Figure 3From: SERS substrates formed by gold nanorods deposited on colloidal silica filmsSEM images of mesoporous silica films differing in GNR deposition density. (a) Low. (b) Medium. (c) High. Note that the densely packed GNR layer (right-hand image) is similar to the fractal-like GNR assembly on a silicon wafer (Additional file 1: Figure S2b). The white bars are 100 nm long.Back to article page