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.
Full-field X-ray absorption tomography reveals the chemical structure of defects in metal-organic frameworks
Cryo-full-field XANES computed tomography was used to visualize the presence and distribution of a second coordination polymer of reduced copper coordination within defect-engineered HKUST-1 MOF crystals. Observations encourage a revisitation of the structure-property relationships of defect-engineered MOFs.
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.
Lithium ion batteries (LIB) are essential in modern everyday life, with increasing interest in enhancing their performance and lifetime. Secondary particles of Li-rich cathode material were examined with correlated ptychographic X-ray tomography and diffraction microscopy at different stages of cycling to probe the aging mechanism.
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.
Dynamic Structural Changes of Active Sites in Pt–Ni Bimetallic Catalysts Revealed by a Multimodal Approach
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.
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.
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.
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)