Understanding the Surface-Enhanced Raman Spectroscopy “Background”

Mahajan, Sumeet; Cole, Robin M.; Speed, Jonathon; Pelfrey, Suzanne H.; Russell, Andrea E.; Bartlett, Philip N.; Barnett, Stephen M.; Baumberg, Jeremy J.

doi:10.1021/jp907197b

Cited by 130 publications

(145 citation statements)

References 31 publications

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“…Analyzing more precisely the spectral shape of the background is thus still of high interest, either experimentally or theoretically, because this signal does appear as an intrinsic phenomenon that cannot be separated from the SERS effect [18,19,28,29]. The link between SERS and background signal is evidenced by the same resonant behavior versus excitation wavelength [20,29], the same dependence on tip-sample distance in TERS experiments [5], and same time dependence for the blinking phenomenon [27].…”

Section: Introductionmentioning

confidence: 99%

Plasmon-resonant Raman spectroscopy in metallic nanoparticles: Surface-enhanced scattering by electronic excitations

et al. 2015

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Since the discovery of surface-enhanced Raman scattering (SERS) 40 years ago, the origin of the "background" that is systematically observed in SERS spectra has remained questionable. To deeply analyze this phenomenon, plasmon-resonant Raman scattering was recorded under specific experimental conditions on a panel of composite multilayer samples containing noble metal (Ag and Au) nanoparticles. Stokes, anti-Stokes, and wide, including very low, frequency ranges have been explored. The effects of temperature, size (in the nm range), embedding medium (SiO 2 , Si 3 N 4 , or TiO 2 ) or ligands have been successively analyzed. Both lattice (Lamb modes and bulk phonons) and electron (plasmon mode and electron-hole excitations) dynamics have been investigated. This work confirms that in Ag-based nanoplasmonics composite layers, only Raman scattering by single-particle electronic excitations accounts for the background. This latter appears as an intrinsic phenomenon independently of the presence of molecules on the metallic surface. Its spectral shape is well described by revisiting a model developed in the 1990s for analyzing electron scattering in dirty metals, and used later in superconductors. The g s factor, that determines the effective mean-free path of free carriers, is evaluated, g expt s = 0.33 ± 0.04, in good agreement with a recent evaluation based on time-dependent local density approximation g theor s = 0.32. Confinement and interface roughness effects at the nanometer range thus appear crucial to understand and control SERS enhancement and more generally plasmon-enhanced processes on metallic surfaces.

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Section: Introductionmentioning

confidence: 99%

Plasmon-resonant Raman spectroscopy in metallic nanoparticles: Surface-enhanced scattering by electronic excitations

et al. 2015

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“…Spectral acquisitions are taken using an integration time of 1 s and the laser power on the sample is 30μW, with dark counts of the EMCCD subtracted. The lack of significant background, which originates from the electronic continuum in the metal 26 , is a consequence of the high field localization within the molecular gap layer. …”

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confidence: 99%

Tracking Nanoelectrochemistry Using Individual Plasmonic Nanocavities

et al. 2017

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We study in real time the optical response of individual plasmonic nanoparticles on a mirror, utilized as electrodes in an electrochemical cell when a voltage is applied. In this geometry, Au nanoparticles are separated from a bulk Au film by an ultrathin molecular spacer. The nanoscale plasmonic hotspot underneath the nanoparticles locally reveals the modified charge on the Au surface and changes in the polarizability of the molecular spacer. Dark-field and Raman spectroscopy performed on the same nanoparticle show our ability to exploit isolated plasmonic junctions to track the dynamics of nanoelectrochemistry. Enhancements in Raman emission and blue-shifts at a negative potential show the ability to shift electrons within the gap molecules.

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“…Nevertheless, though the subtraction should cancel the background associated with the fluorescence of Au and the wing of the Rayleigh scattering, an additional background can exist. Indeed, it has been reported recently [22] that non-fluorescent molecules (in our case dye molecules) can give some background. This background cannot be cancelled by the proposed subtraction procedure.…”

Section: Resultsmentioning

confidence: 90%

Probing plasmonic system by the simultaneous measurement of Raman and fluorescence signals of dye molecules

Tronc¹,

Lashkaryov²

2011

Semicond. Phys. Quantum Electron. Optoelectron.

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Abstract. The simultaneous measurement of Raman and fluorescence signals was proposed to find out the molecule-metal distance. The ratio between Raman and fluorescence intensities was used to estimate molecule-metal distance in nanometer scale. A low-value intensity of the fluorescence of the dye molecules was found using the photobleaching effect. Made was a comparison of experimental results with a theoretical model, which showed well agreement.

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Understanding the Surface-Enhanced Raman Spectroscopy “Background”

Cited by 130 publications

References 31 publications

Plasmon-resonant Raman spectroscopy in metallic nanoparticles: Surface-enhanced scattering by electronic excitations

Plasmon-resonant Raman spectroscopy in metallic nanoparticles: Surface-enhanced scattering by electronic excitations

Tracking Nanoelectrochemistry Using Individual Plasmonic Nanocavities

Probing plasmonic system by the simultaneous measurement of Raman and fluorescence signals of dye molecules

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