We investigated the reduction of gold salt to gold nanoparticles by rutin. Without salt, there were no scattering bands at 450–500 cm–1 (C–C bending vibrations in the rings), but with routine, this scattering bands appeared. Take the ratio of intensities. It will be enhancement factor.
The enhancement factor (EF) is the key parameter for the assessment of SERS substrate performances. A great effort has been addressed to the definition of EF.8–10 Eqn (1) reports the most commonly employed definition: ISERS=NSERS EF 1⁄4 INR=NNR where the signal intensities measured in SERS and normal Raman (NR) are ISERS and INR.