A Quick Method to determine ensemble averaged Translational and Rotational Diffusion coefficients

The ensemble averaged translational diffusion of isotropic particles and coupled translational-rotational diffusion of anisotropic particles inside water and various polymer solutions were determined using dynamic differential microscopy (DDM). Initially, we applied this technique to characterize the dynamics of 25 nm radius particles within entangled high molecular weight, M_w=600 kg/mol polyethylene oxide-water solutions, which extended the scope of DDM to study the dynamics and rheological properties of soft matter at nanoscale. We will demonstrate the application of this method to characterize the motion of colloidal ellipsoids of different aspect ratios.