ISSN:0049-8246    

DOI:10.1002/xrs.1300160102

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

年代:1987

数据来源: WILEY

摘要:

AbstractA radial efficiency correction factor was introduced in the five‐parameter radially dependent model by Cohen to calculate the theoretical efficiency of an Si(Li) detector. The present calculations for the various detectors confirm that the radial dependent factor introduced by Cohen is a geometry‐dependent factor and does not depend on the physical characteristics of the detector. The modified five‐parameter model suggested in this study removes the anomaly between the theoretical calculations and experimental observa

ISSN:0049-8246    

DOI:10.1002/xrs.1300160103

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

年代:1987

数据来源: WILEY

摘要:

AbstractVarious experiments show that low‐energy electron‐induced X‐ray spectrometry (LEEIXS), using a gas discharge tube as an efficient and stable electronic excitation source, represents a powerful new technique in many fields of research related to surface and near‐surface chemical characterization of materials. The instrument is a wavelength‐dispersive X‐ray spectrometer capable of high qualitative or quantitative performances in the soft and ultra‐soft region (λ = 0.3—10 nm). LEEIXS applications given in this paper demonstrate how chemical, electrochemical or physical treatments of various substrates modify the solid sur

ISSN:0049-8246    

DOI:10.1002/xrs.1300160104

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

年代:1987

数据来源: WILEY

摘要:

AbstractUsing Monte Carlo simulations, the mean energies of backscattered electrons for thick targets of aluminium, titanium, iron, molybdenum, tungsten and lead were calculated at various angles of incidence and an incident electron energyE0of 30 keV. The results show that the mean energy ratio,ĒB/E0, of backscattered electrons depends only on the backscattering coefficient, ηB, of the non‐normal electron incidence and varies linearly with it. Analytical expressions are given for calculatingĒB/E0and the backscattering coefficient, which is independent of the backscattering coefficient at normal incid

ISSN:0049-8246    

DOI:10.1002/xrs.1300160105

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

年代:1987

数据来源: WILEY

摘要:

AbstractA 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 a241Am 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 sa

ISSN:0049-8246    

DOI:10.1002/xrs.1300160106

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

年代:1987

数据来源: WILEY

摘要:

AbstractNew 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 val

ISSN:0049-8246    

DOI:10.1002/xrs.1300160107

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

年代:1987

数据来源: WILEY

摘要:

AbstractA standardless method for energy‐dispersive x‐ray microanalysis has been implemented. Pure element intensities were calculated from first principles. The spectrum processing and ZAF correction of the unknown spectra were effected by a modified FRAME‐C program. The replacement of the original constant relative L‐line intensities with Z‐dependent new values according to Schreiber and Wims improved the analytical accuracy of the program. The improvement is demonstrated by a better consistency of the measured and calculated L‐line intensities of pure elements and by the reduction of the RMS error from 15.2% to 8.5%, calculated on the basis of 64 analyses of compound standards measuring K and L line

ISSN:0049-8246    

DOI:10.1002/xrs.1300160108

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

年代:1987

数据来源: WILEY

摘要:

AbstractA method is described for the quantitative analysis of binary mixtures using a simple x‐ray fluorescence technique. It requires neither special preparation of thin samples nor corrections for absorption and enhancement effects. Enhancement effects are avoided using selective excitation and absorption is estimated in terms of intensities of the measured x‐rays. Linear calibrations requiring the use of only two standards are obtained. The application of the method is illustrated with six different binary mixtu

ISSN:0049-8246    

DOI:10.1002/xrs.1300160109

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

年代:1987

数据来源: WILEY

摘要:

AbstractRousseau derived the Claisse—Quintin (C—Q) equation from Sherman's equation. His theoretical description of the influence coefficients used in the C—Q equation is not correct. Also, Rousseau and Claisse as well as Rousseau gave methods for calculating influence coefficients for the C—Q equation but the coefficients listed in their papers are in error. The purpose of this paper is two‐fold: to give a set of equations that contain the correct theoretical description of the influence coefficients, and to give the correct equations for the calculation of these influence coe

ISSN:0049-8246    

DOI:10.1002/xrs.1300160110

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

年代:1987

数据来源: WILEY

摘要:

AbstractThin‐film standards of lead and zinc were prepared by precipitating precise amounts of their insoluble salts directly on to polyamide film substrates for the calibration of the x‐ray spectrometer. Samples of different particle deposition characteristics were then prepared and analysed by XRF, atomic‐absorption and inductively coupled plasma atomic‐emission spectrometry. The optimum sizes of thin‐film specimens were selected to be the same as the area of the specimen plane where the average flux of the primary x‐ray beam is fairly uniform. No significant difference in response of the spectrometer to the Zn Kα and Pb Lβ between the samples and the standards were observed. The correlation of the XRF results with those obtained by the other two methods was found to be 1.008±0.029 for lead and 0.995±0.020 for zinc. The amount of metal present ranged from about 5 to 350 μg for lead and from 10 to

ISSN:0049-8246    

DOI:10.1002/xrs.1300160111

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

年代:1987

数据来源: WILEY