constraints on water's molecular orientation correlation function.
• The observed transverse mode HRS is consistent with a specific correlation function decay.
• Findings advance understanding of molecular correlations in liquids and their link to turbulence.