Tag: x-ray spectroscopy

2014 Nobel Prize idea used to reach super-resolution

2014 Nobel Prize idea used to reach super-resolution

In a leap forward for atomic-scale imaging, researchers have introduced a novel X-ray technique that could transform our understanding of electron motion at the microscopic level. This cutting-edge method, developed by an international team of scientists, uses the unique properties of European XFEL at Schenefeld near Hamburg, Germany—the largest X-ray laser in the world—to capture detailed snapshots of atomic interactions. The results of this research were now published in Nature.

The technique, called stochastic Stimulated X-ray Raman Scattering (s-SXRS), turns noise into valuable data, offering snapshots of the electronic structures of atoms. This advancement sets the stage for breakthroughs in chemical analysis and materials science.

Researchers from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, the Max Planck Institute for Nuclear Physics, of European XFEL and others developed this innovative approach to X-ray spectroscopy, achieving unprecedented detail and resolution.

“For a long time, chemists have dreamed of seeing how electrons move when they’re in excited states, as these movements are what drive chemical reactions,” says Linda Young, an Argonne Distinguished Fellow and professor at the University of Chicago. “Our technique brings us closer to realizing that dream.”

The key innovation is a super-resolution technique that greatly improves the detail in X-ray spectroscopy, a method for studying electron placement around atomic centres. This advancement helps scientists identify closely spaced energy levels in atoms, offering a clearer view of their electronic structures, which determine chemical properties.

“Think of it like upgrading from a standard-definition television to an ultra-high-definition screen,” Young explains. “We’re now able to see the fine details of electronic motion that were previously blurred or invisible.”

The practical applications of stochastic Stimulated X-ray Raman Scattering are wide-ranging. For example, it can provide insights into how chemical bonds form or break, offering a deeper understanding of fundamental processes relevant to chemical analysis. This knowledge is essential for developing new materials with specific electronic properties, impacting industries like electronics and nanotechnology.

The researchers directed the X-ray pulses of European XFEL through neon gas and used a spectrometer to collect the resulting radiation. The small, 5-millimeter gas cell was designed by the Max Planck Institute for Nuclear Physics The intense beam created tiny holes in the cell’s entrance and exit windows, allowing the X-rays to pass through to a grating spectrometer—a device that separates light into its different wavelengths—provided by collaborators from Uppsala University in Sweden. The European XFEL experts have taken on a vital role in coordinating the installation and performing thorough pre-experimental testing. “This ensured optimal focusing conditions, which were crucial for efficiently acquiring a large amount of data during the experiment” explains Michael Meyer, group head of the Small Quantum Systems (SQS) instrument at European XFEL and a researcher in the Cluster of Excellence ‘CUI: Advanced Imaging of Matter’.

As the X-rays pass through the gas, they amplify the Raman signals—a type of X-ray fingerprint that provides information about the excited electronic states of atoms or molecules—by nearly a billion-fold. This amplified signal provides detailed information about the electronic structure of the gas on a femtosecond timescale, or one quadrillionth of a second. By analysing the relationship between the incoming pulses and the resulting Raman signals, scientists can create a detailed energy spectrum from many individual snapshots, rather than scanning slowly across different energy levels.

“The large number of pulses in each X-ray flash not only boosts the measurement signal but also holds the key to the highest spectral resolution by averaging over many photon impacts on the detector at once,” says Thomas Pfeifer from the Max Planck Institute for Nuclear Physics.

“This approach, pinpointing the centre position of broad but distinct spectral spikes much more precisely than the width of the spikes, is similar to the super-resolution microscopy technique that won the 2014 Nobel Prize in chemistry”, Pfeifer adds.

Read more on European XFEL website

Image: An incoming X-ray light wave (left) made up of a chaotic distribution of very fast spikes interacts with atoms (purple dots) in a gas to amplify specific spikes (right) in the light wave.

Credit: Illustration by Stacy Huang/Argonne National Laboratory

Aluminium made visible

Aluminium made visible

Zeolites are highly porous substances that facilitate numerous reactions in the chemical industry. In collaboration with the J. Heyrovský Institute of Physical Chemistry in Prague, PSI researchers have succeeded for the first time in precisely determining the position of the aluminium atoms in the zeolite lattice – an important step on the path to tailor-made catalysts. The study has now been published in the journal Science.

In cat litter they absorb unpleasant odours; in detergents they soften the water, protecting washing machines; and in refineries they help in the production of petrol – zeolites are used in many different places. We encounter them in our daily lives, and they are the most frequently used catalysts for promoting chemical reactions in industry. 

Their many useful properties stem from their porous, lattice-like structure. Silicon and aluminium atoms are linked by oxygen atoms to form a crystalline framework with numerous small pores and channels. Zeolites can capture molecules from gases or liquids, hold on to them and help to convert them into other molecules. But it is only now that PSI researchers have managed to draw a more precise picture of a zeolite structure: they have located the position within the lattice of the aluminium atoms that trigger the chemical reactions.

“Zeolites are extremely important materials, but we still don’t fully understand how they work,” says Jeroen van Bokhoven of PSI’s Center for Energy and Environmental Sciences. Previous methods were able to determine the position of the atoms in the lattice but could not distinguish aluminium from silicon. The aluminium atoms play a particularly important role, however: they form the active sites that allow certain reactions to take place. This is why scientists are particularly interested in locating them. 

The exact position of the aluminium atoms determines how effective the zeolite in question is as a catalyst and for which chemical reactions. Different zeolite structures are used for different reactions. The PSI researchers used their method to investigate the zeolite ZSM-5, a particularly important industrial catalyst with an unusually complex structure. “We reckoned that if we could do this with ZSM-5, the other zeolites wouldn’t be a problem,” says Jeroen van Bokhoven.

The SLS as a large microscope

The question of where exactly the aluminium atoms are located in the zeolite structure has long vexed scientists. “The new method we have developed solves a problem that previously seemed unsolvable,” says Przemyslaw Rzepka, first author of the study. Rzepka, who used to work with Jeroen van Bokhoven at PSI as a postdoc, is now a scientist at the J. Heyrovský Institute of Physical Chemistry in Prague. 

Until now, scientists have used ordinary X-rays to look inside zeolites and learn about the structure of their pores and channels. The X-rays are scattered by the atoms and the resulting diffraction pattern allows conclusions to be drawn about the three-dimensional structure of the material. The problem is that the elements silicon and aluminium are right next to each other in the periodic table, and this means that in experiments using ordinary X-rays they look more or less identical. Spectroscopic methods, on the other hand, rely on the way a material absorbs radiation or alters it. Because aluminium and silicon absorb radiation differently, the two types of atoms can be distinguished – however, such methods cannot determine their positions in space, only the number and type of atoms in a material.

The PSI scientists’ solution was to combine the two techniques. They directed soft X-rays, which have comparatively low energies, at the materials at the Swiss Light Source SLS. “The pattern created when the X-rays are scattered by the material tells us the position of the atoms. We then examine these positions using spectroscopic methods to identify the particular type of atom that is sitting there,” explains Przemyslaw Rzepka. 

This clever combination was made possible by the unique X-ray diffractometer for soft X-rays at the SLS Phoenix beamline. The researchers were able to see, for the first time, a difference between silicon and aluminium atoms and determine the exact location of the active sites where the reaction takes place.

Read more on PSI website

Image: Jeroen van Bokhoven (left) and his team at the Paul Scherrer Institute PSI in Villigen are carrying out research into zeolites. His research group has succeeded for the first time in determining the position of the aluminium atoms that are crucial to the catalytic properties of the materials. This was possible thanks to the Swiss Light Source SLS, where scientist Thomas Huthwelker (right) works.

Credit: Paul Scherrer Institute PSI/Markus Fischer

A new dimension of complexity for layered magnetic materials

A new dimension of complexity for layered magnetic materials

When it comes to layered quantum materials, current understanding only scratches the surface; so demonstrates a new study from the Paul Scherrer Institute PSI. Using advanced X-ray spectroscopy at the Swiss Light Source SLS, researchers uncovered magnetic phenomena driven by unexpected interactions between the layers of a kagome ferromagnet made from iron and tin. This discovery challenges assumptions about layered alloys of common metals, providing a starting point for developing new magnetoelectric devices and rare-earth-free motors. 

Patterns are everything. With quantum materials, it’s not just what they’re made of but how their atoms or molecules are organised that gives rise to the exotic properties that excite researchers with their promise for future technologies. 

Graphene showed this to the world: arranged into single layers of a hexagonal lattice, common-or-garden carbon atoms could exhibit extraordinary electronic properties. Research over the last decade has since been dedicated to discovering whether other two-dimensional arrays of atoms, either alone or stacked into a three-dimensional material, can reveal similarly novel behaviours.

The kagome lattice, which takes its name from a type of Japanese basket woven in corner sharing triangles, is another two-dimensional pattern that has excited researchers with its ability to host exotic quantum states, ranging from superconductivity to unconventional magnetism. 

Yet until now, research has focused on electronic and magnetic properties in two-dimensions of the material. The latest results in Fe3Sn2 – a ferromagnetic material made of iron and tin atoms arranged into the intricate kagome pattern – change that.

Read more on the PSI website

Image: The kagome ferromagnet, Fe3Sn2 hosts spin waves – magnetic ripples arising from collective excitations of electron spins (shown here as golden arrows). The new findings reveal that the spin-waves are influenced by unexpected interactions between the layers in the material.

Credit: ©Wenliang Zhang / Paul Scherrer Institute PSI

Environmental pollutants found incrusted in iron in endometriotic lesions

Environmental pollutants found incrusted in iron in endometriotic lesions

Scientists led by Istituto Di Ricovero e Cura a Carattere Scientifico (IRCCS), the Italian Research Hospital Burlo Garofolo in Trieste show that iron presence in endometriosis is associated to the accumulation of environmental metals, supporting the idea that the environment exposure to toxic chemicals plays a role in the disease.

Around 1 in 10 women in reproductive age around the world live with endometriosis, an inflammatory disease caused when tissue similar to the lining of the uterus grows outside the womb, such as in the ovaries and fallopian tubes. This causes pain and, in many cases, infertility. Even if women have always been affected by endometriosis, it is only since recently that the scientific community has started looking into it. 

The factors that may lead to endometriosis go from genetic predisposition to autoimmune diseases and environmental triggers. Now a team from Institute for Maternal and Child health IRCCS Burlo Garofolo in Trieste (Italy) has found the presence of iron clustered with environmental metals, such as lead, aluminium or titanium, using beamlines ID21 and id16B at the ESRF.

The accumulation of iron in endometriosis was already well documented. Iron deposits are common in endometrial lesions, indicating an altered iron metabolism. “We knew that iron can create oxidative stress and hence, inflammation, as it does in other conditions, such as asbestosis, so we wanted to know more about what chemical form it takes, how it is distributed and whether there are other environmental pollutants with it”, explains Lorella Pascolo, leader of the study. 

Pascolo and her team came to the ESRF to compare iron nanoaggregates in endometrial lesions of patients with normal endometrium samples of the same patients. “The ESRF beamlines are exceptional instruments to get a clear picture of the role of iron and how it transforms into endometrial lesions”, explains Pascolo. 

They used X-ray fluorescence (XRF) on beamline ID21 to track the presence and distribution of iron and environmental pollutants, and ID16B to fine-tune the findings and reveal additional heavy metals at the nano level. They also used X-ray spectroscopy to reveal the chemical state of the iron. 

Read more on the ESRF website

Influence of protons on water molecules

Influence of protons on water molecules

How hydrogen ions or protons interact with their aqueous environment has great practical relevance, whether in fuel cell technology or in the life sciences. Now, a large international consortium at the X-ray source BESSY II has investigated this question experimentally in detail and discovered new phenomena. For example, the presence of a proton changes the electronic structure of the three innermost water molecules, but also has an effect via a long-range field on a hydrate shell of five other water molecules.

Excess protons in water are complex quantum objects with strong interactions with the dynamic hydrogen bond network of the liquid. These interactions are surprisingly difficult to study. Yet so-called proton hydration plays a central role in energy transport in hydrogen fuel cells and in signal transduction in transmembrane proteins. While the geometries and stoichiometries have been extensively studied both in experiments and in theory, the electronic structure of these specific hydrated proton complexes remains a mystery.

A large collaboration of groups from the Max Born Institute, the University of Hamburg, Stockholm University, Ben Gurion University and Uppsala University has now gained new insights into the electronic structure of hydrated proton complexes in solution.

Using the novel flatjet technology, they performed X-ray spectroscopic measurements at BESSY II and combined them with infrared spectral analysis and calculations. This allowed them to distinguish between two main effects: Local orbital interactions determine the covalent bond between the proton and neighbouring water molecules, while orbital energy shifts measure the strength of the proton’s extended electric field.

Read more on the HZB website

Image: The spectral fingerprints of water molecules could be studied at BESSY II. The result: the electronic structure of the three innermost water molecules in an H7O3+ complex is drastically changed by the proton. In addition, the first hydrate shell of five other water molecules around this inner complex also changes, which the proton perceives via its long-range electric field.

Credit: © MBI

When vibrations increase on cooling: Anti-freezing observed

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

Riverine iron survives salty exit to sea

Riverine iron survives salty exit to sea

Iron organic complexes in Sweden’s boreal rivers significantly contribute to increased iron concentration in open marine waters, X-ray spectroscopy data shows. A Lund University study in Biogeosciences characterizes the role of salinity for iron-loading in estuarine zones, a factor which underpins intensifying seasonal algal blooms in the Baltic Sea.

The study ties in with a reported trend of increased riverine iron concentrations over the last decade in North America, northern Europe and in particular, Swedish and Finnish rivers. This, in conjunction with a predicted rise in extreme weather events in Scandinavia due to climate change, provides momentum for more bioavailable iron to enter marine environments such as the Baltic Sea.

“The consequences of increasing riverine iron for the receiving [marine] system depend first and foremost on the fate of iron in the estuarine salinity gradient. We had questions on what factors determine the movement and transport capacity of iron in these boreal rivers,” said Simon Herzog, postdoctoral researcher at Lund University.

The research group investigated the iron discharge in eight boreal rivers in Sweden which drain into the Baltic Sea, a brackish marine system. Water samples were taken upstream and at the river mouths, the latter just before estuarine mixing and stronger saline conditions occur. Spring and autumn specimens enabled the comparative analysis of flow conditions. To determine the type and amounts of iron species, measurements with X-ray absorbance spectroscopy (XAS) were taken at beamline I811 at Max-lab in Lund, Sweden and X-ray Absorption Near-Edge Structure (XANES) spectra at beamline ID26 at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France.

Read more on the MAX IV website

Image: A view of the Ore River in northern Sweden

Credit: Simon Herzog

Electron and X‑ray Focused Beam-Induced Cross-Linking in Liquids:

Electron and X‑ray Focused Beam-Induced Cross-Linking in Liquids:

Toward Rapid Continuous 3D Nanoprinting and Interfacing using Soft Materials

Modern additive fabrication of three-dimensional (3D) micron to centimeter size constructs made of polymers and soft materials has immensely benefited from the development of photocurable formulations suitable for optical photolithography,holographic,and stereolithographymethods. Recent implementation of multiphoton laser polymerization and its coupling with advanced irradiation schemes has drastically improved the writing rates and resolution, which now approaches the 100 nm range. Alternatively, traditional electron beam lithography and its variations such as electron-beam chemical lithography, etc. rely on tightly focused electron beams and a high interaction cross-section of 0.1−10 keV electrons with the matter and have been routinely used for complex patterning of polymer resists, self-assembled monolayers, and dried gel films with up to a few nanometers accuracy.

Similarly, a significant progress has been made in deep X-ray lithography, direct writing with zone plate focused X-ray beams for precise, and chemically selective fabrication of high aspect ratio microstructures. Reduced radiation damage within the so-called “water window” has spurred wide biomedical X-ray spectroscopy, microscopy, and tomography research including material processing, for example, gels related controlled swelling and polymerization inside live systems, particles encapsulations,and high aspect ratio structures fabrication.The potential of focused X-rays for additive fabrication through the deposition from gas-phase precursors or from liquid solutions is now well recognized and is becoming an active area of research.

Read more on the Elettra website

Image: The electron/X-ray beam gelation in liquid polymer solution through a SiN ultrathin membrane. Varying the energy and focus of the soft X-rays smaller or larger excitation volumes and therefore finer or wider feature sizes and patterns can be generated.