SERS from two-tier sphere segment void substrates.

Sphere segment void, or inverse opal, films prepared from a variety of coinage metals have shown promise as reliable and reproducible substrates for surface enhanced Raman spectroscopy (SERS). Sphere segment void substrates are prepared from colloidal templates consisting of one or more layers of polystyrene spheres. In this paper, we investigate the reflection spectra and SERS for a gold film consisting of two-tiers of spherical cavities, and show that the best SERS enhancements are obtained from substrates consisting of just a single layer of sphere segment voids.

Engineering SERS via absorption control in novel hybrid Ni/Au nanovoids.

Nanoscale voids (or 'anti-nanoparticles') embedded in gold films possess plasmon modes with a strong field component at the cavity entrance, radically different to nanoparticle plasmon modes. By creating Ni/Au hybrid rim nanostructures we show how selective coupling to void plasmons provides strong electric field enhancements leading to large surface-enhanced Raman scattering (SERS) signals from molecules adsorbed on the nanovoid film. Since the rim plasmon modes are relatively independent of the supporting void material these results pave the way for hybrid nanovoid structures which combine plasmonic and catalytic properties of the constituent materials in a controllable and reproducible way.