Surface-enhanced Raman spectroscopy as a monitor of iron(III) protoporphyrin reduction at a silver electrode in aqueous and acetonitrile solutions: vibronic resonance enhancement amplified by surface enhancement

Sánchez, Luis A.; Spiro, Thomas G.

doi:10.1021/j100251a009

Cited by 47 publications

(26 citation statements)

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“…Likewise, the SER spectrum of hematin on Ag sol resembles its RR spectrum (Figs 4A and 6A). This is consistent with previous reports [43,44] which showed that the band positions and intensity profile of the SER spectra of metalloporphyrins are quite similar to those observed in their RR spectra, demonstrating that the adsorption of metalloporphyrins on the Ag surface happens through electrostatic interaction rather than charge transfer complexation. In this case, the molecular electronic states are not appreciably altered by the adsorption on the surface, and the RR selection rules still determine the relative strength of the bands.…”

Section: Ters With Inactive Probessupporting

confidence: 93%

“…Therefore, the general character of the Raman scattering is established by the molecule itself, with the SERS substrate acting as an amplifier. [43] On the other hand, the TER and associated tip-surface-enhanced Raman spectra of hematin show considerable changes in the enhancement pattern and wavenumber values when compared to the RR spectrum (Figs 4A, D, and 6D). The appearance of new bands can be related to the activation and enhancement of IR active modes in Raman spectra due to the loss of the symmetry of the molecule as a result of its interaction with probe silver atoms and/or tip pressure effect.…”

Section: Ters With Inactive Probesmentioning

confidence: 94%

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Exploring the origin of tip‐enhanced Raman scattering; preparation of efficient TERS probes with high yield

Asghari-Khiavi

Wood

Hojati-Talemi

et al. 2011

J Raman Spectroscopy

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Tip-enhanced Raman scattering (TERS) spectroscopy is a promising technique for nanoscale chemical analysis. However, there are several challenges preventing widespread application of this technology, including reproducible fabrication of efficient TERS probes. These problems reflect a lack of clear understanding of the origins of, and the parameters influencing TERS. It is believed that the coating characteristics at the apex of the tip have a major effect on the near-field optical enhancement and thus the TERS activity of a metalized probe. Here we show that the aspect ratio of the tip can play a significant role in the efficiency of TERS probes. We argue that the electrostatic field arising from the lightning-rod effect has a substantial role in the observed TERS effect. This argument is supported by 'edge-enhanced Raman scattering' which is shown for a noble metal film. Furthermore, it is reported that an associated tip-surface-enhanced Raman scattering effect can be achieved by using a TERS-inactive metalized probe on a surface-enhanced Raman spectroscopy-inactive roughened surface. This observation can be explained by an interparticle enhancement of the electromagnetic field.

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Section: Ters With Inactive Probessupporting

confidence: 93%

Section: Ters With Inactive Probesmentioning

confidence: 94%

Exploring the origin of tip‐enhanced Raman scattering; preparation of efficient TERS probes with high yield

Asghari-Khiavi

Wood

Hojati-Talemi

et al. 2011

J Raman Spectroscopy

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“…However, one noticeable difference between SERR and RR spectra in this excitation region is that b 1g modes are much weaker than b 2g modes in the SERR spectra, but the opposite behavior was observed in RR spectra, 26 despite the fact that both b 1g and b 2g modes gain their (resonance) intensity via the JT effect. For example, 10 (1650), 11 (1505) and 13 (1185) all display higher intensities than 29 (1356) and 34 (1195) in Soret-excited RR spectra, 26,27,29 but the opposite pattern is observed here in SERRS. The redistribution of JT activity from the b 1g to b 2g mode in SERR spectra with Soret excitation is very likely associated with the orientation of NiP on the colloid surface, reflecting an interplay between SERS effect and resonance (vibronic) effect (see below).…”

Section: Enhancement Patterns In Serrsmentioning

confidence: 51%

Surface‐enhanced resonance Raman spectroscopy of water‐insoluble Ni(II) porphine adsorbed on aqueous silver sol: suppression of antisymmetric scattering, antiresonance effect and higher order scattering

Петров

Chen

et al. 2001

J Raman Spectroscopy

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With the intention of examining how adsorption on a SERS-active surface affects the electronic resonance enhancement in surface-enhanced resonance Raman scattering (SERRS) from Ni(II) porphine (NiP), we acquired high-quality SERR spectra from very low concentrations of NiP (∼10 −8 M) in aqueous Ag sol from 50 to 3500 cm −1 with excitations across both the Soret and Q absorption bands. Water-insoluble NiP was transferred to aqueous silver sol surface by using pyridine as carrying solvent, taking advantage of the fact that it both dissolves NiP and is partially miscible with water at the same time. It was found that SERS boosts the overall sensitivity of resonance Raman scattering by providing extra enhancement (the surface enhancement) to a 1g , b 1g and b 2g modes, but not to a 2g modes. As a consequence, a relative 'suppression' effect of antisymmetric scattering by a 2g modes was observed when excitation was tuned into the Q absorption band region in SERR spectra. With excitations in the valley between the Soret and Q absorption bands, an antiresonance effect was observed in the SERR spectra for the totally symmetric n 6 mode at 995 cm −1 which was attributed to the destructive interference between Franck-Condon and Herzberg-Teller mechanisms. Strong second-order and weak third-order Raman scattering were observed in the SERR spectra of NiP when excitation was tuned close to and across the Q 1 absorption band. A vibronic theory based on the extension of Albrecht's formalism was developed to account for the activation of high-order Raman scattering and for the antiresonance effect of the n 6 band. More than 100 Raman wavenumbers, including both fundamentals and overtones/combinations, both in-plane and out-of-plane modes, were observed for NiP in its SERRS spectra. The wavenumbers from the SERR spectra agree very well with those obtained from RR spectra from a homogeneous NiP solution and FTIR data from KBr (CsI) pellets, suggesting that adsorption of NiP on a SERS-active surface is physisorption in nature, and that such adsorption has a negligibly small effect to the vibrational wavenumbers. The observed Raman wavenumbers from SERR spectra are also in excellent agreement with those predicted from ab initio/DFT calculations for both in-plane and out-of-plane modes. Many out-of-plane modes and IR-active in-plane modes were observed in the SERR spectra of NiP, suggesting that the effective symmetry of the adsorbed NiP is lower than the ideal planar D 4h .

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“…Previous studies reveal that surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) on silver electrodes [10][11][12][13][14][15] and silver colloids [16][17][18][19] in aqueous solution produce intense, highly resolved spectra. Numerous chemical species have been investigated, such as: organic compounds [17,[20][21][22][23][24][25][26][27][28], acids and bases [18,29,30], dyes [31][32][33][34], porphyrin-related compounds and biomolecules [9,19,[35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

SERRS and visible extinction spectroscopy of copper chlorophyllin on silver colloids as a function of pH

House¹,

Schnitzer²

2008

Journal of Colloid and Interface Science

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Surface-enhanced Raman spectroscopy as a monitor of iron(III) protoporphyrin reduction at a silver electrode in aqueous and acetonitrile solutions: vibronic resonance enhancement amplified by surface enhancement

Cited by 47 publications

References 0 publications

Exploring the origin of tip‐enhanced Raman scattering; preparation of efficient TERS probes with high yield

Exploring the origin of tip‐enhanced Raman scattering; preparation of efficient TERS probes with high yield

Surface‐enhanced resonance Raman spectroscopy of water‐insoluble Ni(II) porphine adsorbed on aqueous silver sol: suppression of antisymmetric scattering, antiresonance effect and higher order scattering

SERRS and visible extinction spectroscopy of copper chlorophyllin on silver colloids as a function of pH

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