Highly Raman-enhancing substrates based on silver nanoparticle arrays with tunable sub-10 nm gaps

Uniform and highly surface-enhanced Raman spectroscopic (SERS)-active substrates have been fabricated using Ag nanoparticle arrays with unprecedented small tunable gaps. The dependence of the enhancing capability of the substrate on the gap size provides quantitative evidence for the collective SERS effect and confirms predictions of interparticle-coupling-induced Raman enhancement.