A spectroelectrochemical investigation of nanoparticle and molecular resonances in surface enhanced Raman scattering from crystal violet and malachite green

Authors:
Publisher website
Google Scholar
Abstract
The interaction between nanoparticle plasmonic states and molecular electronic states is central to the large enhancements observed in surface‐enhanced Raman scattering (SERS). In this work, we use a model previously used in a fully quantum mechanical description of SERS to explain the enhancement of nontotally symmetric modes for crystal violet (CV) and malachite green (MG) adsorbed on silver nanoparticles. Our explanation is consistent with recent observations of the absorption spectra of dyes on silver nanoparticles that show the absence of charge‐transfer in these systems. Resonance with plasmon and molecular states explains the enhancement of nontotally symmetric modes, with enhancement dominated by the plasmon states. Spectroelectrochemical SERS studies using the same silver nanoparticles that are used to generate SERS in solution show increased SERS intensity for CV with positive potential up to +0.4 V (vs Ag/AgCl), consistent with a red‐shifted plasmon resonance, and decreasing intensity with more positive potentials, consistent with oxidation of the silver nanoparticles. Both crystal violet and malachite green show similar spectroelectrochemical behaviour with 514.5 nm excitation. Our spectroelectrochemical data show that SERS intensities from silver nanoparticles can be optimised with appropriately applied potentials. This work has highlighted the need for more detailed studies of the spectroelectrochemistry of dyes adsorbed on silver nanoparticles to more fully understand how SERS intensities respond to applied potentials. Copyright © 2016 John Wiley & Sons, Ltd.

This publication has 36 references indexed in Scilit: