Abstract
Optical microscopy and multi-particle tracking are used to study the short-time self-diffusion of weakly charged silica spheres at a water-air interface. The measured short-time self-diffusion coefficient DSS has the form, DSS/D0=α(1−βn), where n is the area fraction occupied by the particles and D0 is the Stokes-Einstein diffusion coefficient of individual particles in the bulk fluid. The obtained values of α and β differ from those obtained for bulk suspensions, indicating that hydrodynamic interactions between the interfacial particles have interesting new features when compared with their three-dimensional counterpart.
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