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The in situ physicochemical analysis of nanostructured functional materials is crucial for advances in their design and production. X-ray coherent diffraction imaging （CDI） methods have recently demonstrated impressive potential for characterizing such materials with a high spatial resolution and elemental sensitivity; however, moving from the current ex situ static regime to the in situ dynamic one remains a challenge. By combining soft X-ray ptychography and single-shot keyhole CDI, we performed the first in situ spatiotemporal study on an electrodeposition process in a sealed wet environment, employed for the fabrication of oxygen-reduction catalysts, which are key components for alkaline fuel cells and metal-air batteries. The results provide the first experimental demonstration of theoretically predicted Turing-Hopf electrochemical pattern formation resulting from morphochemical coupling, adding a new dimension for the in-depth in situ characterization of electrodeposition processes in space and time.

Bragg coherent X‐ray diffraction imaging (BCDI) has emerged as a powerful technique for strain imaging and morphology reconstruction of nanometre‐scale crystals. However, BCDI often suffers from angular distortions that appear during data acquisition, caused by radiation pressure, heating or imperfect scanning stages. This limits the applicability of BCDI, in particular for small crystals and high‐flux X‐ray beams. Here, we present a pre‐processing algorithm that recovers the 3D datasets from the BCDI dataset measured under the impact of large angular distortions. We systematically investigate the performance of this method for different levels of distortion and find that the algorithm recovers the correct angles for distortions up to 16.4× (1640%) the angular step size dθ = 0.004°. We also show that the angles in a continuous scan can be recovered with high accuracy. As expected, the correction provides marked improvements in the subsequent phase retrieval. An algorithm has been developed that effectively corrects and tracks angular distortions, enabling BCDI to work much more robustly and accurately in a wider range of challenging experimental scenarios.

The Coherent X‐ray Scattering beamline at the Pohang Light Source‐II was constructed in 2011 for coherent diffraction imaging and has now been upgraded in its focusing optics, diffractometer, detectors and endstation. The enhanced photon flux density and modified endstation have enabled routine Bragg coherent diffraction imaging and microbeam diffraction, while the newly implemented ptychography setup has enhanced nano‐imaging capability in transmission geometry. Because coherent diffraction imaging and microbeam diffraction share the same upstream optics, switching between techniques requires only minor adjustments to slit settings, mirror pitch and the sample‐to‐detector distance, enabling efficient integration of user programs without compromising instrument performance. This paper details the upgrade and the new capabilities of the beamline. Comprehensive upgrades to optics, detectors and the endstation at the CXS beamline have transformed its coherent diffraction imaging performance, enabling routine Bragg coherent diffraction imaging and microbeam diffraction, and adding the capability for transmission geometry nano‐imaging via ptychography.

We explore the light induced dynamics in superfluid helium nanodroplets with wide-angle scattering in a pump–probe measurement scheme. The droplets are doped with xenon atoms to facilitate the ignition of a nanoplasma through irradiation with near-infrared laser pulses. After a variable time delay of up to 800 ps, we image the subsequent dynamics using intense extreme ultraviolet pulses from the FERMI free-electron laser. The recorded scattering images exhibit complex intensity fluctuations that are categorized based on their characteristic features. Systematic simulations of wide-angle diffraction patterns are performed, which can qualitatively explain the observed features by employing model shapes with both randomly distributed as well as structured, symmetric distortions. This points to a connection between the dynamics and the positions of the dopants in the droplets. In particular, the structured fluctuations might be governed by an underlying array of quantized vortices in the superfluid droplet as has been observed in previous small-angle diffraction experiments. Our results provide a basis for further investigations of dopant–droplet interactions and associated heating mechanisms.

Bragg coherent diffraction imaging (BCDI) is a lens-less technique capable of imaging the strain in a particle in the size range from 20 nm up to several micrometres. This indirect measurement technique, used in X-ray synchrotrons or free-electron lasers all over the world, requires an inversion step using iterative algorithms in order to recover the real-space complex object encoding the particle shape and deformation field. However, artefacts such as scattering peaks called `aliens' from nearby particles can affect the accuracy of the final reconstruction and require meticulous and time-consuming manual masking of the raw data. This becomes problematic for BCDI reconstructions during an experiment and/or for large volumes of data. Here, we explore the potential of machine learning, and specifically clustering techniques, to speed up this procedure while keeping the maximum spatial resolution of the object reconstruction. We also provide a user-friendly Python Jupyter notebook program available on Github.

Crystallography is the standard for determining the atomic structure of molecules. Unfortunately, many interesting molecules, including an extensive array of biological macromolecules, do not form crystals. While ultrashort and intense X-ray pulses from free-electron lasers are promising for imaging single isolated molecules with the so-called “diffraction before destruction” technique, nanocrystals are still needed for producing sufficient scattering signal for structure retrieval as implemented in serial femtosecond crystallography. Here, we show that a femtosecond laser pulse train may be used to align an ensemble of isolated molecules to a high level transiently, such that the diffraction pattern from the highly aligned molecules resembles that of a single molecule, allowing one to retrieve its atomic structure with a coherent diffraction imaging technique. In our experiment with CO₂ molecules, a high degree of alignment is maintained for about 100 fs, and a precisely timed ultrashort relativistic electron beam from a table-top instrument is used to record the diffraction pattern within that duration. The diffraction pattern is further used to reconstruct the distribution of CO₂ molecules with atomic resolution. Our results mark a significant step toward imaging noncrystallized molecules with atomic resolution and open opportunities in the study and control of dynamics in the molecular frame that provide information inaccessible with randomly oriented molecules.

In this article we present SELUN, a novel X‐ray photon counting hybrid pixel detector developed at DECTRIS Ltd for coherent diffraction imaging techniques at synchrotron facilities. Its notable features are a pixel size of 100 µm × 100 µm arranged in a matrix of 192 × 192 elements, the possibility of use of both silicon and high‐Z sensors to guarantee high quantum efficiency across a wide range of incoming X‐ray energies, fast front‐end electronics equipped with instant retrigger technology working in non‐paralyzable counting mode, and high frame rates capability up to 120 kfps thanks to two on‐chip data‐compression mechanisms. Optimized towards speed to cope with the enhanced brilliance of fourth‐generation synchrotron sources, it shows remarkable count rate saturation values ranging from about 30 to 60 Mcts s−1 pixel−1, depending on the sensor material and value of the incoming X‐ray energy, and energy‐resolution figures of 664 eV r.m.s. for a silicon sensor and 1.22 keV r.m.s. for a cadmium zinc telluride (CZT) sensor. Here, we present SELUN, a novel X‐ray photon counting hybrid pixel detector developed at DECTRIS Ltd for coherent diffraction imaging techniques at synchrotron facilities.

A Nanobeam X‐ray Experiments (NXE) instrument was developed and installed at the hard X‐ray beamline of the Pohang Accelerator Laboratory X‐ray Free Electron Laser. This instrument consists of a diagnostic system, focusing optics, an X‐ray diffraction endstation and a femtosecond laser delivery system. The NXE instrument enables sophisticated X‐ray experiments using nanofocused X‐rays. At a 9.5 keV X‐ray energy, the beam was successfully focused to 390 nm × 230 nm at the focal plane using Kirkpatrick–Baez mirrors. Following the successful commissioning experiments in December 2021 and April 2022, the instrument became available for regular user experiments in January 2023. The first user experiment was conducted in January 2024. This article provides detailed information on the beamline optics, the NXE instrument, and its performance and capabilities. The Nanobeam X‐ray Experiments (NXE) instrument at the Pohang Accelerator Laboratory X‐ray Free Electron Laser (PAL‐XFEL) is introduced. The NXE instrument enables users to conduct X‐ray experiments with nanofocused X‐rays.

Ptychographic coherent diffraction imaging (PCDI) is a synchrotron X-ray microscopy technique that provides high spatial resolution and a wide field of view. To improve the performance of PCDI, the performance of the synchrotron radiation source and imaging detector should be improved. In this study, ptychographic diffraction pattern measurements using the CITIUS high-speed X-ray image detector and the corresponding image reconstruction are reported. X-rays with an energy of 6.5 keV were focused by total reflection focusing mirrors, and a flux of ∼2.6 × 10 10  photons s −1 was obtained at the sample plane. Diffraction intensity data were collected at up to ∼250 Mcounts s −1 pixel −1 without saturation of the detector. Measurements of tantalum test charts and silica particles and the reconstruction of phase images were performed. A resolution of ∼10 nm and a phase sensitivity of ∼0.01 rad were obtained. The CITIUS detector can be applied to the PCDI observation of various samples using low-emittance synchrotron radiation sources and to the stability evaluation of light sources.