Solar wind charge exchange(SWCX)is the process of solar wind high-valence ions exchanging charges with neutral components and generating soft X-rays.Recently,detecting the SWCX emission from the magnetosphere is propo...Solar wind charge exchange(SWCX)is the process of solar wind high-valence ions exchanging charges with neutral components and generating soft X-rays.Recently,detecting the SWCX emission from the magnetosphere is proposed as a new technique to study the magnetosphere using panoramic soft X-ray imaging.To better prepare for the data analysis of upcoming magnetospheric soft X-ray imaging missions,this paper compares the magnetospheric SWCX emission obtained by two methods in an XMM-Newton observation,during which the solar wind changed dramatically.The two methods differ in the data used to fit the diffuse X-ray background(DXB)parameters in spectral analysis.The method adding data from the ROSAT All-Sky Survey(RASS)is called the RASS method.The method using the quiet observation data is called the Quiet method,where quiet observations usually refer to observations made by the same satellite with the same target but under weaker solar wind conditions.Results show that the spectral compositions of magnetospheric SWCX emission obtained by the two methods are very similar,and the changes in intensity over time are highly consistent,although the intensity obtained by the RASS method is about 2.68±0.56 keV cm^(-2)s^(-1)sr^(-1)higher than that obtained by the Quiet method.Since the DXB intensity obtained by the RASS method is about 2.84±0.74 keV cm^(-2)s^(-1)sr^(-1)lower than that obtained by the Quiet method,and the linear correlation coefficient between the difference of SWCX and DXB obtained by the two methods in diffe rent energy band is close to-1,the diffe rences in magnetospheric SWCX can be fully attributed to the diffe rences in the fitted DXB.The difference between the two methods is most significant when the energy is less than 0.7 keV,which is also the main energy band of SWCX emission.In addition,the difference between the two methods is not related to the SWCX intensity and,to some extent,to solar wind conditions,because SWCX intensity typically va ries with the solar wind.In summary,both methods are robust and reliable,and should be considered based on the best available options.展开更多
The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magne...The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magnetic field turning and produce SXI count maps with a 5-minute integration time.By making assumptions about the magnetopause shape,we find the magnetopause standoff distance from the count maps and compare it with the one obtained directly from the magnetohydrodynamic(MHD)simulation.The root mean square deviations between the reconstructed and MHD standoff distances do not exceed 0.2 RE(Earth radius)and the maximal difference equals 0.24 RE during the 25-minute interval around the southward turning.展开更多
Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosph...Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)aims to capture two-dimensional(2-D)images of the Earth’s magnetosheath by using soft X-ray imaging.However,the observed 2-D images are affected by many noise factors,destroying the contained information,which is not conducive to the subsequent reconstruction of the three-dimensional(3-D)structure of the magnetopause.The analysis of SXI-simulated observation images shows that such damage cannot be evaluated with traditional restoration models.This makes it difficult to establish the mapping relationship between SXIsimulated observation images and target images by using mathematical models.We propose an image restoration algorithm for SXIsimulated observation images that can recover large-scale structure information on the magnetosphere.The idea is to train a patch estimator by selecting noise–clean patch pairs with the same distribution through the Classification–Expectation Maximization algorithm to achieve the restoration estimation of the SXI-simulated observation image,whose mapping relationship with the target image is established by the patch estimator.The Classification–Expectation Maximization algorithm is used to select multiple patch clusters with the same distribution and then train different patch estimators so as to improve the accuracy of the estimator.Experimental results showed that our image restoration algorithm is superior to other classical image restoration algorithms in the SXI-simulated observation image restoration task,according to the peak signal-to-noise ratio and structural similarity.The restoration results of SXI-simulated observation images are used in the tangent fitting approach and the computed tomography approach toward magnetospheric reconstruction techniques,significantly improving the reconstruction results.Hence,the proposed technology may be feasible for processing SXI-simulated observation images.展开更多
Based on the synchrotron soft X-ray absorption spectroscopy experiments,the fundamental electronic structures of layered Li NixCoyMnzO_(2)(NCM)are investigated systematically and the data of transitionmetal(TM)L-and O...Based on the synchrotron soft X-ray absorption spectroscopy experiments,the fundamental electronic structures of layered Li NixCoyMnzO_(2)(NCM)are investigated systematically and the data of transitionmetal(TM)L-and O K-edges spectra are collected.Distribution of Ni ions under different oxidation states is evaluated according to linear combination fit.It is found that the ratio of Ni^(4+)expands with the increase of Ni since it dominates in charge compensation during charging,and that the existence of Ni^(3+)is nearly negligible in delithiated NCM.The valence state of Co also strongly depends on Ni content,the perceptible position shift of Co L_(3)-edge absorption peak towards higher energy in Ni-rich material agrees well with the small voltage plateau at around 4.2 V.The stability of Mn is verified as no obvious spectral change with the Mn L-edge is observed.Moreover,as Ni content rises,the O 2p holes near the Femi level increases with higher oxidation state of Ni,indicating the enhanced hybridization of O 2p-TM 3 d.Delithiated NCMs with higher Ni content are prior to lose electron existing in highly hybridized Ni3 dO 2 p bands upon heating,which accounts for the pronounced O_(2)release in phase transitions and the deterioration in thermal stability.These detailed observation of the electronic structure evolution is one of the key ingredients to improving the electrochemical and thermal performance of NCM.展开更多
Understanding electronic structure is crucial to enhance the battery performance. Soft X-ray spectroscopy(SXS) is one of the most effective methods to provide direct probe of electronic states. Here, spectroscopic mea...Understanding electronic structure is crucial to enhance the battery performance. Soft X-ray spectroscopy(SXS) is one of the most effective methods to provide direct probe of electronic states. Here, spectroscopic measurements of transition metal 3 d and oxygen 2 p states are simply reviewed. Then, we mainly focus on the perspective of the development direction of modern SXS techniques. Although the true power of recently developed high efficiency mapping of resonant inelastic X-ray scattering(m RIXS) has been apparent for materials and chemistry studies, great challenges remain for mRIXS spectroscopic interpretation, and the understanding of the battery materials on novel redox activities remains elusive.展开更多
The lightweight,rechargeable lithium-ion battery is one of the dominant energy storage devices globally in portable electronics due to its high energy density,no memory effect,wide operating voltage,lightweight,and go...The lightweight,rechargeable lithium-ion battery is one of the dominant energy storage devices globally in portable electronics due to its high energy density,no memory effect,wide operating voltage,lightweight,and good charge efficiency.However,due to safety concerns,the depletion of lithium reserves,and the corresponding increase of cost,an alternative battery system becomes more and more desirable.To develop alternative battery systems with low cost and high material abundance,for example,sodium,magnesium,zinc,and calcium,it is important to understand the chemical and electronic structure of materials.Soft X-ray spectroscopy,for example,X-ray absorption spectroscopy(XAS),X-ray emission spectroscopy(XES),and resonant inelastic soft X-ray scattering(RIXS),is an element-specific technique with sensitivity to the local chemical environment and structural order of the element of interest.Modern soft X-ray systems enable operando experiments that can be applied to amorphous and crystalline samples,making it a powerful tool for studying the electronic and structural changes in electrode and electrolyte species.In this article,the application of in situ/operando(soft)X-ray spectroscopy in beyond lithium-ion batteries is reviewed to demonstrate how such spectroscopic characterizations could facilitate the interpretation of interfacial phenomena under in situ/operando condition and subsequent development of the beyond lithium-ion batteries.展开更多
The formidable challenge of developing high-performance battery system stems from the complication of battery operations, both mechanically and electronically. In the electrodes and at the electrode-electrolyte interf...The formidable challenge of developing high-performance battery system stems from the complication of battery operations, both mechanically and electronically. In the electrodes and at the electrode-electrolyte interfaces, chemical reactions take place with evolving electron states. In addition to the extensive studies of material synthesis, electrochem- ical, structural, and mechanical properties, soft x-ray spectroscopy provides unique opportunities for revealing the critical electron states in batteries. This review discusses some of the recent soft x-ray spectroscopic results on battery binder, transition-metal based positive electrodes, and the solid-electrolyte-interphase. By virtue of soft x-ray's sensitivity to electron states, the electronic property, the redox during electrochemical operations, and the chemical species of the interphases could be fingerprinted by soft x-ray spectroscopy. Understanding and innovating battery technologies need a multimodal approach, and soft x-ray spectroscopy is one of the incisive tools to probe the chemical and physical evolutions in batteries.展开更多
By using soft X-ray spectroscopy, we investigate the inner-shell excitation and relaxation processes in atomic and ionic neon targets. Resonant X-ray emission spectroscopy was applied to neutral neon atom in the regio...By using soft X-ray spectroscopy, we investigate the inner-shell excitation and relaxation processes in atomic and ionic neon targets. Resonant X-ray emission spectroscopy was applied to neutral neon atom in the regions of the [1s]np (n = 3, 4,…, ε) excited states and [1s2p]3pmp (m = 3,4) doubly excited states to obtain the spectroscopic information on the [2p]np and [2p^2]3prnp final electronic states, where square brackets indicate hole states. The energy levels of the [2p^2]3prnp (m = 3,4) electronic states were spectroscopically measured for the first time. As for the ionic neon target, on the other hand, the photoion yield spectroscopy was adopted to survey the 1s→ np (n = 2, 3) resonant excitation and subsequent Auger decay processes for Ne^+ target-ions. The observed Ne^2+ photoion yield spectrum is successflllly explained by the theoretical calculations based on the nmlticonfiguration Dirac-Fock method展开更多
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 ...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.展开更多
The visualization and data mining of tumor multidimensional information may play a major role in the analysis of the growth,metastasis,and microenvironmental changes of tumors while challenging traditional imaging and...The visualization and data mining of tumor multidimensional information may play a major role in the analysis of the growth,metastasis,and microenvironmental changes of tumors while challenging traditional imaging and data processing techniques.In this study,a general trans-scale and multi-modality measurement method was developed for the quantitative diagnosis of hepatocellular carcinoma(HCC)using a combination of propagation-based phase-contrast computed tomography(PPCT),scanning transmission soft X-ray microscopy(STXM),and Fourier transform infrared micro-spectroscopy(FTIR).Our experimental results reveal the trans-scale micro-morpho-logical HCC pathology and facilitate quantitative data analysis and comprehensive assessment.These results include some visualization features of PPCT-based tissue microenvironments,STXM-based cellular fine structures,and FTIR-based bio-macromolecular spectral characteris-tics during HCC tumor differentiation and proliferation.The proposed method provides multidimensional feature data support for constructing a high-accuracy machine learning algorithm based on a gray-level histogram,gray-gradient co-occurrence matrix,gray-level co-occurrence matrix,and back-propagation neural network model.Multi-dimensional information analysis and diagnosis revealed the morphological pathways of HCC pathological evolution and we explored the relationships between HCC-related feature changes in inflammatory microenviron-ments,cellular metabolism,and the stretching vibration peaks of biomolecules of lipids,proteins,and nucleic acids.Therefore,the proposed methodology has strong potential for the visualization of complex tumors and assessing the risks of tumor differentiation and metastasis.展开更多
Breakthroughs in energy storage and conversion devices depend heavily on the exploration of low-cost and high-performance materials.Carbon-supported electrocatalysts with dimensional varieties have recently attracted ...Breakthroughs in energy storage and conversion devices depend heavily on the exploration of low-cost and high-performance materials.Carbon-supported electrocatalysts with dimensional varieties have recently attracted significant attention due to their strong structural flexibility and easy accessibility.Nevertheless,understanding the connection between their electronic,structural properties,and catalytic performance must remain a top priority.Synchrotron radiation(SR)X-ray absorption spectroscopy(XAS)techniques,including hard XAS and soft XAS,are recognized as efficient and comprehensive platforms for probing the surface,interface,and bulk electronic structure of elements of interest in the materials community.In the past decade,the flourishing development of materials science and advanced characterization technologies have led to a deeper understanding at different temporal,longitudinal,and spatial scales.In this review,we briefly describe the concept of XAS techniques and summarize their recent progress in addressing scientific questions on carbon-supported electrocatalysts through the development of advanced instruments and experimental methods.We then discuss the remaining challenges and potential research directions in nextgeneration materials frontiers,and suggest challenges and perspectives for shedding light on the structure–activity relationship.展开更多
In this paper we have reviewed our achievements in soft X-ray and extreme ultraviolet (EUV) optics. Up to now, the research system of soft X-ray and EUV optics has been established, including light sources, detectors,...In this paper we have reviewed our achievements in soft X-ray and extreme ultraviolet (EUV) optics. Up to now, the research system of soft X-ray and EUV optics has been established, including light sources, detectors, calibrations, optical testing and machining of super smooth mirrors, and fabrications of multilayer film mirrors. Based on our achievements, we have developed two types of solar space telescopes for the soft X-ray and EUV space solar observations. One is an EUV multilayer normal incident telescope array including 4 different operation wavelength telescopes. The operation wavelengths of the EUV telescope are 13.0, 17.1, 19.5 and 30.4 nm. The other is a complex space solar telescope, which is composed of an EUV multilayer normal incident telescope and a soft X-ray grazing incident telescope. The EUV multilayer normal incident telescope stands in the central part of the soft X-ray grazing incident telescope. The normal incident telescope and the grazing incident telescope have a common detector. The different operation wavelengths can be changed by rotating a filter wheel.展开更多
Nickel based magnetic nanocrystals have been widely applied in magnetic and catalytic facilities.Tunable magnetic properties of nickel can be easily obtained via non-magnetic doping or phase transformation.However,pha...Nickel based magnetic nanocrystals have been widely applied in magnetic and catalytic facilities.Tunable magnetic properties of nickel can be easily obtained via non-magnetic doping or phase transformation.However,phase transformation from face centered cubic(fcc)to hexagonal close packed(hcp)induced magnetism adjustment of Ni are always confused with nickel carbide(Ni_(3)C),due to the similar atomic structures of hcp-Ni and Ni3C.Here,we present series of Au@Ni-carbide magnetic materials achieved from the controlled carbonation of Au@Ni core-shell structures,whose magnetism is tunable by adjusting the amount of carbon in the Ni layer.Ex-situ hard X-ray absorption spectroscopy(XAS)at the metal K edge and soft XAS at both metal L edge and carbon K edge provide solid evidence for the carbonation process from fcc-Ni to Ni_(x)C,rather than phase transformation to hcp-Ni.Further investigation reveals that the magnetism of the hybrids is mainly contributed from the residual fcc-Ni.The result represents an accurate and effective way to distinguish hexagonal Ni_(3)C from hcp-Ni,and provides the pathway to control magnetism of Ni-based materials for applications.展开更多
By virtue of the crucial effect of the crystal structure and transition metal(TM)redox evolution on the performance of LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM)cathode,systematical investigation is carried out to better understa...By virtue of the crucial effect of the crystal structure and transition metal(TM)redox evolution on the performance of LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM)cathode,systematical investigation is carried out to better understand the charge mechanism upon deep charging.Based on the results of X-ray diffraction and highresolution transmission electron microscope,phase transformations existing on particle surface are promoted by high potential because of the deeper lithium vacancies,accompanied by more substantial structure instability.Soft X-ray absorption spectroscopy indicates that Ni acts as the major contributor to charge compensation while Co displays a remarkable redox activity over the deep charge range.The elevated integrated intensity of pre-edge in O K-edge spectra reveals the extensive amount of holes formed in O 2 p orbitals and the enhanced hybridization of TM 3 d-O 2 p orbitals.Considering the close relationship between thermal behavior and structural evolution,the tendency of phase transitions and O_(2) release upon heating is accelerated by voltage rise,demonstrating the aggravated instability due to deeper Li utilization.Remaining Li contents in NCM are employed to estimate the amount of oxygen released in structural transformation and its detrimental effect on stability declares Li contentdependent characteristics.Furthermore,the extended Li vacancies,higher proportion of Ni4+and stronger orbital hybridization are considered as three factors impeding the thermal stability of the highlydelithiated NCM.展开更多
Despite acknowledgment of structural reconstruction of materials following oxygen evolution reaction (OER) reaction, the role of support during the reconstruction process has been ignored. Given this, we directly in s...Despite acknowledgment of structural reconstruction of materials following oxygen evolution reaction (OER) reaction, the role of support during the reconstruction process has been ignored. Given this, we directly in situ transform the residual iron present in raw single-walled carbon nanotubes (SWCNT) into Fe_(2)O_(3) and thus build Fe_(2)O_(3)-CNT as the model system. Intriguingly, an anomalous self-optimization occurred on SWCNT and the derived components show satisfactory electrochemical performance. Soft X-ray absorption spectroscopy (sXAS) analysis and theory calculation correspondingly indicate that self-optimization yields stronger interaction between SWCNT and Fe_(2)O_(3) nanoparticles, where the electrons migrate from Fe_(2)O_(3) to optimized SWCNT. Such polarization will generate a positive charge center and thus boost the OER activity. This finding directly observes the self-optimization of support effect, providing a new perspective for OER and related electrochemical reactions.展开更多
Over the past decades,imaging and spectroscopy techniques have been developed rapidly with widespread applications in non-destructive agro-food quality determination.Seeds are one of themost fundamental elements of ag...Over the past decades,imaging and spectroscopy techniques have been developed rapidly with widespread applications in non-destructive agro-food quality determination.Seeds are one of themost fundamental elements of agriculture and forestry.Seed viability is of great significance in seed quality characteristics reflecting potential seed germination,and there is a great need for a quick and effective method to determine the germination condition and viability of seeds prior to cultivate,sale and plant.Some researches based on spectra and/or image processing and analysis have been explored in terms of the external and internal quality of a variety of seeds.Many attempts have been made in image segmentation and spectra correction methods to predict seed quality using various traditional and novel methods.This review focuses on the comparative introduction,development and applications of emerging techniques in the analysis of seed viability,in particular,near infrared spectroscopy,hyperspectral and multispectral imaging,Raman spectroscopy,infrared thermography,and soft X-ray imaging methods.The basic theories,principle components,relative chemometric processing,analytical methods and prediction accuracies are reported and compared.Additionally,on the foundation of the observed applications,the technical challenges and future outlook for these emerging techniques are also discussed.展开更多
基金supported by NNSFC grants 42322408,42188101 and 42074202the Strategic Pioneer Program on Space Science,CAS Grant nos.XDA15350201+3 种基金in part by the Research Fund from the Chinese Academy of Sciencesthe Specialized Research Fund for State Key Laboratories of China.supported by the Young Elite Scientists Sponsorship Program(CAST-Y202045)supported by Royal Society grant DHFR1211068。
文摘Solar wind charge exchange(SWCX)is the process of solar wind high-valence ions exchanging charges with neutral components and generating soft X-rays.Recently,detecting the SWCX emission from the magnetosphere is proposed as a new technique to study the magnetosphere using panoramic soft X-ray imaging.To better prepare for the data analysis of upcoming magnetospheric soft X-ray imaging missions,this paper compares the magnetospheric SWCX emission obtained by two methods in an XMM-Newton observation,during which the solar wind changed dramatically.The two methods differ in the data used to fit the diffuse X-ray background(DXB)parameters in spectral analysis.The method adding data from the ROSAT All-Sky Survey(RASS)is called the RASS method.The method using the quiet observation data is called the Quiet method,where quiet observations usually refer to observations made by the same satellite with the same target but under weaker solar wind conditions.Results show that the spectral compositions of magnetospheric SWCX emission obtained by the two methods are very similar,and the changes in intensity over time are highly consistent,although the intensity obtained by the RASS method is about 2.68±0.56 keV cm^(-2)s^(-1)sr^(-1)higher than that obtained by the Quiet method.Since the DXB intensity obtained by the RASS method is about 2.84±0.74 keV cm^(-2)s^(-1)sr^(-1)lower than that obtained by the Quiet method,and the linear correlation coefficient between the difference of SWCX and DXB obtained by the two methods in diffe rent energy band is close to-1,the diffe rences in magnetospheric SWCX can be fully attributed to the diffe rences in the fitted DXB.The difference between the two methods is most significant when the energy is less than 0.7 keV,which is also the main energy band of SWCX emission.In addition,the difference between the two methods is not related to the SWCX intensity and,to some extent,to solar wind conditions,because SWCX intensity typically va ries with the solar wind.In summary,both methods are robust and reliable,and should be considered based on the best available options.
基金support from the UK Space Agency under Grant Number ST/T002964/1partly supported by the International Space Science Institute(ISSI)in Bern,through ISSI International Team Project Number 523(“Imaging the Invisible:Unveiling the Global Structure of Earth’s Dynamic Magnetosphere”)。
文摘The Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)Soft X-ray Imager(SXI)will shine a spotlight on magnetopause dynamics during magnetic reconnection.We simulate an event with a southward interplanetary magnetic field turning and produce SXI count maps with a 5-minute integration time.By making assumptions about the magnetopause shape,we find the magnetopause standoff distance from the count maps and compare it with the one obtained directly from the magnetohydrodynamic(MHD)simulation.The root mean square deviations between the reconstructed and MHD standoff distances do not exceed 0.2 RE(Earth radius)and the maximal difference equals 0.24 RE during the 25-minute interval around the southward turning.
基金supported by the National Natural Science Foundation of China(Grant Nos.42322408,42188101,41974211,and 42074202)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.QYZDJ-SSW-JSC028)+1 种基金the Strategic Priority Program on Space Science,Chinese Academy of Sciences(Grant Nos.XDA15052500,XDA15350201,and XDA15014800)supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.Y202045)。
文摘Astronomical imaging technologies are basic tools for the exploration of the universe,providing basic data for the research of astronomy and space physics.The Soft X-ray Imager(SXI)carried by the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)aims to capture two-dimensional(2-D)images of the Earth’s magnetosheath by using soft X-ray imaging.However,the observed 2-D images are affected by many noise factors,destroying the contained information,which is not conducive to the subsequent reconstruction of the three-dimensional(3-D)structure of the magnetopause.The analysis of SXI-simulated observation images shows that such damage cannot be evaluated with traditional restoration models.This makes it difficult to establish the mapping relationship between SXIsimulated observation images and target images by using mathematical models.We propose an image restoration algorithm for SXIsimulated observation images that can recover large-scale structure information on the magnetosphere.The idea is to train a patch estimator by selecting noise–clean patch pairs with the same distribution through the Classification–Expectation Maximization algorithm to achieve the restoration estimation of the SXI-simulated observation image,whose mapping relationship with the target image is established by the patch estimator.The Classification–Expectation Maximization algorithm is used to select multiple patch clusters with the same distribution and then train different patch estimators so as to improve the accuracy of the estimator.Experimental results showed that our image restoration algorithm is superior to other classical image restoration algorithms in the SXI-simulated observation image restoration task,according to the peak signal-to-noise ratio and structural similarity.The restoration results of SXI-simulated observation images are used in the tangent fitting approach and the computed tomography approach toward magnetospheric reconstruction techniques,significantly improving the reconstruction results.Hence,the proposed technology may be feasible for processing SXI-simulated observation images.
基金supported by the National Natural Science Foundation of China(No.51976209)the Fundamental Research Funds for the Central Universities(No.WK2320000040)supported by the Youth Innovation Promotion Association CAS(No.Y201768)。
文摘Based on the synchrotron soft X-ray absorption spectroscopy experiments,the fundamental electronic structures of layered Li NixCoyMnzO_(2)(NCM)are investigated systematically and the data of transitionmetal(TM)L-and O K-edges spectra are collected.Distribution of Ni ions under different oxidation states is evaluated according to linear combination fit.It is found that the ratio of Ni^(4+)expands with the increase of Ni since it dominates in charge compensation during charging,and that the existence of Ni^(3+)is nearly negligible in delithiated NCM.The valence state of Co also strongly depends on Ni content,the perceptible position shift of Co L_(3)-edge absorption peak towards higher energy in Ni-rich material agrees well with the small voltage plateau at around 4.2 V.The stability of Mn is verified as no obvious spectral change with the Mn L-edge is observed.Moreover,as Ni content rises,the O 2p holes near the Femi level increases with higher oxidation state of Ni,indicating the enhanced hybridization of O 2p-TM 3 d.Delithiated NCMs with higher Ni content are prior to lose electron existing in highly hybridized Ni3 dO 2 p bands upon heating,which accounts for the pronounced O_(2)release in phase transitions and the deterioration in thermal stability.These detailed observation of the electronic structure evolution is one of the key ingredients to improving the electrochemical and thermal performance of NCM.
文摘Understanding electronic structure is crucial to enhance the battery performance. Soft X-ray spectroscopy(SXS) is one of the most effective methods to provide direct probe of electronic states. Here, spectroscopic measurements of transition metal 3 d and oxygen 2 p states are simply reviewed. Then, we mainly focus on the perspective of the development direction of modern SXS techniques. Although the true power of recently developed high efficiency mapping of resonant inelastic X-ray scattering(m RIXS) has been apparent for materials and chemistry studies, great challenges remain for mRIXS spectroscopic interpretation, and the understanding of the battery materials on novel redox activities remains elusive.
基金supported as part of the Joint Center for Energy Storage Research(JCESR)an Energy Innovation Hub funded by the U.S.Department of Energy(DOE),Office of Science,Basic Energy Sciences
文摘The lightweight,rechargeable lithium-ion battery is one of the dominant energy storage devices globally in portable electronics due to its high energy density,no memory effect,wide operating voltage,lightweight,and good charge efficiency.However,due to safety concerns,the depletion of lithium reserves,and the corresponding increase of cost,an alternative battery system becomes more and more desirable.To develop alternative battery systems with low cost and high material abundance,for example,sodium,magnesium,zinc,and calcium,it is important to understand the chemical and electronic structure of materials.Soft X-ray spectroscopy,for example,X-ray absorption spectroscopy(XAS),X-ray emission spectroscopy(XES),and resonant inelastic soft X-ray scattering(RIXS),is an element-specific technique with sensitivity to the local chemical environment and structural order of the element of interest.Modern soft X-ray systems enable operando experiments that can be applied to amorphous and crystalline samples,making it a powerful tool for studying the electronic and structural changes in electrode and electrolyte species.In this article,the application of in situ/operando(soft)X-ray spectroscopy in beyond lithium-ion batteries is reviewed to demonstrate how such spectroscopic characterizations could facilitate the interpretation of interfacial phenomena under in situ/operando condition and subsequent development of the beyond lithium-ion batteries.
基金supported by the Director,Office of Science,Office of Basic Energy Sciences,of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231supported by the LDRD program at the Lawrence Berkeley National Laboratory
文摘The formidable challenge of developing high-performance battery system stems from the complication of battery operations, both mechanically and electronically. In the electrodes and at the electrode-electrolyte interfaces, chemical reactions take place with evolving electron states. In addition to the extensive studies of material synthesis, electrochem- ical, structural, and mechanical properties, soft x-ray spectroscopy provides unique opportunities for revealing the critical electron states in batteries. This review discusses some of the recent soft x-ray spectroscopic results on battery binder, transition-metal based positive electrodes, and the solid-electrolyte-interphase. By virtue of soft x-ray's sensitivity to electron states, the electronic property, the redox during electrochemical operations, and the chemical species of the interphases could be fingerprinted by soft x-ray spectroscopy. Understanding and innovating battery technologies need a multimodal approach, and soft x-ray spectroscopy is one of the incisive tools to probe the chemical and physical evolutions in batteries.
文摘By using soft X-ray spectroscopy, we investigate the inner-shell excitation and relaxation processes in atomic and ionic neon targets. Resonant X-ray emission spectroscopy was applied to neutral neon atom in the regions of the [1s]np (n = 3, 4,…, ε) excited states and [1s2p]3pmp (m = 3,4) doubly excited states to obtain the spectroscopic information on the [2p]np and [2p^2]3prnp final electronic states, where square brackets indicate hole states. The energy levels of the [2p^2]3prnp (m = 3,4) electronic states were spectroscopically measured for the first time. As for the ionic neon target, on the other hand, the photoion yield spectroscopy was adopted to survey the 1s→ np (n = 2, 3) resonant excitation and subsequent Auger decay processes for Ne^+ target-ions. The observed Ne^2+ photoion yield spectrum is successflllly explained by the theoretical calculations based on the nmlticonfiguration Dirac-Fock method
基金Project supported by the National Natural Science Foundation of China (Grant No 102750770)
文摘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.
基金supported by the Natural Science Foundation of Shandong Province,China(No.ZR2020MA088)Natural Science Foundation of Xinjiang Uygur Autonomous Region,China(No.2019D01C188)+1 种基金National Key Research and Development Program of China(No.2018YFC1200204)National Natural Science Foundation of China(No.12175127).
文摘The visualization and data mining of tumor multidimensional information may play a major role in the analysis of the growth,metastasis,and microenvironmental changes of tumors while challenging traditional imaging and data processing techniques.In this study,a general trans-scale and multi-modality measurement method was developed for the quantitative diagnosis of hepatocellular carcinoma(HCC)using a combination of propagation-based phase-contrast computed tomography(PPCT),scanning transmission soft X-ray microscopy(STXM),and Fourier transform infrared micro-spectroscopy(FTIR).Our experimental results reveal the trans-scale micro-morpho-logical HCC pathology and facilitate quantitative data analysis and comprehensive assessment.These results include some visualization features of PPCT-based tissue microenvironments,STXM-based cellular fine structures,and FTIR-based bio-macromolecular spectral characteris-tics during HCC tumor differentiation and proliferation.The proposed method provides multidimensional feature data support for constructing a high-accuracy machine learning algorithm based on a gray-level histogram,gray-gradient co-occurrence matrix,gray-level co-occurrence matrix,and back-propagation neural network model.Multi-dimensional information analysis and diagnosis revealed the morphological pathways of HCC pathological evolution and we explored the relationships between HCC-related feature changes in inflammatory microenviron-ments,cellular metabolism,and the stretching vibration peaks of biomolecules of lipids,proteins,and nucleic acids.Therefore,the proposed methodology has strong potential for the visualization of complex tumors and assessing the risks of tumor differentiation and metastasis.
基金supported in part by the National Key R&D Program of China(Nos.2020YFA0405800,2022YFA1504104,and 2022YFA1605400)the National Natural Science Foundation of China(Nos.12225508,12322515,U1932201,U2032113,and 22075264)+5 种基金the Youth Innovation Promotion Association of CAS(No.2022457)the Institute of Energy,Hefei Comprehensive National Science Center,University Synergy Innovation Program of Anhui Province(No.GXXT-2020-002)and the CAS Iterdisciplinary Innovation Team.We thank the Shanghai Synchrotron Radiation Facility(BL14W1,BL14B1,and SSRF)the Beijing Synchrotron Radiation Facility(1W1B,4B7A,and BSRF)the Hefei Synchrotron Radiation Facility(Infrared Spectroscopy and Microspectroscopy,MCD-A and MCD-B Soochow Beamline for Energy Materials at NSRL)and the USTC Center for Micro and Nanoscale Research and Fabrication for helps in characterizations.
文摘Breakthroughs in energy storage and conversion devices depend heavily on the exploration of low-cost and high-performance materials.Carbon-supported electrocatalysts with dimensional varieties have recently attracted significant attention due to their strong structural flexibility and easy accessibility.Nevertheless,understanding the connection between their electronic,structural properties,and catalytic performance must remain a top priority.Synchrotron radiation(SR)X-ray absorption spectroscopy(XAS)techniques,including hard XAS and soft XAS,are recognized as efficient and comprehensive platforms for probing the surface,interface,and bulk electronic structure of elements of interest in the materials community.In the past decade,the flourishing development of materials science and advanced characterization technologies have led to a deeper understanding at different temporal,longitudinal,and spatial scales.In this review,we briefly describe the concept of XAS techniques and summarize their recent progress in addressing scientific questions on carbon-supported electrocatalysts through the development of advanced instruments and experimental methods.We then discuss the remaining challenges and potential research directions in nextgeneration materials frontiers,and suggest challenges and perspectives for shedding light on the structure–activity relationship.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40774098 and 10878004)
文摘In this paper we have reviewed our achievements in soft X-ray and extreme ultraviolet (EUV) optics. Up to now, the research system of soft X-ray and EUV optics has been established, including light sources, detectors, calibrations, optical testing and machining of super smooth mirrors, and fabrications of multilayer film mirrors. Based on our achievements, we have developed two types of solar space telescopes for the soft X-ray and EUV space solar observations. One is an EUV multilayer normal incident telescope array including 4 different operation wavelength telescopes. The operation wavelengths of the EUV telescope are 13.0, 17.1, 19.5 and 30.4 nm. The other is a complex space solar telescope, which is composed of an EUV multilayer normal incident telescope and a soft X-ray grazing incident telescope. The EUV multilayer normal incident telescope stands in the central part of the soft X-ray grazing incident telescope. The normal incident telescope and the grazing incident telescope have a common detector. The different operation wavelengths can be changed by rotating a filter wheel.
基金This work was supported by the National Natural Science Foundation of China(NSFC,Nos.21801140,51532001,51667009,21771014,and 52002010)。
文摘Nickel based magnetic nanocrystals have been widely applied in magnetic and catalytic facilities.Tunable magnetic properties of nickel can be easily obtained via non-magnetic doping or phase transformation.However,phase transformation from face centered cubic(fcc)to hexagonal close packed(hcp)induced magnetism adjustment of Ni are always confused with nickel carbide(Ni_(3)C),due to the similar atomic structures of hcp-Ni and Ni3C.Here,we present series of Au@Ni-carbide magnetic materials achieved from the controlled carbonation of Au@Ni core-shell structures,whose magnetism is tunable by adjusting the amount of carbon in the Ni layer.Ex-situ hard X-ray absorption spectroscopy(XAS)at the metal K edge and soft XAS at both metal L edge and carbon K edge provide solid evidence for the carbonation process from fcc-Ni to Ni_(x)C,rather than phase transformation to hcp-Ni.Further investigation reveals that the magnetism of the hybrids is mainly contributed from the residual fcc-Ni.The result represents an accurate and effective way to distinguish hexagonal Ni_(3)C from hcp-Ni,and provides the pathway to control magnetism of Ni-based materials for applications.
基金supported by the National Natural Science Foundation of China(No.51976209)the Fundamental Research Funds for the Central Universities(No.WK2320000040)+1 种基金the Synchrotron Radiation Joint Fund of University of Science and Technology of Chinasupported by Youth Innovation Promotion Association CAS(No.Y201768)。
文摘By virtue of the crucial effect of the crystal structure and transition metal(TM)redox evolution on the performance of LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM)cathode,systematical investigation is carried out to better understand the charge mechanism upon deep charging.Based on the results of X-ray diffraction and highresolution transmission electron microscope,phase transformations existing on particle surface are promoted by high potential because of the deeper lithium vacancies,accompanied by more substantial structure instability.Soft X-ray absorption spectroscopy indicates that Ni acts as the major contributor to charge compensation while Co displays a remarkable redox activity over the deep charge range.The elevated integrated intensity of pre-edge in O K-edge spectra reveals the extensive amount of holes formed in O 2 p orbitals and the enhanced hybridization of TM 3 d-O 2 p orbitals.Considering the close relationship between thermal behavior and structural evolution,the tendency of phase transitions and O_(2) release upon heating is accelerated by voltage rise,demonstrating the aggravated instability due to deeper Li utilization.Remaining Li contents in NCM are employed to estimate the amount of oxygen released in structural transformation and its detrimental effect on stability declares Li contentdependent characteristics.Furthermore,the extended Li vacancies,higher proportion of Ni4+and stronger orbital hybridization are considered as three factors impeding the thermal stability of the highlydelithiated NCM.
基金This work was financially supported in part by the National Key R&D Program of China(Nos.2017YFA0303500 and 2020YFA0405800)National Natural Science Foundation of China(NSFC)(Nos.U1932201,U2032113,and 22075264)+3 种基金CAS Collaborative Innovation Program of Hefei Science Center(Nos.2019HSC-CIP002 and 2020HSC-CIP002)the USTC Start-Up Fund,and CAS Interdisciplinary Innovation TeamL.S.acknowledges the support from Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education)Nankai University(111 projects,B_(12)015).
文摘Despite acknowledgment of structural reconstruction of materials following oxygen evolution reaction (OER) reaction, the role of support during the reconstruction process has been ignored. Given this, we directly in situ transform the residual iron present in raw single-walled carbon nanotubes (SWCNT) into Fe_(2)O_(3) and thus build Fe_(2)O_(3)-CNT as the model system. Intriguingly, an anomalous self-optimization occurred on SWCNT and the derived components show satisfactory electrochemical performance. Soft X-ray absorption spectroscopy (sXAS) analysis and theory calculation correspondingly indicate that self-optimization yields stronger interaction between SWCNT and Fe_(2)O_(3) nanoparticles, where the electrons migrate from Fe_(2)O_(3) to optimized SWCNT. Such polarization will generate a positive charge center and thus boost the OER activity. This finding directly observes the self-optimization of support effect, providing a new perspective for OER and related electrochemical reactions.
基金This work was financially supported by the National Natural Science Foundation of China(31801262 and 31871523)National Key Research and Development Program of China(2018YFD0101004).
文摘Over the past decades,imaging and spectroscopy techniques have been developed rapidly with widespread applications in non-destructive agro-food quality determination.Seeds are one of themost fundamental elements of agriculture and forestry.Seed viability is of great significance in seed quality characteristics reflecting potential seed germination,and there is a great need for a quick and effective method to determine the germination condition and viability of seeds prior to cultivate,sale and plant.Some researches based on spectra and/or image processing and analysis have been explored in terms of the external and internal quality of a variety of seeds.Many attempts have been made in image segmentation and spectra correction methods to predict seed quality using various traditional and novel methods.This review focuses on the comparative introduction,development and applications of emerging techniques in the analysis of seed viability,in particular,near infrared spectroscopy,hyperspectral and multispectral imaging,Raman spectroscopy,infrared thermography,and soft X-ray imaging methods.The basic theories,principle components,relative chemometric processing,analytical methods and prediction accuracies are reported and compared.Additionally,on the foundation of the observed applications,the technical challenges and future outlook for these emerging techniques are also discussed.