A scientist’s life: At the edge of what is known

Quinn Carvalho is a PhD student at Oregon State University and a user at the Advanced Light Source (ALS) at Lawrence Berkeley National Lab in California. Quinn and his colleagues are using spectroscopic techniques to develop design strategies for electrocatalysts that will provide the resources we need for a carbon-free world. In his #LightSourceSelfie, Quinn shares what excites him about his research and his experiences on the support provided by beamline staff at the ALS. Reflecting on what drives him as a research scientist, Quinn explains, “That moment when you realise that you’re the first person to observe, measure and describe a physical phenomenon is one of the greatest sensations I’ve experienced as a professional and something that motivates me still to this day.”

Life in synchrotron radiation research

Including the day an earthquake interrupted my beam time!

Today’s #LightSourceSelfie is brought to you by Ro-Ya Liu, Assistant Research Scientist at NSRRC, operators of the Taiwan Light Source and the Taiwan Photon Source. Ro-Ya’s research area is focused on probing the electronic structure of novel materials by using angle resolved photoemission spectroscopy. She was inspired by her Master’s supervisor whose eyes shone as he presented his new data on the quantum well state of ultra-high silver thin film. Ro-Ya wanted to experience this spark and purpose in life. After a shaky first experiment (literally shaky due to an Earthquake!), Ro-Ya has done just that during a career that has already involved working at the Taiwan Light Source, the Photon Factory, Spring 8, HiSOR, Elettra, the Advanced Light Source and Diamond Light Source. Ro-Ya is still learning from colleagues including beamline engineers and users coming to conduct experiments at the Taiwan Light Source. Their deep knowledge helps Ro-Ya in her beamline manager role. She is looking to dig deep to acquire this knowledge and continue to find great purpose in her life in synchrotron radiation research.

Protecting our bones after diabetes and hypertension

On November 14, World Diabetes Day aims to raise awareness for the global health threat posed by diabetes, which affects over 460 million people globally, and to promote coordinated efforts to confront diabetes.

People living with type II diabetes and hypertension face an increased risk of bone fractures. An international team of researchers has used the Canadian Light Source (CLS) at the University of Saskatchewan (USask) to identify a potential bone health therapy that could one day alleviate that problem.

The collaboration between the Bone-Muscle Research Center at the University of Texas at Arlington (BMRC-UTA) and the Colleges of Medicine and Kinesiology at USask explored whether hepatocyte growth factor (HGF) could help reduce the fracture risk for people with type II diabetes. Since 50-85 % of diabetic patients live with hypertension, and both conditions are linked to a higher risk of breaks, this population is particularly vulnerable.

Dr. Kamal Awad, research scientist at the BMRC-UTA and first author on the study, said “bones protect our internal organs and allow us to move, thus maintaining a healthy bone is crucial especially for people suffering from diabetes and hypertension”.

This study focused on HGF, which is a naturally occurring molecule that is known to regulate cell growth throughout the body. Awad said it is also “associated with bone regeneration, remodelling, and the balance between osteoblast and osteoclast, but what was unknown is how HGF affects the chemical structure of the bone.”

Natasha Boyes, a PhD candidate specializing in cardiovascular disease in the College of Kinesiology at USask and first co-author, is interested in the whole-body effects of cardiovascular disease, and explained remodelling as a change process bones undergo throughout a person’s life.

“Most people think bone should be hard,” she said, “but hard bone can be very brittle. What you want is bone with the right architecture, and bone is always changing. Any stimulus can cause bone to adjust its structure. For example, if you’re a runner, your bones will change and adapt to better cope with the pounding (biomechanical stress). That’s remodelling.”

To explore how HGF might improve bone health, the researchers did site-specific injections of HGF on diabetic hypertensive rats, then used spectroscopy at the CLS to study the bone chemical structure with a focus on calcium and phosphorous. The team utilized the facility’s specialized SGMVLS-PGM, and SXRMB beamline facilities for this analysis.

Read more on the CLS website

Image: VLS-PGM beamline

Credit: CLS

Disorder brings out quantum physical talents

Quantum effects are most noticeable at extremely low temperatures, which limits their usefulness for technical applications. Thin films of MnSb2Te4, however, show new talents due to a small excess of manganese. Apparently, the resulting disorder provides spectacular properties: The material proves to be a topological insulator and is ferromagnetic up to comparatively high temperatures of 50 Kelvin, measurements at BESSY II show.  This makes this class of material suitable for quantum bits, but also for spintronics in general or applications in high-precision metrology.

Quantum effects such as the anomalous quantum Hall effect enable sensors of highest sensitivity, are the basis for spintronic components in future information technologies and also for qubits in quantum computers of the future. However, as a rule, the quantum effects relevant for this only show up clearly enough to make use of them at very low temperatures near absolute zero and in special material systems.

Read more on the HZB website

Image: The Dirac cone is typical for topological insulators and is practically unchanged on all 6 images (ARPES measurements at BESSY II). The blue arrow additionally shows the valence electrons in the volume. The synchrotron light probes both and can thus distinguish the Dirac cone at the surface (electrically conducting) from the three-dimensional volume (insulating).

Credit: © HZB

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

First light at Furka: The experiments can begin

It’s another milestone on the path to full operation of the X-ray free-electron laser SwissFEL with five experiment stations in all: “First light” at the experiment station Furka. It clears the way for experimental possibilities that are unique worldwide. Team leader Elia Razzoli explains what the Furka Group is planning to do.

Why is “first light” such an important occasion for your team?

Elia Razzoli: It means we’re in business. Or to be more specific: Now we can begin working on the first experiments.

The general public might imagine that you simply flip a switch, and then the light is there. But presumably it’s not that simple in your case . . .

No, it is a complex task. When we at SwissFEL talk about light, we do not mean visible light, but rather X-ray light with characteristics that are unique in the world. To generate that light, and for research to be able to use it, several teams at PSI have to work together. With the Furka experiment station we are, so to speak, at the end of the food chain. To generate the X-ray light of SwissFEL, electrons must be forced onto a sinuous track with the aid of magnets. In the process, they emit the X-ray light that we need to carry out the actual investigations. The magnets that redirect the electrons in this way are called undulators. And they are precisely what makes the whole thing so difficult, because they have to work exactly in sync; otherwise the X-ray light doesn’t have the quality that we need. The complexity of the system grows exponentially with the number and length of the undulators. That is why first light at Furka is already a masterful technical and organisational feat.

Read more on the PSI website

Image: Members of the team that achieved the milestone at the Furka station of SwissFEL: Eugenio Paris (left), Elia Razzoli, Cristian Svetina (right)

Credit: Paul Scherrer Institute/Mahir Dzambegovic

Scientists uncover a different facet of fuel-cell chemistry

Solid oxide fuel cells (SOFCs) are a promising technology for cleanly converting chemical energy to electrical energy. But their efficiency depends on the rate at which solids and gases interact at the devices’ electrode surfaces. Thus, to explore ways to improve SOFC efficiency, an international team led by researchers from Berkeley Lab studied a model electrode material in a new way—by exposing a different facet of its crystal structure to oxygen gas at operating pressures and temperatures.

“We began by asking questions like, could different reaction rates be achieved from the same material, just by changing which surface the oxygen reacts with?” said Lane Martin, a faculty scientist in Berkeley Lab’s Materials Sciences Division. “We wanted to examine how the atomic configuration at specific surfaces of these materials makes a difference when it comes to reacting with the oxygen gas.”

Thin films of a common SOFC cathode material, La0.8Sr0.2Co0.2Fe0.8O3 (LSCF), were epitaxially grown to expose a surface that was oriented along a diagonal crystallographic plane. Electrochemical measurements on this atypical surface yielded oxygen reaction rates up to three times faster than those measured on the usual horizontal plane.

To better understand the mechanisms underlying this improvement, the researchers used Advanced Light Source (ALS) Beamline 9.3.2 to perform ambient-pressure spectroscopy experiments at high temperatures and in varying pressures of oxygen. The results, combined with first-principles calculations, revealed that different crystallographic planes stabilize different surface chemistries, even though the bulk chemistry of the films is identical.

Read more on the ALS website

Image: A model SOFC cathode material adsorbs oxygen molecules (purple spheres) at vacancy sites, an important step in the electrochemical reaction taking place in fuel cells. Ambient-pressure experiments at the ALS allowed measurement of the surface chemical and electronic interactions at high temperature so that researchers could “see” the adsorption of oxygen at it happens. Light blue = La, dark blue = Sr, red = lattice O or O2 molecules, purple = adsorbed O2 molecules.

Credit: Abel Fernandez/UC Berkeley

Dublin researchers study phosphorus cycling and water quality

Using the Canadian Light Source at the University of Saskatchewan, Trinity College Dublin researchers have studied long term phosphorus storage and release in environmental systems, information which can help guide water quality management.

Phosphorus applied to agricultural crops is stored in various mineral and organic forms. This accumulated phosphorus is termed “legacy phosphorus” and can take decades to eventually mineralize and leach back into aquatic systems in a form living things can use.

“Phosphorus in lake and river systems is being recycled back into the water column degrading water quality through weed and algal growth cycles which can initially be exacerbated if phosphate inputs are stopped or significantly reduced” said Dr. David O’Connell, Assistant Professor of Contaminant Hydrology and Hydrogeology at Trinity College Dublin.

He recently published two papers with international collaborators that explore legacy phosphorus in river and lake systems, elucidating the processes and mechanisms through which phosphorus is stored and released in these systems over the long term.

Read more on the CLS website

Image: Flow measurements at the Bunuoke catchment.

Credit: Dr. David O’Connell

Titanium defective sites in TS-1: structural insights by combining spectroscopy and simulation

Titanium Silicalite-1 (TS-1) is a titanium zeolite, whose peculiarity is the presence of Ti atoms isomorphously substituting the Si ones at tetrahedral framework positions. However, real TS-1 samples are characterized by the co-presence of other Ti sites, ranging from extended TiO2phases down to defective Ti sites. The “defective Ti” label covers a broad range of possible Ti moieties, whose structural description is in most of the cases barely qualitative in the literature. In this work, we combined experimental and theoretical approaches, aiming to unravel the exact structure of defective Ti sites. 

Read more on the Elettra website

Laser, camera, action: Ultrafast ring opening of thiophenone tracked by time-resolved XUV photoelectron spectroscopy

Light-induced ring opening reactions form the basis of important biological processes such as vitamin D synthesis, and are also touted as promising candidates for the development of molecular switches. In recent years, new time-resolved techniques have emerged to investigate these processes with unprecedented temporal and spatial resolution.

An international research team from the USA, UK, Germany, Sweden, Australia, and the local team at the FERMI free-electron laser, combined time-resolved photoelectron spectroscopy with high-level electronic structure and molecular dynamics calculations to unravel the dynamics of a prototypical reaction along the full photochemical cycle of a ring molecule (thiophenone) – from photoexcitation, ring opening, all the way through to the subsequent ground state dynamics, and spanning a range of tens of femtoseconds  to hundreds of picoseconds. “These processes have intrigued the photochemistry community for decades” says Prof. Daniel Rolles from Kansas State University “and it is now routinely possible to visualize electronic changes and the movement of atoms in the molecule at each step of a chemical reaction”.

Read more on the ELETTRA website

Image: Artistic rendering of the photo-induced ring opening of thiophenone (left) into several open-ring products (right). The thin white lines show smoothed paths of actual trajectories. Illustration: KSU, Daniel Roles.

Transition-metal dichalcogenide NiTe2: an ambient-stable material for catalysis and nanoelectronics

Recently, transition-metal dichalcogenides hosting topological states have attracted considerable attention for their potential implications for catalysis and nanoelectronics. The investigation of their chemical reactivity and ambient stability of these materials is crucial in order to assess the suitability of technology transfer. With this aim, an international team of researchers from Italy, Russia, China, USA, India, and Taiwan has studied physicochemical properties of NiTe2 by means of several experimental techniques and density functional theory. Surface chemical reactivity and ambient stability were followed by x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) experiments at the BACH beamline, while the electronic band structure was probed by spin- and angle-resolved photoelectron spectroscopy (spin-ARPES) at the APE-LE beamline

Read more on the Elettra website

Image:  a) Ni-3p and b) Te-4d XPS core-level spectra collected from as-cleaved NiTe2 (black curves) and from the same surface exposed to 2·10L of CO (red curves), H2O (green curves) and O2 (blue curves). Adapted from “S. Nappini et al., Adv. Funct. Mater. 30, 2000915 (2020); DOI: 10.1002/adfm.202000915” with permission from Wiley (Copyright 2020) with license 4873681106527

Determination of interatomic coupling between two-dimensional crystals

Following the isolation of graphene, many other atomically thin two-dimensional crystals have been produced and can even be stacked on top of each other in a desired order to form so called van der Waals heterostructures.

Subtle changes in the stacking, especially the angle between the crystallographic axes of two adjacent layers, can have big impact on the properties of the whole heterostructure. We use angle-resolved photoemission spectroscopy measurements carried out at the Spectromicroscopy beamline at Elettra to obtain interatomic coupling for carbon atoms by studying a three-layer stack of graphene. The coupling between atoms in two two-dimensional crystals, knowledge of which is necessary to describe the properties of the stack, can be determined by studying a structure made of three layers with two similar interfaces but one with crystallographic axes aligned and one twisted. This is because each of the interfaces provides complementary information and together they enable self-consistent determination of the coupling.

Read more on the Elettra website

Image: Angle resolved photoemission spectrum revealing the electronic bands of a microscopic three layer device having aligned and twisted graphene-graphene interfaces. Measurable band gaps are used to self-consistently determine fundamental parameters of interatomic coupling.

Human waste could help combat global food insecurity

Researchers from Cornell University’s College of Agriculture and Life Sciences and the Canadian Light Source (CLS) at the University of Saskatchewan have proven it is possible to create nitrogen-rich fertilizer by combining the solid and liquid components of human waste. The discovery, published recently in the journal Sustainable Chemistry and Engineering, has the potential to increase agriculture yields in developing countries and reduce contamination of groundwater caused by nitrogen runoff. 

Special separating toilets that were developed through the Reinvent the Toilet Challenge have helped solve long-standing sanitation problems in the slums of Nairobi, Kenya. However, the methods used to dispose of the two outputs failed to capture a key nutrient that local fields were starving for: nitrogen.

Cornell researchers Leilah Krounbi, a former PhD student, now at the Weizmann Institute in Israel, and Johannes Lehmann, senior author and professor of soil and crop sciences, wondered whether it might be possible to close the waste stream loop by recycling nitrogen from the urine, which was otherwise being lost to runoff.  While other researchers have engineered adsorbers using high-tech ingredients such as carbon nanotubes or activated carbons, Lehmann and his team wanted to know if they could do so with decidedly low-tech materials like human feces. Adsorbers are materials whose surfaces can capture and hold gas or liquids.

Read more on the Canadian Light Source website

Image: The researchers used the SGM beamline at the CLS to see how the chemistry in the nitrogen changed as it adsorbed ammonia and how well their material could make nitrogen available to plants if it was used as a fertilizer.  

A closer look at superconductors

A new measuring method helps understand the physics of high-temperature superconductivity

From sustainable energy to quantum computers: high-temperature superconductors have the potential to revolutionize today’s technologies. Despite intensive research, however, we still lack the necessary basic understanding to develop these complex materials for widespread application. “Higgs spectroscopy” could bring about a watershed as it reveals the dynamics of paired electrons in superconductors. An international research consortium centered around the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and the Max Planck Institute for Solid State Research (MPI-FKF) is now presenting the new measuring method in the journal Nature Communications (DOI: 10.1038/s41467-020-15613-1). Remarkably, the dynamics also reveal typical precursors of superconductivity even above the critical temperature at which the materials investigated attain superconductivity.

Read more on the TELBE at HZDR website

Image: Deciphering previously invisible dynamics in superconductors – Higgs spectroscopy could make this possible: Using cuprates, a high-temperature superconductor, as an example, an international team of researchers has been able to demonstrate the potential of the new measurement method. By applying a strong terahertz pulse (frequency ω), they stimulated and continuously maintained Higgs oscillations in the material (2ω). Driving the system resonant to the Eigenfrequency of the Higgs oscillations in turn leads to the generation of characteristic terahertz light with tripled frequency (3ω).

Significant progress on ultraflexible solar cells

Research from Monash University, the University of Tokyo and RIKEN, partly undertaken at the Australian Synchrotron, has produced an ultra-flexible ultra-thin organic solar cell that delivered a world-leading performance under significant stretching and strain.

The development paves the way forward for a new class of stretchable and bendable solar cells in wearable devices, such as fitness and health trackers, and smart watches with complex curved surfaces.

The advance, which was published in Joule, was made possible by designing an ultra-thin material based on a blend of polymer, fullerene and non-fullerene molecules with the desired mechanical properties and power efficiency, according to Dr Wenchao Huang, a Research Fellow at Monash University and the article’s first author.
The thickness of the solar cell film is only three micrometres, which is ten times smaller than the width of a human hair.

Dr Huang, who completed his PhD in the lab of Prof Chris McNeill at Monash on flexible organic solar cells, received the Australian Synchrotron’s Stephen Wilkins Medal in 2016 for his exceptional doctoral thesis that made use of the synchrotron-based research capabilities at the facility.

>Read more no the Autralian Lightsource at ANSTO website

Image: Schematic of ultraflexible solar cell

Beyond graphene: monolayer arsenene observed for the first time

An article recently published in 2D Materials shows the first experimental evidence of the successful formation of arsenene, an analogue of graphene with noteworthy semiconducting properties.

This material shows a great potential for the development of new nanoelectronics. Crucial sample preparation and electron spectroscopy experiments were performed at the Bloch beamline at MAX IV.

The discovery of graphene, the single-layer carbon honeycomb material worth the Nobel Prize in Physics in 2010, surely has had a revolutionary impact on research. It triggered a whole new field of study within two-dimensional (2D) materials. However, its application in developing new 2D electronics has been hindered by its lack on an intrinsic band gap. Researchers therefore started to turn their attention to other elements in the periodic table and set their eyes on group V, to which arsenic belongs.
“The aim of the study was to show that arsenene can be formed. Our article is the first to report this”, says Roger Uhrberg, professor at Linköping University and spokesperson for the Bloch beamline at MAX IV. Arsenene, a single-layer buckled honeycomb structure of arsenic, had been previously predicted by various theoretical studies, but this is the first experimental observation that verifies its existence.

>Read more on the MAX IV website

Image: A view of the Bloch beamline at MAX IV. The Bloch beamline consists of two branchlines, and is dedicated to high resolution photoelectron spectroscopy, encompassing angle-resolved (ARPES), spin resolved (spin-ARPES) and core-level spectroscopy.