Visualization & Sizing of Soot in Engine Oils

This note presents a technique which looks at the light scattered from individual nanoparticles as they move under Brownian motion in the path of a laser beam. The speed at which the particles move is related to particle size, temperature and solvent viscosity. With knowledge of the temperature and solvent viscosity, particle size can be directly calculated. Here the technique is used to size soot and additive particles in engine oils following suitable sample dilution.