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
A theoretical study on the red-shift of laser-induced electro-absorption is presented. It is found that laser-induced red-shift scales with the cube root of the pump laser intensity in the optical tunneling regime and...A theoretical study on the red-shift of laser-induced electro-absorption is presented. It is found that laser-induced red-shift scales with the cube root of the pump laser intensity in the optical tunneling regime and has an obvious deviation from this scale in the multi-photon regime. Our results show that in the optical tunneling regime, the laser-induced red shift has the same law as that in the direct current （DC） approximation. Though the scales are the same in the optical tunneling regime, the physical pictures in the two cases are quite different. The electro-absorption in the DC case is a tunneling-assisted transition process, while the laser-induced electro-absorption is a mixed multi-photon process.展开更多
A theoretical study for femtosecond laser-induced ultrafast electro-absorption of bulk solids is presented.Our numerical results show that,in the case of low intensity of the pump laser where the interaction between t...A theoretical study for femtosecond laser-induced ultrafast electro-absorption of bulk solids is presented.Our numerical results show that,in the case of low intensity of the pump laser where the interaction between the pump laser and solids is in the multi-photon regime,the energy band of solids can be approximately taken as a parabolic band and electro-absorption spectrums from the parabolic band and real band are nearly the same.While,in the case of high intensity where the interaction is in the tunneling regime,spectrums from the parabolic band and real band are quite different.The physical mechanism for the difference in the tunneling regime is found.We find that the non-parabolic parts of the real energy band and Bragger scattering of electrons near the first Brillouin zone boundaries,which are neglected in previous studies,strongly influence the electro-absorption spectrum in the tunneling regime.These two physical processes cause the difference of spectrums.Our theoretical results are in accordance with the experiment result.展开更多
Herein,two antimony sulfates,named RbSb(SO_(4))_(2)(1)and CsSb(SO_(4))_(2)(2),have been successfully synthesized with the introduction of Sb^(3+)cation with stereochemically active lone pairs(SCALP)into sulfates by th...Herein,two antimony sulfates,named RbSb(SO_(4))_(2)(1)and CsSb(SO_(4))_(2)(2),have been successfully synthesized with the introduction of Sb^(3+)cation with stereochemically active lone pairs(SCALP)into sulfates by the conventional hydrothermal method.Both two compounds endow short ultraviolet(UV)absorption edges(281 nm and 278 nm,respectively)and large birefringence(0.171@546 nm and 0.174@546 nm,respectively),which means that they are promising short-wave UV optical materials.Interestingly,though both of the two compounds exhibit similar 1D chained structures,and possess the same functional moieties including SbO4 seesaws and SO4 tetrahedral groups,they exhibit significantly opposite macroscopic symmetries,i.e.,compound 1 crystallizes in a centrosymmetric(CS)manner(P2_(1)/n)and compound 2 in a noncentrosymmetric(NCS)manner(P2_(1)2_(1)2_(1)),due to the size of cations[r(Rb+)=1.56 A˚,r(Cs+)=1.67 A˚]affects the orientation of SCALP of the adjacent Sb^(3+).展开更多
Quasiparticle band structures of the defective anatase TiO2 bulk with O vacancy, Ti interstitial and H interstitial are investigated by the GW method within many-body Green＇s function theory. The computed direct band...Quasiparticle band structures of the defective anatase TiO2 bulk with O vacancy, Ti interstitial and H interstitial are investigated by the GW method within many-body Green＇s function theory. The computed direct band gap of the perfect anatase bulk is 4.3 eV, far larger than the experimental optical absorption edge （3.2 eV）. We found that this can be ascribed to the inherent defects in anatase which drag the conduction band （CB） edge down. The occupied band-gap states induced by these defects locate close to the CB edge, exclud- ing the possible contribution of these bulk defects to the deep band-gap state below CB as observed in experiments.展开更多
The chemical and physical properties of rhenium render it a highly demanded metal for advanced applications in important industrial fields. This very scarce element occurs mainly in ores of porphyry copper-molybdenum ...The chemical and physical properties of rhenium render it a highly demanded metal for advanced applications in important industrial fields. This very scarce element occurs mainly in ores of porphyry copper-molybdenum deposits associated with the mineral molybdenite, MoS2, but it has also been found in granite pegmatites and quartz veins as well as in volcanic gases. Molybdenite is a typical polytype mineral which crystal structure is based on the stacking of [S-Mo-S] with molybdenum in prismatic coordination by sulphide anions;however, it is not yet clearly established if rhenium ions replace Mo4+ cations in a disordered way or else, if such replacement gives rise to dispersed nanodomains of a rhenium-rich phase. As a contribution to clarify this question, an X-ray absorption spectroscopy (XANES) study using synchrotron radiation was performed at the Re L3-edge of rhenium-containing molybdenite samples. Obtained results are described and discussed supporting the generally accepted structural perspective that rhenium is mainly carried by molybdenite through the isomorphous replacement of Mo, rather than by the formation of dispersed Re-specific nanophase(s).展开更多
Finding suitable strategies to effectively enhance the optical properties of materials are the goal being pursued by researchers.Herein,cation-anion synergetic interactions strategy was proposed to develop two novel o...Finding suitable strategies to effectively enhance the optical properties of materials are the goal being pursued by researchers.Herein,cation-anion synergetic interactions strategy was proposed to develop two novel organic-inorganic hybrid antimony-based optical materials,(C_(3)H_(5)N_(2))Sb F_(2)SO_(4)(I)and(C_(5)H_(6)N)Sb F_(2)SO_(4)(Ⅱ),which were obtained by introducing Sb^(3+)cation containing stereochemically active lone-pair(SCALP)and organicπ-conjugated cations into sulphate system.The synergistic interactions of the organicπ-conjugated cations,the inorganic[SbO_(2)F_(2)]^(3-)seesaw anions and the[SO_(4)]^(2-)distorted tetrahedra anions make their ultraviolet(UV)absorption edges approach 297 and 283 nm,respectively,and raise their birefringence up to 0.193@546 nm and 0.179@546 nm,respectively.Interestingly,although the two compounds have the same stoichiometric ratio and similar one-dimensional(1D)chain structure,they show opposite macroscopic symmetry,where the NCS compound(Ⅱ)exhibits a large secondharmonic generation(SHG)response(1.6 times that of KH_(2)PO_(4)).The two reported compounds are found to be promising UV optical materials in the experimental tests.展开更多
Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus （S. metallicus） at 65 ℃ was investigated by X-ray diffraction （XRD）, diffuse re...Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus （S. metallicus） at 65 ℃ was investigated by X-ray diffraction （XRD）, diffuse reflectance Fourier transform infrared spectroscopy （FT-IR） and sulfur K-edge X-ray absorption near edge structure spectroscopy （XANES）. The results show that the presence of S. metallicus effectively enhances the dissolution of the mineral. The yield of zinc increases from 0.5 g/L in sterile control to 2.7 g/L in bioleaching. The pyrite in the concentrate facilitates zinc dissolution in the early stage, but has hindrance role in the late stage for the formation of jarosite. Sulfur speciation analyses show that jarosite and elemental sulfur are main products in bioleaching process, and the accumulation ofjarosite is mainly responsible for the decline of leaching efficiency.展开更多
Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorp...Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves （CTLs）,which were sampled from 5 local fields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their corresponding compounds were ＋6 （sulfate,include inorganic sulfate and organic sulfate）,＋5.2 （sulfonate）,＋2.2 （suloxides）,＋0.6 （thiols and thiothers）,＋0.2 （organic sulfides）.Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds （organic sulfides,thiols,thioethers,sulfoxide and sulfonate） assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.展开更多
The multiple scattering cluster (MSC) method has been employed to perform a theoretical analysis on carbon is near edge X-ray absorption fine structure of the deuteron acetylene (C2 D2) adsorbed on Si(111)7× 7 at...The multiple scattering cluster (MSC) method has been employed to perform a theoretical analysis on carbon is near edge X-ray absorption fine structure of the deuteron acetylene (C2 D2) adsorbed on Si(111)7× 7 at room temperature. From the MSC study. it is confirmed that the (22D2 molecule is bonded to a pair of adjacent Si adatom and Si restatom with C-Si bond length about 0.18nm. The carbon-deuteron bond is bent away front the surface and the CCD bond angle is about 120°. The molecule plane tilt slightly away from the surface normal. Compared with C2D2 in gas phase, the C-C bond and C-D bond are elongated by about 0.03nm and 0.02nm respectively when acetylene was adsorbed on the subtrate. Keyowrds: adsorption of deuteron acetylene on Si(111)7×7. near edge X- ray absorption fine structure. multiple scattering cluster method展开更多
The second harmonic generation(SHG)response,birefringence,and ultraviolet(UV)absorption edge are three crucial parameters of UV nonlinear optical(NLO)crystals.However,striking a balance among these parameters has been...The second harmonic generation(SHG)response,birefringence,and ultraviolet(UV)absorption edge are three crucial parameters of UV nonlinear optical(NLO)crystals.However,striking a balance among these parameters has been a challenging endeavor.The synergistic combination of mixed chromophores is regarded as an effective strategy to achieve this task,leveraging the benefits of both functional motifs.Herein,a novel UV NLO crystal,Rb(NO_(3))(SO_(3)NH_(3)),was successfully designed by integrating the π-conjugated[NO_(3)]unit with the non-π-conjugated[SO_(3)NH_(3)]unit.As anticipated,the π-conjugated[NO_(3)]units contribute to a robust SHG effect and birefringence,while the non-π-conjugated[SO_(3)NH_(3)]units help in widening the band gap and controlling the birefringence within an optimal range by decoupling theπ-conjugated interactions and reducing the system’s anisotropy.Consequently,it exhibits a strong SHG response(7×KDP),moderate birefringence(0.07@546 nm),and a short UV absorption edge(208 nm),marking it as a promising UV NLO crystal.展开更多
The structural evolution and optical properties of CL-20/DNB cocrystals under high pressure are systematically studied via Raman,florescence,and absorption spectroscopy and Gaussian calculations.Interestingly,the pres...The structural evolution and optical properties of CL-20/DNB cocrystals under high pressure are systematically studied via Raman,florescence,and absorption spectroscopy and Gaussian calculations.Interestingly,the pressure induced a significant change in color from colorless to yellow to red in the CL-20/DNB cocrystal sample.This phenomenon is accompanied by a redshift in the absorption edge,resulting from the enhanced hydrogen bonding interaction and theπ‒πstacking effect.Additionally,the photoluminescence(PL)emission clearly increases between 1 atm and 19.5 GPa and quenches later above 20 GPa,which is also caused by the change in the lattice stacking of the cocrystal explosive under high pressure.Moreover,no structural phase transition occurs in the CL-20/DNB cocrystal at pressures ranging from 1 atm to 20 GPa according to the high-pressure Raman spectra,indicating that the cocrystal demonstrates markedly superior structural stability compared with either CL-20 or DNB when considered individual components under high pressure.展开更多
Lithium-rich layered oxide cathodes have an advantage of high energy density.However,continuous capacity fading and voltage hysteresis have largely restricted their practical application.In this work,we investigated i...Lithium-rich layered oxide cathodes have an advantage of high energy density.However,continuous capacity fading and voltage hysteresis have largely restricted their practical application.In this work,we investigated in depth the voltage-fading mechanism of Li-rich materials by in situ Raman spectroscopy,X-ray absorption near edge structure(XANES)spectroscopy,andhigh-resolution transmission electron microscopy(HRTEM).展开更多
Ce^(3+)-doped gadolinium-based borosilicate(GBSC_(x))glass scintillators with an ultra-high concentration of 16%(mole fraction)were synthesized in ambient atmosphere for future calorimeter application.The valence stat...Ce^(3+)-doped gadolinium-based borosilicate(GBSC_(x))glass scintillators with an ultra-high concentration of 16%(mole fraction)were synthesized in ambient atmosphere for future calorimeter application.The valence state of Ce was precisely controlled in the glass by the X-ray absorption near edge structure(XANES)spectrum.With the increased Ce^(3+)concentration,the bridging oxygen(BO)/non-bridging oxygen(NBO)ratio decreases notably from 5.15 to 0.56.The GBSC_(x)glass scintillators exhibit the broad photoluminescence(PL)band within 350-550 nm regions,with a maximum PL quantum yield(PL QY)of 60.6%.In X-ray excited luminescence(XEL),the integral intensity of the GBSC2 glass is 18.4%compared to the BGO crystal.Meanwhile,it has the highest light yield of 1043 photons/MeV with an energy resolution of 28.4%at 662 keV underγ-ray excitation.When the doped concentration of Ce^(3+)exceeds 4%(mole fraction),the proportion of light yield within 1μs integral gate exceeds 95%,which conforms to the requirement of fast time response.Interestingly,the concentration quenching effect of high concentration Ce^(3+)(x≤14)does not occur in the glass scintillators underγ-ray excitation.With the increase of Ce^(3+)concentration,both the fast(100-18 ns)and slow(1000-59 ns)components of scintillation decay time decrease dramatically.Therefore,the developed GBSC_(x)glass scintillators,featured with the reasonable light yield and fast time response,have a promising application in future high energy physics(HEP)experiments.展开更多
X-ray absorption near edge structure(XANES)spectroscopy is a powerful technique for characterizing the chemical state andsymmetry of individual elements within materials,but requires collecting data at many energy poi...X-ray absorption near edge structure(XANES)spectroscopy is a powerful technique for characterizing the chemical state andsymmetry of individual elements within materials,but requires collecting data at many energy points which can be time-consuming.While adaptive sampling methods exist for efficiently collecting spectroscopic data,they often lack domain-specific knowledge about the structure of XANES spectra.Here we demonstrate a knowledge-injected Bayesian optimization approach for adaptive XANES data collection that incorporates understanding of spectral features like absorption edges and pre-edge peaks.We show this method accurately reconstructs the absorption edge of XANES spectra using only 15–20%of the measurement points typically needed for conventional sampling,while maintaining the ability to determine the x-ray energy of the sharp peak after the absorption edge with errors less than 0.03 eV,the absorption edge with errors less than 0.1 eV;and overall root-mean-square errors less than 0.005 compared to traditionally sampled spectra.Our experiments on battery materials and catalysts demonstrate the method’s effectiveness for both static and dynamic XANES measurements,improving data collection efficiency and enabling better time resolution for tracking chemical changes.This approach advances the degree of automation in XANES experiments,reducing the common errors of under-or over-sampling points near the absorption edge and enabling dynamic experiments that require high temporal resolution or limited measurement time.展开更多
Organic-inorganic hybrid perovskite materials have been receiving considerable attention due to their promising applications in many optoelectronic fields. However, the optical bandgap of CH3NH3PbI3 perovskite is stil...Organic-inorganic hybrid perovskite materials have been receiving considerable attention due to their promising applications in many optoelectronic fields. However, the optical bandgap of CH3NH3PbI3 perovskite is still disputed. In order to comprehend the intrinsic characteristics of these materials, we study the near-band-edge optical responses of the solution-processed CH3NH3PbI3 perovskite crystals by photoconductivity and reflectance spectroscopy at room temperature. All these spectra of the CH3NH3PbI3 polycrystals show only one significant absorption edge at 1.58 eV. However, we observe an extra absorption edge at 1.47 eV in CH3NH3PbI3 single crystal. We establish a simple kinetic model of charge annihilation processes to explain why the low-energy structure of the photoconductivity and diffuse reflectance spectra of CH3NH3PbI3 polyerystals disappear, which provides another possibility for understanding the difference in absorption edge. It is noteworthy that this low-energy absorption edge of CH3NH3PbI3 single crystal has, to the best of our knowledge, seldom been reported on organic-inorganic hybrid perovskites. Therefore, the CH3NH3PbI3 single crystal exhibits a relatively wide absorption which makes it a promising candidate for photoelectric applications.展开更多
Semiconductor(Zn\-\%x\%Cd 1-x S) doped silica glasses were prepared by Sol_Gel process and \%in situ\% growth technique. The structure of the materials was characterized by X_ray diffraction technique, the particle si...Semiconductor(Zn\-\%x\%Cd 1-x S) doped silica glasses were prepared by Sol_Gel process and \%in situ\% growth technique. The structure of the materials was characterized by X_ray diffraction technique, the particle size of semiconductor crystallites from X_ray patterns was estimated less than 10 nm. From absorption spectra, it is obtained that the absorption edges shifted to short wavelength diraction when Zn contents increased, and the absorption edge can be adjusted from 2.46 eV to 2.96 eV by controlling Zn contents. The third_order nonlinear optical susceptibility was studied at 532 nm with 8 ns pulse laser by degenerate four wave mixing (DFWM) technique.展开更多
Highly efficient and durable water oxidation electrocatalysts are critically important in a wide range of clean energy technologies,including water electrolyzers and rechargeable metal-air batteries.Here,we report a n...Highly efficient and durable water oxidation electrocatalysts are critically important in a wide range of clean energy technologies,including water electrolyzers and rechargeable metal-air batteries.Here,we report a novel sonochemical approach to synthesize amorphous nickel-iron oxides/carbon nanohybrids with tunable compositions for the oxygen evolution reaction （OER）.The sonochemically synthesized amorphous electrocatalysts with optimal composition exhibit a low overpotential of 290 mV at 10 mA＆#183;cm-2 and a Tafel slope of 31 mV＆#183;decade-1 in a 0.1 M KOH electrolyte,outperforming the benchmark RuO2 catalyst.Meanwhile,these nanohybrids are also highly stable and remain amorphous even after prolonged cycling.In addition to amorphism,sonochemistry endows as-prepared nickel-iron oxides/carbon nanohybrids with a simultaneously formed carbon scaffold and internal Ni（0）,which can enhance the stability and activity for the OER.This work demonstrates that sonochemistry is a unique method for synthesizing amorphous metal oxides toward an efficient and durable OER.展开更多
The total electron yield （TEY） mode has been developed successfully for XANES measurements at Beamline 4BTA of BSRF （Beijing Synchrotron Radiation Facility）. Its performance was studied by measuring sulphur K-edge...The total electron yield （TEY） mode has been developed successfully for XANES measurements at Beamline 4BTA of BSRF （Beijing Synchrotron Radiation Facility）. Its performance was studied by measuring sulphur K-edge XANES of three CdS samples （mixed with graphite powder as an electric conductor） with different concentration： 75%, 50~ and 25%. The data are collected in TEY mode and fluorescence yield （FY） mode respectively for comparison. The results demonstrate that the TEY spectra of three samples agree well with each other after the background is subtracted and normalized. The measured XANES spectra by TEY mode without bias and with 100V bias are almost identical to one another, but the signal-to-noise ratio of spectra measured without bias is better than that with 100V bias. The consistency of the self-absorption corrected FY spectra and TEY spectra are within 10% for the three samples.展开更多
Thin silicon phthalocyanine dichloride films on HOPG were prepared and the sample was heated in the vacuum with laser. The thickness of the thin sample on HOPG was checked by X-ray photoemission spectroscopy. The orie...Thin silicon phthalocyanine dichloride films on HOPG were prepared and the sample was heated in the vacuum with laser. The thickness of the thin sample on HOPG was checked by X-ray photoemission spectroscopy. The orientation of the molecules in respect to the substrate plane was investigated by measuring the silicon K-edge near edge X-ray absorption fine structure （NEXAFS）. In the NEXAFS spectra of the thin sample, two clear peaks which were assigned to Is → σ^＊Si-N and 1s→ σ^＊Si-Cl appeared around 1847.2 eV and 1843.1 eV respectively. The intensities of the resonance peaks showed strong polarization dependence. A quantitative analysis of the polarization dependence revealed that the Si-N bond tended to lie down while the Si-Cl bond was out of the molecular plane.展开更多
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Project supported by the Fundamental Research Funds for the Central Universities,China (Grant No.A735496)the National Natural Science Foundation of China (Grant No.61178018)the Ph.D. Funding Support Program of the Education Ministry of China (Grant No.20110185110007)
文摘A theoretical study on the red-shift of laser-induced electro-absorption is presented. It is found that laser-induced red-shift scales with the cube root of the pump laser intensity in the optical tunneling regime and has an obvious deviation from this scale in the multi-photon regime. Our results show that in the optical tunneling regime, the laser-induced red shift has the same law as that in the direct current （DC） approximation. Though the scales are the same in the optical tunneling regime, the physical pictures in the two cases are quite different. The electro-absorption in the DC case is a tunneling-assisted transition process, while the laser-induced electro-absorption is a mixed multi-photon process.
基金Project supported by the National Natural Science Foundation of China(Grant No.61505023)
文摘A theoretical study for femtosecond laser-induced ultrafast electro-absorption of bulk solids is presented.Our numerical results show that,in the case of low intensity of the pump laser where the interaction between the pump laser and solids is in the multi-photon regime,the energy band of solids can be approximately taken as a parabolic band and electro-absorption spectrums from the parabolic band and real band are nearly the same.While,in the case of high intensity where the interaction is in the tunneling regime,spectrums from the parabolic band and real band are quite different.The physical mechanism for the difference in the tunneling regime is found.We find that the non-parabolic parts of the real energy band and Bragger scattering of electrons near the first Brillouin zone boundaries,which are neglected in previous studies,strongly influence the electro-absorption spectrum in the tunneling regime.These two physical processes cause the difference of spectrums.Our theoretical results are in accordance with the experiment result.
基金the National Natural Science Foundation of China(Nos.22122106,22071158,21971171)the Fundamental Research Funds from Sichuan University(No.2021SCUNL101).
文摘Herein,two antimony sulfates,named RbSb(SO_(4))_(2)(1)and CsSb(SO_(4))_(2)(2),have been successfully synthesized with the introduction of Sb^(3+)cation with stereochemically active lone pairs(SCALP)into sulfates by the conventional hydrothermal method.Both two compounds endow short ultraviolet(UV)absorption edges(281 nm and 278 nm,respectively)and large birefringence(0.171@546 nm and 0.174@546 nm,respectively),which means that they are promising short-wave UV optical materials.Interestingly,though both of the two compounds exhibit similar 1D chained structures,and possess the same functional moieties including SbO4 seesaws and SO4 tetrahedral groups,they exhibit significantly opposite macroscopic symmetries,i.e.,compound 1 crystallizes in a centrosymmetric(CS)manner(P2_(1)/n)and compound 2 in a noncentrosymmetric(NCS)manner(P2_(1)2_(1)2_(1)),due to the size of cations[r(Rb+)=1.56 A˚,r(Cs+)=1.67 A˚]affects the orientation of SCALP of the adjacent Sb^(3+).
文摘Quasiparticle band structures of the defective anatase TiO2 bulk with O vacancy, Ti interstitial and H interstitial are investigated by the GW method within many-body Green＇s function theory. The computed direct band gap of the perfect anatase bulk is 4.3 eV, far larger than the experimental optical absorption edge （3.2 eV）. We found that this can be ascribed to the inherent defects in anatase which drag the conduction band （CB） edge down. The occupied band-gap states induced by these defects locate close to the CB edge, exclud- ing the possible contribution of these bulk defects to the deep band-gap state below CB as observed in experiments.
基金Work developed within the project MinReMol(Ref.EXPL/AAG-REC/0978/2012,COMPETE:FCOMP-01-0124-FEDER-027516)financed by FEDER Funds through“Programa Operacional Factores de Competitividade(COMPETE)” by National Funds through FCT(Fun-dação para a Ciência e a Tecnologia)+2 种基金Thanks are due to Mr.Paul Carter of Ivanhoe Australia for the gracious supply of sample MDQ0191EU financial support to per-form the X-ray absorption experiments at the ESRF is acknowledgedAuthors affiliated to CENI-MAT/I3N ac-knowledge the support of the Strategic Project-LA25-2011-2012(ref.PEst-C/CTM/LA0025/2011).
文摘The chemical and physical properties of rhenium render it a highly demanded metal for advanced applications in important industrial fields. This very scarce element occurs mainly in ores of porphyry copper-molybdenum deposits associated with the mineral molybdenite, MoS2, but it has also been found in granite pegmatites and quartz veins as well as in volcanic gases. Molybdenite is a typical polytype mineral which crystal structure is based on the stacking of [S-Mo-S] with molybdenum in prismatic coordination by sulphide anions;however, it is not yet clearly established if rhenium ions replace Mo4+ cations in a disordered way or else, if such replacement gives rise to dispersed nanodomains of a rhenium-rich phase. As a contribution to clarify this question, an X-ray absorption spectroscopy (XANES) study using synchrotron radiation was performed at the Re L3-edge of rhenium-containing molybdenite samples. Obtained results are described and discussed supporting the generally accepted structural perspective that rhenium is mainly carried by molybdenite through the isomorphous replacement of Mo, rather than by the formation of dispersed Re-specific nanophase(s).
基金supported by the National Natural Science Foundation of China(Nos.22122106,22071158,21971171,22305166)the Fundamental Research Funds from Sichuan University(No.2021SCUNL101)the Natural Science Foundation of Sichuan Province(No.2023NSFC1066)。
文摘Finding suitable strategies to effectively enhance the optical properties of materials are the goal being pursued by researchers.Herein,cation-anion synergetic interactions strategy was proposed to develop two novel organic-inorganic hybrid antimony-based optical materials,(C_(3)H_(5)N_(2))Sb F_(2)SO_(4)(I)and(C_(5)H_(6)N)Sb F_(2)SO_(4)(Ⅱ),which were obtained by introducing Sb^(3+)cation containing stereochemically active lone-pair(SCALP)and organicπ-conjugated cations into sulphate system.The synergistic interactions of the organicπ-conjugated cations,the inorganic[SbO_(2)F_(2)]^(3-)seesaw anions and the[SO_(4)]^(2-)distorted tetrahedra anions make their ultraviolet(UV)absorption edges approach 297 and 283 nm,respectively,and raise their birefringence up to 0.193@546 nm and 0.179@546 nm,respectively.Interestingly,although the two compounds have the same stoichiometric ratio and similar one-dimensional(1D)chain structure,they show opposite macroscopic symmetry,where the NCS compound(Ⅱ)exhibits a large secondharmonic generation(SHG)response(1.6 times that of KH_(2)PO_(4)).The two reported compounds are found to be promising UV optical materials in the experimental tests.
基金Project(50974140) supported by the National Natural Science Foundation of ChinaProject(VR-09157) supported by Beijing Synchrotron Radiation Facility (BSRF) Public User Program,China
文摘Sulfur speciation transformation during bioleaching of pyrite-containing sphalerite concentrate by thermophile Sulfolobus metallicus （S. metallicus） at 65 ℃ was investigated by X-ray diffraction （XRD）, diffuse reflectance Fourier transform infrared spectroscopy （FT-IR） and sulfur K-edge X-ray absorption near edge structure spectroscopy （XANES）. The results show that the presence of S. metallicus effectively enhances the dissolution of the mineral. The yield of zinc increases from 0.5 g/L in sterile control to 2.7 g/L in bioleaching. The pyrite in the concentrate facilitates zinc dissolution in the early stage, but has hindrance role in the late stage for the formation of jarosite. Sulfur speciation analyses show that jarosite and elemental sulfur are main products in bioleaching process, and the accumulation ofjarosite is mainly responsible for the decline of leaching efficiency.
基金supported by the National Natural Science Foundation of China(No.11079049,11005141,10775150)the Major Project of Knowledge Innovation Program of Chinese Academy of Sciences(No.KJCX3.SYW.N3)
文摘Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology.A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves （CTLs）,which were sampled from 5 local fields in Shanghai,China.Annual SO2 concentration,SO42-concentration in atmospheric particulate,SO42-and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs.Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg.The mainly detected sulfur states and their corresponding compounds were ＋6 （sulfate,include inorganic sulfate and organic sulfate）,＋5.2 （sulfonate）,＋2.2 （suloxides）,＋0.6 （thiols and thiothers）,＋0.2 （organic sulfides）.Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977,which suggested that sulfur accumulated in CTLs as sulfate form.Reduced sulfur compounds （organic sulfides,thiols,thioethers,sulfoxide and sulfonate） assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg.The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination.From urban to suburb place,sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced,but a dramatic increase presented near the seashore,where the marine sulfate emission and maritime activity pollution were significant.The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.
基金The authors acknowledge the financial support of the National Natural Science Foun-dation of China (Grant No.19974036)
文摘The multiple scattering cluster (MSC) method has been employed to perform a theoretical analysis on carbon is near edge X-ray absorption fine structure of the deuteron acetylene (C2 D2) adsorbed on Si(111)7× 7 at room temperature. From the MSC study. it is confirmed that the (22D2 molecule is bonded to a pair of adjacent Si adatom and Si restatom with C-Si bond length about 0.18nm. The carbon-deuteron bond is bent away front the surface and the CCD bond angle is about 120°. The molecule plane tilt slightly away from the surface normal. Compared with C2D2 in gas phase, the C-C bond and C-D bond are elongated by about 0.03nm and 0.02nm respectively when acetylene was adsorbed on the subtrate. Keyowrds: adsorption of deuteron acetylene on Si(111)7×7. near edge X- ray absorption fine structure. multiple scattering cluster method
基金supported by the National Natural Science Foundation of China(22305038,22222510)the Natural Science Foundation of Fujian Province(2021J011080).
文摘The second harmonic generation(SHG)response,birefringence,and ultraviolet(UV)absorption edge are three crucial parameters of UV nonlinear optical(NLO)crystals.However,striking a balance among these parameters has been a challenging endeavor.The synergistic combination of mixed chromophores is regarded as an effective strategy to achieve this task,leveraging the benefits of both functional motifs.Herein,a novel UV NLO crystal,Rb(NO_(3))(SO_(3)NH_(3)),was successfully designed by integrating the π-conjugated[NO_(3)]unit with the non-π-conjugated[SO_(3)NH_(3)]unit.As anticipated,the π-conjugated[NO_(3)]units contribute to a robust SHG effect and birefringence,while the non-π-conjugated[SO_(3)NH_(3)]units help in widening the band gap and controlling the birefringence within an optimal range by decoupling theπ-conjugated interactions and reducing the system’s anisotropy.Consequently,it exhibits a strong SHG response(7×KDP),moderate birefringence(0.07@546 nm),and a short UV absorption edge(208 nm),marking it as a promising UV NLO crystal.
基金supported by the Fundamental Research Funds for the Central Universities(WK2030000058)the Fund of the National Key Laboratory of Shock Wave and Detonation Physics(JCKYS2022212008)acknowledge beamline 15U1 of the Shanghai Synchrotron Radiation Facility(SSRF)and Supercomputing Center of the University of Science and Technology of China.
文摘The structural evolution and optical properties of CL-20/DNB cocrystals under high pressure are systematically studied via Raman,florescence,and absorption spectroscopy and Gaussian calculations.Interestingly,the pressure induced a significant change in color from colorless to yellow to red in the CL-20/DNB cocrystal sample.This phenomenon is accompanied by a redshift in the absorption edge,resulting from the enhanced hydrogen bonding interaction and theπ‒πstacking effect.Additionally,the photoluminescence(PL)emission clearly increases between 1 atm and 19.5 GPa and quenches later above 20 GPa,which is also caused by the change in the lattice stacking of the cocrystal explosive under high pressure.Moreover,no structural phase transition occurs in the CL-20/DNB cocrystal at pressures ranging from 1 atm to 20 GPa according to the high-pressure Raman spectra,indicating that the cocrystal demonstrates markedly superior structural stability compared with either CL-20 or DNB when considered individual components under high pressure.
基金financially supported by the Basic Research Project of the Science and Technology Innovation Commission of Shenzhen(no.JCYJ20170412153139454)the National Natural Science Foundation of China(no.21875097)+1 种基金Natural Science Foundation of Guangdong Province(no.2018A030313725 and 2018B030322001)the Professorial and Doctoral Scientific Research Foundation of Huizhou University(no.2020JB025).
文摘Lithium-rich layered oxide cathodes have an advantage of high energy density.However,continuous capacity fading and voltage hysteresis have largely restricted their practical application.In this work,we investigated in depth the voltage-fading mechanism of Li-rich materials by in situ Raman spectroscopy,X-ray absorption near edge structure(XANES)spectroscopy,andhigh-resolution transmission electron microscopy(HRTEM).
基金supported by the National Natural Science Foundation of China(Nos.52472001,12335012,and 12375183)the opening fund of the Key Laboratory of Rare Earths,Chinese Academy of Sciences,and the Science and Technology Plan Project of Ji’an City(No.20233-117685)+1 种基金the College Student Innovation and Entrepreneurship Training Program of China(No.202510419009)Jiangxi Province(No.S202510419012)。
文摘Ce^(3+)-doped gadolinium-based borosilicate(GBSC_(x))glass scintillators with an ultra-high concentration of 16%(mole fraction)were synthesized in ambient atmosphere for future calorimeter application.The valence state of Ce was precisely controlled in the glass by the X-ray absorption near edge structure(XANES)spectrum.With the increased Ce^(3+)concentration,the bridging oxygen(BO)/non-bridging oxygen(NBO)ratio decreases notably from 5.15 to 0.56.The GBSC_(x)glass scintillators exhibit the broad photoluminescence(PL)band within 350-550 nm regions,with a maximum PL quantum yield(PL QY)of 60.6%.In X-ray excited luminescence(XEL),the integral intensity of the GBSC2 glass is 18.4%compared to the BGO crystal.Meanwhile,it has the highest light yield of 1043 photons/MeV with an energy resolution of 28.4%at 662 keV underγ-ray excitation.When the doped concentration of Ce^(3+)exceeds 4%(mole fraction),the proportion of light yield within 1μs integral gate exceeds 95%,which conforms to the requirement of fast time response.Interestingly,the concentration quenching effect of high concentration Ce^(3+)(x≤14)does not occur in the glass scintillators underγ-ray excitation.With the increase of Ce^(3+)concentration,both the fast(100-18 ns)and slow(1000-59 ns)components of scintillation decay time decrease dramatically.Therefore,the developed GBSC_(x)glass scintillators,featured with the reasonable light yield and fast time response,have a promising application in future high energy physics(HEP)experiments.
基金supported by the U.S. DOE Office of Science-Basic Energy Sciences, under Contract No. DE-AC02-06CH11357The research was also supported by the Canadian Light Source and its funding partners. Data for demonstrations were collected at beamlines 25-ID, 20-BM, and 10-ID (MRCAT) of the Advanced Photon Source+1 种基金The NMC-111 electrodes were supplied by the U.S. Department of Energy’s (DOE) CAMP (Cell Analysis, Modeling and Prototyping) Facility, Argonne National LaboratoryThe CAMP Facility is fully supported by the DOE Vehicle Technologies Office (VTO).
文摘X-ray absorption near edge structure(XANES)spectroscopy is a powerful technique for characterizing the chemical state andsymmetry of individual elements within materials,but requires collecting data at many energy points which can be time-consuming.While adaptive sampling methods exist for efficiently collecting spectroscopic data,they often lack domain-specific knowledge about the structure of XANES spectra.Here we demonstrate a knowledge-injected Bayesian optimization approach for adaptive XANES data collection that incorporates understanding of spectral features like absorption edges and pre-edge peaks.We show this method accurately reconstructs the absorption edge of XANES spectra using only 15–20%of the measurement points typically needed for conventional sampling,while maintaining the ability to determine the x-ray energy of the sharp peak after the absorption edge with errors less than 0.03 eV,the absorption edge with errors less than 0.1 eV;and overall root-mean-square errors less than 0.005 compared to traditionally sampled spectra.Our experiments on battery materials and catalysts demonstrate the method’s effectiveness for both static and dynamic XANES measurements,improving data collection efficiency and enabling better time resolution for tracking chemical changes.This approach advances the degree of automation in XANES experiments,reducing the common errors of under-or over-sampling points near the absorption edge and enabling dynamic experiments that require high temporal resolution or limited measurement time.
基金supported by the National Natural Science Foundation of China(Grant Nos.11574302,61474114,61674141,61504134,21503209&11704032)the National Basic Research Program of China(Grant Nos.2015CB921503,2014CB643503&2013CB632805)+1 种基金National Key Research and Development Program(Grant Nos.2016YFB0402303&2016YFB0400101)Key Research Program of Frontier Science,Chinese Academy of Sciences(Grant No.QYZDB-SSW-SLH006)
文摘Organic-inorganic hybrid perovskite materials have been receiving considerable attention due to their promising applications in many optoelectronic fields. However, the optical bandgap of CH3NH3PbI3 perovskite is still disputed. In order to comprehend the intrinsic characteristics of these materials, we study the near-band-edge optical responses of the solution-processed CH3NH3PbI3 perovskite crystals by photoconductivity and reflectance spectroscopy at room temperature. All these spectra of the CH3NH3PbI3 polycrystals show only one significant absorption edge at 1.58 eV. However, we observe an extra absorption edge at 1.47 eV in CH3NH3PbI3 single crystal. We establish a simple kinetic model of charge annihilation processes to explain why the low-energy structure of the photoconductivity and diffuse reflectance spectra of CH3NH3PbI3 polyerystals disappear, which provides another possibility for understanding the difference in absorption edge. It is noteworthy that this low-energy absorption edge of CH3NH3PbI3 single crystal has, to the best of our knowledge, seldom been reported on organic-inorganic hybrid perovskites. Therefore, the CH3NH3PbI3 single crystal exhibits a relatively wide absorption which makes it a promising candidate for photoelectric applications.
文摘Semiconductor(Zn\-\%x\%Cd 1-x S) doped silica glasses were prepared by Sol_Gel process and \%in situ\% growth technique. The structure of the materials was characterized by X_ray diffraction technique, the particle size of semiconductor crystallites from X_ray patterns was estimated less than 10 nm. From absorption spectra, it is obtained that the absorption edges shifted to short wavelength diraction when Zn contents increased, and the absorption edge can be adjusted from 2.46 eV to 2.96 eV by controlling Zn contents. The third_order nonlinear optical susceptibility was studied at 532 nm with 8 ns pulse laser by degenerate four wave mixing (DFWM) technique.
基金We thank the Photoemission Endstation （BL10B） in National Synchrotron Radiation Laboratory （NSRL） for collecting X-ray data. This work was supported by the National Key Basic Research Program of China （Nos. 2015CB351903 and 2014CB848900）, the National Natural Science Foundation of China （Nos. 21474095, 11574280, 11605201, and U1532112）, CAS Key Research Program of Frontier Sciences （No. QYZDB-SSW-SLH018）, and the Fundamental Research Funds for the Central Universities.
文摘Highly efficient and durable water oxidation electrocatalysts are critically important in a wide range of clean energy technologies,including water electrolyzers and rechargeable metal-air batteries.Here,we report a novel sonochemical approach to synthesize amorphous nickel-iron oxides/carbon nanohybrids with tunable compositions for the oxygen evolution reaction （OER）.The sonochemically synthesized amorphous electrocatalysts with optimal composition exhibit a low overpotential of 290 mV at 10 mA＆#183;cm-2 and a Tafel slope of 31 mV＆#183;decade-1 in a 0.1 M KOH electrolyte,outperforming the benchmark RuO2 catalyst.Meanwhile,these nanohybrids are also highly stable and remain amorphous even after prolonged cycling.In addition to amorphism,sonochemistry endows as-prepared nickel-iron oxides/carbon nanohybrids with a simultaneously formed carbon scaffold and internal Ni（0）,which can enhance the stability and activity for the OER.This work demonstrates that sonochemistry is a unique method for synthesizing amorphous metal oxides toward an efficient and durable OER.
基金Supported by National Natural Science Foundation of China (10775150)
文摘The total electron yield （TEY） mode has been developed successfully for XANES measurements at Beamline 4BTA of BSRF （Beijing Synchrotron Radiation Facility）. Its performance was studied by measuring sulphur K-edge XANES of three CdS samples （mixed with graphite powder as an electric conductor） with different concentration： 75%, 50~ and 25%. The data are collected in TEY mode and fluorescence yield （FY） mode respectively for comparison. The results demonstrate that the TEY spectra of three samples agree well with each other after the background is subtracted and normalized. The measured XANES spectra by TEY mode without bias and with 100V bias are almost identical to one another, but the signal-to-noise ratio of spectra measured without bias is better than that with 100V bias. The consistency of the self-absorption corrected FY spectra and TEY spectra are within 10% for the three samples.
基金Nuclear Researchers Exchange Program 2005Photon Factory Program Advisory Committee (2004G340)
文摘Thin silicon phthalocyanine dichloride films on HOPG were prepared and the sample was heated in the vacuum with laser. The thickness of the thin sample on HOPG was checked by X-ray photoemission spectroscopy. The orientation of the molecules in respect to the substrate plane was investigated by measuring the silicon K-edge near edge X-ray absorption fine structure （NEXAFS）. In the NEXAFS spectra of the thin sample, two clear peaks which were assigned to Is → σ^＊Si-N and 1s→ σ^＊Si-Cl appeared around 1847.2 eV and 1843.1 eV respectively. The intensities of the resonance peaks showed strong polarization dependence. A quantitative analysis of the polarization dependence revealed that the Si-N bond tended to lie down while the Si-Cl bond was out of the molecular plane.
