Secondary ion mass spectrometry

In Secondary Ion Mass Spectrometry (SIMS) a focused beam of energetic ions (so-called primary ions) is targeted onto the surface of a solid sample. Primary ions dissipate their energy, leading to the sputtering and ionisation of the outmost atoms of the sample surface. The resulting secondary ions are accelerated and transferred to a magnetic analyser. SIMS is applicable to the determination of the isotopic and trace, minor (and to some limited extent, major) element composition across the entire periodic table for any solid material compatible with high-vacuum conditions. Elemental and isotopic analysis can be performed locally down to the nm scale or along depth profiles resulting in 2D surface (ion imaging) or 3D volume (ion tomography) images with a resolution range between 50 nm and 5 μm. A concise overview of the technical background of secondary ionisation as well as the numerous applications of this technique in geochemistry and cosmochemistry, material science, Nuclear Safeguards and life sciences is given.