Ultrafast Acoustics

Researchers

Rémi Busselez
Gwenaëlle Vaudel
Vincent Juvé
Guillaume Brotons
Nicolas Delorme
Pascal Ruello
Coll. H. Piombini, P. Belleville CEA Le Ripault, V. Gusev, S. Raetz, N. Chigrev LAUM Le Mans Univ (Lmac Project). K. Nelson, C. Klieber (MIT, USA)

Vibrational properties of liquids and interfacial liquids

At Solid-Liquid interface, a drop of liquid film thickness towards nanoscale induces deep modifications of the liquid properties such as heat or particle transport, fluid rheology and lubrication. Among the properties impacted by the fluid size reduction and liquid-solid interface, the importance of the modifications in vibrational properties are actually scrutinized and debated. Despite this interest in interfacial liquids, experimental measures are not easily accessible at exceptions of Surface Force Apparatus and Atomic Force Microscopy techniques. We recently develop a home-built Time Dependant Brillouin Scattering permitting to reach the GHz dynamics range for liquids of thickness comprises between few microns to tenth of nanometers permitting to access to viscoelastic properties from the bulk liquids to thin films and may shed a new light on the comprehension of interfacial fluid properties.

TDBS measurements are also supported by molecular dynamics simulations which permits to bridge a gap between the length and time scales of both techniques and may relate modifications of macroscopic values such as viscoelastic properties to microscopic aspects.

TDBS spectra of glycerol at different temperaturesVelocity of longitudinal and transverse sound as a function of frequency obtained with molecular dynamics simulation of glycerol at different temperatures

Projects

ANR PlusDil

Probing elasticity at the nanoscale

The ability to generate and to detect with femtosecond lasers coherent acoustic phonons with very high frequency (10-100s GHz) offers an unique possibility to directly measure the propagation speed of these acoustic phonons in nanostructures and then to investigate the elasticity [1]. Within this context, we have applied our method to probe the elasticity of different systems. First of all, we have studied assemblies of silica nanoparticles (10nm). These are the central element in advanced coating of many lenses in the French project Laser MégaJoule of CEA-DAM. The realization of coating with NPs assemblies permits to remove the coating quite often after each LaserMegaJoule Impact and to renew then the lenses. However, no advanced investigations of the mechanical properties of these coating were achieved up to now. This was our task. In this study, we have been able then to reveal the nature of the contact between nanoparticles (Van der Waals or Hydrogen, Covalent) directly by evaluating how fast the coherent acoustic phonon propagate within a thin film made of this nanoparticle (see figure below). The transformation of such bond (called hardening process) was realized by chemists of CEA. We have been then able to extract the characteristic elastic modulus of films as thin as 70nm (but the technique can be applied to thinner system) [2]. This research has been selected by CEA DAM as one of the 25 more important results in 2017 of research at CEA DAM.

We have also recently applied this method to detect a phase transition in thin films of the multiferroic compound BiFeO3. In particular, we are able to distinguish the transition from the rhombhedral to tetragonal phase by analyzing the values of the sound velocity measured in sub-micrometric films [3].

Left: principal of a pump-probe method on a thin film made of an assembly of nanoparticles. The pump laser can induced mechanical resonances of the film that in turn induce some periodic modulation in time on the optical reflectivity. The latter one is measured with the probe beam Typicall mechanical oscillations are shown on the right where the change of frequency of the two first eigenmode clearly indicate the modification of the nanoscontact strength.

Related papers

Vapor Phase Ammonia Curing to Improve the Mechanical Properties of Antireflection Optical Coatings Designed for Power Laser Optics
J Avice, G Brotons, P Ruello, G Vaudel, A Guediche, H Piombini
Gels 9 (2), 140 (2023)

Advances in applications of time-domain Brillouin scattering for nanoscale imaging, VE Gusev, P Ruello, Applied Physics Reviews 5 (3), 031101 (2018)

Controlling the Nanocontact Nature and the Mechanical Properties of a Silica Nanoparticle Assembly, J Avice, C Boscher, G Vaudel, G Brotons, V Juvé, M Edely, C Méthivier, Vitalyi E Gusev, Philippe Belleville, Herve Piombini, Pascal Ruello The Journal of Physical Chemistry C 121 (42), 23769-23776 (2017)

Evaluation of the structural phase transition in multiferroic (Bi1-x Prx)(Fe0.95 Mn0.05)O3 thin films by a multi-technique approach including picosecond laser ultrasonics, Samuel Raetz, Alexey Lomonosov, Sergey Avanesyan, Nikolay Chigarev, Elton de Lima Savi, Alain Bulou, Nicolas Delorme, Zheng Wen, Qiao Jin, Maju Kuriakose, Anthony Rousseau, Gwenaëlle Vaudel, Pascal Ruello, Di Wu, Vitalyi Gusev, in revision in Applied Sciences