气溶胶单粒子的偏振散射特性研究

建立了气溶胶单粒子的偏振散射实验装置,采用T-matrix方法模拟球形粒子和长形粒子的光散射计算, 讨论了偏振强度因子(Pf)和穆勒矩阵元素(Z11、Z12)随粒径、形状的变化关系,结果表明,球形粒子和杆状粒子的Pf和Z12随着粒径的增大存在明显差异。通过对单分散的气溶胶颗粒物样品的实验测量,得到不同样品的Pf值和Z12。实验结果表明,以油酸粒子的Z12为基准, 差值△Z12=12可以作为球形的油酸粒子和长形的核黄素以及石棉纤维的区分阈值, △Z12 介于12~41主要为核黄素粒子, △Z12达到59时粒子可被认为是长形的石棉纤维粒子, 而立方形的NaCl气溶胶粒子的△Z12与油酸粒子非常接近,难以区分。初步实验表明,穆勒矩阵元素Z12可以用于识别长形粒子,该研究为颗粒物形态的偏振测量提供依据。

Investigation of Polarization Scattering Characteristics of Single Particle Aerosols

An experimental device for the polarization scattering of aerosol single particles is developed. The T-matrix method is used to simulate the light scattering calculation of spherical particles and long particles. The relationship between polarization intensity factor (Pf), Muller matrix elements (Z11 and Z12) with particle size and shape is discussed. The results show that, with the increase of particle size, there are significant differences between spherical particles and rod-shaped particles in parameters Pf and Z12. By experimental measurement, Pf values and Z12 of different samples are obtained. The experimental results show that, using the Z12 of oleic particles as the reference, the difference △Z12=12 can be used as the distinguishing threshold for spherical oleic acid particles and ellipsoidal riboflavin particles and long asbestos fibers particles. The△Z12 of riboflavin particles ranges from 12 to 41, and when△Z12 reaches 59, the particles can be considered as asbestos fiber particles. However, it's hard to distinguish cubic NaCl particles and oleic acid particles because the values△Z12 of each are very similar. Preliminary experiments show that Muller matrix element Z12 can be used to identify long particles, which can help to design morphology measurement instrument with polarization method.