Colloidal crystals: Structure, dynamics, and the importance of dimer bonds

Colloidal crystals, periodic arrays of micron-sized solid particles in solution, offer a unique glimpse of the particle-scale structures and dynamics within a true thermodynamic ensemble. Experimental colloidal studies of melting and crystallization [55, 56, 13, 76, 2] as well as non-equilibrium states such as colloidal glasses [67, 68, 29, 49] have uncovered numerous mechanisms that are experimentally inaccessible in atomic systems due to both small timescales and small lengthscales. The great successes of colloidal physics have emerged as a result of technological advances enabling synthesis of large batches of monodisperse spherical particles. Yet, the crystal structures formed by such particles are limited to variations on layers of close-packed spheres. Consequently, one of the current frontiers in colloidal physics is the study of novel crystal structures formed by non-spherical particles.;My thesis work has focused on crystals formed by colloidal dimer particles consisting of two connected spherical lobes. Surprisingly, while the structure of two dimensional crystals formed by the dimers are quite similar to those observed for spheres, the motion of defects within the dimer crystals is significantly different. Geometric obstacles formed by interlocking dimers restrict the motion of defects and ultimately introduce a completely unexpected, previously unreported glassy defect dynamics within a colloidal crystal.