The nanodisks were defined in the double resist layer on areas of 10×10 mm 2 with electron-beam lithography (Raith EBPG 5200) by exposing circles of 35 nm radius. Each circle was filled with 19 shots at a beam current of 50 nA and at a base frequency of 5.19 MHz. (iv) The 20 nm Cr discharge layer was removed by immersing the substrate for 60 s in Nickel/Chromium etchant (SunChem), followed by water rinsing and blow drying. (v) The exposed resist was developed for 60 s in MIBK 1:3 IPA solution, dried in N 2 -stream, and descummed in oxygen plasma for 5 s at 50 W RF-power, 250 mTorr chamber pressure, and 40 sccm gas flow in a BatchTop Reactive Ion Etcher (PlasmTherm). (vi) To form the nanostructures, Pd were deposited through the resist mask with electron-beam evaporation at a deposition rate of 1 Å/s in a PVD 225 system (Lesker), lifted off in acetone for 24 h, rinsed in IPA and blow dried in N 2stream. (vii) Finally, the wafer was diced (DAD3350, Disco) into individual chips of 10×10 mm 2 . For the control quasi-random array sample, the fabrication procedures (steps, materials, and tools used) followed exactly the protocol reported in ref. . The only difference was the polystyrene beads used, that is, 120 nm sulfate latex, Interfacial Dynamics Corporation, 0.2 wt.% in Milli-Q water (Millipore). The SEM images were collected from glass samples coated with 5 nm Cr layer (Zeiss Supra 60 VP with secondary electron detector, working distance 4 mm, and an electron beam acceleration voltage of 7-15 kV).