Relationship of refractive index to mass density and self-consistency of mixing rules for multicomponent mixtures like ambient aerosols
Relationship of refractive index to mass density and self-consistency of mixing rules for multicomponent mixtures like ambient aerosols
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DOI：
10.1016/j.jaerosci.2008.06.006
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发表时间：
2008-11-01
影响因子：
4.5
通讯作者：
Daum, Peter H.
中科院分区：
文献类型：
--
作者：
Liu, Yangang;Daum, Peter H.
本文着重于两个重要的，但解决得不好的方面，环境气溶胶：折射率的关系，质量密度（指数密度关系）和一致性的混合规则，用于计算这两个数量的多组分混合物，如环境气溶胶的指数密度关系。结合经验和理论分析表明，较致密的材料通常倾向于具有较大的折射率，因为所施加的电场诱导了更多数量的电偶极子，并且折射率-密度关系可以通过Lorentz-Lorenz关系合理地描述。结果表明，常用的计算有效质量密度的体积平均混合定则、计算有效折射率的Lorentz-Lorenz混合定则和计算有效折射率的摩尔折射混合定则构成了一组符合Lorentz-Lorenz关系的混合定则。的摩尔分数混合规则和洛伦兹-洛伦兹混合规则被证明是等价的洛伦兹-洛伦兹混合物，而线性体积混合规则是近似的洛伦兹-洛伦兹混合规则的准均匀的混合物，其中的组分的折射率没有太大的不同。研究结果表明，计算气溶胶有效折射率和质量密度的混合规则必须与折射率-密度关系保持一致，这不仅为合理选择计算气溶胶有效性质的混合规则提供了理论指导，而且对发展适用于多个量的有效介质理论提出了新的挑战。从公布的数据，气溶胶粒子的有效比折射率的有效质量密度的经验幂律表达式。(C)2008爱思唯尔有限公司保留所有权利。
This paper focuses on two important yet poorly addressed aspects of ambient aerosols: relationship of refractive index to mass density (index-density relationship) and consistency of the mixing rules used to calculate these two quantities of a multicomponent mixture like ambient aerosols with the index-density relationship. Combined empirical and theoretical analyses show that a denser material generally tends to have a larger refraction index because the applied electric field induces a greater number of electric dipoles, and that the index-density relationship can be described reasonably well by the Lorentz-Lorenz relation. It is shown that the commonly used volume-mean mixing rule for calculating the effective mass density, the Lorentz-Lorenz mixing rule and the molar refraction mixing rule for calculating effective refractive index form a set of mixing rules that are consistent with the Lorentz-Lorenz relation. The molar fraction mixing rule and the Lorentz-Lorenz mixing rule are shown to be equivalent for the Lorentz-Lorenz mixture while the linear volume-mixing rule is an approximation of the Lorentz-Lorenz mixing rule for quasi-homogeneous mixtures wherein the refractive indices of the constituents do not differ much. The results highlight the need for consistency of the mixing rules for calculating the effective refractive index and mass density with the index-density relationship, which not only provides a theoretical guide for judiciously choosing the mixing rules to calculate effective properties of ambient aerosols but also poses new challenges to develop an effective medium theory that applies to more than one quantity. An empirical power-law expression is obtained from the published data that relates the effective specific refractive index to the effective mass density of aerosol particles. (C) 2008 Elsevier Ltd. All rights reserved.