We investigate the Brownian motion of hard-sphere colloids near
a solid wall by Evanescent Wave Dynamic Light Scattering (EWDLS).
We carried out measurements for various volume fractions of
sterically stabilized poly(methyl methacrylate) (PMMA) particles
over a range of scattering wave vectors,
q.
While in the dilute regime, the near wall short-time diffusion is
significantly slowed down due to particle-wall hydrodynamic
interactions (HI); as volume fraction increases, the wall effect
is progressively diminished at all
q‘s.

From:
V.N. Michailidou, G. Petekidis, J.W. Swan, and J.F. Brady,
“Dynamics
of Concentrated Hard-Sphere Colloids Near a Wall,”
Physical Review Letters
102, 068302, (2009).