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

TL;DR

This paper introduces a straightforward optical method to detect and identify organic shells around silver nanoparticles by comparing experimental extinction spectra with theoretical Mie calculations, complemented by SERS for confirmation.

Contribution

The study presents a novel combined optical and spectroscopic approach to detect and identify organic shells on plasmonic nanoparticles, specifically applied to silver nanoparticles with ethylene glycol shells.

Findings

Successful detection of organic shells using optical extinction and Mie theory.

Identification of ethylene glycol as the organic shell via SERS.

Method applicable to other plasmonic nanoparticles with organic coatings.

Abstract

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.