SOLARIS – Page 3 – Lightsources.org

Relationship between enhanced electrochemical performance and partially amorphous material structure

2024/07/262024/07/29

A research team under the leadership of Sebastian Molin D.Sc., from the Faculty of Electronics, Telecommunications and Informatics at Gdańsk University of Technology (as part of a joint project with scientists from the Warsaw University of Technology and Kaunas University of Technology), in collaboration with ASTRA beamline scientists, characterised the perovskite oxide La_0.6Sr_)0.4CoO_3-δ as an oxygen electrode for solid oxide fuel cell technology. This material showed enhanced electrochemical efficiency for the reduction of oxygen when present in a partially amorphous form. Using X-ray absorption spectroscopy (XAS) at the SOLARIS synchrotron. The results of the study have been published in the journal of Applied Surface Science, published by Elsevier.

Image: Wavelet Transform calculated from EXAFS for La_0.6Sr_0.4CoO_3-δannealed at range 400 °C–700 °C.

Electronic Marvel of Tin

2024/07/182024/07/18

An international team of scientists has investigated the topological properties of grey tin (α-Sn), a low-temperature form of tin. They have successfully stabilized this form at room temperature by applying small compressive forces. Through a combination of complementary experimental techniques, the researchers demonstrated that α-Sn belongs to the class of Dirac topological semimetals and, under the influence of an external magnetic field, transforms into a Weyl semimetal phase. A significant part of the experiments exploring the fascinating electronic properties of this material was conducted at the URANOS beamline of the SOLARIS National Synchrotron Radiation Centre.

Tin, a seemingly ordinary and well-known material, reveals unique electronic properties under extreme conditions. Historically, α-Sn caused problems during harsh winters by destroying organ pipes in churches. However, this form now shows fascinating electronic properties. Scientists from the International Research Centre MagTop at the Institute of Physics of the Polish Academy of Sciences have stabilized and strained grey tin at room temperature on insulating substrates. The unusual electronic structure of α-Sn has been experimentally visualized using angle-resolved photoemission spectroscopy at the URANOS beamline at the SOLARIS Synchrotron Centre. The electron energy spectrum of α-Sn resembles a Dirac spectrum, typically observed in particles accelerated to speeds close to the speed of light. This discovery was further supported by magneto-optical experiments and theoretical calculations conducted by researchers from Johannes Kepler Universität in Linz and Ecole Normale Supérieure in Paris. Electrical transport measurements at the MagTop center revealed that applying a magnetic field parallel to the electrical current results in an unusual drop in resistance, manifesting the chiral anomaly, a phenomenon known from high-energy physics. The unique electronic structure of grey tin paves the way for its application as a functional material in novel spintronic devices.

Image: Left panel: Crystal structure of the α-Sn layer grown by molecular beam epitaxy on CdTe/GaAs substrate is subject to in-plane biaxial compressive strain (black arrows) and thus uniaxial tensile strain along normal to the layer. Magnetic field B can be applied in the layer plane; Middle panel: Dirac-like surface states revealed by Angle Resolved Photoemission Spectroscopy studies of α-Sn in Dirac semimetal phase induced by strain for B=0. Right panel: negative longitudinal magnetoresistance (current I ǁ B, see right inset) indicative of chiral anomaly in Weyl semimetal phase induced by an in-plane B. At low temperature, Shubnikov-de Hass oscillations are also visible. Insets to middle and right panels show calculated band structure of Dirac and Weyl semimetal phases, respectively.

Credit: Jakub Polaczyński, Valentine V. Volobuev

Effective and environmentally friendly removal of pharmaceuticals from wastewater under visible light

2024/06/272024/07/18

The research team working under the leadership of Prof. Anna Zielińska-Jurek from the Faculty of Chemistry at Gdańsk University of Technology, in cooperation with scientists from ASTRA beamline, developed and characterized a new semiconductor material based on bismuth orthovanadate (BiVO₄) and copper oxide sub-nanoclusters (CuO_x). This material, when exposed to visible light, is able to effectively remove pharmaceuticals in water. Measurements made at the SOLARIS synchrotron using X-ray absorption spectroscopy (XAS) revealed the oxidation state of copper oxides. The research results were published in the journal “Separation and Purification Technology” from Elsevier publisher.

The rapid development of medicine and the pharmaceutical industry has made pharmaceutical pollution one of the greatest environmental dangers. Some of the most frequently detected pharmaceuticals in Polish sewage are naproxen, a popular painkiller, and ofloxacin, an antibiotic. These compounds, found in rivers, lakes or seas, are persistent and not susceptible to biological degradation, and conventional methods used in sewage treatment plants are insufficient to remove them.

A promising way to remove pharmaceuticals from the aqueous phase is their degradation in the process of heterogeneous photocatalysis supported by peroxymonosulfate ions (HSO₅−, PMS). These processes are based on the generation of highly reactive radicals under sunlight, which, as a result of reaction with pollutants, are able to purify water.

Unusual switching mechanism of memristors based on nickel complexes

2024/06/262024/06/26

A group of scientists from the Academic Centre for Materials and Nanotechnology of the AGH University of Kraków, led by prof. dr. hab. Konrad Szaciłowski, with the help of specialists from the SOLARIS National Synchrotron Radiation Center, published the results of research on the unusual switching mechanism of memristors based on nickel complexes with dibenzotetraase annulenes. The work was published in the journal Advanced Electronic Materials published by Wiley.

The 21st century is undoubtedly marked by a revolution in the computerisation of humankind. The growing demand for computing computer power and Internet traffic results in an increasing electricity demand, which is also related to increasing carbon dioxide emissions by humans. However, some impassable limitations affect the further development of this technology, namely the heat wall and the memory wall. The heat wall is caused by transistor downscaling, which increases power density but leads to excessive heat production that cannot be efficiently dissipated from the chip. The memory wall is associated with long latency and high power consumption when transferring data between the memory and the CPU.

Image: Schematics of the structure and operation of the tested memristor.

Calculate the orientation of macromolecules in three-dimensional space

2024/06/132024/06/13

Scientists from the CIRI beamline are developing a method to calculate the orientation of macromolecules in three-dimensional space based on microscopic measurements using mid-infrared light polarized linearly at different angles. Reconstructing the experimental shape of the absorption dependency on polarization by fitting a nonlinear function to the data points obtained from the measurements allows for determining the angles that define the orientation of macromolecules in three-dimensional space, as well as a parameter describing the degree of sample organization. The measurements were conducted using an FPA array detector available at the FT-IR microscopy end-station on the CIRI beamline.

This method is non-destructive and does not require labeling, making it particularly useful for imaging and quantitatively determining the order parameters in various types of anisotropic polymer and biological samples.

The study focuses on the structural characterization of poly(lactic acid) (PLLA), a biodegradable polymer known for its polymorphism and significant potential in various applications due to its environmentally friendly nature. Scientists prepared thin PLLA films and, through thermal treatment, obtained a sample with varied morphology, including an amorphous phase, isolated spherulites, and larger clusters of the semi-crystalline phase. The reconstruction of the three angles of macromolecule orientation revealed that the morphological organization in the amorphous phase is random, and the molecular orientation differs from the semi-crystalline phase also in the third dimension in thin films.

Strain-control over the valley degree of freedom

2024/05/162024/05/16

Department of the Ecole Normale Supérieure Paris, France in collaboration with scientists from URANOS SOLARIS Centre have published in Physical Review Letters the results of their research on the Valley-Polarized Quantum Hall Phase Dirac System. The different local band minima – called valleys – of a multivalley 2D topological insulator have been independently characterized using ARPES experiments. An efficient control over their electronic population using mechanical strain has been demonstrated.

In a semiconductor multivalley system, local electronic band minima occur at different momenta of the Brillouin zone. These valleys embody a new degree of freedom for the electrons and can be seen as pseudospins. Controlling the valley populations independently from each other is of prime interest to develop valleytronics – the technology of controlling the valley degree of freedom – and investigate interesting pseudospin phenomena such as skyrmions, charge density waves or quantum Hall ferromagnetism.

Using the URANOS beamline, we demonstrate a full control over the valley energy splitting as a function of in-plane biaxial strain in the IV-VI system Pb_1-xSn_xSe. The strain is determined by the lattice mismatch between the buffer and film layer, which depends on the Sn content. The band structure of several Pb_1-xSn_xSe 20 nm quantum wells have been measured near the two types of valleys in these materials, at the Γ ̅ and M ̅ points. As shown in Fig. 1, a huge amount of subband dispersions is observed, witnessing the high-resolution experiments at the URANOS beamline and the high-quality of the samples.

ARPES is one of the rare experimental techniques to independently assess band structure properties near selected momenta of the Brillouin zone. In this way, the relative energy position of the band minima near the Γ ̅-point and the M ̅-point can be measured with respect to the Fermi energy. As strain is increased, the bands at the M ̅-point are seen to shift upward in energy compared to the bands near the Γ ̅-point (see Fig. 1). The valley energy splitting, represented by Δ _l-o, is found to be very sensitive to strain and varies as 160 meV per 1 % strain, twice than the AlAs system for instance.

This work has shown the very efficient valley control using strain in the IV-VI materials, and has allowed for studying valley-polarized quantum Hall phases in tra nsport experiments, where chiral edge states of only one valley or the other are observed. This ARPES study demonstrates a key properties for the development of valleytronics devices based on Pb_1-xSn_xSe system.

The relationship between the structure of polyurethane frameworks and the structural and superconducting properties of Y-123 foams

2024/04/162024/04/24

A Polish team of researchers led by Dr. Paweł Pęczkowski from the Institute of Physical Sciences, Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszyński University used the PIRX beam to study the properties of the electronic structure of superconducting foams obtained on the basis of polyurethane foams. The research results were published in the Journal of the European Ceramic Society published by Elsevier.

High-temperature superconductors (HTS) are most often produced in one of three varieties – thin film, wire (tape) and loose. This division results from the properties of these superconductors, which originate from their microstructure. High-temperature superconductors can be produced in a fourth variant with a foam structure. Superconductors with a foam structure have a much shorter cooling time, so the transition or return to the superconducting state from the normal state is much faster than in the case of solid samples manufactured using the top-seeded infiltration-growth (TSIG) method. Additionally, they are lightweight and exhibit fewer micro-cracks, which are the main factor limiting the critical current density in solid superconducting samples. These unique features make superconducting foams an excellent material for space applications, where it is necessary to use strong and light sources of magnetic fields to build, for example, docking mechanisms for space vehicles and ion engines. However, before superconducting foams are used, several basic questions need to be answered: what is the impact of changes in the foam structure (e.g. size and shape of pores) on superconducting properties, how does current flow in the three-dimensional structure of the foam and what is its impact on the properties related to ability to anchor vortexes (pinning centers).

Image: (a) Y-211 foam before and (b) after Y-035 infiltration process; (c) Y-123 – final foam levitation in a magnetic field

The special role of magnetic Ni ions in the electronic structure

2024/03/192024/03/20

Researcher from the Institute of Physics in Zagreb, in collaboration with scientists from AGH University of Krakow, Solaris synchrotron, Jagiellonian University, University of Zagreb, Institute of Nuclear Physics PN, and TU Wien, revealed the electronic structure of nickel intercalated 2H-NbS₂. The collaboration between experiment and theory provided insight into the special role of magnetic Ni ions in the electronic structure. The measured spectra and theoretical analysis indicate zero algebraic sum of hybridization integrals of relevant Ni orbitals and the conducting planes of the host material.

Two-dimensional magnetic materials are of great interest from the fundamental point of view and for applications. In particular, the magnetic sublayers, introduced by intercalation into the van der Waals gaps of the host transition metal dichalcogenides, are known to produce various magnetic states depending on the choice of magnetic intercalates, with some being tunable by pressure and doping. The magnetic intercalates strongly modify the electronic coupling between layers of the host compound. Understanding the origins of such variability, starting from the underlying electronic structure, is a significant challenge. By using angle-resolved photoelectron spectroscopy (ARPES) with various photon energies and ab initio electronic structure calculations, the study revealed the electronic structure of Ni₁/₃NbS₂.

Image: Fig 1. Schematic image of strong spin-selective hybridization between NbS₂ layers provided by intercalated magnetic ions (Ni, Co). The symmetries of dominant bridging orbitals in (a) Ni₁/₃NbS₂ and (b) Co₁/₃NbS₂. (c) The calculated band structures that show the type of magnetic ordering strongly affect the electronic structure. (d) The Fermi surface observed by ARPES. The magnetic fluctuations at bridging sites are prone to produce a strong electron correlation effect at the Fermi level (shallow electron pockets indicated by red arrows), which is inaccessible by DFT+U calculations.

Credit: Yuki Utsumi Boucher

Sodium-ion batteries: How doping works

2024/02/202024/02/22

Sodium-ion batteries still have a number of weaknesses that could be remedied by optimising the battery materials. One possibility is to dope the cathode material with foreign elements. A team from HZB and Humboldt-Universität zu Berlin has now investigated the effects of doping with Scandium and Magnesium. The scientists collected data at the X-ray sources BESSY II, PETRA III, and SOLARIS to get a complete picture and uncovered two competing mechanisms that determine the stability of the cathodes.

Lithium-ion batteries (LIB) have the highest possible energy density per kilogramme, but lithium resources are limited. Sodium, on the other hand, has a virtually unlimited supply and is the second-best option in terms of energy density. Sodium-ion batteries (SIBs) would therefore be a good alternative, especially if the weight of the batteries is not a major concern, for example in stationary energy storage systems.

However, experts are convinced that the capacity of these batteries could be significantly increased by a targeted material design of the cathodes. Cathode materials made of layered transition metal oxides with the elements nickel and manganese (NMO cathodes) are particularly promising. They form host structures in which the sodium ions are stored during discharge and released again during charging. However, there is a risk of chemical reactions which may initially improve the capacity, but ultimately degrade the cathode material through local structural changes. This has the consequence of reducing the lifetime of the sodium-ion batteries.

Image: The schematic illustration shows a sodium ion battery: The positive electrode or cathode (left) consists of layered transition metal oxides which form a host structure for sodium ions. The transition metal nickel can be replaced either by magnesium or scandium ions.

Credit: HZB

New method of data quality improvement by noise removal

2024/02/122024/02/15

Scientists from the CIRI beamline have found a way to accelerate infrared imaging of biological tissues. Their solution will enable faster diagnosis of cancer thanks to denoising. You can read about the MNF2 method they developed in the journal “Chemometrics and Intelligent Laboratory System”. With this discovery, researchers significantly enhanced the measurement capabilities using the FPA array detector available at the FT-IR microscopy end station at the CIRI beamline.

In infrared imaging (IR), a key aspect of the analysis of biological tissues is the time necessary to perform the measurement. This is particularly important in terms of the diagnosis of tumors in tissues – where it can be used as an alternative to conventional histopathological staining as well as support for histopathologists in the diagnosis of the disease. One of the approaches to shorten the measurement time is to reduce the number of measured scans to, e.g. 4 – which are employed in studies on tissue classification – instead of the typically measured 128 or 64 scans. This results in increased noise in the spectra. However, by using data pre-processing methods, specifically denoising, they can obtain data qualitatively comparable to those measured with a large number of scans. Nowadays, the method gaining popularity among researchers working with IR imaging is the Minimum Noise Fraction (MNF) method. This method is based on the eigenvalue decomposition. In the first step: the noise matrix is calculated and decomposed. This estimate is made by subtracting the signal from neighboring pixels, assuming that they do not differ in terms of chemical composition – the only difference should be noise.

Image: On the left side, a breast needle biopsy imaged with FT-IR is presented, with three interesting tissue regions: necrosis, blood, and fiber. On the right side, FT-IR spectra are shown (coming from pixels marked with filled squares), for visual comparison of denoising methods performance.

Direct observation of the spin texture and the Rashba effect of a ferroelectric semiconductor

2024/02/062024/02/06

Unprecedentedly high-quality ARPES experiments have been performed at the URANOS beamline and revealed the band and spin behavior in a semiconductor undergoing a ferroelectric transition. The temperature dependent measurements unraveled the impact of the ferroelectric phase transition on the electronic spin texture.

Ferroelectric Rashba semiconductor are a sought-after new class of materials due to their remarkable properties. Their spin texture is controllable by an external electric field, which makes these multifunctional materials highly attractive for spintronics technology like spin-FET transistors or bipolar memories. However, their experimental demonstrations are still rare and elusive.
A ferroelectric phase results in a permanent electric polarization intrinsic to the material, which lifts the spin degeneracy of the electronic bands. This spin splitting is called the Rashba effect and has been directly observed using the ARPES setup of the URANOS beamline (see Fig. 1). Temperature dependent measurements (10 to 300 K) have revealed the emergent Rashba splitting when temperature is decreased below the critical temperature of the phase transition. In this way, the ferroelectric phase of the Pb1-xGexTe compounds have been fully probed in a wide range of composition (x=0 to 10 %). Remarkably, the ferroelectric behavior is seen to persist down to very thin film thickness (8 nm).
The high-quality ARPES images have allowed for an accurate quantitative evaluation of the Rashba spin-texture in the ferroelectric phase and its evolution with temperature.

Image: Temperature dependent ARPES spectra measured on a Pb_0.93Ge_0.07Te 8 nm quantum well. The band degeneracy lifting is clearly observed above a critical temperature Tc, which indicates the ferroelectric phase transition. The Rashba effect is seen to increase as temperature is decreased.

Detection of early pancreatic cancer lesions using infrared and machine learning

2024/01/292024/02/01

A group of researchers from the CIRI beamline in their latest publication entitled Pancreatic intraepithelial neoplasia detection and duct pathology grading using FT-IR imaging and machine learning published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy presented the results of their PanIN classification method, which provides opportunities for early recognition of changes in the cells lining the pancreatic ducts using infrared and machine learning.

Pancreatic intraepithelial neoplasia (PanIN) manifests itself by changes in the cells lining the pancreatic ducts. It is an early pre-cancerous lesion divided into low-grade and high-grade PanIN. In particular, high-grade PanIN is a lesion that often leads to Pancreatic ductal adenocarcinoma (PDAC). In the case of pancreatic cancer, due to the lack of characteristic symptoms of the disease in its early stage, patient survival is low. The basic examination performed to diagnose the disease is to take a fine-needle biopsy from the patient. The most common method of treatment is to remove part of the tissue affected by cancer, which increases the patient’s chances of survival, especially if it is done at an early stage of the disease. Therefore, it is so important to understand the biochemistry of lesions such as PanIN and their progression to cancer.

Image : Scheme of sample collection (figure upper part), and FT-IR imaged TMA processing using: Random Forest classification (figure middle part), PLS Regression (figure bottom part).

Light for Ukraine – conference focused on research infrastructure

2024/01/232024/01/25

The SOLARIS Centre hosted second time international meeting with the Ukrainian scientific community, entitled “Light for Ukraine.” The conference set directions for European-Ukrainian activities aimed at to support initiatives using synchrotron radiation.

The second edition of the “Light for Ukraine” workshop, has just ended. Nearly 130 scientists representing the European and Ukrainian scientific communities participated in the workshop.
The workshop focused on the planned Ukrainian synchrotron beamline concept: “Nano and micro X-ray spectroscopy beamline” at SOLARIS within the LEAPS initiative.

Research on the structure of human cold receptor TRPM8

2023/11/222023/11/24

Researchers from the Laboratory of Protein Structure at the International Institute of Molecular and Cell Biology in Warsaw, led by Prof. Marcin Nowotny, used the KRIOS cryoelectron microscope located at the SOLARIS National Synchrotron Radiation Centre to study the human TRPM8 protein.

The structure they obtained will enable a better understanding of the binding mechanism of small-molecule compounds affecting the activity of this ion channel. It will facilitate the design of new small-molecule compounds that can be used as therapeutics to treat numerous diseases associated with TRPM8 protein, such as neuropathic pain, irritable bowel syndrome, oropharyngeal dysphagia, chronic cough, and hypertension. As an example, in collaboration with scientists from Italy led by Dr. Carmine Talarico of Dompé Farmaceutici SpA, they have performed modeling of the binding of icilin, a small-molecule compound showing 200 times stronger TRPM8 channel activation than menthol.

Image: Structure of human cold receptor TRPM8

Credit: Mariusz Czarnocki-Cieciura

What makes parrots have colorful feathers?

2023/10/302023/11/02

Dr. Peter Mojzeš Institute of Physics of Charles University, Faculty of Mathematics and Physic Charles University and Dr. Jindřich Brejcha Department of Philosophy and History of Science, Faculty of Science, Charles University in Prague – conducted the research on a CIRI beamline, studying how parrots produce the colors of their feathers.

The multi-colored plumage of parrot feathers arouses admiration and delight, but where did all these colors actually come from? How birds managed to develop such a range of colors and how has it evolved over the centuries? A group of researchers led by Dr. Miguel Carneiro from CIBIO (Research Centre in Biodiversity and Genetic Resources – InBIO Associate Laboratory) in Portugal decided to answer these questions.

Dr. Jindřich Brejcha explained what their research is about – Specifically, we are interested in molecular differences of polyene pigment contained within parrots’ feathers. We use Raman spectroscopy combined with mass spectroscopy to look at the structure of molecules causing parrot color. However, due to the resonance Raman effect for the excitation throughout the visible region and high Raman cross-section of the C-C and C=C vibrations, only a few Raman bands related to the vibrational modes of the main polyene chain and disproportionately enhanced are visible in the Raman spectra. Raman bands associated with vibrations of functional end groups are hidden in stochastic noise. Hence, to overcome this shortcoming of Raman microscopy while preserving the same spatial resolution, O-PTIR microscopy seems to be a promising candidate method.

Exploration of the mechanism of phase formation in pulsed laser irradiation of suspensions

2023/10/042023/10/04

The cooperation between scientists of the Institute of Nuclear Physics Polish Academy of Sciences and ASTRA beamline resulted in a better understanding of the mechanism of phase formation in pulsed laser irradiation of suspension (PLIS) for submicron heterostructure formation.

According to Shakeri, et al., irradiation of suspended nanoparticles using laser pulses results in formation submicron particles by the following mechanism.

Suspended agglomerates are heated by the energy absorption of a laser pulse according to their absorption efficiency, depending on the wavelength-dependent absorption cross section calculated by Mie theory. The absorbed energy is directly proportional to the laser fluence and the surface area of the agglomerate. On the other hand, the pulse factors influence the temperature development, so that the pulse shape is responsible for heat conservation, while the pulse duration controls the heat release. Cooling of the particles and re-agglomeration of the irradiated particles occurs in the time between pulses by synergistic agitation of the suspension. In addition, pulse repetition affects particle growth by changing the probability of the probe. The heating-cooling process is repeated depending on the probability of the probe in the system, resulting in alternative particle growth limited by the melting possibility of agglomerates. More importantly, the temperature of agglomerates not only determines their thermodynamically stable phases but also affects the rate of solvent dissociation during interfacial solvent-particle interactions. Although the solvent bath is at ambient temperature, due to the transparency to the laser beam, the kinetic energy of the molecules coming into contact with the surface of the heated particles is very high, resulting in the bond breaking/formation at the interface between the dissociated solvent and the heated particles. The dissociated species diffuse into the sphere where the oxidation/reduction reactions take place according to their nature.

EXAFS spectra measured in ASTRA beamline of SOLARIS were initially used for invesigation of oxidation evaluation of samples. Linear combination fitting (LCF) of EXAFS spectra also used using reference spectra for measurement of exact composition of samples. Chemical composition variations detected by LCF helped the scientists to detect chemical/physical type of phase transition during PLIS phase formation. Gaussian deconvolution of XANES spectra showed the probable constituent transitions, which were later used for fitting of various phases in the system derived by calculated XANES spectra using Feff code.

Image: Figure 1. Mechanism of particle formation during PLIS.