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  • Analytical Chemistry and Spectroscopy  (862)
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  • Wiley-Blackwell  (862)
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  • 1
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Philips PW 1450/00 or /10 automatic hardware-programmed X-ray spectrometer, when used in conjunction with the PW 1466 60 position sample loader, permits measurement of both standard and unknown using the same channel only when the ratio mode is selected. Further, a standard must be measured for every unknown. An electronic modification is described which overcomes both of these restrictions.
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  • 2
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    X-Ray Spectrometry 9 (1980), S. 13-18 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The theoretical relationships between fluorescence intensity and concentration have been used for the calculation of correction constants of the Lachance--Traill and Rasberry--Heinrich equation for systems of solutions. The constants have also been calculated by means of the multivariate least--squares method. Those two alternatives have been tested on systems of Cu--Fe--Zn and Cu--Fe--Zn--Pb in 3.5% aqueous nitric acid and compared with the simple two-variable linear relationship between fluorescence intensity and concentration. The multivariate least--squares alternative gives for the Lachance--Traill method very accurate results (average relative deviation does not exceed 0.18%). In a theoretical discussion, the relationship between optimum sample concentration and solvent correction (enhancement) constant is shown. The optimum conditions for a background reading are also calculated.
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  • 3
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    X-Ray Spectrometry 9 (1980), S. 77-80 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The X-ray K absorption edges of Co in some 1,10 phenanthroline-based complexes of cobalt have been recorded. The results have been discussed qualitatively in terms of the effective nuclear charge on the central metal atom and the nature of the ligand.
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  • 4
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    X-Ray Spectrometry 9 (1980), S. 95-95 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 5
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    X-Ray Spectrometry 9 (1980), S. 96-100 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The use of the multiple linear regression program for the derivation of influence coefficients destroys the data bank in the Philips PW 1450/10 spectrometer computer and interrupts analysis. Consideration of the basis of α-coefficients as applied to relatively dilute solutions leads to methods of avoiding the use of this program. Linear regression involving a single independent variable and simple algebraic expressions can be used to derive the coefficients. The requirements for converting α-coefficients applicable to one solvent for use in a different solvent are described.
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  • 6
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Fifty pairs of window/non-window glasses, the samples in each pair being matched in refractive index to the fourth decimal place, have been analysed using energy-dispersive X-ray fluorescence spectrometry. The spectra, from 200μg fragments, were compared using a computer based multi-dimensional data processing system. Forty-three pairs of glasses were readily discriminated and forty-nine pairs showed significant differences at about the 5% level. The spectral data for the 100 glass samples were then examined graphically for trends in the elemental levels between the window and non-window glasses. This led to the construction of two linear combinations, namely the peak area ratio (to calcium) of iron with that of magnesium and the peak area of arsenic with refractive index. When plotted against each other these linear combinations and a selection rule allowed 95% of the glasses to be correctly classified.
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  • 7
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    X-Ray Spectrometry 9 (1980), S. 134-137 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Description / Table of Contents: A method for quantitative microprobe analyses of geological samples (silicates and carbonates) is described. In the case of silicates for total analysis the need is to detect simultaneously more than 10 chemical main- and minor-constituents. For this purpose two experimental possibilities are available: (a) automatic control of the crystal scanners (sequence control); (b) combination WDS/EDS (wavelength-dispersive and energy-dispersive system). These two possibilities are discussed. Technical notes of the equipment and the analytical method are described in detail. High analytical precision can be obtained.
    Notes: Es wird eine quantitative Analysenmethode für geologische Proben (Silikate and Karbonate) mittels Röntgenmikrosonde beschrieben. Im Falle von Silikaten sind fur eine Totalanalyse mehr als 10 chemische Elemente simultan zu erfassen (Haupt-und Nebenelemente). Zwei experimentelle Moglichkeiten sind realisierbar: (a) Automatischer Sequenzbetrieb mittels Kristallspekrometern; (b) Kombination WDS/EDS (wellenlangendispersives und energiedispersives System). Diese beiden Möglichkeiten werden diskutiert. Technische Angaben und apparativer Aufwand werden beschrieben. Es wird dargelegt, auf welche Weise eine hohe analytische Genauigkeit erreicht werden kann.
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  • 8
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    X-Ray Spectrometry 9 (1980), S. 143-145 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The spectral photon distribution from X-ray tubes operated at constant potential is compared to the distribution resulting from self rectification circuits. Kramers' equation is modified by calculating the average values of the photon flux during one period of voltage fluctuation and the results are used to transform Gilfrich and Birks' experimental tube spectra to those expected from a half-wave rectification circuit. The effect of using both constant potential and sine wave potential, as well as constant potential with overlaid sine wave ripple, is discussed. Results are shown by using experimental data from Ag-Au-Cu alloys and ‘no standard’ methods (data evaluation without reference specimens).
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  • 9
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    X-Ray Spectrometry 9 (1980), S. 153-153 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 10
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    X-Ray Spectrometry 9 (1980), S. 163-169 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The qualitative and quantitative composition of technical aluminium phosphide was studied employing X-ray electron spectrometry, X-ray fluorescence analysis and X-ray diffractometry as well as gravimetric and gas volumetric methods. In addition to aluminium phosphide, AIN (8%), Al(1%) and Al(OH)3 (10%) were found. Al(OH)3 is produced by the reaction of AlP with H2O. Models describing this reaction in humid air and allowing for quantitative analysis are presented.
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  • 11
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    X-Ray Spectrometry 9 (1980), S. 146-149 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Theory and experimental results from X-ray fluorescence analysis without standards are presented. The composition of an unknown specimen is calculated from its count rates without the use of standard specimens. A fast algorithm employing linear approximation techniques uses these normalized count rates as start values for the concentrations and delivers final results usually after the second or third iteration. Accuracy is typically around 10% relative and can be improved by system calibration with standards of arbitrary composition.
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  • 12
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    X-Ray Spectrometry 9 (1980), S. 150-152 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The construction of a demountable X-Ray tube with focal spot scanning intended for operation as an X-ray source in scanning X-ray microscopes is described.
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  • 13
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    X-Ray Spectrometry 9 (1980), S. 206-211 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Multielement thin film standards are made by mixing a solution of different elements and a radioactive tracer (24Na) with the water soluble polymer mehtylcellulose. A film is produced by spreading the liquid mixture evenly on glass plates and letting it dry. Standards of the desired size and shape are punched out. The concentrations of the elements are calculated from the tracer activity. Ten sets of standards containing the elements Na, Mg, Al, Si, P, S, Cl, K, Cs, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Ag, Cd, Sn, Sb, Ba and Pb in different groupings have been prepared. Homogeneity and accuracy oof the standards are extensively discussed. The accuracy is also estimated by the alalysis of the standards using several techniques. The precision of the analysis factors derived from the standards is better than 1-2%, while the accuracy for the elements Al, Cl, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Br, Sb, Ba and Pb is found to be better than 5%.
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  • 14
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    X-Ray Spectrometry 10 (1981), S. 2-7 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Description / Table of Contents: It is shown that the simple models described in literature concerning X-ray analysis are not sufficient to correct the influence of the particle size especially for elements of low atomic numbers (≤ 20) in pressed powder samples. On the basis of proposals for an empirical correction it is possible to analyse single-phase systems with high precision independent of a model and without knowing the average particle size of the examined materials. The considerations necessary for the determination of element concentrations are used to explain the experimental results for a glass powder.
    Notes: Es wird gezeigt, daß die in der Literatur beschriebenen einfachen Modellezur Korrektur des Korngrößeneinflusses für die quantitative Röntgenfluoreszenzanalyse von Elementen mit niedriger Ordnungszahl (≤ 20) in gepreßten Pulverproben nicht ausreichen. Auf der Basis eines empirischen Korrekturvorschlages ist es jedoch möglich, ein mit einem Bindemittel verpreßtes Pulver ohne Kenntnis seiner mittleren Korngröße mit einer für die Praxis ausreichenden Genauigkeit zu analysieren. Es werden die zur Analysenberechnung notwendigen Voraussetzungen beschrieben und die verwendeten mathematischen Formeln am Beispiel eines Glaspulvers erläutert.
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  • 15
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    X-Ray Spectrometry 10 (1981), S. 25-27 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The X-ray K absorption edges of cobalt in some complexes with nitrogen based ligands [α-Co(py)2Cl2, Co(py)2Br2, Co(bipy)Br2 and Co(phen)Br2] have been recorded using a 40 cm bent crystal spectrogrph. The absorption edge shift and edge width have been discussed in terms of effective nuclear charge, molecular symmetry and the nature of the ligand. The radii of the first coordination sphere have been calculated using Levy's method and a correlation suggested.
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  • 16
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    X-Ray Spectrometry 9 (1980), S. 110-118 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The ways in which the usefulness of the electron probe X-ray microanalyser is extended by computer control and the demands imposed on the computer operating system by a general purpose electron probe are discussed. Three main modes of operation are identified and a flexible operating system to meet the main requirements for these modes is described. Examples of the use of the system are given with particular emphasis on two applications which could not be tackled easily with a manually operated system: composition surveys over large areas of the sample and digital mapping techniques.
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  • 17
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    X-Ray Spectrometry 9 (1980), S. 126-133 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A detailed study of energy-dispersive X-ray spectra is undertaken. Considerable attention is given to a method for a systematic and accurate description of the K and L spectra; a digital correction for the peak profile is evaluated. The following second order effects and spectral artefacts are investigated: radiative Auger transitions, spectral background components, Raman scattering of X-rays, silicon escape, fluorescence of the detector materials, and sum peaks.
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  • 18
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    X-Ray Spectrometry 9 (1980), S. 138-142 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Small amounts of particulate matter electrochemically extrated from super-alloys were accurately analysed by X-ray fluorescence spectrometry with pure element bulk standards. The extracts are less than a few hundred micrograms per square centimeter and are not homogeneous. They are approximated by a thin film on a filter substrate. The penetration of the particulates into the membrane filter on which they are mounted is negligible and no absorption correction for the filter is required. The spectral distribution of the X-ray source used in the calculation was obtained from Kramer's formula with self-absorption correction for the continuum and from measurements of the characteristic line. The intensity-concentration algorithm is based on the fundamental parameter method; the calculation is simplified because no matrix correction is required if the relative intensities are less than or equal to 0.04. The method gives excellent results in chemical analyses.
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  • 19
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    X-Ray Spectrometry 9 (1980) 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
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  • 20
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    X-Ray Spectrometry 9 (1980), S. 159-162 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The emission intensities of K X-rays from a number of activation products have been calculated from the known absolute γ intensities, K capture data and internal conversion coefficients of the radionuclides and the fluorescence yields of the daughter products. The calculated X-ray intensities of a few isotopes are compared with those experimentally reported. The X-ray spectrometry of activation products could usefully supplement the γ-ray spectrometry in the instrumental neutron activation analysis and in such cases the data presented here will be of value.
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  • 21
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    X-Ray Spectrometry 9 (1980), S. 184-188 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The paper reviews recent developments in energy-dispersive X-ray detectors and attempts to assess their relevance to industrial process control requirements.
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  • 22
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    X-Ray Spectrometry 10 (1981), S. 85-90 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A systematic investigation of the chemical effects on the calcium X-ray K emission spectra from 32 chemical compounds was carried out using a two-crystal X-ray spectrometer. The observed chemical shifts of the Ca Kα1,2, Kα3,4, Kβ1,3 and Kβ5 lines relative to the respective lines from CaF2 varied in the range +0.06 to +0.30, +0.09 to +0.32, -0.06 and +1.1 to +3.2eV, respectively. A certain dependence on the nature of surrounding groups was found in these shifts. The profile changes in the Ca Kβ5 and Kβ5′ bands from all compounds were discussed by subdividing them roughly into three types, depending upon their characteristic features.
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  • 23
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    X-Ray Spectrometry 10 (1981), S. 126-127 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The evaluation of the true chemical composition of multicomponent alloys by electron probe microanalyser requires the application of several correction factors, viz. atomic number, absorption and fluorescence corrections. Calculation of these factors is dependent upon a set of empirical correlations and needs the use of a computer. An alternative simple procedure of converting raw data into true composition using constants A is presented here. The paper describes the evaluation of these A constants, by rewriting the Ziebold-Ogilivie relation in the form: k/C = A + (1- A)k, and their use in computing true compositions.
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  • 24
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An X-ray flourescence method is described for the direct determination, without pretreatment, of up to 55 trace elements in coal and coal-derived materials. A single assay specimen is prepared by blending finely crushed sample with a binder and briquetting. Calibration is effected by a suite of synthetic calibration standards prepared from spectrographically pure materials blended into graphite. Variations in ash and sulphur content required matrix absorption corrections to analyte and background intensities, which were achieved by use of relationships with the measured Compton scattered radiation. Prior knowledge of or assumptions concerning the composition of the coal are not required. Accurate results are presented for three NBS coal standard reference materials. Certain elements (including TI, Hg, Te, In, Cd, Ag and most rare earths) are normally present in coal at levels below the detection capability of the described method and require quantification by alternative techniques.
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  • 25
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    X-Ray Spectrometry 10 (1981), S. 153-153 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 26
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    X-Ray Spectrometry 10 (1981), S. 168-170 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Si(Li) detector efficieneres are measured up to 100 keV photon energy in typical X-ray fluorescence geometries using 55Fe, 109Cd, 57Co and 241Am annular sources. The targets are common chemical compounds. The photopeak yield is normalized by the use of a bare CaF2(Eu) scintillator which is free of dead layer. The scintillator response is corrected for escape peak losses. The presented method permits the detection of long term changes in detector response. Discrepancies are found in published nominal detector thicknesses.
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  • 27
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    X-Ray Spectrometry 10 (1981), S. 187-192 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We review the maximum a posteriori formalism and apply the technique to the deconvolution problem of energy-dispsersive X-ray fluorescence spectra. An exact closed-from expression for the a priori probability density is derived from physical considerations. A single Cu—Zn spectrum is taken to illustrate the effects of various assumed forms for the restored spectrum probability distributions. Our best results follow from calculations that involve a self-consistency condition. These restorations are contained within the set of maximum likelihood solutions.
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  • 28
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    X-Ray Spectrometry 10 (1981), S. 203-205 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The double line Bragg reflection technique allows phase transition studies with a time resolution of 0.2 s. The Kα and Kβ emission lines from the X-ray tube are recorded simultaneously in an energy-dispersive detector system. Both lines satisfy Bragg's equation for a different phase in the specimen. The latitude of parameter variations and the probability for the required parameter match are discussed on the basis of a specimen transparency model.
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  • 29
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    X-Ray Spectrometry 10 (1981), S. viii 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 30
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    X-Ray Spectrometry 11 (1982) 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 31
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    X-Ray Spectrometry 11 (1982), S. 2-7 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A simple scheme is described whereby x-ray absorption spectra, including the very strong rapidly varying structure near an absorption edge, may be calculated using only a short program and small amounts of computer time. The analysis also provides general rules for the existence of strong structures at the edge. The scheme can describe any neutral absorbing atom (or, with a little modification, ion) and includes the effect of the core hole when necessary. Fits to experiment show good agreement near absorption edges, with somewhat poorer agreement far from the edge. The method is of use in obtaining absorption spectra for use in crystal spectrometers for x-ray mirror calculations where a knowledge of the fine detail of the absorption is not necessary, but an accurate reproduction of the major structure near the edge is.
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  • 32
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    X-Ray Spectrometry 11 (1982), S. 19-24 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Phase transformation studies as well as the determination of linear expansion coefficients are used to show characteristics, accuracy and methods of data evaluation in energy dispersive x-ray diffractometry. A high temperature chamber was modified to withstand temperatures up to 2300°C with fixed angle geometry. Observation of phase transformations in time frames of 10s was possible. In addition, error analyses are made and a method of comparing intensities from angular dispersion to energy dispersive lines is presented.
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  • 33
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    X-Ray Spectrometry 11 (1982), S. 41-41 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 34
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    X-Ray Spectrometry 11 (1982), S. 46-50 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In the X-ray fluorescence analysis of steels, a correction method is usually used so as to eliminate interfering spectrum overlap and absorption-enhancement effects. In correcting the former, the intensity correction method, by which measured x-ray intensity is corrected, is widely used. In the JIS method of x-ray fluorescence analysis of steels, however, the measured x-ray intensity is first converted into a tentative analytical value, and this value is then corrected for absorption-enhancement effects and finally for interfering spectrum overlap. In this report, a detailed comparison of both methods is made, and the characteristics of the JIS method are discussed.
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    X-Ray Spectrometry 11 (1982), S. 79-82 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Description / Table of Contents: The L x-ray spectrum of Np following α-decay of 241Am was carefully reinvestigated by using HPGe detectors. Energy values of major lines are in good agreement with data deduced from Bearden's work, except for Lα1 and Lβ2,15 which exceed theoretical values by 8 and 22 eV, respectively. Intensities of different components agree well with previous experimental work, and β9, β10, γ11, γ13, t and s lines were found for the first time for Np (Z = 93). L subshell probability ratios are consistent with the Hartree-Fock-Slater calculations of Scofield.
    Notes: Le spectre xL du Np accompagnant la désintégration de 241Am a été soigneusement examiné avec des détecteurs HPGe. Les valeurs des énergies des raies principales sont en bon accord avec les résultats déduits du travail de Bearden, sauf pour les raies Lα1 et Lβ2,15 qui dépassent les valeurs théoriques de 8 et 22 eV respectivement. Les intensités des différentes raies s'accordent bien avec les résultats antérieurs; les raies β9, β10, γ11, γ13, t et s sont caractérisées pour la première fois dans le Np (Z = 93). Les rapports de probabilité dans les sous-couches L sont cohérents avec les calculs Hartree-Fock-Slater de Scofield.
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    X-Ray Spectrometry 11 (1982), S. ix 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    X-Ray Spectrometry 11 (1982), S. ix 
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    Notes: A method of correction for the particle-size effect in the x-ray fluorescence analysis of thin and monolayer samples is proposed. The method consists of the measurement of characteristic x-rays excited by x or γ radiation of two different energies. A concept of a substitute radiometric particle diameter instead of the particle-size distribution has been introduced in order introduced in order to enable a practical application of the proposed method. The particle-size correction factors have been obtained theoretically and experimentally for iron oxide (Fe3O4), calcium sulphate (CaSO4) and copper sulphide (Cu2S) with various particle-size distributions. The application limits of the proposed method have been discussed.
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    X-Ray Spectrometry 11 (1982), S. 144-148 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A simple semi-empirical procedure for the determination of elemental concentration in light element matrices is proposed. The method consists of taking x-ray fluorescence spectral measurements at several orientations of the thick planar samples with a standard x-ray fluorescence set-up consisting of a low power x-ray tube and a Si(Li) x-ray spectrometer. The measured intensities are then extrapolated to zero effective thickness for the fluorescent x-rays. In the following we have carried out the extrapolation procedure for the ratios of the Compton scattered Mo Kα x-rays to the fluorescent x-rays which provides the direct determination of the elements in p.p.m. units with respect to the light matrix.
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    X-Ray Spectrometry 11 (1982), S. viii 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    X-Ray Spectrometry 11 (1982), S. 154-155 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Compton scattering technique for rapid determination of ash content in coal has been extended to coke samples. Some improvements in respect of the sample preparation and possible line overlap and background have been incorporated. A modified regression equation used in this work to compute the x-ray data is found to yield good results.
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    X-Ray Spectrometry 11 (1982), S. vi 
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    X-Ray Spectrometry 12 (1983), S. 50-50 
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    Notes: A dependence of the observed Kβ2/Kβ1,3 intensity ratios of As, Se and Br on their concentrations in measured samples was found in a study of the use of these ratios in chemical state analysis. This paper includes the experiments and discussion on this concentration effect, which is caused by the large difference between the self-absorption coefficients of each element for its Kβ2 and Kβ1,3 radiations. An x-ray spectrometer was used for the measurements of the intensity ratios and absorption coefficients. Since the Kβ2 radiation of each element has a wavelength shorter than the Kβ1,3 radiation and longer than the K absorption edge, the self-adsorption coefficient of the Kβ2 radiation was presupposed to be smaller than that of the Kβ1,3 radiation. The results of experiments, however, were contrary to the supposition. The observed self-absorption coefficients of these elements for their Kβ2 radiations were 1.4-2.2 times those of their Kβ1,3 radiations, depending on the chemical states of the elements as absorbers or x-ray emitters. These values gave a solution to the concentration effect. The correction of the effect allows the inherent intensity ratios to be determined which may then be used for chemical state analysis.
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    X-Ray Spectrometry 11 (1982) 
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    X-Ray Spectrometry 12 (1983), S. vii 
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    Notes: The linear relationship between the reciprocal of analyte-line intensity, and the reciprocal of concentration has been applied to the determination of ten major and minor elements in silicate rocks and minerals. The analyses were carried out on fused specimens of 11 rock standards, with and without added La2O3, and with and without added NaNO3. The method requires no absorption matrix effect corrections, and is ideally suited to the analysis of geological materials with a wide range of chemical composition. It clearly has the advantage of simplicity and speed, and can be applied to the analysis of samples when suitable standards are not available. The results obtained in all cases are in excellent agreement with the literature. However, the discs with La2O3 added yield results with better precision and accuracy than do those without La2O3. Na2O is normally determined on separately prepared rock powder pellets, but can be satisfactorily analysed by this method, using the La2O3 added discs, together with all of the other major and minor elements. Na2O analyses are more readily obtained using discs without added NaNO3. We, therefore, recommend that the analysis of geological materials be carried out on fused glass discs with La2O3 added and without NaNO3.
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    X-Ray Spectrometry 12 (1983), S. viii 
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    X-Ray Spectrometry 12 (1983), S. 97-105 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: 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.
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    X-Ray Spectrometry 12 (1983), S. 118-120 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: The analysis of various elements in coal has become important as coal utilization increases. The application of x-ray fluorescence (XRF) to this type of analysis is complicated by matrix-correction needs and lack of matrix-matched standards. The application of fundamental parameter mathematical corrections using easily obtainable doped graphite standards is evaluated.
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    X-Ray Spectrometry 12 (1983), S. 132-132 
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    X-Ray Spectrometry 12 (1983), S. 153-162 
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    Topics: Physics
    Notes: Cross-sections for bremsstrahlung production in thin films may be derived theoretically only if certain approximations are made or if there is recourse to numerical techniques. In this paper, two approximate equations, one based on the Sommerfeld theory and the other on the Bethe-Heitler theory, are assessed for their accuracy in predicting cross-sections differential in photon energy and emergence angle when a thin foil target is bombarded with electrons with energies between 40 and 100 keV. Experimental data are presented from eight different target materials and these are processed initially to make comparisons between experimental and theoretical spectral shapes and subsequently to compare observed and predicted absolute cross-section values. Except for the heaviest target material (Au), the Bethe-Heitler theory provided a satisfactory description of all experimental observations. In contrast, the Sommerfeld theory provided a significantly inferior description of spectral shapes and consistently overestimated absolute cross-sections by 15-20%.
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    X-Ray Spectrometry 12 (1983), S. v 
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    X-Ray Spectrometry 13 (1984), S. 38-43 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: A probability method is used to describe the processes of characteristic x-ray fluorescence excitation and absorption in a heterogeneous monolayer of particles. Based on this the analytical dependence of the characteristic x-ray peak intensity on the sizes and shape of particles, and the distribution of elements among the particles is inferred, for two kinds of spectrum excitation. Theoretical evaluations for applying boundaries of the ‘thin’ homogeneous layer model to a heterogeneous monolayer are given. The elements to be determined in unknown compositions are S, Fe and Pb.
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    X-Ray Spectrometry 13 (1984), S. v 
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    X-Ray Spectrometry 13 (1984), S. 55-59 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: The total cross-sections for ionization of K, L and M shells in various atoms have been calculated using first-order perturbation theory and Hartree-Slater wave functions. For K shells, the hydrogenic wave functions have been used. The systematic changes across the Periodic Table are discussed and the results of a Bethe parametrization are also given.
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    X-Ray Spectrometry 13 (1984), S. 78-82 
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    Topics: Physics
    Notes: The significance of Auger transitions as spectral components in energy dispersive x-ray fluorescence spectra is demonstrated. As a summary of fundamental studies on radiative Auger effects the calculation of their energies and relative intensities is demonstrated. These theoretical deductions result in a suitable incorporation in least-squares techniques by coupling the Auger transitions to the corresponding photopeak originating from the same type of primary vacancy as a function of energy. The simplifications involved, and the removal of systematic misinterpretations and of high correlations of model parameters, are discussed.
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    X-Ray Spectrometry 13 (1984), S. 126-133 
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    Topics: Physics
    Notes: Qualitative microprobe analysis of sodian potassian hydroxonian meta-autunite failed to reveal any sodium, although nearly 3% was present. Potassium, magnesium and calcium were underestimated to a smaller extent in related natural and synthetic structures. The effect is due to the migration of these interlayer cations from the analysed region - almost instantaneously in the case of sodium - and a consequent decrease in count rates, under the influence of the space-charge resulting from the incident electron beam. Experiments with the autunites and with a soda-glass subjected to various coating treatments showed that the effect of charging can be dramatic. Such charging also occurs when alkali metals are not present, a fact which has important implications for all microprobe analyses.
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    X-Ray Spectrometry 13 (1984), S. 142-145 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Description / Table of Contents: In a geochemical exploration project, about 25 000 stream-sediment samples have been analysed. In a new multi-element technique, 36 elements have been determined by a combination of various methods. Optical spectroscopy with are and ICP excitation and wavelength- and energy-dispersive XRFS were used. An XRFS method is presented which allows the analysis of the fraction with particle diameter 〈 0. 18 mm for up to 30 elements with high precision over a large matrix range. The basic idea is to use a large number of reference samples with very different compositions for the calculation of the calibration line.
    Notes: Im Rahmen des österreichischen Rohstoff-Forschungsprojektes Geochemische Basisuntersuchung von Bach- und Flußsedimenten wurden mehr als 25 000 Proben einer Multielementanalytik auf 36 Elemente unterzogen. Neben optischer Spektroskopie mit Kohlebogen- und induktiv gekoppelter Plasmaanregung gelgangten wellenlangen- und energie-dispersive XRFS zum Einsatz. Es wird ein Verfahren beschrieben, das es ermoglicht, die Analyse der Fraktion mit einem Korndurchmesser 〈0.18 mm auf bis zu 30 Elemente rnit hoher Genauigkeit bei einer breiten Streuung des Matrixbereiches durchzufiihren. Der Grundgedanke dabei ist, eine große Zahl von gut analysierten Referenzproben verschiedenster Zusammensetzung fiir die Eichung heranzuziehen.
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    X-Ray Spectrometry 13 (1984), S. 44-45 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: 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.
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    X-Ray Spectrometry 9 (1980), S. 5-7 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: The problem of estimating the chemical composition of small particles of a phase in a matrix of another occurs in a number of fields. The introduction of electron beam microanalytical techniques has made it possible to analyse a volume of 10μm3. In spite of this advancement the chemical composition of the particles themselves is difficult to determine. This difficulty arises from uncertainty as to the full containment of the analysed volume by the particle being analysed. In this paper a statistical approach to establish the chemical composition of the particles themselves has been proposed. This approach is particularly useful when the particles and the matrix have a common element. Two examples are given, one with components of known compositions and another with a component of an unknown composition.
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    X-Ray Spectrometry 9 (1980), S. 19-24 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: A method is presented for determining the relative amounts of Nb and Ge in thin films of approximately 1 μm thickness which have been deposited onto polycrystalline substrates. Quantitative X-ray fluorescence is employed using an energy-dispersive solid state detector and multichannel analyzer system. The principal problem encountered is one of calibrating the observed Ge/Nb intensity ratios in terms of atomic composition. We have used solution standards for comparison with the spectrum of selected dissolved films. The absolute compositions in the region of 25 atomic percent Ge are believed accurate to ±1 atomic percent absolute.
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    X-Ray Spectrometry 9 (1980), S. 32-35 
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    Notes: A set of most probable Kβ/Kα values estimated on the basis of all available experimental data is presented.
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    X-Ray Spectrometry 9 (1980) 
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    X-Ray Spectrometry 9 (1980), S. 40-47 
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    Topics: Physics
    Notes: We present results of X-ray fluorescence measurements on the Shroud of Turin. Quantitative estimates are given for the observed trace quantities of calcium, iron and strontium, and detection limits are established for other elements of potential interest. The calcium and strontium appear as uniform background distributions. Iron traces are observed in all of the data spectra but their local concentrations vary. Comparisons between image and off-image areas reveal no differences, within the precision limits of the data, that would indicate the presence of pigments or dyes containing high-C elements. In ‘blood’ stain regions the measurements show significantly higher concentrations of iron. However, the data do not allow a unique identification of the stain's origin. Quantitative comparisons are made between the shroud results and similar measurements on whole blood and Fe2O3 stains.
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    X-Ray Spectrometry 9 (1980), S. 52-56 
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    Topics: Physics
    Notes: In X-ray fluorescence analysis the concept of radiometric diameter, d, is often introduced in considerations of the fluorescent intensity from a particulate sample. It represents the mean geometric path of the X-rays through one particle and is usually simply taken to be equal to the volume-to-area ratio of the particle. The effective radiometric path is, however, itself dependent on geometry and absorption effects. Rigorous calculations of the fluorescent intensity from a particle in the π and π/2 geometries were carried out to evaluate the errors involved. It appears that, for π geometry, the discrepancy between these exact results and the intensity calculated via the use of d does not exceed 5.2%. For the π/2 geometry, the errors are much larger and can amount to 50% in realistic cases of X-ray fluorescence analysis. These conclusions are also applicable to monolayers. The effective radiometric diameter approaches d only when absorption effects become negligible, but is smaller in other cases.
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    X-Ray Spectrometry 9 (1980), S. 25-27 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    Topics: Physics
    Notes: A non-linear rise in intensity of copper Kα1 and Kα2 X-ray lines has been observed from certain areas of the polycrystalline copper target of a microfocus tube operated at tube currents between 0.1 and 0.5 mA and a tube potential of 13 kV. Under the same conditions the intensity rise of the bremsstrahlung is found to be linear. A functional relationship between total count and tube current has been obtained.
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    X-Ray Spectrometry 9 (1980), S. 39-39 
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    X-Ray Spectrometry 9 (1980), S. 60-65 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Methods are considered for optimizing a conventional Bragg--Brentano X-ray powder diffractometer for the identification of crystalline phases in airborne particulates deposited on membrane filters. The instrumental parameters investigated include detector stepping increment and scan range, Kβ filtration, and the incident beam divergence slit width. Sample-related factors such as substrate material (cellulose ester, polycarbonate and polytetrafluoroethylene), off-axis displacement of the sample and X-ray induced specimen degradation were also studied. Scan times for sample deposits of several hundred μcm-2 are in the vicinity of 24 h with an 800 W tube. These times may be reduced substantially by one or more of the following modifications: rotating anode or synchrotron radiation source, energy-dispersive diffractometry, and Bragg--Brentano diffractometry with a position-sensitive gas detector.
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    X-Ray Spectrometry 9 (1980), S. 70-76 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A method has been investigated which allows calculations from the X-ray fluorescence spectra of the absorption coefficients at any energy for any sample, without any additional measurement. Use is made of the ratio of the characteristic X-ray signals from a Zr wire positioned in front of the sample and from a Pd foil placed behind the sample, both in a fixed geometry. From the experimentally measured absorption coefficient at the Pd L energy (2.9 keV), the coefficients for higher energies are calculated. By the use of an iterative computer routine in which corrections for the enhancement of the Pd foil by the sample are also included, an accuracy of 2% or better on the absorption coefficient determination can be reached for homogenous samples in one measurement. Grain-size and heterogeneity effects induce inaccuracies on the absorption coefficient determinations which might well reach 20% for particulate samples like intermediate thickness deposits of geological materials. This approach thus has the same limitations as the classical transmission method for such heterogeneous samples.
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    X-Ray Spectrometry 9 (1980), S. 90-94 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In charged particle induced X-ray emission studies, the characteristic X-rays are superimposed on a continuous background of electromagnetic radiation. This background is a significant source of uncertainty when charged particle induced X-ray emission is used for analytical purposes. It is demonstrated that the angular distribution of secondary electron bremsstrahlung exhibits significant structure and may be exploited to improve the detection limits attainable with this method. For low-energy continuum X-rays, good agreement is obtained with predictions of the relativistic retardation model. Deviations at higher photon energies are attributed to Compton scattered γ-rays. Finally, suggestions are made regarding optimum energy and angle selections for direct application of particle induced X-ray emission as an analytical technique, especially when biological samples are investigated.
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  • 72
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    X-Ray Spectrometry 9 (1980), S. 101-109 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A computer control system for an electron probe microanalyser has been designed using CORAL-66, a high level compiler language, for the control program and CAMAC modules for the instrument interface. The consequences of the choices made in the design are discussed. The performance of the system was measured by comparing the results from carrying out typical operations by hand and by computer control. The results showed an improvement in precision for general operation and analysis, a reduction in the time for analysis and an improvement in operator performance from using the control system.
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    X-Ray Spectrometry 9 (1980), S. 123-125 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A simple equation relating the intensity of characteristic X-ray lines to their respective weight fractions has been obtained for a thick sample excited by an isotopic source. It follows from the equation that a single intense line in a standard sample suffices to generate calibration constants over a wide range of elements. Validity of this aproach has been demonstrated by the analysis of a standard soil sample using only the Fe Kα line for calibration. A procedure for correction of peak overlaps has been given using the Kβ/Kα ratios, modified by the matrix effects. The method is very useful for the analysis of soil samples and can be conveniently applied to other matrices.
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    X-Ray Spectrometry 9 (1980), S. 57-59 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: To obtain intense linear polarized monochromatic X-rays a single crystal where Bragg reflection occurs at an angle 2θ=90° is used. A number of suitable crystal materials is listed which fulfil the requirements of the Bragg equation for the wavelengths of standard X-ray tubes and the angular condition. As the first result of a new construction a detection limit of 1 ng Ca was determined using a Cr anode and a Ta single crystal (002) plane as polarizer.
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    X-Ray Spectrometry 9 (1980), S. 66-69 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: This paper shows the employment of five X-ray methods for the investigation of a thickness range of 1 Å to 0.1 mm. The well known techniques (X-ray fluorescence and scanning electron microscopy) are treated, a new method (energy-dispersive X-ray diffraction) is discussed and X-ray photoelectron spectroscopy measurements are essentially improved by a new evaluation method. Low energy electron induced X-ray spectrometry is mentioned. As far as significance of the measured thicknesses is concerned, the range of 10--50 nm deserves special attention.
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    X-Ray Spectrometry 9 (1980) 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    X-Ray Spectrometry 10 (1981), S. 28-30 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An improved version of the LAMA program for the quantitative analysis of composition and mass thickness of thin film materials by X-ray fluorescence (XRF) has been developed. The divergence and slow convergence problems occasionally experienced with the LAMA-1 program have been eliminated by using the linear approximation method and the algorithm of simultaneous refinement of composition and thickness to greatly increase its capability and performance. A study of over a hundred simulated thin films showed that the LAMA-2 program converged much faster than LAMA-1 and gave better accuracy. The efficiency of the program has been improved to the point where it is feasible to operate on a minicomputer.
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    X-Ray Spectrometry 10 (1981), S. iv 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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  • 79
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    X-Ray Spectrometry 10 (1981), S. v 
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    X-Ray Spectrometry 10 (1981), S. v 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    X-Ray Spectrometry 10 (1981), S. 57-60 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A method of absorption correction in X-ray diffraction (XRD) phase analysis, based on measurements of Compton scattering, is described. Compton scattering of Mo Kα was measured and Cu Kα was used for XRD analysis. Under these conditions, the method is valid for phase analysis of silicate and carbonate rocks. Quartz content was determined in 13 samples by the proposed method and the conventional method of internal standard. The two sets of results are in a good agreement.
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    X-Ray Spectrometry 10 (1981), S. 61-63 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The experimental evaluation of the Rhodes-Hunuer model of the particle size effect in X-ray fluorescence analysis of ‘thin’ and monolayer samples is reported. The calculations and experiments were carried out for samples of iron oxide(Fe3O4) and copper sulphide (Cu2S) having particles of one size and a histog am distribution of particle sizes. For iron oxide particles, it was found that sticking causes a significant systematic discrepancy between the experimental results and the Rhodes-Hunter model prediction. For copper sulphide particles the model was applicable.
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    X-Ray Spectrometry 10 (1981), S. 74-77 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Relative X-ray fluorescent intensity data have been generated numerically for binary samples under mono-chromatic excitation in those cases of absorption plus enhancement that are dealt with in this work. These data were fitted to the empirical Rasberry-Heinrich equation, keeping both coefficients different from zero, since from our numerical calculations it is shown that in most cases the best fit is achieved when A ≠ 0. Furthermore, this approach shows that a third coefficient introduced into the empirical equation improves the fitting. The aforementioned results suggest that the empirical equation could be deduced from the theoretical equation of fundamental parameters under suitable approximation. The result is an equation similar to that of Rasberry and Heinrich, from which analytical approximated coefficients are obtained. It is then possible to calculate a calibration curve using fundamental parameters values.
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    X-Ray Spectrometry 9 (1980), S. 195-197 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A first approximation indicates that fundamental alpha coefficients for a given analyte vary as a function of the ratio of their respective atomic number raised to a power. This simple rule applies mainly at the limits (i.e., when the weight fraction of analytei, wi is of the order of 0.0 or 1.0) in cases of absorption and weak enhancement. The relation thus provides a means of generating coefficients for the system i-k from experimental data obtained on system i-j and a means of verifying experimental alphas, since arrays of coefficients must show a high degree of concordance.
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    X-Ray Spectrometry 10 (1981), S. 1-1 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    X-Ray Spectrometry 10 (1981), S. 17-24 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The design of an energy-dispersive spectrometer equipped with a conventional X-ray tube and a secondary target is described. The mechanical construction secures a well defined geometry and a high degree of flexibility. The geometry of the irradiation chamber has allowed the polarizing effect of scattering to be investigated. With emphasis on analysis of infinitely thick biological samples a close approximation to the fundamental parameter method for matrix correction has been studied.
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    X-Ray Spectrometry 10 (1981), S. 12-16 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We have developed a highly versatile, energy-dispersive system for X-ray fluorescence (XRF) analysis. Excitation may be achieved both by a Ag anode tube and by isotopic sources of 241Am or 55Fe. Radiation from the former may be either filtered and collimated, or monochromatized by a pyrolytic graphite cylindrical monochromator with further filtration through Pd foils. The system is currently being used both for quantitative fundamental-parameter (absolute) analysis and for standard-based determinations. A variety of mounts allows quantitative work on solid thick or thin samples, liquids, and specimens evaporated on 6.2 μm thick Mylar. Aside from single-sample operation, a 90 position sample changer allows multi-sample analysis, with great gain in work efficiency. The latter is automatically controlled by a PDP 11/05 computer, which also calculates results from the raw data from a Tracor Northern NS 880 energy-dispersive system. Accuracies for analyses of steels (percent level) are ∼5%, while trace Zr/Hf analysis can be performed with 10-15% error; sensitivity for the latter is 0.4-1.0 ppm.
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    X-Ray Spectrometry 10 (1981), S. 41-45 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Full spectra including both the continuous and characteristic lines from X-ray tubes are evaluated in a simple way. The penetrating depth of an electron in the target of the X-ray tube is determined and the Kramers' spectrum corrected for the effects of absorption. The characteristic lines are evaluated from a relation between direct electron excitation and indirect excitation by continuous X-rays. The calculated spectra from W and Cu X-ray tubes are given and their usefulness is confirmed by analysing some typical samples including Ag/Pd and Cu/Zn alloys and BaO/TiO2 mixed oxides.
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    X-Ray Spectrometry 10 (1981), S. 48-51 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A comparison is made between five acid phthalates and clinochlore as analyzer crystals for oxygen Kα emission. Thallium acid phthalate (TAP) is shown to be superior for quantitative analysis because it has high reflectivity, relatively smaller corrections to reflectivity for anomalous dispersion, relatively low high order reflectivities and relatively low fluorescence background. The interplanar 2d spacing for TAP is 25.7626 ± 0.001 Å and its coefficent of thermal expansion α is 32.7 ± 1 K-1. At the oxygen Kα position its effective 2d spacing is 25.724 Å and the mean reflection coefficient is 2.8 × 10-4 rad. For analysis of chemical state, where higher resolution is often desired to distinguish band shapes and satellites, rubidium acid phthalate (RAP) is the best choice. It has α = 37.0±3 K-1, an effective 2d spacing of 26.083 Å and a mean reflection coefficient of 8.2 × 10-5 rad.
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    X-Ray Spectrometry 10 (1981), S. 54-56 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Samples containing identical or very similar phases and differing in their contents of these can be used for calibration of a quantitative X-ray diffraction analysis without knowing their actual mineralogical composition. The method requires that at least one major peak for each phase is well isolated and that the number of calibration samples is equal to or exceeds the number of phases.
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    X-Ray Spectrometry 10 (1981), S. 69-73 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A simple additive method, based on 55Fe and 109Cd source induced fluorescence in a helium environment, is presented for sulphur and lead determintion in petroleum products. Although the density of the matrix influences the X-ray yields, the similarity of photon attenuation in water and petroleum products can be explotied. It is shown that routine system calibration can be achieved by the use of inorganic chemicals dissolved in water instead of organic additives in products. The low pressure helium flow suppresses the argon X-rays, provides a good background region and increases the detection sensitivity for sulphur.
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    X-Ray Spectrometry 10 (1981), S. iv 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    X-Ray Spectrometry 10 (1981) 
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    X-Ray Spectrometry 10 (1981), S. 109-112 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Different sources of counting loss are described and the relation Rt = Rm exp (Rt τ) is considered valid for most commercial XRF counting devices. Based on a series of Kα/Kβ measurements and an initial estimate of the Rt (Kα)/Rt (Kβ) value, corresponding τ values can be computed. If the chosen Rt (Kα)/Rt (Kβ) value differs from the correct one, the τ values will not be identical. The computer program iterates the Rt (Kα)/Rt (Kβ) value until the τ values have reached a desired level of agreement. The program is given together with a worked example of the calculation.
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    X-Ray Spectrometry 10 (1981), S. 117-125 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An X-ray imaging method based on image reconstruction from projections has been established by analogy to medical computed tomography (CT). Where CT uses transmission, X-ray imaging (X-ray macroscopy, XMA) uses reflection. Using an energy-dispersive Si(Li) detector and performing translation and rotation steps of the sample across the line focused X-ray beam separately and sequentially, X-ray imaging suffers from long data acquisition times (several hours). A position sensitive proportional counter (PSPC) has been used to generate a complete translation profile (projection) simultaneously. The sample is illuminated by an X-ray cone and the reflected fluorescence intensity distribution imaged on to the PSPC by an imaging slit. Scanning movements are reduced to sample rotations; sample translation is not required. Preliminary experiments have shown that data acquisition times are shortened by a factor of ten. An experimental arrangement for fast tomographic imaging, results and some problems arising from using a PSPC are discussed. Finally, a second direct imaging experiment, equivalent to scanning the sample across a point-focused X-ray beam, is introduced.
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    X-Ray Spectrometry 10 (1981), S. 138-146 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: It is shown that the depth distribution of X-ray production in the electron microprobe can be accurately described by a Gaussian modified at the sample surface by a transient. Assuming that the Gaussian is a consequence of the electrons undergoing a random walk in the sample and that the transient corresponds with the change from collimated to random electron trajectories enables theoretical values for the amplitudes and coefficients of the two functions to be predicted. There is excellent agreement between the predicted and the observed values. The Lenard coefficient and the electron range can both be estimated from the coefficient in the Gaussian. It is suggested that for microprobe work, Lenard's law for electron absorption be replaced by this revised law. Both the absorption and atomic number corrections of the traditional ZAF approach are replaced by the new function.
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    X-Ray Spectrometry 10 (1981), S. viii 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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    X-Ray Spectrometry 10 (1981), S. 171-176 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Escape peak and thick target yield formalisms are shown to be equivalent, although experimental results using a practical source-target-detector geometry favor the latter. A bare non-hygroscopic CaF2(Eu) scintillator is used to measure the K X-ray yield from thick targets of pure elements excited by monoenergetic photons. The scintillator is found free of dead layer up to the limit of 0.1 μm: it can thus detect photons above 2 keV energy with intrinsic efficiency approaching 100%.
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    X-Ray Spectrometry 10 (1981), S. 193-195 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: In order to empirically test five mathematical equations of matrix correction, the theoretical X-ray intensities of the ternary system Cr—Fe—Ni were used. The smallest analysis error was obtained from a complicated equation which was derived from theory. Simplification of this equation resulted in the equation developed by Rasberry and Heinrich which proved to be almost as effective and is thus to be preferred in practice because of its simpler structure. A further simplification, dispensing with a special correction for secondary fluorescence, led to a greatly increased analysis error. As expected, using the matrix element intensities instead of their concentrations resulted in larger analysis errors. Special consideration of the secondary fluorescence did not yield a better result. These results agree qualitatively well with the results obtained by Stankiewicz and Sanner which were obtained by means of the analysis of synthetic oxide standards.
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    X-Ray Spectrometry 11 (1982), S. viii 
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    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
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