  The adsorption dynamics of a colloidal particle at a fluid interface is
studied theoretically and numerically, documenting distinctly different
relaxation regimes. The adsorption of a perfectly smooth particle is
characterized by a fast exponential relaxation to thermodynamic equilibrium
where the interfacial free energy has a minimum. The short relaxation time is
given by the ratio of viscous damping to capillary forces. Physical and/or
chemical heterogeneities in a colloidal system, however, can result in multiple
minima of the free energy giving rise to metastability. In the presence of
metastable states we observe a crossover to a slow logarithmic relaxation
reminiscent of physical aging in glassy systems. The long relaxation time is
determined by the thermally-activated escape rate from metastable states.
Analytical expressions derived in this work yield quantitative agreement with
molecular dynamics simulations and recent experimental observations. This work
provides new insights on the adsorption dynamics of colloidal particles at
fluid interfaces.
