Secondary Ion Mass Spectrometer (SIMS)
Jeff Vervoort, Washington State University
What is Secondary Ion Mass Spectrometer (SIMS)
Fundamental Principles of Secondary Ion Mass Spectrometer (SIMS)
The interaction of the primary ion beam with the sample (under vacuum) provides sufficient energy to ionize many elements. If the primary beam is composed of positively charged ions, the resultant ionization favors production of negative ions; primary beams of negative ions favor generation of positive ions. Although most atoms and molecules removed from the sample by the interaction of the primary beam and the sample surface (referred to as sputtering) are neutral, a percentage of these are ionized. These ions are then accelerated, focused, and analyzed by a mass spectrometer.
In "dynamic SIMS" mode the primary ion beam exceeds the "static limit" (~1E12 ions/cm2) producing a high yield of secondary ions. This technique is used for "bulk" analysis of elements and isotopes, and is particularly well-suited for analysis of isotopes and trace elements in minerals (e.g. REE in garnet). Alternatively, "static SIMS" uses a much lower energy primary ion beam (usually Ga or Cs). This technique is typically used for analysis of atomic monolayers on material surfaces to obtain information about molecular species on material surfaces (e.g. organic compounds; see module on Time-of-Flight SIMS.
Secondary Ion Mass Spectrometer (SIMS) Instrumentation - How Does It Work?
- Large radius forward and reverse geometry instruments have been developed that can measure trace elemental and isotopic compositions in individual minerals with a spatial resolution down to roughly 10 microns. These applications include U-Th-Pb geochronology of zircon and other accessory minerals (e.g., SHRIMP).
- Large radius, double focusing instruments are also capable of measuring the isotopic composition of low atomic number elements such as O with similar spatial resolution (e.g., Cameca 1280) or even less for major constituents (e.g., 50 nanometers; NanoSIMS by Cameca Instruments)
- Smaller radius, double focusing instruments offer very high sensitivity (detection limits) for trace element analyses, roughly 10x the sensitivity of microprobes that utilize beams of electrons (e.g., Cameca IM 7f). These instruments can also used to "map" the distribution of individual elements in a sample.
- Some SIMS utilize other types of mass spectrometers (e.g., time-of-flight, quadrupole) and are used primarily for surface characterization, molecular analysis, and depth profiling.
Strengths and Limitations of Secondary Ion Mass Spectrometer (SIMS)?
- The analysis consumes very little sample (essentially non-destructive); for example, a typical U-Th-Pb analysis only consumes a few cubic micrometers of sample.
- High sensitivity also means that samples with low concentration levels (down to ppb levels) can be analyzed with SIMS. As a result, the SIMS is used to determine trace element abundances in meteorites, interplanetary dust, and other samples of limited size and are widely in the semiconductor industry to identify trace constituents in non-conducting substrates.
- High sensitivity also allows for depth profiling of elemental and molecular abundances as well as isotopic ratios.
- In situ analysis eliminates the need for complex sample preparation in most cases, i.e., minerals may be analyzed directly either as grain mounts or in thin sections.
User's Guide - Sample Collection and Preparation
Data Collection, Results and Presentation
The following literature can be used to further explore Secondary Ion Mass Spectrometer (SIMS)
- Fitzsimons I.C.W., Harte B. and Clark R.M. (2000) SIMS stable isotope measurement: counting statistics and analytical precision. Mineral. Mag. 64 59-83
- Hervig, R. L., Mazdab, F. K., Williams, P., Guan, Y., Huss, G. R., Leshin, L. A. (2006) Useful ion yields for Cameca IMS 3f and 6f SIMS: Limits on quantitative analysis. Chemical Geology, 227, 83-99.
- Hinton R.W. (1990) Ion microprobe trace element analysis of silicates: Measurement of multi-element glasses. Chem. Geol. 83 11-25
- Hinton, R. W. (1995) Ion Microprobe Analysis in Geology. IN: P.J. Potts, J.F.W. Bowles, S.J.B. Reed, and M.R. Cave (eds), Microprobe Techniques in the Earth Sciences. Chapman and Hall, pp 235-290.
- Slodzian G. (1980) Microanalyzers Using Secondary Ion Emission. Advances in Electronics and Electronic Physics. Supplement 13B
- De Laeter, John R.(2001) Mass spectrometry (including SIMS, ICP-MS, Accelerator MS, TIMS) Applications of inorganic mass spectrometry, John Wiley & Sons, New York, 474pp.
- Swart P.K. (1990) Calibration of the Ion Microprobe for the Quantitive Determination of Strontium, Iron, Manganese and Magnesium in Carbonate Minerals.
- Secondary Ion Mass Spectrometry: Basic Concepts, Instrumental Aspects, Applications, and Trends, by A. Benninghoven, F. G. Rudenauer, and H. W. Werner, Wiley, New York, 1987 (1227 pages).
- Page FZ, Ushikubo T, Kita NT, Riciputi LR, Valley JW (2007) High precision oxygen isotope analysis of picogram samples reveals μm gradients and slow diffusion in zircon. Am. Mineral. 92:1772-1775.
- Kelly JL, Fu B, Kita NT, Valley JW (2007) Optically Continuous Silcrete Cements Of The St. Peter Sandstone: Oxygen Isotope Analysis By Ion Microprobe And Laser Fluorination. Geochem. Cosmochim. Acta. 71:3812-3832.
- Cavosie AJ, Valley JW, Wilde SA, EIMF (2006) Correlated microanalysis of zircon: Trace element, δ18O, and U-Th-Pb isotopic constraints on the igneous origin of complex >3900 Ma detrital grains. Geochim Cosmochim Acta 70: 5601-5616.
- Valley JW (2001) Stable Isotope Thermometry at High Temperatures: In: Valley JW and Cole DR (eds). Stable Isotope Geochemistry, Reviews In Mineralogy and Geochemistry, vol. 43, p. 365-414.
- Valley, J. W., Graham, C. M., Harte, B., Kinny, P., and Eiler, J. M. (1998) Ion microprobe analysis of oxygen, carbon, and hydrogen isotope ratios. In: McKibben, M.A., et al. (eds), Soc. Econ. Geol. Rev. in Econ. Geol. 7, 73-98.
- Eiler, J. M., Graham, C., and Valley, J. W. (1997) SIMS analysis of oxygen isotopes: matrix effects in complex minerals and glasses. Chemical Geol. 138, 221-244.
- Valley, J. W. and Graham, C. M. (1991) Ion microprobe analysis of oxygen isotope ratios in metamorphic magnetite-diffusion reequilibration and implications for thermal history. Contr. Mineral. Petrol. 109, 38-52.
For more information about Secondary Ion Mass Spectrometer (SIMS) follow the links below.
- SIMS Theory Tutorial from Evans Analytical Group Laboratories
- SIMS Facility – Sandia National Laboratory and University of New Mexico; Basics explained and Trace Element Analysis.
- The Wisconsin Secondary Ion Mass Spectrometry Lab–includes Powerpoint and PDF files on instrumentation and applications
- UCLA SIMS Facility – including information about sample preparation, U-Pb tutorial.
- USGS- Stanfard SHRIMP-RG Facility – sample preparation, applications, research results.
- Australian National University SHRIMP page
- Geological Survey of Canada SHRIMP II Facility
Teaching Activities and Resources
Teaching activities, labs, and resources pertaining to Secondary Ion Mass Spectrometer (SIMS).