A seven-crystal spectrometer for high-energy resolution X-ray spectroscopy at Shanghai Synchrotron Radiation Facility

A Johann-type X-ray spectrometer was successfully developed at the hard X-ray branch(in-vacuum undulator with a 24-mm periodic length)of the energy material beamline(E-line)at the Shanghai Synchrotron Radiation Facility(SSRF).This spectrometer was utilized to implement X-ray emission spectroscopy(XES),high-energy resolution fluorescence-detected X-ray absorption spectroscopy(HERFD-XAS),and resonant inelastic X-ray scattering.Seven spherically bent crystals were positioned on the respective vertical 500-mm-diameter Rowland circles,adopting an area detector to increase the solid angle to 1.75%of 4πsr,facilitating the study of low-concentrate systems under complex reaction conditions.Operated under the atmosphere pressure,the spectrometer covers the energy region from 3.5 to 18 keV,with the Bragg angle ranging from 73°to 86°during vertical scanning.It offers a promised energy resolution of sub-eV(XES)and super-eV(HERFD-XAS).Generally,these comprehensive core-level spectroscopy methods based on hard X-rays at the E-line with an extremely high photon flux can meet the crucial requirements of a green energy strategy.Moreover,they provide substantial support for scientific advances in fundamental research.

Optimized online filter stack spectrometer for ultrashort X-ray pulses

Currently,with the advent of high-repetition-rate laser-plasma experiments,the demand for online diagnosis for the X-ray spectrum is increasing because the laser-plasma-generated X-ray spectrum is very important for characterizing electron dynamics and applications.In this study,scintillators and silicon PIN(P-type–intrinsic-N-type semiconductor)diodes were used to construct a wideband online filter stack spectrometer.The X-ray sensor and filter arrangement was optimized using a genetic algorithm to minimize the condition number of the response matrix.Consequently,the unfolding error was significantly reduced based on numerical experiments.The detector responses were quantitatively calibrated by irradiating the scintillator and PIN diode with various nuclides and comparing the measuredγ-ray peaks.A prototype 15-channel spectrometer was developed by integrating an X-ray detector with front-and back-end electronics.The prototype spectrometer could record X-ray pulse signals at a repetition rate of 1 kHz.Furthermore,an optimized spectrometer was employed to record the real-time spectra of laser-driven bremsstrahlung sources.This optimized spectrometer offers a compact solution for spectrum diagnostics of ultrashort X-ray pulses,exhibiting improved accuracy in terms of spectrum measurements and repetition rates,and could be widely used in next-generation high-repetition-rate high-power laser facilities.

Spectrometer of hard X-ray imager payload onboard the ASO-S mission

A spaceborne hard X-ray spectrometer, composed of an array of 99 scintillation detectors and associated readout electronics, has been developed for the hard X-ray imager(HXI). The HXI is one of the three payloads onboard the advanced space-based solar observatory(ASO-S), which is scheduled to be launched in early 2022 as the first Chinese solar satellite. LaBr3 scintillators and photomultiplier tubes with a super bialkali cathode are used to achieve an energy resolution better than 20% at 30 keV.Further, a new multi-channel charge-sensitive readout application-specific integrated circuit guarantees high-frequency data acquisition with low power consumption. This paper presents a detailed design of the spectrometer for the engineering model of the HXI and discusses its noise and linearity performance.

Test of a High Throughput Detector on the X-ray Crystal Spectrometer of the EAST

An attempt was made to improve the spatio-temporal resolution of the tangen- tial X-ray crystal spectrometer （XCS） on the Experimental Advanced Superconducting Tokamak （EAST） by evaluating experimentally the applicability of a novel X-ray photon detection tech- nology for measuring the satellite spectra of Ar XVII with a high counting rate. High-resolution experimental data on the profiles of ion temperature and plasma rotation velocity facilitate the studies of the mechanisms underlining important physical phenomena, such as plasma heating, L-H transition and momentum transport. Based on silicon diode array and single-photon counting technology, a relatively small area （83.8 x 33.5 mm~） two-dimensional detector was successfully in- stalled and tested in the recent EAST campaign. X-ray photon counting rate higher than 20 MHz was observed for the first time, and high quality satellite spectra were recorded for ion temperature and plasma rotation measurement, indicating that the new technology is suitable for the next-step high-resolution XCS on EAST, and the deployment of a detector array with a much larger X-ray sensing area is planned for better plasma coverage.

Design of Time-Resolved Shifted Dual Transmission Grating Spectrometer for the X-Ray Spectrum Diagnostics

A new time-resolved shifted dual transmission grating spectrometer （SDTGS） is designed and fabricated in this work. This SDTGS uses a new shifted dual transmission grating （SDTG） as its dispersive component, which has two sub transmission gratings with different line densities, of 2000 lines/mm and 5000 lines/mm. The axes of the two sub transmission gratings in SDTG are horizontally and vertically shifted a certain distance to measure a broad range of 0.1-5 keV time-resolved X-ray spectra. The SDTG has been calibrated with a soft X-ray beam of the synchrotron radiation facility and its diffraction efficiency is also measured. The designed SDTGS can take full use of the space on a record panel and improve the precision for measuring spatial and temporal spectrum simultaneously. It will be a promising application for accurate diagnosis of the soft X-ray spectrum in inertial confinement fusion.

High performance streaked X-ray spectrometer for research of laser-produced plasmas

In order to mitigate the effect of the strong electromagnetic pulse, which produces laser-plasma interactions, we designed a new streaked X-ray spectrometer （SXS） enclosed within a well-sealed, electromag- netic interference-free cavity. The SXS can cover a wide selection of spectral windows using interchangeable Bragg crystals and by appropriate adjustment of the Bragg angle. The SXS has been used to observe time-re- solved X-ray spectrum in the 2.5 keV to 3.5 keV photon-energy range, resulting in a demonstrated spectral res- olution of about 13 at 2960 eV with a time resolution of 10 ps. The observed time and spectral resolutions dem- onstrate the applicability of the SXS for studies of laser-produced plasmas.

Measurement of tungsten impurity spectra with a two-crystal X-ray crystal spectrometer on EAST

Spectral measurement of tungsten(W)impurity is essential to study impurity transport.Therefore,an X-ray crystal spectrometer(XCS)on EAST was used to measure the line spectra from highly ionized W ions.On EAST,both poloidal XCS and tangential XCS have been developed to measure the plasma temperature as well as the rotation velocity.Recently,He-like and H-like argon spectra have also been obtained using a two-crystal setup.W lines are identified in this study.Through a careful analysis,the W lines of 3.9336,3.9321,and 3.664(A)are found to be diffracted by He-like or H-like crystals.The lines are confirmed with the NIST database.We also calculated the ion temperature with Doppler broadening of these lines.The ion temperature from the W lines is entirely consistent with that from Ar line spectra.The measurement of these W line spectra could be used to study W impurity transport in future work.

Measurement of impurity lines with two-crystal x-ray spectrometers on EAST

To simultaneously measure the He-like and H-like argon spectra, a two-crystal assembly has been deployed to replace the previous single crystal on the tangential x-ray crystal spectrometer.By selecting appropriate crystals with similar Bragg angles, plasma temperature in the range of 0.5 keV≤Te≤10 keV and rotation can be diagnosed based on the He-like and H-like argon spectra. However, due to the added complexity in the two-crystal assembly in which the spectra might be diffracted by two crystals, some additional impurity lines were identified. For example,tungsten（W） lines in different ionization states were diffracted by the He-like and H-like crystal.Additional molybdenum（Mo） lines in the wavelength range of He-like and H-like argon spectra lines were also summarized. The existence of these additional lines caused the fitted temperature to be different from the true values. This paper presents the identified lines through a comparison with available database, which should be included in the fitting procedure.

A High-Efficiency X-Ray Crystal Spectrometer for X-Ray Thomson Scattering

Highly oriented pyrolitic graphite （HOPG） has high X-ray diffraction efficiency due to its unique mosaic crystal structure, and thus is very suitable for its application to X-ray Thomson scattering measurement of solid-density plasmas. In this article, by using the K-shell X-ray source from laser-produced Ti plasma, the properties of the HOPG spectrometer are characterized and compared with those of the flat Pentaerythritol （PET） spectrometer. The results show that the diffraction efficiency of the HOPG spectrometer under focusing condition is an order higher than that of the PET spectrometer, while the spectral resolution of the HOPG is about 320, high enough to be used in the measurement of X-ray Thomson scattering spectra.

Ray tracing method for the grazing incidence flat-field imaging soft X-ray spectrometer

A ray tracing method is introduced for helping adjustment and spectra analysis of the grazing incidence flat-field imaging soft X-ray spectrometer. For a single point source, the spectra images obtained by separate components, the toroidal mirror, and the grazing incidence flat-field concave grating with varied line spaces are given respectively. The calculated spectral images of the single point source by the spectrometer are also given for comparison with measurements with different experimental alignments.

Design and calibration of an elliptical crystal spectrometer for the diagnosis of proton-induced x-ray emission(PIXE)

Laser-driven proton-induced x-ray emission(laser-PIXE) is a nuclear analysis method based on the compact laser ion accelerator. Due to the transient process of ion acceleration, the laser-PIXE signals are usually spurted within nanoseconds and accompanied by strong electromagnetic pulses(EMP), so traditional multi-channel detectors are no longer applicable.In this work, we designed a reflective elliptical crystal spectrometer for the diagnosis of laser-PIXE. The device can detect the energy range of 1 keV–11 ke V with a high resolution. A calibration experiment was completed on the electrostatic accelerator of Peking University using samples of Al, Ti, Cu, and ceramic artifacts. The detection efficiency of the elliptical crystal spectrometer was obtained in the order of 10-9.

Accuracy analysis of iron content of galvanized coating using an X-ray fluorescence spectrometer with an L-spectrum

The accuracy(repeatability and reproducibility) of the iron content analysis of galvanized coating using an X-ray fluorescence spectrometer with an L-spectrum is not better than that of flame atomic absorption spectrometry, sometimes it exceeds the quality control limit.Influences, such as current, voltage, equipment(internal circulating water, 10%CH4+90%Ar, and vacuum) checking, instrument monitoring, sample cleaning, and oper-ators, were investigated by means of 6-sigma and lean operations to improve accuracy.

A New Method for Measurements of the Poloidal Rotation Velocities and Wavelength Calibration of X-ray Imaging Crystal Spectrometer in Magnetic Fusion Devices

A new simple method is presented for the wavelength calibration and measurement of poloidal rotation velocities with X-ray imaging crystal spectrometer（XICS）in magnetic fusion devices.In this method,the toroidal rotation of plasma is applied for high precise alignment and wavelength calibration of the poloidal XICS.The measurement threshold of poloidal rotation velocity can be lowered to 1-3 km/s with this method.

A study on some elements and their phases in sediments of Changjiang Estuary by X-ray spectrometer and X-ray diffractometer

INTRODUCTIONThe studies on the quantitative distribution of the conventional elements and their phases in the sediments of the Changjiang Estuary are of great importance to the understanding of the chemical processes of ion exchange, absorption, desorption and flocculation in the estuary.

A Reflectron Time-of-Flight Mass Spectrometer with a Nano-Electrospray Ionization Source for Study of Metal Cluster Compounds

An experiment facility has been set up for the study of metal cluster compounds in our laboratory, which consists of a nano-electrospray ionization source, an ion transmission and focus system, and a reflectron time-of-fight mass spectrometer. Taking advantage of the nano-electrospray ionization source, polyvalent ions are usually produced in the ＂ionization＂ process and the obtained mass resolution of the equipment is over 8000. The molecular ion peaks of metal cluster compounds [Au20（PPhpy2）10Cl2]（SbF6）4, where PPhpy2=bis（2- pyridyl）phenylphosphine, and [AuaAg2（C）L6]（BF4）4, where L=2-（diphenylphosphino）-5- methylpyridine, are distinguished in the respective mass spectrum, accompanied by some fragment ion peaks. In addition, the mass-to-charge ratios of the parent ions are determi- nated. Preliminary results suggest that the device is a powerful tool for the study of metal cluster compounds. It turns out that the information obtained by the instrumentation serves as an essential supplement to single crystal X-ray diffraction for structure characterization of metal cluster compounds.

Understanding fundamentals of electrochemical reactions with tender X-rays:A new lab-based operando X-ray photoelectron spectroscopy method for probing liquid/solid and gas/solid interfaces across a variety of electrochemical systems

Electrocatalysis is key to improving energy efficiency,reducing carbon emissions,and providing a sustainable way of meeting global energy needs.Therefore,elucidating electrochemical reaction mechanisms at the electrolyte/electrode interfaces is essential for developing advanced renewable energy technologies.However,the direct probing of real-time interfacial changes,i.e.,the surface intermediates,chemical environment,and electronic structure,under operating conditions is challenging and necessitates the use of in situ methods.Herein,we present a new lab-based instrument commissioned to perform in situ chemical analysis at liquid/solid interfaces using ambient pressure X-ray photoelectron spectroscopy(APXPS).This setup takes advantage of a chromium source of tender X-rays and is designed to study liquid/solid interfaces by the“dip and pull”method.Each of the main components was carefully described,and the results of performance tests are presented.Using a three-electrode setup,the system can probe the intermediate species and potential shifts across the liquid electrolyte/solid electrode interface.In addition,we demonstrate how this system allows the study of interfacial changes at gas/solid interfaces using a case study:a sodium–oxygen model battery.However,the use of APXPS in electrochemical studies is still in the early stages,so we summarize the current challenges and some developmental frontiers.Despite the challenges,we expect that joint efforts to improve instruments and the electrochemical setup will enable us to obtain a better understanding of the composition–reactivity relationship at electrochemical interfaces under realistic reaction conditions.

X-ray absorption near the edge structure and x-ray photoelectron spectroscopy studies on pyrite prepared by thermally sulfurizing iron films

This paper reports how pyrite films were prepared by thermal sulfurization of magnetron sputtered iron films and characterized by X-ray absorption near edge structure spectra and X-ray photoelectron spectroscopy on a 4B9B beam line at the Beijing Synchrotron Radiation Facility. The band gap of the pyrite agrees well with the optical band gap obtained by a spectrophotometer. The octahedral symmetry of pyrite leads to the splitting of the d orbit into t2g and eg levels. The high spin and low spin states were analysed through the difference of electron exchange interaction and the orbital crystal field. Only when the crystal field splitting is higher than 1.5 eV, the two weak peaks above the white lines can appear, and this was approved by experiments in the present work.

Photoelectric characteristics of silicon P–N junction with nanopillar texture:Analysis of X-ray photoelectron spectroscopy

Silicon nanopillars are fabricated by inductively coupled plasma （ICP） dry etching with the cesium chloride （CsCl） islands as masks originally from self-assembly. Wafers with nanopillar texture or planar surface are subjected to phosphorus （P） diffusion by liquid dopant source （POCl3） at 870 ℃ to form P-N junctions with a depth of 300 nm. The X-ray photoelectron spectroscopy （XPS） is used to measure the Si 2p core levels of P-N junction wafer with nanopillar texture and planar surface. With a visible light excitation, the P-N junction produces a new electric potential for photoelectric characteristic, which causes the Si 2p core level to have a energy shift compared with the spectrum without the visible light. The energy shift of the Si 2p core level is -0.27 eV for the planar P-N junction and -0.18 eV for the nanopillar one. The difference in Si 2p energy shift is due to more space lattice defects and chemical bond breaks for nanopillar compared with the planar one.

X-ray Photoelectron Spectroscopy Studies of Ti_(x)Al_(1-x)N Thin Films Prepared by RF Reactive Magnetron Sputtering

TixAl1-xN films have been prepared by RF reactive magnetron sputtering. X-ray diffraction results showed that TixAl1-xN thin films in this study were hexagonal wurtzite structure with the Ti content up to 0.18. X-ray photoelectron spectrocopy studies provided that the Nls core-electron spectrum of TixAl1-xN thin film brodend with increasing Ti content, and the difference of the chemical shifts for Ti2p3/2 line between TiN and TixAl1-xN th77pj in film was 0.7 eV.

Application of a Portable XRF Spectrometer for <i>In-Situ</i>and Nondestructive Investigation of Pigments in Two 15th Century Icons

A simple portable X-Ray Fluorescence (XRF) spectrometer was successfully used for in-situ and nondestructive identification of the painting materials in two 15th century icons from the Onufri Museum in Beart, Albania. The spectrometer is based on a low power X-ray tube, a thermoelectrically cooled Si PIN detector and the spectrum acquisition system. It was assembled and adjusted at our laboratory for the investigation of the icons. A small number of pigments were clearly identified by X-Ray Fluorescence (XRF) measurements in both icons. This includes Lead white for the white color, gold and yellow ochre for the yellow color, red lead, cinnabar and red ochre for the red color, as well as cooper based pigments for the green color. At the same time, the investigation raised some new questions that need further investigations by the use of additional analytical techniques. The results show that in both icons are used similar pigments, which are in accordance with the Byzantine icon painting tradition.