Particle-in-a-Frame Nanostructures with Interior Nanogaps.

Designing plasmonic hollow colloids with small interior nanogaps would allow structural properties to be exploited that are normally linked to an ensemble of particles but within a single nanoparticle. Now, a synthetic approach for constructing a new class of frame nanostructures is presented. Fine control over the galvanic replacement reaction of Ag nanoprisms with Au precursors gave unprecedented Au particle-in-a-frame nanostructures with well-defined sub-2 nm interior nanogaps. The prepared nanostructures exhibited superior performance in applications, such as plasmonic sensing and surface-enhanced Raman scattering, over their solid nanostructure and nanoframe counterparts. This highlights the benefit of their interior hot spots, which can highly promote and maximize the electric field confinement within a single nanostructure.