Dependence of Raman intensity on the surface coverage of silver nanocubes in SERS active monolayers

Control over surface coverage while fabricating efficient silver nanocube (AgNC) based SERS substrates is crucial to develop an enhanced electromagnetic field. These substrates with tunable surface coverages made it possible to demonstrate the dependence of the SERS enhancement on the surface coverage and to quantify the enhancement factors (EFs) in the SERS enhancement obtained in various surface coverages of AgNC monolayers. It was found that the EFs apparently increased with the increase of nanocube surface coverage. These results indicate that electromagnetic filed (EM) enhancement is the main factor for SERS activity. In addition to the effects of surface coverage of AgNCs on the SERS enhancement, the effects of surface plasmon resonance (SPR) on SERS enhancement reveal an interesting dependence of SERS intensity on the close degree between surface plasmon resonance (SPR) and laser wavelength. (C) 2014 Elsevier B.V. All rights reserved.