Two-Dimensional Clusters of Colloidal Spheres: Ground States, Excited States, and Structural Rearrangements
| Autor: | Michael B. Brenner, Rebecca W. Perry, Vinothan N. Manoharan, Miranda Holmes-Cerfon |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Physics
Statistical Mechanics (cond-mat.stat-mech) Degenerate energy levels General Physics and Astronomy FOS: Physical sciences 02 engineering and technology Soft modes Condensed Matter - Soft Condensed Matter 021001 nanoscience & nanotechnology Curvature 01 natural sciences 3. Good health Colloid Excited state 0103 physical sciences Soft Condensed Matter (cond-mat.soft) SPHERES Configuration space Atomic physics 010306 general physics 0210 nano-technology Low symmetry Condensed Matter - Statistical Mechanics |
| Popis: | We study experimentally what is arguably the simplest yet non-trivial colloidal system: two-dimensional clusters of 6 spherical particles bound by depletion interactions. These clusters have multiple, degenerate ground states whose equilibrium distribution is determined by entropic factors, principally the symmetry. We observe the equilibrium rearrangements between ground states as well as all of the low-lying excited states. In contrast to the ground states, the excited states have soft modes and low symmetry, and their occupation probabilities depend on the size of the configuration space reached through internal degrees of freedom, as well as a single "sticky parameter" encapsulating the depth and curvature of the potential. Using a geometrical model that accounts for the entropy of the soft modes and the diffusion rates along them, we accurately reproduce the measured rearrangement rates. The success of this model, which requires no fitting parameters or measurements of the potential, shows that the free-energy landscape of colloidal systems and the dynamics it governs can be understood geometrically. 13 pages, 6 figures, 3 tables |
| Databáze: | OpenAIRE |
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