Nanoacoustics:
vibrational properties of metallic and multimaterial nanoparticles

Nanoacoustique :
propriétés virbationnelles de nanoparticules métalliques et hybrides

 

In a nanosystem, vibrational modes are also modified due to the presence of the surfaces. For metal nanoparticles constituted by few hundred atoms or more, the lowest energy confined acoustic modes can be described as the vibration eigenmodes of an elastic homogeneous object. Their properties depend on sound velocity and density of the material, and on the boundary conditions imposed by the shape and surrounding matrix. For instance, the fundamental vibrational mode of a nano-sphere corresponds to a volume modification (dilation and contraction), and is associated to a phonon with a wavelength equal to the sphere diameter.

We have demonstrated optical excitation and real time detection of these acoustic modes, using a femtosecond pump-probe techniqueThe pump pulse coherently excites the nanoparticle mechanical vibrations, which are optically detected by the time-delayed probe pulse through induced modifications of their optical absorption. Our investigations on metal nanospheres (Au, Ag, Pt, …) and elongated nanoparticles (nanorods, nanobyramids), and on bi-material nano-objects (Au@Pd, Ag@SiO2, Pt@Au, alloyed and segregated AuAg,…), coupled with analytical and finite-element computations, led to advances in the elucidation of the physical mechanisms at the origin of excitation and detection of vibrational modes and of the energy transfer from acoustic modes to the environment.

Beyond the fundamental interest, the properties of these vibrational modes, frequency and damping, are correlated to the shape, size and environment of the nano-objects. They can thus be employed in order to analyze nanomaterials and, particularly, their interface properties.

In a nanosystem, vibrational modes are also modified due to the presence of the surfaces. For metal nanoparticles constituted by few hundred atoms or more, the lowest energy confined acoustic modes can be described as the vibration eigenmodes of an elastic homogeneous object. Their properties depend on sound velocity and density of the material, and on the boundary conditions imposed by the shape and surrounding matrix. For instance, the fundamental vibrational mode of a nano-sphere corresponds to a volume modification (dilation and contraction), and is associated to a phonon with a wavelength equal to the sphere diameter.

We have demonstrated optical excitation and real time detection of these acoustic modes, using a femtosecond pump-probe techniqueThe pump pulse coherently excites the nanoparticle mechanical vibrations, which are optically detected by the time-delayed probe pulse through induced modifications of their optical absorption. Our investigations on metal nanospheres (Au, Ag, Pt, …) and elongated nanoparticles (nanorods, nanobyramids), and on bi-material nano-objects (Au@Pd, Ag@SiO2, Pt@Au, alloyed and segregated AuAg,…), coupled with analytical and finite-element computations, led to advances in the elucidation of the physical mechanisms at the origin of excitation and detection of vibrational modes and of the energy transfer from acoustic modes to the environment.

Beyond the fundamental interest, the properties of these vibrational modes, frequency and damping, are correlated to the shape, size and environment of the nano-objects. They can thus be employed in order to analyze nanomaterials and, particularly, their interface properties.

 

 

Selection of publications on nanoacoustics

Selection of publications on nanoacoustics

 

T. Stoll, P. Maioli, A. Crut, J. Burgin, P. Langot, M. Pellarin, A. Sánchez-Iglesias, B. Rodríguez-González, L. M. Liz-Marzán, N. Del Fatti, and F. Vallée

"Ultrafast Acoustic Vibrations of Bimetallic Nanoparticles"

Journal of Physical Chemistry C 119, 1591-1599 (2015)

 

A. Crut, P. Maioli, N. Del Fatti, and F. Vallée

"Acoustic vibrations of metal nano-objects: Time-domain investigations"

Physics Reports 549, 1-43 (2015) (review)

 

A. Crut, P. Maioli, N. Del Fatti, and F. Vallée

"Time-domain investigation of the acoustic vibrations of metal nanoparticles: Size and encapsulation effects"

Ultrasonics 56, 98-108 (2014) (review)

 

M.F. Cardinal, D. Mongin, A. Crut, P. Maioli, B. Rodríguez-González, J. Pérez-Juste, L.M. Liz-Marzán, N. Del Fatti, and F. Vallée

"Acoustic Vibrations in Bimetallic Au@Pd Core-Shell Nanorods"

Journal of Physical Chemistry Letters 3, 613-619 (2012)

 

D. Mongin, V. Juvé, P. Maioli, A. Crut, N. Del Fatti, F. Vallée, A. Sanchez-Iglesias, I. Pastoriza-Santos, and L.M. Liz-Marzan

"Acoustic Vibrations of Metal-Dielectric Core–Shell Nanoparticles"

Nano Letters 11, 3016-3021 (2011)

 

A. Crut, V. Juvé, D. Mongin, P. Maioli, N. Del Fatti, and F. Vallée

"Vibrations of spherical core-shell nanoparticles"

Physical Review B 83, 205430 (2011)

 

V. Juvé, A. Crut, P. Maioli, M. Pellarin, M. Broyer, N. Del Fatti, and F. Vallée

"Probing Elasticity at the Nanoscale: Terahertz Acoustic Vibration of Small Metal Nanoparticles"

Nano Letters 10, 1853 (2010)

 

 

Full list of publications of the FemtoNanoOptics group

Liste complète des publications de l'équipe FemtoNanoOptics

 

Retour à la page d'acceuil de l'équipe FemtoNanoOptics

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