ISSN:0049-8246    

DOI:10.1002/xrs.1300190102

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

年代:1990

数据来源: WILEY

摘要:

AbstractA low dilution fusion (LDF) technique using a 2:1 flux‐to‐sample ratio has been developed for the accurate determination of major, minor and trace elements in rock samples by wavelength‐dispersive x‐ray fluorescence spectrometry (XRFS). The choice of flux, oxidant and the dilution ratio and the application to trace element analysis are discussed. The elimination of particle size effects in the homogeneous glass fusion discs is a major advantage over the use of powder pellets, especially for the determination of elements such as Ba, Cr and the REEs. The fusion technique ensures complete loss of volatiles from the rock samples and provides an accurate estimation of loss on fusion values. The oxidation and retention of sulphur in the discs were also investigated. Instrumental conditions, including corrections for spectral line interferences, are reported for 20 trace elements. The average relative error for the trace elements commonly analysed in rock samples was less than 5% and there was a decrease in sensitivity by about a factor of 2 compared with XRFS determinations on powder pellets. The LDF method has been used for the analysis of geological samples of widely varying and unusual composition, such as lamproites and kimberlites, but is also suitable as a general‐purpose sample preparation

ISSN:0049-8246    

DOI:10.1002/xrs.1300190103

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

年代:1990

数据来源: WILEY

摘要:

AbstractExperimental techniques for eliminating the characteristic x‐rays emitted from impurities in cathode and anode materials in the vicinity of the x‐ray absorption edge were studied with a laboratory EXAFS spectrometer using a rotating anode. Two methods are proposed for this purpose, a current‐control system and a filter method involving the use of a material that selectively absorbs characteristic x‐rays. The former method was applied to the Co, Ni and Zn K absorption spectra and the latter to a Pd K absorption spectrum, and the results were compared with those obtained from conventional measurements. The change in the nearest neighbour structure of Pd in a Pd‐Al2O3catalyst accompanied by oxidation or reduction was clarified by EXAFS and XANES measurements with the use of the filt

ISSN:0049-8246    

DOI:10.1002/xrs.1300190104

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

年代:1990

数据来源: WILEY

摘要:

AbstractA systematic study of Lα/Lβand Lα/Lγx‐ray intensity ratios was undertaken by measuring the characteristic x‐ray intensities in 23 elements over the rangeZ= 55‐80, using a 30 mCi238Pu source of excitation and a high‐resolution Si(Li) detector system coupled to a computer‐controlled multi‐channel analyser. The theoretical predictions due to Scofield were computed for the present energy (weighted average) of 15.28 keV excitation and compared with the experimental values. The experimental values of Lα/Lβand Lα/LγversusZwere fitted to a fourth‐degree polynomial, and most probable values of Lα/Lβand Lα/Lγat eachZwere also

ISSN:0049-8246    

DOI:10.1002/xrs.1300190105

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe shift of the K‐absorption edge (δEk) was measured in Se100‐xInxbinary system where 0 ≤x≤ 30. The K‐edge of Se progressively shifted toward the lower energy side as the In concentration increased from 0 to 15 at.‐%. However, at higher concentrations, the relative shift started to decrease. The results are in accordance with Pauling's concept of electronegativity and indicate that the nature of the bonds is iono‐covalent in these glasses, as found in many crystalline solids. The composition dependence of the edge shift is also discussed in terms of the s

ISSN:0049-8246    

DOI:10.1002/xrs.1300190106

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

年代:1990

数据来源: WILEY

摘要:

AbstractA semi‐empirical approach is described for determining the mass per unit area of a sample being analysed. The method can be used to estimate the concentration of minor and trace elements in matrices containing a substantial amount of light elements. The procedure utilizes the coherently and incoherently scattered radiation induced in the sample by the filtered continuum radiation of a rhodium x‐ray tube. The relationship between the intensity of the scattered radiation per unit mass and the average atomic number of the sample is established via calibration graphs, which can be applied for different x‐ray tube voltages and for different primary beam filters. The overall procedure was validated by the analysis of several geological standards, deposited as thin slurries of unknown thickness either on Mylar foil or on Nuclepore fi

ISSN:0049-8246    

DOI:10.1002/xrs.1300190107

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe diffraction of high‐energy characteristic x‐ray lines, which have relatively large intrinsic widths, by perfect single crystals, which have acceptance angles much less than these line widths, is discussed. Experiments using Bi Kα1, which has an equivalent FWHM of 0.0013°, and an asymmetrically cut Si (111) crystal, having acceptance angles of 0.0002° and 0.0004°, showed that only a small fraction of the total characteristic line was, in fact, diffracted by the

ISSN:0049-8246    

DOI:10.1002/xrs.1300190108

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

年代:1990

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300190109

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

年代:1990

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300190110

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

年代:1990

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300190101

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

年代:1990

数据来源: WILEY