Go Big! The Potsdam SIMS User Facility
In this contribution to the “Go Big! Large-Scale Facilities” series, the Potsdam SIMS User Facility tells us about the variety of applications of Secondary Ion Mass Spectrometry (SIMS) in geosciences and how researchers from around the world can access the CAMECA 1280-HR instrument in Germany.
Are you working to reconstruct past climates or track paleoenvironmental changes in fossils? Or perhaps you are interested in determining the origin of mineralizing fluids that form economically viable ore deposits – and whether bacteria played a role? Maybe you want to uncover when a mountain range formed and the sequence of geological events that shaped it. Or are you studying the rate at which elements diffuse in minerals? If your samples are small, precious, or highly heterogeneous, and all you need to answer these questions is an isotope ratio from a domain as tiny as one-tenth the thickness of a human hair, then the GFZ Helmholtz Centre for Geosciences might have just what you need: a SIMS instrument!
About the Potsdam SIMS User Facility
The Potsdam SIMS User Facility, affiliated with Section 3.1 of the GFZ Helmholtz Centre for Geosciences, operates a fully equipped, large-geometry Secondary Ion Mass Spectrometry (SIMS) CAMECA 1280-HR instrument, supported by a comprehensive range of peripheral instrumentation. The SIMS laboratory is an open user facility designed to support the needs of the global geochemical community. Scientists from Europe, southern Africa, and beyond are invited to contact us to discuss collaboration opportunities. The lab team includes not only GFZ staff but also PhD students and postdoctoral researchers on extended visits. The team also includes the virtual SIMS facility at the University of the Witwatersrand in South Africa, which was established to benefit the southern African scientific community by providing approved users with Internet-based remote access to the Potsdam 1280-HR.
What is Secondary Ion Mass Spectrometry, and how can it be applied in geosciences?
SIMS instruments use a finely focused ion beam to analyze a microvolume of a solid sample. A small fraction of the material sputtered from the sample’s polished surface is ionized during this process, and these secondary ions are then accelerated into a mass spectrometer, where they are separated based on their mass-to-charge ratio. The key advantages of SIMS are its high sensitivity and low detection limits (in the ng/g range for many elements) compared to other microbeam techniques. Operating under ultra-high vacuum conditions, SIMS can detect nearly all elements in the periodic table, including atmospheric species. Additionally, the high spatial resolution, with typical spot sizes of 10-15 µm in diameter and less than 2 µm in depth, makes it particularly useful for in situ studies of small, rare, or highly heterogeneous samples.
The range of applications for the SIMS method in geosciences is largely limited by the availability of well-characterized, homogeneous, and matrix-matched reference materials of known isotopic and elemental compositions, which are essential to quantify instrumental factors biasing SIMS ratios from “true” values. This means that if, for example, you wish to analyze boron isotope ratios in tourmaline, you need one or more tourmaline reference materials that have been previously characterized for their boron isotope ratios using bulk methods.
The Potsdam SIMS lab is continuously developing new methods and reference materials. Some of the routine isotope ratio applications that operate in an automated ‘point-and-analyze’ mode include:
- Boron (B) isotopes in tourmaline and glass;
- Carbon (C) isotopes in diamond and calcite;
- Chlorine (Cl) isotopes in apatite;
- Nitrogen (N) isotopes in diamond;
- Lithium (Li) isotopes in tourmaline;
- Oxygen (O) isotopes in zircon, quartz, calcite, barite, anhydrite, gypsum, apatite and serpentine;
- Sulfur (S) isotopes in pyrite, barite, anhydrite and gypsum;
- Uranium-Lead (U-Pb) geochronology of zircon, titanite, and apatite.
Although isotope ratio analyses are the primary focus of most projects at our facility, the Potsdam 1280-HR instrument is also used to measure mass fraction of light trace elements (e.g., H2O and CO2 in basaltic glasses) and has the ability to provide elemental distribution maps. Another operational mode includes depth profiling, which involves analyzing isotopic or elemental variations as a function of depth, typically allowing the quantification of diffusion profiles with a depth resolution of approximately 20 nm.
If you are wondering what the applications of such results are, they have a broad range of uses: from studying magmatic and metasomatic processes in minerals at the microscale to reconstructing tectonic plate movement, exploring paleoclimates, or searching for critical raw materials, and even conducting cosmochemistry research.
How are samples prepared?
Samples intended for analysis using SIMS can include grain mounts, thin sections, or even polished rock disks or slices, but they must be flat and polished to within micrometer tolerances. The most common sample geometry is a round 1-inch mount, though the lab’s website provides further information on other possible geometries. If you are not sure which embedding materials (e.g. epoxy) is best suited for your samples, check out a detailed study by the Edinburgh SIMS facility that also provides further guidelines related to the sample preparation for SIMS.
The care that you take in preparing your sample mount is the most critical factor influencing the quality of the data that are ultimately obtained. For those projects that are approved for accessing the Potsdam SIMS facility, we recommend contacting the lab team before beginning any sample preparation to ensure the highest data quality from the CAMECA 1280-HR.
How long does it take to perform SIMS analyses?
In general, the time required for data acquisition using a SIMS instrument depends on the abundance of the isotopes targeted for measurement. Single-spot analyses of isotope ratios for major elements, such as δ¹³C in calcite, take only 3–4 minutes. However, measurements for trace elements, such as U-Pb geochronology of zircon and fluorapatite, require longer counting times on the order of 15-20 minutes per spot. Routine analyses with large-geometry SIMS instruments can be automated. However, this marks only the beginning of the SIMS data acquisition process. Further data reduction and inspection of all analysis pits for potential cracks and inclusions, using optical and scanning electron microscopy, add several more days of work.
I’m hooked…where can I learn more about SIMS?
The team at the Potsdam SIMS facility actively participates in the training of early career scientists in SIMS technology either with extended student visits or with the organization of yearly short courses. If you are interested in learning more about SIMS, or visiting the Potsdam SIMS facility, sign up for the short course “Introduction to Secondary Ion Mass Spectrometry in the Earth Sciences” that takes place annually. The next one is scheduled for 1st to 5th September 2025 at the GFZ Helmholtz Centre for Geosciences, Germany.
The course’s participants will be exposed to all basic aspects of SIMS: fundamentals of vacuum technology, theory of secondary ion generation and matrix effects, data assessment and realistic assessment of this technique’s strengths and limitations. Read a EAG blog contribution from a participant from the 2023 course to find out more on what you can expect!
There will be no charges for course participation, however participants will be responsible for covering their own travel and accommodation costs while in Potsdam. If you wish to register for the SIMS short course, please visit https://sims.gfz-potsdam.de/short-course/ and complete the registration form.
Who uses the large geometry SIMS instrument in the Potsdam SIMS lab? Can I apply for access?
Nearly all work conducted in the Potsdam SIMS lab falls into one of two categories: (1) approved collaborative projects that will lead to publications in the international scientific literature, and (2) internal projects focused on enhancing the facility’s capabilities, particularly through the development of new reference materials that are subsequently made available to interested laboratories through the IAGeo Limited. All scientists wishing to use the facility as well as the virtual SIMS facility must submit a research proposal, which will be evaluated for both scientific merit and the level of technical effort required to achieve the project’s stated objectives.
Graduate students who secure funding for an extended stay (minimum of 3 months) at the Potsdam SIMS facility may apply for the opportunity to use the 1280-HR instrument free of charge for an agreed number of days. The goal of this program is to provide young scientists with advanced training in SIMS technology.
More about the Potsdam SIMS User Facility
The Potsdam SIMS lab is based at the GFZ Helmholtz Centre for Geosciences, Section 3.1 Inorganic and Isotope Geochemistry. Find out more at https://sims.gfz-potsdam.de/
Contribution by Alicja Wudarska (Polish Academy of Sciences & GFZ Helmholtz Centre for Geosciences), Maria Rosa Scicchitano (GFZ Helmholtz Centre for Geosciences), Michael Wiedenbeck (GFZ Helmholtz Centre for Geosciences), and Sarah Glynn (University of the Witwatersrand & GFZ Helmholtz Centre for Geosciences). Edited by the EAG Communications Committee.
Image credits: lab team photo by Vignesh Kumar Balasundar (CAMECA); vSIMS lab photo by Sarah Glynn; SEM-CL microphotograph by Siri Simonsen (University of Oslo); sample and instrumentation photos by Alicja Wudarska; guest scientists’ photo by Maria Rosa Scicchitano; and short course photo by Frédéric Couffignal.