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Hard X‐Ray Spectro Microprobe Analysis of Inhomogeneous Solids: A Case Study. Element Distribution and Speciation in Selected Iron Meteorites

 

作者: Ronald G. Cavell,   Renfei Feng,   Elspeth M. Barnes,   Patricia A. Cavell,   Alistair J. McCready,   M. Adam Webb,  

 

期刊: AIP Conference Proceedings  (AIP Available online 1904)
卷期: Volume 716, issue 1  

页码: 36-44

 

ISSN:0094-243X

 

年代: 1904

 

DOI:10.1063/1.1796579

 

出版商: AIP

 

数据来源: AIP

 

摘要:

The hard X‐ray microprobe provides an effective methodology for the non‐destructive analysis of inhomogeneous materials. Application of X‐ray absorption/fluroescence spectroscopy techniques (XANES and EXAFS) permits the speciation of the elements and yields information about the local structural environment. Microfocussed, monochromatic, tunable X‐rays allows examination of small areas of micrometer dimensions with spectroscopic procedures. Typically the materials which are presented are thick and cannot be altered for the experiment. This condition introduces difficulties which may compromise the results. Herein we discuss those difficulties and show that the system can yield reliable results in spite of the compromises. Some results are presented on the two iron meteorites we have examined. These specimens are representative of highly inhomogeneous materials and illustrate the difficulties encountered with compositional variations which may occur at sub‐millimeter dimensions and also illustrate the difficulties presented by the need to analyze components present at ppm concentration levels in a concentrated matrix. In these particular samples the major constituent is Fe which ranges from 90&percent; to 70&percent;, balanced by Ni which ranges from 10&percent; to 30&percent;. The critical diagnostic trace elements Ga and Ge which must also be analyzed are present at the 80 and 340 ppm level respectively. These diagnostic elements have been shown by EXAFS to be substitutionally placed in the matrix of the major element species in these meteorite samples. © 2004 American Institute of Physics

 

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