Data acquisition and analysis

Collecting Scattered Light Intensity Data: - The intensity of scattered light is recorded over time, capturing fluctuations due to particle Brownian motion. The data is typically collected for several seconds to minutes, depending on the sample.

Calculating the Autocorrelation Function: - The time correlation function of the scattered light intensity is computed, which decays over time. The rate of decay is related to the particle diffusion coefficient.

Graph illustrating the autocorrelation function decay for monodisperse and polydisperse samples. Show the differences in decay rates and how they relate to particle size distribution.

Determining the Diffusion Coefficient: - The autocorrelation function is analyzed to extract the diffusion coefficient (D). For monodisperse samples, this involves fitting a single exponential decay. For polydisperse samples, multiple exponential decays are fitted.

Converting Diffusion Coefficient to Particle Size: - Using the Stokes-Einstein equation, the diffusion coefficient is converted to the hydrodynamic diameter (D_H). The viscosity of the solvent and the temperature must be known accurately.

Data Interpretation: - Monodisperse samples show a single peak in the size distribution, while polydisperse samples show multiple peaks. - The polydispersity index (PDI) provides a measure of the sample's size distribution width. A low PDI (<0.1) indicates a monodisperse sample, while a high PDI (>0.1) indicates polydispersity.

Software Tools: - Software tools such as Malvern Zetasizer, Brookhaven Instruments, and Horiba DLS software are used for data analysis. These tools provide graphical representations of size distributions and various statistical parameters.