Surface Enhanced Raman Spectroscopy of Individual Rhodamine 6G Molecules on Large Ag Nanocrystals

Michaels, Amy M.; Nirmal, M.; Brus, L. E.

doi:10.1021/ja992128q

Cited by 1,271 publications

(1,235 citation statements)

References 37 publications

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“…10). This result is roughly consistent with recent SERS data, which showed the presence of intense signals that appeared to be located between clusters of particles [20,21]. Emission spectra were collected from eight selected regions of varying brightness.…”

Section: Silver Fractal-like Structures On Glasssupporting

confidence: 90%

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Geddes

Parfenov

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et al. 2003

Journal of Fluorescence

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Substantial increases in fluorescence emission from fluorophore-protein-coated fractal-like silver structures have been observed. We review two methods for silver fractal structure preparation, which have been employed and studied. The first, a roughened silver electrode, typically yielded a 100-fold increase in fluorophore emission, and the second, silver fractal-like structures grown on glass between two silver electrodes, produced a ≈500-fold increase. In addition, significant increases in probe photostability were observed for probes coated on the silver fractal like structures. These results further serve to compliment our recent work on the effects of nobel metal particles with fluorophores, a relatively new phenomenon in fluorescence we have termed both "metal-enhanced fluorescence" [1] and "radiative decay engineering" [2,3]. These results are explained by the metallic surfaces modifying the radiative decay rate (Γ) of the fluorescent labels. We believe that this new silver-surface preparation, which results in ultrabright and photostable fluorophores, offers a new generic technology platform for increased fluorescence signal levels, with widespread potential applications to the analytical sciences, imaging, and medical diagnostics.

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Section: Silver Fractal-like Structures On Glasssupporting

confidence: 90%

“…Our findings show no enhancement in fluorescence emission after chloride dipping, which is consistent with MEF being a through-space phenomenon as compared to SERS, which conversely is thought to be a contact (or near contact) interaction with a metallic surface [20,21].…”

Section: Introductionsupporting

confidence: 85%

Untitled

Geddes

Parfenov

Roll

et al. 2003

Journal of Fluorescence

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“…The Rayleigh images were obtained in dark field configuration with grazing incidence white light -a technique borrowed from biological imaging. The Rayleigh image in figure 1 was striking; it showed plasmons at all different visible wavelengths (16). The Ag colloid showing the single molecule SERS thus has a huge range of sizes and shapes.…”

Section: Single Molecule Ramanmentioning

confidence: 95%

Noble Metal Nanocrystals: Plasmon Electron Transfer Photochemistry and Single-Molecule Raman Spectroscopy

2008

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IntroductionI remember the excitement when the SERS effect was discovered in the late 1970s (1,2). The Raman scattering cross section of pyridine adsorbed on a silver electrode was enhanced by 5 or 6 orders of magnitude! It was quickly understood that this represented plasmon local electromagnetic (EM) field enhancement on a rough surface, as explained below (3,4) . Actually two different EM fields are enhanced, the incoming laser field and the outgoing Stokes shifted field, making SERS especially dramatic. At that time I collaborated with Abe Nitzan on the related theoretical question: whether enhanced fields would create enhanced photochemistry(5,6). Certainly enhanced fields create an enhanced optical absorption cross section. But an excited molecule near a metal surface will undergo Forster energy transfer into the metal, and this process competes with photochemistry if the molecular excited state lifetime is long. As it turns out the energy transfer rate falls off faster than does field enhancement, and so photochemistry can be enhanced at some distance above the surface.After the initial excitement, experimental progress in SERS slowed, principally due to the extreme averaging that occurs in ensemble SERS measurements. On rough surfaces and in colloids, there is a huge distribution of molecular positions and orientations with respect to the surface, and also a wide range of different field enhancements due to different local metal topologies. I went on to work with semiconductor nanocrystals, where the issue was size-dependent development of band structure(7). Here a similar terrible ensemble averaging occurs over nanocrystal sizes, shapes and surface stiochometry. In the 1990s Betzig and Trautman created a significant advance in spectroscopic technique: observation of luminescence from spatially resolved single molecules and nanocrystals at 23 C on a surface, at first using fiber optic near field methods, and subsequently confocal far field methods (8,9,10, 11). Luminescence blinking, a signature of single molecule kinetics, was discovered in CdSe nanocrystals.In 1997 there were two unexpected reports of single molecule SERS, for dye molecules in Ag colloids(12, 13) . The combined enhancement of molecular resonance Raman and SERS was perhaps 14 orders of magnitude! The SERS single molecule Raman signal was actually at least an order of magnitude larger than a dye molecule or semiconductor nanocrystal luminescence signal in the absence of Ag. We began to explore this discovery, using the new confocal optical methods. There are two inter-related questions: where is the single molecule on the metal, and how is this molecule so strongly coupled to the excited metallic electrons. We found that the single molecule is in a junction between particles. Study of the coupling lead us to literature quantum mechanical models for photodynamics of chemisorbed molecules. We then experimentally discovered that adsorbed citrate surfactant anions, whose SERS signals are very weak compared to the dye molecule, are actually ...

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“…(2) The material can be detected in direct contact with the substrate. (3) The nanoparticles conform to different substrate profiles [175]. The yeast cells were measured through this technique and highquality molecular Raman spectroscopy can be obtained (see Figure 11).…”

Section: Sersmentioning

confidence: 99%

Exciton-plasmon coupling interactions: from principle to applications

et al. 2017

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Abstract:The interaction of exciton-plasmon coupling and the conversion of exciton-plasmon-photon have been widely investigated experimentally and theoretically. In this review, we introduce the exciton-plasmon interaction from basic principle to applications. There are two kinds of exciton-plasmon coupling, which demonstrate different optical properties. The strong exciton-plasmon coupling results in two new mixed states of light and matter separated energetically by a Rabi splitting that exhibits a characteristic anticrossing behavior of the exciton-LSP energy tuning. Compared to strong coupling, such as surface-enhanced Raman scattering, surface plasmon (SP)-enhanced absorption, enhanced fluorescence, or fluorescence quenching, there is no perturbation between wave functions; the interaction here is called the weak coupling. SP resonance (SPR) arises from the collective oscillation induced by the electromagnetic field of light and can be used for investigating the interaction between light and matter beyond the diffraction limit. The study on the interaction between SPR and exaction has drawn wide attention since its discovery not only due to its contribution in deepening and broadening the understanding of SPR but also its contribution to its application in light-emitting diodes, solar cells, low threshold laser, biomedical detection, quantum information processing, and so on.

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Surface Enhanced Raman Spectroscopy of Individual Rhodamine 6G Molecules on Large Ag Nanocrystals

Cited by 1,271 publications

References 37 publications

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Noble Metal Nanocrystals: Plasmon Electron Transfer Photochemistry and Single-Molecule Raman Spectroscopy

Exciton-plasmon coupling interactions: from principle to applications

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