Séminaire

Vendredi 10 Juin 2022 à 11h00.

Séminaire TeamDoc/Alumni

''Pour cette première édition de la nouvelle programmation de séminaire TeamDoc/Alumni, nous aurons le plaisir d'entendre Antoine Bard, doctorant dans l'équipe MNP, et de recevoir Agathe Depraz, anciennement stagiaire de l'équipe DYNAMO et actuellement doctorante à Vrije Universiteit Amsterdam.

Première partie: Antoine BARD
Title: Hybridization of two organic materials with polaritonic metasurfaces
Abstract: The strong light matter coupling occurring when the light matter interaction overcome the damping, has found recently applications beyond the domain of optics, in chemistry or transport. These advances make crucial the development of various structures in strong coupling. In this talk we describe a new way to hybridize two materials and transfer energy through a surface plasmon over micrometric distances. Two patterned interlocked dyes arrays, one donor and one acceptor, are deposited on a silver surface by successive micro contact printing, leading to a pattern of 5 microns’ period. The dispersion relation of the structure is measured with reflectometry experiments and evidence the hybridization with the plasmon, and the formation of states mixing both excitons and the plasmon with similar weights. The mixing in these polaritonic metasurfaces enables an energy transfer mechanism in strong coupling, which is observed with luminescence experiments. As the donor and acceptor are spatially separated by a distance larger than the diffraction limit, the excitation transfer is directly measured and evaluated by comparison with dyes arrays without silver. The transfer from one material to the other in strong coupling could find applications in the excitation of organic devices with an efficient transfer and an easy access to the in-plane separated structures. Multimaterial polaritonic metasurfaces can also be extended to the vibrational strong coupling where the control of the energy states could find applications in strong coupling chemistry.
Antoine Bard is a PhD student since October 2019 in the Materials and Nanostructures Group of the Institute of Light and Matter of Lyon (France). The group develops research devoted to strong light-matter coupling in hybrid metal/semiconductor structures. Antoine Bard trained in physics and chemistry before specializing in condensed matter and optics during his master's degree. During his first year of PhD, he worked on multi-stacked J-aggregated dyes to characterize energy transfer before working on structured metasurfaces for the same purpose. He has also worked on core-shell nanoparticles for applications in catalysis chemistry. He is involved in the doctoral association and the institute council.

Deuxième partie: Agathe Depraz
Title: Using Ion Mobility Coupled to Mass Spectrometry to Unravel the Peptide Aggregation Mechanisms Involved in Neurodegenerative Diseases
abstract: Neurodegenerative diseases, such as Alzheimer’s, Amyotrophic Lateral Sclerosis or Parkinson’s diseases, are directly correlated with the aging process. On a molecular level, this is translated by the development of protein and peptide aggregates. However, the mechanism of aggregation, and especially the transition from soluble oligomers to insoluble fibrils, remains unclear. This is particularly important as neurodegenerative toxicity originates from the conformational intermediates that are formed along the aggregation pathway. The challenge here is to obtain structural information of the elusive intermediate conformers from their complex and heterogeneous environment. Therefore, in our MS-LaserLab team, we are developing a methodology that could reveal the identity, the structure and the temporal evolution of these key intermediates. The idea is to use a novel single experiment hyphenating droplets-based microfluidics electrospray ionisation, mass spectrometry, ion mobility spectrometry and InfraRed spectroscopy. Here, we are highlighting the heart of this experiment by showing how ion mobility mass spectrometry (IM-MS), and more specifically Trapped ion mobility spectrometry (TIMS) can be used to follow the early stages of oligomer formation. Typically, to monitor aggregation, we track the linear increase of both mass and charge of the monomeric ion, over several time points. Where the mass over charge ratio isn’t sufficient to identify the different oligomers, the mobility dimension offers the possibility to observe their presence and determine their CCS value. To do so, complex instrumental parameters need to be optimised to allow both the study of intact aggregates and ensure their transmission towards the detector. Understanding better these processes and being able to characterize them would eventually allow us to explore new strategies to prevent and/or stop the aggregation.
Agathe Depraz Depland is a former master student at UCBL and intern at ILM, team DYNAMO. She is currently a PhD candidate ''