Nanoscale surface-enhanced resonance Raman scattering spectroscopy of single molecules on isolated silver clusters

Meixner, Alfred J.; Vosgröne, T.; Sackrow, Marcus

doi:10.1016/s0022-2313(01)00248-4

Cited by 60 publications

(39 citation statements)

References 9 publications

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“…Ultimately, a single, very small structure and its adsorbate, such as a particle dimer and a single or a few adsorbed molecules, may produce Raman scattering which is sufficiently intense to be recorded. This concept may explain also the singlemolecule sensitivity of SERS reported by Nie and Emory, 14 Kneipp et al 15 and Meixner et al 18 In a sense, TERS is a variant of the idea of hot spots (although it has been developed along a somewhat different route). The main idea is to use the illuminated apex of an AFM or STM tip made of a suitable material as a near-field enhancer.…”

Section: Introductionmentioning

confidence: 91%

Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Pettinger

Ren

Picardi

et al. 2005

J Raman Spectroscopy

143

154

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Tip-enhanced Raman spectroscopy (TERS) was investigated with malachite green isothiocyanate adsorbed at an Au(111) surface. TERS is based on the excitation of localized surface plasmons in the tip apex, producing strongly enhanced electromagnetic fields. The key conditions for giant TERS are sideillumination of the tip, well-prepared single-crystalline surfaces and sharp, smooth gold tips. A TERS enhancement of about 6 × 10 6 has been observed for dye molecules adsorbed at the Au(111) substrate in a region of about 50 nm diameter beneath the tip. This corresponds to a 2500-fold increase in the light intensity at the Au(111)/air interface, which in addition causes fast but local bleaching of the dye. This bleaching behavior was analyzed in detail, giving direct insight into the strength and size of the enhanced field. In addition, the bleaching constant was higher for MGITC in an unperturbed environment than for MGITC in an environment that had been substantially bleached. The MGITC spectra were also different for these two cases. Copyright  2005 John Wiley & Sons, Ltd.KEYWORDS: apertureless scanning near-field optical microscopy; gold(111); tip-enhanced Raman spectroscopy; malachite green isothiocyanate; near-field enhancement INTRODUCTIONThe general use of Raman spectroscopy for surface studies is an old dream of surface scientists. However, with differential Raman cross-sections of the order of d /d ³ 10 31 -10 28 cm 2 sr 1 , surface studies were out of reach in general, although a (small) number of attempts were made to apply (normal) Raman scattering for the investigation of well-defined surfaces.Ł Correspondence to: Bruno Pettinger, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany. E-mail: pettinger@fhi-berlin.mpg. Recently, a new approach has been developed, denoted tip-enhanced Raman spectroscopy (TERS), in some cases also called 'apertureless scanning near-field optical microscopy (SNOM)'. 1 With the advent of TERS, the above-mentioned dream is now becoming a reality. 1 -12 TERS is a particular promising variant of SERS, the well-studied field of surface-enhanced Raman scattering spectroscopy. The latter requires roughened surfaces at which two cooperative enhancement mechanisms for Raman scattering are working. Roughened surfaces can support the excitation of localized surface plasmons leading to the so-called 'electromagnetic enhancement' and provide the peculiar adsorption sites at which the so-called 'chemical enhancement' is operative. In the literature, a large range of (total) enhancement factors are given, starting with the 10 6 -fold enhancement found for pyridine on roughened silver electrodes 13 up to the giant 10 12 -10 14 -fold enhancement reported more recently by Nie and Emory 14 and Kneipp et al. 15 for dyes at colloidal particles. In the latter case, the authors claim to have reached single-molecule detection sensitivity. However, in all these cases the general drawback of SERS investigations remains: the surface enhancement (in particular its ...

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Section: Introductionmentioning

confidence: 91%

Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Pettinger

Ren

Picardi

et al. 2005

J Raman Spectroscopy

143

154

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“…Complications may arise from the fact that in SERS the analytical signal commonly originates from only zeptomole to yoctomole quantities, located in highly localized fields. [116] The most obvious interference would be the Raman scattering signal arising from the surrounding medium and from contaminants that are also adsorbed at the enhancing surface. The characteristic "cathedral peaks" of graphitic or amorphous carbon (1360 and 1560 cm À1 ) have been widely reported in the SERS literature for a variety of substrates including that of enhancing metal tips.…”

Section: à2mentioning

confidence: 99%

Inherent Complexities of Trace Detection by Surface‐Enhanced Raman Scattering

Pieczonka¹,

Aroca²

2005

ChemPhysChem

104

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Surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) are powerful optical scattering techniques used in such frontier areas of research as ultrasensitive chemical analysis, the characterization of nanostructures, and the detection of single molecules. However, measuring and, most importantly, interpreting SERS/SERRS spectra can be incredibly challenging. This is the result of modifications to the measured spectra that are due to of a variety of instabilities and contributions. These interferences and modifications arise from the nature of the enhancement itself, as well as the conditions used to attain SERS spectra. The present report is an attempt to collect in one place the analytical interferences that are most commonly found during the collection of SERS/SERRS spectra.

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“…In general, SM SERS literature reports spectra that are clearly characteristic for the investigated molecule and thus allow identification of the adsorbed species, also at any time during serial acquisition. [6][7][8][9][10][11][12][13] Surface diffusion may indeed account for intensity fluctuations in SERS, where a rough surface provides a variety of different adsorption sites or hot spots for the molecule. 6,12 Changes in the band positions which have been observed in SM SERS studies include a narrowing or splitting of bands 11 and slight shifts of ± 2-5 cm −1 of band positions (which by far exceeds the resolution of the instrument of 25 cm −1 employed by Neacsu et al).…”

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confidence: 99%

Comment on “Scanning-probe Raman spectroscopy with single-molecule sensitivity”

Domke

Pettinger

2007

Phys. Rev. B

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We reinterpret the scanning-probe Raman spectra shown in the above paper [C.C. Neacsu et al., Phys. Rev. B 73, 193406 (2006)] and compare it to a variety of single-molecule surface-enhanced Raman (SER) studies. The observed blinking behaviour and spectral features must be attributed to carbon contaminations rather than to Malachite Green (MG) single molecules, because, under the given experimental conditions, the extremely high field enhancement of 5 x 10 9 will inevitably lead to a quick (photo)decomposition of the adsorbate.PACS numbers: 68.37. Uv, 33.20.Fb In a recent paper, 1 Neacsu et al. present an AFMtip-enhanced Raman (TER) study on Malachite Green (MG) at gold films. They analyze near-field (tip approx. 5 nm above sample surface) and far-field (tip several 100 nm above sample surface) spectra of a Au surface covered with MG at low adsorbate concentration in correlation with a DFT calculation as well as of the clean Au surface. In a time series of 100 AFM-TER spectra (1 s integration time per spectrum) for a submonolayer MG surface coverage, spectral diffusion is observed and interpreted as characteristic single-molecule (SM) behaviour due to "random surface diffusion of MG in and out of the near-field-confined surface area under the tip, facilitated by the thin most likely liquid water layer on the gold surface". A Raman enhancement of up to 5 x 10 9 is derived from comparison of tip-enhanced versus far-field response of the same surface monolayer.Figures 2b and 2c in Ref. 1 show a near-field (tip approached) and a far-field (no tip) spectrum of MG on Au, respectively. The far-field spectrum exhibits the typical Raman features of MG which can be ssigned according to Lueck et al. 2 ) and a DFT calculation (Fig. 2c in Ref. 1), but the near-field spectrum does not resemble neither the far-field nor the DFT spectrum.The authors state that "the pronounced spectral difference between the tip-enhanced and the far-field response resembles the observation frequently made in SERS" (surface-enhanced Raman spectroscopy) and claim that "this characteristical difference is the result of the strong optical field localization, and related to different selection rules for the tip-scattered response, akin to SERS". Different selection rules cannot be held responsible for the so remarkable differences between near-field and farfield spectra presented by Neacsu et al. Note in this context that SER as well as TER spectra usually strongly resemble the far-field spectra of the investigated species in the band positions, in a way that the unambiguous identification of the molecule is always possible. In fact, a comparison of the Raman bands found in literature for MG in water (far-field, Ref. 2) and MG on silver colloids (near-field, Ref.3) does not reveal any band displacements larger than ± 3 cm −1 , and also the relative band intensities are similar. Variations in band intensities may occur according to surface selection rules (changes in the polarizability perpendicularly to the surface, i.e. parallel to the incident...

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Nanoscale surface-enhanced resonance Raman scattering spectroscopy of single molecules on isolated silver clusters

Cited by 60 publications

References 9 publications

Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Tip‐enhanced Raman spectroscopy (TERS) of malachite green isothiocyanate at Au(111): bleaching behavior under the influence of high electromagnetic fields

Inherent Complexities of Trace Detection by Surface‐Enhanced Raman Scattering

Comment on “Scanning-probe Raman spectroscopy with single-molecule sensitivity”

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