动态光散射最优拟合累积分析法

Optimal Fitting Cumulants Method for Dynamic Light Scattering

动态光散射是测量纳米颗粒大小的有效方法,但使用线性累积分析法反演的颗粒直径受数据点长度的影响较大,数据点长度不同,拟合结果也不同。针对线性累积分析法的缺点,对比分析了线性和非线性累积分析法,并结合两者的优点提出最优拟合累积分析法。此算法由一阶曲线拟合反演颗粒的直径,并与一阶多项式拟合结果对比,获得光强自相关函数的最优线性拟合长度,然后由二阶多项式拟合反演颗粒的多分散系数。理论分析与实验数据表明:最优拟合累积分析法反演的颗粒直径相对误差和重复性均小于2%,多分散系数相对误差小于6%,因此利用最优拟合累积分析法可获得稳定、可靠的颗粒直径及其多分散系数。

Dynamic light scattering is a powerful tool for measuring the size of nanoscale particles. However, the average particle size inverted by the traditional linear cumulants method depends closely on the length of correlation data. Linear and non-linear fitting algorithms are analyzed in order to overcome this disadvantage. An optimized fitting algorithm for the cumulants method is proposed based on the advantages of both fitting algorithms. The particle diameter is obtained from a first-order curve fit, and the particle distribution′s polydispersity from a second-order polynomial fit over the optimal range of the intensity correlation function. Theoretical analysis and experimental data show that the relative error and repeatability of the inverted diameter are less than 2%, and the relative error of polydispersity index is less than 6%. In conclusion, the optimal fitting algorithm for the cumulants method can be used to measure a stable and reliable particle size and its polydispersity index.