Analyzing Depolarized Dynamic Light Scattering by Solutions of Elongated Particles

Using Depolarized Dynamic Light Scattering (DDLS) to study structure and dynamics of geometrically anisotropic nanoparticles in solution requires good quality intensity correlation data collected at a range of angles and concentrations and careful consideration of appropriate assumptions and various geometrical models. This project is aimed to analyze the effectiveness of different approaches to DDLS data analysis and use of appropriate assumptions for the solutions of geometrically anisotropic nanoparticles. The focus was on three geometrical models: de la Torre's straight cylinder, Perrin's prolate ellipsoid, and Martchenko et. al.’s spherocylinder and on two different approaches to data analysis. In the first approach, the angular dependence of relaxation decay rates of measured intensity correlation functions was used to obtain translational and rotational diffusion coefficients of the system that were then used for finding the geometrical anisotropy of the particles for a given model. In the second approach, a single scattering angle correlation functions were analyzed, and their decay rates used to solve for particle dimensions using the same geometrical models. Both approaches and the three geometrical models were tested on the DDLS data on aqueous solutions of gold nanorods (AuNRs). The conclusions on the applicability and limitations of each approach for various geometrical models will be presented.