Determination of the Translational and Rotational Diffusion Coefficients of Rodlike Particles Using Depolarized Dynamic Light Scattering

Depolarized dynamic light scattering (DDLS) experiments are reported on three different systems: on tobacco mosaic virus as a well investigated sample; on PEO−PPO−PEO triblock copolymer micelles, which show sphere-to-rod transition with increasing temperature; and on a microemulsion of the type water/octane/CiEj. DDLS measurements were performed using highly discriminating polarizers and single-mode fiber detection at different scattering angles, obtaining decay rates ΓVH versus scattering angle. The rotational and translational diffusion coefficients available from these plots were taken to evaluate size parameters of the systems using Broersma's expressions for a stiff rod. Good agreement with theory and literature was found in the case of tobacco mosaic virus and at concentrations below the overlap concentration c* for the other two systems.