| Colloidal systems are known to undergo a first order phase transition from the short range ordered fluid state to the crystalline state under isothermal conditions, if the colloidal interactions are adjusted to become sufficiently strong. At the same time the dispersion behaviour can be conveniently observed by optical methods like high resolution video microscopy or time resolved light scattering, yielding information on both individual particles and complete crystals. It is observed that the solidification scenarios differ for different types of interactions. For some situations, however, well defined and metal-analogue nucleation and growth processes are found. Quantitative measurements of velocities in reaction controlled growth or homogeneous nucleation rate densities then may give access to key parameters of solidification like an effective undercooling or (using Classical nucleation theory) to interfacial tensions. On the other hand, the microscopic approach may often allow to characterize specific mechanisms involved in solidification and thus to test assumptions made in phenomenological parameterizations. The talk will focus on experimental issues, but will also discuss the role of model colloids in addressing the fundamentals of solidification. |
|