Probing plasmonic nanostructures by photons and electrons.

We discuss recent developments for studying plasmonic metal nanostructures. Exploiting photons and electrons opens up new capabilities to probe the complete plasmon spectrum including bright and dark modes and related local optical fields at subnanometer spatial resolution. This comprehensive characterization of plasmonic properties of metal nanostructures provides new basic insight into the fundamental physics of "surface enhanced" spectroscopy in hottest hot spots and enables us to optimize plasmon supported processes and devices.