Raman spectra of benzoic acid enhanced by the silver nanoparticles of various sizes

Abstract

Using sodium borohydride as the reducing agent and polyvinyl pyrrolidone (PVP, MW = 10 000) as the stabilizer, we obtained silver nanoparticles of various diameters (8-78 nm) from silver nitrate aqueous solutions in the concentration range from 0.001 to 0.1 M. The surface-enhanced Raman scattering (SERS) from benzoic acid's ring-breathing mode at 1003 cm −1 was detected from its dilute solutions (∼10 −2 M) doped with these silver nanoparticles under 488-nm laser excitation. The observed size dependences of SERS intensities fit quite well with those calculated by Schatz's theoretical model for spherical silver nanoparticles. The only exception occurred with the smallest particles (8 nm), possibly due to the failure of Maxwell's electromagnetic theory used in this model.

SERS enhancement of gold nanospheres of defined size

“…[24 -27] In contrast, in SERS experiments using nanoparticles in solutions, particles can be probed without inter-particle coupling effects. [28] Still, also in a solution of nanoparticles, the addition of analyte can cause some aggregation, which leads to an enormous increase in the enhancement, as has already been shown previously in both experiments [29 -31] and theory. [32,33] Aggregation is also indicated by an extended plasmon band to longer wavelengths that provides optimum enhancement of excitation and scattering fields in the near-infrared region.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part V

“…Using sodium borohydride as the reducing agent and polyvinyl pyrrolidone as the stabilizer, Zheng et al . obtained silver NPs (AgNPs) of various diameters (8–78 nm) from silver nitrate aqueous solutions . SERS from the ring‐breathing mode of benzoic acid was detected doped with these AgNPs using 488‐nm laser excitation to find a correlation between degree of enhancement and AgNP size.…”

Electrodeposition of silver nanoparticles in the presence of different complexing agents by time‐resolved Raman spectroelectrochemistry

“…In the specific case of silver nanoparticles (AgNPs), there is a substantial literature on their catalytic, electrochemical, optical, and antimicrobial properties that make them particularly interesting in catalysis, electronic, and sensors fields . Although the synthesis of AgNPs has been studied in the presence of several complexing ligands, Raman spectroelectrochemistry offers a unique factor in the in situ study of this process due to surface‐enhanced Raman scattering (SERS) effect is closely related to the properties of the substrate generated, an aspect that can determine the usefulness of AgNPs as a SERS substrate . Taking into account that Raman spectroscopy is one of the most powerful techniques in the detection and characterization of a huge variety of systems, the combination of this spectroscopic technique with an electrochemical response provides information of different nature in a unique experiment.…”