Figure 1: Concept of plasmon-hybridization directed characterization of surface plasmon perpendicular fields.
From: Mapping plasmonic near-field profiles and interferences by surface-enhanced Raman scattering
(a) Spatial distribution of near-fields associated with a typical surface plasmon standing-wave produced by a radially polarized cylindrical beam. (b) Illustration of a nanosphere-film junction coupling to the perpendicular (A) and in-plane (B) electric fields of the standing-wave along the dashed line in (a), resulting in vertical and lateral gap modes, respectively. (c) Calculated averaged Raman enhancement (RE) within the nanosphere-film junction generated by perpendicular (REz) and in-plane (RExy) electric fields of SPPs, exhibiting mode splitting. The blue line illustrates their enhancement ratio. (d) Schematic diagram of the proposed surface plasmon detection system based on plasmonic gap mode-assisted SERS imaging. (e) SERS spectra of 4-MBA molecules collected from a single nanosphere-film junction, with and without SPP excitation. Inset shows a simultaneously-obtained Raman image of a single nanosphere-film junction. (f) Back Fourier plane image of the reflected radially polarized laser beam. The dark ring confirms SPP excitation at the silver-air interface over all azimuthal directions.
