Sensitive SERS measurement with a single nanoshell-plane junction under radially polarized focused excitation

Nanoshells are one of versatile plasmonic nanostructures in biomedical applications due to highly tunable optical properties and near-field enhancement. By exciting the nanoshell-plane junction with a radially polarized (RP) focused excitation, we have obtained further near-field boosting and consequent highly sensitive surface enhanced Raman scattering (SERS) of a monolayer of malachite green isothiocyanate molecules. This work expands the vertical antenna under RP excitation method for ultra sensitive and reproducible SERS measurement from nanospheres to nanoshells.