Light-driven self-healing of nanoparticle-based metamolecules.

Metamolecules and crystals consisting of nanoscale building blocks offer rich models to study colloidal chemistry, materials science and soft matter. Here we demonstrate the self-assembly of colloidal Ag nanoparticles into quasi-one-dimensional metamolecules with intriguing self-healing ability in a linearly polarized optical field. By investigating the spatial stability of the metamolecules, we find that the origin of self-healing is the inhomogeneous interparticle electrodynamic interactions enhanced by the formation of unusual nanoparticle dimers, which minimize the free energy of the whole structures. The equilibrium structures and self-healing behaviors can be further tuned by modifying the electrical double layers surrounding the nanoparticles. Our results reveal a unique route to build self-healing colloidal structures assembled from simple metal nanoparticles, which can potentially lead to reconfigurable plasmonic devices for photonic and sensing applications.