  We present a simple method to prove the presence of an organic shell around
silver nanoparticles. This method is based on the comparison between optical
extinction measurements of isolated nanoparticles and Mie calculations
predicting the expected wavelength of the Localized Surface Plasmon Resonance
of the nanoparticles with and without the presence of an organic layer. This
method was applied to silver nanoparticles 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 nanoparticles
surrounded by organic shells.
