  We report detailed nucleation studies on the liquid-to-solid transition of
hexadecane using nearly monodisperse hexadecane-in-water emulsions. A careful
consideration of the kinetics of isothermal and nonisothermal freezing show
deviations from predictions of classical nucleation theory, if one assumes that
the emulsion droplet population is homogeneous. Similar deviations have been
observed previously. As an explanation, we propose a novel argument based on
the dynamic generation of droplet heterogeneity mediated by mobile impurities.
This proposal is in excellent agreement with existing data.

Soft Condensed Matter;Materials Science