A tunable plasmon resonance in gold nanobelts.

Plasmonic nanowires with sub-100-nm rectangular cross sections were found to exhibit a strong transverse plasmon peak at visible wavelengths. By correlating atomic force microscopy measurements of individual nanobelts with their dark-field scattering spectra, it is seen that the transverse peak tunes with cross-sectional aspect ratio. Simulations revealed that the scattering plasmonic modes are transverse antisymmetric excitations across the nanobelt width. Unlike larger diameter silver nanowires, these nanobelts exhibit sharp, tunable plasmon resonances similar to those of nanoparticles.