Short-time dynamics of colloidal particles confined between two walls Article uri icon

abstract

  • The short-time dynamics of colloidal particles in a quasi-two-dimensional geometry is studied by digital video microscopy. The particles (polystyrene spheres) are suspended in water and confined between two parallel glass plates, forming an effective two-dimensional system. The (effective) two-dimensional van Hove function [formula presented] and its self and distinct part are measured with a time resolution of 1/30 s. We found that the general behavior of these time-correlation functions (and their Fourier transforms) is quite similar to that of their three-dimensional counterparts. The effects of the strong hydrodynamic coupling of the particles motion to the walls and that due to the hydrodynamic interactions between particles are contained in the (effective) hydrodynamic function [formula presented] obtained from the initial slope of [formula presented] [the Fourier transform of [formula presented] We found that [formula presented] as a function of the wave vector k and particle concentration, exhibits a similar qualitative behavior to the hydrodynamic function in homogeneous three-dimensional suspensions of hard spheres. We also found in our systems that the particle fluctuations relax only by self-diffusion for wave vectors where the static structure factor [formula presented] This result is important for measurements of self-diffusion dynamics in three-dimensional systems by light scattering techniques. © 2002 The American Physical Society.

publication date

  • 2002-01-01