Multiscale plasmonic nanoparticles and the inverse problem

This Perspective describes how multiscale plasmonic structures with two or more length scales (fine, medium, coarse) provide an experimental route for addressing the inverse problem. Specific near-field and far-field optical properties can be targeted and compiled into a plasmon resonance library by taking advantage of length scales spanning three orders of magnitude, from 1 to greater than 1000 nm, in a single particle. Examples of multiscale 1D, 2D, and 3D gold structures created by nanofabrication tools and templates are discussed, and unexpected optical properties compared to those from their smaller counterparts are emphasized. One application of multiscale particle dimers for surface-enhanced Raman spectroscopy is also described.