title: Nanogap ring antennae as plasmonically coupled SERRS substrates.
abstract: The fabrication, optical characterization, and application of a new generation of ultrasmall multiple-split nanoring antennae is reported. Using electron-beam lithography, splits of ≈6 nm are engineered into silver nanophotonic ring structures to create concentrated areas of localized field coupling, which can be exploited for enhanced plasmonic applications. The plasmonic properties of three devices, containing 3, 4, and 5 splits, which have been spectrally tuned to 532 nm, are compared. Using finite-element analysis, the distinct plasmonic characteristics of each structure are explored and a description is given of how variations in the surface charge distribution affect intersegmental coupling at different polarization angles. The impact these changes have on the sensory functionality of each device was determined by a competitive DNA-hybridization assay measured using surface-enhanced resonance Raman spectroscopy. The geometry of these novel, circular, multiple-split rings leads to unique plasmon hybridization between the numerous segments of a single structure. This phenomenon is demonstrated to be applicable to extreme Raman sensitivity and may also find use in metamaterial applications.
authors.affiliation: School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow, UK.
authors.forename: Alasdair W
authors.initials: AW
authors.lastname: Clark
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Cooper
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D036103:Nanotechnology / Q000379:methods*; D013059:Spectrum Analysis, Raman
chemical_list: D004247:DNA