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Laboratory for Synchrotron Radiation and Femtochemistry (LSF)
Mission
We develop and apply x-ray-based tools to solve scientific and technological questions in chemical research and related fields. Our world-leading instruments allow us to extract electronic and structural information from complex systems and to follow chemical processes from the initial electronic excitation to reaction mechanisms under operando conditions. We collaborate with Swiss and international scientists to advance academic and industrial research.
Scientific Highlights
Spin cascade and doming in ferric hemes
In biology, structure and function are closely interwoven. A case in point is oxygen transport in the lungs, which relies on ferrous heme proteins adopting dome-like shapes.
First light in the SwissFEL Maloja endstation
The first endstation at the SwissFEL Athos soft X-ray branch is rapidly developing and on track for first experiments in 2021.
Unraveling the structural dynamics of Heme proteins at SwissFEL
The results from the very first user experiment at SwissFEL have just been published in the Proceedings of the National Academy of Sciences (PNAS). The measurements probed the electron transport properties of the cytochrome c protein, which is found in cellular mitochondria. The measurements show that when the Fe atom at the centre of the protein undergoes electronic excitation, for example when it gains or loses and electron, the active centre of the protein undergoes a doming structural rearrangement. This result raises interesting questions about how this structural change is involved in the electron transfer properties of cytochrome c.
Methylbismuth: First observation of an organometallic biradical reactive intermediate
Open shell organometallic bismuth are promising agents for catalytic applications, but difficult to characterize due to their high reactivity. The simplest methylbismuth (Bi-CH3), a biradical species, was in-situ synthesized and spectroscopically characterized for the first time. Electronic and thermochemical properties could be obtained, which will guide future synthetic applications.
The unique interplay between copper and zinc during catalytic carbon dioxide hydrogenation to methanol
The nature of high activity of Cu/ZnO catalyst in methanol synthesis remains the subject of intensive debate. Here, the authors are revisiting carbon dioxide hydrogenation mechanism using high-pressure operando techniques.
Operando X-ray diffraction during laser 3D printing
Ultra-fast operando X-ray diffraction experiments reveal the temporal evolution of low and high temperature phases and the formation of residual stresses during laser 3D printing of a Ti-6Al-4V alloy. The profound influence of the length of the laser-scanning vector on the evolving microstructure is revealed and elucidated.
A la recherche du matériau électroluminescent du futur
A l’Institut Paul Scherrer PSI, des chercheurs ont scruté l’intérieur d’un matériau prometteur pour les diodes organiques électroluminescentes (OLED). Leurs conclusions contribueront au développement de matériaux électroluminescents à très bon rendement lumineux et peu coûteux à la fabrication.
Taking a snapshot of the triplet excited state of an OLED organometallic luminophore using X-rays
In this work, the complementarity of pump-probe experiments at SwissFEL (ALVRA endstation) and at synchrotrons (SuperXAS beamline of SLS and ID09 of ESRF) is used to investigate the triplet excited state of Cu OLED materials. Details about the charge transfer and structural rearrangements in the excited state of this material are revealed and obtained data can be used to verify computational methods for rational development of new OLED materials.
Elucidating the Oxygen Activation Mechanism on Ceria-Supported Copper-Oxo Species Using Time-Resolved X-ray Absorption Spectroscopy
We monitored the dynamic structure of the active sites in a catalyst containing highly dispersed copper-oxo species on ceria during low-temperature CO oxidation using time-resolved X-ray absorption spectroscopy. We quantitatively demonstrate that the CO oxidation mechanism below 90 °C involves an oxygen intermediate strongly bound to the active sites as well as the redox activity of Cu2+/Cu+ and Ce4+/Ce3+ couples.