Surface roughness induced electronic Raman scattering

Otto, A.; Timper, Jan; Billmann, J.; Kovacs, G. J.; Pockrand, I.

doi:10.1016/0039-6028(80)90237-x

Cited by 66 publications

(43 citation statements)

References 9 publications

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“…In particular, the background follows Bose statistics and that comforts unambiguously its interpretation as inelastic scattering by electron-hole pair excitations [14,17,19,20,22,43]. In particular, Portales et al have exactly drawn the same conclusions by analyzing Raman scattering by Ag-NCs embedded in SiO 2 but elaborated within a very different technique [17].…”

Section: A Stokes and Anti-stokes Electronic Raman Scatteringmentioning

confidence: 55%

“…One verifies that our model not only well accounts for the main characteristic of the "background" shape, but also for the linear dependence of its maximum frequency versus the confinement parameter D −1 , following Eqs. (15) and (14). The confinement similarly affects both acoustic and electronic waves, following a D −1 behavior, but their dynamical scales are very different, in the femtosecond or picosecond regime, respectively.…”

Section: Determination Of G S Parametermentioning

confidence: 99%

“…Among them, the presence of a continuous signal, the so-called "background," on which the molecular signatures are superimposed in all SERS spectra, is still subject to peculiar attention. Since the pioneering works on this subject [13][14][15][16], the background generated by rough silver surfaces or nude silver nanoparticles has been undoubtedly ascribed to Raman scattering by electron-hole excitations. It has been observed that the shape of this signal is related to the size of the metal particles [16], and a linear dependence of the frequency of its maximum intensity versus the inverse of the size of silver nanocrystals (Ag-NCs) has been demonstrated [17].…”

Section: Introductionmentioning

confidence: 99%

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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: A Stokes and Anti-stokes Electronic Raman Scatteringmentioning

confidence: 55%

Section: Determination Of G S Parametermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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“…The presence of a structureless background which stretches from the excitation line to beyond -5000 cm-I on the Stokes side was noted very early [2, 31. This continuum background has also been observed in the absence of any adsorbate [4]. On the other hand, no adsorbate lines have ever been reported without the presence of continuum background.…”

Section: Introductionmentioning

confidence: 78%

The Continuous Background of SERS from Ag Colloids in Alkali Halide Crystals

Abel

Fischer

1991

Physica Status Solidi (b)

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The continuum background of the SERS spectrum from thermally or photochemically prepared Ag colloids in alkali halide crystals is studied from − 5000 to + 1400 cm−1 and for counting rates covering three decades. The Stokes side consists of three contributions extending to about − 1500, − 3800, and beyond − 5000 cm−1 for 488 nm exciting light. As long as there is no evidence for hot luminescence it may be interpreted as SERS caused by charge‐transfer from the Fermi sea of the silver to mobility states and band‐tail states of the host and to localized surface states of the colloid. The anti‐Stokes intensity of the continuum background is found to follow a Boltzmann law between room temperature and 80 K.

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“…The enhancement of the signals is mainly caused by two effects: electromagnetic (EM) enhancement and a chemical contribution (Osawa and Ikeda, 1991). Compared with EM enhancement, the charge transfer-based chemical contribution provides a much smaller enhancement and the actual mechanism is still in dispute (Otto, 2005;Otto et al, 1980;Tognalli et al, 2011). The electromagnetic enhancement utilizes the LSPR of nanostructures to form incident electric field which could drive the conduction electrons.…”

Section: Sers Experiments With Ultrasmall Gold Nanoparticlesmentioning

confidence: 99%