bluuebunny/crossref_metadata_2025 huggingface dataset:
Limiting values of matrix effects in XRF analysis and some of its consequences
Authors: Kuczumow Andrzej , Szewczak Marek
Published: May 2005

This paper considers some limiting values of matrix effects on the basis of the version of the Shiraiwa and Fujino equation which takes into account matrix effects, expressed explicitly. It has been proved that one can obtain the limiting values of absorption and enhancement effects in those cases in which the concentration of the matrix element j tends to unity, and boundary values of absorption and self‐absorption effects in the case when photons of exciting x‐ray radiation have energies that considerably exceed the value of the absorption edge of the analysed element i. In addition, the limit of the enhancement effect at the point of the absorption edge of the matrix element j is given. A hypothesis is formulated concerning the linearity of the reciprocal of the enhancement function versus the concentration of the enhancing element j. This implies new important solutions of the Tertian equation, at least in the case of monochromatic excitation. The notion of effect equilibrium points and a search for them were also considered. Effect equilibrium points were registered as a consequence of concentration changes and also of changes in the exciting radiation energy.
Wavelength‐dispersive X‐ray fluorescence spectrometric technique for determining major and minor elements in columbite–tantalite using a rhodium excitation source
Authors: Tikoo B. N. , Viswanathan S.
Published: May 2005

A simple, accurate, precise and rapid technique is described for determining Nb, Ta, Fe, Mn, Ti, Sn, W, Zr, Y, U and Th in columbite–tantalite (CBTA) using undiluted, plain, pressed CBTA powder pellets of 41 mm diameter prepared from 1‐g powders. The intensities of the characteristic radiations measured are transformed to element concentrations using least‐squares regression equations derived from the corresponding intensities of, and oxide values in, chemically analysed natural CBTA standards (for Nb, Ta, Fe, Mn, Ti and U), hemi(semi)‐natural standards (that is, columbite–tantalite used as base for spiking spectrographically pure chemicals) for Sn, W and Y and synthetic standards for Zr. Owing to a lack of sufficient natural CBTA standards containing a wide range of thorium, the intensities of the radiation characteristic of thorium are converted to Th contents using the normal relationship between intensity and concentration involving mass absorption coefficients.

The relative accuracy of the proposed method is excellent (within 1.5%) for Nb, Fe and Sn, very good (within 3.5%) for Ta, Mn, W and U, good (within 6.5%) for Ti, Zr and Y and fair (within 10%) for Th. The precision is excellent (within 3%) for Nb, Ta, Fe, Mn, Ti, Sn, W, Zr, Y and U and very good (within 6%) for Th. The 11 elements in a batch of 24 samples with replication of four analyses per elment per sample can be determined by one operator in 9 days.
Quantitative X‐ray microanalysis of thin foils in STEM
Authors: Voice W. E. , Bradshaw T. J. , Faulkner R. G.
Published: May 2005

A method, denoted MCAF, is described for the correction of x‐ray intensities obtained during energy‐dispersive analysis of alloy thin foils. The procedure is based on a Monte Carlo simulation of electron trajectories which defines the x‐ray generation distribution, together with absorption and fluorescence corrections.

Results are presented for the analysis of three alloys: Nimonic C263, Type 304 stainless steel and a specifically cast and homogenised Ni–Al–Ti single‐crystal alloy. The results indicate that the correction procedure works well at various foil thicknesses and take‐off angles. The extent to which absorption of Mo in C263 and Al in the Ni–Al–Ti alloy and fluorescence in the stainless steel occurs is discussed. It is shown that fluorescence in thin foils, even of stainless steels, can be ignored below about 350 nm.

Some comparison is made between the results predicted by MCAF and those obtained with a commercially available, thin foil correction procedure, RTS2.
Detection limits of external beam PIXE in the analysis of thick samples for elements with Z ≥ 26
Authors: Räisänen J.
Published: May 2005

The limit of detection of the external beam PIXE method was investigated in the proton energy range 1.7–5.6 MeV for elements with Z ≥ 26. The effect of matrix composition was studied by evaluating detection limits for typical thick organic, biomedical, bone and geological samples. Particular attention was paid to the optimization of measuring times.
The self‐absorption correction in PIXE microanalysis
Authors: Dyson N. A. , Fakhouri Haifa
Published: May 2005

The self‐absorption effect for characteristic x‐rays produced by proton bombardment of thick targets has been studied experimentally by the ‘tracer‐layer’ and ‘angular distribution’ techniques. Four proton energies have been used. The experimental data have been converted into f(χ) curves which can be used to apply a self‐absorption correction in PIXE microanalysis.
Profile analysis of experimental x‐ray fluorescence spectra
Authors: Huang T. C. , Lim G.
Published: May 2005

A systematic study has been made of the line shapes of x‐ray fluorescence spectra obtained with a conventional spectrometer using various analysing crystals and experimental conditions. It was found that each component of the K and L spectra can be closely matched by the sum of an asymmetric Gaussian and Lorentzian, namely the pseudo‐Voigt function. Analysis of spectra in the 0.4–3 Å range showed that profile shapes are functions of 2θ, the analysing crystal and the collimating system, but nearly independent of chemical state, specimen thickness and operating voltage. For a fixed analysing crystal and collimator, larger values of 2θ exhibited lower Gaussian content and higher asymmetry. Using an LiF (200) crystal, spectra obtained for 2θ° < 20° were found to be pure Gaussian and symmetric, indicating the dominance of the instrumental effects. As 2θ increased, the Lorentzian component or the spectral effects emerged and the shapes became asymmetric. The analysing crystal has a pronounced effect on the experimental profile shapes. Use of a graphite (002) instead of an LiF (200) crystal yielded profiles three times wider and with twice the Lorentzian content. The differences between PET and LiF crystals were smaller. The accuracy achieved in using the pseudo. Voigt function to describe the experimental XRF spectra demonstrates the convenience and effectiveness of the function in obtaining precise fluorescence intensities, especially in the case of poor counting statistics and/or overlaps.
Cubic spline representation of the two‐variable cumulative distribution functions for coherent and incoherent x‐ray scattering
Authors: Yacout A. M. , Verghese K. , Gardner R. P.
Published: May 2005

In Monte Carlo simulation of energy‐dispersive x‐ray fluorescence analysers, one must account for both x‐ray scattering effects and photoelectric absorption. To access the required random values of differential coherent and incoherent scattering angles, two‐variable cubic spline representations of the appropriate cumulative distribution functions are developed and their use is demonstrated. In this approach the scattering angle is taken to be the dependent variable while the two independent variables are the x‐ray energy and the normalized cross‐sections.

Cubic spline coefficients for the elements from sodium to nickel have been obtained for x‐ray energies from 1 to 150 keV for all scattering angles for both coherent and incoherent scattering. Compared with the commonly used method of numerically integrating tabular values of coherent and incoherent cross‐sections to produce a table of values for subsequent interpolation, use of cubic spline representations gives a 90% reduction in storage space and a 25–80% reduction in the amount of computer time required for equal accuracy.
A modified theoretical model for the efficiency calculations of a Si(Li) detector
Authors: Garg M. L. , Singh Jasbir , Verma H. R. , Trehan P. N.
Published: May 2005

A radial efficiency correction factor was introduced in the five‐parameter radially dependent model by Cohen to calculate the theoretical efficiency of an Si(Li) detector. The present calculations for the various detectors confirm that the radial dependent factor introduced by Cohen is a geometry‐dependent factor and does not depend on the physical characteristics of the detector. The modified five‐parameter model suggested in this study removes the anomaly between the theoretical calculations and experimental observations.
Surface and near‐surface chemical characterization by low‐energy electron‐induced X‐ray spectrometry (LEEIXS): A review
Authors: Romand M. , Bador R. , Charbonnier M. , Gaillard F.
Published: May 2005

Various experiments show that low‐energy electron‐induced X‐ray spectrometry (LEEIXS), using a gas discharge tube as an efficient and stable electronic excitation source, represents a powerful new technique in many fields of research related to surface and near‐surface chemical characterization of materials. The instrument is a wavelength‐dispersive X‐ray spectrometer capable of high qualitative or quantitative performances in the soft and ultra‐soft region (λ = 0.3—10 nm). LEEIXS applications given in this paper demonstrate how chemical, electrochemical or physical treatments of various substrates modify the solid surface composition.
Excited fluorescence in low‐Z elements by the low‐energy gamma transitions and L X‐rays from a 241‐am XRF source
Authors: Delgado V. , González L. , López A. , Morán P. , Vañó E.
Published: May 2005

The influence of the photons emitted by a 241Am XRF excitation source below 59.6 keV on sample fluorescence production has been analysed. A general method for evaluating the contribution of the various lines from the source in specific equipment configurations is presented. The excitation was performed with 23 elemental targets and the measured experimental intensities were fitted by means of a minimization program which takes into account the most important transition groups observed in the spectrum of the excitation source. The program allows for attenuation of excitation and fluoresced photons in the target. Intensity data for the exciting beam were compared with the theoretical intensities of photons from 237Np, and it was concluded that these values are compatible with the Am and Al thicknesses of the excitation source. Correction factors considering low‐energy transitions were calculated for several elements for both thick and thin targets. The over‐excitation evaluated for Z = 34 reached values ranging between 180% and 550%.
Determination of metals in oil using total reflection X‐ray fluorescence spectrometry
Authors: Bilbrey D. B. , Leland D. J. , Leyden D. E. , Wobrauschek P. , Aiginger H.
Published: May 2005

Oil was chosen as a new sampl type for total reflection XRF. A thin‐film sample procedure is described which requires minimal sample preparation. This involves first bringing the oil into solution with a volatile solvent, then pipetting microliter amounts on to the reflector substrate followed by evaporation of the solvent. The linear dynamic range was found to extend to at least 5000 ppm. Detection limit measurements show that minute sample quantities are necessary for optimal detection limits of nanogram amounts. A maximum sample loading is required for the best detection limits in ppm. Using an Mo or Cu X‐ray tube, limits were found to be a few ppm or sub‐nanogram amounts. The spectrometer was calibrated by an internal standardization method and the results of determinations on sample solutions were typically within 10% relative accuracy.
Measurement of K X‐ray fluorescence cross‐sections for some elements with 23 ≤ Z ≤ 55 in the energy range 8–60 kev
Authors: Kumar Sudhir , Singh Surinder , Mehta Devinder , Singh Nirmal , Mangal P. C. , Trehan P. N.
Published: May 2005

Kα and Kβ X‐ray fluorescence cross‐sections were measured for V, Mn, Co, Br, Rb, Mo, In, Sb, I and Cs at nine excitation energies ranging from 8 to 60 keV using energy‐dispersive X‐ray fluorescence spectrometry. The results were in good agreement with the theoretical values calculated using photoionization cross‐sections based on the Hartree‐Fock‐Slater model.
Ice thickness and low‐energy Si(Li) detector efficiency measurements
Authors: Cohen David D.
Published: May 2005

A simple technique for measuring the thickness of ice build‐up on the front face of Si(Li) detectors is described. This ice thickness varies with time and significantly modifies the low‐energy efficiency of Si(Li) detectors in the 1–5 keV energy range. We also report on the branching ratios for the ten resolvable neptunium M shell X‐ray lines from thin 241Am α sources.
Problems of automatic qualitative X‐ray fluorescence analysis: Part one
Authors: Jordanov J. U. , Tsanov T. S. , Stefanov R. , Jordanov N.
Published: May 2005

The first three stages of the automatic qualitative X‐ray fluorescence analysis: scanning of the spectrum, smoothing of the spectrum and approximation of the background are described. Considerations about optimal smoothing of the spectrum are presented using the different features of analytical lines and noise. A function well approximating the background intensity in dependence on the wavelength is found, and a method for background construction from the minima in the spectrum is discussed.
Absolute method for determination of metallic film thickness by X‐ray fluorescence
Authors: Vázquez C. , de Leyt D. V. , Riveros J. A.
Published: May 2005

An absolute method for the determination of the thickness of a nickel film on iron has been developed. The mass absorption coefficient of nickel for the effective wavelength has been determined empirically and mathematically. The found values were in agreement. To perform this method only one intensity measurement of the fluorescent substrate emission is required (Fe Kα). The method was tested using iron sheets with different thicknesses of nickel obtained by chemical deposition. Thicknesses between 6 and 25 μm produced relative differences from gravimetric values of 1.8‐1.1%.
Sample preparation method for major‐element analyses of carbonate rocks by X‐ray spectrometry
Authors: King Bi‐Shia , Vivit Davison
Published: May 2005

A sample preparation method is described which permits fast and accurate wavelength‐dispersive, x‐ray fluorescence analysis of ten major oxides in carbonate rocks. The sample is first ground into a fine powder, then calcined, its loss‐on‐ignition (LOI) is determined and finally it is fused into a glass disc with lithium tetraborate at 1100°C using a 1:10 sample‐to‐flux ratio. Geological reference standards and synthetic standards are used for calibration. Matrix effects are corrected empirically using Lachance‐Traill correction algorithms. The accuracy and precision of the method were assessed by the analysis of several NBS carbonate reference standards.
Quantitative XRF analysis of surface layers: Influence of primary energy distribution and enhancement
Authors: Rössiger V.
Published: May 2005

A theoretical approach to quantitative x‐ray fluorescence analysis of multicomponent surface layers is described. It includes both the determination of the primary energy distribution of the tube and the calculation of the x‐ray intensities according to the fundamental parameter method. The effects of several inaccuracies, such as those from the primary distribution, from the treatment of secondary excitation and from the analytical representation of attenuation cross‐sections, are discussed in detail. Their influence on the XRF intensities was studied theoretically and compared with experimental data for a wide variety of well defined multilayer systems. The final accuracy of the theoretical calculations allows one to dispense with calibration reference standards in practical analytical work.
Loss‐on‐ignition corrections in the XRF analysis of silicate rocks
Authors: King Bi‐Shia , Vivit Davison
Published: May 2005

An empirical method for loss‐on‐ignition (LOI) corrections in XRF analysis is presented. It is based on a polynomial relationship between the disc weight ratio (D/Dz) and the analyte concentration ratio (Ciz/Ci) for a series of synthetic standards with various known LOI contents, where Dz and Ciz are disc weight and analyte concentration, respectively, at zero LOI. The coefficients derived from regression analysis of the relationships are unique to each analyte element, and may be used to adjust the disc weight ratio. The adjust disc weight ratios are than applied to correct the apparent concentration to a standard measurement condition, which is zero LOI

The effectiveness of this LOI correction method was verified experimentally by the analysis of some well characterized geochemical reference samples with various LOI contents and the results were found to be in good agreement with the recommended values.
Precise calibration of sequential x‐ray spectrometers
Authors: Sperling Z.
Published: May 2005

Small differences between actual 2d spacings of analytical crystals and those used for the calculation of 2θ tables generate θ‐dependent deviations of measured 2θ values from tabulated values of up to several tenths of a degree. It is shown that these deviations can be separated into a constant and a tan θ‐proportional component and used for a precise calibration of the spectrometer in terms of the actual value of the 2d spacing of the analytical crystal and of the 2θ dial offset. The reported results were obtained on two instruments, an older manual spectrometer and a newer one operating under computer control.
Enhancement effect as a relative excess absorption
Authors: Kuczumow Andrzej , Holland J. Grenville
Published: May 2005

A new approach to problems associated with enhancement effects in XRF analysis, and by analogy to analysis by electron microprobe and PIXE, is discussed. The concept of enhancement as ‘relative excess absorption’ is introduced. This concept allows an arrangement of mass balances in which the concentration of any given element may be derived explicitly from a set of relationships equivalent to fundamental expressions, such as the Lachance–Traill and Tertian equations for monochromatically excited XRF and the Claisse–Quintin equations for polychromatic excitation. In this new approach the values of μk′(λi or Ei) may be derived, and carry the meaning of apparent mass absorption coefficients for absorption and enhancement effects characteristic of any given pair of elements. Finally, some obvious convergences between XRF, electron microprobe and PIXE analyses are emphasized.
Repeated intensity measurements for X‐ray fluorescence analysis of thin samples and evaluation of a scattered line as an internal standard
Authors: Iwatsuki Masaaki , Ito Makoto , Shimizu Hisae , Endo Masashi , Fukasawa Tsutomu
Published: May 2005

Peak intensities of Fe Kα and scattered W Lα were repeatedly measured on 10‐μg iron‐impregnated and blank pieces of filter‐paper, repeatedly remounted or as mounted, at their 20 angles reset or as set, by the fixed‐time method at various times. Relative standard deviations (RSDs) of the Fe Kα intensity and Fe Kα/W Lα intensity ratio and the detection limit (DL) of iron were compared among these repeated measurements. With a constant total counting time, subdivision of the total time into a large number was preferable for the trace analysis of impregnated thin samples. Slight variations in the sample mounting had a large effect on the RSD and DL, whereas variation in the angle setting had a negligible effect. The use of the scattered W Lα intensity as an internal standard had no advantage in the trace analysis of thin samples.
Effect of coster–kronig transitions on L3 sub‐shell x‐ray fluorescence cross‐sections
Authors: Rani Anita , Nath N. , Chaturvedi S. N.
Published: May 2005

Coster–Kronig processes are radiationless transitions in which an inner‐shell vacancy is transferred from one subshell of an atom to another that is less tightly bound, both belonging to the same principal shell. Experimental measurements were carried out on a few elemental samples to examine the effect of Coster–Kronig transitions on fluorescence cross‐sections for the Lα x‐ray line using 22.6 keV Ag K x‐rays for excitation. Absolute values of Lα cross‐sections were also calculated with incorporation of the enhancement due to the Coster–Kronig effect for the elements in the range 41 ≤ Z ≤ 92 at the same excitation energy. A windowless Si(Li) detector system with an energy resolution of 145 eV at 6.4 keV x‐ray energy was used. Thin‐film samples were employed to minimize the self‐absorption effect. Reasonably good agreement was observed between the expected and measured values.
Microbeam technique for energy‐dispersive x‐ray fluorescence
Authors: Rindby A. , Engström P. , Larsson S. , Stocklassa B.
Published: May 2005

By using the total reflecting properties of x‐rays inside glass capillary tubes, intense fine or microbeams of x‐rays can be obtained. In combination with conventional diffraction x‐ray tubes, microbeams with a diameter of a few micrometres and with an intensity sufficient for trace element analysis can be achieved. The basic physics behind the capillary technique is reviewed and an energy‐dispersive x‐ray fluorescence microbeam spectrometer for trace element analysis is described. Examples of applications of the microbeam spectrometer are given and the future perspectives of the capillary technique are discussed.
Backscattering of 10–35 keV electrons from thick targets at normal incidence
Authors: Del Giorgio M. , Trincavelli J. , Riveros J. A.
Published: May 2005

Energy distributions of backscattered electrons were obtained by Monte Carlo simulations for a wide range of elements for electron beams at normal incidence and with energies Eo between 10 and 35 keV. These spectra were compared with experimental data and with a theoretical expression. An analytical expression was fitted to the simulated data. An expression for the backscattered electron coefficient η as a function of atomic number Z and incident energy Eo was obtained. A model for η and the energy distribution of backscattered electrons for multielement samples is suggested.
EXAFS measurement with laboratory equipment: Problems and their countermeasures
Authors: Okamoto Tokuhiko , Yamashita Seiichi , Yamaguchi Toshio , Wakita Hisanobu
Published: May 2005

Experimental techniques for eliminating the characteristic x‐rays emitted from impurities in cathode and anode materials in the vicinity of the x‐ray absorption edge were studied with a laboratory EXAFS spectrometer using a rotating anode. Two methods are proposed for this purpose, a current‐control system and a filter method involving the use of a material that selectively absorbs characteristic x‐rays. The former method was applied to the Co, Ni and Zn K absorption spectra and the latter to a Pd K absorption spectrum, and the results were compared with those obtained from conventional measurements. The change in the nearest neighbour structure of Pd in a Pd‐Al2O3 catalyst accompanied by oxidation or reduction was clarified by EXAFS and XANES measurements with the use of the filter method.
Determination of forms of sulphur in plant material by x‐ray fluorescence spectrometry
Authors: Pinkerton A. , Norrish K. , Randall P. J.
Published: May 2005

A method is described for the determination of S6+ (sulphate) and Sc (C—S bonded sulphur) in plant material by x‐ray fluorescence spectrometry which is considerably more simple and rapid than the chemical determinations of the corresponding sulphur forms.
Two simple, practical correction procedures for spectra processing in energy‐dispersive x‐ray spectrometry
Authors: Eggert F.
Published: May 2005

Procedures are presented for reducing the complexity of common energy‐dispersive x‐ray emission spectra. The methods are two rapid and simple spectra‐processing tools that eliminate, channel by channel, both the escape effect and all Kβ lines coupled to the corresponding Kα lines. An outline of problems related to the escape‐effect correction and Kβ line stripping is given. Listings of programs in Turbo‐Pascal are presented.
A PIXE data reduction code utilizing an IBM PC
Authors: Hallak A. B. , Al‐Kofahi M. M. , Al‐Juwair H. A.
Published: May 2005

Using a data library of element‐specific x‐ray energies and their relative intensities in PIXE, a computer code named MAXE (material analysis by x‐ray emission) was written for spectrum deconvolution and inspection. Subroutines were included for peak identification, background continuum generation, system calibration, peak deconvolution and peak‐area determination. The background is fitted in parts by an exponential function which allows excellent background generation for any matrix. In addition, combined data collection from the RBS and PIXE set‐ups in the same chamber is possible thoough the code. This allows for double checking of the elemental composition and a wide coverage of the elements that are present in the sample matrix. A performance test of our code compared with a widely used program (AXIL) for PIXE analysis showed good agreement.
Versatile and accurate trace element determinations in iron‐rich and other geological samples using x‐ray fluorescence analysis
Authors: Croudace Ian W. , Gilligan Jon M.
Published: May 2005

The reliable, routine XRF determination of trace elements in iron‐rich geological samples, such as banded iron formations, oolitic ironstones and ferromanganese nodules, has until recently been limited. The scattered radiation method (using Compton scattering), well established in normal silicate rock analysis, was developed for the determination of trace element concentrations in diverse rock compositions. Single calibration lines are used for each trace element and serve to provide data over broad sample compositions, ranging from 0 to 70% Fe2O3. A critical evaluation of the calibration lines obtained and the results of trace analyses of synthetic mixtures showed the method to be readily capable of providing accurate chemical data.
Use of theoretical accurate binary influence coefficients with Tertian's equation in x‐ray fluorescence analysis of silicate rocks in borax glass beads
Authors: Muia L. M. , Van Grieken R.
Published: May 2005

A study of the suitability of the Tertian algorithm using new ‘accurate’ binary influence coefficients and a comparison standard for x‐ray fluorescence analysis of geological materials prepared as borax glass beads was performed. The algorithm was found to give satisfactory results for the analysis of four major components in geological materials. Even in the worst case, when there is a factor of 20 difference in the concentration in the specimen and a comparison standard, the algorithm gives results which differ from the true results by a factor of about 2. This makes the algorithm attractive as a diagnostic tool in analyses of unknown specimens and in the identification of appropriate standards. The binary coefficients are easily calculated so that the algorithm can be implemented on a minicomputer.
Study of mean excitation energy and K‐shell effect for electron probe microanalysis
Authors: Brizuela Horacio , Riveros José Alberto
Published: May 2005

The K‐shell correction to stopping power developed by Livingston and Bethe and its influence on electron microprobe analysis are discussed. A comparison among models for the mean excitation energy J given by different workers was made. Two new expressions for J as a function of atomic number Z are suggested for the microanalysis of samples with K‐shell effects: one from stopping power experimental data and the other one from Chu and Powers' theoretical calculations. Livingston and Bethe's K‐shell correction was applied to both new models.
Trends in quantification in XRF
Authors: Vrebos B. A. R. , Kuipéres G. T. J.
Published: May 2005

Trends in the areas of analysis of low atomic number elements, routine quantitative analysis, matrix correction methods, qualitative analysis, set up and calibration, data processing and lower limits of detection are given, based on a short overview of the past, and extrapolating to the future.
Compact synchrotron radiation light source covering the soft x‐ray to the ultraviolet spectral region
Authors: Nakabushi Hiromitsu
Published: May 2005

The compact superconducting synchrotron radiation source AURORA is being developed for industrial use, especially for x‐ray lighography. This source can also be used for research purposes. A prototype machine has been constructed to demonstrate the performance and to study various applications. Acceleration and storage of electrons in the ring was recently achieved. A storage current of 20 mA at 650 MeV energy is attained and the beam lifetime is more than 20 h. The half‐integral resonance injection method has been proved to work well. Further improvements are being studied, including that of the performance of the injector.
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

The 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

A 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

Addition 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

The 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

The 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

Total 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

Three 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

The 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

A 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

A 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

A 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

The 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

A 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

Concentration 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

The 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

If 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

The 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

X‐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

A 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

A 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.
A fast x‐ray counting system
Authors: Short M. A. , Bonner E. J. , Stephenson K. J.
Published: May 2005

An unusually fast x‐ray detector and pulse processing counting system has been devised and tested. The overall dead time of the system was determined experimentally to be 42 ns.
Determination of nearest neighbour distances of some nickel systems from XANES
Authors: Singh V. K. , Chetal A. R.
Published: May 2005

XANES 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

A 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

A 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

A 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.