Surface-Enhanced Sensitivity From Tunable Plasmonic Nanostructures Arrays

The realization of periodic plasmonic nanostructures featuring macroscopic scale and easily controllable size and lattice spacing, is a challenging achievement for low-cost nanofabrication tools, which has not been completely explored so far. In this work, periodic array of different metal nanostructures have been easily prepared on large-area by exploiting a modified nano-sphere lithography (NSL) fabrication technique. A valuable ability is to couple the versatility offered by NSL with post-processing tools for a properly engineering of plasmonic nanoparticles. Obtaining dynamic tunability of metal nanostructures will allow the monitoring of electromagnetic near field distribution upon interaction with light of a desired wavelength. A rational design of such singular or collective optical properties can be used to focus and optimize the investigated functional features. Here, Au nano-prisms (NPs) and Au nanohole (NHs) arrays, tailored on the nanoscale, are investigated as innovative sensing platforms and as substrates for surface enhanced Raman scattering (SERS). Their localized "sensing volume", defined as the penetration depth within which changes of the refractive index can be detected, demonstrated their excellent performances towards single-molecule detection.