Optical determination and identification of organic shells around nanoparticles: application to silver nanoparticles

Abstract : We present a simple method to prove the presence of an organic shell around silver nanoparticles (NPs). This method is based on the comparison between optical extinction measurements of isolated NPs and Mie calculations predicting the expected wavelength of the Localized Surface Plasmon Resonance of the NPs with and without the presence of an organic layer. This method was applied to silver NPs which seemed to be well protected from oxidation. Further experimental characterization via surface enhanced raman spectroscopy (SERS) measurements allowed to identify this protective shell as ethylene glycol. Combining LSPR and SERS measurements could thus give proof of both presence and identification for other plasmonic NPs surrounded by organic shells.