Colloidal Particles at Water-Glass Interface: Analyzing Videomicroscopic Data.

Direct videomicroscopic observations provide a powerful tool for investigations on the deposition of colloidal particles at liquid-solid interfaces. However, the technique is also capable of producing artefacts caused mainly by limited resolution. In the present contribution we discuss the possibilities and limitations of videomicroscopic observations, focussing thereby on an application example, namely particle deposition from flow in a parallel plate channel in the presence of a repulsive barrier. We outline algorithms for the determination of the relevant quantities, indicate the pitfalls, and provide correction formulas. Special attention is paid to the kinetics of particle release, namely to the accurate determination of the distribution of the times the particles spend adhering to the surface. In our example the kinetics of the release is found to be highly nonexponential, but an adequate fit of the measured distribution of adhesion times is obtained with a stretched exponential exp[-(betatau)nu], where nu approximately 0.5 and beta approximately 3 x 10(-5) s-1. Copyright 1998 Academic Press.