Direct Observation of Rotational Brownian Motion of Spheres by NMR

Abstract
We present a new NMR method for the investigation of rotational Brownian motion based on the appearance of dipolar relaxation as the particles rotate. Our experimental results obtained on submicrometer polystyrene spheres in water confirm quantitatively the basic laws of rotational Brownian motion. The effects of hydrodynamic interactions and long-time tails are discussed.