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Dr. Thais Couasnon

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Dr. Thais Couasnon
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0000-0002-7952-7619
Haus A 71, Raum 224 (Büro)
Telegrafenberg
14473 Potsdam

Funktion und Aufgaben:

Postdoctoral fellow in the group Interface Geochemistry (section 3.5)

Wissenschaftliche Interessen:

Thaïs Couasnon did her PhD at the Institut de Physique du Globe de Paris, on the biomineralization of manganese on the surface of bacterial biofilms. During her PhD, she collaborated with the Laboratoire Matériaux et Phénomènes Quantiques (MPQ) of the Université Paris Cité to image the biomineralization process in a liquid at the submicrometer scale and at high temporal resolution using liquid phase transmission electron microscopy. She is currently a postdoctoral fellow at the German Research Center for Geosciences (GFZ) to develop this relatively new technique to study the formation and transformation of minerals in situ, in order to better understand the mechanisms governing the mobility and bioavailability of elements in natural and industrial settings.

Karriere:

November 2019 - present: Postdoctoral researcher in Interface Geochemistry (section 3.5)

volunteering: EAG communication committee

Werdegang / Ausbildung:

  • 2015 - 2019 - Ph.D. Earth and Environmental Science: "Role of reactive oxygen species and substances exopolymeric bacteria in the process of biomineralization of manganese"
    Institut de Physique du Globe de Paris (IPGP), Paris, France
    Advisors: Alexandre Gélabert and Bénédicte Ménez

  • 2013 - 2015 - M.S. Chemistry
    Ecole Normale Supérieure Ulm, Paris, France
  • 2009 - 2012 - B.S. Chemistry and Biology,
    Université Joseph Fourier, Grenoble, France

Projekte:

NEWS:

July 2023: Our latest paper on Liquid-Phase TEM was released in Advanced Sciences. As part of our understanding of the influence of the incident electron beam irradiation on water chemistry, the paper provide experimental proofs of the anticipated radiolytic chemistry during a liquid-phase TEM experiment.Liquid phase transmission electron microscopy (LP-TEM) allows in situ observations of the dynamic behavior of materials in liquids with both high spatial and temporal resolution. One of the main drawbacks of this technique comes from the interaction of the incident electrons with the water molecules constituting the solvent of the liquid cell. This result in a significant change in chemistry of the aqueous solution, inevitably impacting the actual phenomena observed.

We used goethite minerals as a marker system to probe the water chemistry during LP-TEM. According to morphological features, the results show that at lower electron flux density goethite crystals are subjected to acidic dissolution. On the contrary, at higher electron flux density, dissolution is enhanced and morphological evolution does not correspond anymore to a unique acidic dissolution process. Together with kinetic simulations of the steady state concentrations of generated reactive species in the medium, the results provide a unique insight into the redox and acidity interplay during radiation chemistry in LP-TEM, but also successfully provide an experimental assessment of the simulation of the radiolytic products formed under electron irradiation in the liquid cell.This work could not be done without the contribution of our collaborators from Friedrich-Alexander-Universität Erlangen-Nürnberg, Forschungszentrum Jülich GmbH and Fraunhofer Institute for Integrated Systems and Device Technology IISB.
May 2023: Happy to share our latest contribution to the Journal of Physical Chemistry Letters: "Tailoring the Acidity of Liquid Media with Ionizing Radiation: Rethinking the Acid–Base Correlation beyond pH". This work sheds light on the concept of acidity during the interaction between ionizing radiation (electrons and photons) and liquid phases. A glimpse of the story in the JPCL cover : https://pubs.acs.org/toc/jpclcd/14/20

more info: https://lnkd.in/esXxye4i

Auszeichnungen:

•2021: Successful synchrotron proposal EXAFS at P65, DESY synchrotron, Hamburg, Allemagne
•2017: International mobility grant Université Sorbone Paris Cité, 3000euros
•2017: Successful synchrotron proposal STXM at HERMES, SOLEIL synchrotron, France
•2015: Ph.D grant from ministerial scholarship

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