Wavelength Dispersive X-ray Spectrometer Research Articles

Microstructure of Nd-rich phase in Nd-Fe-B magnet containing oxygen and carbon impurities (abstract)

The microstructures of Nd-Fe-B magnet were examined by scanning electron microscopy (SEM) with wavelength dispersive x-ray spectrometer (WDS) specially equipped lead stearate crystal for lighter elements detection. Investigations were performed on the samples of (Nd0.9Dy0.1)15FebalB8 magnets with various oxygen and carbon content. Oxygen and carbon were added to the alloy, because magnetic properties were extremely influenced by these elements and commercial magnets could not be produced without these impurities. SEM observations revealed a complex microstructure of Nd-rich phase1,2 in grain boundary junctions. Nd-rich phase principally consists of two different phases. One is Nd-rich phase absorbing oxygen and the other is Nd-rich phase condensing carbon. Carbon content were quantitatively confirmed by WDS analysis for the first time. The enrichment of carbon into Nd-rich phases were accelerated by a heat treatment in the temperature range between 500 and 800 °C. Coercive forces have significantly decreased at the content more than 0.1 wt. % of carbon.<ks>

Report by the Analytical Methods Committee. Evaluation of analytical instrumentation. Part VII. Simultaneous wavelength dispersive X-ray spectrometers

Report by the Analytical Methods Committee. Evaluation of analytical instrumentation. Part VII. Simultaneous wavelength dispersive X-ray spectrometers

Low-Energy Electron Induced X-Ray Spectroscopy (LEEIXS), An Emerging Technique in Surface and Thin-Film Analysis. New Developments and Applications

Within the last two decades analysis and characterization of surfaces, interfaces and very thin films have become of considerable importance in many fields of modern technology. This increasing demand has lead to a rapid development of various surface and near-surface analytical techniques. Some of these methods such as XPS, AES, SIMS and ISS have matured both with respect to instrumentation and methodology and therefore are now sufficiently well-established. Others are yet in their infancy but possess a large potential and this is the case of low-energy electron induced x-ray spectrometry (LEEIXS) discussed hereafter.The instrument is a wavelength-dispersive x-ray spectrometer in which the conventional x-ray tube has been replaced by an electronically stabilized gas-discharge source. Such a system operates as an electron source under the primary vacuum of the spectrometer (≃ 10−1 torr). Typical operating conditions are in the range 0.5-5 kV with a current of 0.1-0.5 mA and the diameter of the electron beam at the sample surface is less than 1 cm2.

Report by the Analytical Methods Committee. Evaluation of analytical instrumentation. Part VI. Wavelength dispersive X-ray spectrometers

Report by the Analytical Methods Committee. Evaluation of analytical instrumentation. Part VI. Wavelength dispersive X-ray spectrometers

Direct determination of zinc, lead, iron and total sulphur in zinc ore concentrates by X-ray fluorescence spectrometry

A direct X-ray fluorescence (XRF) method has been developed for the rapid determination of zinc, lead, iron and total sulphur present in zinc ore concentrates. The concentrations of the elements present, mainly as sphalerite, galena, pyrite and pyrrhotite, vary widely: Zn, 40–65; Pb, 0.1–10; Fe, 0.5–11; and S, 25–33%m/m. Using a wavelength-dispersive X-ray spectrometer and samples prepared as briquettes, Zn and Pb may be determined directly using the Kβ and Lγ1 lines, respectively. For Zn, a mathematical model (concentration-based correction equation) was applied to correct for inter-element effects. For the determination of Fe the ratio of the fluorescence intensities of the Fe Kα and Zn Kβ lines was used and, for the determination of total S, the intensity of the S Kα line was corrected with the Rayleigh scatter tube line, Rh Lα. For both iron and total sulphur, subsequent application of the mathematical model helped to correct for the residual inter-element effects. Good agreement was obtained between experimental and certified values for two international reference materials.

Characterization of microcrystallinity in hydrogenated silicon thin films

Lawrence Livermore National Laboratory (LLNL) and Sandia National Laboratories/California have jointly constructed a new nuclear microprobe beamline. This beamline is located on the LLNL 10 MV tandem accelerator and can be used for multidisciplinary research using PIXE, PIGE, energy loss tomography, or IBS techniques. Distinctive features of the beamline include incorporation of magnet power supplies into the accelerator control system, computer-controlled object and image slits, automated target positioning to sub-micron resolution, and video optics for beam positioning and observation. Mitigation of vibrations was accomplished with vibration isolators and a rigid beamline design while integral beamline shielding was used to shield from stray magnetic fields. Available detectors include a wavelength dispersive X-ray spectrometer, a High-Purity Germanium detector (HPGe), a Lithium-Drifted Silicon X-Ray detector (SiLi), and solid state surface barrier detectors. Along with beamline performance, results from recent measurements on determination of trace impurities in an International Thermonuclear Experimental Reactor (ITER) super conducting wire strand, determination of Ca/Sr ratios in seashells, and determination of minor and trace element concentrations in sperm cells are presented.

Diffusible sodium, potassium, magnesium, calcium and phosphorus in frog skeletal muscle.

A microvolumetric analytical method has been developed to measure the endogenous concentrations of diffusible elements in muscle cells. Single twitch fibres from frog muscle were skinned under oil and 0.2 nl drops of isosmotic sucrose solution, held in the tips of specially constructed pipettes, were placed in contact with the skinned fibres. After 0-10 min, the microdrops were removed and analysed with a wave-length dispersive X-ray spectrometer. The uptake of Na, K, Mg, and P into the microdrops was well fitted by a single exponential function, while the uptake of Ca was better represented by the sum of two exponential functions. All elements analysed except Ca reached diffusional equilibrium within 5 min of placing the microdrop on the fibre, while Ca was still not equilibrated at 10 min. For freshly isolated muscle fibres, diffusible element concentrations in the microdrops at equilibrium were (in mM, mean +/- S.D.): Na, 7.6 +/- 7.2; K, 82 +/- 36; Mg, 5.8 +/- 3.0; P, 51 +/- 19. Diffusible Ca concentration (at 10 min elapsed sampling time) was 0.7 +/- 0.4 mM. Results from experiments in which microdrops were equilibrated with skinned fibres pre-soaked in an artificial (Ca-free) solution support the notion that the exogenous solutes can replace the endogenous diffusible contents of a skinned fibre by soaking the skinned fibre in a relatively large volume of the artificial solution. Total Na, K, Mg, Ca, and P content of whole muscle was measured by electron probe analysis of muscle extracts. In freshly isolated muscle, whole muscle element content was (in mmol/kg wet weight, mean +/- S.D.): Na, 21 +/- 8; K, 120 +/- 26; Mg, 9.7 +/- 2.6; Ca, 2.2 +/- 0.5; P, 76 +/- 18. Extracellular fluid volumes of freshly isolated whole muscles were estimated by compartmental analysis of Na efflux. Extracellular element concentrations were measured by electron probe analysis of frog plasma. Using the extracellular fluid volume and concentration estimates, extracellular contributions were subtracted from measurements of the element content of whole muscle to yield estimates of total intracellular element concentration (in mmol/l myoplasmic water). Based on the values for the intracellular total and diffusible element concentrations, the diffusible/total content fraction in freshly isolated muscle is estimated to be: Na, 0.38; K, 0.48; Mg, 0.42; Ca, 0.22; and P, 0.47.

The Fabrication of Mercuric Iodide Detectors for Use in Wavelength Dispersive X-Ray Analysers and Backscatter Photon Measurements

ABSTRACTThis paper describes the fabrication of mercuric iodide nuclear radiation detectors suitable for X and gamma ray spectrometry at room temperature. The active area of the detectors studied are between 0.2 and 1.5cm sq and they are up to 0.5mm thick. The method of producing a stable electrical contact to the crystal using sputtered germanium has been studied. The X-ray resolution of a 1.5cm sq. area detector at 32 keV is 2.3 keV FWHM when operated at room temperature in conjunction with a time variant filter amplifier. A factor which is important in the fabrication of the detector is the surface passivation necessary to achieve a useful detector life.This type of detector has been used on a wavelength dispersive X-ray spectrometer for energy measurements between 10 and 100 keV. The advantages over the scintillation counter, more commonly used, is the improved resolution of the HgI2 detector and its smaller size. The analyser is primarily used for the detection of low levels of heavy metals on particulate filters. The detectors have also been used on an experimental basis for gamma ray backscatter measurements in the medical field.

Mitochondrial matrix granules in soft tissues: I. Elemental composition by X-ray microanalysis

The elemental composition of individual matrix granules in mitochondria of rat brown fat, mouse gall bladder and guinea pig kidney has been examined by X-ray microanalysis. The matrix granules showed a similar elemental composition that was strongly dependent upon the method of sample preparation. Low-temperature oxygen plasma microincineration or wavelength-dispersive X-ray spectrometers were used to demonstrate the presence of phosphorus in matrix granules of osmium tetroxide-fixed specimens. Matrix granule osmiophilia was retained in glutaraldehyde-fixed brown fat only if exposure to polar organic solvents was avoided during subsequent steps, e.g. by cryosectioning. As normally prepared, matrix granules lack detectable calcium but had bound this at detectable levels after fixation in osmium tetroxide, but not glutaraldehyde, supplemented with 5 mM Ca 2+. The results demonstrate that mitochondrial matrix granules of normal soft tissues are not calcium phosphate deposits and contain phospholipids, apparently as a major constituent. Thus they provide evidence against the hypothesis that matrix granules are primarily involved in mitochondrial calcium sequestration and, indirectly, for the hypothesis that the granules may be related to inner membrane assembly.

Analytical utility of the M series x-ray emission lines applied to uranium, neptunium, plutonium, and americium

Secondary emission x-ray analysis for actinide elements has usually meant utilizing the L series x-ray lines. The major disadvantage of these x-ray lines is that they fall in the region of high level Bremsstrahlung radiation, producing a high background and, subsequently, larger error and high detection limits. The utilization of the M series x-ray lines of actinide elements with wavelength dispersive x-ray spectrometers greatly minimizes these problems. Calibration curves for uranium, neptunium, plutonium, and americium were prepared by the ''coprex'' method, and the analytical characteristics of the L and M series compared. The M$alpha$ and $beta$ x-ray lines, under optimum conditions, are several times more sensitive than their L series counterparts. With the greater sensitivity in addition to the lower background, peak to background ratios for M lines up to 40 times greater than those for L lines were obtained. Detection limits can be lowered from about 0.7 $mu$g using the L$alpha$$sub 1$ line to 0.05 $mu$g when M x-ray lines are used. The relative advantages and disadvantages of utilizing the L and M series x-ray lines for secondary emission x-ray analysis are discussed. (auth)