Dynamic light scattering by permanent gels: heterodyne and nonergodic medium methods of data evaluation

Abstract

Four relationships between the intensity and field correlation functions are used in the analysis of measured intensity correlation functions in dynamic light scattering with data obtained for four different polymer gel samples. The evaluation of diffusion coefficients has been performed using inverse Laplace transformation (ILT) and the cumulants method, respectively. Diffusion coefficients derived from the nonergodic medium method are almost the same as those from the heterodyne method when ILT is used. ILT gives similar results by all four procedures even when large baselines exist, whereas the cumulants method leads to incorrect diffusion coefficients from the correlation function derived using the nonergodic medium method