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Determining the Liquid Light Scattering Cross Section and Depolarization Spectra Using Polarized Resonance Synchronous Spectroscopy
journal contribution
posted on 2017-11-08, 00:00 authored by Sumudu
A. Athukorale, Yadong Zhou, Shengli Zou, Dongmao ZhangRayleigh
scattering is a universal material property because all
materials have nonzero polarizability. Reliable quantification of
the material light scattering cross section in the liquid phase and
its depolarization spectra is, however, challenging due to a host
of sample and instrument issues. Using the recently developed polarized
resonance synchronous spectroscopic method, we reported the light
scattering cross section and depolarization spectra measured for a
total of 29 liquids including water, methanol, ethanol, 1-propanol,
1-butanol, dimethylformamide, carbon disulfide, dimethyl sulfoxide,
hexane and two hexane isomers (3-methylpentane and 2,3-dimethylbutane),
tetrahydrofuran, cyclohexane, acetonitrile, pyridine, chloromethanes
including di-, tri, tetrachloromethane, acetone, benzene and eight
benzene derivatives (toluene, fluorobenzene, 1,2-, 1,3-, and 1,4-difluorobenzene,
chlorobenzene, 1,2- and 1,3-dichlorobenzene, and nitrobenzene). The
solvent light scattering depolarization is wavelength-independent
for the model solvents, and it varies from 0.023 ± 0.011 for
CCl4 to 0.619 ± 0.022 for nitrobenzene. The light
scattering cross-section spectra can be approximated with the function
of σ(λ) = αλ–4 with the
α value varying from 7.2 ± 0.2 × 10–45 cm6 for water to a maximum of 8.5 ± 0.6 × 10–43 cm6 for nitrobenzene. Structural isomerization
has no significant effect on either the depolarization or the scattering
cross sections for both hexanes and difluorobenzene isomers. This
work represents the most comprehensive experimental study on liquid
light scattering features. The insight from this work should be important
for understanding the correlation between the material structure and
optical properties. The described method can be readily implemented
by researchers with access to conventional spectrofluorometers equipped
with excitation and detection polarizers.