Athukorale Sumudu A, Zhou Yadong, Zou Shengli, Zhang Dongmao
Department of Chemistry, Mississippi State University , Mississippi State, Mississippi 39762, United States.
Department of Chemistry, University of Central Florida , Orlando, Florida 32816, United States.
Anal Chem. 2017 Dec 5;89(23):12705-12712. doi: 10.1021/acs.analchem.7b02721. Epub 2017 Nov 20.
Rayleigh 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 CCl to 0.619 ± 0.022 for nitrobenzene. The light scattering cross-section spectra can be approximated with the function of σ(λ) = αλ with the α value varying from 7.2 ± 0.2 × 10 cm for water to a maximum of 8.5 ± 0.6 × 10 cm 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.
瑞利散射是一种普遍的材料特性，因为所有材料都具有非零极化率。然而，由于一系列样品和仪器问题，可靠地定量液相中材料的光散射截面及其去极化光谱具有挑战性。利用最近开发的偏振共振同步光谱方法，我们报告了总共29种液体的光散射截面和去极化光谱，这些液体包括水、甲醇、乙醇、1-丙醇、1-丁醇、二甲基甲酰胺、二硫化碳、二甲基亚砜、己烷和两种己烷异构体（3-甲基戊烷和2,3-二甲基丁烷）、四氢呋喃、环己烷、乙腈、吡啶、氯甲烷（包括二氯甲烷、三氯甲烷、四氯化碳）、丙酮、苯和八种苯衍生物（甲苯、氟苯、1,2-、1,3-和1,4-二氟苯、氯苯、1,2-和1,3-二氯苯以及硝基苯）。对于模型溶剂，溶剂光散射去极化与波长无关，其范围从四氯化碳的0.023±0.011到硝基苯的0.619±0.022。光散射截面光谱可以用函数σ(λ)=αλ近似，α值从水的7.2±0.2×10⁻²⁰cm变化到硝基苯的最大值8.5±0.6×10⁻²⁰cm。结构异构化对己烷和二氟苯异构体的去极化或散射截面均无显著影响。这项工作代表了对液体光散射特性最全面的实验研究。这项工作的见解对于理解材料结构与光学性质之间的相关性应该很重要。所述方法可以由能够使用配备激发和检测偏振器的传统荧光分光光度计的研究人员轻松实现。
