Researchers Generate Continuous-Wave Terawatt-Scale Attosecond X-Ray Pulses at SHINE

In a new study, researchers from the Shanghai Advanced Research Institute of Chinese Academy of Sciences and Deutsches Elektronen-Synchrotron DESY report that a Continuous-wave (CW) X-ray free-electron lasers (XFELs) could generate terawatt-class attosecond X-ray pulses at megahertz repetition rates, based on comprehensive simulations of Shanghai High-repetition-rate XFEL and Extreme Light Facility (SHINE). Notably, the proposed approach operates within the existing machine configuration and requires no additional hardware.The findings were published in Ultrafast Science and were selected as the Featured Article on its homepage.

In a new study, researchers from the Shanghai Advanced Research Institute of Chinese Academy of Sciences and Deutsches Elektronen-Synchrotron DESY report that a Continuous-wave (CW) X-ray free-electron lasers (XFELs) could generate terawatt-class attosecond X-ray pulses at megahertz repetition rates, based on comprehensive simulations of Shanghai High-repetition-rate XFEL and Extreme Light Facility (SHINE).Notably, the proposed approach operates within the existing machine configuration and requires no additional hardware.The findings were published in Ultrafast Science and were selected as the Featured Article on its homepage.An attosecond (10⁻¹⁸ seconds) corresponds to the natural timescale of electron motion in matter. X-rays provide element specificity and atomic-scale sensitivity, making them powerful probes of ultrafast dynamics in complex materials and chemical systems. However, generating high-power attosecond X-ray pulses at high repetition rates remains a major challenge.CW XFEL, driven by superconducting accelerators, offer a promising route toward this goal. These facilities can deliver XFEL pulses at megahertz repetition rates, enabling high-statistics measurements and greatly improved experimental stability, provided that attosecond pulse durations can be realized.SHINE, as one of the first hard X-ray CW XFEL facilities under construction, provides a unique platform for exploring high-repetition-rate attosecond science.Fig.1 Schematic layout of the AttoSHINE and the corresponding evolution of the electron-beam longitudinal phase space （Image by SARI)The scheme exploits a self-chirping effect within the electron beam, where collective beam interactions naturally imprint a strong energy chirp onto a small fraction of the bunch.The chirped beam is subsequently transported through a specially designed dogleg lattice located immediately upstream of the undulator. The lattice is optimized to provide strong longitudinal compression while suppressing transverse dispersion, producing an ultranarrow, high-current spike that emits an intense attosecond X-ray pulse.As the method relies on beam transport optimization rather than new hardware, it provides a practical and scalable route for CW XFELs to reach the attosecond regime.Fig.2 FEL simulation results at 6 keV (Image by SARI)For hard X-rays at 6 keV, simulations predict pulses with an average duration of approximately 300 attoseconds and peak powers approaching 0.8 terawatts. For soft X-rays at 1 keV, pulse durations of around 470 attoseconds with comparable terawatt-level peak powers are obtained.The high repetition rate would further enable rapid statistical averaging, significantly improving sensitivity to weak or rare ultrafast phenomena while enhancing experimental stability.Such sources could open the door to nonlinear attosecond X-ray science, enabling multi-photon and higher-order electronic processes to be explored at atomic length scales. They could also enable attosecond X-ray crystallography, allowing direct observation of electron-density evolution during chemical reactions and phase transitions.Fig.3 Superradiant behavior in the evolution of a terawatt attosecond pulse (Image by SARI)

Researchers Propose a Dynamic Formation Mechanism of Enzymatic Nanobubbles for Nerve Injury Treatment

A joint research team led by Prof. ZHANG Lijuan from the Shanghai Advanced Research Institute, Chinese Academy of Sciences and Tongji University proposed a peptide-stabilized lactate oxidase and catalase system, which can effectively deliver oxygen to cells and tissues in Nerve Injury Treatment. ​The findings were published in Cell Biomaterials.

A joint research team led by Prof. ZHANG Lijuan from the Shanghai Advanced Research Institute, Chinese Academy of Sciences and Tongji University proposed a peptide-stabilized lactate oxidase and catalase system, which can effectively deliver oxygen to cells and tissues in Nerve Injury Treatment.The findings were published in Cell Biomaterials.Nanobubbles hold tremendous potential in the field of biomedical gas delivery. Their extensive gas-liquid interface and relatively high internal pressure endow them with gas transport efficiency far superior to that of traditional methods.By investigating the formation, stabilization/diffusion processes and biological effects of enzyme-driven nano-bubbles, the joint research team proposed that the locally high concentrations of gaseous molecules produced in efficient biocatalytic centers and hydrophobic regions within microdomain structures enable enzyme molecules to serve as ideal bioreactors for nanobubble fabrication.Inspired by enzyme complexes in metabolic processes, researchers constructed a peptide-stabilized lactate oxidase/catalase (LOx/CAT@PNFs) system. This system utilized endogenous substances (lactate and hydrogen peroxide) in living organisms to generate oxygen nanobubbles via enzymatic reactions, and researchers found that the hydrophobic microdomains in peptide nanofibers contribute to the stabilization of these nanobubbles.“How to detect the formation, chemical identification and evolution of nanobubbles in this system is a big challenge. We detected in-situ the nanobubbles generated by the LOx/CAT@PNFs system and oxygen inside by taking advantage of synchrotron radiation X-ray nanoscale imaging, and then explored their dynamics using the liquid in-situ TEM.” said ZHANG Lijuan, one of corresponding authors.By regulating lactate metabolism, improving local oxygen supply, and alleviating oxidative stress, the LOx/CAT@PNFs system effectively enhances neuronal survival and improves neural function, demonstrating excellent therapeutic efficacy in both acute and chronic neurotoxic encephalopathy models.This work not only offers new insights into advancing the application of nanobubble gas delivery systems within biological organisms but also provides valuable research implications for exploring enzyme-driven gas-mediated metabolic regulation mechanisms.Construction of an efficient biomimetic enzyme complex LOx/CAT@PNFs system and the NB-synergistic metabolic regulation(Image by SARI)

Researchers Achieve 7-30 THz Continuously Tunable Strong-Field Terahertz Free-Electron Lasers

In a study published in Nature Photonics, the Free-electron Laser Team of the Shanghai Advanced Research Institute (SARI), Chinese Academy of Sciences developed an innovative approach by employing beating-frequency laser modulation of electron beams to precisely tailor the beam structure and produce continuously tunable THz radiation.

In a study published in Nature Photonics, the Free-electron Laser Team of the Shanghai Advanced Research Institute (SARI), Chinese Academy of Sciences developed an innovative approach by employing beating-frequency laser modulation of electron beams to precisely tailor the beam structure and produce continuously tunable THz radiation.Strong-field terahertz (THz) radiation with continuously tunable frequency plays a vital role in frontier scientific research such as quantum materials, molecular catalysis, and nonlinear optics, as well as in key technological fields including next-generation communications, environmental monitoring and security inspection.However, existing methods for generating strong-field THz radiation worldwide are mainly limited to the low-frequency range of 0.1–5 THz. Achieving high-intensity, continuously tunable THz radiation in the 5–30 THz frequency range has long been a critical technical challenge in this field. Free-electron lasers (FELs), as advanced light sources capable of producing continuously tunable, high-power THz radiation, offer a promising solution to this challenge. Only a few FEL facilities worldwide can currently produce continuously tunable THz radiation, and most rely on bunch-compression schemes.These approaches suffer from limited frequency tuning range and relatively low radiation pulse energy, making them inadequate for the demanding requirements of cutting-edge scientific research and industrial applications.Figure 1 SXFEL layout and the experimental schematic (Image by SARI)To overcome the challenge of generating continuously tunable strong-field THz radiation in the 5–30 THz range, researchers introduced a novel free-electron laser (FEL) approach that intrinsically covers the entire THz gap. The technique pre-modulates a relativistic electron beam with a frequency-beating laser pulse, then leverages bunch compression along with collective effects to enhance the THz microbunching.Relying on the Shanghai Soft X-ray Free-Electron Laser (SXFEL) facility in China, the research team has, for the first time, experimentally demonstrated the feasibility of this method. They successfully realized continuously tunable THz radiation covering 7–30 THz (wavelengths of approximately 10–40 μm) with the highest peak brightness ever achieved through this frequency range.Figure 2 The measured pulse energies, light spot (19 THz) and spectra (Image by SARI)The THz source delivers a pulse energy up to 400 μJ, pulse-to-pulse energy stability (RMS) better than 10%, and pulse duration tunable between 300 fs and 3 ps, with a maximum repetition rate of 50 Hz. By integrating this method with superconducting continuous-wave accelerator technology, the repetition rate could be further increased to the megahertz (MHz) level.Developing strong-field THz sources based on high-gain X-ray FEL facilities holds great potential for advancing THz pump–X-ray probe techniques. This achievement significantly extends the performance boundaries of strong-field THz sources and establishes a solid foundation for their broad applications in frontier scientific research and advanced technological developments.This research was supported by the National Natural Science Foundation of China, the SARI Innovation Fund (Fostering Program), Shanghai Municipal science and Technology Major Project, and CAS Project for Young Scientists in Basic Research.

Researchers Developed High-performance Pt Single-Atom Catalysts for Low-Temperature CO Oxidation

A research team from Shanghai Synchrotron Radiation Facility (SSRF) Science Center of Shanghai Advanced Research Institute, Chinese Academy of Sciences, have developed a high-performance catalyst by anchoring oxidized platinum single atoms on La-vacancy LaFeO₃ via a defect-engineering strategy. The catalyst delivers efficient low-temperature CO oxidation without reduction pretreatment and shows remarkable stability. The findings were published in the Journal of the American Chemical Society​.

Platinum, owing to its high catalytic activity and thermal stability, is widely used in fields such as automotive exhaust purification. Pt single-atom-sites catalysts can maximize atomic utilization while minimizing the use of precious metals. Addressing the challenges related to the activity and stability could unlock broad application prospects for these catalysts.A research team led by Dr. GAN Tao and Prof. LI Jiong from Shanghai Synchrotron Radiation Facility (SSRF) Science Center of Shanghai Advanced Research Institute, Chinese Academy of Sciences, have developed a high-performance catalyst by anchoring oxidized platinum single atoms on La-vacancy LaFeO₃ via a defect-engineering strategy. The catalyst delivers efficient low-temperature CO oxidation without reduction pretreatment and shows remarkable stability.The findings were published in the Journal of the American Chemical Society.To uncover the reaction mechanism, the team built an in situ XAFS–MS hyphenation device at the BL11B beamline of SSRF. Their study reveals that Pt single-atom-sites act as the active sites and that interfacial oxygen between v-LaFeO₃ and Pt directly participates in the reaction. CO combines with this interfacial oxygen to form CO₂, while the consumed oxygen species are rapidly replenished through O₂ dissociation around Pt sites.Although the coordination environment of Pt changes dynamically during the oxygen cycle, its oxidation state and high-coordination structure remain intact, preventing reduction, aggregation, or over-oxidation. This work provides a clear solution to the long-standing challenge of balancing activity and stability in Pt single-atom catalysts (SACs) for catalytic oxidation.Figure 1. Layout of the in situ XAFS–MS experimental setup (Image by SARI)Figure 2. Reaction mechanism analyzed by in situ XAFS–MS technique (Image by SARI)In addition, the developed XAFS–MS hyphenation technique offers a powerful tool for investigating structure–activity relationships in other catalytic processes. The in situ XAFS–MS hyphenation technique enables simultaneous capture of the structural evolution and activity changes of catalysts within the same spatial and temporal dimensions, overcoming the long-standing limitation of separating structural characterization from activity analysis in conventional studies.This approach provides a key technical foundation for in-depth investigation of structure–activity relationships in catalytic reactions.

Researchers Proposed a Direct-Amplification Enabled Harmonic Generation Free-Electron Laser

Recently, the Free-Electron Laser (FEL) team at the Shanghai Advanced Research Institute (SARI), Chinese Academy of Sciences experimentally demonstrated their independently proposed concept of Direct-Amplification Enabled Harmonic Generation Free-Electron Laser (DEHG-FEL) for the first time, and successfully achieved its lasing and stable operation.

Recently, the Free-Electron Laser (FEL) team at the Shanghai Advanced Research Institute (SARI), Chinese Academy of Sciences experimentally demonstrated their independently proposed concept of Direct-Amplification Enabled Harmonic Generation Free-Electron Laser (DEHG-FEL) for the first time, and successfully achieved its lasing and stable operation.This marks a key milestone toward realizing X-ray FEL sources operating at megahertz (MHz) repetition rates. The results were published in Physical Review Letters and were highlighted as an Editors’ Suggestion.Soft X-ray FELs with high repetition rates hold great promise in cutting-edge research areas such as time-resolved spectroscopy, coherent diffraction imaging, and ultrafast dynamics studies of nanostructures and nanodevices. However, traditional externally seeded FEL schemes typically require ultraviolet seed lasers with peak powers up to ~100 megawatts, limiting their repetition rates to the kilohertz (kHz) range.Figure1 Amplification of seed laser via high-gain FEL process while maintaining its coherence (Image by SARI)SARI’s FEL team has long been dedicated to the development of high-repetition-rate, fully coherent FELs. In previous work, they demonstrated a self-amplification mechanism of coherent energy modulation at the Shanghai Soft X-ray FEL facility (SXFEL) (Phys. Rev. Lett. 126, 084801, 2021).In the present study, by employing a long modulator section, the team directly amplified a weak seed laser through a high-gain FEL process, achieving a powerful and stable modulation laser (Figure 1).During this process, the electron beam acquired sufficient energy modulation. After passing through a dispersive section, coherent microbunching on the scale of optical wavelengths was formed, leading to the generation of fully coherent radiation up to the 12th harmonic.By further amplifying the 7th harmonic to saturation, the team achieved a pulse energy of approximately 160 µJ with an energy stability of 5.5%. Through harmonic cascading, the team successfully generated 16th harmonic output with a spectral bandwidth approaching the Fourier transform limit, indicating excellent longitudinal coherence of the DEHG-FEL (Figure 2).Figure 2 Stable, fully coherent short-wavelength FEL output achieved via harmonic conversion (Image by SARI)DEHG technology enables effective amplification of extremely weak seed laser signals with a simplified system configuration. In principle, it can reduce the required seed laser power by two to three orders of magnitude while delivering stable, controllable, high-harmonic output—making it particularly suitable for high-repetition-rate externally seeded FELs.Moreover, it has the potential to provide solutions for achieving high repetition rates in more advanced two-stage seeding schemes, such as echo-enabled harmonic generation (EEHG). In the future, DEHG could also be integrated with high-order harmonic generation (HHG) technologies to offer new tools for ultrafast spectroscopy, imaging, and materials research in the soft X-ray region.

Shanghai Synchrotron Radiation Facility Deciphers Real-Time Morphology Evolution in All-Polymer Solar Cells During Solvent Vapor "Sauna"

All-polymer solar cells (APSCs) possess excellent material flexibility, solution processability, and thermal stability, offering great potential for lightweight and large-area printed applications in wearable and stretchable devices. A critical factor in achieving high performance is the optimization of active layer morphology, especially the regulation of crystallization and phase separation of the donor. However, the real-time morphological evolution during post-treatment processes such as solvent vapor annealing (SVA) has remained unclear.To address this challenge, a research team led by Prof. YANG Chunming at the Shanghai Advanced Research Institute, Chinese Academy of Sciences established an in situ grazing-incidence X-ray scattering platform for organic solar cells at SSRF beamlines BL16B1 and BL10U1.By combining synchrotron-based grazing-incidence wide-angle X-ray scattering (GIWAXS), in situ ultraviolet-visible (UV–vis) absorption spectroscopy and grazing-incidence small-angle X-ray scattering (GISAXS), they tracked in real time the dynamic morphological changes of blade-coated PM6:PY-IT all-polymer active layers during SVA treatment.This study, for the first time, revealed a three-stage mechanism (swelling-recrystallization-rearrangement), by which SVA regulates the morphology of all-polymer blended films and its correlation with device performance (Figure 1).The related results were published in Advanced Science recently.Figure 1. (a) Schematic diagram of simultaneous in situ GIWAXS and in situ UV–vis measurements during SVA of blade-coated all-polymer solar cells,(b) Illustration of microscopic morphology evolution under different solvent vapors.In situ UV–vis spectroscopy revealed that carbon disulfide (CS2) vapor—a nonpolar solvent with high saturated vapor pressure and low solubility, induced a redshift in the PY-IT absorption peak. Conversely, chloroform (CF), a polar solvent with low saturated vapor pressure and high solubility, triggered a blueshift.This indicates that polar solvents exert a more pronounced effect on the polymer acceptor (PY-IT), driving conformational changes (blueshift) that result in a denser hole transport layer and enhanced hole transport efficiency.In situ GIWAXS analysis further confirmed three characteristic stages in the SVA process includes: solvent swelling, recrystallization, and molecular rearrangement. An appropriate SVA duration helps stabilize the crystalline structure, as evidenced by reduced lattice spacing, increased charge carrier mobility, and optimized phase separation dimensions, ultimately improving the power conversion efficiency (PCE) of the device. However, prolonged SVA can lead to re-swelling during molecular rearrangement, which is detrimental to performance.Pretreatment via thermal annealing (TA) effectively suppresses this unfavorable expansion (Figure 2). GISAXS measurements further investigated nanoscale phase separation behavior. Films subjected with combined TA and SVA of CF exhibited optimal morphology, characterized by the maximum donor coherence length (ξ), the largest acceptor aggregate radius (2Rg), and the greatest acceptor coherence length (η).The TA pretreatment induced increase in PY-IT aggregate size is key to achieving balanced crystallinity and ideal phase separation, promoting efficient charge separation and transport. This work clarified a critical mechanism: SVA with polar solvents primarily optimizes molecular packing, while SVA with nonpolar solvents tends to enhance phase separation.These insights provide a clear strategy for synergistic process-material optimization—such as combining TA with polar solvent SVA—to fabricate high-performance blade-coated devices.Furthermore, the findings lay an important foundation for future exploration of multi-solvent synergistic annealing, precise control of dynamic processes, and the development of environmentally friendly green processing, thereby accelerating the industrialization of large-area flexible APSCs.Figure 2. Evolution of d-spacing and CCL evolution of (OOP)100 peak for blade coated PM6: PY-IT blend films with a) CF, b)TA+ CF, c) CS2, and d) TA+ CS2.<!--!doctype-->