ISSN:0049-8246    

DOI:10.1002/xrs.1300130302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe thick‐target yield of characteristic x‐rays from a series of gold–silver binary alloys has been determined experimentally (relative to the yield from the pure elements) under proton bombardment, using proton energies of 1. 5, 2. 0 and 2. 5 MeV. The yield per unit concentration of gold or silver varies with alloy composition because of the progressively varying effects of proton stopping power (specific energy loss) and x‐ray self‐absorption in the target materials. Theoretical yields have been calculated using tabulated data for stopping power and x‐ray absorption. When both of these effects are taken into account, agreement with experiment is satisfactory. These results can be made the basis of stopping power and self‐absorption corrections in proton‐induced x‐ray

ISSN:0049-8246    

DOI:10.1002/xrs.1300130303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractThe backscatter region of an energy‐dispersive x‐ray fluorescence spectrum obtained by radioisotope photon excitation of a homogeneous, multi‐element sample of any thickness is considered to be made up of a linear summation of several backscatter response spectra, each due to a constituent in the sample. A Monte Carlo computer program already developed for pure samples has been modified to generate these spectra and the results are compared with real spectra. The characteristic data used for each constituent in mixture and alloy samples, such as scattering cross‐sections and Compton profiles, are those of pure elements. As for chemical‐compound samples, an effective Compton profile is determined from a calibration graph and is used for all the constituent elements. It is shown that, for samples with unknown weight fractions, it is possible to generate the Ag Kα backscatter peaks dependent on such sample characteristics as density, thickness, approximate total cross‐section determined from another calibration graph at the scattered photon energy and effective Compton profile. The unknown weight fractions for all the constituents, including those with very low atomic numbers, are then calculated by using the computer‐simulated Ag Kα peaks for each constituent and a background spectrum as the standard library spectra of a linear least‐squares program. The advantages and drawbacks of such a qualitative analysis together with future improveme

ISSN:0049-8246    

DOI:10.1002/xrs.1300130304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractA method for spectral background evaluation in x‐ray energy analysis is proposed, based on a simple model of background generation in the detector. This model assumes that photons, of a given energy, interacting with the detector have probabilities of generating background counts within lower energy windows. The usefulness of the method resides in the fact that it allows a background evaluation with different levels of complexity and accuracy. The method also permits accurate background calculation with samples of variable mass and composition, such as biological and environmental material

ISSN:0049-8246    

DOI:10.1002/xrs.1300130305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractA new formalism is proposed to correct with accuracy the matrix effects in x‐ray fluorescence (XRF) analysis. It has been deduced from Sherman's equations and includes a new algorithm between concentration and intensity, theoretically exact, and explicit expressions permitting the calculation of αijand ρijcoefficients that correct for absorption and enhancement effects, respectively. In other words, the concept of correction coefficients is established on a solid theoretical basis. In the second part, it will be shown how to adapt this new formalism to practical situations. From an estimate of composition calculated by the Claisse–Quintin algorithm and an appropriate calibration, the new algorithm is used to refine the estimated composition for greater accuracy. This last approach is equivalent to the ‘fundamental parameters’ method but is presented in a simpler version adaptable to any mini

ISSN:0049-8246    

DOI:10.1002/xrs.1300130306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractIn Part 1, a new formalism was proposed to correct with accuracy the matrix effects in XRF analysis. In this paper it is shown how to adapt this new formalism to practical situations. From an estimate of composition calculated by the Claisse–Quintin algorithm and an appropriate calibration, the new algorithm is used to refine the estimated composition for greater accuracy. This last approach is equivalent to the ‘fundamental parameters’ method but is presented in a simpler version adaptable to any mini‐c

ISSN:0049-8246    

DOI:10.1002/xrs.1300130307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractQualitative microprobe analysis of sodian potassian hydroxonian meta‐autunite failed to reveal any sodium, although nearly 3% was present. Potassium, magnesium and calcium were underestimated to a smaller extent in related natural and synthetic structures. The effect is due to the migration of these interlayer cations from the analysed region—almost instantaneously in the case of sodium—and a consequent decrease in count rates, under the influence of the space‐charge resulting from the incident electron beam. Experiments with the autunites and with a soda‐glass subjected to various coating treatments showed that the effect of charging can be dramatic. Such charging also occurs when alkali metals are not present, a fact which has important implications for all microprobe

ISSN:0049-8246    

DOI:10.1002/xrs.1300130308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractApart from their general importance, an accurate definition of spectral intensity distributions from x‐ray tubes is required to support the development of mathematical matrix correction procedures for x‐ray fluorescence analysis. Since a direct measurement is costly, time consuming and occasionally difficult, and a purely theoretical approach is not suitable for current utilization, a simple, readily adaptable calculation procedure is very desirable. Concerning the continuum or white radiation from the x‐ray tube, such an evaluation was worked out by effecting (1) a modification to Kramers' law and (2) a refinement of the absorption correction regarding the absorption by the target itself. The new equation accounts very closely for the best known, carefully measured and corrected experimental distributions by Brownet al. and Loomis and Keith. Extended experiments are required to ensure systematization, and special steps are needed for the treatment of the characteristic radi

ISSN:0049-8246    

DOI:10.1002/xrs.1300130309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

摘要:

AbstractIm 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 h

ISSN:0049-8246    

DOI:10.1002/xrs.1300130310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300130312

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1984

数据来源: WILEY