Hot-Spot Engineering in 3D Multi-Branched Nanostructures: Ultrasensitive Substrates for Surface-Enhanced Raman Spectroscopy

The detection of probe molecules at ultralow concentrations, even at the single-molecule level, can be addressed with the breakthrough concept of plasmonic hot-spot engineering. In view of that, the fabrication of nanostructures endowed with sub-10 nm gaps and extremely large near-field enhancement has gained increasing attention, becoming a key-condition for improved sensitivity. The present work demonstrates a new perspective in ultrasensitive detection by engineering every individual plasmonic nanostructure with a giant electric field confinement and superior hot-spot densities, thus eliminating the need for extremely narrow interparticle separations.