J. Vongsvivut, E. Robertson, D. McNaughton
Oct 1, 2010
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Influential Citations
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Quality indicators
Journal
Journal of Raman Spectroscopy
Abstract
Surface-enhanced Raman scattering (SERS) spectra of fonofos, an organophosphorous pesticide (OPP), were recorded using citrate-reducedsilver(Ag)andgold(Au)colloidalnanoparticlesintheformofdriedfilms.Inthisstudy,significantenhancements wereachievedwithfonofosconcentrationsdownto ∼10 ppmwiththeAgcolloids,demonstratingapotentialforthetechnique in the analysis of fonofos residues. Successful formation of the SERS-active metal aggregates was indicated by the presence of a plasmon band at longer wavelengths in the UV‐visible spectrum. Transmission electron microscopy (TEM) images revealed distinctively different morphologies of the aggregates formed by the two metals, while the observed SERS spectral features of fonofos were also found to be different for molecules adsorbed on Ag and Au colloidal surfaces. This evidence suggests metal-induced changes in adsorption behavior of the fonofos analyte, leading to the different binding structures onto the different metal surfaces. Comparisons between the most prominent SERS-enhanced bands and the precise mode descriptions predictedthroughdensityfunctionaltheory(DFT)simulationsattheB3LYP/6-311+G(d,p)levelallowedanin-depthorientation analysisoftheadsorbedspeciesonmetalsurfaces.Nevertheless,theringvibrationswerefoundtopossessamajorcontribution in the observed SERS enhancementsfor both metal nanoparticles. Copyright c � 2010 John Wiley & Sons, Ltd. Supporting information may be found in the online version of this article.