  In this article we report on a study of the near-wall dynamics of suspended
colloidal hard spheres over a broad range of volume fractions. We present a
thorough comparison of experimental data with predictions based on a virial
approximation and simulation results. We find that the virial approach
describes the experimental data reasonably well up to a volume fraction of
$\phi=0.25$ which provides us with a fast and non-costly tool for the analysis
and prediction of Evanescent Wave DLS data. Based on this we propose a new
method to assess the near-wall self-diffusion at elevated density. Here, we
qualitatively confirm earlier results [Michailidou et al., Phys. Rev. Lett.,
2009, 102, 068302], which indicate that many-particle hydrodynamic interactions
are diminished by the presence of the wall at increasing volume fractions as
compared to bulk dynamics. Beyond this finding we show that this diminishment
is different for the particle motion normal and parallel to the wall.
