Raman scattering by electron-hole excitations in silver nanocrystals

Portalès, Hervé; Duval, E.; Saviot, Lucien; Fujii, Minoru; Sumitomo, M.; Hayashi, Shinji

doi:10.1103/physrevb.63.233402

Cited by 33 publications

(31 citation statements)

References 17 publications

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“…One can conclude from this analysis that the frequency maximum of the electronic inelastic scattering band only depends on geometry and displays a linear dependence on the inverse of the average diameter in spherical NCs. The same trend has been already observed by Portales et al [17].…”

Section: Size Effectsupporting

confidence: 79%

“…13 (full squares) as a function of the inverse of the mean diameter D −1 . On this figure are also reported (empty squares) values deduced from already published Raman spectra of Ag clusters embedded in SiO 2 [17]. 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.…”

Section: Determination Of G S Parametersupporting

confidence: 53%

“…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: 54%

“…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]. More recently, the background dependence on local morphology and surface roughness has been once more underlined [18], and a direct link between the line shape of the background and the mean diameter of the NCs assembly has been put forward using a phenomenological approach [19,20].…”

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: Size Effectsupporting

confidence: 79%

Section: Determination Of G S Parametersupporting

confidence: 53%

Section: A Stokes and Anti-stokes Electronic Raman Scatteringmentioning

confidence: 54%

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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“…An experiment of this kind was carried out in supported Ag clusters [29]. The analysis of the data suggested, however, that the E2 rather than the SM was populated through the E1 decay.…”

Section: Resonant Raman Scatteringmentioning

confidence: 99%

Orbital magnetism in axially deformed sodium clusters

Nesterenko

Kleinig

Reinhard

et al. 2003

The European Physical Journal D - Atomic, Molecular and Optical

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Low-energy orbital magnetic dipole excitations, known as scissors mode (SM), are studied in alkali metal clusters. Subsequent dynamic and static effects are explored. The treatment is based on a self-consistent microscopic approach using the jellium approximation for the ionic background and the Kohn-Sham mean field for the electrons. The microscopic origin of SM and its main features (structure of the mode in light and medium clusters, separation into low-and high-energy plasmons, coupling high-energy M1 scissors and E2 quadrupole plasmons, contributions of shape isomers, etc) are discussed. The scissors M1 strength acquires large values with increasing cluster size. The mode is responsible for the van Vleck paramagnetism of spin-saturated clusters. Quantum shell effects induce a fragile interplay between Langevin diamagnetism and van Vleck paramagnetism and lead to a remarkable dia-para anisotropy in magnetic susceptibility of particular light clusters. Finally, several routes for observing the SM experimentally are discussed.

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