Large-scale nanoplasmonic modeling: Improving convergence

Plasmonic devices have attracted huge attention from the scientific community over the last decade owing to their ability to render highly localized electromagnetic fields in the visible and near-infrared, such that numerous cutting-edge nanotechnology applications are arising that hinder on this unique property. Amongst them, surface-enhanced Raman scattering (SERS) is a spectroscopic technique that can yield high sensitivity (down to single molecule detection) and support multiplexing. Its working mechanism boils down to the fact that optical fields impinging on a metallic particle can bring its electrons on the conduction band to a collective and coherent self-sustained oscillation or localized surface plasmon resonance (LSPR). These resonant modes are capable of generating highly enhanced fields within sub-diffraction volumes near the vicinity of the particle, thereby enhancing, in turn, the Raman scattering from the adsorbed molecules in the analyte solution (that is, there is a twofold magnification which translates into an intensity enhancement at the optical detector that scales with the forth power of the incident electric field). A judicious combination of these nanoparticles, either in mono- and multi-layer colloidal arrangements or periodic supercrystals, leads to collective effects that can boost this response.