Ion probes allow three types of analyses:
- Point analysis : a stationary or rastering primary beam is used to know the composition in a point with a spot size between 5-20µm
- Depth profiling: the progressive erosion of the sample surface using a scan of a small surface (raster) allows monitoring of the variations of composition as a function of depth
- Imaging : an image of either elemental or isotopic variations in composition with a spatial resolution of roughly 1µm
As CASA center is equipped with a NanoSIMS instrument with a high spatial resolution, by far higher than the SIMS, we usually do not do imaging.
The measurements accuracy allowed by the IMS 1280 HR can be as low as conventional bulk technique (e.g. 2SD for oxygen isotopes is 0.2-0.3‰).
Accurate isotopic analysis requires matching of the chemical matrix composition (to a few % weight) and the unknown sample, as well as a match of the structure. Chemical variations due to solid solutions, present in many glasses and crystals, requires a series of standards wich cover the range in composition to be analyzed (with respect to major elements).
SwissSIMS analytical portofolio:
| Material | Elements/isotopes routinely analyzed |
| Quartz | d18O, d30Si, traces elements (Li, Al, Ti, Fe) |
| Glass | d18O, d7Li, d11B, d30Si, d37Cl, volatile contents, dD, Mg-Al isotopes |
| Biotite | d18O, volatile contents |
| Sulfure | D34S, d56Fe |
| Micas | d18O, OH |
| Feldspars | d18O |
| Graphite | d13C |
| Organic matter | d13C, D33S |
| Apatite | d18O, d37Cl, d34S |
| Calcite, dolomite | d13C, d18O |
| Olivine | d18O, d56Fe, Mg-Al isotopes |
| Diamonds | d13C |
| Zircon | d18O, U-Pb dating |
| Monazite | d18O, U-Pb dating |
| Tourmaline | d18O, d11B |
| Garnet | d18O, d7Li |
SwissSIMS precisions for regular (~10-15µm) spot size
- δ7Li: ± 1‰ 2SD or better for [Li] > 20 ppm
- δ11B: ± 1‰ 2SD or better for [B] > 20 ppm; ± 0.3‰ 2SD in tourmaline
- δ13C: ~ ± 1‰ 2SD
- δ18O: ± 0.3‰ 2SD
- δ30Si: ± 0.3‰ 2SD
- δ34S: ± 0.3‰ 2SD
- δ37Cl: ± 0.4‰ 2SD for [Cl] > 100 ppm
- δ56Fe: ± 0.3‰ 2SD
- Cl, F, H2O: F-H2O: 0.3 – 0.6% s.e., Cl: 1% s.e. (F-OH-rich minerals)
- Trace elements: ~ ± 10 %