The analysis of nothing and nearly nothing – concepts for reference materials for the Super-SIMS


The analysis of nothing and nearly nothing – concepts for reference materials for the Super-SIMS

Renno, A. D.

The Super-SIMS idea goes back to the year 1979 [1]. Since then several attempts have been made to install such instruments [2-5], although with varied success.
Most of the published data were either analysis of semiconductor materials or isotope ratios of natural materials. Having a strong focus on natural, metal, and mineral resources the Helmholtz Institute Freiberg for Resource Technology installed such a system at the Ion Beam Centre at HZDR. This new Super-SIMS will be embedded into a system of consecutive micro-analytical methods devoted to the characterization of minerals and ores. Therefore, our focus will lie on the analysis of ultra-trace elements in these natural matrices.
Despite the high precision, the accuracy of SIMS analysis can be problematic. The sensitivity factor as well as the instrumental mass fractionation vary with the chemical composition. This so-called matrix effect demands that the sample and the reference material (RM) should have exactly the same chemical composition and structure, this is difficult to achieve. Even trace elements and in the case of the Super-SIMS ultra-trace elements may affect the sensitivity factor. The compromise is the usage of matrix matched RMs.
The combination of good lateral and depth resolution of the SIMS instrument with the resulting small sample volumes / masses (sub ng-range) and the aspired detection limits in the pg/g range yield to the fact that the probability to meet one atom of the analyte in the sample volume will be < 1.
This contribution will stimulate the discussion about the concepts of detection limit, homogeneity and heterogeneity in RMs and present considerations about the design of future RMs for ultra-trace element analysis with the Super-SIMS.

[1] Purser et al. Surface and Interface Analysis 1(1), 1979, 12.; [2] S. Matteson, Mass Spectrom. Rev., 27 (2008) 470.; [3] Ender et al. NIMB 123 (1997) 575.; [4] Maden, PhD thesis, ETH Zurich 2003.; [5] Fahey et al. Analytical Chemistry 88(14), 2016, 7145

Keywords: Reference Materials; SIMS; Super-SIMS

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Publ.-Id: 27247