Charge Transfer Processes in Surface-Enhanced Raman Scattering. Franck−Condon Active Vibrations of Pyridine

Arenas, Juan F.; López‐Tocón, Isabel; Otero, Juan C.; Marcos, J. I.

doi:10.1021/jp953712y

Cited by 130 publications

(138 citation statements)

References 41 publications

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“…5. Arenas et al [16] have reasoned that the experimental appearance of the modes at 1208 and 607 cm −1 on silver electrodes coincides with the appearance of CT. The displacements between the ground state of pyridine and its anion for these two vibrational modes are much larger than others, so relative intensities of SERRS spectra for these two normal modes are strongly enhanced.…”

Section: Chemical and Em Enhancement Mechanism Of Sers For The S-complexmentioning

confidence: 96%

“…[15,16,28] The idea is that by changing the electrode potential, the CT state can be tuned to be at resonance or away from it for certain incident excitation wavelengths. The relationship between the optical absorption energy in the absorption spectrum and the shift of electrode potential can be estimated with…”

Section: Chemical and Em Enhancement Mechanism Of Sers For The S-complexmentioning

confidence: 99%

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Direct visual evidence for the chemical mechanism of surface‐enhanced resonance Raman scattering via charge transfer

Sun

Chen

et al. 2008

J Raman Spectroscopy

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We describe the chemical and electromagnetic enhancements of surface-enhanced resonance Raman scattering (SERRS) for the pyridine molecule absorbed on silver clusters, in which different incident wavelength regions are dominated by different enhancement mechanisms. Through visualization we theoretically investigate the charge transfer (CT) between the molecule and the metal cluster, and the charge redistribution (CR) within the metal on the electronic intracluster collective oscillation excitation (EICOE). The CT between the metal and the molecule in the molecule-metal complex is considered as an evidence for chemical enhancement to SERRS. CR within the metal on EICOE is considered as an evidence for the electromagnetic enhancement by collective plasmons. For the incident wavelength from 300 to 1000 nm, the visualized method of charge difference density can classify the different wavelength regions for chemical and electromagnetic enhancement, which are consistent with the formal fragmented experimental studies.

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Section: Chemical and Em Enhancement Mechanism Of Sers For The S-complexmentioning

confidence: 96%

Section: Chemical and Em Enhancement Mechanism Of Sers For The S-complexmentioning

confidence: 99%

Direct visual evidence for the chemical mechanism of surface‐enhanced resonance Raman scattering via charge transfer

Sun

Chen

et al. 2008

J Raman Spectroscopy

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“…First, the HerzbergTeller correction is probably an important enhancement mechanism for non-totally symmetric modes of pyridine adsorbed on coinage metals, and has been used to interpret the SERS of pyrazine adsorbed on silver surfaces. [60] Secondly, the CT transition probability increases with the change in the configuration of the adsorbed pyridine from parallel to perpendicular orientation with respect to metal clusters of rhombic structures. As was pointed out in TDDFT calculations of PyÀAg 4 and PyÀAu 4 , the oscillator strengths increase with this orientation change.…”

Section: Vibrational Raman Spectra Of Pyàau M Ag Nmentioning

confidence: 98%

“…[48,60,61] For the v 1 , v 6a , v 8a , and v 9a modes, the CT mechanism always enhances their Raman signals for pyridine adsorbed on metal surfaces. This is due to large displacements of the minima at the CT state with respect to that at the ground state of these normal modes.…”

Section: Vibrational Raman Spectra Of Pyàau M Ag Nmentioning

confidence: 99%

Binding Interactions and Raman Spectral Properties of Pyridine Interacting with Bimetallic Silver–Gold Clusters

Ren

Zhang

2006

ChemPhysChem

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The binding interactions between pyridine and bimetallic silver-gold clusters are investigated using density functional theory (DFT). The binding energies of pyridine-bimetallic cluster complexes indicate that the bonding depends strongly on the binding site (Au or Ag atom) and bonding molecular orbitals in a given configuration. The donation of the lone-pair electrons of the nitrogen of pyridine to an appropriate unoccupied orbital of each metal cluster plays an important role. The low-lying excited states and charge-transfer states of four stable complexes of interest are calculated on the basis of a time-dependent DFT method. In nonresonance Raman scattering processes, the influence of binding interactions on the relative Raman intensity of totally symmetric pyridine vibrational modes is discussed. These calculated relative Raman intensities are compared with observed surface-enhanced Raman spectra of pyridine adsorbed on silver-gold alloy surfaces.

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“…CT effect is a short range enhancement and this effect is noticeable only for molecules adsorbing directly on the metallic nanoparticles. Molecules, such as pyridine, [4][5][6] pyrazine, 7,8 para-aminothiophenol, [9][10][11][12][13] crystal violet, 14 and tryptophan, 15 have been extensively studied to probe the CT effect in enhancement.…”

Section: Introductionmentioning

confidence: 99%

Distance‐dependent Enhancement in Raman Spectroscopy Probed by Conjugated Molecules with Different Molecular Lengths

Liou

Chen

Yang

2014

J Chinese Chemical Soc

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In this study, the distance-dependent enhancement effect in surface-enhanced Raman scattering (SERS) was explored with molecules bearing different lengths of conjugated double bonds. These conjugated molecules were synthesized utilizing the diazotization-coupling reaction allowing a thio group on one end and a nitro group on the other end. The thiol group allows the probed molecule to chemisorb on the surface of silver nanoparticles (AgNPs). The opposite end of each molecule contains a nitro group, which gives an intense SERS signal to show a fair and accurate comparison of the effect of chain length. The obtained SERS intensities were correlated with the chain lengths of these synthesized molecules, which ranged from 0.6 to 2.0 nm between the nitro and thiol groups. Based on these results, the electromagnetic field effect was mainly responsible for the signal enhancements in SERS measurements. Also, the obtained signals were exponentially decayed due to the distances of the surface of AgNPs. Based on the SERS intensities of the conjugated molecules, the contribution of CT effect to SERS for these examined molecules were limited.

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Charge Transfer Processes in Surface-Enhanced Raman Scattering. Franck−Condon Active Vibrations of Pyridine

Cited by 130 publications

References 41 publications

Direct visual evidence for the chemical mechanism of surface‐enhanced resonance Raman scattering via charge transfer

Direct visual evidence for the chemical mechanism of surface‐enhanced resonance Raman scattering via charge transfer

Binding Interactions and Raman Spectral Properties of Pyridine Interacting with Bimetallic Silver–Gold Clusters

Distance‐dependent Enhancement in Raman Spectroscopy Probed by Conjugated Molecules with Different Molecular Lengths

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