Characterizing Nanoparticle Size by Dynamic Light Scattering

The Dynamic Light Scattering (DLS) Technique was used to determine the size, shape and diffusion coefficient of rod-like nanoparticles. The intensity auto-correlation functions of light scattered by particles in a solution were measured and analyzed to obtain the relaxation rates for decay of intensity correlations. These decay rates are related to the diffusion coefficients pertaining to the motion of the particle. In the case of nanorods, there are two types of motion - translational and rotational. By disentangling the relaxation rates, corresponding to these two types of motion, the shape and size of nanoparticles were characterized. These experiments, though limited in scope, demonstrate the promise of dynamical light scattering as an inexpensive and convenient technique for characterizing regular shaped nanoparticles in a fluid medium as well as the capability of DLS to distinguish nanoparticle shapes with smaller aspect ratios