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Vibrational and electronic excitations in gold nanocrystals
Nicolas Combe,Neralagatta M. Sangeetha,Guillaume Viau,Robert Carles
Nanoscale Pub Date : 05/19/2014 00:00:00 , DOI:10.1039/C4NR02185A
Abstract

An experimental analysis of all elementary excitations – phonons and electron–holes – in gold nanocrystals has been performed using plasmon resonance Raman scattering. Assemblies of monodisperse, single-crystalline gold nanoparticles, specific substrates and specific experimental configurations have been used. Three types of excitations are successively analyzed: collective quasi-acoustical vibrations of the particles (Lamb's modes), electron–hole excitations (creating the so-called “background” in surface-enhanced Raman scattering) and ensembles of atomic vibrations (“bulk” phonons). The experimental vibrational density of states extracted from the latter contribution is successfully compared with theoretical estimations performed using atomic simulations. The dominant role of surface atoms over the core ones on lattice dynamics is clearly demonstrated. Consequences on the thermodynamic properties of nanocrystals such as the decrease of the characteristic Debye temperature are also considered.

Graphical abstract: Vibrational and electronic excitations in gold nanocrystals
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