Enabling the use of Thin Membranes in Water Electrolyzers using a Recombination Catalyst
The conversion efficiency for green hydrogen production in a polymer electrolyte water electrolyzer (PEWE) is strongly influenced by the ohmic cell resistance and therefore the thickness of the membrane used. The use of thin membranes (~50 micron or below) is limited by gas crossover of H2 and O2, which can lead to the formation of explosive gas mixtures. The incorporation of a recombination catalyst provides remedy and allows a more dynamic operating mode.
Light springs and magnetic vortices: a new kind of dichroism
In contrast to circular dichroism that is dependent on the polarization, helicoidal dichroism induced by a twisted wave front profile is scarcely known. The first evidence of magnetic helicoidal dichroism has now been observed in an experiment using Spiral Fresnel Zone Plates developed at the Paul Scherrer Institut.
Exchange scaling of ultrafast angular momentum transfer in 4f antiferromagnets
A novel approach to controlling the speed of magnetic processes has been found through resonant magnetic scattering in an antiferromagnetic Lanthanide intermetallics.
Higgs-boson pair production at LHC: reliable theoretical uncertainties
Researchers at PSI have refined the theoretical prediction for the pair production of Higgs bosons at the LHC and re-analized the related uncertainties resulting in sizable contributions neglected before. This process will be highly relevant at the high-luminosity run of the LHC to measure the Higgs potential directly.
Waves on circular paths
Just as electrons flow through an electrical conductor, magnetic excitations can travel through certain materials. Such excitations, known in physics as "magnons" in analogy to the electron, could transport information much more easily than electrical conductors. An international research team has now made an important discovery on the way towards such components, which could be highly energy-efficient and considerably smaller.
Optical Setup for a Piston-Cylinder Pressure Cell: A Two-Volume Approach
Measurement of the absolute value of the applied pressure in high-pressure muon and neutron experiments is a complicated task. It often requires the presence of a calibration material inside the sample volume, and could also cause additional time to obtain the response of the calibrant. Here we describe the use of optical calibrants for precise determination of the pressure value inside the piston-cylinder clamp cells.
CNRS movie on n2EDM
Our French collaborators and CNRS produced an excellent short movie about our common n2EDM experiment. The apparatus is currently being set up in
UCN Area South. The collaboration is on track for commissioning of the apparatus with neutrons towards the end of 2022.
Operando X-ray Tomographic Microscopy of Polymer Electrolyte Fuel Cell Freeze Start
Understanding the water management in polymer electrolyte fuel cells (PEFCs) during sub-zero operation is crucial for designing effective freeze start strategies. In collaboration with Toyota Motor Europe sub-second X-ray tomographic microscopy was used to study the water distributions in the gas diffusion layer (GDL) of PEFCs during dynamic freeze starts from −30 °C that mimic automotive freeze start conditions at different pre-drying levels and varying the feed gas humidity.
Cu-doping effects on the ferromagnetic semimetal CeAuGe
We present a study of Cu-substitution effects in 4f-Ce intermetallic compound CeAu1-xCuxGe, with potentially unusual electronic states, in the whole concentration range (x = 0.0 – 1.0). The parent CeAuGe compound, crystallizing in a non-centrosymmetric hexagonal structure, is a ferromagnetic semimetal with Curie temperature 10 K. Cu-doping on Au-site of CeAuGe, CeAu1-xCuxGe, changes the crystal structure from the non-centrosymmetric (P63mc) to centrosymmetric (P63/mmc) space group at the concentration x ∼ 0.5, where the c-lattice constant has a maximum value. Magnetic susceptibility and electrical resistivity measurements reveal that all Cu-doped compounds undergo magnetic phase transition near 10 K, with the maximum transition temperature of 12 K for x = 0.5. The neutron powder diffraction experiments show the ferromagnetic ordering of Ce3+ magnetic moments with a value of about 1.2 μB at 1.8 K, oriented perpendicular to the hexagonal c-axis. By using symmetry analysis, we have found the solutions for the magnetic structure in the ferromagnetic Shubnikov space groups Cmc'21′ and P21′/m' for x < 0.5 and x ≥ 0.5, respectively. Electrical resistivity ρ(T) exhibits a metallic temperature behaviour in all compositions. The resistivity ρ(T) has a local minimum in the paramagnetic state due to Kondo effects at high doping x = 0.8 and 1.0. At the small Cu-doping level, x = 0.2, the resistivity shows a broad feature at the ferromagnetic transition temperature and an additional transition-like peculiarity at 2.5 K in the ferromagnetic state.
Antiferromagnetic excitonic insulator state in Sr3Ir2O7
Excitonic insulators are usually considered to form via the condensation of a soft charge mode of bound electron-hole pairs. This, however, presumes that the soft exciton is of spin-singlet character. Early theoretical considerations have also predicted a very distinct scenario, in which the condensation of magnetic excitons results in an antiferromagnetic excitonic insulator state. Here we report resonant inelastic x-ray scattering (RIXS) measurements of Sr3Ir2O7.
Lighting up the appealing world of hybrid perovskites
Researchers from Italy, in collaboration with the Paul Scherrer Institut, successfully used the macromolecular crystallography beamline X06DA-PXIII at the Swiss Light Source to characterize promising perovkites materials used in solar cells and other photodetector devices.
Low-energy spin dynamics in rare-earth perovskite oxides
A team of scientists from Paul Scherrer Institut and Oak Ridge National Laboratory review recent experimental studies of spin dynamics in the rare-earth perovskite materials. These compounds show unconventional magnetic excitations at low temperatures, including confined and deconfined spinons as well as multimagnon states, which were revealed by means of high-resolution neutron spectroscopy. These observations demonstrate that the rare-earth perovskite magnets can provide realizations of various aspects of quantum low-dimensional physics.
New insight into unconventional superconductivity
Signatures for a novel electronic phase that enables charge to flow spontaneously in loops have been observed in a kagome superconductor. The findings are published today in Nature.
Optimization of catalyst performance to increase efficiency of methanol production
Many types of catalysts have been well known for decades, but the fundamental understanding as to why they work so well is still not quite clear. Without this understanding, an even more efficient catalyst cannot be developed, which is needed to reduce the global energy demand. Copper-zinc-alumina (CZA) is a popular catalyst and has been used for about 100 years, as it facilitates the production of the important chemical building block methanol, a molecule that enables the storage of hydrogen in a manner that minimizes negative impact on the carbon-dioxide footprint. Until 2021, scientists debated over the reason why the catalyst works so well. Understanding the reason behind this is vital in order to further develop even better ones. The copper-zinc-alumina (CZA) catalyst is assessed at the Laboratory for catalysis and sustainable chemistry (LSK) of the Paul Scherrer Institute.
Exploring the role of structural distortions to obtain Cu photosensitizer with thousand times longer excited state lifetime
Cu diimine complexes present a noble metal free alternative to classical Ru, Re, Ir and Pt based photosensitizers in solution photochemistry, photoelectrochemical or dye-sensitized solar cells. Optimization of these dyes requires an understanding of factors governing the key photochemical properties: excited state lifetime and emission quantum yield. Using pump-probe XAS and DFT calculations we have explored the involvement of exciplex formation in the deactivation of the photoexcited state.
Muon spin spectroscopy
Muons are particles with a spin of 1⁄2 that can be implanted into a wide range of condensed matter materials to act as a local probe of the surrounding atomic environment. Measurement of the muon’s precession and relaxation provides an insight into how it interacts with its local environment. From this, unique information is obtained about the static and dynamic properties of the material of interest ...
Taking good and safe care of the retired … nuclear fuel
After several years of loyal and reliable services during heavy duty operation in a reactor, nuclear fuel must be discharged and go into retirement. For Switzerland, the final place of retirement is planned to consist of a deep geological repository where the used nuclear fuel will be disposed. Before the repository is constructed, the used fuel will need to be stored in wet pools and/or dry storage casks.
During all this time, safe handling of the fuel will remain the top priority for operators and regulators. To gain better knowledge on the relevant phenomena which could potentially affect the fuel thermo-mechanics and safety characteristics during long storage periods as well as to allow predicting their evolution, simulation models are being developed at PSI within the DRYstars project.
A first milestone was recently achieved with the development of models coupled to state-of-the-art fuel performance codes for each of the three main categories of phenomena considered as having high safety relevance for storage, namely helium behaviour, creep behaviour and hydrogen behaviour.
Direct observation of crack formation mechanisms with operando Laser Powder Bed Fusion X-ray radiography
Operando high-speed X-ray radiography experiments reveal the cracking mechanism during 3D laser printing of a Ni superalloy.
Celebrating 25 years of SINQ
On January 17th, 2022, we celebrated the 25th anniversary of the inauguration of the Swiss Spallation Neutron Source SINQ. Today, SINQ is firmly embedded in the European research landscape and has established itself as an important center for neutron research.
Direct evidence of in situ Co-oxyhydroxide formation on the surface of La0.2Sr0.8CoO3-δ water splitting catalyst
We carried out in situ and ex situ ambient pressure X-ray photoelectron spectroscopy (APXPS) experiments on a La0.2Sr0.8CoO3-δ perovskite oxygen evolution reaction (OER) catalyst. The study shows that Sr is leached into the electrolyte after immersion, leading to surface Co active site enrichment. Such a Co-enriched surface evolves into a new phase during operation. With the help of theoretical simulations, such a species is assigned to Co-oxyhydroxide, providing direct evidence of its formation during the OER.
Revealing invisible defects in fusion reactor armor
In an exciting collaboration, Nick Phillips, a PSI Fellow at the cSAXS beamline, reveals nanoscale lattice distortions created by invisible defects in fusion reactor armor. This work develops the current understanding of how the smallest, but most prevalent defects, generated during neutron irradiation behave. The novel Bragg ptychographic approach published in Nature Communications paves the way for fast, robust, 3D Bragg ptychography.
E-fuels and electrification as complementary approaches to achieve climate target
Sustainable, synthetic fuels, so-called e-fuels, can help reduce CO₂ emissions. For their production, electricity from renewable sources is required in order to allow for a close to CO₂-neutral balance. The availability of electricity from renewable sources, which ensures the climate benefits of e-fuels, is currently still limited. “Especially in order to produce on a larger scale, a lot of renewable electricity is needed,” explains Christian Bauer, researcher at the Laboratory for Energy Systems Analysis (LEA) at PSI.
Understanding variant selection and texture in additively manufactured red-gold alloys
Synchrotron X-ray diffraction experiments reveal the presence of a non- negligible amount of tetragonal phase in 3D printed red-gold samples.
Confirming the trilinear form of the optical magnetoelectric effect in the polar honeycomb antiferromagnet Co2Mo3O8
Magnetoelectric phenomena are intimately linked to relativistic effects and also require the material to break spatial inversion symmetry and time-reversal invariance. Magnetoelectric coupling can substantially affect light–matter interaction and lead to non-reciprocal light propagation. Here, we confirm on a fully experimental basis, without invoking either symmetry-based or material-specific assumptions, that the optical magnetoelectric effect in materials with non-parallel magnetization (M) and electric polarization (P) generates a trilinear term in the refractive index...
Precision Measurement of the Lamb Shift in Muonium
We report a new measurement of the n=2 Lamb shift in Muonium. Our result of 1047.2(2.3)stat(1.1)syst MHz comprises an order of magnitude improvement upon the previous best measurement. This value matches ...
3D printed nanomagnets unveil a world of patterns in the magnetic field
Scientists have used state-of-the-art 3D printing and microscopy to provide a new glimpse of what happens when taking magnets to three-dimensions on the nanoscale – 1000 times smaller than a human hair.
Signatures of Weyl Fermion Annihilation in a Correlated Kagome Magnet
The manipulation of topological states in quantum matter is an essential pursuit of fundamental physics and next-generation quantum technology. Here we report the magnetic manipulation of Weyl fermions in the kagome spin-orbit semimetal Co3Sn2S2, observed by high-resolution photoemission spectroscopy. We demonstrate the exchange collapse of spin-orbit-gapped ferromagnetic Weyl loops into paramagnetic Dirac loops under suppression of the magnetic order.
Priority access call for work on combating COVID-19 continues
On January 30th, 2020, the WHO declared the recent outbreak of coronavirus disease 2019 (COVID-19), a public health emergency of international concern. It declared that there is an urgent need to improve our understanding of the newly identified virus and its possible future evolution as well as to contain the spread; to develop precise diagnostics and treatment, and to improve the public health response and patient care.
The COVID priority access call continues and is still open in 2022.
Fingerprint of Copper in Peptides Linked to Alzheimer's Disease
In an interdisciplinary project, researchers from the Laboratory of Nanoscale Biology in BIO and the Laboratory for Condensed Matter in PSD have revealed the reaction between the nitrogen atoms of the amyloid-beta peptide and copper/zinc ions by using soft X-ray absorption spectroscopy.
Reactivity and potential profile across the electrified LiCoO2-Li3PS4 interface probed by operando X-ray photoelectron spectroscopy
All-solid-state lithium batteries are a promising alternative for next generation of safe energy storage devices, provided that parasitic side reactions and the resulting hindrances in ionic transport at the electrolyte-electrode interface can be overcome. Motivated by the need for a fundamental understanding of such interface, we present here real-time measurements of the (electro-)chemical reactivity and local surface potential at the electrified interface Li3PS4 and LiCoO2 using operando X-ray photoelectron spectroscopy.
3D Binary Mesocrystals from Anisotropic Nanoparticles
A team of scientists from Konstanz have developed and characterized micrometre-size binary mesocrystals made from the self-assembly of ironoxide and platinum nanocubes and published their work in Angewandte Chemie International Edition. In collaboration with researchers from Empa and PSI, they used brilliant x-rays at the cSAXS beamline of the Swiss Light Source to characterize the lattice spacing in the crystalline structure of the mesocrystals and complement their results through electron microscopy.
Unravelling the catalyst aging phenomena in vehicle emission control.
PSI has collaborated with catalyst and engine manufacturers to understand the aging phenomena of emission control catalysts. To this end, a diesel oxidation catalyst with a relevant mileage was carefully analysed; the results suggest that a complex combination of poisoning and thermal sintering is the cause of deactivation during driving. A reactor setup was then developed to simulate poisoning and sintering effects for prediction of catalyst durability in time and cost effective manner.
Electronic-structure methods for materials design
The accuracy and efficiency of electronic-structure methods to understand, predict and design the properties of materials has driven a new paradigm in research. Simulations can greatly accelerate the identification, characterization and optimization of materials, with this acceleration driven by continuous progress in theory, algorithms and hardware, and by adaptation of concepts and tools from computer science.
AURORA: from Air pollUtion souRces tO moRtAlity
The Laboratory of Atmospheric Chemistry has initiated innovative data-science-based modelling approaches to discover the most important pollution sources for human health
Anomalous temperature dependence of the experimental x-ray structure factor of supercooled water
Supercooled water scattering signals show an anolmalous structure factor temperature dependence suggesting decreasing density at lowering temperatures below 236 K (-37°C).
Amyloid β 42 fibril structure based on small-angle scattering
Alzheimers disease is one of the major global health challenges. Neuronal cell dysfunction and death are connected to the self-assembly of the amyloid β peptide (Aβ42) into oligomeric and fibrillar aggregates. The fibril surface can catalyze the formation of toxic oligomers via secondary nucleation.
LMN PhD student Martin Heinrich wins poster award
PhD student Martin Heinrich of the Molecular Nanoscience group won the best poster award at the Nano-BW 2021 symposium at Bad Herrenalb (Germany), October 6-7. The symposium is held annually within the research network “Functional Nanostructures” of Baden-Württemberg.
Martin introduced his project in the form of a poster titled “Local Manipulation of Spin Domains in a Multiferroic Rashba Semiconductor”. His project started in July 2021 and is funded by the Swiss Nanoscience Institute (SNI) Basel. The poster award was selected by the vote of all attendees.
PSI maintains its leading role in the CLOUD experiment at CERN
The CLOUD experiment at CERN will be recreating particle formation in key regions of the globe to understand the effects of these particles on regional climates
Deciphering the Mechanism of FEC-induced SEI Formation in Li-ion Batteries
Fluoroethylene-carbonate is often referred to as a film-forming electrolyte additive for Li-ion batteries, resulting in high quality Solid–Electrolyte-Interphase on negative electrode, however, the underlying mechanism, even if thought to be known, has been only clarified due to our targeted experimental design, combining systematic electrochemical, chemical and microscopy characterization techniques. We have shown that first the formation of inorganic LiF-rich particles appear and only later the carbonate-rich film is actually formed.
Unconventional Pressure Dependence of the Superfluid Density in the Nodeless Topological Superconductor α-PdBi2
We investigated the superconducting properties of the topological superconductor α-PdBi2 at ambient and external pressures up to 1.77 GPa using muon spin rotation experiments. The ambient pressure measurements evince a fully gapped s-wave superconducting state in the bulk of the specimen. Alternating current magnetic susceptibility and muon spin rotation measurements manifest a continuous suppression of Tc with increasing pressure.
What you see is what you get: Automated particle detection without the false positives
A new algorithm by PSI researchers enables fast and reliable detection of spherical objects in images with a complex background.
PUBLISHED IN SCIENCE: A surface-promoted redox reaction occurs spontaneously on solvating inorganic aerosol surfaces
Ammonium sulfate has been used as a probe for aerosol particles and investigated in situ by means of ambient pressure X-ray photoelectron spectroscopy. Unexpectedly, when the particles start to absorb water, a spontaneous redox reaction leading to nitrogen and elemental sulfur takes place.
Neurodegenerative disease studied by cryogenic X-ray nanotomography
Hard X-ray cryo-tomography scanning of retina from healthy and inherited blindness specimen paves the way for correlative analysis after imaging at the cSAXS beamline.
Vastly Different Morphologies Dependent on the Growth Temperature
Lithium fluoride is an important material which is technologically exploited in spintronics and organic light emitting devices. It turns out that there is a vast difference between the morphologies of ultrathin lithium fluoride grown on the (100) facet of a silver single crystal. At room temperature dendrites are obtained while at elevated temperature lithium fluoride forms square islands. The system is an interesting model to study the crossover between diffusion limited aggregates and island growth.
Diamond gratings for XFEL amplitude-splitting delay line
A split-and-delay line for XFEL pulses has been built and successfully tested by a team of researchers at the Linac Coherent Light Source. Key X-ray optical elements are two diamond diffraction gratings made at the Paul Scherrer Institut that are used to split and later recombine the intense ultrashort X-ray laser pulses for time-resolved measurements.
Coexistence of structural and magnetic phases in van der Waals magnet CrI3
CrI3 has raised as an important system to the emergent field of two-dimensional van der Waals magnetic materials. However, it is still unclear why CrI3 which has a ferromagnetic rhombohedral structure in bulk, changed to anti-ferromagnetic monoclinic at thin layers. Here we show that this behaviour is due to the coexistence of both monoclinic and rhombohedral crystal phases followed by three magnetic transitions at TC1 = 61 K, TC2 = 50 K and TC3 = 25 K.
Overview of SwissFEL dual-photocathode laser capabilities and perspectives for exotic FEL modes
SwissFEL is a compact, high-brilliance, soft and hard X-ray Free Electron Laser (FEL) facility laser composed of two parallel beam lines seeded by a common linear accelerator (LINAC), and a two-bunch photo-injector. For the injector, an innovative dual-photocathode laser scheme has been developed based on state-of-the-art Ytterbium femtosecond laser systems. We just published an overview of the the SwissFEL Photo Cathode Drive Lasers (PCDL) performance, pulse shaping capabilities as well as the versatility of the systems, which allow many different modes of operation of SwissFEL [1]. The full control over the SwissFEL electron bunch properties via the unique architecture of the PCDL will enable in the future the advent of more advanced FEL modes; these modes are, but not restricted to, the generation of single or trains of sub-fs FEL pulses, multi-color FEL and finally the generation of fully coherent X-ray pulses via laser-based seeding.
Glycation of collagen: Quantifying rates
Collagen is abundant in the connective tissue of human beings, e.g. in tendons, ligament and cornea. Glycation of collagen distorts its structure, renders the extracellular matrix stiff and brittle and at the same time lowers the degradation susceptibility thereby preventing renewal. Based on models and with parameters determined from experimental data, we describe the glycation of type 1 collagen in bovine pericardium derived bio-tissues upon incubation in glucose and ribose. We hope that this contributes to a better quantitative understanding of the effects of diabetes on collagen.