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To obtain exact AFM surface images of colloidal particles with dimensions at most several to 10 times the diameters of the probe tip apexes, it is essential to closely pack the particles in order. We prepared monodisperse, square-prismic colloidal β-FeOOH particles from FeCl3 solutions and found that smectic ordering quickly occurs over a wide region from evaporating suspensions of the particles on substrates. Surface images of the ordered particles clearly showed various shapes of islands with a minimal step height of 1.09 nm, in good agreement with a cell constant by X-ray diffraction, but no spiral steps, suggesting 2D-nucleus formation and subsequent lateral growth of molecular layers on the colloid surfaces. Characteristic striped and one-stepped surfaces were also observed.

We synthesize monodisperse selenium (Se) colloidal rods, and the suspensions exhibit the smectic phase at a particle volume fraction (phi) of 0.28. Side-by-side rod clustering occurs at phi0.04. Cluster-size distributions and persistence times are determined for various phi. In dense suspensions (phi0.1), individual rods reveal characteristic fundamental motions, e.g., reptation and synchronized rotation. Mean-square displacements of the rods suggest a cage trapping and escape. Estimated translational and rotational diffusion coefficients show a large difference from predictions by computer simulations.