Crystals and Liquids in Monolayers of Heavy particles

We use brightfield microscopy to observe a dense monolayer of heavy colloidal particles sedimented to the bottom of a sample chamber. In our system, we control two parameters: particle concentration and Peclet number (Pe). Pe measures the relative importance of the gravitational force over the thermal effects and is directly proportional to the particle diameter. We are trying to find how Pe and particle concentration influence the packing structure of the sedimented monolayer. When we compared our simulation data with our experimental results, we found that our experiments were significantly less ordered than the simulations. This led us to investigate the influence of polydispersity in our samples and experimental issues created by the unintended influence of gravity when the slide has a slight tilt away from the horizontal.