Lights, nano, action! New plasmonic materials and methods to probe nanoscale phenomena

The field of plasmonics has transformed the ability to control nanoscale light-matter interactions with applications ranging from high-efficiency photovoltaic modules to ultrasensitive biodetectors, electromagnetic cloaks, and subwavelength integrated photonic circuits. This article summarizes my group’s efforts to contribute to this burgeoning field, with emphasis on our research in quantum plasmonics and optical-frequency magnetism. First, we explore the plasmon resonances of individual nanoparticles as they transition from a classical to a quantum-influenced regime. We then utilize these results to directly monitor hydrogen absorption and desorption in individual palladium nanocrystals. Subsequently, using real-time manipulation of plasmonic particles, we investigate plasmonic coupling between pairs of particles separated by nanometer- and angstrom-scale gaps. For sufficiently small separations, we observe the effects of quantum tunneling between particles on their plasmonic resonances. Finally, using the properties of coupled metallic nanoparticles, we demonstrate the colloidal synthesis of an isotropic metafluid or “metamaterial paint” that exhibits a strong optical-frequency magnetic response and the potential for negative permeabilities and negative refractive indices.