Characterizing Plasmons in Nanoparticles and Their Assemblies with Single Particle Spectroscopy

The plasmonic properties of noble-metal nanoparticles are extremely sensitive to their size and shape. Single particle spectroscopy techniques have therefore become the standard for understanding how the energy of the localized surface plasmon of individual nanoparticles scales with small changes in the morphology. Chemical methods have progressed to the point where researchers can facilely grow and assemble plasmonic nanostructures potentially useful for improving technologies in computing, communication, biomedical imaging and sensing, and therapeutics. Very small and very large nanostructures each present a unique set of challenges, and a separate strategy for each kind of sample is necessary for fully revealing the relationships among size, shape, orientation, and spacing between nanoparticles. This Perspective discusses how different single particle imaging and spectroscopy techniques together with electron microscopy can be applied to reveal the relationships between the plasmonic response and the morphology of individual nanoparticles as well as their assemblies. In particular, we show examples from our own studies that examined large nanostructures and disordered assemblies.