Use Of X-ray Fluorescence Research Articles

Coatings Technology Handbook, Second Edition

Coatings Technology Handbook, Second Edition

Selective removal of some heavy metal ions from aqueous solution using treated polyethylene-g-styrene/maleic anhydride membranes

Radiation graft copolymerization of styrene/maleic anhydride (Sty/MAn) comonomer onto low density polyethylene (LDPE) membrane was investigated. The prepared grafted membranes were treated with different reagents containing various functional groups and studied as a matrix for the purpose of water purification from heavy metals. The metal ion uptake by the functional groups of membranes was determined by the use of X-ray fluorescence (XRF) and atomic absorption (AA). The effect of pH of the metal feed solution and immersion period needed for maximum capacity was investigated. The selectivity of different prepared membranes towards some selected metal ions such as Fe, Cu, Pb,… etc. which commonly exist in waste water was determined. The affinity of the treated grafted films to recover Fe(III), Cu(II) or Pb(II) from their aqueous solutions containing other metal ions such as Cd(II), Ni(II) or Hg(II) was studied. Also the selectivity of treated grafted membranes towards Cu(II), Cr(III) and Fe(III) in a mixture was investigated at room temperature and 70°C. It was found that the thiosemicarbazide-, hydroxylamine·HCl- and NaOH-treated grafted films showed high selectivity towards Cu(II), Cr(III) and Fe(III), respectively, at 70°C. However, the selectivity of such treated grafted membranes was remarkable towards Fe(III) at room temperature. The results obtained suggested that the treated grafted membrane possessed good chelating properties towards different metal ions. This suggests that such membranes could be accepted for practical uses.

A cone penetrometer X-ray fluorescence tool for the analysis of subsurface heavy metal contamination

Past use of X-ray fluorescence for the analysis of heavy metal contamination in soil was limited to analyzing either collected samples or soil on an exposed surface. To investigate subsurface contamination at even shallow depths, extensive and often expensive drilling or excavation was required to obtain either a sample or an exposed surface. A cone penetrometer X-ray fluorescence tool has been developed by the US Army, Navy and Air Force Site Characterization and Analysis Penetrometer System (SCAPS) to analyze subsurface metal contamination in situ. Using this tool, subsurface metal contamination can be investigated in real time without sampling or excavation. A schematic diagram of the penetrometer tool is provided and operating capabilities are discussed. The results of bench testing and a calibration for lead contaminated standards are presented.

X-Ray Microscopy Developments at the ESRF

Abstract The ESRF source properties offer the required coherence and brilliance to extend X-ray microscopy techniques, which have been extensively used in the soft X-ray region, to higher energies. This will enable new investigations such as the study of thicker specimens compared to the soft X-ray region, access to absorption edges of elements of major interest in the biological and materials sciences, in particular from Potassium to Chromium, the use of X-ray fluorescence for trace element mapping with high spatial resolution and the application of phase contrast. Two microscopes are under development at the ESRF to cover a wide range of biological and material sciences applications: A scanning transmission X-ray microscope (STXM) working in the photon energy range of 0.5-8keV. Whilst in its simplest form this might consist of taking multiple images of a single sample region at different incident energies, an interesting extension is to perform highly spatially resolved XAS scans on small regions of the sample.

Analysis of rock phosphates by x-ray fluorescence spectrometry

Elemental composition of phosphate fertilizers is of interest because of the possible migration of elements from the fertilizers to soil and plants, and via the food chain, to human beings where this may result in health effects. Several methods have so far been used for the measurement of both toxic elements and radionuclide concentrations in phosphate fertilizers. In this work the use of x-ray fluorescence is described and elemental compositions of rock phosphate samples of different origin are presented.

X-Ray Fluorescence and Reflectivity Analysis of Multiple-Layer Thin Films

The use of X-ray fluorescence and reflectivity techniques for the characterization of the layer structures of multiple-layer thin films is described. The X-ray fluorescence technique is used for the precision determination of composition and layer thicknesses of two triple-layer NiFe, Cu, and Cr thin films. The X-ray reflectivity technique is used to determine the values of layer thickness, density, and roughness of a six-layer Ta/FeMn/NiFe/Cu/NiFe/Ta thin film. Both X-ray fluorescence and reflectivity techniques are used for the analysis of two Au/NiFe multilayers. The results showed that the X-ray fluorescence and reflectivity techniques are complimentary. The use of both techniques for layer-structure determinations improves the reliability of the analysis.

Uniformity of Arsenic Dimer and Tetramer Fluxes from a Valved Arsenic Cracking Source in MBE

AbstractWe have studied the uniformity of the arsenic flux from a commercially available valved arsenic cracker source for MBE. There are many epitaxial structures that require a uniform arsenic flux distribution for rotated epitaxial growth and, in the non-rotated case, for RHEED. For non-stoichiometric GaAs growth at low substrate temperatures, which results in arsenic precipitates being formed during the in-situ anneal process, a specific As/Ga ratio must be used to maintain high crystalline quality and to achieve the desired electrical properties. Also, in the growth of InGaAsP the As/P ratio is equally important for lattice match and quality device results. We report on the uniformity of amorphous arsenic (a-As) films condensed on the surface of 3" diameter sapphire wafers slightly below room temperature. Sapphire substrates were used in place of GaAs wafers to facilitate the use of x-ray fluorescence for the measurement of the arsenic film uniformity. Uniformity maps will be presented for rotated and non-rotated a-As depositions of As2 and As4. Results indicate the uniformity of a-As, As4, films to have a standard deviation of < 2.5% across a 3" diameter substrate for the rotated case. Characteristics of the non-rotated case will be presented.

The use of X-ray fluorescence to detect lead contamination of carpeted surfaces

The use of X-ray fluorescence to detect lead contamination of carpeted surfaces

The use of X-ray fluorescence to detect lead contamination of carpeted surfaces

The recognition of the hazards to young children of low-level lead intoxication and the widespread distribution of lead in the urban environment have resulted in massive federal, state, and local lead awareness and abatement programs. Two of the most significant exposure routes of lead to young children are the soils and dusts found within the child's home. Most state and federal lead abatement programs deal with lead-based paint contamination but often do not address the issue of soft-surface contamination, such as that of carpets, furniture, and draperies. Carpets can be a reservoir of contaminated soils and dusts; currently, there exists no standard method to test carpeted surfaces for lead contamination.This paper describes a study that uses X-ray fluorescence (XRF) to test carpeted surfaces for lead contamination. XRF technology is the standard technology used in lead-based paint testing and is known to be an accurate technique to test for lead in soils. This study uses a controlled laboratory atmosphere to evaluate this technology; the objectives are to determine: (1) a lower limit of detection for the instrument; and (2) whether soil loading levels can be differentiated by XRF using trace elements also present in the soil. Results indicate that XRF can easily differentiate soil loading levels (g soil/m(2) carpet). The lower limit of detection of soil lead concentration on the carpet is a function of both soil lead concentration and soil loading; therefore, lead loading (mg Pb/m(2)) is a better indicator of detection limit than soil lead concentration. Lead loading detection levels from 108-258 mg Pb/m(2) were obtained, as compared to a level of 10 000 mg/m(2) (1 mg/cm(2)) for lead on painted surfaces as required by theLead-Based Paint Poisoning Prevention Act.XRF technology has the potential to be a fast, inexpensive screening technique for the evaluation of lead contamination on carpeted surfaces.

THE SCIENTIFIC IDENTIFICATION OF ARCHAEOLOGICAL JET‐LIKE ARTEFACTS

Jet has been widely used in the past for jewellery but was just one of a range of black lithic materials employed. When worked into small objects these materials can be visually indistinguishable, yet discrimination is important because of the restricted occurrence of jet. X‐ray fluorescence (XRF) is a rapid non‐destructive discriminatory technique, but not all samples are clearly classified, and inhomogeneity may pose problems. A reassessment of the use of XRF is reported. Other techniques considered include electron spin resonance, infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy and X‐radiography. These were tested on geological materials to define an effective methodology for archaeological material. The recommended approach is a combination of XRF and X‐radiography, although preliminary Fourier transform infrared results showed promise. The X‐ray techniques were tested on Romano‐British assemblages from Catterick and Stanwick.

Composition, structure, and electrical properties of Bi2Sr2Ca1-yYyCu2O8: A single-crystal study.

A systematic study of yttrium substitution for calcium in the high-temperature superconductor ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ has been performed. Single crystals were grown, cleaved, and characterized with use of x-ray fluorescence, electron microprobe, and electron- and x-ray-diffraction techniques. The dc resistivity, diamagnetic shielding, and Hall coefficient of the samples were also measured as functions of the temperature from 4 to 300 K for different dopant concentrations. We conclude that our systematic substitution in the family ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{Ca}}_{1\mathrm{\ensuremath{-}}\mathit{y}}$${\mathrm{Y}}_{\mathit{y}}$${\mathrm{Cu}}_{2}$${\mathrm{O}}_{8}$ gives an insight into this high-temperature superconducting material as well as into weak localization and metal-insulator transitions.

Understanding Art Through Technical Analysis Inferences From Pigment Identification

ABSTRACTPigment identification and technical analysis of works of art provide the historian and conservator with information that allows a new view of an object. The methods the analyst chooses depends on the nature of the sample and the materials and method expected for the age of the object being examined. Several analytical methods are used frequently in the museum field with great success; these include x-ray fluorescence spectroscopy, x-ray powder diffraction methods and optical microscopy. Results from the analysis of pigments in paintings by Derain, Beckmann, El Greco, G. David, and Gentileschi are given. The results include discovery of an unpublished formulation of cobalt violet, example of the use of particle size to change the appearance of color, and the use of x-ray fluorescence to determine artists' palettes without removing samples from the works of art. The study of the El Greco and the Gentileschi show how technical investigations can complement art historical research.

ChemInform Abstract: EVALUATION OF THE PHOSPHORUS CONCENTRATION AND ITS EFFECT ON VISCOUS FLOW AND REFLOW IN PHOSPHOSILICATE GLASS

This study describes the use of x-ray fluorescence as an analytical tool for determining phosphorus concentration in phosphosilicate glass. By comparison with other available methods, we shall demonstrate that this direct measurement technique is accurate, simple, fast, reproducible, and nondestructive. With the use of this technique, flow and reflow profiles of phosphosilicate glass will be illustrated at different phosphorous concentrations and representative thermal cycles.

An X-Ray Fluorescence Coating Gauge for Paint Thickness

The industrial use of X-ray fluorescence (XRF) coating gauges is a well established practice. For homogeneous coatings such as zinc or tin on steel, on-line XRF gauges are in use around the world. In continuous coating lines coils of uncoated metal are welded to one another and are coated at speeds between 100 and 2000 ft/min. Gauges are used to read cross-sheet coating profiles and determine the average coating thickness through the length of the coil. The motivation for the use of these on-line X-ray instruments is quality control, particularly coating uniformity, and raw materials savings.

Use of X-ray fluorescence for chemical analysis

Major advances in X-ray fluorescence analysis during the last three years are reviewed. Considerable progress has been noted in the use of radioactive sources, small X-ray tubes and energy analysis by solid state detectors. Much of the review deals with published applications of X-ray fluorescence in chemical analysis. An attempt is made to forecast future developments and comparison with other analytical techniques suggests that X-ray fluorescence spectrometry will maintain, and possibly increase, its relative importance.

Analysis of French, English and Scottish Pewter Measureg Using Energy Dispersive X-ray Fluorescence Analysis

The use of X-ray fluorescence for the surface analysis of museum objects has been described by numerous authors. (1, 2, 3, 4) Some problems of the technique, such as the lack of homogeneity in alloys and the effects of surface configuration on quantitative results have been discussed. For quantitative analysis it is considered essential that all samples and standards in a given analysis be equivalent with respect to effective specimen area in shape, dimensions, orientation, inclination to the primary and secondary beams, distance from the X-ray tube and detector, and surface contour. The first two factors, size and shape of effective specimen area, can be handled by the choice of appropriate specimen masks or apertures. The other factors of inclination to the beams, distance from X-ray tube and detector, and surface configuration are extremely difficult to hold constant when analyzing non-flat objects, yet each affects the intensity of the beam reaching the detector. Failure to keep these factors constant from sample to sample will result in variations in intensity which are not related to composition.

The use of X-ray fluorescence in rapid in vivo measurements of iodine, gold and mercury

Efforts are being directed towards developing a rapid method of in vivo measurements of these elements, requiring simple and fast sample preparations. Several methods of exciting the material of interest have been investigated. 241Am is used as a direct source for irradiating the iodine in solution. The use of rare earths as secondary sources in conjunction with an X-ray tube is also being studied. Also the coincidence counting technique is being investigated. The X-ray fluorescence is measured on a KeVeX Si(Li) semiconductor detector.

Preparation, identification and crystal structure of SmAl

Abstract : Single crystals of the intermetallic phase SmAl were formed on an Al2O3 surface during an attempt to produce single crystals of samarium metal. This note describes the production of the SmAl crystals, the use of X-ray fluorescence and electron probe techniques to determine the chemical composition of the crystals, and the X-ray diffraction data obtained.

Iron Oxide Determination by X-Ray Fluorescence for In-Process Control of Solid Propellant and Premixes

AbstractFinely divided iron oxide is used as a burning-rate catalyst in several solid rocket propellants. The concentration is critical and must be accurately determined as a quality control point before the propeltant is cast in the motor case and cured, in addition to the iron oxide, the propellant used for ignition of the Air Force Minuteman first stage contains a polymeric binder system, a solid oxidizer, and a metal powder. This composition makes it difficult to determine accurately the iron content by wet methods in the time available daring the propellant processing cycle. The use of X-ray fluorescence has been investigated as a means of satisfying the analysis time requirements while meeting the prescribed accuracy of ±1% of the amount of iron oxide present. Procedures for preparing test specimens have been developed and instrument operation conditions chosen which yield satisfactory precision. When ten specimens from each of three premixes were analyzed for iron content, the observed within-mix mean relative standard deviation was 0.28%; for propellant analyzed under the same conditions, the mean relative standard deviation was 0.35%. Factors affecting mix-to-mix accuracy, such as particle size and shape and interelement absorption and enhancement effects, have been investigated. Accuracy is adequate for in-process control of the iron oxide level in the premix, but further work is required before satisfactory control of propellant is achieved.