Dynamic Light Scattering Data Processing: User Independent or User Driven Algorithms

Dynamic light scattering is beyond competition when measuring particle size in dispersions ranging from nanometers to micrometers. This method has a serious problem in processing experimental data. Instrument noise and polydispersity of the sample lead to the situation when one autocorrelation function corresponds to several different particle size distributions. Often a scientist may not be suspicious of possible other solutions, having one result from a program. I demonstrate the problem on model and experimental data using three known programs: CONTIN, Malvern Zetasizer and DynaLS. I also use my own free program Autocor, which allows to test our own hypotheses about the modality and shape of the particle size distribution by optimizing parameters of the model with a small number of adjustable parameters. The results show the feasibility of a "model based" or "user driven" approach when the raw DLS data are ambiguous or the particle size distribution seems questionable.