2003 Vol. 27, No. S1
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The greatly stucture-sensitive characteristic of lead tungstate crystals (PWO) results in a complex defect phenomena inside.This research aims to clarify the mechanism of the annealing process and the doping mechanism of heterovalent ion doping in PWO from a viewpoint of microstructure-analysis.A variety of experiments were performed,including optical absorption spectrospcopy,impedance spectroscopy,X-ray photonelectron spectroscopy and EXAFS anaysis.Among them,EXAFS plays an important role for the availability to provide such structural informations as surrounding species,coordination number,and atomic distance.We report here the results of the defect-investigation in PWO crystals,conducted on the EXAFS experimental station of BSRL in 2002.
Experimental results of X-rays dose enhancement effects are given for floating ROM and SRAM with different integration from 16k to 4M irradiated by 20—100keV X rays in Beijing Synchrotron Radiation Facility and by cobalt source γ-rays.The ratio of radiation damage to the them irradiated with two sources are measured.The relationship of radiation hardness of SRAM versus different integration for γ-rays irradiation and the damage threshold values of X-rays for SRAM with different integration are presented.
We have measured Metal K-edge X-ray absorption spectra (XAS) and X-ray diffraction (XRD) spectra of transition-metal diborides (TiB2,VB2 and CrB2)We observed there are two weak pre-edge peak which may be separately due to hybridization between the 3d and 4p orbitals of the central metal atom and hybridization between the 3d orbitals of the cental metal atom and the coordinational metal atoms except two strong peaks in near-edge area.Moreover,we also simply fit the metal K-edge EXAFS spectra and got some structural parameters of the first and second shell of three transition metal absorption atoms.
Chromium(Ⅲ) can form mixed ligand complexes with amino-acids(glycine,glutamic acid,cysteine et al) and nicotinic acid.Chromium(Ⅲ) has been recognized as a trace element essential for both animal and human nutrition.The characteristics of local structures around Cr in chromium(Ⅲ)-amino acid-nicotinic acid mixed ligand complexes are investigated by EXAFS.The structural parameters of the nearest neighbors around Cr are obtained by simulating the first coordination peak in RSF.
In this paper,we probed the Acutolysin A—a Zinc protein purified from venom-by XAS technique,and its XAS curves in solution state of different pH values,were obtained.It was confirmed that the intense X-Rays didnt damage the samples during the experiment,and the curves among different pH values did present some differences.Through the comparison between simulated EXAFS curve based on PDB structure and an experimental signal,we concluded that the PDB data does not qualify for the fine structure research due to the limited resolution.At the same time,XANES analysis result could not reconstruct the experimental EXAFS curve either,because the PDB cluster used in the XANES calculation is free of Hydrogen atoms,therefore,a Hydrogen-contained cluster might be essential to the good fitting of XANES.
Microscopic structures of Zn(Ⅱ) surface complexes adsorbed at the manganite-water interface and δ-MnO2 water interface (in a 0.1M NaNO3 solution at 25°C )were studied using extended X-ray absorption fine structure (EXAFS) spectroscopy.Quantitative analysis of the EXAFS spectra showed that Zn(Ⅱ) was adsorbed onto the solid surface by sharing the oxygen atom in the hydrous Zn2+ ions and in the structural unit MnO6 on the manganite surface at pH7.5. Most of the adsorbed Zn(Ⅱ) was in the form of octahedral Zn(H2O)62+,but part of Zn(Ⅱ) was adsorbed as tetrahedral Zn(OH)2 or Zn(OH)42－.The average Zn-O bond length was 2.00±0.01A.EXAFS analysis of the second sphere indicated that Zn(Ⅱ) adsorbed on the manganite resulted in two Zn-Mn atomic distances of 3.08±0.02A and 3.54±0.02A,corresponding to the edge-linkage(stronger adsorption site) and corner-linkage(weaker adsorption site),respectively.The ZnO polyhedron was linked to the octahedron MnO6 of the manganite in these two modes by sharing two O atoms on the edges of the polyhedral and/or one O atom on the corners of the polyhedral.At pH 5.50,Zn(Ⅱ) was adsorbed onto δ-MnO2 surface in the form of octahedral hydrous Zn2+ ions.The octahedral Zn2+ was linked to the structural unit of octahedral MnO6 of the δ-MnO2 surface by sharing the O atoms.The average bond length of RZn-O was 2.07±0.01A and the Zn-Mn atomic distance was 3.53±0.01A,which corresponded to a corner-sharing linkage adsorption mode(weaker adsorption).Macroscopic adsorption-desorption isotherm experiments showed that,in contrast to that of Zn manganite,adsorption of Zn(Ⅱ) on δ-MnO2 was highly reversible and no apparent adsorption hysteresis was observed.EXAFS results indicated that the adsorption reversibility was corresponded to the corner sharing linkage mode or edge sgaring linkage mode between the adsorbate and adsorbent polyhedra.
The spectroscopic properties of SrBPO5 doped with Ce3+ ions are investigated in 130—400nm wavelength region.The bands corresponding to the 4f1→4f05d1 transitions of Ce3+ in the host lattices are identified.The barycenter of Ce3+ in the host lattice is found at 43.2×103cm－1,which is relative higher for Ce3+ in oxide.In addition,the host absorption and the crystal field splitting as well as the emission of SrBPO5:Ce3+ under VUV-UV excitation are presented and discussed.
High efficiency medical scintillator Lu2SiO5:Ce was studied by Synchrotron Radiation VUV spetra.The results show that two excitation bands in the range 250—320nm of powder sample become very weak in comparison with those of single crystal sample.The difference of the excitation band assigned to band to band transition between the two samples indicates that there are different defects in these two samples.Under VUV excitation (185nm),the emission spectrum of the two samples are similar.The emission band in the rage of 350—500nm corresponding to 5d→4f transitions of Ce3+.It can be decomposed to three sub-band which come from two types of Ce3+ luminescence centers.A new weak emission band was observed under VUV excitation.It possibly originates from the second type of Ce3+ luminescence centers of defect.
Spectroscopic properties of LiKGdF5:Er(2%),Dy(0.4%) single crystal grown by the method of hydrothermal synthesis were studied.The energy positions of absorption band for 4f105d of Dy3+ ions were determined through the measurement of excitation spectrum in the VUV region.The results show that the former is higher in energy than the later one.Under excitation into the 4f105d band of Er3+ ions,quantum cutting was archived and model presented.
We have measured the photon-energy dependence of the O 1s2p2p Auger line at the O K threshold,below Mn L2,3 edge of colossal magnetoresistance (CMR) materials Pr1-x Srx MnO3(PSMO) with x=0.0 and x=0.3 compositions.Experimental results show that the O 1s2p2p Auger peak splits and it can be best fitted to three component peaks.The relative intensity of the three peaks feature retain essentially similar values,in an experiment allowable error range of several percents,for both composition PSMO at O K threshold and below Mn L2,3 excitation.However,the total intensity has fluctuations indicating the feature of final state effect.This situation further changes drastically at above Mn L2,3 excitation energy by increasing the total intensity of x=0.3 system by a factor of 4 to that of x=0.0.These are discussed in terms of possible interatomic response and different valence band DOS for different PSMO compositions in the frame of covalent picture.
We have investigated thd C 1s X ray absorption spectra of graphite and contaminated single wall carbon nanotubes using surface sensitive photoelectron spectroscopy total electron yield mode.After annealing treatment in the ultra high vacuum system,the small feature which has been being ascribed to the so called free electron like interlayer states in between the characteristic π* and σ* conduction states has disappeared,confirming that the feature comes from the surface states,ie surface structural distortion and gas absorption,not form the free electron like interlayer states.Moreover,the intensity of π* and σ* peaks has changed considerably with this treatment,suggesting that it is necessary to treat the surface of the samples with annealing process in the comparison study of the DOS of the carbon nanotube materials.We have testified this argumentaltion by studying the DOS of the different samples of the contaminated single wall carbon nanotubes.
The microstructure and morphology of Ge quantum dots grown on Si(001) with varied coverage of Si caplayer has been studied by grazing incident eiffraction (GID) and atomic force microscpe(AFM) respectively.It is found that the composition as well as the morphology varies obviously with small change of coverage of Si caplayer.
We report our recent experimental results on solid-liquid interfaces.A set-up for X-ray scattering from the liquid -solid interfaces has been successfully installed at the Diffuse Scattering Station of the Beijing Synchrotron Radiation Facility.The samples were prepared by evaporation of isopropanol solutions of 10,12-Tricosadiynoic acid (TCDA) deposited on clean silicon surfaces.The in situ X-ray measurements for a long time .The linear elastic theory of liquid crystals can account for the thermal fluctuations of the bilayers only on large scales.The deviation form the linear elastic theory is attributed to the existence of defects in the multilayers.This hypothesis is supported by the observation that polymerization enlarges the displacement field of the defects.
The low-resolution shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter sphaeroides 2.4. 1 in detergent solution has been determined from synchrotron small-angle X-ray scattering (SAXS) data using directly curve fitting by an ellipsoid and ab initio shape determination method or multipole expansion respectivelv. The results indicate that the LH2 proteins in aoueous solution has a shape of oblate plate. In contrast to the perfect symmetrical ring-like structure of LH2 in crystalline, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ring-like crystal structure, which is consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules.
The suspension colloids of the wide-gap semiconductor TiO2 nano-particles in aqueous solution at elevated temperature have been studied by in situ small angle X-ray scattering using synchrotron radiation.It is found that the Guiner plot of the scattering intensity shows an upward concave behaviour at lower scattering vectors,being representative of a polydispersive system.The size distribution of gyration radius of TiO2 nano-particles in aqueous solution,M(Rg),has been successfully determined by Shull-Roess method.The main peak of M(Rg) at 25°C is located at 2.3nm,corresponding to a spherical diameter of 5.9nm,while it increases to 3.2nm at 80°C,correspoding to a spherical diameter of 8.2nm.This size distribution of TiO2 nanoparticle in solution is useful to understand the photo-electron properties and the stabilities of the dye sensitised TiO2 nanoparticle solar cell.
We measured the X-ray small angle refection (XRR) in Beijing Synchrotron Radiation facility (BSRF) and the Doppler broaden of positron in Beijing slow positron beam with 22Na radiation source for pore SiOx(1≤x≤1.6) film prepared by radio-frequency sputtering at different Ar pressures.The result of XRR showed that with the Ar pressures increasing,densities of films were decreasing and porosity were increasing.Positron annihilation result S parameters were decreasing with Ar increasing,this contributed to the paramagnetic defect E' center reducing Ps production.Comparing with the thickness of films with XRR method and slow positron annihilation analyzing program VEPFIT,it showed that the results were consistency and the result of VEPFIT was samller.
Perovskite type compounds of general formula ABX3 have the most commonly adopted structure (Pbnm),to some extent distorted from the ideal structure Pm3m.Their structures transformations are diverse at high pressure.Three parameters (t,VA/VB,Etot),which are used to describe the stabilization of perovskite structures,are introduced briefly.Applied threeparameters,all models of perovskite structure (Pbnm) changing at high pressure are summed up.Some of the models suit all perovskites structures.As an example,CaTiO3 (Pbnm) structure changing at high pressure is analyzed by applying several models and qualitatively draws a conclusion that the structure symmetry is reduced with enhancing the pressure.
Unique sampling assemblages were designed to investigate elemental mobility of the systems of plagioclase amphiblite-CaCO3(-H2O) on the conditions of ultrahigh pressure contact metamorphism of eclogite phase.The experiments were carried out using multianvil apparatus at pressures of 4.5 and 5.5 GPa and temperatures of 800 and 1100°C for 6 to 16 hours respectively.The columniform samples after ultrahigh pressure contact metamorphism were sliced and polished along the axes.After observed by SEM,the samples were investigated by synchrotron radiation X-ray fluorescence (SPCRF) method. The SRXRF results indicate that the mobility of Ca,Sr and Fe is decreased with increasing pressure,and the effect of temperature is reversed and low than that of pressure.The Sr mobility in the process of ultrahigh pressure metamorphism is faster than that of Ca and Fe which is similar,this means that Sr would separate from Ca.H2O accelerates greatly the elemental mobility rate,and its effect exceed greatly that of CO2,which is as such the most important fluid composition in the deep Earth.
Phase-contrast imaging with synchrotron X-ray has great potential to reveal the structure inside soft tissues,because the sensitivity of this method is≈1000 times higher than that of the absorption-contrast X-ray method.With a synchrotron X-ray source,bronchia tree and the image created by multiple layer of alveoli in the mouse lung was revealed clearly.The results indicate that the considerable potential of phase-contrast imaging with synchrotron X-ray in the detection of pathological changes of lung which can't be detected by conventional absorption-contrast X-ray method.
X-ray fluorescence holography is a novel method for three-dimensional (3D) imaging of local atomic structure.Theoretically,in an XFH experiment,one has to measure the fluorescence energy on a spherical surface with angular resolution in the degree range to get well-resolved three-dimensional (3D) images of atoms.But in practice,experimental system arrangement of XFH does not allow the measurement of the fluorescent intensity oscillations in the full sphere.The holographic informaion loss because of the limited sampling range (less than 4π) will directly result in defective reconstructed atomic images.In this work,we investigate the influence of angle range and step of recording an X-ray fluorescence hologram on reconstructed atomic images by numerically simulating X-ray fluorescence holograms of Fe single crystal at different recording angle range and step.The Fe atomic images in the plane parallel to the crystal (001) crystallographic plane reconstructed from these simulated holograms can show this influence.The incomplete range of azimuth angle causes inhomogeneous brightness of the reconstructed atomic images.The incomplete range of polar angle causes the reconstructed atomic positions slightly shifted toward the central site and the increase of background brightness.The influence of the polar angle step on the reconstructed atomic images can be ignored if the step is enough small.
Crystal defects in large synthesized diamond grain were studied with X-ray topography using white synchrotron radiation.Several bundles of straight stretching dislocations were observed in the specimen.The direction indices of these dislocations in the crystal were calculated.The five dislocation bundles are parallel with <100> and <110> directions,respectively.The Burgers vectors of the dislocations were analyzed.Each bundle of the dislocation was composed of many dislocations with different Burgers vectors.A bundle of dislocations parallel with <100> direction were found in the crystal that has never been observed in the natural diamond before.The complexith of the Burgers vector and the presence of the metastable dislocations in the specimen were discussed.
The major and trace elements in the bodies and glazes of ancient colored glazes were determined by Synchrotron Radiation X-ray Fluorescence (SRXRF).The ancient colored glazes were unearthed from the stratums of Song,Yuan,Ming,Early Qing and Late Qing dynasty in Shanxi province.Multivariable statistical analysis of the experimental data were carried out by SPSS software.The result indicate the chemical compositions in the bodies are stable in samples from Song to Early Qing dynasty,but have distinctly difference from that of Late Qing dynasty.Those results are consistent with the conclusion by INAA method.The primary colored elements are Fe,Cu and Co for these samples.The colors variety of glazes are due to the change of those three elements concentrations.
The ancient celadon that made in the period from Late Tang Dynasty to Southern Song Dynasty(900—1200A.D.)were excavated in Yue kiln,Zhejiang province of China.This paper studied elemental consititute of Yue kiln glaze by synchrotron radiation X-ray fluorescence (SRXRF) with ono-destructive analysis.The feasibility of ono-destructive analysis method was also discussed.We analyzed ancient celadon samples of 6 cultural periods that produced from Yue kiln of Si Long Kou,the celadon of He Hua Xin kiln where is about 5 km to Si Long Kou kiln were used to contrast the provenance performance.The statistical analysis of elemental abundances indicated that most of celadon samples belong to their corresponding production age,which evidently reflects the Yue kiln characteristics.There was age correlation among the ancient celadon of special cultural period.
The microanalysis very useful in various scientific regions.Microanalysis reference material(MRM) is important for quantiatative analysis and quality control.The minimum analytic mass of the presented testified standard material is 100mg.It is indispensable to study a microanalysis reference material.Asolid powder 99% in size of 500 mesh for microanalysis reference material (MRM) has being prepared.The minimum analytic masses of 1 mg were determined by SRXRF for elements (K,Ca,Ti,Mn,Fe,Zn,Rb,Sr).
Yuerya gold deposit,lying in the Eastern of Hebei Province,China,is the typical one of the gold deposits related to Mesozoic granite and forming under the action of low-middle hydrothermal liquids,in which pyrite-muscovitequartz mineralization is an important indicator to gold.Chemical composition of muscovite from this deposit was investigated with synchrotron radiation X-ray fluorescence (SRXRF) in this article.It is showed that the muscovite contains many elements including K,Ca,Rb,Cr,Mn,Fe,Co,Cu,Zn,Au,Ag,Pt and As.Correlation factor analyses of these elements show that gold is not only correlated with muscovite composition elements,but also correlated with Pt and As which are with no correlation to the muscovite composition elements,which show gold in muscovite has two existing formations and at less two different resources.Mineralization resources is commonly considered as magma hydrothermal liquid,but platinum firstly found in Yuerya gold deposit,supports the idea of gold mineralization partly related with mantle-derived material.
Mn2+-enhanced magnetic resonance imaging is very useful for mapping the olfactory bulb,but has poor positional resolution(～100μm)and difficulty with the quantitative analysis of Mn.Synchrotron Radiation X-ray Fluorescence(beam size ～20μm,detect on limit of Mn ～10－11g) and Energy Disperse X-ray Fluorescence combined with multi-variable statistics were employed to investigate the positional distribution of manganese and other elements in slices of the olfactory bulk of SD rats.The naris of rats were pipetted with MnCl2 (Mn group n=4) compared with the control group (n=3).Our results show that the manganese distributions in the slices of both groups were non-homogeneous.The difference in the contents of Mn of rats treated with MnCl2 is as high as 50 times.Rats treated with MnCl2 exhibited a strong correlation (0.985,p=0.000) between the positional distribution of Mn and Ca,and the contents of Mn,Ca,Zn and Br of the Mn group were 55%,82%,42% and 72% higher than the control group.
Because of its validity in reducing transistor noise due to gate parasitic resistance,T-shaped structure has been applied for the fabrication of Pseudomorphic High Electron Mobility Transistor (PHEMT) device widely,X-ray lithography is the best way to fabricate deep-submicron T-shaped structure,because it has many adantages,such as large process latitude、high throughput,extremely long depth of focus、large exposure field sizes,low cost,and so on,and the more important thing is that X-ray lithography technology is relatively mature.In this paper,the home-made X-ray mask process is introduced first,and the influence of blur to the light intensity distribution on the surface of X-ray resist is analyzed,the three layer resist method which is used for the fabrication of deep-submicron T-shaped structure and the 75nm T-shaped structure result which was achieved in BSRF 3B1A beamline are presented lastly.
Photoconduction detector has advanced features of small volume,high sensitivity and wide application range,but the noise current of it is high.So it is difficult to calibrate the detectors sensitivity.We have calibrated a few of PCDs by the way of electronics on Beijing Synchronization Radiation Facility (BSRF) and obtained the sensitivity curve at 50—300eV energy range.The way we used has been proven a good way from the experimental results.
Beamline 3B1B is a VUV beamline in Beijing Synchrotron Radiation Laboratory,it was designed for studies on VUV fluorescence spectroscopy and VUV Circular Dichroism spectroscopy of biological macromolecular.Due to the very small acceptance and bad vacuum,the beamline didnt fulfill the experiments well in past years.A new VUV beamline was designed since 2001,the photon energy range is from 120nm to 350nm.1 meter Seya-Namioka monochromator was selected for new 3B1B beamline because of the good performance and wide use in VUV ultraviolet beamline,the entrance slit and exit slit can be fixed when the different wavelength can be selected.In the paper,design and performance of the monochromator is introduced,also the calibration of the monochromator is presented.
The paper brief introduces the general situation of two new permanent multipoles wigglers are designed and constructed in Beijing Electron Positron Collider (BEPC) as a part for the BSRF upgrade project.The magnetic and mechanical design of two wigglers be described in this paper.Also given are the design parameters and the characteristics of the synchrotron radiation for the wigglers.
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