Review of X-ray scattering methods with synchrotron radiation

Synchrotron light sources provide brilliant light with a focus on the X-ray region and have enormously expanded the possibilities for characterising materials. In the Reviews of Modern Physics, an international team now gives an overview of elastic and inelastic X-ray scattering processes, explains the theoretical background and sheds light on what insights these methods provide in physics, chemistry as well as bio- and energy related themes.

“X-ray scattering can be used to investigate and resolve a wide variety of issues from the properties and excitations of fuctional solids, to homogeneous and heterogeneous chemical processes and reactions or even the proton pathway during the splitting of water,” explains Prof. Dr. Alexander Föhlisch, who heads the Institute Methods and Instrumentation for Research with Synchrotron Radiation at HZB.

Read more on the HZB website

Image: Resonant X-ray excitation (purple) core excites the oxygen atom within a H2O molecule. This causes ultrafast proton dynamics. The electronic ground state potential surface (bottom) and the bond dynamics is captured by distinct spectral features in resonant inelastic X-ray scattering (right).

Credit: © Martin Künsting /HZB

Grain-scale deformation of a high entropy alloy


New research that exploited the unique strengths of the FAST beamline produced some of the first measurements of individual grain deformation in high entropy alloys. This data can help form accurate predictions of damage and failure processes in these emerging materials, critical for understanding their performance in real-world applications.

Grains and strains | A subset of the thousands of indexed grains are shown, along with their axial elastic strains (top) and maximum resolved sheer stress (bottom), at 4 positions indicated on the stress-strain curve. This microscopic detail is only available via high-energy x-ray techniques.

What is the discovery?


Conventional alloys are made primarily of one metal element, with a small substitution of other atoms to tune the properties (for example, 7.5% Cu and 92.5% Ag produces sterling silver). Recently, new types of high entropy alloys (HEAs) have been discovered, which are made by mixing many different metallic elements in nearly-equal proportions. HEAs can exhibit remarkably different properties from conventional alloys. In a new paper, a team lead by Jerard Gordon from the University of Michigan reports a high-energy x-ray study of the HEA made from mixing equal amounts of Co, Cr, Fe, Mn, and Ni. The team was able to use far-field high-energy diffraction microscopy (ff-HEDM) to understand the microscopic response of thousands of individual crystal grains in their sample when it is deformed under load. They were also able to compare the results with detailed crystal-plasticity models.

Read more on the CHESS website

Image: Grains and strains | A subset of the thousands of indexed grains are shown, along with their axial elastic strains (top) and maximum resolved sheer stress (bottom), at 4 positions indicated on the stress-strain curve. This microscopic detail is only available via high-energy x-ray techniques.

Tuning the magnetic anisotropy of lanthanides

The magnetism of lanthanide-directed nanoarchitectures on surfaces can be drastically affected by small structural changes. The study carried out in a collaboration between researchers from IMDEA Nanociencia and BOREAS beamline at ALBA reports the effect of the coordination environment in the reorientation of the magnetic easy axis of dysprosium-directed metal-organic networks on Cu(111). The authors show that the magnetic anisotropy of lanthanide elements on surfaces can be tailored by specific coordinative metal-organic protocols.

Recent findings have highlighted the potential of lanthanides in single atom magnetism. The stabilization of single atom magnets represents the ultimate limit on the reduction of storage devices. However, single standing atoms adsorbed on surfaces are not suitable for practical applications due to their high diffusion, i.e., low thermal stability. The next step towards more realistic systems is the coordination of these atoms in metal-organic networks.In 4f elements, the spin-orbit coupling (SOC) is larger than the crystal field, which might result in higher anisotropies. Furthermore, the crystal field acts as a perturbation of the SOC and can be tailored to increase the anisotropy by choosing an appropriate coordination environment. The strong localization of the 4f states reduces the hybridization with the surface, increasing the spin lifetimes, which is crucial, since a long magnetic relaxation time is mandatory for technological applications.

Read more on the ALBA website

Image: Cover picture showing the structure of the Dy-TPA network where C, H, O and Dy atoms are represented by black, red and green balls, respectively, the tilted orientation of the magnetic easy axis is represented by green arrows. 

Credit: ALBA

Developing antiviral drugs to treat COVID-19 infections

The rapid development of safe and effective vaccines has helped bring the pandemic under control. However, with the rise of variants and an uneven global distribution of vaccines, COVID-19 is a disease we will have to manage for some time.

Antiviral drugs that target the way the virus replicates may be the best option for treating outbreaks of COVID-19 in unvaccinated and under-vaccinated populations.

Using the Canadian Light Source (CLS) at the University of Saskatchewan, researchers from the University of Alberta (U of A) have isolated some promising inhibitors that could be used to treat COVID-19 infections. The scientists used the synchrotron remotely during the facility’s special COVID-19 call for proposals, an initiative created to support research to help fight the pandemic.

The team’s findings have been recently published in the European Journal of Medicinal Chemistry.

“With the help of the CLS, and the multiple teams here at the U of A, including the our lab and the Young lab in the Department of Biochemistry, Vederas lab in the Department of Chemistry, and Tyrrell team in Medical Microbiology and Immunology Department, we’ve been very efficient at developing a group of inhibitors that is very promising,” said Joanne Lemieux, a professor at the U of A.

Read more on the CLS website

Image: Michel Fodje, CLS Senior Scientist, using the CMCF beamline at the CLS, which was used for this project.

Credit: Canadian Light Source

Green hydrogen: Why do certain catalysts improve in operation?

Crystalline cobalt arsenide is a catalyst that generates oxygen during electrolytic water splitting in the production of hydrogen. The material is considered to be a model system for an important group of catalysts whose performance increases under certain conditions in the course of electrolysis. Now a HZB-team headed by Marcel Risch has observed at BESSY II how two simultaneous mechanisms are responsible for this. The catalytic activity of the individual catalysis centres decreases in the course of electrolysis, but at the same time the morphology of the catalyst layer also changes. Under favourable conditions, considerably more catalysis centres come into contact with the electrolyte as a result, so that the overall performance of the catalyst increases.

As a rule, most catalyst materials deteriorate during repeated catalytic cycles – they age. But there are also compounds that increase their performance over the course of catalysis. One example is the mineral erythrite, a mineral compound comprising cobalt and arsenic oxides with a molecular formula of (Co3(AsO4)2∙8H2O). The mineral stands out because of its purple colour. Erythrite lends itself to accelerating oxygen generation at the anode during electrolytic splitting of water into hydrogen and oxygen.

Read more in the HZB website

Image: Schematic of the electrochemical restructuring of erythrite. The fine needle-like structure melts during the conversion from a crystalline material to an amorphous one, which is porous like a Swiss cheese.

Credit: © HZB

Astonishing diversity: Semiconductor nanoparticles form numerous structures

X-ray study reveals how lead sulphide particles self-organise in real time

The structure adopted by lead sulphide nanoparticles changes surprisingly often as they assemble to form ordered superlattices. This is revealed by an experimental study at PETRA III. A team led by the DESY scientists Irina Lokteva and Felix Lehmkühler, from the Coherent X-ray Scattering group headed by Gerhard Grübel, has observed the self-organisation of these semiconductor nanoparticles in real time. The results have been published in the journal Chemistry of Materials. The study helps to better understand the self-assembly of nanoparticles, which can lead to significantly different structures.

Among other things, lead sulphide nanoparticles are used in photovoltaic cells, light-emitting diodes and other electronic devices. In the study, the team investigated the way in which the particles self-organise to form a highly ordered film. They did so by placing a drop of liquid (25 millionths of a litre) containing the nanoparticles inside a small cell and allowing the solvent to evaporate slowly over the course of two hours. The scientists then used an X-ray beam at the P10 beamline to observe in real time what structure the particles formed during the assembly.

To their surprise, the structure adopted by the particles changed several times during the process. “First we see the nanoparticles forming a hexagonal symmetry, which leads to a nanoparticle solid having a hexagonal lattice structure,” Lokteva reports. “But then the superlattice suddenly changes, and displays a cubic symmetry. As it continues to dry, the structure makes two more transitions, becoming a superlattice with tetragonal symmetry and finally one with a different cubic symmetry.” This sequence has been never revealed before in such detail.

Read more on the DESY website

Image: The lead sulphide nanoparticles, which are about eight nanometres (millionths of a millimetre) in size, initially arrange themselves into a layer with hexagonal symmetry

Credit: (Credit: University of Hamburg, Stefan Werner)

Scientists show the first step of turning CO2 into fuel in two very different ways

Their work aims to bridge two approaches to driving the reaction – one powered by heat, the other by electricity – with the goal of discovering more efficient and sustainable ways to convert carbon dioxide into useful products.

Virtually all chemical and fuel production relies on catalysts, which accelerate chemical reactions without being consumed in the process. Most of these reactions take place in huge reactor vessels and may require high temperatures and pressures.

Scientists have been working on alternative ways to drive these reactions with electricity, rather than heat. This could potentially allow cheap, efficient, distributed manufacturing powered by renewable sources of electricity.

But researchers who specialize in these two approaches – heat versus electricity – tend to work independently, developing different types of catalysts tailored to their specific reaction environments.

Read more on SLAC website

Image: This illustration shows one of the active sites of a new catalyst that accelerates the first step in making fuels and useful chemicals from carbon dioxide. The active sites consist of nickel atoms (green) bonded to nitrogen atoms (blue) and scattered throughout a carbon material (gray). SLAC and Stanford researchers discovered that this catalyst, called NiPACN, works in reactions driven by heat or electricity – an important step toward unifying the understanding of catalytic reactions in these two very different reaction environments.

Credit: (Greg Stewart/SLAC National Accelerator Laboratory)

When vibrations increase on cooling: Anti-freezing observed

An international team has observed an amazing phenomenon in a nickel oxide material during cooling: Instead of freezing, certain fluctuations actually increase as the temperature drops. Nickel oxide is a model system that is structurally similar to high-temperature superconductors. The experiment, which was carried out at the Advanced Light Source (ALS) in California, shows once again that the behaviour of this class of materials still holds surprises.

In virtually all matter, lower temperatures mean less movement of its microscopic components. The less heat energy is available, the less often atoms change their location or magnetic moments their direction: they freeze. An international team led by scientists from HZB and DESY has now observed for the first time the opposite behaviour in a nickel oxide material closely related to high-temperature superconductors. Fluctuations in this nickelate do not freeze on cooling, but become faster.

Read more on the HZB website

Image: The development of this speckle pattern over time reveals microsocopic fluctuations in the material.

Credit: © 10.1103/PhysRevLett.127.057001

Water as a metal

Under normal conditions, pure water is an almost perfect insulator. Water only develops metallic properties under extreme pressure, such as exists deep inside of large planets. Now, an international collaboration has used a completely different approach to produce metallic water and documented the phase transition at BESSY II. The study is published now in Nature.

Every child knows that water conducts electricity – but this refers to “normal” everyday water that contains salts. Pure, distilled water, on the other hand, is an almost perfect insulator. It consists of H2O molecules that are loosely linked to one another via hydrogen bonds. The valence electrons remain bound and are not mobile. To create a conduction band with freely moving electrons, water would have to be pressurised to such an extent that the orbitals of the outer electrons overlap. However, a calculation shows that this pressure is only present in the core of large planets such as Jupiter.

Providing electrons

An international collaboration of 15 scientists from eleven research institutions has now used a completely different approach to produce a aqueous solution with metallic properties for the first time and documented this phase transition at BESSY II. To do this, they experimented with alkali metals, which release their outer electron very easily.

Read more on the HZB website

Image: The picture on the top left shows an NaK drop in a vacuum without water vapour. The other pictures show the development of this drop over time when water vapour is present. Thus, a gold-coloured layer of metallic water forms first, followed by white spots of alkali hydroxide. After about 10 seconds, the drop falls.

Credit: © HZB/Nature

X-ray unveils the creation process of materials on several length scales

Nanostructuring often makes materials very powerful in many applications. Some nanomaterials take on the desired complex structures independently during their creation process. Scientists from the University of Hamburg, DESY, ESRF and the Ludwig Maximilians University in Munich have studied the formation of cobalt oxide crystals just a few nanometers in size and how they assemble, while they are still being formed. The results are published in Nature Communications.

Nanomaterials have special properties that make them more effective than conventional materials in various applications. In sensors and catalysts (in green energy production, such as water splitting into energy-rich hydrogen and oxygen) the important chemical processes happen at the surface. Nanostructured materials, even in small amounts, provide a very large surface and are therefore suitable for this kind of applications.

Further potential arises due to the variety of shapes and material combinations that are conceivable on the nanoscale. However, establishing the exact shape of these nanostructures can be a tedious process. Researchers focus on nanocrystals that independently form complex structures without any external influence, for example by sticking together (assembling). This increases their effectiveness in important technological applications, such as green energy generation or sensor technology.

“Often nanoparticles arrange themselves independently, as if following a blueprint, and take on new shapes,” explains Lukas Grote, one of the main authors of the study and scientist at DESY and the University of Hamburg. “Now, however, we want to understand why they are doing this and what steps they go through on the way to their final form. That is why we follow the formation of nanomaterials in real time using high-intensity X-rays. ” For some of the experiments, the researchers used the European Synchrotron Radiation Facility (ESRF) and DESY’s synchrotron radiation source PETRA III.

Read more on the ESRF website

Image: X-rays from a synchrotron radiation source are both attenuated (absorbed) and deflected (scattered) by matter. Depending on which of these interactions is measured with a certain X-ray technology, conclusions can be drawn about different stages of the development process of a nanomaterial. If you combine both X-ray absorption and X-ray scattering, you can decipher all the steps from the starting material (left) to the fully assembled nanostructures (right).

Credit: Nature Communications

Main Attraction: Scientists Create World’s Thinnest Magnet

The development of an ultrathin magnet that operates at room temperature could lead to new applications in computing and electronics – such as high-density, compact spintronic memory devices – and new tools for the study of quantum physics.

The ultrathin magnet, which was recently reported in the journal Nature Communications, could make big advances in next-gen memory devices, computing, spintronics, and quantum physics. It was discovered by scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley.

“We’re the first to make a room-temperature 2D magnet that is chemically stable under ambient conditions,” said senior author Jie Yao, a faculty scientist in Berkeley Lab’s Materials Sciences Division and associate professor of materials science and engineering at UC Berkeley.

“This discovery is exciting because it not only makes 2D magnetism possible at room temperature, but it also uncovers a new mechanism to realize 2D magnetic materials,” added Rui Chen, a UC Berkeley graduate student in the Yao Research Group and lead author on the study.

Read more on the ALS website

Image: Illustration of magnetic coupling in a cobalt-doped zinc-oxide monolayer. Red, blue, and yellow spheres represent cobalt, oxygen, and zinc atoms, respectively.

Credit: Berkeley Lab

Scientists break record while battling antibiotic resistance

Drug-resistant diseases could cause up to 10 million deaths a year by 2050, according to the World Health Organization. Scientists used the Canadian Light Source (CLS) at the University of Saskatchewan to better understand how current antibiotics work and how we might curb bacterial resistance to these life-saving drugs.

Many new antibiotics are able to kill infection-causing bacteria by binding to these bacteria’s ribosomes, which are the essential machines that make proteins. In order to see exactly what antibiotics do at an atomic level, researchers from McGill University used the CLS to determine the physical structure of a ribosome as it interacted with one of the newest antibiotics.

To understand how some bacteria are already resistant to this new antibiotic, they also determined how the drug interacts with a key bacterial enzyme that causes the resistance. The results were recently published in Nature Communications Biology.

Visualizing the antibiotic bound to the ribosome, which is a complex with 300,000 atoms, was a feat that took the team roughly five years to complete. In the process, the scientists broke the record for the largest structure ever analyzed using the CMCF beamline at the CLS, which is the only facility of its kind in Canada. The previous record, set in 2013, was for a structure six times smaller.

Read more on the CLS website

Image: Dr Albert Berghuis

Credit: Canadian Light Source

The Middle East synchrotron officially opens MS beamline

The 8th of July 2021 marked the inauguration of SESAME’s Materials Science (MS) beamline. The Ambassador of Switzerland to Jordan, H.E. Mr. Lukas Gasser, along with members of his embassy team, and UNESCO’s Representative to Jordan, Ms. Min Jeong Kim, were welcomed to the inaugural ceremony by the Director General of SESAME, Professor Khaled Toukan, and the Directors of SESAME. 

In his welcoming remarks, Khalid Toukan pointed out that the beamline now allowed the users of SESAME to obtain diffraction data of a quality unparalleled in any laboratory in the region.

The MS beamline is heavily based on the MS X04SA beamline previously in operation at the Swiss Light Source, and its donation to SESAME by the Paul Scherrer Institute (PSI) has resulted in SESAME having a powerful and extremely precise tool to investigate matter at the micro-, nano- and atomic-scale.

A ribbon officially inaugurating the beamline was cut by H.E. Mr. Lukas Gasser and Professor Khaled Toukan, together with Ms. Min Jeong Kim.

Work on the MS beamline had started in 2015, with the adaptation of the design of the MS X04SA beamline to the characteristics of SESAME’s machine. In 2016, after receiving the donation of another major component, a detector from the Swiss company Dectris, execution of the project was fast-tracked, and the installation phase took place between 2017 and 2019, which is when SESAME received a diffractometer for the beamline as a donation from the Diamond Light Source. Upon sourcing the necessary equipment, the MS beam was first delivered to SESAME’s experimental station at the end of 2019. Fine tuning and characterization of its performance continued during the Covid-19 pandemic, and in December 2020, the beamline started hosting its first users. A first paper utilizing data taken at the MS beamline has already been published in a high-impact journal.

Read more on the SESAME website

Image: Cutting the ribbon of the MS Beamline (left to right): the Director General of SESAME, Professor Khaled Toukan, the UNESCO Representative to Jordan Ms. Min Jeong Kim, and the Ambassador of Switzerland to Jordan, H.E. Mr. Lukas Gasser   Note: all picture participants are Covid-19 Vaccinated.

Credit: © SESAME 2021

Understanding the physics in new metals

Researchers from the Paul Scherrer Institute PSI and the Brookhaven National Laboratory (BNL), working in an international team, have developed a new method for complex X-ray studies that will aid in better understanding so-called correlated metals. These materials could prove useful for practical applications in areas such as superconductivity, data processing, and quantum computers. Today the researchers present their work in the journal Physical Review X.

In substances such as silicon or aluminium, the mutual repulsion of electrons hardly affects the material properties. Not so with so-called correlated materials, in which the electrons interact strongly with one another. The movement of one electron in a correlated material leads to a complex and coordinated reaction of the other electrons. It is precisely such coupled processes that make these correlated materials so promising for practical applications, and at the same time so complicated to understand.

Strongly correlated materials are candidates for novel high-temperature superconductors, which can conduct electricity without loss and which are used in medicine, for example, in magnetic resonance imaging. They also could be used to build electronic components, or even quantum computers, with which data can be more efficiently processed and stored.

Read more on the BNL website

Image: Brookhaven Lab Scientist Jonathan Pelliciari now works as a beamline scientist at the National Synchrotron Light Source II (NSLS-II), where he continues to use inelastic resonant x-ray scattering to study quantum materials such as correlated metals.

Credit: Jonathan Pelliciari/BNL

Diamond-II programme set to transform UK science

Diamond Light Source has established itself as a world-class synchrotron facility enabling research by leading academic and industrial groups in physical and life sciences. Diamond has pioneered a model of highly efficient and uncompromised infrastructure offered as a user-focussed service driven by technical and engineering innovation.

To continue delivering the world-changing science that Diamond leads and enables, Diamond-II is a co-ordinated programme of development that combines a new machine and new beamlines with a comprehensive series of upgrades to optics, detectors, sample environments, sample delivery capabilities and computing. The user experience will be further enhanced through access to integrated and correlative methods as well as broad application of automation in both instrumentation and analysis. Diamond-II will be transformative in both spatial resolution and throughput and will offer users streamlined access to enhanced instruments for life and physical sciences.

Read more on the Diamond website

Image: Diamond’s synchrotron building

Credit: Diamond Light Source

A new way of controlling skyrmions motion

A group of researchers from France has been able to create and guide skyrmions in magnetic tracks. These nanoscale magnetic textures are promising information carriers with great potential in future data storage and processing devices. Experiments at the CIRCE-PEEM beamline of the ALBA Synchrotron enabled to image how skyrmions move along tracks written with helium ions.

Magnetic skyrmions are local twists of the magnetization, considered as units (bits) in new magnetic data storage devices. They were named after British physicist Tony Hilton Royle Skyrme, who described these whirling configurations in the 80’s. But it was not until 2006 that there was evidence of their existence.

Skyrmions are of great interest for the scientific and industrial community as they could help finding more efficient ways to store and process information in our computers. They can be manipulated with lower electrical currents, opening a path for being used as information carriers.

But skyrmions are difficult to control. They do not move in straight lines when current is injected but naturally drift sideways, “killing” themselves. This is known as the Skyrmion Hall effect. In order to be used in devices, they need to be moved and controlled in a reliable way.

A group of researchers led by Olivier Boulle from SPINTEC (Grenoble, France) has a wide experience on the subject. They already reported in 2016 the first observation of magnetic skyrmions under conditions appropriate to the industrial needs, with experiments done at the ALBA Synchrotron.

Now, they have found a way to create and guide skyrmions in racetracks: by irradiating magnetic ultrathin layers with helium ions. This method enables to locally tune the magnetic properties to the desired point without introducing defects in the layer.

The samples were prepared and its magnetic properties were locally modified by helium ions irradiation to create the tracks. Later, they were characterized with different techniques to ensure the preparation was consistent. At the CIRCE beamline of the ALBA Synchrotron, using the PEEM photoemission electron microscope, they were able to image how skyrmions move along the tracks when receiving current pulses. Results were confirmed with magnetic force microscopy and micromagnetic simulations.

Read more on the ALBA website

Image: Micromagnetic simulation showing skyrmion motion along the irradiated racetrack. The irradiated racetrack confines the skyrmions within and they move with nanosecond (ns) current pulses along the track edge without being annihilated, thereby deminishing the Skyrmion Hall Effect (SkHE) (current densities in the parentheses are in A.m-2).