bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of an x‐ray backscattering method to the analysis of ash from some indian coals
Authors: Narayana D. G. S. , Umamaheswara Rao K. , Venkateswara Rao N. , Satyanarayana G. , Sastry D. L. , Bhargava R. C. , Agarwal S. L.
Published: May 2005

An x‐ray fluorescence technique involving a 30 mCi 238Pu as a source of primary radiation and a two‐channel thin NaI(Tl) crystal spectrometer was developed for the analysis of coal ash samples. The geometry of the source–target–detector assembly is described. The ash content is estimated using an x‐ray backscattering method which includes compensation for iron x‐ray fluorescence. About 120 Indian coal samples were analysed and the results show that the ash content varies from 10 to 40%.
Application of an empirical correction method for the x‐ray fluorescence analysis of copper alloys
Authors: Kovács P. , Kis‐Varga M.
Published: May 2005

An improved energy‐dispersive x‐ray fluorescence analyser has been used in a copper smelting works. An empirical correction program with α parameters according to the Lachance–Traill algorithm has been applied. The concentrations of eight elements in brass, red brass, bronze and albronze have been determined with acceptable accuracies.
XANES study of two bivalent cobalt polymers
Authors: Chattopadhyay S. , Mande C. , Juneja H. D. , Munshi K. N.
Published: May 2005

XANES (x‐ray absorption near edge structure) in the vicinity of the K absorption edge of cobalt has been studied for two bivalent cobalt polymers, viz. cobalt(II) azelaic acid bis(phenylhydrazide) and cobalt(II) sebacic acid bis(2,4‐dinitrophenylhydrazide), using a bent crystal x‐ray spectrograph of the Cauchois type. This study helped in the determination of the average bond lengths in the two compounds. The study of the chemical shifts and the edge widths throws some light on the relative covalency in these complexes.
Improved determination of cobalt in steel by x‐ray fluorescence analysis
Authors: Sieber John R. , Pella Peter A.
Published: May 2005

A method for improving the determination of cobalt as a minor element in steel specimens is reported. A line overlap correction for the contribution of the Fe Kβ background on the Co Kα peak plus inter‐element matrix corrections is necessary in the determination of Co when standards of varying matrix compositions are used. Co was determined in several NBS SRM steels and values were found that agreed with the certificate values to within 5% relative error in the range 0.005–0.40 wt‐% cobalt.
Effect of relative L‐line intensity ratios on the accuracy of standardless x‐ray microanalysis
Authors: Lábár János L.
Published: May 2005

A standardless method for energy‐dispersive x‐ray microanalysis has been implemented. Pure element intensities were calculated from first principles. The spectrum processing and ZAF correction of the unknown spectra were effected by a modified FRAME‐C program. The replacement of the original constant relative L‐line intensities with Z‐dependent new values according to Schreiber and Wims improved the analytical accuracy of the program. The improvement is demonstrated by a better consistency of the measured and calculated L‐line intensities of pure elements and by the reduction of the RMS error from 15.2% to 8.5%, calculated on the basis of 64 analyses of compound standards measuring K and L line intensities.
Precipitation technique to prepare thin‐film standards of lead and zinc for x‐ray fluorescence spectrometry
Authors: Pang Thomas W. S. , D'Onofrio Anthony M. , Lo Francis B. , Arai Douglas K. , Nazar Mark A.
Published: May 2005

Thin‐film standards of lead and zinc were prepared by precipitating precise amounts of their insoluble salts directly on to polyamide film substrates for the calibration of the x‐ray spectrometer. Samples of different particle deposition characteristics were then prepared and analysed by XRF, atomic‐absorption and inductively coupled plasma atomic‐emission spectrometry. The optimum sizes of thin‐film specimens were selected to be the same as the area of the specimen plane where the average flux of the primary x‐ray beam is fairly uniform. No significant difference in response of the spectrometer to the Zn Kα and Pb Lβ between the samples and the standards were observed. The correlation of the XRF results with those obtained by the other two methods was found to be 1.008±0.029 for lead and 0.995±0.020 for zinc. The amount of metal present ranged from about 5 to 350 μg for lead and from 10 to 600 μg for zinc.
X‐ray fluorescence studies on low‐Z elements of straits chinese porcelains using Fe‐55 and Cd‐109 annular sources
Authors: Yap C. T.
Published: May 2005

Elemental analysis from Z = 13 (aluminium) to Z = 27 (cobalt) was made on 37 pieces of Straits Chinese porcelains using energy‐dispersive X‐ray fluorescence technique. These porcelains were produced from the beginning of the nineteenth century up to the Republic period (1912–1939) except 4 pieces which were made recently. It was found that manganese, cobalt, potassium and, to a certain extent, iron were correlated in time. All Ch'ing and Republic pieces containing underglazed blue had Mn/Co ratios between 2 and 4 while the modern pieces had Mn/Co ratios of less than 0.07. A plot of the ratio of the intensity of KKα,1 to that of the coherently scattered MnKα from the Fe‐55 source versus the ratio of the intensity of the FeKα,1 to that of the coherently scattered AgKβ from the Cd‐109 source shows that all Ch'ing and Republic pieces cluster together and are quite distinct from the modern pieces. XRF technique therefore provides a simple, fast and, most important of all, non‐destructive method of identifying modern (post World War II) fake reproductions of Straits Chinese porcelains.
SEM studies on silica from plant materials
Authors: Prasanna P. , Patel M.
Published: May 2005

The Silica structural framework in plant materials can be separated from the organic part by acid leaching and can be examined by SEM. Scanning electron micrographs characterizing the bonding and distribution patterns of silica in rice husk, rice straw and sugarcane leaves are presented. The differences in the surface morphology of the three plant products are discussed.
Analysis of fused samples using influence coefficients obtained from synthetic standards
Authors: Ward J. , Valdes J.
Published: May 2005

A mathematical approach is presented which permits a simple calculation of influence coefficients using intensities measured in a set of suitably chosen synthetic standards. A set of n standards suffices for obtaining all the coefficients necessary for the analysis of a matrix with n elements. An evaluation of such coefficients has been carried out for silicate‐type samples. The results show that if theory is guided by some practical considerations, highly effective coefficients can be obtained. The method can be applied to several types of substances that require fusion prior to analysis.
Effect of some important sample parameters on the X‐ray fluorescence determination of impurities in pure materials: Determination of Ca, Y, Gd and Th in uranium
Authors: Agrawal R. M. , Kapoor S. K.
Published: May 2005

Calibration standards obtained by dry mixing of the components in appropriate proportions may be compositionally accurate but they can be a major source of error in the X‐ray fluorescence analytical results owing to the mismatch in the degree of their homogeneity with that of the sample. An in‐depth study has been made on the above aspect taking U3O8 as a matrix and Ca, Y, Gd and Th in the low concentration range (0—1500 ppm) as representative impurities. This study clearly illustrates the incompatibility of the truly homogeneous standards with the standards obtained by dry mixing and grinding. This incompatibility is dependent on the analytical line wavelength, being large for soft X‐ray lines and small for harder X‐rays.

The effect of binding material which is often required for briquetting the sample into a pellet form and is necessarily to be mixed with the sample by dry mixing is discussed.
Comparison of experimental relative efficiencies for different Si(Li) detectors in the energy range, 4.5–17.5 keV
Authors: Yap C. T. , Kump P. , Tang S. M. , Bilal M. G.
Published: May 2005

The relative efficiencies of four Si(Li) detectors from three different manufacturers were studied. The results show that such efficiencies depend not only on the shape and size of the detector's sensitive volume but also on the collimator assembly and centralized or off‐centre mounting of the crystal within the cryostat. It is therefore necessary to calibrate the XRF spectrometer in the same geometric configuration which will be used for the intended application in elemental analysis; calculated model‐dependent efficiencies can be very different from experimental efficiencies.
Application of the coherent‐to‐incoherent intensity ratio to the measurement of mineral matter in coals
Authors: Dale L. S. , Matulis C. E.
Published: May 2005

The relationship between the scattering of X‐rays from coal samples and their chemical composition has been investigated using a theoretical model based on the concept of the isolated atom. Model calculations were used to assess the coherent‐to‐incoherent intensity ratio as a means of determining the mineral matter content of coals, and the scope of this application was studied in detail. The procedure was verified theoretically by using the model on a set of well characterized coals. Using a relatively simple calibration procedure the experimentally determined mineral matter agreed with the radiofrequency ash values to within 7.6% rms.
Routine method of X‐ray spectrometric analysis without standards involving only initial instrumental calibration 2—Practical calculation equations for iteration in an iron‐based alloy system constituted by ten elements and their experimental determination
Authors: Wang Yongzhong , Chen Zhimin
Published: May 2005

Based on the theoretical equations for calculations in X‐ray fluorescence spectrometric analysis without standards in Part 1, a set of equations for practical iteration applied to an iron‐based alloy constituted by ten elements are presented. Some of factors that affect the accuracy of the results are explained and determined. Forty steel alloy specimens were analysed without standards. The results show that the deviations from the results of wet chemical analyses are small, and the geometric configuration of specimen is generally not required.
Elemental analysis of coal ash using energy‐dispersive X‐ray fluorescence
Authors: Rao N. Venkateswara , Raghavaiah C. V. , Satyanarayana G. , Sastry D. L.
Published: May 2005

An energy‐dispersive X‐ray fluorescence spectrometer was used to analyse about 100 samples of coal ash. The elemental concentrations were determined using the standardless method and fundamental parameter approach. It was found that the Fe concentration was as high as nearly 30% in some samples. The results suggest that S, Ca, Ti and Fe are the major components that require corrections to be applied owing to X‐ray fluorescence in the back‐scattering techniques used for the determination of the ash fraction in coal.
An approach to the solution of matrix problems in the XRF analysis of lead–zinc ore by the use of an internal standard and mathematical corrections
Authors: Mahapatra N. S.
Published: May 2005

For the determination of the lead, zinc and iron contents of bore‐hole samples from the Rampura‐Agucha lead‐zinc deposit, X‐ray fluorescence spectrometry has been used. The concentration range of the metals, present in the ore body as galena, sphalerite, pyrite and pyrrohotite, is very wide: for Zn 0—30%, for Pb 0—10% and for Fe 1—16%. An internal standard method and a concentration based correction equation have been used to solve the effect of matrix variations, which is the major problem in the development of the programme.

Copper added as copper sulphate, which also acts as a good binder, was used as an internal standard for zinc. For Pb Lα1 an adjacent Rayleigh diffraction line, Au Lβ1, was used as an internal standard and partially compensates for the matrix effect. The residual correction is made by the use of a mathematical model. For iron, only a mathematical correction is made. There is good agreement between the XRF and wet chemical analysis results for zinc and lead. For iron, the absolute differences are larger, but the correlation coefficient is good for average analysis of a series.
Importance of sample grinding time in X‐ray emission spectrometry
Authors: Novosel‐Radović V. J. , Maljković D. A.
Published: May 2005

The effect of the sample grinding time on X‐ray spectrometric results was examined on real samples (limonite iron ore, sinter mixture and blast furnace slag). Comparative results were obtained for X‐ray diffraction analysis and scanning electron microscopic analysis. The optimal grinding time depended on the type of analyte and on the phase composition of the sample.
X‐ray fluorescence determination of trace element concentrations of zinc and arsenic and their relation to ceramic attribution
Authors: Yap C. T.
Published: May 2005

Absolute values of concentrations of zinc and arsenic for ceramics were obtained using an energy‐dispersive X‐ray fluorescence technique. One hundred and fifteen pieces of Chinese Jingdezhen porcelains from late Ming to 1983, including a few non‐Jingdezhen pieces, were studied. For all pieces of Chinese porcelains made in Jingdezhen from late Ming to the Republic period, the results show that zinc was present in very small quantities (<70 ppm) whereas arsenic was completely absent. However, after World War II, many pieces were found to contain relatively large concentrations of both zinc and/or arsenic. This could then be a simple, non‐destructive method of detecting modern fakes.
Modification of Philibert–Tixier ZAF correction for geological samples
Authors: Fialin Michel
Published: May 2005

Two steps are usually used in electron microprobe correction: (1) development of a theoretical mode based on physical phenomena within pure or binary targets; and (2) simplification of certain complexities due to multi‐element samples by using average coefficients in the theoretical equations. It is proposed to use a more detailed method of estimating the general correction coefficients concerning A/Z relationships in the absorption and ionization terms of the theoretical formulation. In the absorption formulation the factor h is taken as (1.2 ∑ CiAi/Zi2)/ (1 + Ka). The value of a is given as ‐1. In the ionization relationship M = (∑ CiZi/Ai)/(1 + Kb) with b = E0/100, where E0 is the accelerating voltage in kV. K, deduced from experimental results, is given as K = ∑ Ci(Zi ‐ Z¯), where Z¯ is the average atomic number of the target.

These values are derived empirically through direct measurements on samples whose correction properties induce normally strong analytical errors: oxides with 11 ⩽ Z ⩽ 14 analysed within a heavy matrix.
X‐ray K absorption spectroscopic study of some Schiff‐base polymers of cobalt
Authors: Mujumdar P. V. , Deshmukh Prabodhachandra C. , Sapre V. B. , Bhave N. S.
Published: May 2005

The results of a study of the x‐ray K absorption spectrum of cobalt in the elemental form and in some of its Schiff‐base coordination polymers are presented. The K absorption discontinuity of cobalt was recorded together with the x‐ray absorption near‐edge structure (XANES) and extended x‐ray absorption fine structure (EXAFS) associated with it by employing a 0.4 m Cauchois‐type bent‐crystal spectrograph. The (100) planes of a muscovite mica analyser crystal were used for reflection of x‐radiation, the source of which was the tungsten target of a Chirana conventional x‐ray tube. Measurements were made of the chemical shift, edge width, XANES and EXAFS associated with the discontinuity. Levy's theory and the graphical method based on the theory of Stern and coworkers were employed to determine the average radius of the first coordination sphere surrounding the cobalt atom in all the systems studied. The results are discussed in terms of the bond length, bond ionicity, coordination geometry and some other parameters related to the local environment of the absorbing cobalt atom.
Quantitative trace element determination in thin samples by total reflection x‐ray fluorescence using the scattered radiation method
Authors: Yap C. T. , Ayala R. E. , Wobrauschek P.
Published: May 2005

It is shown that samples exposed under total reflection conditions obey the relationship Ii/Iinc = KCi, where Ii is the x‐ray fluorescence intensity due to element i of concentration Ci, Iinc is the intensity of the scattered incoherent radiation and K is a constant. An experiment on the determination of sulphur in diesel fuel confirmed this derivation. This relationship affords a simple and fast method for quantitative trace element determination, requiring virtually no sample preparation and extremely small amounts (<Iμl). Other advantages include its insensitivity to instrumental variations and changes in excitation conditions or in sample characteristics such as particle size and sample amount.
Shape and extended fine structure of the x‐ray K‐absorption discontinuity in some cobalt mixed‐ligand complexes
Authors: Khadikar Padmakar V.
Published: May 2005

Correlation of the variation in the distance between cobalt ions and its nearest neighbours with the variation in the covalency of the metal—ligand bond was estimated from the shape and the extended fine structure of cobalt K‐absorption discontinuity in some cobalt mixed‐ligand complexes.
X‐ray fluorescence analysis of samples with elemental sulphur. Effect of sulphur sublimation
Authors: Chinchón J. S. , López‐Soler A. , Travería A. , Vaquer R.
Published: May 2005

The precautions to be taken during x‐ray fluorescence (XRF) analysis of samples containing elemental sulphur were investigated. Elemental sulphur under vacuum (vacuum required for S Kα analysis) undergoes sublimation. As a result, the sulphur intensity signal diminishes in direct relation to the time during which the sample has been under vacuum. The work power accelerates the sublimation of sulphur. A method for obtaining real analytical values is proposed. The risk to the XRF spectrometer constituted due to sublimed sulphur are pointed out.
Scanning electron microscopic studies of pore formation in mica schist insulating brick
Authors: Patel M.
Published: May 2005

SEM micrographs showing porous structures and bonding of pores through broken mica flakes are presented. Pores of varying dimensions (10–400 μm) are formed. Interlayer spaces in mica are shown to be the preferential direction for heat and subsequently crack propagation during heat treatment for producing cellular insulating bricks at 900°C. The cracks end up with the formation of large pores in the presence of foaming agent and sodium silicate.
Fitness of metallic disc samples for the determination of cerium in cast iron by X‐ray emission spectrometry
Authors: Sofilić T. , Maljković Da.
Published: May 2005

Samples in the form of metallic disc are frequently used in the analysis of cast iron by x‐ray emission spectrometry and give good results for common analyses (determination of carbon, sulphur, phosphorus, silicon, manganese, copper, etc.) because of the uniform distribution of the analyte in the sample. However, the results of the analysis of metallic disc samples of cast iron to which cerium had been added were poor, which could be attributed to a non‐uniform distribution of compounds which cerium formed with sulphur and oxygen. A more detailed investigation of cerium distribution in relation to its content in the sample gave evidence of the presumed non‐uniform distribution. Scanning electron microscopy confirmed the presence of unequally distributed aggregates of different size containing cerium, sulphur and oxygen. On the basis of an examination and comparison of published pretreatment procedures, a modified procedure including cerium precipitation with oxalate without transformation into the oxide form is proposed. Using this method, greater reliability of the results was obtained than in the analysis of cast iron samples without pretreatment, i.e. in the disc form.
A method of correcting dead time and pulse pile‐up errors in energy‐dispersive X‐ray analysis
Authors: Gui‐Nian Diao , Turner K. E.
Published: May 2005

The Barnhart pulse pile‐up and dead time correction method is used by a number of manufacturers of energy‐dispersive x‐ray analysers. This method may provide inadequate correction at moderately high count rates and/or in the presence of low‐energy x‐ray peaks. A correction scheme is proposed to overcome these difficulties and its effectiveness is illustrated by the analysis of several homogeneous mineral samples of well established composition.
Spectral resolution of crystals and detectors in the X‐ray region
Authors: Kuczumow A. , Helsen J. A.
Published: May 2005

The basic definitions of spectral resolution are considered. To the authors' knowledge, the most complete com‐pilation of data on the spectral resolution of different elements of spectrometers is given, with careful comparisons.
Angular dependence of X‐ray fluorescence intensities
Authors: De Boer D. K. G.
Published: May 2005

The x‐ray fluorescence intensity of a sample contains the product of two angular‐dependent factors: the first describes the angular dependence of the absorption of both incident and emitted radiation and the second is a geometrical factor accounting for the angular variation of irradiated and detected surface area. Theory for the angular dependence of x‐ray intensities is presented. Good agreement is found with experimental data, measured with a novel focusing spectrometer using a small silicon detector. Measurement of the angular dependence of intensities is especially promising for the analysis of multi‐layer samples.
Matrix corrections for quantitative determination of trace elements in biological samples using energy‐dispersive X‐ray fluorescence spectrometry
Authors: Kumar Sudhir , Singh Surinder , Mehta D. , Garg M. L. , Mangal P. C. , Trehan P. N.
Published: May 2005

An experimental method for the evaluation of the matrix absorption correction (8) for the determination of trace elements in thick biological samples using EDXRF is discussed. The validity of the method was checked in two ways, first by comparing the experimental values with theoretical estimated values for samples of known matrix and second by analysing NBS biological standards in the form of thick pellets. It was found that a sample thickness of 40‐70 mg cm−2 is, in general, optimum for the analysis of biological samples in pellet form with an excitation energy of 22.6 keV.
X‐ray photoelectron spectroscopic studies on silicon carbide from rice husk
Authors: Patel M.
Published: May 2005

The surface structure of silicon carbide whiskers, produced from rice husk at 1500–1800°C, was examined by x‐ray photoelectron spectroscopy. An ESCA survey scan of the surface showed Si, C, O and F to be present; Si in the form of SiCx and SiOx and C in the form of SiCx and CHx. On sputtering the sample, the SiOx and CHx species were reduced and the SiCx level increased. The photoelectron spectra are presented.
Wear and tear studies of oil‐lubricated machines using energy‐dispersive X‐ray fluorescence spectrometry
Authors: Bhat C. K. , Kaul D. , Lodha G. S. , Koul R. , Sawhney K. J. S.
Published: May 2005

The wear of oil‐lubricated machines was monitored by establishing a correlation between the wear rate of the machine and the concentration of heavy metal contaminants in the lubricating oils used. The concentrations of heavy metal contaminants in the oil were determined using energy‐dispersive X‐ray fluorescence spectrometry. To obtain a representative sample, the procedure for sample collection and preparation was standardized. Samples were collected from a 30 KVA diesel generator set at BARC‐NRL at regular intervals. The concentrations of Fe, Cr and Ni were found to increase with increase in the number of hours in service.
Lα/Lβ; and Lα/Lγ x‐ray intensity ratios for elements in the range Z = 55–80
Authors: Raghavaiah C. V. , Rao N. Venkateswara , Reddy S. Bhuloka , Satyanarayana G. , Murty G. Sree Krishna , Rao M. V. S. Chandrasekhar , Sastry D. L.
Published: May 2005

A systematic study of Lα/Lβ and Lα/Lγ x‐ray intensity ratios was undertaken by measuring the characteristic x‐ray intensities in 23 elements over the range Z = 55‐80, using a 30 mCi 238Pu source of excitation and a high‐resolution Si(Li) detector system coupled to a computer‐controlled multi‐channel analyser. The theoretical predictions due to Scofield were computed for the present energy (weighted average) of 15.28 keV excitation and compared with the experimental values. The experimental values of Lα/Lβ and Lα/Lγ versus Z were fitted to a fourth‐degree polynomial, and most probable values of Lα/Lβ and Lα/Lγ at each Z were also determined using this fit.
Study of K‐absorption edge of selenium in the glassy semiconducting Se100−xInx system
Authors: Kumar Arvind , Husain M. , Swarup S. , Nigam A. N. , Kumar A.
Published: May 2005

The shift of the K‐absorption edge (δEk) was measured in Se100‐xInx binary system where 0 ≤x ≤ 30. The K‐edge of Se progressively shifted toward the lower energy side as the In concentration increased from 0 to 15 at.‐%. However, at higher concentrations, the relative shift started to decrease. The results are in accordance with Pauling's concept of electronegativity and indicate that the nature of the bonds is iono‐covalent in these glasses, as found in many crystalline solids. The composition dependence of the edge shift is also discussed in terms of the structure of Se.
Determination of sample thickness via scattered radiation in x‐ray fluorescence spectrometry with filtered continuum excitation
Authors: Araújo M. Fátima , Van Espen P. , Van Grieken R.
Published: May 2005

A semi‐empirical approach is described for determining the mass per unit area of a sample being analysed. The method can be used to estimate the concentration of minor and trace elements in matrices containing a substantial amount of light elements. The procedure utilizes the coherently and incoherently scattered radiation induced in the sample by the filtered continuum radiation of a rhodium x‐ray tube. The relationship between the intensity of the scattered radiation per unit mass and the average atomic number of the sample is established via calibration graphs, which can be applied for different x‐ray tube voltages and for different primary beam filters. The overall procedure was validated by the analysis of several geological standards, deposited as thin slurries of unknown thickness either on Mylar foil or on Nuclepore filters.
Characterization of II–VI semiconductor materials using surface analytical techniques
Authors: Kibel Martyn H.
Published: May 2005

The production, properties and structure of II–VI semiconductor materials are topics of increasingly intense research activity. This paper discusses the use of the surface analytical techniques x‐ray photoelectron spectroscopy, Auger electron spectroscopy and energy‐dispersive x‐ray spectroscopy to study and characterize these materials, and hence assist in understanding the growth process.
Characterization of II–VI semiconductor compounds grown by metallo‐organic chemical vapour deposition
Authors: Christiansz G. I. , Georgiou S. , Kwietniak M. S. , Pain G. N. , Usher B. , Warminski T. , Glanvill S. R. , Rossouw C. J. , Stevenson A. W. , Wilkins S. W. , Wielunski L.
Published: May 2005

CdTe and HgCdTe epitaxial layers were grown on 50 mm diameter (100) GaAs wafers in a Quantax 226 metallo‐organic chemical vapour deposition system. Dimethylcadmium, diethyl telluride and elemental mercury were used as starting materials in the thermal growth process which takes place in a flow of hydrogen at 250–350°C. The layers were characterized by (1) an interference contrast microscope for surface morphology; (2) FTIR spectros‐copy for compositional and thickness uniformity; (3) x‐ray topography and double crystal diffractometry for the non‐destructive evaluation of the crystalline quality and microstructure; (4) energy‐dispersive x‐ray analysis (WDX/EDX) for compositional studies; (5) transmission electron microscopy for interface observations and analysis; and (6) Rutherford backscattering and channelling analysis for surface stoichiometry and crystal quality determinations.
Some considerations on the use of Lα series of transition metals in electron probe microanalysis: The example of zinc minerals
Authors: Fialin Michel
Published: May 2005

It is shown, using measurements on certain zinc minerals, that the Lα emission of transition metals can be affected as follows. First, the band shape is often changed in the range of the satellite emission which implies, for data acquisition, the use of the total band area instead of the measurements at the peak maximum. Second, the physical process of self‐absorption of Lα photons (here, the absorption of Zn Lα in Zn) depends on the nature of the specimen (metal, semiconductor, insulator), In EPMA, the corresponding theoretical parameter, which is the mass self‐absorption coefficient, may be then changed between an unknown and standard, despite the assumption of constancy in matrix‐effect correction models. Both phenomena are correlated because of their strong dependence on the electronic structure of the M5 level, which can be modified in poor conducting materials by the presence of holes. The choice of suitable standards is then crucial in order to perform accurate k‐ratio measurements.
Fundamental coefficient method applied to a quasi‐monochromatic excitation
Authors: Broll N.
Published: May 2005

The fundamental or effective influence coefficients are derived from the theoretical fluorescence intensities. For a monochromatic excitation, the calculations are simplified and do not require the spectral intensity distribution of the x‐ray tube. The use of the fundamental coefficient method applied to a quasi‐monochromatic excitation is illustrated by a practical application of the analysis of stainless steel and a high‐temperature alloy. The measurements were made with an energy‐dispersive spectrometer.
Glass disk fusion method for the X‐ray fluorescence analysis of rocks and silicates
Authors: Alvarez Moisés
Published: May 2005

A study of the physical and practical aspects needed for a successful solid solution method for XRF analysis is presented in the light of the theory and practice of the glass‐making industry. An inexpensive manual glass disk sample preparation method is proposed that gives a well annealed disk that can be ground and polished without any losses due to breakage.
Quantitative XRF analysis of surface layers: Procedure for the determination of thickness and composition
Authors: Rössiger V. , Thomas H.‐J.
Published: May 2005

Based on a fundamental parameter treatment, a procedure was developed to determine the thickness and composition of surface (multi)layers from measured XRF data. The main features of a computer program are described and some applications are discussed.
Novel method for estimation of the effective nuclear charge (Zeff) on the metal atom on cobalt complexes from the x‐ray absorption discontinuity
Authors: Khadikar Padmakar V.
Published: May 2005

A novel method for estimation of the effective nuclear charge (Zeff) on the central metal atom in cobalt complexes from the x‐ray K‐absorption discontinuity is proposed. Its potential is discussed on the basis of statistical analysis of the data obtained from the results for 25 cobalt complexes which indicated fairly good agreement between the observed and the estimated values of Zeff for the cobalt atom.
Semiempirical model for correction of matrix effects in on‐stream x‐ray fluorescence analysis
Authors: Stoev Krassimir Nedialkov
Published: May 2005

A semiempirical non‐linear model for the on‐stream x‐ray fluorescence analysis of slurries was developed, utilizing the intensities of fluorescent and scattered radiation. It is assumed that the slurry consists of liquid and solid parts. All components of the solids except the elements to be measured are considered to be a filling substance with an approximately constant absorption coefficient. The model permits the calculation of the elemental weight fractions in the solids without the need for the determination of the solid content in the slurry. The accuracy and reproducibility of the method are compared with those of existing multiple regression models. A non‐linear expression for the determination of the solid content in the slurry using the intensity of scattered x‐radiation is proposed and compared with some polynomial regression models.
Evaluation of spectrum overlap correction in energy‐dispersive x‐ray spectrometry using the digital filter deconvolution procedure: Application to selected interferences encountered in the microprobe analysis of minerals
Authors: Potts Philip J. , Tindle Andrew G.
Published: May 2005

An evaluation was undertaken to characterize the accuracy and effectiveness in the deconvolution of energydispersive x‐ray spectra of the overlap correction procedure based on a digital ‘top hat’ filter and least‐squares fitting of library spectra using an algorithm developed by Statham. This deconvolution procedure was applied to x‐ray spectra recorded by electron microprobe to represent interferences that range in severity from minor to severe, specifically overlap between (i) Cr/Mn K lines, (ii) Ba L and Ti K lines, (iii) Au/Pt L and M lines and (iv) Bi/Pb L and M together with S K lines. A novel calibration procedure was used to simulate spectra and so avoid the requirement to obtain and analyse a large number of mineral standards. This procedure involved superimposing x‐ray spectra from individual elemental standards counted for a range of count times suitable for testing the deconvolution program. The results demonstrated that reliable deconvolution could be achieved down to <1% Cr in a manganese matrix, 2.5% Ba in a titanium matrix, <2.5% Au in a platinum matrix (based on either L or M lines) and about 2.5% Bi in a Bi–Pb–S matrix using the M lines of Bi and Pb. Within the fitting error calculated by the deconvolution program, bias from expected values was not detected excepted when Bi, Pb and S were fitted to the simulated spectrum of bismuthite (Bi2S3). Small discrepancies in the Bi and S values were then observed. Overall, it was concluded that in cases of severe overlap, numeric data from the spectrum deconvolution program were a more reliable indicator of the presence of an element than visual examination of the original spectrum.
Energy‐dispersive x‐ray fluorescence analysis of borax beads using double dilution without comparison standards
Authors: Muia L. M. , Van Grieken R.
Published: May 2005

A method for the energy‐dispersive x‐ray fluorescence analysis of geological materials in borax glasses without standards is described. The usefulness of the procedure was demonstrated by analysing five certified sedimentary rock reference materials for Al2O3, SiO2, CaO, TiO2, MnO and Fe2O3. The experimental results show reasonable agreement with the certified values. The method has a theoretical precision of 2% when dilution ratios of 6 and 12 are used. The actual precision of the method ranges from 4 to 15% for these element oxides. For the major oxides considered, the procedure can be useful when certified or well characterized geological standards are not available.
Application of delayed x‐ray spectrometry to the analysis of some rare earth elements
Authors: Pillay A. E. , Mboweni R. C. M.
Published: May 2005

The capabilities of delayed x‐ray spectrometry preceded by isotope‐source thermal neutron activation for the specific determination of some rare earth elements (Sm, Eu, Dy, Ho) in small powdered samples was evaluated. The feasibility study relied heavily on the low‐energy sensitivity of the detector used. Detection of the delayed x‐rays was achieved with a 100‐mm2 Ge detector with the ability to produce optimum photopeak‐to‐noise ratios. The rare earth elements were chosen on the basis of their inherent favourable nuclear properties for producing a practicable x‐ray yield and on the demand for their analysis. Analytical results are presented over a range of concentrations for the elements of interest and the potential of the technique for application to their general routine analysis is discussed. Interferences from the sample matrix can be suppressed to an extent that makes the method almost independent of the matrix. This and other features make the technique a strong rival to conventional activation analysis.
Determination of phosphorus in borophosphosilicate or phosphosilicate glass films on a silicon wafer by wavelength‐dispersive x‐ray spectrometry
Authors: Levine Herman S. , Higgins Karen L.
Published: May 2005

A wavelength‐dispersive x‐ray fluorescence method was developed for the determination of phosphorus in borophosphosilicate glass (BPSG) or phosphosilicate glass (PSG) films on a silicon wafer. Secondary spectral line intensities from the coated wafer are compared with those of an uncoated Si wafer and a fused P standard. The results are then converted to phosphorus content and surface density of the film by equations for the relative spectral line intensities of P and Si with corrections for the shift in the Si peak due to chemical bonding. Results obtained on an annealed set of PSG samples using four different incident spectra were self‐consistent and correlated well with independent inductively coupled plasma atomic emission spectrometric analyses for phosphorus and ellipsometric measurements of thickness. Preliminary results with BPSG samples were promising and showed that results for phosphorus were not sensitive to boron concentrations in the films.
Sample area dependence in quantitative EDXRF analysis
Authors: Boman J.
Published: May 2005

The measurement of small, thin samples with an area of the order of mm2 with the ordinary EDXRF technique requires that special care be taken to include the sample size in the evaluation of element concentrations. Results are reported obtained using a standard procedure for the evalution of small samples used in the author's laboratory. This procedure makes use of an input parameter, viz. a ‘geometrical factor’ corresponding to the sample area which is used in the evaluation software. The results show that an almost straight line can be fitted to describe the parameter as a function of sample area for small samples (with an area of the order of mm2), but that the corrections for inhomogeneity of the beam intensity are needed in many cases. For large samples (with an area of the order of cm2) the parameter is equal to unity.
Comprehensive major, minor and trace element analysis of a submarine polymetallic nodule by wavelength‐dispersive x‐ray fluorescence spectrometry
Authors: Cai Shulin , Guo Yulin , Li Jie
Published: May 2005

A method was developed for the determination of major, minor and trace elements in a submarine polymetallic nodule by x‐ray fluorescence spectrometry. Fusion of the sample was performed in gfraphite crucibles using a 1:3 dilution ratio with an Li2B4O7Li2CO3LiNO3 flux. Calibration was carried out with synthetic standards. The absorption‐enhancement effects for 28 analytes were each corrected using influence coefficients generated by the COLA equation. The results obtained were in relatively good agreement with the recommended values for the Chinese reference material GSPN‐1. The technique of sample preparation and the use of synthetic standards can also be extended to the analysis of other polymetallic ores.
Caveat emptor: Gross refraction effects pose problems in the use of multilayers for soft x‐ray spectroscopy
Authors: Luck Sara , Urch David S. , Zheng Dao Hong
Published: May 2005

First‐ and higher order reflections from a molybdenum‐boron carbide multilayer (nominal 2d 200 Å) have been studied. In the first order the apparent 2d spacing was found to increase, and then to decrease, with increasing wavelength and angle of incidence, whereas for higher orders it increased with order, converging to a limit (2d∞) of about 210.5 Å. Strong refraction effects were invoked to rationalize this behaviour, and the refraction constant δλ was found to vary from 2 × 10−3 to 50 × 10−3 for the wavelength range 23.5−135 Å. Experimental procedures to calibrate multilayers for soft x‐ray spectroscopy, by first determining 2d∞ and then δλ values for various wavelengths, are described.
Characterization of materials by chemical shift of x‐ray absorption edges
Authors: Husain M. , Narula Alka
Published: May 2005

A simple method for the determination of the composition of compounds and alloys by using the data for chemical shifts of x‐ray absorption edges is suggested. It is found that the calculated compositions of compounds are in good agreement with standard composition values.
Trihydroxymethylaminomethane high‐efficiency x‐ray analyser crystal
Authors: Su Genbo , Li Zhengdong , Huang Gongfan , Pan Feng
Published: May 2005

Comparison of the x‐ray analyser properties of trihydroxymethylaminomethane (TAM) and pentaerythritol (PET) crystals showed that the TAM crystal has a higher efficiency.
Measurement of relative intensities of L‐shell x‐rays of some heavy elements using Cd‐109 radioisotope source
Authors: Darko J. B. , Tetteh G. K.
Published: May 2005

The relative L‐shell x‐ray intensities of Sm, W, Ir, Au, Hg, Pb and U were measured using a Cd‐109 radioisotope source and a Si(Li) detector. The measured relative intensities were compared with the theoretically calculated values due to Scofield, computed for the present excitation energy of 22.6 keV. The experimental results were found to agree with theory in most cases.
A compton peak method for incident angle determination in XRF with annular excitation
Authors: Greaves E. D. , Bohus L. Sajo , Marcó L. , Alvarez M.
Published: May 2005

Established methods for measuring the incident angle related to XRF when radioisotope annular sources are involved are briefly discussed. As an alternative technique, a direct measurement of the incident angle from the measured spectrum of the Compton scattered energy was developed. Analysing published experimental data, the limit of validity of this new approach is defined and it is established that for the sensitivity determination only the spectral data are required.
Effect of the photon intensity selected at various positions under the photopeak on the mass attenuation coefficient of x‐rays
Authors: Kerur B. R. , Thontadarya S. R. , Hanumaiah B.
Published: May 2005

The variation in the value of the mass attenuation coefficient of x‐rays in aluminium was studied by counting photons under various positions in the photopeak employing a proportional counter spectrometer system with a good geometrical set‐up. The effect of (small angle) scattering was also examined using three different sets of collimators of diameter 9, 6 and 3 mm and employing both a pure x‐ray source (55Fe) and a mixed radiation source (57Co). The μm values obtained at the FWHM position for each set of collimators agree closely with the theoretical values.
Dependence of the accuracy of the results of steel x‐ray fluorescence analysis on the method of considering the variation of α coefficients with sample chemical composition
Authors: Molchanova E. I. , Smagunova A. N. , Gunicheva T. N. , Smagunov A. V.
Published: May 2005

The accuracy of the results of steel x‐ray fluorescence (XRF) analysis using certain computation algorithms, differing in the way in which they consider the dependence of α coefficients on sample composition, was compared by means of the determination of chromium in steel standard samples, the chemical compositions of which represent possible compositional variations of 456 different types of high‐speed, high‐, medium‐ and low‐alloy steels. It is shown that in the XRF analysis of steels, the best accuracy is provided by algorithms in which this dependence is based on real variations in the concentration of interfering elements. Algorithms using constant influence coefficients may also give acceptable accuracy of XRF results provided that more exact calculation of equation parameters, by which the values of reduced element concentrations are obtained, are found. Recommendations for increasing the accuracy of these parameter calculations are given.
Background determination in wavelength‐dispersive electron microprobe analysis: Some difficulties and presentation of a new analytical model
Authors: Fialin Michel
Published: May 2005

A background (BG) model is proposed for the determination of minor and trace element compositions with an electron microprobe (wavelength‐dispersive spectrometry). This model is particularly useful when a major band partially overlaps the peak corresponding to the element of interest. Its relationship is derived from a second‐order polynomial and can be written as Bv = (B1 + B2)/2 + (1 + KBG)(B2 − B1)/4, where B1 and B2 represent BG measurements to be performed on two symmetrical positions with respect to the analysed peak and KBG is a coefficient to be determined on a standard (BG standard) free from the sought‐for element but containing the overlapping peak. No BG standard with an approaching unknown matrix composition is required. An important feature is the shape of the overlapping band, which should be identical in both standard and unknown (at least within the energy range where measurements are performed). This last point is discussed using the example of elements whose analysed peaks are situated close to the Kβ1, 3 bands of transition metals. The shape of such bands, which are related to valence states in the x‐ray emission processes, depends on the atomic chemical environment. Ti and Cr Kβ1, 3 profiles, emitted from pure metals and some oxides, are usefully compared in this respect. The capabilities of the model were tested on the determination of Mn in Cr‐rich compounds (Cr Kβ1,3 strongly overlaps Mn Kα).
X‐ray K‐absorption edge studies in a‐Ga30Se70 and a‐Ga30Se70 − xInx
Authors: Malik M. Manzar , Nigam A. N. , Husain M.
Published: May 2005

The shift of the K‐absorption edge (ΔEk) was measured in ternary alloys of Ga30Se70‐xInx (x = 0, 5, 10, 15, 20) with respect to the binary Ga30Se70 alloy. It was observed that the K‐edge of selenium shifted progressively towards the lower energy side as the indium concentration increased from 0 to 10 at.%. However, at higher concentrations, the relative shift started to decrease. These results are in accordance with Pauling's concept of electronegativity and indicate that the nature of the bond is iono‐covalent in these glasses, as found in many crystalline solids. The composition dependence of the edge shift is also discussed in terms of the structure of the SeGa system.
Background correction procedure for multi‐channel x‐ray fluorescence spectrometers
Authors: Gunicheva T. N. , Afonin V. P. , Finkelshtein A. L.
Published: May 2005

A background correction procedure is described for multi‐channel x‐ray fluorescence spectrometers/quantometers with spectrometric channels of a fixed type. The background intensities are measured for a special background sample. Background intensities of the unknown sample are calculated from these measurements with the help of s and f corrections, taking account of qualitative and quantitative differences in the spectral composition of the background radiation for both an unknown specimen and the background sample. Determinations of the major elements in rocks on a multi‐channel x‐ray fluorescence quantometer demonstrated the capabilities of this procedure.