Computational spectrometers utilizing disordered structures have emerged as promising solutions for meeting the imperative demand for integrated spectrometers,offering high performance and improved resilience to fabri...Computational spectrometers utilizing disordered structures have emerged as promising solutions for meeting the imperative demand for integrated spectrometers,offering high performance and improved resilience to fabrication variations and temperature fluctuations.However,the current computational spectrometers are impractical because they rely on a brute-force random design approach for disordered structures.This leads to an uncontrollable,non-reproducible,and suboptimal spectrometer performance.In this study,we revolutionize the existing paradigm by introducing a novel inverse design approach for computational spectrometers.By harnessing the power of inverse design,which has traditionally been applied to optimize single devices with simple performance,we successfully adapted it to optimize a complex system comprising multiple correlated components with intricate spectral responses.This approach can be applied to a wide range of structures.We validated this by realizing a spectrometer utilizing a new type of disordered structure based on interferometric effects that exhibits negligible loss and high sensitivity.For a given structure,our approach yielded a remarkable 12-times improvement in the spectral resolution and a four-fold reduction in the cross-correlation between the filters.The resulting spectrometer demonstrated reliable and reproducible performance with the precise determination of structural parameters.展开更多
An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulatio...An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulations and careful mechanical designs,a shielding configuration has been successfully developed to satisfy safety requirements of below 3μSv/h dose rate at its exterior,meanwhile fulfilling space,floor load and nonmagnetic requirements.Composite materials are utilized to form the sandwich-type shielding walls:the inner layer of boron carbide rubber,the middle layer of steel-encased lead and the outer layer of borated polyethylene.Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage.Our work has demonstrated that by utilizing composite shielding materials,along with the sandwich structure and liftable shielding blocks,a compact and lightweight shielding solution can be achieved.This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement,larger energy and momentum coverage,and higher flux on the sample.This shielding represents the first of its kind in neutron scattering instruments in China.Following its successful operation,it has been subsequently employed by other neutron instruments across the country.展开更多
With outstanding analytical performance and portability, miniature mass spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass spectrometers has lasted for more than ten years...With outstanding analytical performance and portability, miniature mass spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass spectrometers has lasted for more than ten years, during which a number of miniature mass spectrometers employing different techniques have been developed. Small-in-size, working at relatively high pressure region and capable of performing tandem mass spectrometry, ion trap is the most widely used mass analyzer in miniature mass spectrometer systems. The recent development of miniature ion trap mass spectrometer systems in the last ten years was reviewed in this paper. These instruments adopt different atmospheric pressure interfaces （APIs）, which are membrane inlets （MIs）, discontinuous atmospheric pressure interface （DAPI） and continuous atmospheric pressure interface （CAPI）. This review emphasizes on the mini mass spectrometry （MS） system that can be handheld by one person, but not the field-able ones that are too large to be hand-portable.展开更多
Two different aerosol mass spectrometers, Aerodyne Aerosol Mass Spectrometer（AMS） and Single Particle Aerosol Mass Spectrometer（SPAMS） were deployed to identify the aerosol pollutants over Xiamen, representing the...Two different aerosol mass spectrometers, Aerodyne Aerosol Mass Spectrometer（AMS） and Single Particle Aerosol Mass Spectrometer（SPAMS） were deployed to identify the aerosol pollutants over Xiamen, representing the coastal urban area. Five obvious processes were classified during the whole observation period. Organics and sulfate were the dominant components in ambient aerosols over Xiamen. Most of the particles were in the size range of 0.2–1.0 μm, accounting for over 97% of the total particles measured by both instruments.Organics, as well as sulfate, measured by AMS were in good correlation with measured by SPAMS. However, high concentration of NH4＋was obtained by AMS, while extremely low value of NH4＋was detected by SPAMS. Contrarily, high particle number counts of NO3-and Clwere given by SPAMS while low concentrations of NO3-and Cl-were measured by AMS. The variations of POA and SOA obtained from SPAMS during event 1 and event 2 were in accordance with the analysis of HOA and OOA given by AMS, suggesting that both of AMS and SPAMS can well identify the organic clusters of aerosol particles. Overestimate or underestimate of the aerosol sources and acidity would be present in some circumstances when the measurement results were used to analyze the aerosol properties, because of the detection loss of some species for both instruments.展开更多
Data from abnormal channels in an imaging spectrometer almost always exerts an undesired impact on spectrum matching,classification,pattern recognition and other applications in hyperspectral remote sensing.To solve t...Data from abnormal channels in an imaging spectrometer almost always exerts an undesired impact on spectrum matching,classification,pattern recognition and other applications in hyperspectral remote sensing.To solve this problem,researchers should get rid of the data acquired by these channels.Selecting abnormal channels just in the way of visually examining each band image in a imaging data set is a conceivably hard and boring job.To relieve the burden,this paper proposes a method which exploits the spatial and spectral autocorrelations inherent in imaging spectrometer data,and can be used to speed up and,to a great degree,automate the detection of abnormal channels in an imaging spectrometer.This method is applied easily and successfully to one PHI data set and one Hymap data set,and can be applied to remotely sensed data from other hyperspectral sensors.展开更多
A normal incidence vacuum ultraviolet （VUV） and a grazing incidence extreme ultraviolet （EUV） spectrometers have been developed for the edge and core impurity measure- ments in HL-2A tokamak. The VUV and the EUV s...A normal incidence vacuum ultraviolet （VUV） and a grazing incidence extreme ultraviolet （EUV） spectrometers have been developed for the edge and core impurity measure- ments in HL-2A tokamak. The VUV and the EUV spectrometers cover wavelength ranges of 300-3200 A and 50-500A, respectively. A spatial resolution of 2 mm has been achieved for the VUV spectrometer when a space-resolved slit 50 #m in width is used. The space-resolved slit is placed between the entrance slit and the grating of the spectrometer. The spectral resolutions of 0.15/~ for the VUV spectrometer in the wavelength coverage of the concave 1200 grooves/mm grating and of 0.22A for the EUV spectrometer at λ=200A with a flat-field laminar-type holo- graphic grating are obtained. The sensitivity of the VUV spectrometer was calibrated in situ with the plasma bremsstrahlung radiation. The experimental results from both spectrometers are presented, especially the line intensity radial profiles measured by the VUV spectrometer.展开更多
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 cry...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.展开更多
The miniaturization of spectrometer opens a new application area with real-time and on-site measurements.The Fourier transform spectrometer(FTS)is much attractive considering its particular advantages among the approa...The miniaturization of spectrometer opens a new application area with real-time and on-site measurements.The Fourier transform spectrometer(FTS)is much attractive considering its particular advantages among the approaches.This paper reviews the current status of micro FTS in worldwide and describes its developments;In addition,analyzed are the key problems in designing and fabricating FTS to be settled during the miniaturization.Finally,a novel model of micro FTS with no moving parts is proposed and analyzed,which may provide new concepts for the design of spectrometers.展开更多
Microsatellites have recently opened windows of frequent and low cost missions for planetary exploration. The performance of gamma-ray and neutron spectrometers on future microsatellite missions is simulated to assess...Microsatellites have recently opened windows of frequent and low cost missions for planetary exploration. The performance of gamma-ray and neutron spectrometers on future microsatellite missions is simulated to assess the possibility of observation of hydrogen and major elements, given their concentration on the observation target. The measured elemental abundance will provide important geological constraints, and some of them may serve as space resources. Four different types of target bodies with various hydrogen concentrations in the range of 0 - 20,000 ppm are assumed as target compositions;Earth’s core, C-type, S-type and Martian meteorites. Gamma-ray and neutron emission rates show unique footprints that are related to the different elemental compositions. The starting point is the solid angle subtended between observation target and spectrometers that allow estimating the gamma-ray and neutron count rates emitted by the celestial bodies. In this work, three types of gamma-ray detectors;high-purity germanium (HPGe), CeBr3 and LaBr3(Ce), a neutron spectrometer combining a lithium glass scintillator with a boron loaded plastic scintillator and a dual mode spectrometer Cs2LiYCl6(Ce) (CLYC) are simulated, focusing on their observation backgrounds as a model case for microsatellite based measurements. The background count level of both gamma-ray (except for the LaBr3 detector) and neutron count rates was negligible under these particular conditions. The gamma-ray detectors were compared by the figure of merit, which was determined by their efficiency and energy resolution. It was found that each detector has unique advantages. The HPGe detector has the highest figure of merit due to its excellent energy resolution, whereas the CLYC detector is low in weight and power consumption due to its dual sensitivity to gamma-ray and neutron. The CeBr3 detector is an intermediate choice. The neutron count rates are calculated separately in three energy ranges, i.e. , thermal (<0.5 eV), epithermal (0.5 eV - 500 keV), and fast (>500 keV), as a function of the hydrogen concentration in the 0 - 20,000 ppm range. The thermal and epithermal neutron count rates are found to decrease with hydrogen concentration, while the fast neutron count rate increases with the target average atomic mass. The optimal detector should be decided by the mission restraints on mass, power consumption, and heat thermal design.展开更多
The ground-based continuous hyperspectral remote sensing technique presents a unique opportunity to advance terrestrial ecosystem monitoring.Accurate retrieval of solar-induced chlorophyll fluorescence(SIF)relies heav...The ground-based continuous hyperspectral remote sensing technique presents a unique opportunity to advance terrestrial ecosystem monitoring.Accurate retrieval of solar-induced chlorophyll fluorescence(SIF)relies heavily on commercially available spectrometers with high spectral resolution(SR).However,high-SR spectrometers are resource-intensive and challenging to maintain,limiting their widespread deployment at observational sites.Here,we explored an alternative low-configuration and low-cost spectrometer for SIF retrieval at 2 sites cultivated with wheat and rice.The results revealed the strong correlations between irradiance and radiance measurements in the selected SIF bands from the high-and low-configuration spectrometers(R^(2)>0.90,average root mean square error<8.95 mW m^(−2) nm^(−1) sr^(−1),relative root mean square error<7%).Far-red SIF retrieved from both spectrometers exhibited marked correlations at both half-hourly and daily averaged scales(R^(2)>0.90).Additionally,we utilized simulated data to examine the impact of SR and signal-to-noise ratio(SNR)on the far-red SIF retrieval from both high-and low-configuration spectrometers.Strong correlations(R^(2)>0.80)were found between the simulated data with SNR≥300 and SR<2 nm.Furthermore,we investigated the relationships between crop gross primary productivity(GPP)and far-red SIF from both types of spectrometers and their ability to identify crop growth stages.SIF from both types of spectrometers exhibited high correlations with GPP(R^(2)>0.70).The dates of various wheat-specific growth stages observed using the low-configuration spectrometer were consistent with those identified by the high-configuration spectrometer,with less than a 3-d differences for wheat.Our study confirms the capabilities of the low-configuration spectrometers for far-red SIF retrievals and promotes their deployment over large-scale ground observation networks,potentially advancing the large development of low-cost ground-based SIF measurements.展开更多
Optical spectrum analysis provides a wealth of information about the physical world.Throughout the development of optical spectrum analysis,sensitivity has been one of the major topics and has become essential in appl...Optical spectrum analysis provides a wealth of information about the physical world.Throughout the development of optical spectrum analysis,sensitivity has been one of the major topics and has become essential in applications dealing with faint light.Various high-sensitivity optical detection technologies have been applied in optical spectrum analysis to enhance its sensitivity to single-photon level.As an emerging single-photon detection technology,superconducting nanowire single-photon detectors(SNSPDs)have many impressive features such as high detection efficiency,broad operation bandwidth,small timing jitter,and so on,which make them promising for enhancing the performance of optical spectral analysis.Diverse schemes for photon-counting spectrometers based on SNSPDs have been demonstrated.This article reviews these impressive works and prospects for the future development of this technology.Further breakthroughs can be expected in its theories,device performance,applications,and combinations with in-sensor computing,promoting it to be a mature and versatile solution for optical spectrum analysis on ultra-faint light.展开更多
The Macao Science Satellite-1 is a two-satellite constellation specifically designed to study the geomagnetic field and particle radiation environment in low Earth orbit,particularly in the South Atlantic Anomaly regi...The Macao Science Satellite-1 is a two-satellite constellation specifically designed to study the geomagnetic field and particle radiation environment in low Earth orbit,particularly in the South Atlantic Anomaly region,with a low inclination orbit.Each of the two MSS-1 satellites carries a medium-energy electron spectrometer(MES).The MES sensor heads are based on pinhole imaging technology,which can simultaneously measure 50-600 keV electrons incident from nine directions with a field of view(FOV)of 180°×30°.The two MESs can realize the pitch angle coverage of medium energy electrons at most positions in the orbit.The MSS-1 A/B MESs can realize direct observation of precipitating electrons and electrons near their loss cones.It can help to study the electron generation mechanism in the inner radiation belt and quantify the precipitation of magnetospheric energetic electrons.Combined with the geomagnetic index,solar wind parameters,interplanetary magnetic field conditions,etc.,it can also help to build a dynamic evolution model of energetic electrons in the near-Earth space,to realize the early warning and prediction of space weather based on the observation data,which can provide safety for spacecraft and astronauts in the nearEarth space.展开更多
In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources i...In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources introduce complexity.Specifically,these discrepancies can cause variations in the intensities of the characteristic spectral lines emitted by identical elements.These variations,compounded by the minimal energy spacing between these spectral lines,pose substantial challenges for conventional silicon drift detectors(SDD),hindering their ability to accurately differentiate these lines and provide detailed insights into the material structure.To overcome this challenge,a cryogenic X-ray spectrometer based on transition-edge sensor(TES)detector arrays is required to achieve precise measurements.This study measured and analyzed the K-edge characteristic lines of copper and the diverse L-edge characteristic lines of tungsten using a comparative analysis of the electron and X-ray excitation processes.For the electron excitation experiments,copper and tungsten targets were employed as X-ray sources,as they emit distinctive X-ray spectra upon electron-beam bombardment.In the photon excitation experiments,a molybdenum target was used to produce a continuous spectrum with the prominent Mo Kαlines to emit pure copper and tungsten samples.TES detectors were used for the comparative spectroscopic analysis.The initial comparison revealed no substantial differences in the Kαand Kβlines of copper across different excitation sources.Similarly,the Lαlines of tungsten exhibited uniformity under different excitation sources.However,this investigation revealed pronounced differences within the Lβline series.The study found that XRF spectra preferentially excite outer-shell electrons,in contrast to intrinsic spectra,owing to different photon and electron interaction mechanisms.Photon interactions are selection-ruledependent and involve a single electron,whereas electron interactions can involve multiple electrons without such limitations.This leads to varied excitation transitions,as evidenced in the observed Lβline series.展开更多
Bandgap-graded materials present varying spectral responses at different positions,making them possible to be used as an alternative to photoactive materials array in multi-spectral responsive devices,thus miniaturizi...Bandgap-graded materials present varying spectral responses at different positions,making them possible to be used as an alternative to photoactive materials array in multi-spectral responsive devices,thus miniaturizing the apparatus.However,the preparation of bandgap-graded materials usually requires complicated deposition process.Here we report a facile lowtemperature solution process to make films with lateral bandgap gradients,which form spontaneously via self-spreading and interdiffusion of solutions.We show lead halide perovskite films with MAPbCl_(3)-MAPbBr_(3)and MAPbBr_(3)-MAPbI_(3)gradients,which exhibit light absorption onsets ranging from 410 to 781 nm.The bandgap-graded films were used to make self-powered multiband photodetectors,which show different spectral responses at different positions without applying bias voltage.Furthermore,self-powered spectrometers were made by using the multiband photodetectors.展开更多
Integrating exhaled breath analysis into the diagnosis of cardiovascular diseases holds significant promise as a valuable tool for future clinical use,particularly for ischemic heart disease(IHD).However,current resea...Integrating exhaled breath analysis into the diagnosis of cardiovascular diseases holds significant promise as a valuable tool for future clinical use,particularly for ischemic heart disease(IHD).However,current research on the volatilome(exhaled breath composition)in heart disease remains underexplored and lacks sufficient evidence to confirm its clinical validity.Key challenges hindering the application of breath analysis in diagnosing IHD include the scarcity of studies(only three published papers to date),substantial methodological bias in two of these studies,and the absence of standardized protocols for clinical imple-mentation.Additionally,inconsistencies in methodologies—such as sample collection,analytical techniques,machine learning(ML)approaches,and result interpretation—vary widely across studies,further complicating their reprodu-cibility and comparability.To address these gaps,there is an urgent need to establish unified guidelines that define best practices for breath sample collection,data analysis,ML integration,and biomarker annotation.Until these challenges are systematically resolved,the widespread adoption of exhaled breath analysis as a reliable diagnostic tool for IHD remains a distant goal rather than an immi-nent reality.展开更多
The method for synthesis of corrected three-wavelengths spectrometers for trace gas components of atmo- sphere on the basis of development of mathematical model has been suggested. The classification table for possibl...The method for synthesis of corrected three-wavelengths spectrometers for trace gas components of atmo- sphere on the basis of development of mathematical model has been suggested. The classification table for possible structures of corrected spectrometers is considered. The synthesis allows to reveal some new variants for development of three-wavelength spectrometers for trace gas components of atmosphere. For experimental checkup of achieved theoretical results, a laboratory pattern of three-wavelength spectrome- ter is developed and tested.展开更多
Water-soluble organic aerosol(WSOA)plays a significant role in air quality and human health.Here we characterized the chemical properties and molecular compositions of WSOA at a rural site in North China Plain during ...Water-soluble organic aerosol(WSOA)plays a significant role in air quality and human health.Here we characterized the chemical properties and molecular compositions of WSOA at a rural site in North China Plain during winter using a high-resolution aerosol mass spectrometer and electrospray ionization high-resolution orbitrap mass spectrometer(ESI-HRMS).Our results show that the mass concentration of WSOA was significantly higher than that observed in Beijing in winter 2020,contributing about 56%of OA on average.CHO compounds(56%-74%)and CHN compounds(66%-80%)dominated in negative mode and positive mode,respectively,while CHON accounted for 15%-41%across both modes.The chemical characteristics of WSOA varied with polluted levels and between day and night.As pollution intensified,the abundance of CHO-compounds with condensed aromatics increased by 9%and the number of highly oxygenated molecules(HOMs)molecular formula detected in server haze was more than double that of clean days.CHO-compounds with ten carbon atoms(C_(10))were more abundant at night while those with nine carbon atoms(C_(9))were higher during the day.High levels of CHN+compounds were linked to nighttime biomass burning,whereas CHON compounds were more abundant during the day.Increased pollution also led to the formation of more complex CHON-compounds,indicating that organonitrates continue to play a significant role in rural pollution.展开更多
Particulate levoglucosan is an important tracer for biomass burning emission in ambient air.However,recent studies question its reliability as a biomass burning tracer in Chinesemega cities due to important contributi...Particulate levoglucosan is an important tracer for biomass burning emission in ambient air.However,recent studies question its reliability as a biomass burning tracer in Chinesemega cities due to important contribution from potential non-biomass burning sources,such as cooking.To address this,we examined the dynamic variation and sources of levoglucosan using a chemical ionization mass spectrometer and other advanced instruments during Beijing’s summer of 2021.The average mass concentration of levoglucosan and its isomer(C_(6)H_(10)O_(5))was 0.025±0.014μg/m^(3),constituting 0.55%±0.32%of total organic carbon(OC)in this campaign.Despite cooking emissions contributing significantly to the organic aerosol(OA,20%),levoglucosan and its isomers correlated more strongly with biomass-burning related tracers(R>0.6),black carbon(R=0.72)and less so with cooking-related sources(R=0.3).This indicates that levoglucosan is primarily dominated by biomass-burning emissions rather than cooking in Beijing’s urban areas during summertime.The diurnal variation of levoglucosan concentrations highlighted the importance of daytime and nocturnal biomass burning emissions during polluted periods in Beijing.Using levoglucosan as a tracer to quantify the biomass burning OC(BBOC),we found good agreement on the time series of BBOC between the tracermethod and other independent source apportionmentmethod.This reaffirms the reliability of levoglucosan as a biomass burning tracer.Biomass burning contributed an average of 7%-8%to OC,highlighting its significant impact on Beijing’s summer air quality.Our study enhances understanding of biomass burning influences on ambient aerosol in typical urban areas.展开更多
Soil erosion is one of the major global hazards threatening the food security of the world population.Soil erosion can be a result of both natural and anthropogenic processes.Field monitoring and models(numerical and ...Soil erosion is one of the major global hazards threatening the food security of the world population.Soil erosion can be a result of both natural and anthropogenic processes.Field monitoring and models(numerical and physical)are commonly used to quantify soil erosion.However,field methods are time-consuming and the models inherently work with a level of uncertainty.Soil erosion studies in the Himalayas have been mostly carried out using modelling but there is a lack of sufficient field data to validate the results.We quantified soil erosion in a small catchment(Pranmati)in the Himalayas using the fallout meteoric^(10)Be nuclide for the first time.Based on the^(10)Be flux delivery rates determined from global circulation models(GCM),we calculated the rates of soil erosion at discrete points in the hilltop and mid-slope regions of hillslopes.The erosion rates vary between 17 mm kyr^(-1)to 68 mm kyr^(-1).These rates were determined in pristine areas that are unaffected by anthropogenic activities,thus,indicate the background erosion rates in the region.We established empirical relationships with estimated erosion rates and topographic parameters to assess the sediment dynamics in the hillslopes.It was observed that the sediment redistribution process operates differently in the mid-slope region compared to the hilltop region,due to increasing complexity of the active processes in the mid-slope region.展开更多
Warm dense plasmas are crucial for high-energy-density physics and inertial confinement fusion research.Experiments involving laser-irradiated copper(Cu)foil were performed at the Shenguang-II facility.A highly orient...Warm dense plasmas are crucial for high-energy-density physics and inertial confinement fusion research.Experiments involving laser-irradiated copper(Cu)foil were performed at the Shenguang-II facility.A highly oriented pyrolytic graphite crystal spectrometer measured the time-integrated spectral distribution of Cu under varying laser intensities.Using the two-dimensional radiation-hydrodynamics code FLASH and the spectral analysis code FLYCHK,we simulated the temporal evolution of plasma density and temperature distributions,as well as the emission intensities of spectral lines at different temperatures and densities.The simulation results revealed that the two-electron satellite lines(J)and the resonance line(W)emissions of Cu originate predominantly from the radiation region near the critical density surface,with a density range from approximately 0.5 nc to 1.0 nc,and radiate primarily during the laser irradiation period.By analyzing the J/W intensity ratio of the measured spectral lines,we estimated the electron temperatures near the critical-density surface under different laser intensities.展开更多
基金supported by National Key Research and Development Program of China(2021YFB2801500,2022YFB3206001,and 2023YFB3405600)National Natural Science Foundation of China(62375126,62105149,and 62334001)+2 种基金the Leading Innovation and Entrepreneurship Team Project in Zhejiang(2022R01001)Key Laboratory of Modern Optical Technologies of Education Ministry of China,Soochow UniversityState Key Laboratory of Advanced Optical Communication Systems and Networks,China。
文摘Computational spectrometers utilizing disordered structures have emerged as promising solutions for meeting the imperative demand for integrated spectrometers,offering high performance and improved resilience to fabrication variations and temperature fluctuations.However,the current computational spectrometers are impractical because they rely on a brute-force random design approach for disordered structures.This leads to an uncontrollable,non-reproducible,and suboptimal spectrometer performance.In this study,we revolutionize the existing paradigm by introducing a novel inverse design approach for computational spectrometers.By harnessing the power of inverse design,which has traditionally been applied to optimize single devices with simple performance,we successfully adapted it to optimize a complex system comprising multiple correlated components with intricate spectral responses.This approach can be applied to a wide range of structures.We validated this by realizing a spectrometer utilizing a new type of disordered structure based on interferometric effects that exhibits negligible loss and high sensitivity.For a given structure,our approach yielded a remarkable 12-times improvement in the spectral resolution and a four-fold reduction in the cross-correlation between the filters.The resulting spectrometer demonstrated reliable and reproducible performance with the precise determination of structural parameters.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12004426,U2030106,and 12304185)the National Key Scientific Instrument and Equipment Development Project of NSFC(Grant No.11227906)the National Key R&D Program of China(Grant No.2023YFA1406500)。
文摘An innovative monochromator shielding is designed and implemented for the cold neutron spectrometers XINGZHI and BOYA operated by Renmin University of China at China Advanced Research Reactor.Via Monte Carlo simulations and careful mechanical designs,a shielding configuration has been successfully developed to satisfy safety requirements of below 3μSv/h dose rate at its exterior,meanwhile fulfilling space,floor load and nonmagnetic requirements.Composite materials are utilized to form the sandwich-type shielding walls:the inner layer of boron carbide rubber,the middle layer of steel-encased lead and the outer layer of borated polyethylene.Special-shaped liftable shielding blocks are incorporated to facilitate a continuous adjustment of the neutron energy while preventing radiation leakage.Our work has demonstrated that by utilizing composite shielding materials,along with the sandwich structure and liftable shielding blocks,a compact and lightweight shielding solution can be achieved.This enables the realization of advanced neutron scattering instruments that provide expanded space of measurement,larger energy and momentum coverage,and higher flux on the sample.This shielding represents the first of its kind in neutron scattering instruments in China.Following its successful operation,it has been subsequently employed by other neutron instruments across the country.
基金supported by the National Natural Science Foundation of China (Nos. 21475010, 61635003)Beijing Natural Science Foundation (No. 16L00065)State Key Laboratory Explosion Science and Technology (No. YBKT16-17)
文摘With outstanding analytical performance and portability, miniature mass spectrometer is one of the most powerful tools for in-situ analysis. The miniaturization of mass spectrometers has lasted for more than ten years, during which a number of miniature mass spectrometers employing different techniques have been developed. Small-in-size, working at relatively high pressure region and capable of performing tandem mass spectrometry, ion trap is the most widely used mass analyzer in miniature mass spectrometer systems. The recent development of miniature ion trap mass spectrometer systems in the last ten years was reviewed in this paper. These instruments adopt different atmospheric pressure interfaces （APIs）, which are membrane inlets （MIs）, discontinuous atmospheric pressure interface （DAPI） and continuous atmospheric pressure interface （CAPI）. This review emphasizes on the mini mass spectrometry （MS） system that can be handheld by one person, but not the field-able ones that are too large to be hand-portable.
基金supported by the Natural Science Foundation of Fujian Province,China(No.2015J05024)financially supported by Qingdao National Laboratory for marine science and technology(No.QNLM2016ORP0109)+2 种基金the National Natural Science Foundation of China(No.21106018,No.41305133)the Scientific Research Foundation of Third Institute of Oceanography,SOA(No.2014027)the Special Fund for Marine Researches in the Public Interest(No.2004DIB5J178)
文摘Two different aerosol mass spectrometers, Aerodyne Aerosol Mass Spectrometer（AMS） and Single Particle Aerosol Mass Spectrometer（SPAMS） were deployed to identify the aerosol pollutants over Xiamen, representing the coastal urban area. Five obvious processes were classified during the whole observation period. Organics and sulfate were the dominant components in ambient aerosols over Xiamen. Most of the particles were in the size range of 0.2–1.0 μm, accounting for over 97% of the total particles measured by both instruments.Organics, as well as sulfate, measured by AMS were in good correlation with measured by SPAMS. However, high concentration of NH4＋was obtained by AMS, while extremely low value of NH4＋was detected by SPAMS. Contrarily, high particle number counts of NO3-and Clwere given by SPAMS while low concentrations of NO3-and Cl-were measured by AMS. The variations of POA and SOA obtained from SPAMS during event 1 and event 2 were in accordance with the analysis of HOA and OOA given by AMS, suggesting that both of AMS and SPAMS can well identify the organic clusters of aerosol particles. Overestimate or underestimate of the aerosol sources and acidity would be present in some circumstances when the measurement results were used to analyze the aerosol properties, because of the detection loss of some species for both instruments.
文摘Data from abnormal channels in an imaging spectrometer almost always exerts an undesired impact on spectrum matching,classification,pattern recognition and other applications in hyperspectral remote sensing.To solve this problem,researchers should get rid of the data acquired by these channels.Selecting abnormal channels just in the way of visually examining each band image in a imaging data set is a conceivably hard and boring job.To relieve the burden,this paper proposes a method which exploits the spatial and spectral autocorrelations inherent in imaging spectrometer data,and can be used to speed up and,to a great degree,automate the detection of abnormal channels in an imaging spectrometer.This method is applied easily and successfully to one PHI data set and one Hymap data set,and can be applied to remotely sensed data from other hyperspectral sensors.
基金partially supported by National Natural Science Foundation of China (Nos. 10975048 and 11175061)the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics (No. 11261140328)
文摘A normal incidence vacuum ultraviolet （VUV） and a grazing incidence extreme ultraviolet （EUV） spectrometers have been developed for the edge and core impurity measure- ments in HL-2A tokamak. The VUV and the EUV spectrometers cover wavelength ranges of 300-3200 A and 50-500A, respectively. A spatial resolution of 2 mm has been achieved for the VUV spectrometer when a space-resolved slit 50 #m in width is used. The space-resolved slit is placed between the entrance slit and the grating of the spectrometer. The spectral resolutions of 0.15/~ for the VUV spectrometer in the wavelength coverage of the concave 1200 grooves/mm grating and of 0.22A for the EUV spectrometer at λ=200A with a flat-field laminar-type holo- graphic grating are obtained. The sensitivity of the VUV spectrometer was calibrated in situ with the plasma bremsstrahlung radiation. The experimental results from both spectrometers are presented, especially the line intensity radial profiles measured by the VUV spectrometer.
基金partially supported by the National Magnetic Confinement Fusion Science Program of China(No.2015GB103002)Key Program of Research and Development of Hefei Science Center(No.2017HSC-KPRD002)+1 种基金the Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2016FXZY008)the CASHIPS Director’s Funds Grant(No.YZJJ201612)
文摘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.
基金National Natural Science Fundation of China(60578036)
文摘The miniaturization of spectrometer opens a new application area with real-time and on-site measurements.The Fourier transform spectrometer(FTS)is much attractive considering its particular advantages among the approaches.This paper reviews the current status of micro FTS in worldwide and describes its developments;In addition,analyzed are the key problems in designing and fabricating FTS to be settled during the miniaturization.Finally,a novel model of micro FTS with no moving parts is proposed and analyzed,which may provide new concepts for the design of spectrometers.
基金This paper is a part of the outcome research performed under a Waseda University Grant for Special Research Project(Project number:2017B-208).
文摘Microsatellites have recently opened windows of frequent and low cost missions for planetary exploration. The performance of gamma-ray and neutron spectrometers on future microsatellite missions is simulated to assess the possibility of observation of hydrogen and major elements, given their concentration on the observation target. The measured elemental abundance will provide important geological constraints, and some of them may serve as space resources. Four different types of target bodies with various hydrogen concentrations in the range of 0 - 20,000 ppm are assumed as target compositions;Earth’s core, C-type, S-type and Martian meteorites. Gamma-ray and neutron emission rates show unique footprints that are related to the different elemental compositions. The starting point is the solid angle subtended between observation target and spectrometers that allow estimating the gamma-ray and neutron count rates emitted by the celestial bodies. In this work, three types of gamma-ray detectors;high-purity germanium (HPGe), CeBr3 and LaBr3(Ce), a neutron spectrometer combining a lithium glass scintillator with a boron loaded plastic scintillator and a dual mode spectrometer Cs2LiYCl6(Ce) (CLYC) are simulated, focusing on their observation backgrounds as a model case for microsatellite based measurements. The background count level of both gamma-ray (except for the LaBr3 detector) and neutron count rates was negligible under these particular conditions. The gamma-ray detectors were compared by the figure of merit, which was determined by their efficiency and energy resolution. It was found that each detector has unique advantages. The HPGe detector has the highest figure of merit due to its excellent energy resolution, whereas the CLYC detector is low in weight and power consumption due to its dual sensitivity to gamma-ray and neutron. The CeBr3 detector is an intermediate choice. The neutron count rates are calculated separately in three energy ranges, i.e. , thermal (<0.5 eV), epithermal (0.5 eV - 500 keV), and fast (>500 keV), as a function of the hydrogen concentration in the 0 - 20,000 ppm range. The thermal and epithermal neutron count rates are found to decrease with hydrogen concentration, while the fast neutron count rate increases with the target average atomic mass. The optimal detector should be decided by the mission restraints on mass, power consumption, and heat thermal design.
基金the National Natural Science Foundation of China(42125105)the National Key Research and Development Program of China(2022YFF1301900)the Nanjing University Integrated Research Platform of the Ministry of Education-Top Talents Program(090414380033).
文摘The ground-based continuous hyperspectral remote sensing technique presents a unique opportunity to advance terrestrial ecosystem monitoring.Accurate retrieval of solar-induced chlorophyll fluorescence(SIF)relies heavily on commercially available spectrometers with high spectral resolution(SR).However,high-SR spectrometers are resource-intensive and challenging to maintain,limiting their widespread deployment at observational sites.Here,we explored an alternative low-configuration and low-cost spectrometer for SIF retrieval at 2 sites cultivated with wheat and rice.The results revealed the strong correlations between irradiance and radiance measurements in the selected SIF bands from the high-and low-configuration spectrometers(R^(2)>0.90,average root mean square error<8.95 mW m^(−2) nm^(−1) sr^(−1),relative root mean square error<7%).Far-red SIF retrieved from both spectrometers exhibited marked correlations at both half-hourly and daily averaged scales(R^(2)>0.90).Additionally,we utilized simulated data to examine the impact of SR and signal-to-noise ratio(SNR)on the far-red SIF retrieval from both high-and low-configuration spectrometers.Strong correlations(R^(2)>0.80)were found between the simulated data with SNR≥300 and SR<2 nm.Furthermore,we investigated the relationships between crop gross primary productivity(GPP)and far-red SIF from both types of spectrometers and their ability to identify crop growth stages.SIF from both types of spectrometers exhibited high correlations with GPP(R^(2)>0.70).The dates of various wheat-specific growth stages observed using the low-configuration spectrometer were consistent with those identified by the high-configuration spectrometer,with less than a 3-d differences for wheat.Our study confirms the capabilities of the low-configuration spectrometers for far-red SIF retrievals and promotes their deployment over large-scale ground observation networks,potentially advancing the large development of low-cost ground-based SIF measurements.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2806700)the National Natural Science Foundation of China(Grant No.92365210)the Tsinghua Initiative Scientific Research Program,and the project of Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies(JIAOT).
文摘Optical spectrum analysis provides a wealth of information about the physical world.Throughout the development of optical spectrum analysis,sensitivity has been one of the major topics and has become essential in applications dealing with faint light.Various high-sensitivity optical detection technologies have been applied in optical spectrum analysis to enhance its sensitivity to single-photon level.As an emerging single-photon detection technology,superconducting nanowire single-photon detectors(SNSPDs)have many impressive features such as high detection efficiency,broad operation bandwidth,small timing jitter,and so on,which make them promising for enhancing the performance of optical spectral analysis.Diverse schemes for photon-counting spectrometers based on SNSPDs have been demonstrated.This article reviews these impressive works and prospects for the future development of this technology.Further breakthroughs can be expected in its theories,device performance,applications,and combinations with in-sensor computing,promoting it to be a mature and versatile solution for optical spectrum analysis on ultra-faint light.
基金supported by the National Natural Science Foundation of China(Grant No.42274225)the Science and Technology Development Fund,Macao SAR(Grant No.SKL-LPS(MUST)-2024-2026)。
文摘The Macao Science Satellite-1 is a two-satellite constellation specifically designed to study the geomagnetic field and particle radiation environment in low Earth orbit,particularly in the South Atlantic Anomaly region,with a low inclination orbit.Each of the two MSS-1 satellites carries a medium-energy electron spectrometer(MES).The MES sensor heads are based on pinhole imaging technology,which can simultaneously measure 50-600 keV electrons incident from nine directions with a field of view(FOV)of 180°×30°.The two MESs can realize the pitch angle coverage of medium energy electrons at most positions in the orbit.The MSS-1 A/B MESs can realize direct observation of precipitating electrons and electrons near their loss cones.It can help to study the electron generation mechanism in the inner radiation belt and quantify the precipitation of magnetospheric energetic electrons.Combined with the geomagnetic index,solar wind parameters,interplanetary magnetic field conditions,etc.,it can also help to build a dynamic evolution model of energetic electrons in the near-Earth space,to realize the early warning and prediction of space weather based on the observation data,which can provide safety for spacecraft and astronauts in the nearEarth space.
基金supported by the National Key R&D Program of China(No.2022YFF0608303)the National Major Scientific Research Instrument Development Project(No.11927805)+4 种基金the NSFC Young Scientists Fund(No.12005134)the Shanghai-XFEL Beamline Project(SBP)(No.31011505505885920161A2101001)the Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)the Open Fund of the Key Laboratory for Particle Astrophysics and CosmologyMinistry of Education of China。
文摘In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources introduce complexity.Specifically,these discrepancies can cause variations in the intensities of the characteristic spectral lines emitted by identical elements.These variations,compounded by the minimal energy spacing between these spectral lines,pose substantial challenges for conventional silicon drift detectors(SDD),hindering their ability to accurately differentiate these lines and provide detailed insights into the material structure.To overcome this challenge,a cryogenic X-ray spectrometer based on transition-edge sensor(TES)detector arrays is required to achieve precise measurements.This study measured and analyzed the K-edge characteristic lines of copper and the diverse L-edge characteristic lines of tungsten using a comparative analysis of the electron and X-ray excitation processes.For the electron excitation experiments,copper and tungsten targets were employed as X-ray sources,as they emit distinctive X-ray spectra upon electron-beam bombardment.In the photon excitation experiments,a molybdenum target was used to produce a continuous spectrum with the prominent Mo Kαlines to emit pure copper and tungsten samples.TES detectors were used for the comparative spectroscopic analysis.The initial comparison revealed no substantial differences in the Kαand Kβlines of copper across different excitation sources.Similarly,the Lαlines of tungsten exhibited uniformity under different excitation sources.However,this investigation revealed pronounced differences within the Lβline series.The study found that XRF spectra preferentially excite outer-shell electrons,in contrast to intrinsic spectra,owing to different photon and electron interaction mechanisms.Photon interactions are selection-ruledependent and involve a single electron,whereas electron interactions can involve multiple electrons without such limitations.This leads to varied excitation transitions,as evidenced in the observed Lβline series.
基金We thank the National Natural Science Foundation of China(Nos.52203217 and 21961160720)the National Key Research and Development Program of China(No.2022YFB3803300)the Open Research Fund of Songshan Lake Materials Laboratory(No.2021SLABFK02)for financial support.
文摘Bandgap-graded materials present varying spectral responses at different positions,making them possible to be used as an alternative to photoactive materials array in multi-spectral responsive devices,thus miniaturizing the apparatus.However,the preparation of bandgap-graded materials usually requires complicated deposition process.Here we report a facile lowtemperature solution process to make films with lateral bandgap gradients,which form spontaneously via self-spreading and interdiffusion of solutions.We show lead halide perovskite films with MAPbCl_(3)-MAPbBr_(3)and MAPbBr_(3)-MAPbI_(3)gradients,which exhibit light absorption onsets ranging from 410 to 781 nm.The bandgap-graded films were used to make self-powered multiband photodetectors,which show different spectral responses at different positions without applying bias voltage.Furthermore,self-powered spectrometers were made by using the multiband photodetectors.
基金Supported by The government assignment,No.1023022600020-6The Ministry of Science and Higher Education of the Russian Federation Within The Framework of State Support for The Creation and Development of World-Class Research Center“Digital Biodesign and Personalized Healthcare,”No.075-15-2022-304RSF grant,No.24-15-00549.
文摘Integrating exhaled breath analysis into the diagnosis of cardiovascular diseases holds significant promise as a valuable tool for future clinical use,particularly for ischemic heart disease(IHD).However,current research on the volatilome(exhaled breath composition)in heart disease remains underexplored and lacks sufficient evidence to confirm its clinical validity.Key challenges hindering the application of breath analysis in diagnosing IHD include the scarcity of studies(only three published papers to date),substantial methodological bias in two of these studies,and the absence of standardized protocols for clinical imple-mentation.Additionally,inconsistencies in methodologies—such as sample collection,analytical techniques,machine learning(ML)approaches,and result interpretation—vary widely across studies,further complicating their reprodu-cibility and comparability.To address these gaps,there is an urgent need to establish unified guidelines that define best practices for breath sample collection,data analysis,ML integration,and biomarker annotation.Until these challenges are systematically resolved,the widespread adoption of exhaled breath analysis as a reliable diagnostic tool for IHD remains a distant goal rather than an immi-nent reality.
文摘The method for synthesis of corrected three-wavelengths spectrometers for trace gas components of atmo- sphere on the basis of development of mathematical model has been suggested. The classification table for possible structures of corrected spectrometers is considered. The synthesis allows to reveal some new variants for development of three-wavelength spectrometers for trace gas components of atmosphere. For experimental checkup of achieved theoretical results, a laboratory pattern of three-wavelength spectrome- ter is developed and tested.
基金supported by the National Natural Science Foundation of China(No.42307139)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0760200)。
文摘Water-soluble organic aerosol(WSOA)plays a significant role in air quality and human health.Here we characterized the chemical properties and molecular compositions of WSOA at a rural site in North China Plain during winter using a high-resolution aerosol mass spectrometer and electrospray ionization high-resolution orbitrap mass spectrometer(ESI-HRMS).Our results show that the mass concentration of WSOA was significantly higher than that observed in Beijing in winter 2020,contributing about 56%of OA on average.CHO compounds(56%-74%)and CHN compounds(66%-80%)dominated in negative mode and positive mode,respectively,while CHON accounted for 15%-41%across both modes.The chemical characteristics of WSOA varied with polluted levels and between day and night.As pollution intensified,the abundance of CHO-compounds with condensed aromatics increased by 9%and the number of highly oxygenated molecules(HOMs)molecular formula detected in server haze was more than double that of clean days.CHO-compounds with ten carbon atoms(C_(10))were more abundant at night while those with nine carbon atoms(C_(9))were higher during the day.High levels of CHN+compounds were linked to nighttime biomass burning,whereas CHON compounds were more abundant during the day.Increased pollution also led to the formation of more complex CHON-compounds,indicating that organonitrates continue to play a significant role in rural pollution.
基金supported by the National Key R&D Program of China(Nos.2022YFC3701000 and 2021YFA1601800)the National Natural Science Foundation of China(Nos.42230701 and 42375105)+1 种基金the Foundation for Program of Science and Technology Research(No.2024A1515011937)Guangdong Foundation for Program of Science and Technology Research(No.2023B1212060049).
文摘Particulate levoglucosan is an important tracer for biomass burning emission in ambient air.However,recent studies question its reliability as a biomass burning tracer in Chinesemega cities due to important contribution from potential non-biomass burning sources,such as cooking.To address this,we examined the dynamic variation and sources of levoglucosan using a chemical ionization mass spectrometer and other advanced instruments during Beijing’s summer of 2021.The average mass concentration of levoglucosan and its isomer(C_(6)H_(10)O_(5))was 0.025±0.014μg/m^(3),constituting 0.55%±0.32%of total organic carbon(OC)in this campaign.Despite cooking emissions contributing significantly to the organic aerosol(OA,20%),levoglucosan and its isomers correlated more strongly with biomass-burning related tracers(R>0.6),black carbon(R=0.72)and less so with cooking-related sources(R=0.3).This indicates that levoglucosan is primarily dominated by biomass-burning emissions rather than cooking in Beijing’s urban areas during summertime.The diurnal variation of levoglucosan concentrations highlighted the importance of daytime and nocturnal biomass burning emissions during polluted periods in Beijing.Using levoglucosan as a tracer to quantify the biomass burning OC(BBOC),we found good agreement on the time series of BBOC between the tracermethod and other independent source apportionmentmethod.This reaffirms the reliability of levoglucosan as a biomass burning tracer.Biomass burning contributed an average of 7%-8%to OC,highlighting its significant impact on Beijing’s summer air quality.Our study enhances understanding of biomass burning influences on ambient aerosol in typical urban areas.
基金financially supported by Council of Scientific and Industrial Research(CSIR)(grant no.09/045(1399)/2015-EMR-I)the Ministry of Earth Sciences(Mo ES),Government of India(grant no.Mo ES/P.O.(Geo)/95/2017)。
文摘Soil erosion is one of the major global hazards threatening the food security of the world population.Soil erosion can be a result of both natural and anthropogenic processes.Field monitoring and models(numerical and physical)are commonly used to quantify soil erosion.However,field methods are time-consuming and the models inherently work with a level of uncertainty.Soil erosion studies in the Himalayas have been mostly carried out using modelling but there is a lack of sufficient field data to validate the results.We quantified soil erosion in a small catchment(Pranmati)in the Himalayas using the fallout meteoric^(10)Be nuclide for the first time.Based on the^(10)Be flux delivery rates determined from global circulation models(GCM),we calculated the rates of soil erosion at discrete points in the hilltop and mid-slope regions of hillslopes.The erosion rates vary between 17 mm kyr^(-1)to 68 mm kyr^(-1).These rates were determined in pristine areas that are unaffected by anthropogenic activities,thus,indicate the background erosion rates in the region.We established empirical relationships with estimated erosion rates and topographic parameters to assess the sediment dynamics in the hillslopes.It was observed that the sediment redistribution process operates differently in the mid-slope region compared to the hilltop region,due to increasing complexity of the active processes in the mid-slope region.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA25051000,XDA25010100,XDA25010300,XDA25030100,and XDA25030200)。
文摘Warm dense plasmas are crucial for high-energy-density physics and inertial confinement fusion research.Experiments involving laser-irradiated copper(Cu)foil were performed at the Shenguang-II facility.A highly oriented pyrolytic graphite crystal spectrometer measured the time-integrated spectral distribution of Cu under varying laser intensities.Using the two-dimensional radiation-hydrodynamics code FLASH and the spectral analysis code FLYCHK,we simulated the temporal evolution of plasma density and temperature distributions,as well as the emission intensities of spectral lines at different temperatures and densities.The simulation results revealed that the two-electron satellite lines(J)and the resonance line(W)emissions of Cu originate predominantly from the radiation region near the critical density surface,with a density range from approximately 0.5 nc to 1.0 nc,and radiate primarily during the laser irradiation period.By analyzing the J/W intensity ratio of the measured spectral lines,we estimated the electron temperatures near the critical-density surface under different laser intensities.
