bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy‐dispersive x‐ray fluorescence analysis in ecology: Problems and decisions
Authors: Margolyn E. M. , Ashkenazy S. I. , Fedoseev I. A. , Shilnykov A. M. 
Published: May 2005

AbstractThe basis of a universal software approach to assist in decisions related to those ecological problems appropriate for investigation by energy‐dispersive x‐ray fluorescence analysis is described. This concept is based on the use of the fundamental physical parameters of the interaction of radiation with materials; it uses modern mathematical methods, can be applied to many different ecological problems and is usable for a wide variety of x‐ray equipment.
Determination of trace elements in organic specimens by energy‐dispersive x‐ray fluorescence using a fundamental parameters method
Authors: Alvarez M. , Mazo‐Gray V. 
Published: May 2005

AbstractA rapid method for the simultaneous determination of trace elements in milk powder by energy‐dispersive x‐ray fluorescence has been developed. The measurement system consists of an Si(Li) detector, an x‐ray tube coupled with zirconium as a secondary target excited source and a personal computer. Milk powder was analysed as pressed pellets and irradiated for 1000 s. Concentrations were determined by a fundamental parameters method. The detection limits are close to 1 ppm for most of the trace elements. The accuracy of the method was ascertained by analysing standard reference materials from the International Atomic Energy Agency. Good agreement was found between the certified and experimental values. Potential areas of applicability of the method are indicated.
Addition of M‐ and L‐series lines to NIST algorithm for calculation of x‐ray tube output spectral distributions
Authors: Pella P. A. , Feng L. , Small J. A. 
Published: May 2005

AbstractAddition of M‐ and some minor L‐series characteristic lines to an analytical algorithm for calculation of x‐ray tube output spectral distributions is described. Such lines may be important for the analysis of elements of low atomic number (Z) where thin‐window, high‐Z target tubes are used for excitation.
Anomalies in the electron probe microanalysis of Y3Al5O12 garnets (YAG): An illustration of the role of beam‐induced field in insulator investigations
Authors: Fialin Michel 
Published: May 2005

AbstractThe difficulties that have been encountered in the electron probe microanalysis of Y3Al3O12 garnet (YAG) insulator (bandgap width = 7 eV) are discussed. Although alumina (Al2O3), whose bandgap width is closed to 10 eV, should be a suitable standard for Al measurements, the experimental results are affected by large errors. Pure Al used as a standard provides very accurate results. Such a strange behaviour can be understood by assuming that a strong increase in the electrical conductivity of YAG occurs under irradiation. This hypothesis is corroborated by the occurrence of electrical breakdowns under certain beam conditions. The presence of an electric field within Al2O3 can be revealed by the evolution of the Al Kα signal with irradiation time at low accelerating voltage (5 ke V). This evolution corresponds to a decrease in the internal field strength with a thermally induced increase in the electrical conductivity of the insulator.
Wavelength dispersion in one‐crystal and two‐crystal x‐ray spectrometry. A general treatment
Authors: Mathieson A. McL. 
Published: May 2005

AbstractThe representation in Δω, Δ2θ space of the components of diffraction associated with a single‐crystal reflection is proposed as an alternative to the DuMond diagram. The capabilities of this representation in relation to one‐ and two‐crystal spectrometry are discussed. It is shown that these two types of system have close similarity and can be integrated within a general treatment using Δω, Δ2θ space.
Current work on total reflection x‐ray fluorescence spectrometry at the GKSS research centre
Authors: Schwenke H. , Knoth J. , Weisbrod U. 
Published: May 2005

AbstractTotal reflection x‐ray fluorescence spectrometry (TXRF) was initially developed in order to enhance the detection performance in energy‐dispersive XRF using appropriate surfaces as sample carriers in the total reflection mode. The extension of this method to the analysis of surfaces required additional considerations together with refined instrumental design. As a secondary effect, the detection limits for trace analysis have been reduced by a further order of magnitude. In addition, new software has been developed. Special quantification procedures for surface analysis became necessary because of the complex behaviour of the primary intensity in near‐surface layers. The intensities are calculated on the basis of the Fresnel equations. Examples are given for the determination of thickness, elemental composition and density of surface layers in the nanometre range.
Some applications of the fundamental parameter method in energy‐dispersive x‐ray fluorescence analysis by isotope excitation
Authors: Szalóki I. 
Published: May 2005

AbstractThree iteration processes were developed for the quantitative determination of elements in solid samples. The methods used are based on a model expressing the relationship between the concentration and the characteristic intensity. The methods were checked by the analysis of steels, aluminium alloys, metallic glasses and organic samples.
SHAPE: A computer simulation of energy‐dispersive x‐ray spectra
Authors: Fernández J. E. , Sumini M. 
Published: May 2005

AbstractThe energy‐dispersive x‐ray spectrum is composed of a number of discrete XRF lines overlapping with a background which is due to processes of multiple scattering; both are modulated by the complex response function of the detector. Several physical processes contribute to the emission of x‐rays. Under the isolated atoms assumption, the main interactions to be considered are the Rayleigh and Compton scattering and the photoelectric effect. All of these processes taken independently produce well defined and theoretically valuable contributions. Recently, the most important of the multiple scattering contributions involving these interactions have been established analytically in the framework of the transport theory. The two kinds of contributions together give a more detailed physical picture of an x‐ray spectrom and make possible a closer comparison with experimental data. The SHAPE code uses this theoretical basis to simulate a complex x‐ray spectrum, giving the capability of making a complete characterization of every contribution. The theoretical spectrum may be optionally processed by a routine that simulates the response function of a solid‐state detector to produce a multi‐channel‐like output. Moreover, a graphic interface has been built in the program to allow the identification of the relative importances of the different processes and multiple scattering in every part of the spectrum with direct reading.
Monte Carlo simulation of the matrix and geometrical effects in x‐ray microfluorescence analysis of individual particles
Authors: Lankosz Marek 
Published: May 2005

AbstractA Monte‐Carlo model was developed for the simulation of x‐ray fluorescence (XRF) from spherical micro‐samples including primary and secondary fluorescence events. The interelement and geometrical effects in XRF microanalysis of individual mineral grains were studied. Calculations were performed for grains of Fe2O3 containing minor concentration of Ti and for ZnS grains. The results of calculation indicated that the intensities of excited characteristic x‐rays depend strongly on the diameter of the irradiated particle, the incident microbeam profile and its diameter.
Measurement of intensities of some newly observed diagram lines in the L‐emission spectra of 57La to 63Eu
Authors: Shrivastava B. D. , Gupta G. D. , Joshi S. K. 
Published: May 2005

AbstractA method is described for the estimation of relative intensities of weak diagram lines from the microphotometer records of x‐ray emission spectra registered on photographic films. The method is based on first correlating the experimentally determined relative intensities of two intense diagram lines with the theoretically calculated relative intensities. The experimental relative intensities of weak diagram lines are then interpolated to yield the corrected experimental relative intensities. These interpolated experimental relative intensities are found to be in good agreement with the theoretical relative intensities. The method has been applied to some recently reported weak lines in the L‐emission spectra of the rare earth 57La to 63Eu.
Measurement of the spectral distribution of a diffraction x‐ray tube with a solid‐state detector
Authors: Görgl R. , Wobrauschek P. , Kregsamer P. , Streli Ch. 
Published: May 2005

AbstractA knowledge of the spectral distribution method emitted by an x‐ray tube is important for all calculations in quantitative x‐ray fluorescence analysis. A simple way of directly measuring the primary spectrum of an x‐ray tube with a solid‐state detector is presented. For samples which meet thin‐film criteria sensitivity factors based on the measured primary spectrum were calculated and compared with experimental values.
Rayleigh and compton scattering contributions to x‐ray fluorescence intensity
Authors: Fernández J. E. 
Published: May 2005

AbstractThe enhancement of XRF intensity due to Rayleigh and Compton scattering in the target (which may occur after or before the photoelectric interaction) is commonly neglected in XRF spectrometry. However, this contribution can modify the XRF intensities to an appreciable extent, becoming a source of uncertainty for the computational methods of quantitative analysis. Analytical expressions are presented to describe the intensities of the corresponding four double interactions (which mix the photoelectric effect with the dominant types of scattering) that enhance the XRF intensity: Rayleigh‐photoelectric, Compton‐photoelectric, photoelectric‐Rayleigh and photoelectric‐Compton. These relationships are obtained by using an iterative solution of the Boltzmann transport equation for photons, suitable for the study of multiple scattering processes. It is shown that the first three chains contribute with discrete enhancements of the same energy of the XRF line. The last, in contrast, contributes with a short‐range continuous spectrum that overlaps the low‐energy tail of the peaks. This contribution can modify the line shape in a non‐symmetric way, making the unfolding of peaks from energy‐dispersive spectra more imprecise.The corrective terms to the XRF intensity are computed for both pure and composite materials. A common property to all of them is their azimuthal symmetry, a consequence of the isotropic behaviour of the photoelectric effect. As a rule, the chains with Rayleigh scattering predominate in the low‐energy regime and contribute between 1 and 10% of the primary XRF line. The chains with Compton scattering prevail at higher energy and their extent may exceed several tens percent. All the corrections show a broad range of variation depending on the incident energy, the composition of the target, which defines its attenuation properties for all the energies, and the incidence and take‐off angles.
Compton peak shift in XRF study of graphite
Authors: Kundra K. D. 
Published: May 2005

AbstractA significant shift from the theoretical position of the Compton peak was observed in a graphite sample using Rh Kα radiation. The magnitude of the Rh KαCompton peak shift depends on both the thickness of the graphite sample and the x‐ray beam diaphragm used. The larger the specimen thickness or the beam diaphragm size, the greater is the magnitude of the Compton peak shift. This Compton peak shift is interpreted as being due to the change in the ‘effective’ scattering angle, and it occurs with very light elements only.
Molybdenum concentration profiles in alumina cylinders by means of electron‐probe microanalysis
Authors: Vázquez P. G. , Riveros J. A. 
Published: May 2005

AbstractConcentration profiles for MoO3 were obtained from porous samples (supported catalysts). For this purpose, a technique for sample preparation and measurement was developed. Intensities were corrected by means of an updated multiple choice program, and good performance was obtained. The results show that the developed technique may be used upon any similar system.
Identification of the lines in the L emission spectrum of cerium and samarium
Authors: Shrivastava B. D. , Singh Devendra , Shrivastava Bhakt Darshan 
Published: May 2005

AbstractThe occurrence of a line at 2.1556 Å in the L emission spectrum of cerium and two lines at 1.6679 and 1.8379 Å in the L emission spectrum of samarium, reported many years ago, has remained a puzzle. These have now been identified as EXAFS minima occurring at the L absorption edges of the respective elements.
Lorentzian contributions to x‐ray lineshapes in Si(Li) spectroscopy
Authors: Campbell J. L. , Wang J.‐X. 
Published: May 2005

AbstractIf the lineshape response of a Si(Li) detector is measured using monoenergetic x‐rays provided by a monochromator, it must be convoluted by a Lorentzian of appropriate width in order to represent the lineshape encountered in directly measured x‐ray spectra. It is shown that the Lorentzian component is responsible for a significant fraction of low‐energy peak tailing, a phenomenon usually attributed to detector imperfections.
Kβ/Kα ratios and chemical effects in partially filled 3d‐shell elements
Authors: Raghavaiah C. V. , Rao N. Venkateswara , Sree Murty G. Krishna , Rao M. V. S. Chandrasekhar , Reddy S. Bhuloka , Sastry D. L. 
Published: May 2005

AbstractThe dependence of the Kβ/Kα ratio on the chemical constitution of the x‐ray emitting atom of 3d‐shell elements. V, Cr, Mn and Fe, was studied employing a high‐resolution Si(Li) detector. A maximum deviation of 9% in the Kβ/Kα ratio for the elements V and Mn is found when compared with their respective compounds. The experimental results are found to be consistent with the theoretical values due to Brunner's model.
X‐ray attenuation coefficients at 6.46 keV and the validity of the mixture rule for compounds
Authors: Kerur B. R. , Thontadarya S. R. , Hanumaiah B. 
Published: May 2005

AbstractX‐ray mass attentuation coefficients for the elements aluminium, copper, molybdenum and tantalum, the materials nylon, PTFE and lucite and the compounds magnesium sulphate, calcium sulphate chromium(III) acetate, cobalt acetate and zinc sulphate were measured using 6.46 keV photons from a 57Co source and adopting a novel method employing a proportional counter spectrometer. For the elements and materials the close agreement of the measured μ/ρ values with the theoretical values indicates the suitability of the proposed method for studying the validity of the mixture rule in the case of compounds. For magnesium sulphate, calcium sulphate, cobalt acetate and zinc sulphate the measured μ/ρ values agree within 1% with the theoretically estimated values, indicating the validity of the mixture rule. However, with chromium(III) acetate, where the chromium K‐edge is less than the incident photon energy by only about 471 eV, the measured μ/ρ value shows a deviation of about – 11%. This is attributed to the effects of EXAFS and to the effects of the chemical environment on the μ/ρ value, which result in an uncertainty in the value of μ/ρ to be used when applying the mixture rule.
Simplified mathematical approach to XRF secondary excitation
Authors: Bui C. , Milazzo M. , Sironi C. 
Published: May 2005

AbstractA secondary effect simplified mathematical expression (SESME) was developed to calculate, in a very simple way, the XRF enhancement effect by secondary excitation. This approximate methods makes possible the use of a simple algorithm in the case of a finite thickness sample also. The numerical approximations are quantitatively estimated for samples of infinite thickness and the physical meaning of the formal expression is discussed.
Experimental verification of a Monte Carlo method for x‐ray microfluorescence analysis of small particles
Authors: Lankosz M. , Holynska B. , Pella P. A. 
Published: May 2005

AbstractA Monte Carlo method for the simulation of matrix and particle size effects in the x‐ray microfluorescence analysis of individual particles was tested experimentally. Two procedures for experimental measurement of calcium and iron K x‐rays from spherical glass particles were developed and evaluated. The results of Monte Carlo simulation are in agreement with experimental data within 10% relative, and are considered satisfactory as a first step in performing quantitative microfluorescence analysis of particles having diameters less than 200 μm.
Determination of nearest neighbour distances of some nickel systems from XANES
Authors: Singh V. K. , Chetal A. R. 
Published: May 2005

AbstractXANES of the nickel systems NiO, LaNiO3, Ni(NO3)2 · 6H2O, NiSO4 · 6H20, NICO3 and Ni3(PO4)2 · xH2O were studied using a previously published equation and the nearest neighbour distances were determined and compared with the crystallographic values. The nearest neighbour distance of the system LaNiO3, whose crystallographic value is not available was also determined.
Sample transparency effects in tin determination by x‐ray fluorescence
Authors: Couture Rex A. 
Published: May 2005

AbstractA method is presented for the accurate trace determination of tin by wavelength‐dispersive x‐ray fluorescence with a rhodium tube. Because Sn Kα radiation and the incident radiation are very penetrating, sample transparency corrections and special background corrections are required. Explicit equations are derived for transparency corrections with polychromatic incident radiation. The 1/r2 dependence of incident intensity strongly affects the corrections. Using a simple, semi‐empirical correction procedure, and synthetic standards ranging from Al2O3 to Fe2O3, a calibration graph had a standard error of the estimate of only 1.8%. The detection limit is typically 3.5–4 ppm.
Problems of automated qualitative x‐ray fluorescence analysis 3—element selection
Authors: Jordanov Ju. , Tsanov Ts. , Stefanov R. , Yordanov N. , Ortner H. , Wilhartitz P. , Jenul R. 
Published: May 2005

AbstractA program for the automatic selection of elements found in the spectrum of a sample of unknown composition was developed. Coefficients of presence for elements were determined on the basis of some preliminary assumptions. A practical example is given.
X‐ray fluorescence line intensity expressions for the real divergence beam of an x‐ray tube
Authors: Verkhovodov P. A. 
Published: May 2005

AbstractA model for fluorescence radiation line intensity calculations with consideration of x‐ray tube primary beam radiation divergence and actual sample bulk, from which fluorescence radiation is registered at the detector, is proposed. Expressions are provided for commercial instruments having extended and circular sources. These expressions are valid for the short‐wavelength region of the spectrum and for substantial beam divergence, while the commonly used equations are invalid.
Sampling and sample preparation in EDXRS
Authors: Hołyńska Barbara 
Published: May 2005

AbstractThe principles of sampling, sample storage and sample preparation prior to energy‐dispersive x‐ray spectrometry with special attention paid to the methods of obtaining representative samples of heterogeneous materials such as soil, biological and geological specimens are presented. Problems occur with losses of elements to be determined and also contamination of the sample. Sample preparation prior to analysis of environmental, biological and geological materials with and without chemical pretreatment is discussed. The procedure of sample digestion followed by preconcentration and separation of the elements to be determined is discussed. Reference materials are needed for testing the applied procedures.
Calculation of the enhancement of characteristic radiation due to scattering in radioisotope XRF using exact differential cross‐sections
Authors: Karydas A. G. , Paradellis T. 
Published: May 2005

AbstractThe scattering of either the exciting or the characteristic radiation enhances and reduces the XRF intensity. The resultant enhancement has been calculated using exact differential scattering cross‐sections and employing an arithmetic integration. By using radioactive sources the scattering corrections for some thick pure targets were determined experimentally.
Elemental mapping of bone tissues by the use of capillary focused XRF
Authors: Voglis P. , Attaelmanan A. , Engström P. , Larsson S. , Rindby A. , Boström K. , Helander C. G. 
Published: May 2005

AbstractA description of the x‐ray microbeam spectrometer at Chalmers University of Technology is given with particular emphasis on the mapping and imaging features. The application of the microbeam technique to the analysis of bone specimens is also described.
Sample preparation and EDXRF analysis of element content in marine algal communities — a tentative approach
Authors: Boman J. , Blanck H. , Standzenieks P. , Pettersson R. P. , Hong N. T. 
Published: May 2005

AbstractThe relative distribution and retention of elements in algal communities can potentially be used as an ecologically relevant effect parameter in ecotoxicological studies. Energy‐dispersive x‐ray fluorescence spectrometry (EDXRF) was used for multi‐element analysis of samples of marine algae and plankton. The algal samples were microbial periphyton communities, attached to glass substrata that were submerged in marine waters at the Swedish west coast. The phytoplankton samples from the same area were taken in a polyethylene bottle and collected on polycarbonate filters. The EDXRF spectrometer used is based on three‐axial geometry. This geometry together with optimized collimation of the x‐ray beams results in a low background well suited for the analysis of the small biological samples in this study. The aim of this study was to investigate sample preparation procedures suitable for EDXRF analysis of algal communities. A rapid wash in distilled water, to remove the interfering interstitial sea water, and subsequent transfer of the community to an x‐ray foil is the tentatively proposed sample preparation procedure.
Total reflection x‐ray fluorescence spectrometry of metal samples using synchrotron radiation at SSRL
Authors: Hegedüs F. , Wobrauschek P. , Sommer W. F. , Ryon R. W. , Streli Ch. , Winkler P. , Ferguson P. , Kregsamer P. , Rieder R. , Victoria M. , Horsewell A. 
Published: May 2005

AbstractIt was demonstrated that a total reflection x‐ray fluorescence spectrometer, using monoenergetic synchrotron radiation as the primary x‐ray source, is suitable to measure the concentration of transmutational elements in Cu and Fe metal matrices. In a typical irradiation of copper with 590 MeV protons or with spallation neutrons, where the damage dose is 0.4 dpa (displacement per atom), the calculated concentration of transmutational elements is Ni 25, Co 8 and Fe 8 μg g−1. The results show that the minimum detectable concentrations were lower than these values. The energy of the sychrotron radiation was set just below the K‐edge energy of the matrix element, eliminating the large peak due to the matrix. As an example, in the case of a Cu (Z = 29) matrix, the minimum detectable concentration for Ni (Z = 28) was as low as 3 μg g−1. In order to check systematically the possible geometric arrangements of beam direction–reflector position–detector position, a new vacuum chamber was designed and tested. It provides all technical components for remote control of the adjustment procedure to align the reflector in total reflection geometry. Two ways of positioning the reflector in the beam, vertical to the plane of polarization and parallel to that plane, were investigated, to find the best excitation conditions and lowest limits of detection. A few pg corresponding to a concentration of ng g−1 of samples where the matrix can be easily removed as in aqueous or acidic solutions and 50 ng g−1 concentration of metals in a light matrix as in oil were found as detection limits.