Fig. 13From: A Novel SERS Substrate Platform: Spatially Stacking Plasmonic Hotspots FilmsRaman spectra of a ascorbic acid molecules with the concentration changing from 10−2 to 10−9 M and b 4-MBA with the concentration changing form 10−2 to 10−10 M in the dual-layer porous Au films. The sputtering time of each layer of porous Au films is 47 s. Laser power: 0.24 mWBack to article page