Equilibrium configurations and energetics of point defects in two-dimensional colloidal crystals - art. no. 098303

We demonstrate a novel method of introducing point defects (mono- and divac ancies) in a confined monolayer colloidal crystal by manipulating individua l particles with optical tweezers. Digital video microscopy is used to stud y defect dynamics in real space and time. We verify the numerical predictio ns that the stable configurations of the defects have reduced symmetry comp ared to the triangular lattice and discover that in addition they are chara cterized by distinct topological arrangements of the particles in the defec t core. Surprisingly, point defects are thermally excited into separated di slocations, from which we extract the dislocation pair potential.