World record in tomography: watching how metal foam forms

An international research team at the Swiss Light Source (SLS) has set a new tomography world record using a rotary sample table developed at the HZB.

With 208 three-dimensional tomographic X-ray images per second, they were able to document the dynamic processes involved in the foaming of liquid aluminium. The method is presented in the journal Nature Communications.
The precision rotary sample table designed at the HZB rotates around its axis at several hundred revolutions per second with extreme precision. The HZB team headed Dr. Francisco García-Moreno combined the rotary sample table with high-resolution optics and achieved a world record of over 25 tomographic images per second using the BESSY II EDDI beamline in 2018.

>Read more on the Bessy II at HZB wesbite

Image: The precision rotary sample table designed at the HZB turns around its axis at several hundred revolutions per second with extreme precision.
Credit: © HZB

Superfluorescent emission in the UV range

Free-electron laser FLASH coaxes superfluorescent emission from the noble gas xenon

Scientists have for the first time induced superfluorescence in the extreme ultraviolet range. Superfluorescence, or superradiance, could be used to build a laser that does not require an optical resonator. The team headed by DESY’s lead scientist Nina Rohringer used DESY’s free-electron laser FLASH to stimulate xenon, a noble gas, inside a narrow tube, causing it to emit coherent radiation, like a laser. The research team is now presenting its work in the journal Physical Review Letters.

“The phenomenon of superfluorescence was first discovered in the microwave range in the 1970s, and then demonstrated for infrared and optical wavelengths too,” explains Rohringer. “In the meantime, superfluorescence has also been observed in the X-ray domain, and at one time this mechanism was believed to be a promising candidate for building X-ray lasers. Until now, however, superfluorescence had not been demonstrated in the extreme ultraviolet, or XUV, range.”

In superfluorescence, the incident light is amplified and emitted along the axis of the medium as a narrow beam of coherent radiation, like in a laser. To produce superfluorescence in the XUV spectrum, the incoming light needs to have enough energy to knock the electrons out of the inner shell of the atoms that make up the lasing medium. Redistribution within the electron shell (Auger decay) leads to a situation in which more particles find themselves in an excited state than in an unexcited state. Physicists refer to this as population inversion.

>Read more on the FLASH at DESY website

Image: The xenon superfluorescence shows up as a bright line (yellow) superimposed on the averaged free-electron laser spectrum (purple, averaged over many shots).
Credit: European XFEL, Laurent Mercadier

“Invisible ink” on antique Nile papyrus revealed by multiple methods

Researchers from the Egyptian Museum and Papyrus Collection, Berlin universities and Helmholtz-Zentrum Berlin studied a small piece of papyrus that was excavated on the island of Elephantine on the River Nile a little over 100 years ago.

The team used serval methods including non-destructive techniques at BESSY II. The researchers’ work, reported in the Journal of Cultural Heritage, blazes a trail for further analyses of the papyrus collection in Berlin.

The first thing that catches an archaeologist’s eye on the small piece of papyrus from Elephantine Island on the Nile is the apparently blank patch. Researchers from the Egyptian Museum, Berlin universities and Helmholtz-Zentrum Berlin have now used the synchrotron radiation from BESSY II to unveil its secret. This pushes the door wide open for analysing the giant Berlin papyrus collection and many more.

>Read more on the BESSY II at HZB website

Illustration: A team of researchers examined an ancient papyrus with a supposed empty spot. With the help of several methods, they discovered which signs once stood in this place and which ink was used.
Credit: © HZB

Visualizing electrostatic gating effects in two-dimensional heterostructures

Electronic and optoelectronic devices utilise electric fields to manipulate material properties, controlling band structures and band alignments across heterostructures that combine metals, semiconductors and insulators. With two-dimensional materials, 2D heterostructures (2DHS) can be fabricated with atomic precision by simply stacking layers. In these, applied out-of-plane electric fields are a powerful tool that can be used to degenerately dope semiconductors, modify electronic structure through the Stark effect, and alter band-alignments between layers. As a result, out-of-plane electric fields have been used to engineer functional architectures such as high-efficiency light-emitting diodes and tunnelling transistors, and to probe many-body phenomena.
Despite the fundamental importance of electric-field control over band structure, direct experimental measurements are challenging and have been limited. Whilst gate electrodes are routinely applied for electrical transport investigations, and many studies have reported electric-field dependent light-emission from 2DHS, these depend upon but do not directly reveal the single-particle electronic structure. Angle resolved photoemission spectroscopy (ARPES) has proven to be a powerful tool for probing the momentum-resolved valence band structure of 2D materials such as graphene and semiconducting transition metal dichalcogenides (MX2). But it is challenging to apply conventional ARPES, which typically averages over lengthscales > 100 µm, to 2DHS which are usually only a few µm across. Using the high spatial resolution and flux of the Spectromicroscopy beamline at Elettra, we have shown that submicrometre spatially resolved ARPES (µARPES) can determine band parameters and band alignments across 2DHS of mechanically exfoliated flakes. These heterostructures are similar to those used for optical spectroscopy and transport measurements, opening the way to study operating devices.

>Read more on the Elettra website

Illustration: Direct momentum-resolved electronic structure measurements of in-operando microelectronic devices.

How morphing materials store information

Experiments at SLAC’s X-ray laser reveal in atomic detail how two distinct liquid phases in these materials enable fast switching between glassy and crystalline states that represent 0s and 1s in memory devices.

Instead of flash drives, the latest generation of smart phones uses materials that change physical states, or phases, to store and retrieve data faster, in less space and with more energy efficiency. When hit with a pulse of electricity or optical light, these materials switch between glassy and crystalline states that represent the 0s and 1s of the binary code used to store information.
Now scientists have discovered how those phase changes occur on an atomic level.
Researchers from European XFEL and the University of Duisburg-Essen in Germany, working in collaboration with researchers at the Department of Energy’s SLAC National Accelerator Laboratory, led X-ray laser experiments at SLAC that collected more than 10,000 snapshots of phase-change materials transforming from a glassy to a crystalline state in real time.

>Read more on the LCLS at SLAC website

Image: The research team after performing experiments at SLAC’s Linac Coherent Light Source X-ray laser.
Credit: Klaus Sokolowski-Tinten/University of Duisburg-Essen)

Please read also the article published on the EUXFEL website:
Rigid bonds enable new data storage technology

Potassium hunting on protein factories

Amazing insights into the location of elusive potassium ions on bacterial ribosomes

Groundbreaking research at the new long-wavelength macromolecular crystallography beamline (I23) at Diamond Light Source has for the first time demonstrated the location of potassium ions in bacterial ribosomes. Ribosomes are the protein factories of cells and although they are vital for life, little was known of the sites of metal ions that are crucial for their structure and function. The work recently published in Nature Communications showcases the fantastic applications of the I23 beamline and sheds light on the important role of potassium ions.

>Read more on the Diamond Light Source website

Image: (extract, full image here) 70S ribosome elongation complex (potassium atoms rendered as green spheres).

Taiwan-Germany experimental facility

National Synchrotron Radiation Research Center (NSRRC) announces that a new, state-of-the-art experimental facility – TPS 45A Submicron Soft X-ray Spectroscopy Beamline, is officially opened. As one of the beamlines at the Taiwan Photon Source (TPS), it delivers soft X-ray with high brilliance, low emittance, and ultra-high spectra resolution, which is ideal for studying and developing novel materials, such as superconducting, nano and magnetic materials.
The ceremony was addressed by Deputy Minister Yu-Chin Hsu of the Ministry of Science and Technology (MOST), Director Gwo-Huei Luo of NSRRC, Chien-Te Chen (member of the NSRRC Board of Director), Director Liu Hao Tjeng of Max Planck Institute for Chemical Physics of Solids (MPI CPfS), Vice President Chii-dong Ho of Tamkang University (TKU), Director Thomas Prinz of German Institute Taipei (DIT), and Peilan Tung of German Academic Exchange Service (DAAD).

>Read more on the NSRRC website

Image: Grand opening, ribbon cutting ceremony.

PREM students outfitting and upgrading CHESS x-ray beamlines

CHESS is fortunate to have three graduate students visiting from Puerto Rico. Supported by the NSF-PREM CiE2M – the Center for Interfacial Electrochemistry of Energy Materials – a partnership of The University of Puerto Rico, Rio PiedrasCampus (UPRRP), Universidad Metropolitana (UMET) and Universidad del Turabo (UT), and CHESS. 

This group forms an educational and innovative collaborative materials research effort to bring together a diverse and talented scientific community with experience and expertise in electro-chemistry, solid-state and inorganic chemistry, and synchrotron-based techniques to character energy materials in operando conditions at CHESS.  
The students have become an integral part of the team building out and commissioning new X-ray beamlines at the upgraded CHESS facility. New to them was learning good ultra-high vacuum (UHV) practices, using tools like torque wrenches to set vacuum seals, and using an RGA to find chemical contamination in optics boxes (“was really interesting!”). They have also studied the design of beamline components in each sector: apertures, safety bricks and power filters required to deliver X-rays to experimental hutches.
Melissa’s favorite activity was assembling components for Sector 4 X-ray monochromator. “It is like a puzzle to solve. There are many different plates and bolts and it is a real challenge to assemble based on the 3D CADmodel. There is a correct order to do things. It was fun to install water cooled components in the vacuum chamber,” she says.

>Read more on the CHESS website

Image: Brenda, Joesene, Melissa, and Alan Pauling (right) of CHESS proudly display their ultra-high vacuum assembly and installation in the Sector 2 cave of the new CHESS beamline. The students have worked hand-in-hand with CHESS staff to assemble, test and prepare the X-ray beampipes in three different sectors of CHESS. 

Coelacanth reveals new insights into skull evolution

A team of researchers, in conjunction with the National Museum of Natural History in Paris, presents the first observations of the development of the skull and brain in the living coelacanth Latimeria chalumnae.

The study, published in Nature, uses data from beamline ID19 and provides new insights into the biology of this iconic animal and the evolution of the vertebrate skull.
The coelacanth Latimeria is a marine fish closely related to tetrapods, four-limbed vertebrates including amphibians, mammals and reptiles. Coelacanths were thought to have been extinct for 70 million years, until the accidental capture of a living specimen by a South African fisherman in 1938. Eighty years after its discovery, Latimeria remains of scientific interest for understanding the origin of tetrapods and the evolution of their closest fossil relatives – the lobe-finned fishes.

>Read more on the European Synchrotron website

Image: Overall anterolateral view of the skull of the coelacanth foetus imaged on beamline ID19. The brain is in yellow.
Credit: H. Dutel et al.

Real-time characterisation of a new miniature-honeycomb fuel cell

A team from Imperial College has designed a miniature ceramic solid oxide fuel cell with excellent properties and together with scientists from the University College London, the company Finden and the ESRF, they characterised the cell as it works on beamline ID15A, confirming the great performances of the new device.

Ceramic fuel cells are considered as one of the most promising technologies for sustainable energy generation thanks to their interesting features, such as higher efficiency compared to conventional combustion-based power plants, high operating temperatures (600 – 1000 °C) that generate high-grade waste heat, and superior fuel flexibility that allows the direct utilization of hydrocarbons.

To date, ceramic fuel cells are used in a wide range of applications, including stationary power supply, combined heat and power system (CHP), auxiliary power units (APU), etc., and will continue receiving attention as shale gas and biofuels are becoming the premium fuel choices thanks to their low carbon footprint.

>Read more on the European Synchrotron website

Image: Micro-computed tomography and X-ray diffraction computed tomography images. XRD-CT maps of LSM (green), YSZ (red) and NiO (blue) have been overlaid on top of a micro-CT image collected at the same z position. The scale bar corresponds to 0.5 mm.
Credit: Tao Li.

Exotic properties of iridium compounds

Scientists at DESY’s X-ray source PETRA III and the London Centre for Nanotechnology, at University College London, have developed a new method for examining the astonishing properties of a special class of iridium oxides known as iridates. The team of principal author Pavel Alexeev, from the Dynamics Beamline P01 at PETRA III, is presenting the procedure in the journal Scientific Reports.

Many oxides belonging to certain groups of transition metals (chemical elements with an incomplete d electron shell) are known for their exotic magnetic and electronic properties. These can be attributed qualitatively to a range of interactions between the charge of the electrons, their magnetic moment, their localization within the crystals and their atomic orbitals. The relative strengths of the various interactions determine whether an oxide is magnetic, an insulator, an electrical conductor or even a superconductor. The so-called 4d and 5d transitions metals are particularly interesting in this respect.

The properties of many of these oxides can be specifically adjusted by applying external electric or magnetic fields, or exerting pressure on the material. This makes them interesting for numerous applications in micro- and nanoelectronics, for data storage and information processing. Such behaviour is particularly pronounced in the oxides of 5d transition metals, such as tantalum, tungsten, osmium and iridium. The oxides of iridium are especially remarkable because they lose their magnetisation when subjected to pressure, and even under normal conditions develop unexpected magnetic structures. Although some of their properties have been known for quite a while, efforts to explain this behaviour are still in their infancy. This makes it all the more important to develop methods that provide detailed insights into such materials.

A particularly suitable and extremely sensitive method of studying the electronic and magnetic properties of solids is nuclear resonant scattering (NRS) using synchrotron radiation. This method uses the nuclei of the atoms of certain isotopes as local probes for the material’s properties. In view of its numerous possible applications, specialised measuring stations have been set up for this purpose on the P01 beamline at PETRA III, which are used by many scientists from all over the world every year. Among other things, the method allows the orientation of atomic magnetic moments to be determined with great accuracy. NRS therefore complements other X-ray techniques and – in contrast to neutron techniques – makes it possible to study small samples, for example when used on samples subject to high pressure.

>Read more on the PETRA III at DESY website

Image: Samples of strontium-iridium-trioxid crystals.
Credit: University College London, James Vale/Emily Hunter

Funding research crucial to Africa: Energy and healthcare

The 27th March 2019 saw the official launch of START (Synchrotron Techniques for African Research and Technology), a £3.7M grant awarded to a consortium of researchers led by Diamond Light Source by the Science and Technology Facilities Council (STFC) to work with African scientists on START.

Africa does not yet have a synchrotron light source, but African researchers are keen to apply synchrotron techniques to their research problems. The START project will fund research posts in Africa and the UK with a focus on two key areas crucial to development in Africa – energy and healthcare . The scientific results that come out of the project will be valuable in themselves, and may also lead to commercial applications, but START will also promote the development of research capabilities within Africa, and international research collaborations.

For Diamond Principal Investigator, Prof. Chris Nicklin, this will be the most important result: It is an exciting prospect to work together on these challenging problems and this funding will enable us to form very strong links at all levels, in particular helping to train the next generation of researchers in nations that have not had the chance to access and exploit synchrotron based techniques in their research. The work will focus around the development needs of African countries, driven by the Africa-based investigators and the non-government organisations (NGOs) that we have on board.

>Read more on the Diamond Light Source website

Low background noise crucial for single particle imaging experiments

Model experiment brings scientists a step closer to SPI at European XFEL

Taking snapshots of single molecules with X-rays has long been a dream for many scientists. Such experiments have successfully been computationally modelled, but have never been practically demonstrated before.
In a model experiment carried out at the European Synchrotron Radiation Facility (ESRF), European XFEL scientists, together with international collaborators, have now come one step closer to successfully carrying out so-called single particle imaging experiments (SPI) at X-ray laser facilities such as European XFEL. In a paper published today in the journal from the International Union of Crystallography (IUCrJ), scientists demonstrate experimentally that, in principle, a 3D structure can indeed be obtained from many tens of thousands of very weak images, using X-rays with similar properties as produced at X-ray free-electron lasers such as European XFEL.

>Read more on the European XFEL website

Image: Reconstruction of the 3D electron density. (a) Reconstruction from the result derived by EMC. The electron density projected along an axis perpendicular to the drawing plane is shown here. (b) Reconstruction from the reference Fourier volume. Again, the projected electron density is shown. (c) 3D iso-surface rendering of the reconstructed electron density shown in panel (a). The threshold of the iso-surface has been set to 0.2, given a normalized density with values between 0 and 1. (d) Scanning electron micrograph from the original sample.
Image source

Scientists develop printable water sensor

X-ray investigation reveals functioning of highly versatile copper-based compound

A new, versatile plastic-composite sensor can detect tiny amounts of water. The 3d printable material, developed by a Spanish-Israeli team of scientists, is cheap, flexible and non-toxic and changes its colour from purple to blue in wet conditions. The researchers lead by Pilar Amo-Ochoa from the Autonomous University of Madrid (UAM) used DESY’s X-ray light source PETRA III to understand the structural changes within the material that are triggered by water and lead to the observed colour change. The development opens the door to the generation of a family of new 3D printable functional materials, as the scientists write in the journal Advanced Functional Materials (early online view).

>Read more on the PETRA III at DESY website

Image: When dried, for example in a water-free solvent, the sensor material turns purple.
Credit: UAM, Verónica García Vegas

Watching molecules in a light-triggered catalyst ring ‘like an ensemble of bells’

A better understanding of these systems will aid in developing next-generation energy technologies.

Photocatalysts ­– materials that trigger chemical reactions when hit by light – are important in a number of natural and industrial processes, from producing hydrogen for fuel to enabling photosynthesis.
Now an international team has used an X-ray laser at the Department of Energy’s SLAC National Accelerator Laboratory to get an incredibly detailed look at what happens to the structure of a model photocatalyst when it absorbs light.
The researchers used extremely fast laser pulses to watch the structure change and see the molecules vibrating, ringing “like an ensemble of bells,” says lead author Kristoffer Haldrup, a senior scientist at Technical University of Denmark (DTU). This study paves the way for deeper investigation into these processes, which could help in the design of better catalysts for splitting water into hydrogen and oxygen for next-generation energy technologies.
“If we can understand such processes, then we can apply that understanding to developing molecular systems that do tricks like that with very high efficiency,” Haldrup says.

>Read more on the Linac Coherent Light Source at SLAC website

Image: When photocatalyst molecules absorb light, they start vibrating in a coordinated way, like an ensemble of bells. Capturing this response is a critical step towards understanding how to design molecules for the efficient transformation of light energy to high-value chemicals.
Credit: Gregory Stewart/SLAC National Accelerator Laboratory

Water is more homogeneous than expected

In order to explain the known anomalies in water, some researchers assume that water consists of a mixture of two phases even under ambient conditions.

However, new X-ray spectroscopic analyses at BESSY II, ESRF and Swiss Light Source show that this is not the case. At room temperature and normal pressure, the water molecules form a fluctuating network with an average of 1.74 ± 2.1% donor and acceptor hydrogen bridge bonds per molecule each, allowing tetrahedral coordination between close neighbours.
Water at ambient conditions is the matrix of life and chemistry and behaves anomalously in many of its properties. Since Wilhelm Conrad Röntgen, two distinct separate phases have been argued to coexist in liquid water, competing with the other view of a single-phase liquid in a fluctuating hydrogen bonding network – the continuous distribution model. Over time, X-ray spectroscopic methods have repeatedly been interpreted in support of Röntgen’s postulate.

>Read more on the BESSY II at HZB website

Image: Water molecules are excited with X-ray light (blue). From the emitted light (purple) information on H-bonds can be obtained.
Credit: T. Splettstoesser/HZB