SIMS Measurement of Stable Isotopes

This chapter reviews the external reproducibility improvement to a level commensurate with the internal measurement errors of stable isotopes. Secondary ion mass spectrometry (SIMS) is a versatile technique for analyzing solid materials. SIMS uses a primary ion beam to sputter a solid sample and produce secondary ions. It offers an in situ analytical capability with spatial resolution of down to 50 nm for imaging and around 10-30 μm for high precision isotopic analysis. Isotopic compositions can be measured from the secondary ions of a variety of elements including those of the common stable isotopes (H, C, N, O, S) and rock-forming elements (Li, B, Mg, Si). Real advances in SIMS have been in stable isotope research allowing in situ negative ion analysis and these areas are only beginning to be exploited. The general features of stable isotope analysis by SIMS are also covered in this chapter. SIMS is accomplished with ion microprobes or ion microscopes which use focused primary ion beams either in static or scanning mode to analyze samples. SIMS allows real-time assessment of data and responsive control of the analytical program.