bluuebunny/crossref_metadata_2025 huggingface dataset:
The surface geometrical structure effect in x‐ray fluorescence analysis of metallic samples
Authors: Stankiewicz Wiesław , Fudal Andrzej , Wójtowicz Mirosława
Published: May 2005

The results of investigations into the effect of geometrical surface structure in x‐ray fluorescence analysis of Cu‐Ni alloy are presented. The experimental materials were samples of spectrometric standard quality, in which surfaces were especially prepared by grinding and polishing. The surface state was estimated qualitatively, using a scanning electron microscope, and quantitatively, using a profilograph, by the determination of the roughness parameters Ra and Rz. The relationships between the roughness parameters and Cu, Ni and Si fluorescent radiation intensities, as well as the scattered radiation from the x‐ray tube anode element were established. The optimum range of the surface state for a given alloy has been defined.
A detailed evaluation of counting losses of detectors in wavelength‐dispersion x‐ray spectroscopy
Authors: Banerjee Prabuddha
Published: May 2005

The exponential equation R0 = R · eR0τdescribes the counting losses in wavelength‐dispersive x‐ray spectroscopic (WDF) detectors up to very high counting rates. The correction error can be considerably lower than 1% for a true counting rate of 7 · 105s−1. The dead time constant τ has however to be determined very accurately for this. Methods of determining τ with the desired accuracy are also described. And finally, a formula for correcting for dead time losses for two detectors in series, where each detector has a different dead time, is deduced and verified by experiment. Here again, one can calculate the true counting rate with an accuracy of 1% at a true counting rate of about 7 · 105 s−1.
X‐ray spectroscopic studies of copper compounds and complexes in aqueous solution and polycrystalline form
Authors: Koul P. N. , Padalia B. D.
Published: May 2005

K‐absorption edge‐shifts of copper in CuCl22H2O CuSo45H2O, Cu(NO3)23H2O, Cu(en)3Cl2, Cu(en)3SO4 and Cu(en)3(NO3)2 in aqueous solutions as well as in polycrystalline form were measured using the x‐ray absorption spectroscopic technique. Effective charge on copper ions are estimated using the method of Gianturco and Coulson. The results of the present study reveal interesting results regarding the nature of chemical bonding. An attempt is made to interpret the results in the light of the available data on these samples.
Comparison of some ambient aerosol samplers in combination with PIXE analysis
Authors: Lannefors H. , Carlsson L.‐E.
Published: May 2005

PIXE (particle induced x‐ray emission) analysis of aerosols has been applied to four different samplers to determine sample thickness corrections, detection limits and required sampling times in different environments. The samplers (two total filter samplers, a two stage filter sampler and a cascade impactor) were used with filters made by Ghia, Millipore, Nucleopore and backings of polystyrene film, respectively. The calculations were based on the accumulation mode aerosol (particles in the 0.05–2μm diameter range) composition. Sampling times (resulting in detection limits 10 times lower than assumed aerosol concentrations) ranged from a quarter of an hour in urban, to a quarter of a day in rural and to two weeks in remote environments. These sampling times are calculated with the requirement that at least one element representing each of the following sources was detected: fossil fuel combustion (S, V and Ni), leaded petrol combustion (Br and Pb) and general industrial activities (Cr, Cu and Zn). Generally the two stage filter sampler employed with Nuclepore filters yielded the highest time resolution when specific flow rate, thickness and substrate impurities were taken into consideration. Thickness corrections based on a proton energy of 2.55 MeV and typical ambient urban and rural aerosol matrices show that elements of low atomic number such as P, S and Cl, where the x‐ray self absorption effect is most important, require a 10–20% correction with a uniform deposit thickness of about 0.5 mg cm−2 and a non‐nuniform (conical) deposit thickness of about 1 mg cm−2. For elements of higher atomic number than vanadium (K x‐rays) the proton energy loss correction dominates. Sampling times resulting in the above mentioned deposit thicknesses were shortest for the cascade impactor while the Millipore and Nuclepore filter samplers were least critical in this respect.
The direct addition of Fe‐55 into the sample for low Z elemental analysis by x‐ray emission spectroscopy
Authors: Labrecque J. J. , de Benzo Z. A. , Rosales P. A. , Preiss I. L.
Published: May 2005

A new radioisotope excited x‐ray fluorescence (XRF) technique which employs source‐samples has been applied for the determination of low Z elements in geological materials. The source‐samples is prepared by directly inserting about 100 μCi of the radioisotope (Fe‐55) into about 10–20 mg of the sample in its holder and placing this directly on the face of the detector window. The precision (relative total standard deviation) of this technique for K2O%, CaO% and TiO2% is about 4% and is compared to conventional radioisotope excited XRF. Finally, the accuracy of this technique is shown by the analysis of five geological reference materials as well as compared to conventional radioisotope excited XRF.
K x‐ray production cross‐sections of Ag, Sn and Te by 32–80 MeV 32S ions
Authors: Bǎdicǎ T. , Ciortea C. , Petrovici A. , Popescu I. , Osipenko B. P.
Published: May 2005

K x‐ray production cross‐sections of Ag, Sn and Te by 32‐80 MeV 32S ions have been measured. The dependence of target K x‐ray yields on the target thickness was found to be negligible in the S (64 MeV) + Ag collision system. The experimental data are compared with some theoretical predictions.
Consideration of an enhancement effect simplified expression in limiting cases in x‐ray fluorescence analysis
Authors: Kuczumow Andrzej
Published: May 2005

The problem of a simplified expression for the enhancement term of correction equations in XRF analysis was treated using the example of binaries. Attention was paid to up‐to‐date propositions of a solution to that problem and new cases of solutions were considered. Some common elements of these solutions were found and on the basis of a fundamental expression of enhancement effects a more general equation is given.
Measuring the dead time of an x‐ray spectrometer by means of the first‐ and second‐order reflections method
Authors: Bonetto R. D. , Riveros J. A.
Published: May 2005

The dead time of a Philips PW 1410 x‐ray fluorescence spectrometer with a photon detector has been calculated employing intensities of first‐ and second‐order reflections. The spread of the values obtained can be considered very satisfactory in the light of the experimental difficulties inherent in this method.
A fundamental parameter method for measurement of the thickness of pure element films by an EDX technique with a proportional detector
Authors: Takagi H. , Shima H. , Ui T. , Asada E.
Published: May 2005

Application of the fundamental parameter method to the determination of film thickness by an EDX technique with a proportional detector was performed by considering that x‐rays striking the detector were composed of the following kinds: (1) the analyte line of the film excited directly by the primary beam, (2) the analyte line of the film excited secondarily by scattered or characteristic x‐rays from the substrate and (3) scattered and characteristic x‐rays from the substrate which passed through the film to be analysed. The intensity of all these types were considered theoretically, and the film thickness was evaluated by fitting the theoretical intensity of the x‐rays striking the detector to the experimental intensity, by use of an iteration process. In addition, the accuracy of the theoretical values of intensities excited secondarily was verified by comparison with the experimental values.
Computer method for qualitative wavelength‐dispersive x‐ray fluorescence analysis
Authors: Vila E. , Bermúdez‐Polonio J. , Jiménez‐Seco J. L.
Published: May 2005

A computer method for the qualitative analysis of fluorescence spectra recorded with any analysing crystal and using any wavelength‐dispersive x‐ray spectrometer is described. Originally, the programs are designed for an Olivetti P 6066 computer without being on‐line with the spectrometer. These programs may, of course, also be used with slight modifications with higher capacity and on‐line computers, thus making the analysis easier and faster.
Compton scattering of x‐rays: Some observations
Authors: Pandey H. D.
Published: May 2005

A set of experimental observations pertaining to Compton scattering of low‐energy x‐ray photons by matrices containing very light elements is reported.
Evaluation of interelement coefficients by the fundamental parameter method in alloy analysis by XRF
Authors: Orlić Ivica , Makjanić J. , Valković V.
Published: May 2005

A method for the calculation of interelement ‘empirical’ coefficients through the fundamental parameters method has been developed. The results of standard alloy analyses obtained in this way confirm the validity of this approach.
Zn Kα/Rb Kβ ratio of Ch'ing, Republic and modern Chinese porcelains
Authors: Yap C. T. , Tang S. M.
Published: May 2005

122 pieces of Chinese porcelains from K'ang Hsi to 1982 made in Ching‐te Chen were analysed using energy‐dispersive x‐ray fluorescence with a Cd‐109 exciter. The Zn Kα/RB Kβ ratio was found to be less than about 0.12 ± 0.03 for all pieces made before World War II and greater than about 0.12 ± 0.03 for all pieces made after the War, making it possible to detect modern fake reproductions easily and nondestructively.
Energy dependence of photon‐induced Kα and Kβ x‐ray fluorescence cross‐sections for some elements with 20 ≤ Z ≤ 56
Authors: Garg M. L. , Mehta Devinder , Kumar Sudhir , Mangal P. C. , Trehan P. N.
Published: May 2005

Kα and Kβ x‐ray fluorescence cross‐sections were measured at ten excitation energies ranging from 5.96 to 59.54 keV for elements with 20 ≤ Z ≤ 56 and the experimental results were compared with the theoretical values. Fairly good agreement was observed within the uncertainties of the determinations. This is the first time that measurements have been made for ten elements at a number of excitation energies and Kβ XRF cross‐sections are also reported for the first time.
Shift of the centroid of the Co Kα peak of Co3O4 converted from CoCO3 by various calcination parameters
Authors: Rosales P. A. , Carías O. , Labrecque J. J.
Published: May 2005

The calcination of CoCO3 in air results in Co3O4 with particle sizes depending on the heating temperature: the lower the temperature, the smaller is the particle size. It was previously reported that the centroid of the Co Kα peak shifted greatly (>500 eV) when the product (Co3O4) was formed by different calcination temperatures between 200 and 700°C. In the work, attempts were made to reproduce these results by using not only variable temperature but also variable time, and determined the centroid with a high‐resolution Si(Li) detector rather than a scintillation counter. The results showed the shifts to be about ten times smaller than previously reported. The shift of the Co Kα peak centroid has been estimated to be less than 30 eV.
Particle size effects in the X‐ray fluorescence analysis of monolayer samples
Authors: Krasnopolskaya N. N. , Volkov V. F.
Published: May 2005

A set of particulate monolayer samples with a δ‐distribution of particle sizes has been produced on Lawsan membrane filters by means of a cascade impactor. The accuracy of a proposed equation for characteristic x‐ray intensity from particulate monolayers of various chemical and granular compositions has been experimentally confirmed. x‐ray spectra of Fe and PbTiO3 powders have been examined following excitation by monochromatic photons.
Heterogeneity effects in direct XRF analysis of traces of heavy metals preconcentrated on polyurethane foam sorbents
Authors: Török Szabina , Braun Tibor , Van Dyck Peter , van Grieken René
Published: May 2005

Trace amounts of heavy metals were preconcentrated on discs of polyurethane (PU) foam loaded with ammonium diethyldithiocarbamate (DDTC), to increase the sensitivity of XRF. Since the diameter of the cavities in the open‐cell PU foams reaches 30–300 μm, considerable heterogeneity effects might occur, which could reduce the accuracy of the method. The possible systematic error introduced by considering the sample to be homogeneous is calculated using the Berry et al. model. The calculations show that the underestimation of the absorption correction factor when considering the sample as being homogeneous is less than 2% for high‐Z elements when the sample thickness is at least 2 mm. The detection limits are also around the minima for this thickness.
Portable X‐ray fluorescence analyser with increased precision by using the method of balanced filters
Authors: Vatai E. , Andó L.
Published: May 2005

An increase of an order of magnitude in the precision of the balanced filters method is achieved by using a low‐power x‐ray tube and measuring the ionization current, without increasing the measurement time. A simultaneous change of excitation and detection is essential: the measurement of the ionization current makes possible a dead‐time free detection of the high intensities excited by the x‐ray tube, and leads to a decrease in the statistical error. The standard deviations obtained with a portable analyser utilizing this method in the determination of the Cr and Mn contents of low‐alloy steels in the concentration range 0–1.5% are 0.02 and 0.03%, respectively.
Empirical absorption equations for use in X‐ray spectrometric analysis
Authors: Gerward L.
Published: May 2005

Analytical approximations for mass attenuation coefficients have been derived in an energy range adapted to x‐ray spectrometric analysis (2–40 keV). Approximation parameters have been calculated using a recent compilation of photon interaction cross‐sections.
Sample homogeneity in energy‐dispersive XRF trace metal analysis
Authors: Rastegar B. , Jundt F. , Gallmann A. , Rastegar F. , Leroy M. J. F.
Published: May 2005

The x‐ray fluorescence analysis of trace elements in aqueous solutions requires adequate sample preparation techniques. Aqueous solutions, taken from the environment, often contain chlorides or carbonates, which are likely to produce small crystalline conglomerates in the dried specimen. The use of emulsifiers in the process of specimen preparation was investigated and their advantages demonstrated.
X‐ray K absorption spectra of copper in its soaps and their liquid crystalline solutions in benzene
Authors: Nigam A. N. , Rajput O. P. , Shrivastava B. D.
Published: May 2005

The K absorption edge of copper in myristate, palmitate, stearate and oleate soaps and their benzene solutions have been studied. The solutions show pronounced EXAFS and seem to be liquid crystalline.
A simple absorption correction for electron probe X‐ray microanalysis of bulk samples
Authors: Markowicz A. , Storms H. , van Grieken R.
Published: May 2005

A simple procedure is proposed for the calculation of the absorption correction factor in electron‐probe x‐ray microanalysis. It is based on the concept of an effective depth of x‐ray production, assuming a rectangular depth distribution function for x‐ray generation. This effective x‐ray production depth is expressed as a fraction of the x‐ray excitation depth given by Whelan's expression. Adequate values for this fraction are presented. Two versions are considered. In the first the effective x‐ray production is a function of both the characteristic x‐ray energy and the atomic numbers of the matrix elements, whereas in the second one, which is indicated for routine use, the energy dependence is neglected. Calculations pointed to satisfactory results, even for low x‐ray energies and high overvoltages.
Quantitative electron probe microanalysis of carbon in binary carbides. I—principles and procedures
Authors: Bastin G. F. , Heijligers H. J. M.
Published: May 2005

Introductory investigations performed in order to make quantitative electron‐probe microanalysis of very light elements such as boron, carbon, nitrogen or oxygen possible are described. The practical problems encountered in this kind of work are discussed in detail and, where possible, solutions are proposed. It is shown that with very light elements such as carbon it is no longer permitted to measure x‐ray intensities at the position of the maximum of the emission peak as the shape of the carbon Kα peak is subject to strong alterations, depending on the type of chemical bond involved. As a consequence, integral measurements have to be performed and it is shown that errors of 30–50% can easily be made if this is neglected. The lengthy procedures, connected with integral intensity measurements, can be shortened considerably by the introduction of area/peak factors, which, by definition, represent the ratio between the correct area (integral) and the peak intensity ratio. The accurate determination of such factors for 13 binary carbides is described. This set of factors will permit future measurements simply on the peak; multiplication of the peak intensity ratio by the appropriate area/peak factors will then yield the correct integral intensity ratios.
Energy dependence of the, sensitivity of sequential x‐ray spectrometers obtained from multi‐element standards
Authors: Freiburg C. , Reichert W. , Solomah A. G.
Published: May 2005

The sensitivity of an x‐ray spectrometer as a function of the x‐ray energy is defined as S = I/c = f(E), where S is the sensitivity, I is the count rate per second, c is the concentration and E is the x‐ray energy of the analyte line. Knowledge of its exact shape is needed to calibrate the spectrometer and to analyse minute amounts in different matrices. It can be determined experimentally using multi‐element standards with low concentrations of the standard element, with careful selection of the standard and the matrix compounds. The homogeneous mixtures of powder pellets were obtained by ball‐milling with the addition of lubricating agents. The grain sizes were controlled under a light microscope.

Two empirical equations describing the sensitivity are proposed:
equation image
where S is the sensitivity, A, B1, D and F are numerical coefficients, θ is the Bragg angle of the analysing crystal, E0 is the energy of maximum sensitivity (E0 = 17.6 kV) and the exponent p is equal to 0.5. The ranges of validity of Eqns (1) and (2) are discussed for a PW 1410 (Cr side‐window tube) and an S/MAX (Rh front‐window tube) spectrometer. An application using Eqn (1) is given for the determination of the element concentrations from Nb to Ni in certified soil standards.
Ageing of glass disks. A Monte Carlo simulation of the related XRF intensities
Authors: Helsen J. A. , Vrebos B. A. R.
Published: May 2005

The order of magnitude of change of intensities of Ca and Si Kα and La Lα lines in a homogeneous solid solution with respect to a microsegregated sample is estimated by Monte Carlo simulation. The overall composition of the (hypothetical) melt is Li2CO3La2O3 (19:1) with 5, 10 or 15% of CaSiO3. Calcium metasilicate was assumed to segregate from the flux in particles with radii of 1, 5, 10 or 15 μm. Intensity changes comparable to those observed in real samples are obtained.
The amorphous character and particle size distributions of powders produced with the Micronizing Mill for quantitative x‐ray powder diffractometry
Authors: O'Connor B. H. , Chang W‐J.
Published: May 2005

The rapid rise in the popularity of the McCrone Micronizing Mill for sample preparation in routine quantitative analytical x‐ray powder diffractometry (XRPD) has led to the present examination of material obtained with the device and a comparison with material produced by the widely used Tema Mill. Specimens of α‐quartz, prepared for a range of milling times under wet‐ and dry‐grinding conditions, were assessed according to their particle size distributions and XRPD integrated intensities. Particle size distributions were measured using a sedimentation technique. Changes in XRPD integrated intensity with milling treatment have been used to derive amorphous content indices representing the change in estimated intensity attributed to milling. The results show that the McCrone Mill can produce XRPD specimens of α‐quartz for assay work which adequately satisfy particle size criteria. Powders obtained by wet‐milling with the McCrone device are more acceptable for XRPD work than those prepared by dry‐milling, and both are clearly superior to powders produced with the Tema Mill under the dry‐grinding conditions considered in this study.
Quantitative x‐ray fluorescence analysis. Theory and practice of the fundamental coefficient method
Authors: Broll N.
Published: May 2005

The object of this paper is to outline the principle of the fundamental influence coefficient method and emphasize its utilization for the accurate x‐ray fluorescence analysis of compact or diluted specimens.

For any given composition, effective coefficients, as defined by Tertian's identities, can be derived from the calculation of the theoretical fluorescence intensities, as used in the fundamental parameter approach. The importance of a careful selection of theoretical data is underlined. These include the fundamental parameters, i.e. essentially the mass absorption coefficients and the excitation factors, and the instrumental characteristics, namely the spectral intensity distribution of the x‐ray tube and the geometric factor of the spectrometer. All of these data are still under investigation and the accuracy of their determination is being assessed. The effective coefficients are inserted in a comparison standard algorithm, a practice which compensates for the residual uncertainties affecting some of the parameters. In fact, and in terms of concentration ranges, the compensation limits are fairly large and can be extended, if necessary, by recurrence procedures. A special correction algorithm, similar to the basic one, but based on ‘modified’ coefficients, is used for the analysis of diluted specimens. A suitable computer program and its accessories are defined and their use is illustrated by a variety of practical applications including the analysis of stainless steels, high‐temperature alloys, non‐ferrous alloys (bronzes) and, as an example of fused specimens, cement. The characteristic of the fundamental coefficient method is that it combines the theoretical exactness of the fundamental parameter approach with the flexibility of the usual Lachance‐Traill formulation, thus allowing any given analytical problem, whether complex or comparatively simple, to be studied and solved in agreement with the actual degree of difficulty and the accuracy required.
Optimization of geometry for x‐ray analysis of rare earth materials
Authors: Lal Madan , Choudhury R. K. , Agrawal R. M.
Published: May 2005

A method of sample excitation is proposed for obtaining good sensitivity and detection limits for rare earth elements (57 ≤ Z ≤ 69) by energy‐dispersive X‐ray fluorescence analysis using a 241Am radioisotope source. Detection limits of about 100—300 ng for most of the elements using a thin multi‐element sample on a Mylar backing are obtained for a counting time of 1 h with a 100 mCi source. The configuration employed is a close‐coupled collimated side source geometry in which the sample is mounted at 45° to the plane of the detector. This geometry was found to be superior to the commonly used wide annular geometry in terms of the detection limits obtained for the analysis of rare earth elements. A comparative study of the performance of different source geometries using both Mylar‐ and cellulose‐based samples is described.
Theoretical assessment of the coefficients ϕ(0) and γ0 of the Gaussian ϕ(ρz) curves
Authors: Saa J. H. Tirira , Riveros J. A.
Published: May 2005

New analytical expressions for the surface ionization, ϕ(0), and the amplitude of the ionization distribution, ϕ(ρz), in the surface γ0, are derived which take into account physical reality. Values of these parameters are obtained using these expressions and compared with previous models and experimental determinations. The proposed expressions show very good agreement with measured values.
Die Nutzung externer Linienz‐zu Untergrundverhältnisse in der quantitativen energiedispersiven Elektronenstrahl‐Mikroanalyse. (Use of external peak‐to‐background ratios in quantitative energy‐dispersive electron probe microanalysis)
Authors: Heckel J. , Jugelt P.
Published: May 2005

A method is described for the quantitative analysis of bulk specimens without standards by using external peak‐to‐background ratios in energy‐dispersive electron probe microanalysis. The advantages of this method are discussed in comparison with other correction procedures and the efficiency is demonstrated by means of the quantitative analysis of eight binary specimens and two steel specimens. An algorithm is described for the quantitative analysis of a bulk specimen with a rough surface.
Kβ2/Kβ1,3 X‐ray intensity ratios of arsenic, selenium and bromine in various chemical states (chemical state analyses of As, Se and Br by X‐ray method. 4)
Authors: Iwatsuki Masaaki , Fukasawa Tsutomu
Published: May 2005

A dilution method of correction for a strong self‐absorption effect on the measurements of Kβ2/Kβ1,3 intensity ratios of arsenic, selenium and bromine is described. The intrinsic intensity ratios obtained by the method are given and discussed for these elements in various states in powder and solution samples. The results are as follows: (1) the intensity ratio increases in the order As < Se < Br; (2) any element with a negative oxidation number gives a considerably larger intensity ratio than the same element with a positive or zero oxidation number; (3) the atoms surrounded by stronger electron donors give a larger intensity ratio; (4) a solution sample of a substance gives a larger intensity ratio than its powder sample, except for arsenic compounds; (5) a dilute solution sample below 0.1 M gives a larger intensity ratio than its concentrated solution sample, and its ratio is little affected by coexisting ions.
A new measurement of the Lα1,2 X‐ray emission spectrum of Zn and the K emission bands of Zn and Ga
Authors: Leiro J. A.
Published: May 2005

A measurement of the Lα1,2 X‐ray emission spectrum of Zn is described. The experimental 3d band seems to be slightly narrower than the calculated band provided that the lifetime broadening of the 2p level and the instrumental function are taken into account. The high‐energy satellites of the Zn Lα1,2 line are discussed and the relative intensities of the features considered. Also, the K emission bands of Zn and Ga have been measured. The quadrupole lines have been identified in these spectra and the relative intensities estimated.
Description of low‐energy peak distortion observed in X‐ray spectrometry with Si(Li) detectors
Authors: Heckel J. , Scholz W.
Published: May 2005

A simple model is developed to describe the shape and intensity of the low‐energy peak distortion measured with Si(Li) detectors in X‐RAY SPECTROMETRY. Based on this model, a method is outlined for correcting the distortion channel by channel, which drastically reduces the expense of the deconvolution of the pulse‐height spectra measured in energy‐dispersive X‐ray emission analysis with Si(Li) detectors.
Elemental analysis using electron beam‐induced K X‐rays
Authors: Pape A. , Sens J. C. , Georgiadis A.
Published: May 2005

Representative production cross‐sections for bremsstrahlung, which constitutes an unavoidable spectral background in an X‐ray analysis using electron beam excitation, have been calculated as a function of target and angle for incident electrons in the energy range 0.2—10 MeV. These values, used in conjunction with the corresponding K X‐ray production cross‐sections and non‐fundamental experimental variables particular to each laboratory (detector resolution and ambient background), determine the feasibility of a K X‐ray analysis by direct electron beam excitation, and permit the evaluation of an ideal detection limit.
Optimization of geometry for radioisotope excited X‐ray fluorescence spectrometry
Authors: Dos Santos J. M. F. , Conde C. A. N.
Published: May 2005

The source‐sample‐detector efficiency for the recessed source geometry was evaluated, using Monte Carlo techniques, for a variety of samples and sources and found to be superior to that for other geometries in energy‐dispersive X‐ray fluorescence analysis. The samples considered were those with atomic number in the range 14—44 and the radioactive sources were 55Fe, 244Cm and 109Cd. Efficiencies well above 1% can be achieved for the recessed source geometry and samples with atomic number above 20. The values attainable are around four times larger than those for the annular source geometry.
Uncertainties in mass absorption coefficients in fundamental parameter X‐ray fluorescence analysis
Authors: Vrebos B. A. R. , Pella P. A.
Published: May 2005

Various compilations of mass absorption coefficients are currently used in fundamental parameter computer programs for correction of inter‐element effects in quantitative x‐ray fluorescence analysis. Statistically significant differences in results of analysis were observed for certain sample types when three commonly used compilations were compared, especially when only pure element standards were used for calibration. When type standards combined with a second degree polynomial fit to the standards are used for calibration. When type standards combined with a second degree polynomial fit to the standards are used for calibration, differences between compilations become negligible as determined from the analysis results.
Yield calibration stability of a Si(Li) X‐ray detector system in a PIXE experimental setup over a period of 3 years in the 0.9–9.5 keV photon energy range
Authors: Bombelka E. , Richter F.‐W.
Published: May 2005

Relative experimental detector yields and yield ratios measured on mono‐ and bi‐element standard samples from 1984 to 1987 are presented. Above 3 keV photon energy the yields show good long‐term reproducibility. For example, the spread of 38 single yield measurements on the Au Lα x‐ray line is 1.5%. No temporary changes are observed. In contrast, the measured yields in the photon energy range from 3 keV down to 0.9 keV show distinct temporary changes. At the beginning and end of the measurement period the detector was routinely warmed and re‐pumped in order to ensure a good vacuum in the detector housing. At these times the yields show jumps, which increase with decreasing photon energy up to 20% for Na K x‐rays with 1.041 keV photon energy. Between the detector regenerations the yields show a decreasing tendency with time. This behaviour is attributed to the photon absorption in a varying ice layer on the liquid nitrogen‐cooled Si(Li) detector crystal. After the first regeneration the ice layer thickness was reduced by 0.7 μm. Between the regenerations the ice layer growth rate is estimated to be 0.004 μm per month corresponding to a 0.15 μm ice layer after 35 months. The second regeneration reduced the ice layer by a further 0.22 μm.
K‐shell fluorescence yields of some elements from nuclear decay parameters
Authors: Sidhu N. P. S. , Grewal B. S. , Sahota H. S.
Published: May 2005

The K‐shell fluorescence yields of nine elements with atomic numbers 33, 55, 59, 63, 66, 69, 71, 73 and 80 were measured from a knowledge of nuclear decay parameters. The results are in good agreement with earlier measurements and the fitted values of Bambynek et al. The merits and demerits of the method are discussed.
Quantitative estimates of potassium in whole blood samples from diabetic
Authors: Venkateswara Rao N. , Bhuloka Reddy S. , Narayana D. G. S. , Satyanarayana G. , Sastry D. L.
Published: May 2005

An energy‐dispersive x‐ray spectrometer was used to make a quantitative estimate of potassium in whole blood samples from diabetic subjects and controls. A single standard method employing a fundamental parameter approach was followed for the quantification of potassium x‐ray intensities. The results show that the potassium levels in diabetics are about double those in controls.
Photon‐excited K X‐ray fluorescence cross‐section measurements for some low‐Z‐elements
Authors: Rani Anita , Koshal Rajesh K. , Chaturvedi S. N. , Nath N.
Published: May 2005

X‐ray fluorescence cross‐section for Kα x‐ray lines were measured for the light elements Na, Mg, Al, Si, S, Cl and K relative to Ca at a photon excitation energy of 5.97 keV (Mn K x‐ray). A windowless retractable Kevex Si(Li) detector system having an energy resolution of 146 eV at 6.4 keV was used for the detection of the characteristic K x‐rays. The measurements were performed in a vacuum chamber maintained at a pressure of ca 10−7 Torr using a 55Fe radioactive excitation source and targets of ultra‐pure elements/compounds of the above‐mentioned elements. Cross‐sections were also calculated using photoelectric cross‐sections, fluorescence yields and the fractional x‐ray emission rates. Measured and calculated x‐ray fluorescence cross‐sections agreed within reasonable limits.
Optimization and coupled absorption effects in diamond anvil energy‐dispersive X‐ray diffraction measurements
Authors: Cavaleri Mark E. , Stout James H.
Published: May 2005

Optimization of EDXRD measurements using the diamond anvil high‐pressure cell varies with the particular experimental objectives. In the case of P‐V‐T equation of state studies, the controllable factors are adjusted to optimize the precision and accuracy of the interplanar spacing measurements. The identification of new phases requires the optimization of lattice parameter determinations and the minimization of the effects of thickness on the relative intensities, whereas for reaction rate studies the various factors are adjusted to maximize the absolute intensities of the peaks of interest. In each of these cases there are trade‐offs in the effects of the individual factors that must be made in order to optimize the measurements. Of these factors, the sample absorption is often the most important. For example, profound changes in the relative intensities of diffraction peaks during normal compression studies are caused by the coupled effects of normal sample absorption as the sample thins and the energy dependence of the absorption coefficient. Such changes in relative intensities could be incorrectly attributed to uniaxial stress, residual stress, order‐disorder phenomena or element partitioning. Coupled absorption effects in the presence of a powdered, internal standard also have an important bearing on optimizing the relative proportions of admixed standard and sample.
Method for the determination of Mg and Si contents in aluminium alloys
Authors: Szalóki I.
Published: May 2005

An XRF method was developed for the determination of Mg and Si in aluminium alloys in the range from 0.1 to 0.7 wt%, using a Si(Li) semiconductor detector, a 3H/Ti ring‐shaped radioactive source and a microcomputer. The Mg Kα and Al Kα lines were separated both with the help of library spectra (deconvolution) and with an Se absorption edge filter. The optimum values of the geometrical parameters were determined. Two 3H/Ti sources, covered and not covered with Cr, were tested. The standard deviations of concentrations determined by different methods was compared.
X‐ray K absorption studies on some cobalt thiosemicarbazones
Authors: Shrivastava B. D. , Joshi S. K. , Pandeya K. B.
Published: May 2005

The x‐ray K absorption edges of Co in some thiosemicarbazones were recorded. The results are discussed qualitatively in terms of molecular symmetry and the nature of the ligand. The extended x‐ray absorption fine structure associated with the K absorption edge of cobalt in these thiosemicarbazones was also studied. The average metalligand bond lengths in these complexes were calculated.
New organic crystals as x‐ray monochromators: Triphenylbenzene and thalliúm tartrate
Authors: Charbonnier M. , Romand M. , Grubis B.
Published: May 2005

The usefulness of analysing crystals for x‐ray spectrometry is governed, to a large extent, by their angular dispersion and reflection efficiency, but other features such as crystal fluorescence must also be taken into account. Experimental results are presented that illustrate the performances of two organic crystals: (i) triphenylbenzene, which constitutes an attractive alternative to ammonium dihydrogen phosphate for the determination of magnesium in cements and other calcium‐containing matrices, and (ii) thallium tartrate, which may be recommended for the determination of sodium and possibly magnesium instead of the widely used thallium acid phthalate.
X‐Ray spectrometric determination of minor element contents in stainless steels
Authors: Smagunova A. N. , Molchanova E. I. , Pliner L. N. , Finkelshtein A. L.
Published: May 2005

Models of the dependence of the background intensity on the chemical composition of a specimen for different conditions of analysis are presented. On the basis of these models, a new technique for background correction in the x‐ray spectrometry of homogeneous materials with widely varying composition is suggested. Criteria for evaluation of the necessity for background correction are discussed.
Determination of some trace elements in high‐purity tantalum metal by thin‐film x‐ray fluorescence spectrometry
Authors: Eddy B. T. , Balaes A. M. E.
Published: May 2005

The determination of niobium, molybdenum, tungsten, iron and titanium in tantalum metal is described. After dissolution of the metal and extraction of the tantalum by a chromatographic method using tributyl phosphate, the trace elements are determined on thin‐film samples by x‐ray fluorescence spectrometry. The thin‐film samples are prepared either by spotting the sample solutions directly on to filter‐paper or by coprecipitation with indium. The limits of detection on the thin film are 0.05–0.7 μg, depending on the element being measured.
Evaluation of the armstrong–buseck correction for automated electron probe X‐ray microanalysis of particles
Authors: Storms Hedwig M. , Janssens Koen H. , Török Szabina B. , Van Grieken René E.
Published: May 2005

The Armstrong–Buseck correction for absorption effects in electron probe x‐ray microanalysis of particles considers seven specific particle shapes, and for these geometries exact correction equations are used. This procedure implies that the analyst has to associate the particle to be analysed with a certain particle type; an arbitrary relative thickness is sometimes assumed. A theoretical study was made of this absorption correction as a function of the particle composition, type and thickness for micrometre‐sized particles. It appears that a correct choice of the particle type is critical. However, when the analytical results are normalized to 100%, the differences between the models are much less pronounced, and it is justified to assume a spherical model in all cases.
Quantification of continuous and characteristic tube spectra for fundamental parameter analysis
Authors: Ebel H. , Ebel M. F. , Wernisch J. , Poehn Ch. , Wiederschwinger H.
Published: May 2005

The response of white radiation, expressed as the number of photons per second and energy interval versus energy, is an essential quantity in quantitative x‐ray fluorescence analysis using fundamental parameters. Our investigations gave the best fit of experimental results obtained from ten elements (6 ≤ Z ≤ 82) in the energy range of photons from 3 to 30 keV by the equation
equation image
Contribution due to excitation by scattered photons in measurements of L x‐ray cross‐sections
Authors: Singh Surinder , Mehta Devinder , Kumar Sudhir , Garg M. L. , Singh Nirmal , Mangal P. C. , Trehan P. N.
Published: May 2005

The relative contribution to the production of target L x‐rays by the scattered and K x‐ray parts of excitation spectra from different secondary excitors in annular source geometry is estimated. In contrast to the observations of N. Singh et ul., who made similar measurements using triaxial geometry, we found only a small contribution to the production of L x‐rays by the scattered part of the excitation spectrum in comparison with that by the K x‐ray part. We crosschecked the observations by measuring L x‐ray cross‐sections for five elements, Pr, Nd, Sm, Tb and Yb, at 22.6 keV by two methods: (i) using a 109Cd radioisotope source in the direct excitation mode and (ii) using a secondary excitor of Ag with a 241Am radioisotope source as the primary excitor, in annular source geometry. The results obtained by the two methods are found to be in good agreement.
Semi‐empirical schemes for x‐ray attenuation coefficients in the context of PIXE
Authors: Campbell J. L. , Deforge D.
Published: May 2005

Various semi‐empirical schemes for generating x‐ray attenuation coefficients, μ/ρ, devised primarily for use in electron probe microanalysis, are considered for application in the PIXE analysis of thick specimens where the relevant x‐ray energy region is 1–40 keV. Using selected high‐accuracy experimental data, it is shown that current theoretical values of μ/ρ agree better with the data than do the various schemes. The errors transmitted into PIXE analysis by use of the theoretical values are estimated, and a new parameterization of these values suitable for microcomputer use is justified and tested.
Diffraction of a high‐energy characteristic x‐ray by a perfect crystal
Authors: Short M. A. , Fallon M. R.
Published: May 2005

The diffraction of high‐energy characteristic x‐ray lines, which have relatively large intrinsic widths, by perfect single crystals, which have acceptance angles much less than these line widths, is discussed. Experiments using Bi Kα1, which has an equivalent FWHM of 0.0013°, and an asymmetrically cut Si (111) crystal, having acceptance angles of 0.0002° and 0.0004°, showed that only a small fraction of the total characteristic line was, in fact, diffracted by the crystal.
Holes in the background in XRS
Authors: Self P. G. , Norrish K. , Milnes A. R. , Graham J. , Robinson B.
Published: May 2005

Sharp negative lines have been observed in wavelength‐dispersive (WD) spectra. These ‘holes’ can cause severe errors when analysing for trace elements near the lower levels of detection. The existence of the holes is explained in terms of diffraction from crystailographic planes other than those used in the WD analysis, and an overview is given of the theory necessary to predict the occurrence of the holes with emphasis on LiF(200) analysing crystals.
Analysis of NBS and other reference materials for testing the validity of the α‐parameter correction method in pixe
Authors: Aloupogiannis P. , Robaye G. , Weber G. , Delbrouck‐Habaru J. M. , Roelandts I.
Published: May 2005

A previously described method for correction of PIXE data based on the measurement of proton energy loss, ΔE, and x‐ray transmission factors has been tested on international geological, biological and ore reference materials. After a short review of the sample preparation method and the experimental procedures, the analytical results, precision and accuracy are discussed.
Calculation of x‐ray fluorescence intensities from bulk and multilayer samples
Authors: De Boer D. K. G.
Published: May 2005

Equations are derived for the calculation of x‐ray fluorescence intensities from bulk and multilayer samples. Both intra‐ and interlayer secondary fluorescence intensities are expressed analytically, in terms of the exponential‐integral function. It is shown that calculations are performed much faster with this method than with a previous method using numerical integration. As an illustration, some examples of intensity calculations are given for a thin layer on a substrate.
K x‐ray fluorescence cross‐section measurements of some elements in the energy range 8–47 keV
Authors: Singh Surinder , Rani Rakesh , Mehta Devinder , Singh Nirmal , Mangal P. C. , Trehan P. N.
Published: May 2005

The Kα and Kβ XRF cross‐sections were measured for Sc, Cr, Fe, Ni, Ga, Sr, Nb, Rh, Pd and Te at eight excitation energies ranging from 8 to 47 keV using energy‐dispersive XRF. The Kα and Kβ cross‐sections for all the elements were in general agreement with the theoretical values calculated using photoionization cross‐sections based on Hartree‐Slater potentials and Kβ/Kα intensity ratios based on Hartree‐Fock theory.
Structural studies of glassy semiconducting Se80 − xTe20Inx alloys
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 Se80‐xTe20Inx, where 0 ≤ x ≤ 20. It is observed that the K‐edge of Se shifts progressively towards the lower energy side as the In concentration increases from 0 to 15 at.‐%. However, at higher concentrations, the relative shift starts to decrease. The results are in accordance with the Pauling 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 the Se‐Te system.
Instrumental developments in total reflection x‐ray fluorescence analysis for K‐lines from oxygen to the rare earth elements
Authors: Wobrauschek P. , Kregsamer P. , Streli C. , Aiginger H.
Published: May 2005

Developments in the instrumentation of total reflection x‐ray fluorescence analysis (TXRF) are presented. Different ways of obtaining optimized primary radiation are discussed, and a new double reflector‐collimator is introduced. To increase the number of detectable elements, special devices for low‐Z and high‐Z determinations are presented, in addition to a modular TXRF attachment for versatile applications. Detection limits achieved by various types of excitation conditions are given. TXRF has been shown to be a powerful analytical tool for trace element determinations in various samples.
Study of oxygen peak shifts among some minerals using a tungsten–silicon multilayer pseudo‐crystal
Authors: Liang Long‐Cheng
Published: May 2005

A study of oxygen Kα peak shifts using an electron probe microanalyzer with a W–Si multilayer pseudo‐crystal (2d = 59.8 Å) shows a significant peak shift (0.024–0.043 Å) between simple oxide minerals (e.g. quartz) and minerals containing complex oxygen radicals (e.g. SO, CO and PO). The peak shift of the complex oxygen radicals toward the lower wavelength (or higher energy) side of the simple oxides may indicate a relatively stronger bonding energy inside these radicals than that of the simple cation—oxygen bond. In the direct determination of oxygen, a peak count reduction could occur as a result of this peak shift effect if unsuitable oxygen standards are used.
Measurement of M‐shell x‐ray production cross‐sections using 5.96‐keV photons
Authors: Garg R. R. , Singh S. , Shahi J. S. , Mehta D. , Singh N. , Trehan P. N. , Kumar S. , Garg M. L. , Mangal P. C.
Published: May 2005

M‐shell x‐ray production/fluorescence (M XRF) cross‐sections for five elements with 81 ≤ Z ≤ 92 were measured at 5.96‐keV incident photon energy using thin targets. From the measured M XRF cross‐sections the average M‐shell fluorescence yields were derived. Experimental results for XRF cross‐sections and fluorescence yields were compared with theory. The experimental results were found to be higher than the theoretical values by 10–17%. Further experimental investigations on M XRF cross‐sections for more elements at different excitation energies are required in order to check the validity of the theoretical parameters used to calculate the M XRF cross‐sections.
X‐ray microfluorescence analysis inside and outside the electron microscope
Authors: Pozsgai I.
Published: May 2005

The possibilities of carrying out x‐ray microfluorescence analysis are reviewed. The main approaches are converting the electron optical column of an electron microscope into a transmission x‐ray tube, using microfocusing x‐ray tubes, combining x‐ray tubes with capillary techniques, combining x‐ray tubes with monochromators and applying synchrotron radiation.