Mode-Selective Surface-Enhanced Raman Spectroscopy Using Nanofabricated Plasmonic Dipole Antennas

Mode-selective surface-enhanced Raman spectroscopy (SERS) is demonstrated using plasmonic dipole antennas fabricated with electron beam lithography. An similar to 10x change of the relative enhancement between two different Raman modes is observed when the resonance frequency of the plasmonic antennas is tuned over the Raman modes by varying the geometrical parameters of the antennas, i,e., changing their lengths or narrowing their feeding gaps. The comparison between the Rayleigh scattering spectra and the SERS spectra from the same individual plasmonic dipole antennas indicates that this mode-selective SERS phenomenon is a pure electromagnetic effect, providing a quantitative verification of the electromagnetic mechanism of SERS Oil a single nanoantenna level.