SHG OF METALLIC NANOPARTICLES : FROM ASSEMBLIES TO SINGLE PARTICLE

The Second Harmonic Generation response from metallic nanoparticles assemblies (from large ensembles down to the single nanoparticle level) homogeneously dispersed in transparent matrices (liquids, gels) is studied by the technique of Hyper Rayleigh Scattering (HRS) resolved in polarization.

We have observed the multipolar contributions to the SHG response from these systems (from the dipolar up to the octupolar contribution) and determined the origin of the response (surface vs volume origins) for different size, shape or composition of the nanoparticles.

SHG MICROSCOPY OF METALLIC NANO-STRUCTURES

The optical Second Harmonic Generation (SHG) response from gold metallic nanostructures (e.g. nanocylinders or nanodisks) arranged in arrays of different geometries has been determined as a function of the input fundamental polarization angle. The resolved polarization technique allows us to lead to the origin of the nonlinear response.

SUPRAMOLECULAR CHIRALITY FROM ACHIRAL MOLECULES

The compression of monomolecular achiral organic molecules films at the air/water interface induces the formation of supramolecular chiral aggregates. The chiral properties of these films can be monitored using polarization resolved SHG. Magnetic dipole contributions have been shown to play a major role in the appearance of this chirality.

ACTIVE LIQUID – LIQUID INTERFACES

SHG can be used to investigate fundamental processes at liquid/liquid interfaces, ubiquitous interfaces in Nature. Using SHG, we can understand the structure and the dynamics of these interfaces. We have recently focused our attention to the process of assisted ion extraction at liquid/liquid interface, a process well known in nuclear effluents technology. For example, severe SHG intensity fluctuations have been observed during the ion extraction process.

BIO-MOLECULES AND BIO-MATERIALS FOR NONLINEAR OPTICS

Bio-imaging requires an in-depth understanding of the optical properties of biomolecules. We use Second Harmonic Generation to investigate biomolecules, like amino acids, peptides or proteins and biomaterials. Beyond the fundamental studies, we also examine the potential applications in the field of optics of biomolecules and biomaterials.