Principle : Mass spectrometry, secondary ionization (sims, an abbreviation of the english ” secondary ion mass spectrometry “) detects very low concentrations of dopants and impurities. it can give depth profiles elementary covering a large range, ranging from a few angstroms (å) to tens of microns (µm). it’s based on an irradiation of the target to be analysed by heavy ions, or by clusters polyatomic loaded (clusters), possibly with neutral particles. the energy of the incident beam (primary beam) is a few hundreds of electronvolts to 50 kev. the interaction of the incident beam with the material is reflected by the spray of the target in the form of particles, charged or not (ions, or secondary particles). it is these ionised particles during the spray process (or sometimes by post-ionization of neutral particles sputtered) that are filtered by mass (perhaps energy) to go to the composition of the sample target.
Technical Documentation
Chemical analysis: Mass spectroscopy of secondary ions
Interest/Objective:
This technique allows you to :
- a very high sensitivity (very low detection limits in the ppb range in favorable cases) to substantially all of the elements of the periodic classification (trace analysis) ;
- access to isotopic analysis elemental (use of tracers isotope measure isotope ratios of the same element) ;
- the determination of concentration profiles from the surface over distances that can be highly variable depending on the application, of a few tens of nm to a few tens of µm (for the analysis of thin layers or release profiles) with an excellent depth resolution ;
- the possibility, in static mode, access to the composition, possibly molecular, the first layers of atomic or molecular ;
- the spatial localization and imaging 2d and 3d with a good resolution, lateral (often better than 0.1 µm), and depth, of the elements, or, in some cases, of the chemical species ;
- the use of chemical effects that are called “matrix” to identify, and possibly quantify, the chemical compounds ;
- – the possibility, under certain conditions, to identify chemical compounds or fractions of molecular of these compounds contained in the material analyzed.
- Chemical analysis: Mass spectroscopy of secondary ions
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