Shanghai Synchrotron Radiation Facility Research Articles

Direct Work Function Measurement Using In-situ APXPS and Its Application on Copper Oxidation Process.

The work function (WF) measurement plays a critical role in engineering energy materials and energy devices. However, the ultra-high vacuum (UHV) environments of photoemission method limit the practical application for absolute work function measurements of materials, especially under complex working conditions. To understand the energy level of materials under complex chemical environments, the in-situ measurements of work function is necessary in complex metal/semiconductor system for various application. In this paper, we describe the utilization of ambient pressure X-ray photoemission spectroscopy (APXPS) with utilization of low photon energy X-ray for absolute WF measurements at BL02B of the Shanghai Synchrotron Radiation Facility. We herein present the WF measurement during oxygen adsorption on Pt(111) and oxidation of Cu(111) in ambient oxygen environment as demonstration of the APXPS capability for WF measurement. After oxygen chemisorption on Pt and formation of Cu2O, the WF will increase. This is due to charge transfer from metal to chemisorbed oxygen atoms. After the formation of bulk Cu2O and CuO, the WF value almost remain at ~5.5 eV. We believe the direct measurement of absolute work function via APXPS could help bridge the gap between the physical properties and the surface chemical species for metal/semiconductor materials.

X-ray storage tracks characteristics for Ag-doped phosphate glass based on radio-photoluminescence

Ag-doped phosphate glass (Ag-PG) is an excellent X-ray image storage material applied for recording X-ray tracks. In this work, we used Geant4 software to simulate the energy deposition attenuation and 2D/3D storage tracks characteristics of Ag-PG. The influence of the secondary particles generated by the interaction between X-rays and Ag-PG was analyzed. The storage cutoff depth of Ag-PG was verified at the Shanghai Synchrotron Radiation Facility (SSRF). The results show that the optical transmittance is slightly decreased after X-ray irradiation. The cutoff depth is only 200 μm for complete absorption, when the X-ray energy is 5 keV. The deposited energy is attenuated by 19.8% at the depth of 900 μm, when the X-ray energy is 30 keV. The distribution of deposited energy is primarily influenced by the attenuation of secondary electrons generated by the interaction between X-rays and Ag-PG. Furthermore, the 2D/3D models show that the storage depth is not significantly affected by different doses at the same X-ray energy. The low diffusion of the tracks spread plays a crucial role in achieving high spatial resolution. The storage cutoff depth in Ag-PG is approximately 10 mm at 20 keV. This has been successfully verified by SSRF, and it holds great significance for high-resolution imaging and quantitative storage of X-ray images in Ag-PG.

Preparation and measurement of an x-ray Laue-type monochromator based on a WSi2/Si multilayer

The Laue-type multilayer monochromator (LMM) is a promising optical element with a small size and high efficiency in a synchrotron radiation facility. By the dynamical diffraction theory, using DC magnetron sputtering technology, an LMM with a total thickness of 47 µm and a periodic thickness of 4.7 nm WSi2/Si multilayer at 26 keV is designed and fabricated. During the preparation, the total number of layers is up to 20000, and every 300th layer of Si is replaced by WSi2 as the marker, so the multilayer is divided into 67 areas. The cross section of the multilayer is measured by a scanning electron microscope (SEM), and the marker region thickness error is 0.28% (RMS). The diffraction test experiment of the LMM is carried out at the Shanghai synchrotron radiation facility (SSRF). The 1st-order peak angle is 5.05 mrad, and the efficiency is 75.0%, which is close to the theoretical calculation result of 5.1 mrad and 79.1%. The Darwin width of the LMM is 0.17 mrad which is equal to the theoretical calculation. Based on the Bragg’s diffraction equation, the energy resolution (ΔE/E) is 3.3%.

Upgrade of crystallography beamline BL19U1 at the Shanghai Synchrotron Radiation Facility

BL19U1, an energy-tunable protein complex crystallography beamline at the Shanghai Synchrotron Radiation Facility, has emerged as one of the most productive MX beamlines since opening to the public in July 2015. As of October 2023, it has contributed to over 2000 protein structures deposited in the Protein Data Bank (PDB), resulting in the publication of more than 1000 scientific papers. In response to increasing interest in structure-based drug design utilizing X-ray crystallography for fragment library screening, enhancements have been implemented in both hardware and data collection systems on the beamline to optimize efficiency. Hardware upgrades include the transition from MD2 to MD2S for the diffractometer, alongside the installation of a humidity controller featuring a rapid nozzle exchanger. This allows users to opt for either low-temperature or room-temperature data collection modes. The control system has been upgraded from Blu-Ice to MXCuBE3, which supports website-mode data collection, providing enhanced compatibility and easy expansion with new features. An automated data processing pipeline has also been developed to offer users real-time feedback on data quality.

A new experimental station for microbeam X-ray scattering at the SSRF BL10U1 beamline

Benefiting from the development of high-brilliance synchrotron radiation sources, microbeam X-ray scattering has become a well established scattering-based imaging technology. This article describes the newly constructed time-resolved microbeam small-angle X-ray scattering (µSAXS) experimental station at the BL10U1 beamline at the Shanghai Synchrotron Radiation Facility. The µSAXS endstation provides SAXS/WAXS measurements with a 10 µm hard X-ray beam and a flux of ∼1012 photons s−1. A multi-axis sample stage, an on-axis viewer and in situ experimental apparatus are incorporated to facilitate multi-method scientific experiments in various material fields. As scientific examples, this article explores 1D tomography, 2D mapping and tomographic sectioning based on X-ray scattering to investigate the micro–nanostructures of polymer fiber, spherulite and bamboo samples.

Multilayer Kirkpatrick-Baez focusing mirrors with phase compensation for sub-20 nm focusing at the hard X-ray nanoprobe beamline of SSRF

The hard X-ray nanoprobe beamline is the first beamline to take advantage of the full coherent beam to attain the nanoscale focusing at the Shanghai Synchrotron Radiation Facility (SSRF). Here we introduce the beamline and specially go over the features of the multilayer Kirkpatrick-Baez focusing system and its supporting phase compensator system. The performance and stability of the phase compensator are also put to the test. By using the speckle scanning metrology, the wavefront of a focused beam was characterized and intensity distribution near the focus was reconstructed. The focusing performance was greatly enhanced by two phase compensations based on a global optimization technique, and a two-dimensional focal spot of 26 nm × 17 nm was achieved and maintained with good stability.

Research and optimization of flow-induced vibrations in a water-cooled monochromator.

To enhance the stability of the water-cooled double-crystal monochromator used at the BL17B beamline of the Shanghai Synchrotron Radiation Facility (SSRF), a study was conducted to optimize its cooling system's flow-induced vibration. Through simulation and experimental verification, the researchers analyzed the vibration mechanism and implemented improvement measures. The results indicate that the elastic bellows greatly amplify flow-induced vibration, transmitting it to the first-crystal. By positioning the bellows closer to the crystal, the relative pitch angular vibration of the double-crystal was reduced by 17.5%, and the roll angular vibration decreased by 6.1%. Furthermore, changing the flow rate from 3 to 2.4 l/min further diminished the relative pitch angular vibration by 6.0% and the roll angular vibration by 7.9%. By effectively reducing flow-induced vibration in the water-cooled double-crystal monochromator, equipment stability is enhanced, and the relative angular vibration of the double-crystal has been reduced. This research provides a valuable method and approach for optimizing the stability of the monochromator and related equipment.

Crystallographic Data Collection Using a Multilayer Monochromator on an Undulator Beamline at the Shanghai Synchrotron Radiation Facility

To resolve photons hungry for weak diffraction samples by the crystallographic method, a double-multilayer monochromator (DMM) was employed on an undulator beamline (BL17UM) at the Shanghai Synchrotron Radiation Facility (SSRF) to provide a focused sub-micron beam with high brightness for macromolecular crystallography experiments. High-quality crystallographic datasets from model protein crystal samples were collected and processed by an existing crystallographic program for structure solution and refinement. The data quality was compared with datasets from a normal silicon crystal monochromator to evaluate the bandwidth of the DMM effect on these crystallographic data. This experiment demonstrates that multilayer optics on an undulator beamline may play a valuable role in satisfying the demands of structure-related research, which requires novel methods.

Finback: a web-based data collection system at SSRF biological macromolecular crystallography beamlines.

An integrated computer software system for macromolecular crystallography (MX) data collection at the BL02U1 and BL10U2 beamlines of the Shanghai Synchrotron Radiation Facility is described. The system, Finback, implements a set of features designed for the automated MX beamlines, and is marked with auser-friendly web-based graphical user interface (GUI) for interactive data collection. The Finback client GUI can run on modern browsers and has been developed using several modern web technologies including WebSocket, WebGL, WebWorker and WebAssembly. Finback supports multiple concurrent sessions, so on-site and remote users can access the beamline simultaneously. Finback also cooperates with the deployed experimental data and information management system, the relevant experimental parameters and results are automatically deposited to a database.

Orbit stabilization for the new insertion devices in SSRF

During the Shanghai Synchrotron Radiation Facility (SSRF) beamline project, fourteen new insertion devices (IDs) have been successfully installed and transitioned to operation. However, these new IDs led to considerable closed orbit distortions in the SSRF storage ring. In the canted beamlines, the theoretical current values of dipoles required for the closed dual-canted angle were established, however, errors in the actual machine make a significant effect on closed orbit. To address this, an adjustment configuration, based on the response matrix, was developed for the closed dual-canted angles. Additionally, an orbit feedforward compensation system equipped with corrector coils, was employed. As a result, the maximum horizontal and vertical orbit distortions induced by the IDs were successfully decreased to less than 5.0 μm and 3.5 μm, respectively. Furthermore, a specialized local fast feedback system was designed to maintain the precise orbit and angle stability for the Hard X-ray Nanoprobe beamline.

Millisecond dynamics of colloidal suspension studied by X-ray photon correlation spectroscopy at the Shanghai Synchrotron Radiation Facility

Millisecond dynamics of colloidal suspension studied by X-ray photon correlation spectroscopy at the Shanghai Synchrotron Radiation Facility

Comparative Investigation of the Microstructure of MgCl2 Aqueous Solutions Using Different X-ray Scattering Sources, Raman Spectroscopy, and Atomistic Simulations.

Aqueous solutions of magnesium chloride (MgCl2(aq)) are often used to test advances in the theory of electrolyte solutions because they are considered an ideal strong 2:1 electrolyte. However, there is evidence that some ion association occurs in these solutions, even at low concentrations. Even a small ion-pairing constant can have a significant impact on the chemical speciation of ions, so it is important to determine whether ion pairing actually occurs. In this study, MgCl2(aq) with concentrations ranging from 1 to 35% was studied using three methods: X-ray scattering (XRS) with the Shanghai Synchrotron Radiation Facility (SSRF) and silver-anode laboratory sources, Raman spectroscopy, and molecular dynamics (MD) simulations with the COMPASS-II and Madrid force fields. XRS results were analyzed in the framework of PDF theory to obtain the reduced structure function F(Q) and the reduced pair distribution function G(r). The F(Q) values from synchrotron radiation and laboratory sources both showed that the tetrahedral hydrogen bonds in bulk water were destroyed with the increased MgCl2 concentration. The results of G(r) indicated that the main peaks centered at 2.05 and 2.80 Å can be ascribed to the interactions of Mg-O and O-O, respectively. The peak at 3.10 Å is attributed to the combined effect of O-O and Cl-O. By comparing the structural information on MgCl2 solution obtained from the two light sources, it was found that both SSRF and silver-anode laboratory sources can reflect the above-mentioned structural information on MgCl2 solution. The radial distribution function (RDF) obtained from MD simulations of MgCl2 solutions assigned the peaks at 2.0, 2.8, and 3.2 Å to the Mg-O, O-O, and Cl-O interatomic pairs, respectively. The decrease in the O-O coordination number confirms that the hydrogen-bonding network of water is disrupted by increasing MgCl2 observed by X-ray scattering. The proportion of Mg-Cl contact ion pairs gradually increases with MgCl2 concentration as does the coordination number. Raman spectroscopy results show that the bond type changes from double donor double acceptor (DDAA) to single donor-single acceptor (DA) with increasing concentration, providing explicit details of the hydrogen-bond evolution in the aqueous solution.

Latest developments in EUV photoresist evaluation capability at Shanghai Synchrotron Radiation Facility

Latest developments in EUV photoresist evaluation capability at Shanghai Synchrotron Radiation Facility

BL02U1: the relocated macromolecular crystallography beamline at the Shanghai Synchrotron Radiation Facility

BL02U1: the relocated macromolecular crystallography beamline at the Shanghai Synchrotron Radiation Facility

In situ label-free X-ray imaging for visualizing the localization of nanomedicines and subcellular architecture in intact single cells.

Understanding the intracellular behaviors of nanomedicines and morphology variation of subcellular architecture impacted by nanomaterial-biology (nano-bio) interactions could help guide the safe-by-design, manufacturing and evaluation of nanomedicines for clinical translation. The in situ and label-free analysis of nano-bio interactions in intact single cells at nanoscale remains challenging. We developed an approach based on X-ray microscopy to directly visualize the 2D or 3D intracellular distribution without labeling at nanometer resolution and analyze the chemical transformation of nanomedicines in situ. Here, we describe an optimized workflow for cell sample preparation, beamline selection, data acquisition and analysis. With several model bionanomaterials as examples, we analyze the localization of nanomedicines in various primary blood cells, macrophages, dendritic cells, monocytes and cancer cells, as well as the morphology of some organelles with soft and hard X-rays. Our protocol has been successfully implemented at three beamline facilities: 4W1A of Beijing Synchrotron Radiation Facility, BL08U1A of Shanghai Synchrotron Radiation Facility and BL07W of the National Synchrotron Radiation Laboratory. This protocol can be completed in ~2-5 d, depending on the cell types, their incubation times with nanomaterials and the selected X-ray beamline. The protocol enables the in situ analysis of the varieties of metal-containing nanomaterials, visualization of intracellular endocytosis, distribution and excretion and corresponding subcellular morphological variation influenced by nanomedicines in cell lines or primary cells by using this universal and robust platform. The results facilitate the understanding of the true principle and mechanism underlying the nano-bio interaction.

In-house design hard X-ray transmission microscope at SSRF

A hard X-ray full field transmission X-ray microscopy (TXM) based on zone plate optics has been constructed at BL18B beamline at Shanghai Synchrotron Radiation Facility (SSRF). This beamline aims to the frontier science issues demands in many fields including nanomaterials, energy and life sciences, providing advanced nanostructure characterization for submicron-sized samples. It uses a bending-magnet source and works in the range of energies from 5 keV to 14 keV. The achieved spatial resolution of TXM imaging is 20 nm. This paper describes the details of the design, characterization, stability testing, TXM, CT and 2D TXM-XANES performance of this beamline.

Simulation of Beamline Motion Control System of Shanghai Synchrotron Radiation Facility BL13U

The Shanghai Synchrotron Radiation Facility’s hard X-ray nanoprobe wire station is currently under construction, so it is unable to conduct research on online testing, however, beamline adjustment is crucial prior to conducting experiments at the wire station, this challenge can be more effectively addressed by using simulation testing instead of online testing. In order to carry out intelligent beamline adjusting research before the online station is completed, this paper designs a beamline adjusting test simulation platform based on the EPICS software. Through the software simulation of the motor control system of the above-mentioned beamline, the beamline adjusting application of intelligent control methods is realized. The test results show that the system runs well and the intelligent beamline adjusting algorithm can efficiently and automatically optimize the motors in the system. The beamline adjusting test platform based on EPICS software can be further applied to the simulation and testing of other beamlines at the Shanghai Synchrotron Radiation Facility.

A machine-learning based closed orbit feedback for a synchrotron light source

In order to improve the stability of synchrotron radiation, we developed a new method of machine learning-based closed orbit feedback, and piloted it in the storage ring of the Shanghai Synchrotron Radiation Facility (SSRF). In our experiments, the machine learning-based closed orbit feedback can carry out horizontal, vertical and RF main frequency feedback simultaneously. What's more, the residual values of variations in the correctors' currents before vs. after correction can be almost ignored. This machine learning-based new method is expected to establish a new closed orbit feedback system and improve the orbit stability of the storage ring in daily operation.

Modeling of intrinsic photon-stimulated desorption yields under readsorption effect

In synchrotron radiation and electron storage rings, photon-stimulated gas desorption is a major contributor to gas load, leading to vacuum degradation and compromising the stability and quality of the beamline. Therefore, it is imperative to investigate the underlying mechanisms of photon-stimulated gas desorption to enhance the reliability of the experiments. In this paper, a theoretical model for analyzing the process of photon-stimulated desorption is presented, and the equations are solved numerically by considering the evacuation, bulk diffusion, thermal outgassing, adsorption, and desorption of surface gas molecules. The modified model can predict the yield of H2 gas desorption induced by photon stimulation when synchrotron radiation is directed vertically onto various sample surfaces, utilizing the coupled multi-physics solution. The calculated results are consistent with the experimental measurements obtained from the Shanghai Synchrotron Radiation Facility. The results show that the photodesorption yield is related to the amount of surface-adsorbed molecules, which explains the observed decrease in the photodesorption yield with increasing accumulated photon dose. Furthermore, the study provides a theoretical approach to predicting the pressure evolution of photon-stimulated desorption.

Development of an APPLE III undulator prototype with three-dimensional force compensation for SHINE

The Shanghai high-repetition-rate XFEL and extreme light facility (SHINE) plans to install several elliptically polarizing undulators (EPUs) as afterburners behind the planar undulator section to obtain nearly saturated circularly polarized free-electron laser (FEL) radiation. Therefore, the SHINE R&D project needs to develop a 4-m-long EPU with an effective magnetic field of 1.5 T, a period of 68 mm, and a minimum gap of 3 mm. A magnetic force compensation EPU prototype has recently been built and tested at the Shanghai Synchrotron Radiation Facility (SSRF) based on the addition of permanent magnets. This prototype can realize magnetic compensation under various polarization modes in all working gaps, thereby reducing the deformation of the girders and maintaining sufficient rigidity of the mechanical structure. A girder deformation monitoring system was established to obtain real force compensation feedback. The final magnetic field measurement results meet the physical requirements, and the proposed scheme can be used as an alternative to the EPU with a high magnetic field and large magnetic force.