Abstract: 

Colloidal particles accumulate and organize at fluid interfaces via capillary interactions. We study pair interactions and structure formation around spherical particles with pinned contact lines. Particles attract to apparent contact and organize in near trapped structures that reflect the underlying curvature field. We have derived pair potentials to describe these interactions. The particles distort the surrounding interface in which we calculate the distortion area and hence capillary energy around a colloid and its dependence on proximity to neighbors and on the underlying interface curvature. Dimer formation alignment with respect to principal axes and dynamics compare favorably to prediction. We use this pair potential in Monte Carlo simulations to compare to the structures formed. Extensions to address elongated particles are discussed.