ISSN:0049-8246    

DOI:10.1002/xrs.1300160302

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

年代:1987

数据来源: WILEY

摘要:

AbstractAn expression proposed by Lachance is suggested to correct for matrix effects in any system analysed by X‐ray fluorescence. If, for any reason, an analyst does not wish to use the fundamental parameters approach, this expression is a good alternative, yielding accurate results. It is in agreement with the theory and uses influence coefficients calculated from equations containing fundamental parameters only. It is compared with three other expressions correcting for matrix effects and its accuracy is illustrated by calculations for some hypothetical specimen

ISSN:0049-8246    

DOI:10.1002/xrs.1300160303

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

年代:1987

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300160304

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe relationship between the scattering of X‐rays from coal samples and their chemical composition has been investigated using a theoretical model based on the concept of the isolated atom. Model calculations were used to assess the coherent‐to‐incoherent intensity ratio as a means of determining the mineral matter content of coals, and the scope of this application was studied in detail. The procedure was verified theoretically by using the model on a set of well characterized coals. Using a relatively simple calibration procedure the experimentally determined mineral matter agreed with the radiofrequency ash values to within 7.6

ISSN:0049-8246    

DOI:10.1002/xrs.1300160305

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

年代:1987

数据来源: WILEY

摘要:

AbstractNiobium and tantalum have been determined in gelogical samples by X‐ray fluorescence spectrometry without the determination the remaining elements in the sample by applying a suitable modification of the Traill and Lachance equatio

ISSN:0049-8246    

DOI:10.1002/xrs.1300160306

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe widely used formalism for quantitative XRF analysis based on the correction of characteristic line intensity for absorption effects is shown to be inadequate when thick samples with low total mass attenuation coefficients are analysed (biological samples, solutions, etc.). The geometry factor is not a constant function of the collimator's shape and dimensions, but it is found that in an analysed matrix it depends on the line energy and penetration depth. An experimental and a theoretical model for the determination of the geometrical correction are proposed and tested on a set of samples. The concentrations obtained are in excellent agreement with the values expected, whereas the model based on the correction of intensities only for absorption effects gives an error of at least 25% for thick samples.

ISSN:0049-8246    

DOI:10.1002/xrs.1300160307

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

年代:1987

数据来源: WILEY

摘要:

AbstractUsing theoretical expressions derived previously, a set of equations for the calculation of characteristic X‐ray fluorescence spectrometric parameters without standards is derived. All effects due to K series spectra of thejth element which can excite the characteristic fluorescent X‐ray of theith element and all effects due to the instrumentation have been considered. An equation for the calculation of the attenuation factor of the instrument is presented.The results of experiments show that the accuracy of the equations is good, and in their practical application the geometric configuration of the specimen is generally not required. The specimen can be a fragment, piece or powder, etc., without special preparation requireme

ISSN:0049-8246    

DOI:10.1002/xrs.1300160308

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

年代:1987

数据来源: WILEY

摘要:

AbstractBased on the theoretical equations for calculations in X‐ray fluorescence spectrometric analysis without standards in Part 1, a set of equations for practical iteration applied to an iron‐based alloy constituted by ten elements are presented. Some of factors that affect the accuracy of the results are explained and determined. Forty steel alloy specimens were analysed without standards. The results show that the deviations from the results of wet chemical analyses are small, and the geometric configuration of specimen is generally not requi

ISSN:0049-8246    

DOI:10.1002/xrs.1300160309

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe influence of the photons emitted by a241Am XRF excitation source below 59.6 keV on sample fluorescence production has been analysed. A general method for evaluating the contribution of the various lines from the source in specific equipment configurations is presented. The excitation was performed with 23 elemental targets and the measured experimental intensities were fitted by means of a minimization program which takes into account the most important transition groups observed in the spectrum of the excitation source. The program allows for attenuation of excitation and fluoresced photons in the target. Intensity data for the exciting beam were compared with the theoretical intensities of photons from237Np, and it was concluded that these values are compatible with the Am and Al thicknesses of the excitation source. Correction factors considering low‐energy transitions were calculated for several elements for both thick and thin targets. The over‐excitation evaluated forZ= 34 reached values ranging between 180% and 5

ISSN:0049-8246    

DOI:10.1002/xrs.1300160310

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

年代:1987

数据来源: WILEY

摘要:

AbstractAn energy‐dispersive X‐ray fluorescence spectrometer was used to analyse about 100 samples of coal ash. The elemental concentrations were determined using the standardless method and fundamental parameter approach. It was found that the Fe concentration was as high as nearly 30% in some samples. The results suggest that S, Ca, Ti and Fe are the major components that require corrections to be applied owing to X‐ray fluorescence in the back‐scattering techniques used for the determination of the ash fraction

ISSN:0049-8246    

DOI:10.1002/xrs.1300160311

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

年代:1987

数据来源: WILEY