STEPWISE COLLOIDAL CRYSTALLIZATION DUE TO CONFINED THERMAL LATTICE VIBRATIONS

Abstract

Discrete colloidal self-assembly (CSA) was observed in the meniscus of a sessile drop of polystyrene latex at low electrolyte concentrations below 10-3 Molar. An energy model that accounts for harmonic lattice vibrations was developed to explain this phenomenon. It was found that due to the relatively small length scale thus confinement of the colloidal crystal, the vibration energy oscillates as inter-particle distance or lattice constant changes. Theoretical analysis shows that the energy dips on the plot of energy versus inter-particle distance well match the discrete steps observed from the experimental results.