Natural substances show promise against coronavirus

X-ray screening identifies compounds blocking a major corona enzyme

Three natural compounds present in foods like green tea, olive oil and red wine are promising candidates for the development of drugs against the coronavirus. In a comprehensive screening of a large library of natural substances at DESY’s X-ray source PETRA III the compounds bound to a central enzyme vital for the replication of the coronavirus. All three compounds are already used as active substances in existing drugs, as the team headed by Christian Betzel from the University of Hamburg and Alke Meents from DESY reports in the journal Communications Biology. However, if and when a corona drug can be developed on the basis of these compounds remains to be investigated.

“We tested 500 substances from the Karachi Library of Natural Compounds if they bind to the papain-like protease of the novel coronavirus, which is one of the main targets for an antiviral drug,” explains the study’s main author Vasundara Srinivasan from the University of Hamburg. “A compound that binds to the enzyme at the right place can stop it from working.”

The papain-like protease (PLpro) is a vital enzyme for virus replication: When a cell is hijacked by the coronavirus, it is forced to produce building blocks for new virus particles. These proteins are manufactured as a long string. PLpro then acts like a molecular pair of scissors, cutting the proteins from the string. If this process is blocked, the proteins cannot assemble new virus particles.

Read more on the DESY website

Image: The paper’s main author Vasundara Srinivasan at an X-ray set-up to test protein crystals in the lab.

Credit: University of Hamburg, Susanna Gevorgyan

Weird fossil is not our ancestor

It has recently been supposed that humans could trace their ancestry back to a strange microscopic creature with a mouth and no anus. Thanks to analysis of 500 million year old fossils at the Swiss Light Source SLS, we can be relieved to find out this is not true: Saccorhytus is not a deuterostome like us, but an ecdysozoan. The findings, published today in Nature, make important amendments to the early phylogenetic tree and our understanding of how life developed.

In 535 million year old rocks in China is a mysterious microfossil whose evolutionary affinity is hotly debated. Saccorhytus was originally described in 2017 as an ancestral deuterostome, a member of the group from which our own deep ancestors emerged. It is microscopic in size – about a millimetre in diameter – and resembles a spikey, wrinkly sack, with a mouth surrounded by spines and holes that were interpreted as pores for gills – a primitive feature of the group. This made for a very unexpected origin of deuterostomes: within sand-grain sized organisms that may have lived among the sand or floating in the sea. However, the evidence supporting this view was always very weak – were those holes around the mouth really gill pores?

The researchers tried to address this question by collecting new specimens of Saccorhytus, dissolving tonnes of rock with strong vinegar and picking through the resulting grains of sand for these rare fossils. The fossils are no longer rare – the teams recovered hundreds of specimens, many much better preserved than any seen before, providing new insights into the anatomy and evolutionary affinity of Saccorhytus.

“Some of the fossils are so perfectly preserved that they look almost alive,” says Yunhuan Liu, professor in Palaeobiology at Chang’an University, Xi’an, China. “Saccorhytus was a curious beast, with a mouth but no anus, and rings of complex spines around its mouth.”

Read more on the PSI website

Image: The reconstructions show the fossil of Saccorhytus from the front

Credit: Graphic: Dinghua Yang

Benedetta Casu’s #My1stLight

Synchrotron: Destiny


When I was a physics student, the Physics Department of my University in the capital city of Sardinia organized a journey to Berlin for the senior master students to visit the most important labs. Among them, there was BESSY I. What an incredible experience, everything looked so fantastic, exciting, and complicated.


After that, for sake of curiosity, I attended the Italian synchrotron School that at the time was organized in Sardinia. I attended the school because I wanted to know more about synchrotron light, but I was sure that it would stay a “cultural opportunity” and nothing more.


A few years later I was offered a Ph.D. position at the University of Potsdam. The plan was that I would have been in charge of photocurrent investigations. BUT, the Ph.D. student that was in charge of the beamtime at Synchrotron in the same research group was never back from his vacation preferring to stay in sunny Spain. My supervisor decided that I would take over the Synchrotron beamtimes.


My very first beamtime was with the last photon at BESSY I.

Since then, I had the opportunity to perform wonderful experiments using Synchrotron facilities all over Europe, from working with the world record laterally resolved PEEM-LEEM at BESSY II to measuring XMCD at 150 mK at Petra III. I am also one of the German national delegates of the European Synchrotron and FEL User Organisation (ESUO).


Synchrotron was certainly my destiny

Image: Benedetta Casu during beamtime at BESSY II

Credit: Benedetta Casu

Gene therapy proved against muscular dystrophy with the ALBA synchrotron

A study by the Sant Joan de Déu Research Institute, ICFO, CIBERER and the ALBA Synchrotron has helped demonstrate that gene therapy can reverse the effects of the mutation that causes the symptoms of congenital muscular dystrophy in patient cells. The mutation, which leads to a disorder in the body’s collagen, has been silenced through a genetic editing technique based on the CRISPR/Cas9 system. Experiments at the MISTRAL beamline in ALBA have revealed previously unknown cell damage. Congenital muscular dystrophy is a rare minority disease that mainly affects children and has no treatment.

Congenital muscular dystrophy is a group of rare neuromuscular diseases. In particular, type VI collagen deficiency-related dystrophy affects less than 1 in 100,000 people, has varying degrees of severity, and has no cure.

Read more on the ALBA website

Image: Three-dimensional reconstruction of whole-cell volumes of control- (“healthy cell”), and patient-derived fibroblasts and CRISPR-treated fibroblasts. The different organelles present in the cells can be seen: nucleus in yellow, mitochondria in light blue, endo/lysosomal-like vesicles in violet, and multivesicular bodies in pink.

Green hydrogen: Nanostructured nickel silicide shines as a catalyst

Electrical energy from wind or sun can be stored as chemical energy in hydrogen, an excellent fuel and energy carrier. The prerequisite for this, however, is efficient electrolysis of water with inexpensive catalysts. For the oxygen evolution reaction at the anode, nanostructured nickel silicide now promises a significant increase in efficiency. This was demonstrated by a group from the HZB, Technical University of Berlin and the Freie Universität Berlin as part of the CatLab research platform with measurements among others at BESSY II.

Electrolysis might be a familiar concept from chemistry lessons in school: Two electrodes are immersed in water and put under voltage. This voltage causes water molecules to break down into their components, and gas bubbles rise at the electrodes: Oxygen gas forms at the anode, while hydrogen bubbles form at the cathode. Electrolysis could produce hydrogen in a CO2-neutral way – as long as the required electricity is generated by fossil free energy forms such as sun or wind.

The only problem is that these reactions are not very efficient and extremely slow. To speed up the reactions, catalysts are used, based on precious and rare metals such as platinum, ruthenium or iridium. For large-scale use, however, such catalysts must consist of widely available and very cheap elements.

Read more on the HZB website

Image: Crystalline nickel silicide (left) is chemically transformed into nanostructured material with excellent catalytic properties for the electrolytic splitting of water and the production of valuable nitrile compounds. 

Credit: © P. Menezes /HZB/TU Berlin

Enigmatic Dirac fermions in graphene

Since the discovery of graphene more than 15 years ago, research on graphene-based systems has grown exponentially. Graphene exhibits unique physical properties, for instance, the presence of massless Dirac fermions in a lattice of stronger covalent bonds and frequency-independent optical conductivity, which may help to realize exotic fundamental science and advanced technologies.

So far, graphene has been grown on a multitude of substrates exhibiting interesting properties. In some cases, the graphene layer has minimal link with the substrate. Experiments have revealed enigmatic properties of the Dirac fermions near the band crossing, called Dirac point, at the K point of the Brillouin zone. For example, Angle-Resolved PhotoEmission Spectroscopy (ARPES) data of graphene grown on SiC, shown in Fig. 1a, exhibit large momentum independent intensities near Dirac point as if the top and bottom of the Dirac cone are shifted away from each other. Some studies interpreted these results as a gapped Dirac cone with anomalous in-gap intensities as schematically shown in Fig. 1b. The presence of electron correlation renormalizes the dispersion as shown by red lines. Other proposals involve plasmaron bands where plasmon excitations in addition to photoexcitation of electrons leads to a shifted Dirac cone. The shifted and the pristine Dirac cones appear as a diamond shaped structure around the Dirac point as shown in Fig. 1c.

In order to address this enigmatic scenario, A. Pramanik, S. Thakur and colleagues from India, Italy and Germany performed a detailed polarization dependent ARPES investigation at the BaDElPh beamline at Elettra. Each branch of the Dirac cone was probed selectively using s– and p-polarized synchrotron light. The spectra shown in Fig. 2a,b reveal clearly dispersive bands near the Dirac point.

Read more on the Elettra website

Image: (a) Typical ARPES spectra of graphene on SiC along the ΓKM direction of the Brillouin zone; the origin of the momentum axis is shifted to K point. Schematic of (b) anomalous region and (c) plasmaron scenario around the Dirac point. Red curved lines in (b) show bands in the presence of electron correlation. Red Dirac cone in (c) is due to plasmaron bands.

Understanding how motor proteins shape our cells

Understanding the busy networks inside our cells can help researchers develop new cancer treatments and prevent dangerous fungal infections.

With the help of the Canadian Light Source (CLS) at the University of Saskatchewan, a research team led by John Allingham from Queen’s University and Hernando Sosa from the Albert Einstein College of Medicine has shed light on a protein that regulates the intricate microscopic networks that give cells their shape and helps ship important molecules to diverse locations.

Using the CMCF beamline at the CLS and the cryo-EM facility at the Simons Electron Microscopy Center (SEMC) at the New York Structural Biology Center, the team found the missing pieces of an important puzzle.

In their published work, they are the first group to clearly describe the mechanism of action of a tiny motor protein called Kinesin-8 that enables it to control the structures of microtubule fiber networks inside the cell.

Read more on the CLS website

Image: Cells, Canadian Light Source.

Targeting a parasite’s DNA could be more effective way to treat malaria

Research from the University of Sheffield using Diamond has explored a new way of killing the Plasmodium parasite that causes malaria. 

According to the World Health Organisation, there were 241 million cases of malaria and 627,000 deaths worldwide in 2020 – making the study and treatment of this disease a high-priority issue for scientists around the world. In a feasibility study, researchers from the University of Sheffield used Diamond to reveal a novel way of fighting the life-threatening disease, malaria. The study discovered molecules that interfered with the parasite’s DNA processing enzyme, but not the equivalent human one. 

A research team from the University of Sheffield’s Department of Infection, Immunity and Cardiovascular Disease examined and targeted an enzyme that maintains the classic double-helical structure of the malaria parasite’s DNA, which contains the blueprint of life, which could be a more effective way to combat malaria.

Read more on the Diamond website

Image: A flap endonuclease cuts DNA (the orange intertwined worms), credit University of Sheffield

X-rays allow us to quickly develop high-strength steels

Knowing how strong a piece of steel is, especially the stainless steel used in everything from cars to buildings, is vitally important for the people who make and use it. This information helps to keep people safe during crashes and to prevent buildings from collapsing.

Accurately predicting the strength of a steel prototype based on its microstructure and composition would be indispensable when designing new types of steel, but it has been nearly impossible to achieve — until now.

“Designing/making the best-strength steel is the hardest task,” said Dr Harishchandra Singh, an adjunct professor at NANOMO and the Centre for Advanced Steels Research at the University of Oulu in Finland.

Estimating the contribution of various factors towards designing high-strength novel steel has traditionally required numerous tests that can take months, according to Singh. Each test also requires a new sample of the prototype. 

Read more on the CLS website

Image: Dr Harishchandra Singh, an adjunct professor at NANOMO and the Centre for Advanced Steels Research at the University of Oulu in Finland. He is standing next to steel components in the spectroscopy lab at NANOMO.

Dr. Chia-Hung Hsu Assumes Position as NSRRC Director

Dr. Chia-Hung Hsu officially assumes the position as the NSRRC Director on August 1, 2022, for a four-year term. Chairman Minn-Tsong Lin of the NSRRC Board of Trustees (BOT) presided over the directorship handover ceremony between the outgoing Director Gwo-Huei Luo and incoming Director Hsu. The BOT started searching and selecting a new director from January, 2022. Dr. Hsu earned a unanimous decision from the BOT for her wealth of experiences in management and exemplary accomplishments in science.

Director Hsu received her PhD degree in physics from Boston University, and possesses expertise in surface science and thin film X-ray scattering. After completing her postdoctoral research at Harvard University in 1993, she joined the NSRRC and took an active role in building the first X-ray beamline in Taiwan and Taiwan beamlines at SPring-8, Japan. Beside conducting scientific research and developing experimental techniques, she also teaches at National Yang Ming Chiao Tung University and National Tsing Hua University. She is highly experienced in administrative management through her previous roles as Head of Scientific Research Division, Chief Secretary, and BOT Executive Secretary at NSRRC, as well as a review panel member for physics at the National Science Council, and a council member of the Physical Society of Taiwan.

“NSRRC’s mission is to develop advanced light source technologies and to operate a science user facility that are both excellent and accessible,” said Chairman Lin. “After decades of efforts, NSRRC has empowered the nation through fruitful scientific results from fundamental, innovative and industrial research.”

Read more on the NSRRC website

Image: Dr. Chia-Hung Hsu Assumes Position as NSRRC Director

Aleksei Kotlov’s #My1stLight

Aleksei was responsible for setting up the new P66 beamline at PETRA III at DESY

Setting up the P66 beamline was a challenging time. The years of discussions, iterations, doubts, calculations, ordering of parts, and construction end at some point with commissioning of the beamline. Only then could you see the final result of your work and see that all decisions were right. To me personally it was like the birth of a baby. Suddenly you realize, that small beam spot on the sample is a big event for you and whole beamline community and to make it happen you have invested a significant part of your life.

Image: Aleksei on the P66 beamline at PETRA III

Canadian Light Source’s #My1stLight on the Far Infrared Beamline in 2005

The Queen of England helped us get the beamline operating in May of 2005, while she was visiting Saskatchewan and the Canadian Light Source with Prince Philip. The ring had been operating but the IR beamlines needed vacuum bellows installed due to delays in shipment. These would complete the UHV chambers to the window outside the shield wall. There were no beam outages on the schedule long enough to do this for 6 months into the fall, so the IR operation was being badly delayed.

But! the CLS had to shut down for a day before the Royal visit on Friday May 20*, to allow security screening and preparation for the Royals. So with two days of no-beam, the technicians quickly vented the ring magnet cell and installed the bellows and we had nearly 48 hours to pump down and bake the system. Then on Sat May 21 at 12:30 pm there was beam in the ring (thankfully no leaks from the bellows!) and the search for beam began. The M2 mirror was steered until a spot of light was seen glowing near the edge of the UHV window. This glow was adjusted to line up along one side, and a lateral scan was made while recording a video at the window.

At the controls was Dr. Dominique Appadoo, now at the Australian Synchrotron, who was the Far IR beamline scientist at the time. Assisting were Tim May the optics designer/project manager for the IR beamlines, and Craig Hyett a graduate student working on the IR beamlines. Subsequently the first light was steered out of the window port on the Mid IR beamline.

Image: Tim and Dominique searching for first light

* Read more on the CLS website

High pressure synthesis in gallium sulphide chalcogenide

Researchers from Universitat Politècnica de València, Universidad de La Laguna, Universidad de Cantabria and the ALBA Synchrotron have published a new work on high pressure chemistry in gallium (III) sulphide chalcogenide. In this work, relevant fingerprints (vibrational and structural) of a pressure-induced paralectric to ferroelectric phase transition are shown. This is the first time when a tetradymite-like (R3m) phase has been synthesized and observed experimentally in gallium-based sequichalcogenides. High pressure X-ray diffraction measurements were carried out at MSPD beamline of ALBA.

Gallium (III) sulphide (Ga2S3) is a compound of sulphur and gallium, that is a semiconductor that has a wide variety of applications in electronics and photonics: nano optoelectronics, photonic chips, electro-catalysis, energy conversion and storage, solar energy devices, gas sensors, laser-radiation detection, second harmonic generation, phase change memories or photocatalytic water splitting systems.

In this work published in Chemistry of Materials,scientists have shown relevant vibrational and structural fingerprints of a pressure-induced paraelectric to ferroelectric R-3m-to-R3m (β’-to-φ) phase transition under decompression on Ga2S3 chalcogenide.

This transition was theoretically predicted in several III−VI B2X3 compounds at high temperature (where B can be aluminium, gallium or indium and X, sulphur, selenium or tellurium). The novelty of this research stems from the synthesis of both phases: β-(R-3m) and α-In2Se3 (R3m)-like structures on Ga2S3 and tuning them via decreasing pressure. Within the III−VI B2X3 compounds, this R-3m-to-R3m (β’-to-φ-Ga2S3) phase transition had been observed experimentally only in the indium (III) selenide (In2Se3)compound, under varying temperature or pressure, to date.

This finding leads the way for designing cheap, nontoxic, nonrare-earth, and abundant element-based devices for second harmonic generation, photocatalytic splitting, ferroelectric, pyroelectric, and piezoelectric applications based on Ga2S3.

Read more on the ALBA website

Image: Samuel Gallego and Catalin Popescu at the MSPD beamline of ALBA.

A new leap in understanding nickel oxide superconductors

Researchers discover they contain a phase of quantum matter, known as charge density waves, that’s common in other unconventional superconductors. In other ways, though, they’re surprisingly unique.

BY GLENNDA CHUI

A new study shows that nickel oxide superconductors, which conduct electricity with no loss at higher temperatures than conventional superconductors do, contain a type of quantum matter called charge density waves, or CDWs, that can accompany superconductivity.

The presence of CDWs shows that these recently discovered materials, also known as nickelates, are capable of forming correlated states – “electron soups” that can host a variety of quantum phases, including superconductivity, researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University reported in Nature Physics today.

“Unlike in any other superconductor we know about, CDWs appear even before we dope the material by replacing some atoms with others to change the number of electrons that are free to move around,” said Wei-Sheng Lee, a SLAC lead scientist and  investigator with the Stanford Institute for Materials and Energy Science (SIMES) who led the study.

“This makes the nickelates a very interesting new system – a new playground for studying unconventional superconductors.”

Nickelates and cuprates

In the 35 years since the first unconventional “high-temperature” superconductors were discovered, researchers have been racing to find one that could carry electricity with no loss at close to room temperature. This would be a revolutionary development, allowing things like perfectly efficient power lines, maglev trains and a host of other futuristic, energy-saving technologies.

But while a vigorous global research effort has pinned down many aspects of their nature and behavior, people still don’t know exactly how these materials become superconducting.

So the discovery of nickelate’s superconducting powers by SIMES investigators three years ago was exciting because it gave scientists a fresh perspective on the problem. 

Since then, SIMES researchers have explored the nickelates’ electronic structure – basically the way their electrons behave – and magnetic behavior. These studies turned up important similarities and subtle differences between nickelates and the copper oxides or cuprates – the first high-temperature superconductors ever discovered and still the world record holders for high-temperature operation at everyday pressures.

Since nickel and copper sit right next to each other on the periodic table of the elements, scientists were not surprised to see a kinship there, and in fact had suspected that nickelates might make good superconductors. But it turned out to be extraordinarily difficult to construct materials with just the right characteristics.

“This is still very new,” Lee said. “People are still struggling to synthesize thin films of these materials and understand how different conditions can affect the underlying microscopic mechanisms related to superconductivity.”

Read more on the SLAC website

Image: An illustration shows a type of quantum matter called charge density waves, or CDWs, superimposed on the atomic structure of a nickel oxide superconductor. (Bottom) The nickel oxide material, with nickel atoms in orange and oxygen atoms in red. (Top left) CDWs appear as a pattern of frozen electron ripples, with a higher density of electrons in the peaks of the ripples and a lower density of electrons in the troughs. (Top right) This area depicts another quantum state, superconductivity, which can also emerge in the nickel oxide. The presence of CDWs shows that nickel oxides are capable of forming correlated states – “electron soups” that can host a variety of quantum phases, including superconductivity.

Credit: Greg Stewart/SLAC National Accelerator Laboratory

#SynchroLightAt75 – Operation of the PAL-XFEL in 2020

After the PAL-XFEL was opened to the public in 2017, beamtime for user service has increased every year to provide more opportunities for user experiments. In 2020, 2,819 hours were provided for user beamtime out of the planned 2,910 hours and the beam availability was 96.9%. The provided beamtime of 2,819 hours was a significant increase from 2,409 hours in 2019, as shown in Table 1. To further increase beamtime, the PAL-XFEL has plans for 24-hour operation and simultaneous operation of hard and soft X-ray beamlines in the near future.

YearPlanned BeamtimeProvided BeamtimeAvailability
20182,012 h1,921 h95.5%
20192,503 h2,409 h96.2%
20202,910 h2,819 h96.9%
Table 1. Planned and provided beamtime in 2018, 2019, and 2020

FEL saturation of 0.062 nm (20 keV) was achieved for the first time in PAL-XFEL. The measured FEL energy using the e-loss scan was 408 uJ, the FEL radiation spectrum was 25.3 eV rms (0.127% of the center photon energy), and the FEL pulse duration (FWHM) was 11 fs, which corresponds to 1×1011 photons/pulse. The e-beam energy was 10.4 GeV and the undulator K was 1.4. The undulator gap scan was conducted for 20 undulators to check the FEL saturation as shown in Figure 1. Here, quadratic undulator tapering is applied for the last 6 undulators and the calculated gain length was 3.43 m.

Figure 1. Measurement results of the saturation curve at 20 keV photon energy

Two-color FEL generation with a single electron bunch has been successfully demonstrated for the hard X-ray undulator line, broadening the research capabilities at the PAL-XFEL. Test experiments have been conducted at two photon energies, 9.7 keV and 12.7 keV. A pump pulse is generated with 8 upstream undulators of the self-seeding section and a probe pulse is generated with 12 downstream undulators of the self-seeding section. The photon energies of the pulses can be independently controlled by changing the undulator parameter K and the time delay between two pulses can be controlled from 0 to 120 femtoseconds by using the magnetic chicane installed at the self-seeding section.

Figure 2. Intensity measurement results of two-color FEL generations.

Ultra-bright hard x-ray pulses using the self-seeded FEL were applied to the demonstration of serial femtosecond crystallography (SFX) experiments in 2020. We have consistently improved the spectral purity and peak of the self-seeded FEL using a laser heater and optimized crystal conditions over a hard x-ray range from 3.5 keV to 14.6 keV. The peak brightness for self-seeded hard x-ray pulses was enhanced to almost ten times greater than that of the SASE FEL over hard x-ray ranges. For example, the peak brightness of an x-ray at 9.7 keV is 3.2×1035 photons/(s·mm2·mrad2·0.1%BW), which is the highest peak brightness ever achieved for free-electron laser pulses. Thanks to the ultra-bright x-ray pulse with narrow bandwidth and superior spectral purity, SFX experiment results using the seeded FEL showed better data quality with high resolutions compared with that using the SASE FEL. This work has been published in Nature Photonics (https://doi.org/10.1038/s41566-021-00777-z).

Figure 3. Comparison of measured FEL intensity between SASE and self-seeding FEL.

Buckyballs on gold are less exotic than graphene

C60 molecules on a gold substrate appear more complex than their graphene counterparts, but have much more ordinary electronic properties. This is now shown by measurements with ARPES at BESSY II and detailed calculations.

Graphene consists of carbon atoms that crosslink in a plane to form a flat honeycomb structure. In addition to surprisingly high mechanical stability, the material has exciting electronic properties: The electrons behave like massless particles, which can be clearly demonstrated in spectrometric experiments. Measurements reveal a linear dependence of energy on momentum, namely the so-called Dirac cones – two lines that cross without a band gap – i.e. an energy difference between electrons in the conduction band and those in the valence bands.

Variants in graphene architecture

Artificial variants of graphene architecture are a hot topic in materials research right now. Instead of carbon atoms, quantum dots of silicon have been placed, ultracold atoms have been trapped in the honeycomb lattice with strong laser fields, or carbon monoxide molecules have been pushed into place on a copper surface piece by piece with a scanning tunneling microscope, where they could impart the characteristic graphene properties to the electrons of the copper. 

Artificial graphene with buckyballs?

A recent study suggested that it is infinitely easier to make artificial graphene using C60 molecules called buckyballs. Only a uniform layer of these needs to be vapor-deposited onto gold for the gold electrons to take on the special graphene properties. Measurements of photoemission spectra appeared to show a kind of Dirac cone.

Analysis of band structures at BESSY II

“That would be really quite amazing,” says Dr. Andrei Varykhalov, of HZB, who heads a photoemission and scanning tunneling microscopy group. “Because the C60 molecule is absolutely nonpolar, it was hard for us to imagine how such molecules would exert a strong influence on the electrons in the gold.” So Varykhalov and his team launched a series of measurements to test this hypothesis.

In tricky and detailed analyses, the Berlin team was able to study C60 layers on gold over a much larger energy range and for different measurement parameters. They used angle-resolved ARPES spectroscopy at BESSY II, which enables particularly precise measurements, and also analysed electron spin for some measurements.

Read more on the HZB website

Image: Using density functional theory and measurement data from spin-resolved photoemission, the team investigated the origin of the repeating Au(111) bands and resolved them as deep surface resonances. These resonances lead to an onion-like Fermi surface of Au(111).

Credit: © HZB