LAUSR

An ultra-sensitive SERS (surface-enhanced Raman scattering) substrate was fabricated orderly by depositing 360 nm Ag film on the surface of V-shaped AAO (anodized aluminum oxide), utilizing NaOH solution to remove the AAO template, the neat volcano-like Ag arrays substrate (N-V-Ag) was obtained, and then depositing 1.5, 6 and 10 nm Ag film on the surface of the N-V-Ag to obtain the AgNPs decorated volcano-like Ag arrays substrates (AgNPs-V-Ag-1.5, AgNPs-V-Ag-6 and AgNPs-V-Ag-10, respectively). Experimental results indicated that the cavity resonance mode (super-radiant bright modes) and the rim mode as well as “NP mode” (subradiant dark mode) have strong interferences, which results in a significant change in the distribution of the hot spots in the cavity compared with the N-V-Ag. The analytical enhancement factor (AEF) of AgNPs-V-Ag could reach up to 1.5 × 1011, improved by 5 orders of magnitude compared with the N-V-Ag. This novel substrate could obtain extremely low limits of detection (LOD) of 10−13 mol/L (-13 M) for Rhodamine 6G (R6G).