Figure 2

Topography (a,d,g,j) and s-SNOM near-field images (b,e,h,k) of the fabricated samples: (a–f) correspond to the Au10 sample, and (g–l) to the Au20 sample. The polarisation direction is indicated in the near-field images. Panels (c,f,i,l) represent the topography (blue) and near-field signal (red) extracted along the white lines in the maps next to them showing the electric field confinement in the gaps of the nanostructured films. Additional images of other areas are included in the SI. The white scale bar is 200 nm.