Gung-Chian Yin

Following our initial demonstration of ptychography at the Taiwan Photon Source (TPS), the system has been substantially upgraded. This article details the design and performance of the new hard X-ray 2D ptychography endstation, TPS 25A2. A zone-plate focusing system has been inserted downstream of the previous Kirkpatrick–Baez mirror optics at the TPS 25A2 beamline. Operating at a photon energy of 8.979 keV, the endstation routinely achieves a spatial resolution of sub-10 nm in 2D, with a highest achieved resolution of 6.9 nm on a standard Siemens star test pattern. We present the full instrumental specifications and performance benchmarks, and showcase the endstation's capabilities with imaging examples of inorganic nanoparticles and a complex biological structure. The establishment of TPS 25A2 provides the scientific community with a powerful and accessible tool for nanoscale imaging.

In this work, we developed a vacuum-compatible long trace profiler (LTP) for in situ metrology of ultra-precise x-ray optics within synchrotron vacuum chambers. Although traditional LTPs operate ex situ under atmospheric pressure, earlier optical setups—such as that by Qian et al.—performed in situ distortion measurements by directing laser beams through vacuum viewports. While these configurations enabled in situ monitoring of mirror deformation, their accuracy was constrained by optical distortions from vacuum windows and by beam deviations caused by air turbulence. To overcome these limitations, we developed a fully in-vacuum LTP system installed directly inside the vacuum chamber, fully compatible with ultrahigh vacuum (UHV) conditions (<1 × 10−8 Torr). Based on the original Takacs LTP design, the system incorporates a vacuum-compatible CMOS sensor, an external laser to reduce heat and weight, and a motorized four-axis alignment stage. This system is designed to measure low-spatial-frequency slope error, which is critical for evaluating optical figure quality. Performance was validated under identical atmospheric conditions using a conventional LTP for comparison. Under identical conditions, the in-vacuum LTP measured slope errors of 100 nrad RMS (flat) and 200 nrad RMS (curved). However, measurable deviations in curvature radius and coma coefficient were observed, attributed to stage wobble and lens aberrations. These findings confirm baseline performance and demonstrate the system’s feasibility for UHV-compatible slope metrology. The in-vacuum LTP is intended to support real-time slope monitoring and feedback correction of active optical components during operation at synchrotron beamlines.

The TPS Phase III soft x-ray beamlines, designated as 33, 35, and 43, employ bendable mirrors to achieve the required optical performance across a broad energy range. All mirrors, except for the grating mirrors, are designed with adjustable height and position to optimize alignment. The mirrors are secured to the bending mechanism using specially designed clips and bolt joints. During bending, the mirror surface deformation can be approximated by second- and third-order polynomial terms, which must be removed to minimize optical aberrations. After applying these corrections, the residual slope error in the useful optical area must remain below ±1.5 × 10−6 rad to meet performance criteria. Therefore, the design of the mirror clip and the precise application of bolt joint forces are critical to achieving high-accuracy figure control. This study systematically investigates how varying bolt joint forces at the mirror clip can compensate for high-order residual deformations. Finite element method simulations were conducted to determine optimal force distributions, providing guidance for experimental setup and safe mounting conditions. In experiments, the bolt joint forces were adjusted using a calibrated torque wrench, while the long trace profiler continuously measured the slope error to identify the configuration yielding the widest functional optical area with minimal residual error.

In this article, we discuss the key issues related to the design and construction of the Transmission X-ray Microscopy (TXM) endstation. We address the major challenges encountered, particularly those related to vibration during the assembly and alignment of optical components. Another significant focus is the wobble observed in the rotary stage and the misalignment between various stages of the TXM endstation. We evaluate the impact of these issues on overall performance and describe the measures implemented to mitigate them, ensuring precision and stability during experiments.

Characterizing the microstructure of all-solid-state batteries (ASSBs) during fabrication and operation is vital for their advancement, particularly as scaling to pouch-cell levels introduces challenges in probing large-scale microstructural evolution. This work highlights the potential of synchrotron X-ray micro-computed tomography (sXCT) as a non-destructive, rapid (<30 minutes), and high-resolution technique for visualizing and quantifying key microstructural features, including overhang, porosity, contact loss, active surface area, and tortuosity, in all-solid-state pouch cells. The large field of view (up to millimeters) of sXCT enables detailed analysis at an industry-relevant scale, bridging the gap between laboratory research and commercial applications. Furthermore, integrating realistic sXCT-derived 3D models into multiphysics simulations could provide novel insights into chemo-mechanical degradation, particularly at the edges of the pouch cells, offering a pathway for designing robust, high-performance ASSBs. This perspective establishes sXCT as an indispensable tool for advancing both the understanding and engineering of next-generation energy storage systems.

Pulsed-laser deposition was utilized to fabricate Eu-doped ZnO epitaxial films on c-plane sapphire substrates with Eu concentrations ranging from 0.5 to 4.0 at. %. The structural properties were analyzed using x-ray diffraction surface normal radial scans and azimuthal cone scans, which confirmed the epitaxy of the film samples. Reciprocal space mapping was performed on ZnO(101̄1) to visualize the effect of Eu incorporation. X-ray fluorescence mapping confirmed the homogeneous distribution of Zn and Eu, and x-ray absorption near-edge structure spectra directly confirmed the trivalent state of Eu ions. The optical properties were assessed using temperature-dependent photoluminescence (PL). Various defects were identified. With increasing Eu dopant concentration, PL emissions from defects and the Eu 4f-intraband transitions gradually became the predominant features in the PL spectra at low temperatures. Furthermore, PL analysis suggested that Eu ions substituted Zn, occupying sites with lower C3v symmetry due to the distortion caused by Eu incorporation.

Distributions of Eu2+ and Eu3+ do affect the optical properties. However, the substitution of the activator ions hardly perturbed the crystal structure of the host lattice. Without the differences in crystal structure, it is not trivial to develop an effective descriptor to investigate stoichiometry-dependent mechanism to explore the effects of Eu species on valence states. In this study, through x-ray nanodiffraction, x-ray fluorescence, x-ray absorption near edge structure, and x-ray excited optical luminescence, we mapped the valence state distributions of Eu species to calculate the local mixing enthalpy and entropy. The calculated thermodynamics parameters show good agreement with the optical properties. We found that Eu2+ of Eu-doped BaAl2O4 predominantly existed in a divalent state, which results in segregation phenomena of local Eu2+ and Eu3+ ions.

In this study, a combination of X-ray excited optical luminescence (XEOL), time-resolved XEOL (TR-XEOL) and the Hanbury-Brown and Twiss (HB-T) interferometer at the Taiwan Photon Source (TPS) 23A X-ray nanoprobe beamline for exploring quantum materials is demonstrated. On the basis of the excellent spatial resolution rendered using a nano-focused beam, emission distributions of artificial micro-diamonds can be obtained by XEOL maps, and featured emission peaks of a selected local area can be obtained by XEOL spectra. The hybrid bunch mode of the TPS not only provides a sufficiently high peak power density for experiments at each beamline but also permits high-quality temporal domain (∼200 ns) measurements for investigating luminescence dynamics. From TR-XEOL measurements, the decay lifetime of micro-diamonds is determined to be approximately 16 ns. Furthermore, the XEOL spectra of artificial micro-diamonds can be investigated by the HB-T interferometer to identify properties of single-photon sources. The unprecedented strategy of combining XEOL, TR-XEOL and the HB-T interferometer at the X-ray nanoprobe beamline will open new avenues with significant characterization abilities for unraveling the emission mechanisms of single-photon sources for quantum materials.

TPS 31A fast tomography and energy-resolved elemental mapping projection X-ray microscopy (PXM) and transmission X-ray microscopy (TXM) beamline of NSRRC is under construction and commissioning. This beamline will provide four operating modes including (1) PXM with white light mode, (2) PXM with double multilayer monochromator (DMM) mode, (3) PXM with double crystal monochromator (DCM) mode, and (4) TXM with double crystal monochromator (DCM) mode. All modes are capable of absorption contrast and phase contrast of images. The spatial resolution of three PXM modes is 0.5 µm. The field of view of PXM-white light, PXM-DMM, and PXM-DCM mode is 25×18 cm², 25×10 mm² and 25×3 mm², respectively. The temporal resolution of PXM modes can approach 1ms/frame and 45 sec/tomography. The in operando tomography and energy-resolved elemental mapping within 2D image as well as tomography are feasible. The spatial resolution and field of view of TXM mode is expected as 30 nm and 30 µm, respectively. The energy-resolved elemental mapping within 2D image and tomography is practical.