利用 T矩阵模型计算水体中非球形悬浮颗粒物光散射特性

摘要

Scattering light properties of suspended particles in water is an important parameter which influences the accuracy of water quality measurement .In this paper ,based on T matrix model ,the authors study the UV‐Visible light irradiation intensity of 3 kinds of non‐spherical suspended particles including ellipsoid ,cylinder and generalized Chebyshev in water .The relationship between light scattering intensity and incident light wavelength ,shape parameters of suspended particles ,complex refractive in‐dex and rotation angle has been presented in detail .Simulation results show that when changing the particle size ,adjusting the wavelength of incident light ,all light scattering intensity of 3 kinds of non‐spherical suspended particles show significant chan‐ges .In the wavelength range from 200~800 nm ,the impact of geometric on the particles size decreases with increasing wave‐length and the sattering properites mainly depends on complex refractive index .The scattering intensity becomes stronger and exhibits strong oscillations for ultraviolet and infrared light when the diameter of particles are less than 0.2μm or approaching 1μm .However ,the scattering intensity is relatively stable and close to zero ,shows small disturbances with the change of wave‐length of incident light when the particles sizes are within 0.3 to 0.9 μm.%水体中悬浮颗粒物的光散射特性是影响基于直接光谱法水质检测结果准确性的一个重要参数。依据 T矩阵模型，研究了紫外‐可见光照射下水体中非球形悬浮颗粒物的光散射强度特性。以藻类和泥沙类颗粒物为例，构造了椭球、圆柱和广义Chebyshev三种非球形粒子光散射模型，分析了入射光波长、悬浮颗粒物形状、复折射率与相对散射光强之间的关系，计算了不同悬浮颗粒物相对散射光强随波长、颗粒物尺寸以及旋转角变化的情况。数值仿真结果表明，不同种类非球形悬浮颗粒物的散射光强度均呈现出显著的变化。在200～800 nm波长范围内，随入射波长的增大，粒子几何尺寸所带来影响逐渐减小，散射特性主要由复折射率决定。当粒子尺寸小于0.2μm或接近1μm时，在入射光波长位于紫外或红外的条件下，散射光强度较大且呈现强烈振荡；而当粒子尺寸 r＝0.3～0.9μm ，散射强度较稳定，接近于0且受到入射光波长的干扰较小。这可为提高紫外‐可见吸收光谱法的检测精度、抑制散射干扰提供一定依据。