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

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.

Quinine-Fabricated Surface-Enhanced Raman Spectroscopy Chiral Sensing Platform Enables Simultaneous Enantioselective Discrimination and Identification of Aliphatic Amino Acids

“…To investigate the SERS enhancement capabilities of the HPMS and NPoM platforms, we determined the analytical enhancement factor (AEF) by using the ring C–H in-plane vibrational mode of malachite green (MG) at 1173 cm –1 . Because the UV–vis absorption peak of malachite green is distributed in the range of 300–670 nm and there is no absorption peak around 785 nm, it will not be in resonance with the laser (785 nm) utilized for the SERS measurements . Thus, MG is an appropriate Raman label to evaluate the AEF of the HPMS and NPoM platforms.…”

“…27 Because the UV−vis absorption peak of malachite green is distributed in the range of 300−670 nm and there is no absorption peak around 785 nm, it will not be in resonance with the laser (785 nm) utilized for the SERS measurements. 28 Thus, MG is an appropriate Raman label to evaluate the AEF of the HPMS and NPoM platforms. The detailed peak assignment is listed in Table S1.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XII

“…Their spectroelectrochemical data showed that SERS intensities from silver nanoparticles can be optimized with appropriately applied potentials. Their work also 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 . Filho, Cunha, and Rivelino studied the SERS properties of the Lewis acid‐base (LA‐LB) complexes of p‐hydroxybenzoic and p‐mercaptobenzoic acids with CO 2 in the presence of silver.…”

“…Their work also 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. [25] Filho, Cunha, and Rivelino studied the SERS properties of the Lewis acid-base (LA-LB) complexes of p-hydroxybenzoic and p-mercaptobenzoic acids with CO 2 in the presence of silver. Their work demonstrated that the lowest singlet π-π* excitation of both LA-LB complexes is significantly red-shifted, which gives evidence for such a complexation with CO 2 .…”

Quantitative analysis model based on surface‐enhanced Raman spectroscopy of malachite green adsorbed on gold nanoparticles film substrates

“…9 The enhancement mechanism is mainly related to the large enhancement of electromagnetic field due to the surface plasmon resonance (SPR) of metal nanostructures or nanoparticles. 10 A typical SERS system considers the adsorption of molecules on the nanoparticle state of coinage metals, such as copper, silver, and gold. 11,12 Au nanoparticles (AuNPs) are often used as SERS substrates because of the SPR enhancement effect and special stability.…”