Research Activities
Plasmon and Vibration: opto-mechanical coupling
Due to its weak scattering
cross-section, measuring the inelastic light scattering linked to the
acoustic vibration modes of a single nanoparticle is a difficult task
. One way to compensate for this weak signal is to work with plasmonic
nanoparticles that give rise to the strongest signals. Understanding
how this optical property interacts with the vibration is essential
and this is one of our main tasks. Indeed, controlling such coupling
by tuning the geometry, environment, and assembly of these particles
could allow us to nano-engineer new types of materials with given
opto-mechanical properties.
Related publications:
2D Nanomaterials: Nanobalance effect
Nanostructures exhibit low frequency
vibrations ( lower than 50 cm-1 or 1.5 THz) that compare to 1D
standing waves of a string at the nanometer scale. Probing these modes
by Raman scattering was first evidenced 30 years ago at the University
Lyon 1 (E. Duval, A. Boukenter and B. Champagnon, PRL 1986). Since
then, low frequency Raman scattering has been used to characterize
various types of nanoparticles (quantum dots, dielectric NPs, metallic
NPs…), essentially from nanospherical morphologies (« Lamb modes »).
Our paper reports on the breathing vibration modes of atomically flat
nanoplatelets synthesized from colloidal chemistry. We show that the
presence of the organic ligands induces a significant reduction of the
resonance frequencies (downto -50%) through a mass lump effect. This
reduction conforms to continuum elasticity calculations. These results
make colloidal nanoplatelets promising nano-objects for nanobalance
applications.
Related publications:
BioBrillouin
The mechanical properties of
biological materials is of high interest. The sound velocity depends
on these mechanical properties and can be measured using Brillouin
light scattering. In collaboration with T. Dehoux (the biophysics team
at iLM), we are developing a new BioBrillouin setup to acquire this
signal in the case of cancer cell spheroids. This will enable us to
monitor the effect of drug treatments. My involvement consists in
developing the Brillouin spectroscopy technique to improve the
acquisition speed, with the aim of transferring this technology to
biological laboratories.
This work is supported by the Agence
Nationale de la Recherhe (ANR Porotume, grant no. ANR-17-CE11-0010-01)
and the Région Auvergne Rhône-Alpes (SCUSI no. 1700991901)
Related publication:
Experimental setups
Our laboratory is equipped with several spectrometers allowing us to
acquire low frequency scattering signal. We use either a
5-monochromator spectrometer with a focal length of 800 mm, or a
tandem Fabry-Perot from John Sandercock. The first spectrometer is
able to work with all visible wavelength (from 400 nm to 800 nm) and
allows to acquire signal down to 2 wavenumber (60 GHz) and up to 1500
wavenumber (45 THz) . The Brillouin spectrometer works with 405, 532,
and 650 nm depending on the mirrors used. It allows to acquire spectra
between 1 and 1500 GHz.
These spectrometers are coupled with confocal microscopes, to acquire
the signal from single nanoparticle.
We recently developped (PhD of Q. Martinet) a new setup to trap
single nanoparticle in liquid. The trapping is performed optically at
1064 nm. The next objective is to acquire the signal of a single gold
nanoparticle in liquid.
