Redefining Cumulant Analysis in Dynamic Light Scattering for Multimodal and Highly Polydisperse Colloidal Systems

Dynamic Light Scattering (DLS) is a cornerstone technique for characterizing colloidal systems, with cumulant analysis widely used for its simplicity and reproducibility. However, the utility of cumulant analysis is limited to monodisperse or modestly polydisperse samples featuring simple autocorrelation functions. Here, we present an innovative method for cumulant analysis that overcomes these constraints, enabling the characterization of multimodal and highly polydisperse systems exhibiting arbitrarily complex autocorrelation functions. Our method avoids cumulant truncation by applying an analytical form with all cumulants embedded. Verified on synthetic data and validated with experimental analysis, our method retains the elegant, minimalistic principle of the original approach while unlocking its full potential. Our redefined cumulant analysis, therefore, solves a problem that has persisted for over 30 years.