Fig. 3: Enhancement of Raman signal as a function of distance from the surface.
a Simulated E4 enhancement (log scale) in the xz-plane for a 22 nm thick gold membrane with a 10 nm by 68 nm slot on SiO2. b The experimental (blue triangle) and simulated (grey circles) enhancement for the graphene 2D Raman mode are shown as a function of SiO2 spacer thickness between the porous Au membrane and graphene. The black line is an exponential fit to the simulated values. The light red dashed area marks the volume within which 90% of the total Raman enhancement occurs. The simulated enhancement is normalized to the value at z = −0.35 nm, which is equivalent to the thickness of single layer graphene.
