基于基本参数法的EDXRF全谱拟合定量算法及其应用

在进行能量色散X射线荧光（EDXRF）的解谱操作时,如果样品中元素含量不高,单个元素的谱峰形状在混合样品谱中会保持较好,纯元素谱剥离是一种比较好的解谱方法,同时,在不高的含量范围内,谱峰强度与元素含量的线性关系保持较好,定量较为准确;但在常量分析中,元素之间会存在较强的吸收增强效应,并导致混合样品谱中单个元素的贡献与其纯元素谱的形状不一致,因此,用固定形状的纯元素谱剥离方法就会有较大偏差。同时,吸收增强效应会干扰谱峰强度与元素含量的线性关系,两种因素的叠加,导致元素定量的不准确,因此,在进行常量分析时,简单的纯元素谱剥离的解谱方法并不适用。介绍了一种基于基本参数（FP）法的全谱拟合定量算法,在进行谱图准确拟合的同时,完成定量计算,其操作步骤如下：首先用纯元素谱剥离的方法得到实测的各谱线强度,并以此为依据预估样品中各元素含量,然后代入FP法计算样品中各谱线理论强度,根据与实测值的偏差调整元素含量,并做“FP计算-调整含量”两个过程的迭代,直至计算谱与实测谱的强度无差别;用最后的样品构成计算各元素谱峰形状,并修正纯元素谱,再次重复“剥离解谱-估算含量-迭代FP计算”的步骤,将最终得到的元素含量认为是测试结果。该种方法弥补了简单解谱剥离方法的弊端,借助于基本参数法的计算,纯元素谱峰得到了修正,解谱更准确,同时也能很好地校正基体效应对定量分析的影响。利用这种方法对较高浓度La/Ce/Pr/Nd混合溶液样品的EDXRF谱图进行分析,新方法计算得到的谱图与实测谱的残差σ降至474.5,远小于单纯使用纯元素谱剥离方法的1 415.0[1]。用该方法对多个配分含量范围从0~90%的稀土混合溶液进行检测,各样品各元素配分偏差均小于1%,多次连续测试表明,各元素的相对标准偏差RSD<1%,该方法的准确度和稳定性都较好,能很好地满足稀土冶炼行业生产实践的需求。     

Mass spectrometry of rhenium complexes: a comparative study by using LDI-MS, MALDI-MS, PESI-MS and ESI-MS

A group of rhenium (I) complexes including in their structure ligands such as CF(3)SO(3)-, CH(3)CO(2)-, CO, 2,2'-bipyridine, dipyridil[3,2-a:2'3'-c]phenazine, naphthalene-2-carboxylate, anthracene-9-carboxylate, pyrene-1-carboxylate and 1,10-phenanthroline have been studied for the first time by mass spectrometry. The probe electrospray ionization (PESI) is a technique based on electrospray ionization (ESI) that generates electrospray from the tip of a solid metal needle. In this work, mass spectra for organometallic complexes obtained by PESI were compared with those obtained by classical ESI and high flow rate electrospray ionization assisted by corona discharge (HF-ESI-CD), an ideal method to avoid decomposition of the complexes and to induce their oxidation to yield intact molecular cation radicals in gas state [M](+·) and to produce their reduction yielding the gas species [M](-·). It was found that both techniques showed in general the intact molecular ions of the organometallics studied and provided additional structure characteristic diagnostic fragments. As the rhenium complexes studied in the present work showed strong absorption in the UV-visible region, particularly at 355?nm, laser desorption ionization (LDI) mass spectrometry experiments could be conducted. Although intact molecular ions could be detected in a few cases, LDI mass spectra showed diagnostic fragments for characterization of the complexes structure. Furthermore, matrix-assisted laser desorption ionization (MALDI) mass spectra were obtained. Nor-harmane, a compound with basic character, was used as matrix, and the intact molecular ions were detected in two examples, in negative ion mode as the [M](-·) species. Results obtained with 2-[(2E)-3-(4-tert-buthylphenyl)-2-methylprop-2-enylidene] malononitrile (DCTB) as matrix are also described. LDI experiments provided more information about the rhenium complex structures than did the MALDI ones.     

Effects of the structural state of a W — Re solid solution on the Fe-57 Mössbauer spectrum

Mössbauer spectra for iron-57 are reported for alloys containing up to 27 at.% rhenium. The cobalt-57 was introduced by diffusion annealing as the parent isotope for the iron-57. Diffusion annealing at 1080°C for 16 hr causes the cobalt to diffuse mainly along lattice defects (dislocations and grain boundaries). These defects give rise to regions whose electronic structure differs from that of the matrix. The precise type of structure and the number of such regions are complex functions of the alloy composition and structural state. Results are given on the iron-57 spectra for tungsten, rhenium, the σ phase, and an alloy in the two-phase region.     

Total electron yield mode for XANES measurements in the energy region of 2.1-6.0 keV

The total electron yield (TEY)mode has been developed successfully for XANES measurements at Beamline 4B7A 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.     

Auger spectroscopy of polyethylene and poly (ethylene oxide)

The X-ray excited Auger spectra of polyethylene and poly(ethylene oxide) have been corrected for Auger electron energy losses due to interactions with the solid and compared to the corresponding spectra of gas phase molecular analogs. The corrected polyethylene spectrum is an extrapolation of trends observed in the spectra of gas phase alkanes from CH₄ through C₆H₁₄. The O(KVV) spectrum of poly(ethylene oxide) is similar to that of methyl ether, consistent with similar nearest neighbor environments for the oxygen atoms in the two materials. In contrast, the C(KVV) spectrum of poly(ethylene oxide), a material which contains C-C bonds, is better approximated by the spectrum of ethane (H₃C-CH₃). A comparison of the polyethylene Auger spectrum with the spectra of the normal alkanes and with a self-fold of its X-ray excited valence band photoemission (single hole) spectrum indicates the presence of correlated two-hole final states in the case of polyethylene.     

铼的弹性剪切参数C44对温度与压力响应的原位拉曼光谱研究

铼具有高体积弹性模量、高熔点、优良的抗蠕变性能,是一种重要科学研究与工程应用材料。铼的弹性剪切系数C₄₄对温度和压力的响应特性对铼及其合金材料的设计与工程应用具有重要意义。激光拉曼散射技术在研究不同温度和压力条件下六方密堆积结构(hcp)金属的弹性剪切系数C₄₄上具有独特的优势。但由于金属的强反射作用和浅的穿透深度,hcp金属的低波数拉曼散射信号往往很难获取,在一定的温度和压力加载下拉曼信号的获取尤为困难。利用侧向激发拉曼散射技术,有效降低了金属强反射对拉曼光谱采集的影响,成功测量到多晶铼在不同压力与温度条件下的E_2g拉曼振动模,获得铼在常温常压条件的弹性剪切系数(C₄₄=133 GPa)以及其弹性剪切系数C₄₄对温度和压力的响应特性。研究结果表明,多晶铼的弹性剪切系数C₄₄模量随压强的增加而增大,随温度的增加而减小。这也为用光散射方法研究金属材料剪切模量提供了良好研究方法。     

High pressure generation using double-stage diamond anvil technique: problems and equations of state of rhenium

We have developed a double stage diamond anvil cell (ds-DAC) technique for reproducible pressure by precisely fabricating 2nd stage anvils using a focused ion beam system. We used 2nd stage micro-anvils made of ultra-fine (V/V₀?=?0.633 for the smallest d-spacing. The calculated pressure for this minimum volume varies from 430 to 630?GPa, depending on the choice of the equation of state of rhenium. We conclude that the most likely pressure achieved for the minimum volume of rhenium is in a range of 430–460?GPa based on a calibration using the platinum pressure scale to 280?GPa and the latter value of 630?GPa is unreasonably high, suggesting that the pressures in an earlier study for the equation of state of rhenium would have been significantly overestimated.     

去除土壤水分对高光谱估算土壤有机质含量的影响

土壤高光谱技术具有方便快捷、无破坏、成本低等优点,已被广泛应用于估算土壤有机质含量(SOMC)。然而,野外测量的土壤高光谱数据因受外部环境因素(土壤湿度、温度、表面粗糙度等)干扰,导致SOMC估算模型适用性有待提升。土壤含水率(SMC)是影响野外测量高光谱的最主要的障碍因素之一,它的变化严重影响可见-近红外(Vis-NIR)光谱反射率的观测结果。因此,消除SMC对高光谱数据的干扰是提高土壤高光谱估算SOMC模型预测精度的关键环节。以江汉平原潜江市潮土样本为研究对象,在室内人工加湿土样,分别获取6个SMC水平的土壤高光谱数据,采用标准正态变换(SNV)对光谱数据进行预处理,基于外部参数正交化法(EPO)去除土壤水分对高光谱的影响,利用偏最小二乘方法(PLSR)建立并对比EPO处理前、后不同SMC水平SOMC反演模型。结果表明,土壤水分对Vis-NIR光谱反射率有显著的影响,掩盖了SOMC的光谱吸收特征;EPO处理前不同SMC水平的光谱曲线之间的差异较为明显,而EPO处理后的各SMC水平的光谱曲线形态基本相似;采用EPO处理后的土壤高光谱数据建立SOMC估算模型,预测集的R2_p,RPD分别为0.84和2.50,其精度与EPO处理前所建模型相比有较大提升,表明EPO算法可以有效去除土壤水分的影响,从而提升SOMC的估算精度。对定向去除外部环境参数对土壤高光谱影响进行了实证,为完善野外原位获取SOMC信息技术提供理论基础。     

0.23 eV energy resolution obtained using a cold field-emission gun and a streak imaging technique

We demonstrate that a high energy resolution of 0.23 eV is possible by using a cold field-emission electron gun (CFEG) without a monochromator. We have used a 300 kV transmission electron microscope (Hitachi, HF-3000) equipped with a CFEG and an energy filter (Gatan, GIF2002). Since energy instability is critical for high energy resolution in electron energy-loss spectroscopy, we have applied a high-speed 'streak imaging' acquisition technique, in which a series of time-resolved spectra are acquired as a two-dimensional spectrum. With this technique, we can easily record 1000-20,000 spectra with an exposure time of 0.353 ms per spectrum. Instability of less than 1.4 kHz has been corrected in the time-resolved spectra, allowing the inherent performance of the CFEG to be realized.     

不同部位矿质元素与红外光谱数据融合对美味牛肝菌产地溯源研究

野生食用菌产地溯源研究中,采用单一有机成分或矿质元素指纹存在一定局限性。利用不同指纹分析技术的互补性与协同性,将不同部位与类型的化学信息进行融合,探讨此方法对野生食用菌产地溯源的可行性,以期为野生食用菌溯源提供新的思路与科学依据。通过测定云南7个产地、124个美味牛肝菌(菌柄、菌盖)中15种矿质元素的含量,以及子实体傅里叶变换红外光谱(FTIR)。标准正态变换(SNV)、二阶导数(2D)等算法对原始光谱进行预处理。基于低级与中级数据融合策略,将预处理后的FTIR光谱与菌柄、菌盖矿质元素数据进行融合,结合支持向量机(SVM)分别建立菌柄、菌盖、FTIR、低级数据融合(菌柄+菌盖,菌柄+菌盖+FTIR)与中级数据融合(菌柄+菌盖+FTIR)判别模型;分析比较模型参数,确定快速甄别美味牛肝菌产地的可靠方法。结果显示：(1)菌盖中Cd,Cr,Cu,Li,Mg,Na,P和Zn元素平均含量高于菌柄,Ba,Ca,Co,Ni,Rb,Sr和V元素在菌柄中平均含量高于菌盖。美味牛肝菌中人体必需矿质元素Ca,Cu,Mg,P和Zn平均含量远高于小麦、水稻干品和新鲜蔬菜,与动物干制品含量相似;(2)FTIR光谱数据最佳预处理方法为3D+SNV,其Q2和R2Y分别为76.64%,88.91%;(3)菌柄、菌盖、FTIR、低级数据融合与中级数据融合SVM模型,c值分别为8 192,4 096,1.414 2,11.313 7,1和0.7071 1,菌柄和菌盖模型c值较大,表明采用单一菌柄或菌盖矿质元素含量数据,SVM训练存在过拟合风险,判别效果较差;(4)FTIR、低级数据融合和中级数据融合SVM模型,样品分类错误总数分别为7,9,7和0,中级数据融合(菌柄+菌盖+FTIR)模型样品分类正确率最高。表明基于中级融合策略将不同部位矿物元素和子实体FTIR光谱数据融合,可作为野生食用菌产地溯源的一种有效方法。     

The ignored discovery of the element Z = 43

Until now Perrier and Segrè (Palermo, 1937) are credited for the first observation of the element Z = 43, called technetium (Tc). We give arguments for the statement that Walter Noddack, Ida Tacke and Otto Berg (Berlin, 1925) should be credited for the discovery of this element. In their search for the missing eka-manganese elements with Z = 43 and Z = 75 they observed the X-rays of these elements, with the peculiar behaviour though that the Z = 43 lines only appeared in ores, quoted to contain percentage quantities of uranium. The presence of element Z = 43 in uraniumcontaining ores can now be explained through the long-living fission product ⁹⁹43 in their samples; they proposed the names masurium (Ma) and rhenium (Re) for the discovered elements. By reanalysing the original experimental conditions, we conclude that the detection limit for their observing the X-rays of Z = 43 can be 1000 times lower than the 10⁻⁹ detection limit for the element Z = 75. This brings us very close to the expected abundance of Z = 43 in the analysed samples, such that we do not see reasons for questioning the credibility of the experimental evidence.     

Induced Quasi-Dynamic Disorder in a Structure of Rhenium Ion-Implanted Quartz Glass

Physics of the Solid State - The ultraviolet (UV) absorption spectra were studied in UV–Vis–IR quartz glasses exposed to the rhenium ion irradiation at the energy of 30 keV. An increase...     

Feasibility of estimating copper content using visible and near-infrared spectra of bedrock,weathered rock and soil - a case study of the Baogutu stock II,Xinjiang, China

Geochemical anomalies are important symbols for prospecting. To determine a new method for identifying geochemical anomalies rapidly, this study examines the possibility of using visible and near-infrared spectra of bedrock, weathered rock, and soil to assess copper content in the Baogutu stock II, Xinjiang, China. Partial least squares regression was employed to study the relationship between visible and near-infrared spectra and the ore-forming element contents of collected bedrock samples, weathered rock samples, and soil samples. More specifically, our study aims to achieve three objectives. First, to explore the correlations between the contents of different elements and the correlations between the visible and near-infrared spectra and the ore-forming element contents for the three sample types. Second, to evaluate the performance of the reflectance-based partial least squares regression model. The models for iron in bedrock samples and copper in soil samples were chosen for estimating copper content. Third, to assess the effectiveness of data transformation methods in the partial least squares regression model. In our case study, the square root-based models for iron in bedrock samples and copper in soil samples with coefficients of determination for prediction are 0.614 and 0.409 respectively, maximized the model performance. Therefore, it is evident that visible and near-infrared spectra can be an alternative method for estimating ore-forming element contents based on bedrock, weathered rock, and soil samples.     

Studies of transverse chromatic aberration based on individual eye model

Two kinds of individual eye models, with and without involving the angle between visual axis and optical axis, are constructed according to the measurements of the corneal surfaces, the optical axis lengths and wavefront aberrations. The constructed eye models are then used to investigate the properties of the transverse chromatic aberration (TCA) and its influence on visual performance. The statistical distributions of the horizontal TCA, vertical TCA and the absolute magnitude of the TCA over the spectrum from 470 to 650 nm are provided, respectively. The variations of TCA with wavelength as referring to the central wavelength of 555 nm for five subjects are also provided. Then we evaluate the impact of TCA on image performance in comparison with longitudinal chromatic aberration (LCA). It is shown that LCA is more detrimental than foveal TCA in image quality. It is found that, while LCA was corrected well, the foveal TCA is simultaneously corrected. Finally, we investigate the correction of peripheral TCA with an achromatizing element. The correction of peripheral TCA of human eye strongly depends on the location of the achromatizing element, and with the element in front of the eye, the peripheral TCA cannot be corrected.     

Theoretical photoelectronic spectra of molybdenum, tungsten, and rhenium disilicides

Photoelectronic spectra of volume samples of molybdenum, tungsten, and rhenium disilicides are theoretically investigated as functions of the excitation energy (hv = 12–1486 eV) by the method of linearized attached plane waves. The main contribution to the spectrum at low (hv = 12–52 eV) and very high (hv = 1486 eV) excitation energies is given by the metal d-states, while the contribution of the Si p-states is dominant at intermediate excitation energies. An analysis of the calculated results demonstrates that the main peak of the photoelectronic spectra is displaced by 0.2 eV toward the bottom of the valence band when going from MoSi₂ to WSi₂; it is displaced by 0.3 eV when going from WSi₂ to ReSi_1.75. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 75–80, July, 2006.     

Synthesis of magnetic rhenium sulfide composite nanoparticles

Rhenium sulfide nanoparticles are associated with magnetic iron oxide through coprecipitation of iron salts with tetramethylammonium hydroxide. Sizes of the formed magnetic rhenium sulfide composite particles are in the range 5.5-12.5 nm. X-ray diffraction and energy-dispersive analysis of X-rays spectra demonstrate the coexistence of Fe₃O₄ and ReS₂ in the composite particle, which confirm the formation of the magnetic rhenium sulfide composite nanoparticles. The association of rhenium sulfide with iron oxide not only keeps electronic state and composition of the rhenium sulfide nanoparticles, but also introduces magnetism with the level of 24.1 emu g^-1 at 14 kOe. Surface modification with monocarboxyl-terminated poly(ethylene glycol) (MPEG-COOH) has the role of deaggregating the composite nanoparticles to be with average hydrodynamic size of 27.3 nm and improving the dispersion and the stability of the composite nanoparticles in water.     

X-ray tube spectra measurement and correction using a CdTe detector and an analytic response matrix for photon energies up to 160 keV

The aims of our work were: i) to measure selected normalized X-ray beam spectra with the commercially available cadmium telluride detector based spectrometry system; ii) to construct the approximate response matrix of the detector using a simple algebraic model approach; iii) to reconstruct the physical energy spectra from the measured instrumental spectra using the detector response matrix; iv) to compare the obtained spectra parameters with the published and reference data in order to verify the model and to optimize the measurement setup if necessary. In particular, the spectra of five “narrow-spectrum series” beams, namely N60 to N150, were measured with a spectrometry system consisting of the Amptek XR-100T X-ray semiconductor detector and the PX5 multichannel analyser. Two different measuring geometries were used. The response matrix R(E, E′) of the detector was constructed which quantifies the energy dependence of the relative detection efficiency of the detector, the probabilities of the escape effects, and the probability of the Compton effect. A single matrix operation was applied to recover the physical energy spectra from the measured instrumental ones. The parameters of the corrected spectra were compared with the published and reference data. Despite the fact that the effect of incomplete charge collection was not implemented in the detector model, a fully satisfying quantitative correspondence was observed between the measured corrected spectra and the available reference data.     

Was the ”first“ angle-resolved photoemission experiment done by a nobel-prize winning physicist at adelaide university in 1908?

Scientific ideas and techniques grow and develop with time, and it is usually unrealistic to label a ”first“ experiment of any kind. Nevertheless, there are reasons to suggest that an experiment done by a famous physicist in Adelaide (South Australia) in 1908 provided the initial impetus for 30 years of angle-resolved photoelectron spectroscopy research during the years 1908–1938. The present paper focusses on the years before World War I (1904–1914), and highlights a piece of work previously remembered for different reasons.     

Copper coordination hypotheses and atomic arrangement in the glassy alloy Cu0.25As0.30Te0.45

Summary The radial atomic distribution of the amorphous alloy Cu_0.25As_0.30Te_0.45 was studied, through the X-ray diffraction data supplied by samples obtained through quenching. The short-range order was determined by interpreting the radial distribution function (RDF), using a theoretical expression which takes into account the variation in the atomic scattering factors withs (the scattering vector module), and approximates them to polynomic functions. The tetracoordinated copper hypothesis, quoted in the literature for glassy alloys containing this element, was considered. The result of the study is that, for the alloy in question, the tetracoordinated copper hypothesis is compatible with the structural information that was experimentally obtained. A spatial atomic distribution model was generated according to this copper coordination, using the conveniently modified Monte Carlo random method. A comparative analysis of the main structural parameters of this model revealed their good agreement with the values given in the literature for similar alloys.