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Plasmon-resonant spectroscopies in noble metal nanostructures: vibrationnal and electronic continua

In noble metal nanostructures, interactions between light, electronic and vibrational excitations are widely modified comparing with what occurs in bulk materials. Their sizes are significantly smaller than the light wavelength, skin depth, electron mean free path, acoustic wavelength…. Resulting confinement and damping effects on dynamics of either collective or individual, either atomic or electronic vibrations, have been analyzed through plasmon-resonant Raman scattering under specific experimental conditions on a panel of composite multilayer samples. On one hand, we show that the so-called “background" in SERS is an intrinsic phenomenon due to inelastic scattering by electronic excitations. Its enhancement, spectral lineshape and size-dependence is well accounted for by applying a dirty-metal model, early developed to describe electronic scattering in superconductors. On the other hand, we experimentally show, for the first time, that the vibrational density of states is modified when the surface/volume atom ratio is reduced (the 3D-2D transition), thus leading to thermodynamical anomalies. These fundamental studies are of prime importance for understanding SERS phenomenon, but also for various applications, like photo-catalaysis and thermo-plasmonics.

Contact: robert.carles[at]cemes.fr

 

Plasmon-resonant Raman spectroscopy in metallic nanoparticles: Surface-enhanced scattering by electronic excitation. R Carles, M Bayle, P Benzo, G Benassayag, C Bonafos, G Cacciato, V. Privitera . Phys. Rev. B 92 (17), 174302, 2015

 

Enhancing carrier generation in TiO2 by a synergistic effect between plasmon resonance in Ag nanoparticles and optical interference. G. Cacciato · M. Bayle · A. Pugliara · C. Bonafos · M. Zimbone · V. Privitera · MG. Grimaldi · R. Carles. Nanoscale, 7, 13468-13476 (2015)

 

Experimental investigation of the vibrational density of states and electronic excitations in metallic nanocrystals, M Bayle, P Benzo, N Combe, C Gatel, C Bonafos, G Benassayag, R. Carles. Phys. Rev. B 89 (19), 195402, 2014

 

Vibrational and electronic excitations in gold nanocrystals. M Bayle, N Combe, NM Sangeetha, G Viau, R Carles. Nanoscale 6 (15), 9157-9165, 2014.

 

Vibrational density of states and thermodynamics at the nanoscale: the 3D-2D transition in gold nanostructures, R. Carles, P. Benzo, B. Pécassou and C. Bonafos. Scientific Reports 6, 39164 (2016)

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