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Dieser Inhalt ist nicht auf Deutsch verfügbar.microXAS
The mission of the microXAS beamline project is to operate and advance a versatile hard x-ray microprobe facility for multimodal chemical microscopy and micro-spectroscopy. We strive to enhance spatial resolution, and to develop new or superior chemical contrast modes. Over a large range of length (and time) scales, we apply this comprehensive set of X-ray microbeam analytical techniques to scientific challenges in the broader scope of reactive transport in porous media: From virus metabolite distribution in single cells, over the variability of catalytic reactivity in single crystal catalysts, to reactive contaminant transport phenomena in heterogeneous natural porous media.
The scientific and engineering activities directly related to the instrumentation of the microXS beamline facility are complemented by a vivid in-house science program. These research activities link to the development of an advanced understanding of macroscopic reactivity and dynamics of complex systems based on the micro/nanoscopic physical and chemical. The focus subject corresponds to enlightening our understanding of environmental chemical processes – including their link to physics and biology. Special emphasis is devoted to the characterization of chemical reactions occurring at solid-liquid interfaces in undisturbed surface and subsurface environments.
Scientific highlights
Moving Atoms by Photodoping
Understanding how and how fast we can drive atoms to create a structural phase transition is of fundamental interest as it directly relates to many processes in nature. Here we show that a photoexcitation can drive a purely structural phase transition before the energy is relaxed in the material that corresponds to a “warmer” equilibrated state.
Active Sites of supported bimetallic nano-Catalysts
Dynamic Structural Changes of Active Sites in Pt–Ni Bimetallic Catalysts Revealed by a Multimodal Approach
Making the world go round - a look into the structure of a prominent heterogeneous catalyst
Fluid catalytic cracking catalysts, which are composite particles of hierarchical porosity, were examined using ptychographic X-ray tomography. These particles are essential to the conversion of crude oil into gasoline. Examination of catalysts at decreasing levels of catalytic conversion efficacy allowed the detection of possible deactivation causes.
Chemical Imaging to Spy on Malaria Parasites
Unique insights into the adolescence and metabolism of a Malaria parasite in a human red blood cell are obtained by a new chemical imaging methodology – in situ correlative X-ray fluorescence microscopy and soft X-ray tomography.
Fate of Plutonium through a Geological Reactive Barrier
Natural geological and engineered barriers play a key role in protecting the environment and the anthroposphere from the hazardous impact of deposited waste or spreading contaminants. Such natural geological and engineered barrier materials are commonly complex and heterogeneous. In-situ multimodal microscopic studies under conditions relevant to deep geological formations are crucial to identify the reactive components and reaction pathways or to validate proposed immobilization mechanisms. The present study demonstrated that a simplistic description by a sole reactive component is not an adequate representation of the geochemical reactivity responsible for the immobilization of plutonium within a natural Clay Rock barrier. Multimodal chemical imaging studies on intact, undisturbed systems are absolutely essential to ascertain the geochemical reactivity for relevant geochemical conditions and settings.
The chemical state of 79Se in spent nuclear fuel
An interdisciplinary study conducted at different PSI laboratories (LES,AHL, LRS, SYN) in collaboration with Studsvik AB (Sweden) demonstrates that selenium originating from fission in light water reactors is tightly bound in the crystal lattice of UO2. This finding has positive consequences for the safety assessment of high-level radioactive waste repository planned in Switzerland, as it implies (contrary to previous assumptions) that the safety-relevant radionuclide 79Se will be released at extremely low rates during aqueous corrosion of the waste in a deep-seated repository.By Enzo Curti (PSI-LES)
Researchers find key to zinc rich plants to combat malnutrition
The diet in many developing countries is lacking zinc, but researchers have just solved the riddle of how to get more zinc into crop seeds. The discovery has been published in Nature Plants, and the research was led by University of Copenhagen.By Johanne Uhrenholt Kusnitzoff
Watching lithium move in battery materials
In order to understand limitations in current battery materials and systematically engineer better ones, it is helpful to be able to directly visualize the lithium dynamics in materials during battery charge and discharge. Researchers at ETH Zurich and Paul Scherrer Institute have demonstrated a way to do this.