Super-resolution imaging of interactions between molecules and plasmonic nanostructures.

Super-resolution far-field imaging has recently emerged as a novel strategy for imaging interactions between plasmonic nanostructures and single molecules with spatial resolution <5 nm. In these experiments, the emission centroid of a diffraction-limited spot is modeled as a two-dimensional Gaussian, allowing the position of an emitter to be determined with nanoscale precision. In this perspective, we describe the principles of super-resolution far-field imaging and then highlight its application to several different problems in plasmonics, including surface-enhanced fluorescence of ligands bound to nanoparticle surfaces, nanoparticle-mediated catalysis, and mapping electromagnetic hot spots. In all cases, the complex coupling between molecular emission and plasmon modes of the underlying nanostructure must be considered. While this complicates the interpretation of super-resolution images of plasmonic systems, the coupling also opens new doors for understanding the fundamental interactions between molecules and plasmonic nanostructures.