Josh Hansen and Ann Jennings
University of Minnesota
Methods of Experimental Physics Spring 2012
This experiment examined the use of dynamic light scattering using nano-sized polystyrene spheres undergoing Brownian motion. The goal was to determine the translation diffusion constant and compare it to the theoretical Stokes-Einstein relationship. By analyzing the power spectrum, the half width half max was given as G, which is proportional to the diffusion constant, D. When the data was plotted as G versus diameter, the experimental results showed a -1.61s difference from theory. G is proportional to the inverse of the diameter of the spheres. The theoretical Gd=(2.77±0.063)x105nm/s. The experimental Gd=(2.63±0.059)x105nm/s.