Determination of calcium in uranium by X-ray fluorescence

Summary An X-ray fluorescence method for the analysis of calcium in uranium in the range of 20 to 500 ppm is described. U₃O₈ samples are mixed with boric acid binder and double-layer pellets are prepared. The pellets are analysed using Philips PW 1220 semi-automatic X-ray spectrometer. Calculated lower limits of detection are better than 5 ppm for calcium in uranium.

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Bestimmung von Calcium in Uran durch Röntgenfluorescenz

Zusammenfassung Ein Verfahren für den Bereich von 20–500 ppm wird beschrieben. Die U₃O₈-Proben werden mit BorsÄure als Bindemittel vermischt zu Doppelschicht-Tabletten gepre\t, die mit Hilfe eines halbautomatischen Philips PW 1220 Röntgenspektrometers analysiert werden. Die untere Nachweisgrenze liegt bei 5 ppm Ca.

     

Determination of X-ray compression efficiency of a thin film X-ray waveguide structure using marker layer fluorescence

We demonstrate that a thin marker layer, sandwiched in the guiding medium of a thin film planner X-ray waveguide structure, can be used to determine X-ray compression efficiency for a particular excitation mode. It can also be used in evaluating the transmission efficiency of waveguide structure and for the determination of X-ray intensities reaching the waveguide exit. This approach has been applied for determining X-ray compression and transmission efficiency of a Mo/B₄C/Mo based X-ray waveguide structure, by inserting a thin Fe marker layer.     

Determination of low uranium concentration in carbonate-bicarbonate solutions by X-ray fluorescence

A method has been developed for the direct determination of uranium in carbonate solutions by X-ray fluorescence. Uranium, in the concentration range 0.2–50 ppm, is first absorbed as the carbonate complex on an anion exchange resin and then determined by X-ray fluorescence. A sensitivity corresponding to 20 ppb in 250 ml solution and a precision of ±6.5% was obtained. The sensitivity was 100-fold greater than that obtained by the direct determination in solution by X-ray fluorescence.     

Determination of lead and silver in copper blister by isotope excited X-ray fluorescence

The energy dispersive X-ray fluorescence method of Pb and Ag determination in metallic copper is described. Radioisotopic sources of⁵⁷Co and²⁴¹Am/target have been used for excitation and Si(Li) and hyperpure Ge spectrometers for spectra analysis. The standard deviation of Pb and Ag determination for a single measurement is 0.015 and 0.012%, respectively.     

Analysis of trace metals in thin silicon nitride films by total-reflection X-ray fluorescence

The validity of a matrix withdrawal method for the analysis of trace metals in silicon nitride films on silicon wafers by total-reflection X-ray fluorescence has been evaluated with samples contaminated with diluted standard solutions of eight metals (Ca, V, Cr, Fe, Ni, Cu, Ta, W). The nitride matrix was removed by a decomposition step with HF vapor at ambient conditions followed by the vaporization of the product at a temperature higher than 240°C. The recovery of added metals was determined first directly after vaporization and secondly after preconcentration by the droplet collection (DC) method. The recovery of metals after vaporization at a temperature of 300±50°C was generally close to 100%, except for Cu whose recovery was approximately 40%. The efficiency of the DC step was approximately 50% for most metals but only 10–20% for Cu and Cr. Thus for most metals the total recovery was close to 50%, which is acceptable for analytical purpose. The recovery of Cu and Cr was studied in more detail considering the influence of the thickness of the nitride film, the vaporization temperature, and the composition of the DC solution. The total recovery of Cu increased from approximately 10 to 40% by lowering the temperature of the vaporization step and using a more concentrated DC solution. The recovery of Cr by DC was markedly influenced by the thickness of the nitride film with no great benefit of using a more concentrated DC solution.     

Band gap tailoring of chemically synthesized lead sulfide thin films by in situ Sn doping

In the present report, undoped and tin (Sn)‐doped lead sulfide thin films were synthesized via chemical bath deposition method. The effects of Sn molar concentration on the optical, structural, and morphological properties were systematically studied. The concentration of Sn in the chemical bath was characterized by the ratio of [Sn⁺²]/[Pb⁺²] and varied from 0 to 15 at.%. Both doped and undoped thin films were polycrystalline in nature with a face‐centered cubic crystal structure; however, the preferred orientations of the crystallites were varied along the (111) and (200) planes with Sn‐doping concentration. The X‐ray powder diffraction results also showed that peak intensities and the crystalline size were decreased with increasing Sn concentration. The lattice constant varied with Sn concentration and found in the range of 6.020 to 5.944 Å. The variation of Sn concentration in PbS:Sn thin films were confirmed by energy dispersive X‐ray analyses study. The scanning electron microscope and atomic force microscopy studies revealed that Sn doping had a critical role on the surface roughness and morphology of the PbS:Sn thin films. The optical band gap study showed that the band gap of PbS:Sn thin films were engineered from 0.676 to 1.345 eV because of incorporation of Sn⁺² ions via cost‐effective chemical route. Room temperature photoluminescence spectra showed a well‐defined peak at 427 nm and shoulders at 405 and 462 nm for all Sn‐doped and undoped PbS samples.     

X射线荧光光谱法测定Zn镀层质量厚度及计算谱线选择问题研究

用X射线荧光光谱法测定了Fe基上Zn镀层的质量厚度；研究了厚度不同时选用不同谱线计算对测定结果的影响，发现在镀层质量厚度较小时（约〈14mg／cm^2）测量Zn元素的Kα线，质量厚度较大时选择Zn的Kα和Fe的Kα线共同计算，用纯元素和相似标样校正测定结果之间的偏差最小；用纯元素作校正标样测定了3个标准样品的Zn镀层质量厚度，计算结果与标准值符舍得较好。     

Speciation of activators in electroluminescent thin films: an EXAFS study of cerium and terbium doped strontium sulfide

Extended X-ray absorption fine structure (EXAFS) was used to determine the local structure of the luminescent centers in Tb³⁺ and Ce³⁺ -doped strontium sulfide thin films deposited by Atomic Layer Epitaxy (ALE). The rare earths were observed to enter mainly the substitutional sites but at the same time a part of the atoms form RES clusters (RE = rare earth). The presence of both substitutional sites and RES clusters has been observed for the first time in this study for rare earths in II–VI compounds. Received: 9 February 1998 / Revised: 22 May 1998 / Accepted: 29 May 1998     

Speciation of activators in electroluminescent thin films: an EXAFS study of cerium and terbium doped strontium sulfide

Extended X-ray absorption fine structure (EXAFS) was used to determine the local structure of the luminescent centers in Tb³⁺ and Ce³⁺ -doped strontium sulfide thin films deposited by Atomic Layer Epitaxy (ALE). The rare earths were observed to enter mainly the substitutional sites but at the same time a part of the atoms form RES clusters (RE = rare earth). The presence of both substitutional sites and RES clusters has been observed for the first time in this study for rare earths in II–VI compounds.     

Determination of Y,Ba and Cu in superconductor films by X-ray fluorescence analysis

Radionuclide X-ray fluorescence analysis was used for the determination of Y, Ba and Cu in thin high-temperature superconducting films. Atomic emission ICP spectrometry was used to estimate the precision and accuracy of analytical results. Reasonable agreement between both methods was obtained when a polynomial calibration curve was applied.     

三元硝酸盐预氧化熔融制样-波长色散X射线荧光光谱法测定锌精矿中锌、铜、铅、铁、铝、钙和镁

锌精矿属富锌、高铜、高铅的硫化矿矿物,硫和铜等元素腐蚀铂金坩埚是熔融制样-X射线荧光光谱分析必须解决的问题.在阶梯温度下,以硝酸铵、硝酸钠和硝酸锂的三元硝酸盐混合物为氧化剂,采用半熔法预氧化试料中的硫、铜、锌等元素,以四硼酸锂-偏硼酸锂混合熔剂(m:m=67:33)为熔剂、过饱和溴化锂溶液为脱模剂,于1050℃熔铸成X...     

Determination of lead in household refuse fly-ash by X-ray fluorescence spectrometry and a modified standard-addition technique

Lead in fly-ash from a garbage incinerator has been determined by X-ray fluorescence spectrometry (XRFS) and a modified standard-addition method. To keep the attenuation properties of the spiked samples constant, decreasing amounts of an attenuation modifier [mercury (II) acetate] were added together with increasing amounts of the standard (lead nitrate). Linearity between fluorescence intensity and amount of lead was thus obtained, so the amount of lead in the sample could be evaluated by linear regression. The amount of modifier needed could be calculated from a simple expression. The method was validated by comparison with the results obtained by applying atomic-absorption spectrometry (AAS) to solutions made by leaching the fly-ash with strong acid. For 8 fly-ash samples, containing between 0.8 and 1.35% lead, the largest absolute difference between the two sets of results was 0.03%. Theoretical calculations based on a simplified version of the Sherman equation were performed to confirm the linearity of the modified standard-addition curves.     

A correction method of matrix,density and thickness effects in thin samples analysed by X-ray fluorescence spectrometry

This paper deals with X-ray fluorescence spectrometry of powdered materials deposited on collection filters. The general applicability of this method is limited because the spectral response is affected by sample density and thickness and interelement effects may occur due to the specimen composition.The present work is aimed at contributing to the solution of the above mentioned problems, and reports a mathematical correction method which changes fluorescence intensity measurement data into fluorescence intensity values free from density and thickness effects. The correction of the thickness effect was obtained by overlapping the powder sample with a standard pellet containing some reference elements.The method allows the evaluation of the thickness of the unknown samples by measuring the intensity decrease of the X-ray fluorescence radiation coming from the reference pellet and passing through the unknown sample. These data are used to correct the intensity fluorescence values of the unknown samples.A computer program to elaborate spectral data by means of different and selected mathematical algorithms was set up.     

Multi-element X-ray fluorescence analysis of thin films using a mono-standard calibration procedure

Summary A semi-fundamental approach to calibration for multi-element X-ray fluorescence analysis of thin films is described. The curve, calibration line slope vs. atomic number, is calculated using known values for mass absorption coefficients, fluorescent yields and detector efficiency. This curve is then standardised for a particular matrix by determining the slope of at least one matched standard or via a standard addition procedure for one element. The technique is applied to the analysis of industrial waste water.

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Multielementanalyse von dünnen Schichten durch Röntgenfluorescenz mit Hilfe einer Monostandard-Eichmethode

     

Determination of thermal properties of some sulfide thin films using electropyroelectric method

Journal of Thermal Analysis and Calorimetry - This paper presents a simple theoretical model of a nondestructive electropyroelectric technique in front configuration to easily determine all static...     

X-ray fluorescence analysis of lead in leaves

The analysis of samples by means of X-ray fluorescence spectrometry has been used to monitor environmental pollutants in a collaborative project between the Department of Physics, the Centre for Materials Science of the University of Birmingham and latterly the University of Manitoba. Lead was chosen as the element of greatest environmental interest and the abundance of tree linedroads in the vicinity of the University suggested that leaves would be a conveninent sampling medium for the investigation of atmospheric lead concentration in areas of high traffic density.     

X射线荧光光谱法测定除尘灰中砷、铅含量

以熔融制样法,采用X射线荧光光谱对除尘灰中的有害元素：砷、铅含量进行了测定。对样品的烧失温度进行了讨论,发现在950℃灼烧温度下灼烧2h时除碳完全。砷和铅的相对标准偏差为0.15 %和0.20 %。测试结果与化学分析法、原子吸收光谱法等相吻合。该方法制作工艺简单,分析速度快,样品可长期保存,还能满足其他元素的日常分析。     

能量色散-X射线荧光光谱测定中草药痕量镉、铅、铜

为寻求一种能够直接对中草药中重金属进行快速检测的方法,采用压片法对样品进行前处理,建立了能量色散-X射线荧光光谱法快速检测中草药中痕量重金属镉、铅、铜元素的方法。在20 min即可完成检测,镉、铅、铜检出限分别为0.072、0.207、0.340 mg/kg,测试结果表明与原子吸收和ICP-MS相比,本方法数据稳定性和准确度良好,具有快速、准确、简单的优点,能够满足药典中对重金属元素的限量要求,适用于现场快速检测与质量控制检测。