Department of Engineering Sciences, The Ångström Laboratory, Uppsala University, PO Box 534, SE-75121 Uppsala, Sweden.
Nanoscale. 2019 Apr 11;11(15):7404-7413. doi: 10.1039/c9nr01707k.
Light scattering from small particles exhibit unique angular scattering distributions, which are strongly dependent on the radius to wavelength ratio as well as the refractive index contrast between the particles and the surrounding medium. As the concentration of the particles increases, multiple scattering becomes important. This complicates the description of the angular scattering patterns, and in many cases one has to resort to empirical phase functions. We have measured the angle dependence of light scattering from a polymer layer containing sub-micron metallic and dielectric particles. The samples exhibited strongly forward and backward peaked scattering patterns, which were fitted to a number of empirical approximative phase functions. We found that a novel two-term Reynolds-McCormick (TTRM) phase function gave the best fit to the experimental data in all cases. The feasibility of the TTRM approach was further validated by good agreement with numerical simulations of Mie single scattering phase functions at various wavelengths and sizes, ranging from the Rayleigh scattering regime to the geometrical optics regime. Hence, the widely adaptable TTRM approach is able to describe angular scattering distributions of different kinds of nanospheres and nanocomposites, both in the single scattering and multiple scattering regimes.
从小颗粒散射的光表现出独特的角度散射分布，这强烈依赖于颗粒的半径与波长比以及颗粒与周围介质的折射率对比。随着颗粒浓度的增加，多次散射变得重要。这使得角度散射模式的描述变得复杂，在许多情况下，人们不得不诉诸经验相位函数。我们已经测量了含有亚微米金属和介电颗粒的聚合物层的光散射的角度依赖性。这些样品表现出强烈的前向和后向峰值散射模式，这些模式被拟合到一些经验近似相位函数中。我们发现，一种新的两项雷诺兹-麦考密克（TTRM）相位函数在所有情况下都能最好地拟合实验数据。TTRM 方法的可行性还通过与不同波长和尺寸的 Mie 单散射相位函数的数值模拟的良好一致性得到了进一步验证，范围从瑞利散射区域到几何光学区域。因此，适应性广泛的 TTRM 方法能够描述不同种类的纳米球和纳米复合材料的角度散射分布，无论是在单散射还是多次散射区域。
