When high-energy electrons travelling near the speed of light are made to move along a circular path, they emit a strong electromagnetic radiation, or light, called synchrotron radiation. The wavelength of synchrotron radiation is typically around a tenth of a nanometre (a nanometre is one billionth of a metre), and is comparable to interatomic distances, which makes it ideal for the study of atoms and bonds within materials and molecules. This is the reason why synchrotron radiation sources are often compared to giant microscopes.

Japan’s synchrotron radiation facility SPring-8 is a high-bright­ness source of X-rays covering a very broad range of wavelengths. At the core of the facility is the storage ring, which circulates high-energy electrons around a 1.4-kilometer path. The X-rays are extracted into a series of beamlines equipped with instruments for a wide range of analyses.

The intense X-ray beams produced by the facility are particularly suitable for determining crystal structures at ultrahigh resolution, and for this reason the SPring-8’s beamlines are in high demand among researchers in both structural biology and materials science.

SPring-8 remains the largest third-generation syn­chrotron in the world, and thanks to ongoing joint development by the Japan Synchrotron Radiation Research Institute (JASRI) and RIKEN, continues to maintain its world-leading status.

The BL12B2 beamline is part of the Taiwan X-ray facilities at SPring-8. It is designed to provide atomic-resolution structural probing environment for biostructure and materials researches. Combining various configurations of the beamline optical components, the users can operate the beamline in either white mode, or monochromatic mode with X-ray energies from 5 to 70 keV and an energy resolution ΔE/E ∼ 10-4. Four experimental stations are attached to the beamline, including X-ray Absorption Spectroscopy (XAS), powder X-ray diffraction (PXD), X-ray scattering (XRS) and protein crystallography (PX).

Image from RIKEN & SPring-8

Structure and structural kinetics of materials is always the attractive and fundamental issues for scientific research. A high resolution, high acquisition speed and high throughput powder X-ray diffraction beamline, 19A, is designed to investigate the molecular structures at diverse sample environments.

TPS 27A beamline is powered by an elliptically polarized undulator (EPU) with magnets at a 66 mm period length, and photons are monochromized by active gratings to cover an energy window of 90 to 2200 eV at a resolving power of 10,000. The beamline is to host two microscopes in separated branches.

At the first branch, it sits a zone-plate-based scanning transmission X-ray microscope (STXM) developed jointly with Prof. Way-faung Peng at Tamkang University.  The STXM is capable of recording absorption-based images as well as coherent diffraction images (ptychography).

With the capabilities described above, the Nanoscopy beamline is expected to attract a broad range of domestic and international users whose expertise includes environment, energy, polymer, magnetism, semiconductor, and low-dimensional physics and chemistry.

A new tender X-ray absorption spectroscopy beamline (TPS 32A) has brought high-brightness beam performance using the bending magnet (BM). The back-to-back water-cooled double crystals monochromators (DCMs, Si (111) and InSb (111)) can cover the unique photon energy range from 1.7 to 11 keV (often called “tender X-ray” and somewhat higher). The simulated focus beam size is 0.6 × 0.3 mm2 (h × v, FWHM) via the Si(111) DCM at 4keV with the photon flux is ~1012 phs/s. This photon energy range covers the K-edges of elements from Si to Zn, L-edges of the second-row transition metals (4d elements) and the lanthanides (4f elements), and the M-edge of part of 5d elements. The spectroscopies experiments on this beamline will provide information on the electronic and atomic structure of the scientific applications.

TPS 32A beamline is suitable for application to various scientific fields, including physics, chemistry, materials science, chemical engineering, geology, earth, biology, and environmental sciences. The X-ray absorption spectroscopy (XAS) technique is routinely employed to probe the electronic and atomic structures of specific elements in materials. The detection limit of the multi-sensor fluorescence silicon drift detector (SDD) may reach around monolayer (a few ppm) levels. On the other hand, configured hard X-ray photoelectron spectroscopy (HAXPES) technique using a high-quality electron energy analyzer can probe properties in deeper layers of the samples and access core-level electrons. Micro-XAS will also be available with ~5 μm spatial resolution in the endstation. Various furnaces, cryostats, and in-situ cells for different sample environments will be available on request. All the efforts are to provide diversified and user-friendly experimental conditions and environments to maximize the scientific output.

Quick-scanning X-ray absorption spectroscopy beamline using bending magnet at Taiwan Photon Source (TPS) was newly constructed for the studies of Physics, Chemistry, Biology, Environmental and Arts. This beamline provides the capability of the fast scanning and step-by-step scanning for in situ time-resolved measurements and conventional XAS experiments respectively. The acquired time for a full quick-scanning EXAFS spectrum is less than 100 milliseconds over 1000 eV. The short lived intermediate states in chemical reaction such as charge/discharge process and catalytic process can be observed by using in situ time-resolved measurements. Additionally, the beam spot can be focused down to 5 by 5 micrometer by a set of KB-mirrors to provide the capability of microprobe analysis. The element or valence distribution can be well probing by fluorescence image mapping.

This beamline is a high resolution DCM X-ray beamline with both collimating and focusing mirrors, which will deliver monochromatic photon beams with energy ranging from 6 keV to 33 keV for Extended X-ray Absorption Fine Structure (EXAFS), powder diffraction and the related experiments. At the sample position, the expected photon flux is 1 × 1011 photon/sec /200mA with an average energy resolution (ΔE/E) of 1.6 × 10-4 and the focused beam size is about 0.9 mm × 0.2 mm.

The DCM tender X-ray beamline is a bend-magnet soft X-ray beamline, which provides good monochromatized photon beams with energies from 1 up to 8 keV that covers the K edges of elements from Na to Cr and L edges of the first and second rows of transition metals. This beamline provides good opportunity to study some important materials such as zeolites, catalysis, and etc. This beamline takes the leftmost 6 mrads of the horizontal radiation from the BL16 port. After the front-end, the photon beam passes through a graphite filter and slit aperture, and is then vertically collimated by a water-cooled Silicon mirror (Coating: 800Å (±10%) Nickel) located at 5.7 m. The collimated beam is then dispersed by a double crystal monochromator (DCM) at 9 m. The monochromatized beam is then focused by a bent toroidal glidcop mirror at 11.7 m and reaches the sample position at 18.20 m. This beamline delivers soft X-ray beams from 1 to 8 keV with energy resolving power of up to 7000.

Three wiggler X-ray beamlines have been specially designed to share the total 13 mrad of the horizontal radiation from the 25-pole 1.8-tesla wiggler insertion device located at beam port 17. These beamlines take 3, 4, 3 mrads of horizontal radiation, respectively. There is only 1.5 mrad separation left between each two adjacent beamlines for all the hardware mechanism assemblies.

The 17C wiggler beamline, which accepts the leftmost 3 mrad of the wiggler radiation, is designed to cover a wide photon spectrum ranging from 4.5 to 13 keV with a resolving power of up to 7000 for X-ray spectroscopy experiments. The whole beamline is an UHV design. Along the beamline, there is one graphite filter set at 11 m, one water-cooled collimating mirror at 12.3 m, one Si(111) double crystal monochromator (C-mono) at 16.9 m, one water-cooled bent toroidal refocusing mirror at 20.5 m, one high-order harmonic light rejection mirror at 27 m, and the sample position is at 30 m from the center of the wiggler device. A good focused white-light beam is available from this beamline.

The WR-SGM beamline is based on the Dragon type, six-meter spherical grating monochromator (SGM) design, and supports two endstations with photons delivered over a wide spectral range from 15 to 1600 eV by using a total of six gratings. Two movable entrance slits in conjunction with a common movable exit slit are employed to provide two different grating included angles of 160° and 174° required for low energy and high energy branches, respectively.

The first optic element, a bendable HFM located at 5.5 m from the source, collects 11 mrad. of the horizontal fan of bending magnet radiation and focuses the photon beam horizontally at either after the exit slit or after re-focusing mirror (RFM). Two cylindrical VFMs, one for low-energy branch and the other for high-energy branch, are employed to provide two different optical paths. The photon beam of the low-energy branch is focused vertically and deflected upwards by the VFML and then reflected downwards by a plane mirror. A common movable exit slit is used for both branches. A single toroidal RFM is used to focus the beams onto the sample (22.6 m from the source). The final focused image at the sample position is about 0.7 × 0.3 mm (FWHM).

The switching of the optical path between high and low energy branches is straightforward, thanks to the precision pre-alignment of the mechanical and optics components. The switching requires only a simple vertical translation of the VFMs followed by a minute readjustment of the pitch angle of VFM done with a piezoelectric translator. The horizontal focus of the beamline can be positioned between two endstations by utilizing bendable feature of HFM; however, this bendable feature has rarely been used due to a concern of structural fatigue of the bender.

Two end-stations are positioned in the beamline. A traditional photoelectron spectroscopy (PES) endstation is located after the exit slit (S2), and the second endstation dedicated to novel ambient pressure X-ray photoelectron spectroscopy (APXPS) is located at the beamline focus after the RFM.