ISSN:0049-8246    

DOI:10.1002/xrs.1300220202

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

年代:1993

数据来源: WILEY

摘要:

AbstractAn experimental comparison is presented between line scanning (coded imaging) and conventional point scanning (direct imaging), based on experience gained with an x‐ray microprobe operated at the Hamburger Synchrotronstrahlungs‐Laboratorium (HASYLAB) at the Deutsches Elektronen‐Synchrotron (DESY). The microprobe uses synchrotron radiation to excite x‐ray fluorescence radiation in the sample, which is detected by a solid‐state detector and analysed for the element composition of the sample. The spatial distribution of elements, even if present only in traces, may be measured on a microscopic scale. Both methods were evaluated with regard to their imaging properties and compared with each other. The line‐scanning technique is shown to have a better signal‐to‐noise ratio, thus achieving a superior image quality. Some sample applications are described f

ISSN:0049-8246    

DOI:10.1002/xrs.1300220203

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

年代:1993

数据来源: WILEY

摘要:

AbstractA previously described low‐dilution fusion technique has been used successfully for the accurate determination of major and minor elements in geological samples. Three methods of calculating appropriate α coefficients have been investigated, namely (1) multiple regression analysis, (2) the Norrish and Hutton method and (3) a computer program, NBSGSC, involving fundamental parameters and the COLA equation. Methods (1) and (2) gave poor results for rock types of widely varying composition. The third method requires that the variation of α coefficients with varying weight fraction of the analyte element be taken into account when calculating such coefficie

ISSN:0049-8246    

DOI:10.1002/xrs.1300220204

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe fundamental parameter method for correction for enhancement and absorption effects in the energy‐dispersive x‐ray fluorescence analysis of intermediate thickness samples using monochromatic excitation was evaluated. A simple means for the calculation of the concentration of an element in an unknown sample without using the iterative approach is proposed. Based on the derived equation, the influence of the higherZsample components and their concentration levels on the enhancement correction factor was examined theoretically and tested experimentally. The concentration of an interfering element was found to have a stronger influence on the enhancement correction factor than the concentration level of the determined element. The method was tested experimentally using various two‐element standard samples and reference materials. The calculated concentrations were in good agreement with the known v

ISSN:0049-8246    

DOI:10.1002/xrs.1300220205

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

年代:1993

数据来源: WILEY

摘要:

AbstractXANES of the nickel systems NiO, LaNiO3, Ni(NO3)2· 6H2O, NiSO4· 6H20, NICO3and Ni3(PO4)2·xH2O were studied using a previously published equation and the nearest neighbour distances were determined and compared with the crystallographic values. The nearest neighbour distance of the system LaNiO3, whose crystallographic value is not available was also determin

ISSN:0049-8246    

DOI:10.1002/xrs.1300220206

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe product of fluorescence yield (ω) and emission probability (Γ), was measured using a method based on the propagation plane inclination. Measurements of the Kα line of elements such as Cr, Fe and Ni on binary samples were carried out to determine the product ωΓ. The results were compared with those reported in well known compilations. The proposed procedure can be considered a new alternative to increase the available set of methods for measuring fundamental parame

ISSN:0049-8246    

DOI:10.1002/xrs.1300220207

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

年代:1993

数据来源: WILEY

摘要:

AbstractA method is presented for the accurate trace determination of tin by wavelength‐dispersive x‐ray fluorescence with a rhodium tube. Because Sn Kα radiation and the incident radiation are very penetrating, sample transparency corrections and special background corrections are required. Explicit equations are derived for transparency corrections with polychromatic incident radiation. The 1/r2dependence of incident intensity strongly affects the corrections. Using a simple, semi‐empirical correction procedure, and synthetic standards ranging from Al2O3to Fe2O3, a calibration graph had a standard error of the estimate of only 1.8%. The detection limit is typically 3.5

ISSN:0049-8246    

DOI:10.1002/xrs.1300220208

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

年代:1993

数据来源: WILEY

摘要:

AbstractA program for the automatic selection of elements found in the spectrum of a sample of unknown composition was developed. Coefficients of presence for elements were determined on the basis of some preliminary assumptions. A practical example is given.

ISSN:0049-8246    

DOI:10.1002/xrs.1300220209

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

年代:1993

数据来源: WILEY

摘要:

AbstractA model for fluorescence radiation line intensity calculations with consideration of x‐ray tube primary beam radiation divergence and actual sample bulk, from which fluorescence radiation is registered at the detector, is proposed. Expressions are provided for commercial instruments having extended and circular sources. These expressions are valid for the short‐wavelength region of the spectrum and for substantial beam divergence, while the commonly used equations are inva

ISSN:0049-8246    

DOI:10.1002/xrs.1300220210

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe x‐ray L3absorption edges of allcis‐1,2,3,4‐cyclopentanetetracarboxylic acid complexes of Gd, Tb, Dy and Ho were recorded with the help of a 400 mm Cauchois‐type bent crystal x‐ray spectrograph. The behaviour of the four lanthanide cations in the environment of the same complexing ligand was investigated. The chemical shifts were correlated with IR studies. Information regarding bonding in these complexes was obtained from the observed chemical shifts. A regular decrease was observed in the average metal—ligand bond distances with increasing atomic number of the metal ion in these complexes and this is interpreted in terms of metal—oxyge

ISSN:0049-8246    

DOI:10.1002/xrs.1300220211

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

年代:1993

数据来源: WILEY