Sun, 27 Jul 2008 08:03:38 BST CiteULike: dchen's Yodh http://www.citeulike.org/user/dchen/author/Yodh CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2874159 <i>Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 4. (2008)</i><br /><br />Melting of two-dimensional colloidal crystals is studied by video microscopy. The samples were composed of microgel spheres whose diameters could be temperature tuned, and whose pair potentials were measured to be short ranged and repulsive. We observed two-step melting from the crystal to a hexatic phase and from the hexatic to the liquid phase as a function of the temperature-tunable volume fraction. The translational and orientational susceptibilities enabled us to definitively determine the phase transition points, avoiding ambiguities inherent in other analyses and resolving a “dislocation precursor stage” in the solid phase that some of the traditional analyses may incorrectly associate with the hexatic phase. A prefreezing stage of the liquid with ordered patches was also found. Melting of two-dimensional tunable-diameter colloidal crystals Y Han NY Ha AM Alsayed AG Yodh doi:10.1103/PhysRevE.77.041406 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics), Vol. 77, No. 4. (2008) 2008-06-08T22:54:09-00:00 2008 Physical Review E (Statistical, Nonlinear, and Soft Matter Physics) 77 4 APS 2008 2d colloids crystal liquid microgel pre http://www.citeulike.org/user/dchen/article/2735618 <i>Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 359, No. 1782. (15 May 2001), pp. 921-937.</i><br /><br />In this paper we present fundamental studies elucidating the role of entropy in particle suspensions. We focus on systems composed of large colloidal particles along with a second, usually smaller species such as a particle or polymer. We describe direct measurements of these interactions in suspension, and we systematically show how these forces can be used to control the self-assembly of colloidal particles. The paper provides a unified review of the experiments from our laboratory, and in a few cases touches on very recent results. Entropically driven self-assembly and interaction in suspension Yodh doi:10.1098/rsta.2000.0810 Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 359, No. 1782. (15 May 2001), pp. 921-937. 2008-04-29T23:03:20-00:00 2001 Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 359 1782 921 937 colloids opticaltweezer yodh