Velocity distributions of camphor particle ensembles

The spatial distribution of ensembles of camphor particles on a water surface can be classified into four phases with the following properties, for increasing density: (I) no clustering of particles and a minimum distance distribution similar to that of a 2D ideal gas; (II) reminiscent of a gas with clustering of particles; (III) net-like structure with occasional rearrangements; and (IV) motionless. While single particles have varying velocity distributions, the overall velocity distribution is Laplacian (the width decreasing with increasing camphor density) for all phases.