Research data supporting "Accessing Plasmonic Hotspots using Nanoparticle-on-Foil Constructs"

Research data supporting "Accessing Plasmonic Hotspots using Nanoparticle-on-Foil Constructs" Figure 1c: Coupling of IMI + MIM = MIMI modes in a nanoparticle-on-foil cavity. Dispersion of MIMI modes for different t with d=1nm compared to IMI and MIM modes; surface plasmon on thick Au and free-space photon. Figure 1d: Effective propagation index of MIMI modes for increasing t at λ=633nm. Figure 1e: E_z near-fields from full-wave simulations of NPoF with plane wave excitation for t=15nm and t=5nm film thickness at the nanocavity resonance. The field null in the metal-film just above the substrate and the leakage of nanocavity fields into the substrate are clearly seen. Fig.1f: E_z near-fields from full-wave simulations of NPoF geometry with dipole source exciting the NPoF gap centre for t=10nm at λ=633nm, and IMI modes travelling away from the AuNP. Figure 2a,b. Far-field scattering from NPoFs, dark-field scattering spectra obtained from different individual NPoF cavities for (a) t=20nm and (b) t=10nm along with the average spectra. Figure 2c: Simulated scattering spectra for NPoF cavities vs decreasing foil thickness t from 30nm to 5nm. Figure 2d: Simulated far-field radiated intensity for NPoF cavity. Figure 3a: Average SERS enhancements in NPoFs Average SERS spectra for 3 different film thicknesses. Figure 3b: Histogram of extracted SERS 1585 cm-1 peak and background intensities. Figure 3c: Variation in the ratio of SERS background to SERS peak intensities. Figure 4a: Wavelength-dependent near-field enhancements in NPoFs extracted from the centre of the BPT-gap layer and fields 2nm below the Au-foil for different film thickness. Figure 4b: Near-field enhancement map for t=10nm at the nanocavity resonance. Figure 4c: Extracted near-field profile along z-axis (at x=0) for different film thickness.We acknowledge support from the European Research Council (ERC) under the Horizon 2020 Research and Innovation Programme THOR (829067) and POSEIDON (861950) and PICOFORCE (883703). We acknowledge funding from the EPSRC (Cambridge NanoDTC EP/L015978/1, EP/L027151/1, EP/S022953/1, EP/P029426/1, and EP/R020965/1). R.C. acknowledges support from Trinity College, University of Cambridge