用动态光散射时间相干度法测量纳米颗粒粒径

Measurement of nanoparticle sizes by variance of temporal coherence of dynamic light scattering

针对传统动态光散射法测量纳米颗粒粒径算法复杂、速度慢、成本高等问题,提出了一种通过改变动态散射光信号时间相干度来测量纳米颗粒粒径的方法,并对其所采用的算法和测量系统进行研究。首先,介绍了动态光散射测量法的基本原理,并引出系统相干度的概念(包括时间相干因子和空间相干因子)。接着,从光电探测器的统计特性出发,通过对光子计数方差的分析得到散射光强波动的方差。然后,建立光强波动的方差与时间相干度的方程,并由该方程得到动态光散射信号的衰减线宽。最后,根据Stokes-Einstein公式计算出纳米颗粒的粒径。对粒径为30,50,100 nm,溶液透光率为96%的乳胶球标准颗粒溶液进行了实验,结果表明:本文提出的测量法其测量均值误差和重复性误差的平均值分别为1.84%和1.76%,满足均值误差和重复性误差小于2%的国标要求。

A measurement method of nanoparticle sizes by the variance of temporal coherence of dynamic light scattering was presented to resolve problems of complex algorithms,slow operation,and high costs of traditional dynamic light scattering nano-particle measurement systems and its algorithm and measurement system were studied,respectively.Firstly,the photon correlation spectroscopic theory of dynamic light scattering measurement was introduced,and the concept of coherence degree which includes a temporal coherence factor and a spatial coherence factor was deduced.Then,based on the statistical properties of photoelectric detectors,the variance of the fluctuation of scattering intensity was deduced through analysis of the variance of photon counting.The equations of the variance of intensity fluctuations and the temporal coherence degree were established,and the decay width of a dynamic light scattering signal was obtained by the equations.Finally,the particle diameters of the nano-particles were calculated by the Stokes-Einstein equation.Furthermore,the latex particle sample solution with the diameters of 30,50,100 nm and the transmission of 96% was used as the standard sample to be tested in an experiment.The results show that the average values of the measurement error and repeatability error of the new method are 1.84% and 1.76%,respectively,which satisfies the national standard that these errors should be less than 2%,respectively.