Effect of non-Gaussian term on dynamic light scattering measurement at ultra-low concentrations

The simulated dynamic light scattering data of particles with different distribution widths were inverted using the methods of removing and retaining the non-Gaussian term. The distribution of particle size information in the intensity autocorrelation function (ACF) of particles with different distribution widths was also obtained by calculating the difference between the intensity ACF of particles with different distribution widths and the intensity ACF corresponding to the average particle size. The results show that the removal and retention of non-Gaussian term for narrow distribution particle systems have no significant impact on the inverted particle size distribution at lower noise levels. As the noise level increases, the performance indices of inversion results by removing non-Gaussian term are better than that by retaining non-Gaussian term. For wide distribution particle systems (coefficients of variation typically greater than 3%), retaining the non-Gaussian term can yield more accurate inversion results. The reason for the above results is that the content of particle size information in the non-Gaussian term corresponding to particles with different distribution widths is different. Compared with narrow distribution particle systems, the non-Gaussian term in the intensity ACF corresponding to wide distribution particle systems contains more particle size information. Removing non-Gaussian term can lead to the loss of some particle size information, thereby reducing the accuracy of the inversion results. Since the long delay period of the intensity ACF contains more noise, the inversion of narrow distributed particles does not benefit from retaining non-Gaussian term, and the accuracy of the inversion results will be reduced due to the increased noise.