Quantitative trace element imaging using PIXE and the nuclear microprobe

The X‐ray spectra of pure elements, excited using MeV energy beam of protons from the nuclear microprobe, have known spectra signatures. This makes X‐ray spectra for more complex mixtures amenable to decomposition into contributions from the component elements. By devising this procedure as a matrix operation that transforms directly from spectrum vector to elemental concentration vector, the decomposition can be performed very efficiently enabling the real‐time projection of the component element signals. In the case of a raster‐scanned beam, with data that contain position information for each X‐ray event, this approach enables the real‐time projection of component element spatial distribution images. This paper describes the matrix transform approach called dynamic analysis (DA), which enables on‐line real‐time imaging of major and trace elements using proton‐induced X‐ray emission (PIXE). The method also provides off‐line iterative yield corrections to these images to compensate for changing sample composition across an image area. The resulting images are quantitative in two respects: (1) they resolve the pure element components and strongly reject interferences from other elements and (2) they can be directly interrogated for sample composition at each pixel, over areas, or along lines across the image area, with accuracy comparable to microanalytical point analysis methods. The paper describes the DA method, presents tests, and discusses its application to quantitative major and trace element imaging in geology. © 2001 John Wiley & Sons, Inc. Int J Imaging Syst Technol 11, 219–230, 2000

[1]  William L. Griffin,et al.  Quantitative pixe microanalysis of geological matemal using the CSIRO proton microprobe , 1990 .

[2]  F. Meyer,et al.  True elemental imaging of pyrites from Witwatersrand reefs , 1995 .

[3]  C. Ryan,et al.  PIXE profiling, imaging and analysis using the NAC proton microprobe: Unraveling mantle eclogites , 1995 .

[4]  John L. Campbell,et al.  PIXE: A Novel Technique for Elemental Analysis , 1988 .

[5]  W. Reimold,et al.  PIXE microanalysis of gold-pyrite associations from the Kimberley Reefs, Witwatersrand basin, South Africa , 1999 .

[6]  W. Griffin,et al.  The CSIRO-GEMOC Nuclear Microprobe: a high-performance system based on a new closely integrated design , 1999 .

[7]  C. Koeberl,et al.  Micro-PIXE analysis of varied sulfide populations from the Ventersdorp Contact Reef, Witwatersrand basin, South Africa , 1999 .

[8]  C. A. Pineda,et al.  Elemental mapping using proton-induced x-rays† , 2001 .

[9]  Pjm Peter Brands,et al.  A system for on-line monitoring of light element concentration distributions in thin samples , 1999 .

[10]  C. Ryan The nuclear microprobe as a probe of earth structure and geological processes , 1995 .

[11]  David N. Jamieson,et al.  Materials Analysis Using a Nuclear Microprobe , 1996 .

[12]  Microanalysis of ore-forming fluids using the scanning proton microprobe , 1995 .

[13]  David N. Jamieson,et al.  Dynamic analysis: on-line quantitative PIXE microanalysis and its use in overlap-resolved elemental mapping , 1993 .

[14]  D. R. Cousens,et al.  SNIP, A STATISTICS-SENSITIVE BACKGROUND TREATMENT FOR THE QUANTITATIVE-ANALYSIS OF PIXE SPECTRA IN GEOSCIENCE APPLICATIONS , 1988 .

[15]  C. Ryan Advances in fluid inclusion analysis using the nuclear microprobe , 1999 .

[16]  G. Stevens,et al.  Micro-PIXE elemental imaging of pyrites from the Bulawayan-Bubi Greenstone Belt, Zimbabwe , 1999 .

[17]  T. Awaya A new method for curve fitting to the data with low statistics not using the χ2-method , 1979 .

[18]  David N. Jamieson,et al.  A new method for on-line true-elemental imaging using PIXE and the proton microprobe , 1995 .

[19]  D. R. Cousens,et al.  Quantitative analysis of PIXE spectra in geoscience applications , 1990 .

[20]  B. Kamber,et al.  Single mineral PbPb dating , 1995 .

[21]  P. R. Bevington,et al.  Data Reduction and Error Analysis for the Physical Sciences , 1969 .

[22]  C. Ryan,et al.  Segregation of ore metals between magmatic brine and vapor; a fluid inclusion study using PIXE microanalysis , 1992 .

[23]  C. Ryan,et al.  Weighting measures in fitting PIXE spectra , 1990 .

[24]  C. Churms,et al.  A VAX and PC-based data acquisition system for MCA, scanning and list-mode analysis , 1993 .