LSF Scientific Highlights and News
Scientists pioneer an approach called self-referenced streaking, clocking Auger electrons with sub-femtosecond resolution. The breakthrough will unlock the broader potential for attosecond time resolution at X-ray free-electron lasers.
La spectroscopie de rayons X in operando permet de jeter un coup d’œil à l’intérieur de réacteurs chimiques en fonction. Des chercheurs de l’Institut de technologie de Karlsruhe (KIT), à l’Institut Paul Scherrer PSI et à l’European Synchrotron Radiation Facility (ESRF) en France, appliquent avec succès cette méthode.
Key activity descriptors of nickel-iron oxygen evolution electrocatalysts in the presence of alkali metal cations
Ni-Fe oxyhydroxide is among the most active oxygen evolution electrocatalysts. Electrolyte alkali metal cations modify the activity and reaction intermediates, however, the exact mechanism is at question due to unexplained deviations from the cation size trend. Our X-ray absorption spectroelectrochemical results show that the OER activity follows the variations in .electrolyte pH rather than a specific cation. Our DFT-based reactivity descriptors confirm the conclusions of an indirect pH effect.
The Ružička Prize 2020 goes to Dr. Patrick Hemberger (PSI) for his research on understanding the mechanisms of catalytic fast pyrolysis by unveiling reactive intermediates in heterogeneous catalysts.
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.
The first endstation at the SwissFEL Athos soft X-ray branch is rapidly developing and on track for first experiments in 2021.
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.
A fundamental understanding of the active sites in technical CoMo/ Al2O3 catalysts is crucial to improve the production of clean transportation fuels by hydrodesulfurization (HDS), which removes sulfur from fossil fuels. Sulfur dioxide, resulting from fossil fuel combustion, is one of the main causes for acid rain. In situ X-ray spectroscopic experiments at the SuperXAS beamline of the SLS provided insight in the structure and number of active sites (“Co−Mo−S”) in sulfided CoMo/ Al2O3 catalysts. When the Co to Mo ratio is less than 0.1, cobalt forms isolated sites on the MoS2 phase, where the cobalt promoter atoms are in centrosymmetric octahedral coordination with six-sulfur ligands.
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.