Université de Strasbourg

Florian Banhart & Thomas LaGrange

Biography - Florian Banhart

Institute of Physics and Chemistry of Materials of Strasbourg (IPCMS), University of Strasbourg

Florian Banhart, USIAS Fellow 2017

Florian Banhart studied physics at the University of Stuttgart (Germany), where he received his PhD in 1988 under the mentorship of Alfred Seeger. From 1989 to 1999, he was a research scientist at the Max Planck Institute for Metals Research in Stuttgart and, from 1999 to 2003, at the University of Ulm, where he completed his habilitation in 2001. He was subsequently appointed professor of physical chemistry at the University of Mainz in 2003, where he chaired the Electron Mcroscopy Centre.

In 2007 he moved to take up his present post as professor of physcis at the Faculty of Physics and Engineering of the University of Strasbourg and is part of IPCMS. Florian Banhart was one of the 2011 laureates of the national excelle program EQUIPEX and has been senior member of the Institut universitaire de France since 2014.

His main research activities are in the fields of in-situ electron microscopy with focus on low-dimensional nanostructures of carbon and related materials. He studies atomic defects and diffusion, materials in non-equilibrium and under irradiation, high-pressure effects and phase transformations in nanomaterials, electrical transport through atomic chains, as well as the nucleation and growth of nanoparticles. His recent research activity is in the field of ultrafast electron microscopy.

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Biography - Thomas LaGrange

École Polytechnique Fédérale de Lausanne (EPFL)

Thomas LaGrange, USIAS Fellow 2017Thomas LaGrange is a materials scientist with an extensive background in electron microscopy techniques, TEM instrumentation development, and laser science and technology. He received a bachelor’s degree in mechanical engineering and master’s degree in materials science from Michigan State University and a Ph.D. in applied physics at the École polytechnique fédérale de Lausanne (EPFL). He joined Lawrence Livermore National Laboratory (LLNL) as a postdoc in 2005 and later as a staff scientist, where he developed the Dynamic Transmission Electron Microscope (DTEM) and the Movie Mode DTEM instrumentation for which he received two R&D100 Awards and a Microscopy Today Innovation Award. He left LLNL and joined Integrated Dynamic Electron Solutions, Inc. (IDES) in 2014 as the Chief Technology Officer. During his time at IDES, he constructed and installed the UTEM at IPCMS, University of Strasbourg and formed a collaboration with Florian Banhart to study ultrafast materials dynamics. Since 2015, he is a senior scientist at the Centre interdisciplinaire de microscopie électronique (CIME)and faculty lecturer at EPFL.

His main scientific interests are the study of non-equilibrium phase transition kinetics and the role of atomic defects on materials dynamics and how such defects influence a material’s macroscopic behaviour in applications. His recent research pursuits extend to the development of new ultrafast microscopy approaches to study materials dynamics and the use of aberration-corrected microscopy to characterize materials.

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Project - Ultrafast Transformations of Composite Nanoparticles

October 2017 - September 201

Phenomena at ultrashort timescales are attracting increasing interest. Lasers produce extremely intense light pulses with durations of femtoseconds whereas ultrashort X-ray pulses are generated in synchrotrons. These flashes of photons have already been applied to explore a world of phenomena in physics, chemistry and bio-medical science. However, all photon-based techniques suffer from limited spatial resolution. To overcome the spatial limitations, electron microscopy with ultrashort electron pulses has been developed in the past years. Such an ultrafast electron microscope has been installed, as part of the national EQUIPEX program, at the Institute of Physics and Chemistry of Materials of Strasbourg (IPCMS). This novel instrument will be used in the present project to study the behaviour of nanoparticles at short timescales and to combine high spatial with high temporal resolution.

Metallic nanoparticles play an important role in catalysis and are used in many industrial fields, e.g. in fuel cells and in the cleaning of exhaust gases. A common problem is the oxidation of metal particles that passivates them and prevents their catalytic activity. However, oxide particles can be reactivated by thermal treatment or reduction. Since the particles are only a few nanometers in size, structural and chemical transformations, even those that are diffusion controlled, are quite fast at these small length scales. In the present project, such transformations will be studied in a pump-probe approach. An irreversible transformation of the particles is induced by an infrared laser pump pulse. An intense electron pulse follows after a few nanoseconds, probing the evolution and the transformations in the sample through high spatial resolution imaging, electron diffraction, or electron energy-loss spectroscopy. These time-resolved, “snap-shot” observations are expected to give a detailed picture of the temporal evolution of the transforming particles. In such an approach, the reduction mechanism of oxide nanoparticles, transformations of core-shell particles, solid-liquid transitions, and compression effects will be studied. Of particular interest is the reduction mechanism in transition metal particles with native oxide shells which give crucial insight into mitigating passivation and mechanisms for reactivation of catalytic nanoparticles. The USIAS project will allow a detailed study of the behaviour of nanoparticles down to the nanometers and nanosecond scales

 

Investissements d'Avenir