Silicates SIMS analysis

Hauri E. (2002) SIMS analysis of volatiles in silicate glasses 2. Isotopes and abundances in Hawaiian melt inclusions. Chem. Geol 183, 115-141. 

SIMS techniques have occupied somewhat of a narrower niche in uranium-series analysis, but have significantly improved Th isotope analysis relative to TIMS for chemically separated samples. The major improvement relative to TIMS is an improvement by about an order of magnitude in efficiency or sample size requirements for silicates. For uranium and/or thorium rich minerals such as carbonates and zircons, both SIMS and laser-ablation MC-ICPMS have been used for the direct in situ analysis of U and Th isotopes (Reid et al. 1997 Stirling et al. 2000) on very small (pg to ng levels of total U and Th) samples, at 10-100 pm scale resolution. 

Mass spectrometric techniques for analysis of Th- U disequilibria were first developed to date corals for paleoclimate research (Edwards et al. 1987). Soon thereafter, workers at Los Alamos National Laboratory (LANE) developed methods for silicate analysis by TIMS (Goldstein et al. 1989). Typical TIMS analysis of MORE requires 0.5 to 1 gram of material in order have an analyzable load of 100 ng of Th. TIMS analyses of U and Th last 2-3 hrs and produce a precision of 0.5-2% (2a). SIMS techniques for measuring Th isotopes have also been developed (England et al. 1992 Layne and Sims 2000). Analysis of Ra and Pa isotopes by TIMS was developed in the early 1990 s significantly increasing the sensitivity over decay counting analysis (Volpe et al. 1993 Cohen and Onions 1993 Pickett et al. 1994 Chabaux et al. 1994). 

SIMS nl Yes Yes Yes Silicate glass <1 pg perg In routine analysis (h)... 

Ottolini, L., Cdmara, E, Hawthorne, FC., Stirling, J. (2002) SIMS matrix effects in the analysis of light elements in silicate minerals comparison with SREF and EMPA data. Am. Mineral, 87,1477-1485. 

It is often the case that complementary surface analysis techniques such as SIMS and XPS can be used together in order to successfully solve a failure or characterisation problem. In such cases, XPS would be used to generate quantitative information, whilst SIMS would provide qualitative clues with respect to the chemistry. An example of this is where XPS has successfully detected and quantified silicon on a surface which is not responding well to bonding with an adhesive, but the chemical form that the silicon is in is not readily apparent, i.e., it could be silica, silicate or silicone. Analysis of the same surface by static SIMS enables the mass spectmm of the sputtered top layer fragments to be determined and ihe presence of m/e ions at 43,73 and 147 confirm that a polydimethyl siloxane is present. 

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