  We used x-ray photon correlation spectroscopy to study the dynamics in the
lamellar phase of a platelet suspension as a function of the particle
concentration. We measured the collective diffusion coefficient along the
director of the phase, over length scales down to the interparticle distance,
and quantified the hydrodynamic interaction between the particles. This
interaction sets in with increasing concentration and can be described
qualitatively by a simplified model. No change in the microscopic structure or
dynamics is observed at the transition between the fluid and the gel-like
lamellar phases.
