Theoretical surface-enhanced Raman spectra study of substituted benzenes

Fleming, Guillermo Díaz; Golsio, Italo; Aracena, Andrés; Célis, Freddy; Vera, Leticia; Koch, Rainer; Campos‐Vallette, Marcelo

doi:10.1016/j.saa.2008.02.046

Cited by 36 publications

(7 citation statements)

References 35 publications

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“…This can be contrasted with the upshift observed for nitriles with a perpendicularly oriented CN group, i.e. interacting with the metal forming a σ bond with the lone pair of the N atom . In the case of thiacloprid, π back‐bonding would therefore be prevalent .…”

Section: Discussionmentioning

confidence: 89%

Surface‐enhanced Raman spectra of the neonicotinoid pesticide thiacloprid

Cañamares

Feis

2013

J Raman Spectroscopy

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Thiacloprid is a widely used pesticide belonging to the neonicotinoid class, which is characterized by a selective activity against insects and a reduced acute toxicity for humans. The importance of the environmental impact of neonicotinoids is being intensively researched, in order to evaluate the danger they pose for useful insects. Physical methods which allow the characterization of neonicotinoids in diluted aqueous solutions are therefore desirable. We present a study of Raman and surface‐enhanced Raman scattering (SERS) spectroscopy on thiacloprid in solid state, in acetone solution, and adsorbed onto silver and gold hydrosols at μM concentration. Density functional theory calculations allow the individualization of the most stable molecular structure, both in gas phase and in solution, and of the corresponding Raman spectra. The vibrational assignments lead to an interpretation of the differences between SERS and ordinary Raman spectra based on the possible interactions between the molecule and the metal surface, the main one involving the iminocyano group. Formation of a charge‐transfer complex is suggested by the dependence of the SERS spectra on the laser excitation wavelength. We evaluate the applicability of SERS spectroscopy to the chemical analysis of thiacloprid comparing SERS with current analytical methods. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Discussionmentioning

confidence: 89%

Surface‐enhanced Raman spectra of the neonicotinoid pesticide thiacloprid

Cañamares

Feis

2013

J Raman Spectroscopy

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“…In the second case, it depends sensitively on the details of the chemical bonding between the adsorbates and the substrates. Therefore, the wavenumbers of the enhanced bands will change more or less 46–48. Many studies have shown that both mechanisms contribute to the overall effect (multiplicatively).…”

Section: Discussionmentioning

confidence: 99%

Adsorption of aniline on silver mirror studied by surface‐enhanced Raman scattering spectroscopy and density functional theory calculations

Xie

et al. 2011

J Raman Spectroscopy

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The adsorption of aniline on a silver mirror was studied by surface-enhanced Raman scattering (SERS) spectroscopy and density functional theory (DFT) calculation methods. The normal Raman and SERS spectra of pure aniline liquid and its solutions were recorded by a micro-Raman spectrometer with excitation at 514.5 nm. Orientation of the aniline molecule adsorbed on the Ag mirror is discussed. The results indicate that pure aniline is adsorbed on the surface of the Ag mirror with a tilted orientation. The conformer with the nitrogen atom interacting with the metal surface would be dominant. DFT calculations further confirm the experimental results that charge transfer (CT) takes place from the highest occupied molecular orbital(HOMO) of aniline to the singly occupied molecular orbital (SOMO) of the silver surface. In this paper, the frontier molecular orbital theory has been successfully used to explore the interaction between the aniline molecule and the silver surface.

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“…It is well known that SERS is sensitive to the local intermolecular charge transfer interaction between the active site of the adsorbate and the effective metal surface [4]. As a sensitive tool, SERS can provide useful information on surface bonding sites and the molecular orientation on the metal surface [5][6][7]. The SERS characteristics depend mainly on the adsorption behavior, which is determined by the properties of metal clusters and molecular configuration [8][9][10].…”

Section: Introductionmentioning

confidence: 99%