bluuebunny/crossref_metadata_2025_split huggingface dataset:
X‐ray fluorescence analysis without standards
Authors: Mantler M. , Ebel H. 
Published: May 2005

AbstractTheory and experimental results from X‐ray fluorescence analysis without standards are presented. The composition of an unknown specimen is calculated from its count rates without the use of standard specimens. A fast algorithm employing linear approximation techniques uses these normalized count rates as start values for the concentrations and delivers final results usually after the second or third iteration. Accuracy is typically around 10% relative and can be improved by system calibration with standards of arbitrary composition.
Experimental evaluation of the Rhodes–Hunter model for the particle size effect in X‐ray fluorescence analysis of ‘thin’ samples
Authors: Hołyńska Barbara , Markowicz Andrzej 
Published: May 2005

AbstractThe experimental evaluation of the Rhodes–Hunuer model of the particle size effect in X‐ray fluorescence analysis of ‘thin’ and monolayer samples is reported. The calculations and experiments were carried out for samples of iron oxide(Fe3O4) and copper sulphide (Cu2S) having particles of one size and a histog am distribution of particle sizes. For iron oxide particles, it was found that sticking causes a significant systematic discrepancy between the experimental results and the Rhodes–Hunter model prediction. For copper sulphide particles the model was applicable.
A theoretical procedure to determine coefficients from the Rasberry–Heinrich calibration curve in XRF spectroscopy
Authors: Mainardi R. T. , Fernández J. , Bonetto R. , Riveros J. A. 
Published: May 2005

AbstractRelative X‐ray fluorescent intensity data have been generated numerically for binary samples under mono‐chromatic excitation in those cases of absorption plus enhancement that are dealt with in this work. These data were fitted to the empirical Rasberry–Heinrich equation, keeping both coefficients different from zero, since from our numerical calculations it is shown that in most cases the best fit is achieved when A ≠ 0. Furthermore, this approach shows that a third coefficient introduced into the empirical equation improves the fitting. The aforementioned results suggest that the empirical equation could be deduced from the theoretical equation of fundamental parameters under suitable approximation. The result is an equation similar to that of Rasberry and Heinrich, from which analytical approximated coefficients are obtained. It is then possible to calculate a calibration curve using fundamental parameters values.
Application of scanning electron microscopy in the analysis of the 2:1 group of clay minerals: Vermiculite
Authors: Patel M. 
Published: May 2005

AbstractVarious pretreatments required for analysis of vermiculite minerals by scanning electron miscroscopy are described. It is shown that lyophilized samples exhibit more characteristic and reproducible micrographs than when simply dried in air. The mineral should e preheated in vacuum at 150°C to aviod the risk of exfoliation. In view of the fragile structure of clay minerals, polishing of the solid is to be avioded.
Chemical effects on X‐ray K emission spectra of calcium in various compounds
Authors: Yasuda S. , Kakiyama H. 
Published: May 2005

AbstractA systematic investigation of the chemical effects on the calcium X‐ray K emission spectra from 32 chemical compounds was carried out using a two‐crystal X‐ray spectrometer. The observed chemical shifts of the Ca Kα1,2, Kα3,4, Kβ1,3 and Kβ5 lines relative to the respective lines from CaF2 varied in the range +0.06 to +0.30, +0.09 to +0.32, −0.06 and +1.1 to +3.2eV, respectively. A certain dependence on the nature of surrounding groups was found in these shifts. The profile changes in the Ca Kβ5 and Kβ bands from all compounds were discussed by subdividing them roughly into three types, depending upon their characteristic features.
A Gaussian expression to describe ϕ(ρz) curves for quantitative electron probe microanalysis
Authors: Packwood R. H. , Brown J. D. 
Published: May 2005

AbstractIt is shown that the depth distribution of X‐ray production in the electron microprobe can be accurately described by a Gaussian modified at the sample surface by a transient. Assuming that the Gaussian is a consequence of the electrons undergoing a random walk in the sample and that the transient corresponds with the change from collimated to random electron trajectories enables theoretical values for the amplitudes and coefficients of the two functions to be predicted. There is excellent agreement between the predicted and the observed values. The Lenard coefficient and the electron range can both be estimated from the coefficient in the Gaussian. It is suggested that for microprobe work, Lenard's law for electron absorption be replaced by this revised law. Both the absorption and atomic number corrections of the traditional ZAF approach are replaced by the new function.
Matrix effects in the x‐ray fluorescence method
Authors: Kuczumow Andrzej , Rzaçzyńska Zofia , Szewczak Marek 
Published: May 2005

AbstractThe matrix effects which exist in x‐ray fluorescence analysis are considered, Shiraiwa and Fujino equations being the initial point of these considerations. Matrix effects are divided into two groups: simple and so‐called unusual. Among the simple ones, absorption and enhancement effects are considered. New concepts of ‘absolute’ and ‘relative’ absorption effects are introduced. It is shown that the expressions of simple matrix effects can be easily separated in the Shiraiwa and Fujino equation. Additionally, the unusual matrix effects, including the Birks‐Harris effect and some cases of the Mitchell‐Kellam effects, were found to be well described by certain equations based on the Shiraiwa and Fujino equation, provided the appropriate assumptions were made.
Quantitative electron probe microanalysis using Gaussian ϕ(ρz) Curves
Authors: Brown J. D. , Packwood R. H. 
Published: May 2005

AbstractThe Gaussian expression for ϕ(ρz) has been used as the basis of a computer program for quantitative electron probe microanalysis. Corrections for absorption and atomic number are combined within the expression for ϕ(ρz) whereas the fluorescence correction is based on numerical integration over the primary and secondary intensities. Error histograms based on about 500 published analyses of standard specimens have been used to adjust the parameters in the Gaussian expression for optimum accuracy. The resultant error histograms are as narrow as those obtained for the most accurate of the current ZAF correction procedures. Extension of the method to non‐normal electron incidence is relatively straightforward.
Quantitative x‐ray fluorescence analysis by use of fundamental influence coefficients
Authors: Broll N. , Tertian R. 
Published: May 2005

AbstractThe rigorous relationship existing between effective fundamental coefficients, as expressed by Tertian's identities, and Sherman's basic equations for x‐ray fluorescence intensities is recalled. The properties of these coefficients in the case of binary systems are described, for usual as well as for some anomalous situations, and a general, accurate hyperbolic equation is suggested to account for coefficient variation with composition. The properties of effective coefficients in the general case of multicomponent systems (alloys, etc.) are then examined, and illustrated on the typical FeNiCr ternary system, confirming the essential exactness of this approach. As a consequence, the authors propose to make use of calculated effective coefficients to apply mathematical matrix corrections, and give a first outline of the analytical procedure.
Determination of composition and thickness of TiNxOy films on silicon by combined x‐ray and nuclear microanalysis
Authors: Armigliato A. , Garulli A. , Rosa R. , Berti M. , Drigo A. V. , Desalvo A. 
Published: May 2005

AbstractThe stoichiometry and thickness of TiNxOy films has been determined by electron microprobe and nuclear microanalysis. The difficulty arising in the electron microprobe from the interference between NKα and TiLI lines has been overcome by using a suitable Monte Carlo computing scheme. This procedure takes into account the SiKα intensity which was found to be sensitive to composition and thickness of the overlying TiNxOy film. The good agreement between electron microprobe and nuclear microanalysis results indicate the validity of the method.
X‐ray fluorescence analysis with a linear polarized beam after bragg reflection from a flat or a curved single crystal
Authors: Wobrauschek P. , Aiginger H. 
Published: May 2005

AbstractImprovements of the detection limits in photon induced x‐ray fluorescence analysis are obtained by the reduction of the radiation background using linear polarized x‐rays for excitation. A single crystal where Bragg reflection takes place at an angle 20 = 90° produces linear polarized and monochromatic x‐rays. The use of a single crystal instead of amorphous scattering materials increases the intensity of the polarized beam in some cases up to a factor 104. The use of curved crystals instead of standard flat crystal geometries shows a further increase in the intensity of the exciting beam in the focus line. The crystals in use for both geometries are described. Samples can be investigated in either form, liquid or solid, no special preparation technique is required. Detection limits are given for some elements, absolute amounts of 150 picogram can be detected in some cases.
Properties of intrinsic germanium detectors at low engergies by escape peak spectroscopy
Authors: Rosner B. , Mingay D. W. 
Published: May 2005

AbstractThe study of the energy resolution and linearity of germanium, x‐ray detectors at very low energies is difficult due to the degradation of the spectral line shapes resulting from incomplete charge collection in the detectors's surface dead layer. The use of low‐energy, K escapes peaks obviates this difficulty as they are absorbed at depths characteristic of their full‐energy parent photons. Measurements have been performed using particle‐induced x‐ray emission analysis of targets having characteristic K and L x‐ray energies just above the Ge K‐edge. The escape peaks retain pure Gaussian shapes down to the noise level of the detector and open up the possibility of a selective field of high‐resolution escape‐peak spectroscopy.
Application of the linear relationship between the reciprocal of analyte‐line intensity and the reciprocal of concentration to the analysis of geological materials
Authors: Huang Chung‐Hsi , Smith T. E. 
Published: May 2005

AbstractThe linear relationship between the reciprocal of analyte‐line intensity, and the reciprocal of concentration has been applied to the determination of ten major and minor elements in silicate rocks and minerals. The analyses were carried out on fused specimens of 11 rock standards, with and without added La2O3, and with and without added NaNO3. The method requires no absorption matrix effect corrections, and is ideally suited to the analysis of geological materials with a wide range of chemical composition. It clearly has the advantage of simplicity and speed, and can be applied to the analysis of samples when suitable standards are not available. The results obtained in all cases are in excellent agreement with the literature. However, the discs with La2O3 added yield results with better precision and accuracy than do those without La2O3. Na2O is normally determined on separately prepared rock powder pellets, but can be satisfactorily analysed by this method, using the La2O3 added discs, together with all of the other major and minor elements. Na2O analyses are more readily obtained using discs without added NaNO3. We, therefore, recommend that the analysis of geological materials be carried out on fused glass discs with La2O3 added and without NaNO3.
Limitations in the use of the peak‐to‐background method for quantitative analysis
Authors: Rez Peter , Konopka John 
Published: May 2005

AbstractThe use of peak‐to‐background ratios has been suggested for the analysis of particles or rough surfaces as the peak‐to‐background ratio is assumed to be independent of geometry. The validity of this assumption is examined for flat specimens. It is shown that the peak‐to‐background ratio does not vary much with sample orientation but does vary with voltage, tending to a limit at high voltages. Methods of analysis using the peak‐to‐background ratio are proposed and the effects of fluorescence are discussed.
Proton and photon‐induced x‐ray fluorescence intensity from a monolayer sample of complex chemical and granular composition
Authors: Volkov V. F. , Krasnopolskaya N. N. 
Published: May 2005

AbstractA probability method is used to describe the processes of characteristic x‐ray fluorescence excitation and absorption in a heterogeneous monolayer of particles. Based on this the analytical dependence of the characteristic x‐ray peak intensity on the sizes and shape of particles, and the distribution of elements among the particles is inferred, for two kinds of spectrum excitation. Theoretical evaluations for applying boundaries of the ‘thin’ homogeneous layer model to a heterogeneous monolayer are given. The elements to be determined in unknown compositions are S, Fe and Pb.
Trace element analysis of silicates by means of energy‐dispersive x‐ray spectrometry
Authors: Johnson Robert G. 
Published: May 2005

AbstractThree methods for the energy‐dispersive x‐ray spectrometric analysis of trace elements in silicate rock samples were compared. The comparisons were based on three new USGS reference samples, DNC‐1, W‐2, and BIR‐1, and two established reference samples, G‐1 and W‐1. A loose powder sample preparation was used in the analysis of selected trace elements, including Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb and Ba. For one method, the ratio of analyte line intensity to either Compton or Compton and Rayleigh scatter intensity for a series of standards was used to construct calibration graphs. The other two methods involved fundamental parameter calculations which required a knowledge of the total sample compositions in order to perform the necessary matrix corrections. The results showed good accuracy for all three methods, but those obtained from the ratio–calibration graph method were slightly better than those from the other two methods.
Method of spectral background evaluation using higher energy peaks in x‐ray energy analysis
Authors: Cirone R. , Gigante G. E. , Gualtieri G. 
Published: May 2005

AbstractA method for spectral background evaluation in x‐ray energy analysis is proposed, based on a simple model of background generation in the detector. This model assumes that photons, of a given energy, interacting with the detector have probabilities of generating background counts within lower energy windows. The usefulness of the method resides in the fact that it allows a background evaluation with different levels of complexity and accuracy. The method also permits accurate background calculation with samples of variable mass and composition, such as biological and environmental materials.
Sub‐surface charging, a source of error in microprobe analysis
Authors: Graham J. , Butt C. R. M. , Vigers R. B. W. 
Published: May 2005

AbstractQualitative microprobe analysis of sodian potassian hydroxonian meta‐autunite failed to reveal any sodium, although nearly 3% was present. Potassium, magnesium and calcium were underestimated to a smaller extent in related natural and synthetic structures. The effect is due to the migration of these interlayer cations from the analysed region—almost instantaneously in the case of sodium—and a consequent decrease in count rates, under the influence of the space‐charge resulting from the incident electron beam. Experiments with the autunites and with a soda‐glass subjected to various coating treatments showed that the effect of charging can be dramatic. Such charging also occurs when alkali metals are not present, a fact which has important implications for all microprobe analyses.
K‐absorption edges of cobalt in its metallic soaps and their liquid crystalline solutions in benzene
Authors: Nigam Amar Nath , Rajput Om Prakash , Srivastava B. D. 
Published: May 2005

AbstractX‐ray K‐absorption edges of cobalt in some metallic soaps (myristate, palmitate, stearate and oleate) and their solutions in benzene have been recorded. The latter are liquid crystals. The bond length between the metal and the ligand was found to be greater in solutions than in the solids.
Quantitative light element analysis using an energy‐dispersive detector: 3—practical assessment of accuracy and sensitivity
Authors: Bloomfield D. J. , Love G. , Scott V. D. 
Published: May 2005

AbstractA comparison has been made between light element (5 < Z < 11) analyses performed using energy‐dispersive and wavelength‐dispersive spectrometry. It is shown that, provided appropriate spectrum processing methods are adopted, the two sets of data agree to within 2–3%. Since there is every reason to believe the wavelength‐dispersive measurements are accurate, this demonstrates the feasibility of carrying out quantitative light element analysis by the energy‐dispersive technique. The minimum concentrations of carbon, nitrogen and oxygen which can be detected in selected matrices have been established and it is shown that sensitivities of better than 0.5 wt% are achievable if the electron probe voltage is carefully chosen.
Rapid, high‐quality major and trace element analysis of powdered rock by X‐ray fluorescence spectrometry
Authors: Rose William I. , Bornhorst Theodore J. , Sivonen Seppo J. 
Published: May 2005

AbstractRapid and high‐quality major and trace element data can be obtained by automated x‐ray fluorescence (XRF) analysis of pressed rock powder pellets. The sample preparation procedure is simple, quick and can be done well with minimal supervision. Analysis of the rock pellet for 22 elements requires about 1 h of machine time. The system is calibrated by use of multiple international rock standards and employs a ratio standard for all measurements. Most calibrations are simple linear fits between intensity and concentration. The precision of the major element results are generally better than ±1% of the amount determined, whereas the trace element precisions are generally less than 5%, except when the value determined is close to the detection limit. Accuracies are comparable to those of other published XRF rock analysis procedures.
Limiting values of matrix effects in XRF analysis and some of its consequences
Authors: Kuczumow Andrzej , Szewczak Marek 
Published: May 2005

AbstractThis 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

AbstractA 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

AbstractA 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

AbstractThe 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

AbstractThe 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.