This research will employ a technique called total internal reflection microscopy (TIRM) for the measurement of colloidal particle position relative to a flat surface. TIRM is based on measuring the intensity of light scattered by a particle in the evanescent wave region of an otherwise totally reflecting surface. Due to the strong variation of intensity with distance, nanometer resolution is possible. By measuring the time variations of position for a system at equilibrium, one is able to infer the potential energy of interaction or force between the particle and surface as functions of the separation. The technique will be improved and used to deduce electrical double layer forces. The research should provide a new and extremely useful tool for colloid science. It will give a critical evaluation of the theories for colloidal forces. The results will be very important to understanding particle deposition rates and deposition patterns as well as consolidation of green bodies dominated by colloidal forces.
