Synchrotron Radiation Research Articles

High-resolution X-ray phase-contrast tomography of human placenta with different wavefront markers

Phase-contrast micro-tomography (CT) with synchrotron radiation can aid in the differentiation of subtle density variations in weakly absorbing soft tissue specimens. Modulation-based imaging (MBI) extracts phase information from the distortion of reference patterns, generated by periodic or randomly structured wavefront markers (e.g., gratings or sandpaper). The two approaches have already found application for the virtual inspection of biological samples. Here, we perform high-resolution CT scans of an unstained human placenta specimen, using MBI with both a 2D grating and sandpaper as modulators, as well as conventional propagation-based imaging (PBI). The 3D virtual representation of placenta offers a valuable tool for analysing its intricate branching villous network and vascular structure, providing new insights into its complex architecture. Within this study, we assess reconstruction quality achieved with all three evaluated phase-contrast methods. Both MBI datasets are processed with the Unified Modulated Pattern Analysis (UMPA) model, a pattern-matching algorithm. In order to evaluate the benefits and suitability of MBI for virtual histology, we discuss how the complexities of the technique influence image quality and correlate the obtained volumes to 2D techniques, such as conventional histology and X-ray fluorescence (XRF) elemental maps.

The Radio Fundamental Catalog. I. Astrometry

We present an all-sky catalog of absolute positions and estimates of correlated flux density of 21,942 compact radio sources determined from processing interferometric visibility data of virtually all very long baseline interferometry (VLBI) observing sessions at 2–23 GHz from 72 programs suitable for absolute astrometry collected for 30 yr. We used a novel technique of generation of a data set of fused observables that allowed us to incorporate all available data in our analysis. The catalog is the most complete and most precise to date. It forms the foundation and reference for positional astronomy, space geodesy, space navigation, and population analysis of active galactic nuclei (AGNs), and provides calibrators for phase referencing for differential astrometry and VLBI astrophysical observations. Its accuracy was evaluated through a detailed accounting of systematic errors, rigorous decimation tests, comparison of different data sets, and comparison with other catalogs. The catalog preferentially samples AGNs with strong contemporary parsec-scale synchrotron emission. Its milliarcsecond-level positional accuracy allows association of these AGNs with detections in a wide range of the electromagnetic spectrum from low-frequency radio to γ rays and high-energy neutrinos. We describe the innovative data processing and calibration technique in full detail, report the in depth analysis of random and systematic positional errors, and provide a list of associations with large surveys at different wavelengths.

Bayesian Approach to Equipartition Estimation of Magnetic Field Strength

Abstract Magnetic fields, together with cosmic rays (CRs), play an important role in the dynamics and evolution of galaxies, but are difficult to estimate. Energy equipartition between magnetic fields and CRs provides a convenient way to approximate magnetic field strength from radio observations. We present a new approach for calculating the equipartition magnetic field strength based on Bayesian methods. In this approach, the magnetic field is a random variable that is distributed according to a posterior distribution conditional on synchrotron emission and the size of the emitting region. It allows for the direct application of the general formulas for total and polarized synchrotron radiation without the need to invert these formulas, which has limited the equipartition method to highly simplified cases. We have derived the equipartition condition for the case of different low-energy breaks, slopes, and high-energy cutoffs of power-law spectra of the CR proton and electron distributions. The derived formalism was applied in the general case of a magnetic field consisting of both uniform and randomly oriented field components. The applied Bayesian approach naturally provides the uncertainties in the estimated magnetic field strengths resulting from the uncertainties in the observables and the assumed values of the unknown physical parameters. In the examples presented, we used two different Markov Chain Monte Carlo methods to generate the posterior distribution of the magnetic field. We have also developed a web application called BMAG that implements the described approach for different models and observational parameters of real sources.

Atacama Large Aperture Submillimeter Telescope (AtLAST) science: Probing the transient and time-variable sky

The study of transient and variable events, including novae, active galactic nuclei, and black hole binaries, has historically been a fruitful path for elucidating the evolutionary mechanisms of our universe. The study of such events in the millimeter and submillimeter is, however, still in its infancy. Submillimeter observations probe a variety of materials, such as optically thick dust, which are hard to study in other wavelengths. Submillimeter observations are sensitive to a number of emission mechanisms, from the aforementioned cold dust, to hot free-free emission, and synchrotron emission from energetic particles. Study of these phenomena has been hampered by a lack of prompt, high sensitivity submillimeter follow-up, as well as by a lack of high-sky-coverage submillimeter surveys. In this paper, we describe how the proposed Atacama Large Aperture Submillimeter Telescope (AtLAST) could fill in these gaps in our understanding of the transient universe. We discuss a number of science cases that would benefit from AtLAST observations, and detail how AtLAST is uniquely suited to contributing to them. In particular, AtLAST’s large field of view will enable serendipitous detections of transient events, while its anticipated ability to get on source quickly and observe simultaneously in multiple bands make it also ideally suited for transient follow-up. We make theoretical predictions for the instrumental and observatory properties required to significantly contribute to these science cases, and compare them to the projected AtLAST capabilities. Finally, we consider the unique ways in which transient science cases constrain the observational strategies of AtLAST, and make prescriptions for how AtLAST should observe in order to maximize its transient science output without impinging on other science cases.

Recent Progress on the Involvement of Formaldehyde in the Methanol-To-Hydrocarbons Reaction.

This review summarized the recent research progress on the crucial role of formaldehyde during the methanol-to-hydrocarbons (MTH) reaction. As a reaction intermediate, formaldehyde participates in the formation of carbon-carbon, the establish of dual-cycle, and the coking process of MTH reaction. Different techniques for formaldehyde detection in the study of MTH are also introduced.The conversion of methanol-to-hydrocarbons (MTH) over zeolite catalysts has been the subject of intense research since its discovery. Great effort has been devoted to the investigation of four key topics: the initiation of C-C bonds, the establishment of hydrocarbon pool (HCP), the adjustment of product selectivity, and the deactivation process of catalysts. Despite 50 years of study, some mechanisms remain controversial. However, an intermediate species, formaldehyde (HCHO), has recently garnered considerable attention for its influence on the entire MTH process. The discovery of HCHO and its significant role in the MTH process has been facilitated by the application of in situ analytical techniques, such as synchrotron radiation photoionization mass spectrometry (SR-PIMS) and photoelectron photoion coincidence spectroscopy (PEPICO). It is now revealed that HCHO is involved in the initiation, propagation, and termination process of MTH reaction. Such mechanistic understanding of HCHO's involvement has provided valuable insights for optimizing the MTH process.

Dopant site analysis of heavily Si-doped GaAs using a combination of electron microscopy and synchrotron radiation

Dopant site analysis of heavily Si-doped GaAs using a combination of electron microscopy and synchrotron radiation

Computational microscopy with coherent diffractive imaging and ptychography.

Microscopy and crystallography are two essential experimental methodologies for advancing modern science. They complement one another, with microscopy typically relying on lenses to image thelocal structuresof samples, and crystallography using diffraction to determine the global atomic structure of crystals. Over the past two decades, computational microscopy, encompassing coherent diffractive imaging (CDI) and ptychography, has advanced rapidly, unifying microscopy and crystallography to overcome their limitations. Here, I review the innovative developments in CDI and ptychography, which achieve exceptional imaging capabilities across nine orders of magnitude in length scales, from resolving atomic structures in materials at sub-ångstrom resolution to quantitative phase imaging of centimetre-sized tissues, using the same principle and similar computational algorithms. These methods have been applied to determine the 3D atomic structures of crystal defects and amorphous materials, visualize oxygen vacancies in high-temperature superconductors and capture ultrafast dynamics. They have also been used for nanoscale imaging of magnetic, quantum and energy materials, nanomaterials, integrated circuits and biological specimens. By harnessing fourth-generation synchrotron radiation, X-ray-free electron lasers, high-harmonic generation, electron microscopes, optical microscopes, cutting-edge detectors and deep learning, CDI and ptychography are poised to make even greater contributions to multidisciplinary sciences in the years to come.

Detection of Extended X-Ray Emission around the PeVatron Microquasar V4641 Sgr with XRISM

Abstract A recent report on the detection of very-high-energy gamma rays from V4641 Sagittarii (V4641 Sgr) up to ≈0.8 PeV has made it the second confirmed “PeVatron” microquasar. Here we report on the observation of V4641 Sgr with X-Ray Imaging and Spectroscopy Mission (XRISM) in 2024 September. Thanks to the large field of view and low background, the CCD imager Xtend successfully detected for the first time X-ray extended emission around V4641 Sgr with a significance of ≳4.5σ and >10σ based on our imaging and spectral analysis, respectively. The spatial extent is estimated to have a radius of 7′ ± 3′ (13 ± 5 pc at a distance of 6.2 kpc) assuming a Gaussian-like radial distribution, which suggests that the particle acceleration site is within ~10 pc of the microquasar. If the X-ray morphology traces the diffusion of accelerated electrons, this spatial extent can be explained by either an enhanced magnetic field (∼80 μG) or a suppressed diffusion coefficient (∼1027 cm2 s−1 at 100 TeV). The integrated X-ray flux, (4–6) × 10−12 erg s−1 cm−2 (2–10 keV), would require a magnetic field strength higher than the Galactic mean (≳8 μG) if the diffuse X-ray emission originates from synchrotron radiation and the gamma-ray emission is predominantly hadronic. If the X-rays are of thermal origin, the measured extension, temperature, and plasma density can be explained by a jet with a luminosity of ∼2 × 1039 erg s−1, which is comparable to the Eddington luminosity of this system.

Advances in Constructing Efficient Photocatalytic Systems for Hydrogen Peroxide Production: Insights from Synchrotron Radiation Research

Advances in Constructing Efficient Photocatalytic Systems for Hydrogen Peroxide Production: Insights from Synchrotron Radiation Research

30 years of Journal of Synchrotron Radiation and synchrotron science.

Journal of Synchrotron Radiation (JSR) came into being with the publication of its inaugural issue in October 1994 that contained 15 full articles comprising 100 pages. Thirty years of JSR has coincided with several Nobel Prizes that have arisen from the work undertaken on synchrotron radiation sources, with the first of these awarded to Sir John Walker in 1997, just three years after the launch of JSR, and celebrated on the front cover of the journal's July 1999 issue. This article provides an insight into the motivation as well as the journey of establishing this important journal for the IUCr and the synchrotron radiation community which has continued to grow. We also highlight some of the well cited papers for each of the five-year-periods during these 30 years and demonstrate how the journal has become the natural home for all aspects of synchrotron radiation science and technology.

SiC free-standing membrane for X-ray intensity monitoring in synchrotron radiation beamlines.

For many synchrotron radiation experiments, it is critical to perform continuous, real-time monitoring of the X-ray flux for normalization and stabilization purposes. Traditional transmission-mode monitors included metal mesh foils and ionization chambers, which suffered from low signal stability and size constraints. Solid-state detectors are now considered superior alternatives for many applications, offering appealing features like compactness and signal stability. However, silicon-based detectors suffer from poor radiation resistance, and diamond detectors are limited in scalability and are expensive to produce. Silicon carbide (SiC) has recently emerged as an alternative to both materials, offering a high-quality mature semiconductor with high thermal conductivity and radiation hardness. This study focuses on a systematic exploration of the SiC `free-standing membrane' devices developed by SenSiC GmbH. In particular, we performed in-depth sensor-response analysis with photon energies ranging from tender (1.75 keV) to hard (10 keV) X-rays at the Four-Crystal Monochromator beamline in the PTB laboratory at the synchrotron radiation facility BESSY II, studying uniformity of transmission and responsivity compared with the state-of-the-art beam monitors. Furthermore, we theoretically evaluated the expected signal in different regions of the sensors, also taking into account the effect of charge diffusion from the SiC substrate in the case of the not-carved region.

Crab pulsar: IXPE observations reveal unified polarization properties in the optical and soft X-ray bands

We present a phase-dependent analysis of the polarized emission from the Crab pulsar based on three sets of observations by the Imaging X-ray Polarimetry Explorer (IXPE). We found that a phenomenological model involving a simple linear transformation of the Stokes parameters adequately describes the IXPE data. This model enabled us to establish a connection between the polarization properties of the Crab pulsar in the optical and soft X-ray bands for the first time, which suggests a common underlying emission mechanism in these bands that likely is synchrotron radiation. In particular, the phase-dependent polarization degree in X-rays for the pure pulsar emission shows similar features, but is reduced by a factor ≈(0.46 − 0.56) compared to the optical band (when we accounted for the contribution of the knot in the optical), which implies an energy-dependent polarized emission. Using this model, we also studied the polarization angle swing in the X-rays and identified a potentially variable phase shift at the interpulse relative to the optical band, alongside a phase shift that is marginally consistent with zero and persists at the main pulse. While the origin of this variability is unknown and presents a new challenge for the theoretical interpretation, our findings suggest that the emission mechanism for the main pulse is likely located far from the neutron star surface, perhaps near to or beyond the light cylinder, and that it does not operate in the inner magnetosphere, where vacuum birefringence is expected to be at work. Ignoring the phase shifts would result in identical phase-dependent polarization angles between the optical and X-ray bands for the pure pulsar emission.

Fluorescent nanodiamond scintillators for beam diagnostics of EUV and soft X-ray in photolithographic applications.

Extreme ultraviolet (EUV) lithography is a cutting-edge technology in contemporary semiconductor chip manufacturing. Monitoring the EUV beam profiles is critical to ensuring consistent quality and precision in the manufacturing process. This study uncovers the practical use of fluorescent nanodiamonds (FNDs) coated on optical image sensors for profiling EUV and soft X-ray (SXR) radiation beams. We employed a positive electrospray ion source to deposit 100 nm FNDs onto indium tin oxide (ITO)-coated substrates, forming 1 μm thick films. The scintillation films exhibited approximately 50% transparency in the visible region and could emit red fluorescence from neutral nitrogen-vacancy (NV0) centers in the FNDs when exposed to EUV/SXR radiation. We evaluated the performance of a device featuring an FND coating on a fiber optic plate (FOP) attached to the sensor of a complementary metal-oxide semiconductor (CMOS) camera using synchrotron radiation across the 80-1400 eV energy range. At 91.8 eV (or a wavelength of 13.5 nm), the fiber-coupled device exhibited a noise-equivalent power density of 0.25 μW cm-2 Hz-1/2, approximately eight times lower than that of an f/1.0 lens-coupled system. This enhanced sensitivity makes the FND/FOP-based detection system useful for beam profiling of various EUV/SXR radiation sources. Our results highlight the promising potential of electrosprayed FND scintillators as a cost-effective and versatile diagnostic tool for advancing next-generation photolithography.

Exploiting fourth-generation synchrotron radiation for enzyme and photoreceptor characterization.

The upgrade of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France to an Extremely Brilliant Source (EBS) is expected to enable time-resolved synchrotron serial crystallography (SSX) experiments with sub-millisecond time resolution. ID29 is a new beamline dedicated to SSX experiments at ESRF-EBS. Here, we report experiments emerging from the initial phase of user operation at ID29. We first used microcrystals of photoactive yellow protein as a model system to exploit the potential of microsecond pulses for SSX. Subsequently, we investigated microcrystals of cytochrome c nitrite reductase (ccNiR) with microsecond X-ray pulses. CcNiR is a decaheme protein that is ideal for the investigation of radiation damage at the various heme-iron sites. Finally, we performed a proof-of-concept subsecond time-resolved SSX experiment by photoactivating microcrystals of a myxobacterial phytochrome.

Towards targeted cancer therapy: Synthesis, characterization, and biological activity of a new Cu(II)-ibuprofen-2,2'-dipyridylamine metal complex.

This work reports the synthesis of a copper metal complex with the nonsteroidal anti-inflammatory drug (NSAID) ibuprofen, and 2,2'-dipyridylamine employing microwave-assisted synthesis (MWAS). To the best of authors knowledge, this is the first study reporting a NSAID-based complex achieved through MWAS. The coordination compound was characterised by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetry, and ultraviolet-visible spectrophotometry. Additionally, the crystal structure of the copper metal complex was elucidated using single-crystal X-ray diffraction with synchrotron radiation. The compound's interaction with the biomolecules bovine serum albumin (BSA) and calf-thymus DNA (CT-DNA), was assessed through UV-Vis, circular dichroism, and fluorescence spectroscopy. Our findings demonstrate that the metal complex effectively binds to BSA, causing a reduction in its intrinsic fluorescence and α-helical content, and shows a capacity for intercalation between CT-DNA base pairs. Finally, the copper compound exhibited promising in vitro antitumoral activities against human breast cancer cell lines (MCF-7 and MDA-MB-231), as evaluated by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay (although a similar cytotoxic effect against a non-tumoral epithelial cancer cell line, MCF-12A, was found), and increased oxidative stress levels as assessed by the TBARS (thiobarbituric acid reactive substances) assay and by evaluating glutathione levels. The results suggest that the metal complex promotes lipid peroxidation by increasing oxidative stress levels, leading to a reduction in viability of the two breast cancer cell lines.

A compact furnace for in-situ studies on high-temperature reactivity of coke using synchrotron radiation SAXS

The study of coke reactivity under high temperature conditions is crucial for understanding its behavior in industrial processes. This study presents a novel compact heating furnace, developed for in-situ synchrotron small-angle X-ray scattering (SAXS) studies on the high-temperature reactivity of coke. The furnace achieves temperatures up to 1400∘C at a heating rate of 12∘C/min and enables steam introduction, simulating industrial conditions. Combination of the furnace with the in-situ SAXS setup at synchrotron radiation facilities facilitates real-time monitoring of structural changes at nanoscale in coke under various temperature and atmospheric conditions. This advancement offers a robust experimental platform for studying coke reactivity, with potential benefits for optimizing industrial processes and reducing environmental impact.

Picometre-level surface control of a closed-loop, adaptive X-ray mirror with integrated real-time interferometric feedback.

We provide a technical description and experimental results of the practical development and offline testing of an innovative, closed-loop, adaptive mirror system capable of making rapid, precise and ultra-stable changes in the size and shape of reflected X-ray beams generated at synchrotron light and free-electron laser facilities. The optical surface of a piezoelectric bimorph deformable mirror is continuously monitored at 20 kHz by an array of interferometric sensors. This matrix of height data is autonomously converted into voltage commands that are sent at 1 Hz to the piezo actuators to modify the shape of the mirror optical surface. Hence, users can rapidly switch in closed-loop between pre-calibrated X-ray wavefronts by selecting the corresponding freeform optical profile. This closed-loop monitoring is shown to repeatably bend and stabilize the low- and mid-spatial frequency components of the mirror surface to any given profile with an error <200 pm peak-to-valley, regardless of the recent history of bending and hysteresis. Without closed-loop stabilization after bending, the mirror height profile is shown to drift by hundreds of nanometres, which will slowly distort the X-ray wavefront. The metrology frame that holds the interferometric sensors is designed to be largely insensitive to temperature changes, providing an ultra-stable reference datum to enhance repeatability. We demonstrate an unprecedented level of fast and precise optical control in the X-ray domain: the profile of a macroscopic X-ray mirror of over 0.5 m in length was freely adjusted and stabilized to atomic level height resolution. Aside from demonstrating the extreme sensitivity of the interferometer sensors, this study also highlights the voltage repeatability and stability of the programmable high-voltage power supply, the accuracy of the correction-calculation algorithms and the almost instantaneous response of the bimorph mirror to command voltage pulses. Finally, we demonstrate the robustness of the system by showing that the bimorph mirror's optical surface was not damaged by more than 1 million voltage cycles, including no occurrence of the `junction effect' or weakening of piezoelectric actuator strength. Hence, this hardware combination provides a real time, hyper-precise, temperature-insensitive, closed-loop system which could benefit many optical communities, including EUV lithography, who require sub-nanometre bending control of the mirror form.

SRCES: a simulation program for collective effects in electron storage rings

Collective effects are important in the physics design of electron storage rings, especially for the fourth-generation synchrotron light source, where the collective effects are more severe than before and limit maximum stored beam current. To estimate beam collective effects, besides theoretical analysis, numerical tracking methods are necessary for obtaining more accurate and comprehensive results. To systematically study the comprehensive influence of wakefields and various damping mechanisms, we developed a new code Storage Ring Collective Effects Simulator (SRCES), which is a tracking code based on macroparticle model in 6-dimensional phase space. Several models are employed to handle various processes of particle motion. The modified transfer matrix and high order Taylor transfer map are used to solve particle motion under external electro-magnetic fields. A simplified equivalent damping and excitation model is used to represent the effects of synchrotron radiation on particle motion. The kick model is used to represent the influence of wakefields and RF cavity. Furthermore, the wake function data can be input as numerical arrays directly or through specific impedance models. In this paper, we describe the basic theory foundation, functions and benchmarked results of the code SRCES. Then, SRCES is used to conduct preliminary research on the collective effects of the Hefei Advanced Light Facility storage ring.

Micro- and milli-fluidic sample environments for in situ X-ray analysis in the chemical and materials sciences.

X-ray-based methods are powerful tools for structural and chemical studies of materials and processes, particularly for performing time-resolved measurements. In this critical review, we highlight progress in the development of X-ray compatible microfluidic and millifluidic platforms that enable high temporal and spatial resolution X-ray analysis across the chemical and materials sciences. With a focus on liquid samples and suspensions, we first present the origins of microfluidic sample environments for X-ray analysis by discussing some alternative liquid sample holder and manipulator technologies. The bulk of the review is then dedicated to micro- and milli-fluidic devices designed for use in the three main areas of X-ray analysis: (1) scattering/diffraction, (2) spectroscopy, and (3) imaging. While most research to date has been performed at synchrotron radiation facilities, the recent progress made using commercial and laboratory-based X-ray instruments is then reviewed here for the first time. This final section presents the exciting possibility of performing in situ and operando X-ray analysis in the 'home' laboratory and transforming microfluidic and millifluidic X-ray analysis into a routine method in physical chemistry and materials research.

Development and testing of a dual-frequency real-time hardware feedback system for the hard X-ray nanoprobe beamline of the SSRF.

A novel dual-frequency real-time feedback system has been developed to simultaneously optimize and stabilize beam position and energy at the hard X-ray nanoprobe beamline of the Shanghai Synchrotron Radiation Facility. A user-selected cut-off frequency is used to separate the beam position signal obtained from an X-ray beam position monitor into two parts, i.e. high-frequency and low-frequency components. They can be real-time corrected and optimized by two different optical components, one chromatic and the other achromatic, of very different inertial mass, such as Bragg monochromator dispersive elements and a pre-focusing total external reflection mirror. The experimental results shown in this article demonstrate a significant improvement in position and energy stabilities. The long-term beam angular stability clearly improved from 2.21 to 0.92 µrad RMS in the horizontal direction and from 0.72to 0.10 µrad RMS in the vertical direction.