Difference between revisions of "The Free Energy Landscape of Hard Sphere Clusters"

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Small numbers of polystyrene (PS) microspheres were placed in cylindrical microwells filled with polyNIPAM nanoparticles (Fig 1A).  
 
Small numbers of polystyrene (PS) microspheres were placed in cylindrical microwells filled with polyNIPAM nanoparticles (Fig 1A).  
  
[[Image:meng_fig1.gif|400px|thumb|Fig. 1. A. Experimental system: microwells filled with polyNIPAM microgel particles and PS microbeads. B. Close-up view of two sticky microspheres and surrounding nanoparticles. C. Pair potential. Note that the depletion attraction is very short-range, so the interaction is strictly pairwise additive. D. Micrograph of several microwells, each with different individual clusters. E. Optical micrographs of colloidal clusters in microwells with N = 2, 3, 4, 5 particles.]]
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[[Image:meng_fig1.gif|400px|thumb|center|Fig. 1. A. Experimental system: microwells filled with polyNIPAM microgel particles and PS microbeads. B. Close-up view of two sticky microspheres and surrounding nanoparticles. C. Pair potential. Note that the depletion attraction is very short-range, so the interaction is strictly pairwise additive. D. Micrograph of several microwells, each with different individual clusters. E. Optical micrographs of colloidal clusters in microwells with N = 2, 3, 4, 5 particles.]]
  
 
== Results ==
 
== Results ==
  
 
== Discussion ==
 
== Discussion ==

Revision as of 03:05, 14 September 2010

Entry by Leon Furchtgott, APP 225 Fall 2010.

The Free-Energy Landscape of Clusters of Attractive Hard Spheres. Meng, G., Arkus, N., Brenner, M. P., & Manoharan, V. N. (2010). Science, 327, 560-563

Summary

The paper is interested in the behavior of small (10 or fewer colloidal particles) clusters and their relation to bulk behavior. In particular, the paper discusses the thermodynamics of small clusters: what structures are favored by entropy or by the potential energy, how this competition changes as N grows larger. Through careful experimentation the authors succeed in measuring structures and free energies of small equilibrium clusters. They compare these structures to theoretical predictions and draw conclusions regarding highly favored configurations.

Experimental Setup

Small numbers of polystyrene (PS) microspheres were placed in cylindrical microwells filled with polyNIPAM nanoparticles (Fig 1A).

Fig. 1. A. Experimental system: microwells filled with polyNIPAM microgel particles and PS microbeads. B. Close-up view of two sticky microspheres and surrounding nanoparticles. C. Pair potential. Note that the depletion attraction is very short-range, so the interaction is strictly pairwise additive. D. Micrograph of several microwells, each with different individual clusters. E. Optical micrographs of colloidal clusters in microwells with N = 2, 3, 4, 5 particles.

Results

Discussion