ToF-SIMS 

Time-of-Flight secondary ion mass spectrometry (ToF-SIMS) enables us to determine the atomic and molecular composition of the outermost 1-3 monolayers of a solid (Static SIMS). The surface under investigation is bombarded by charged particles (ions) with energies up to 30 keV. Resulting secondary ions originating at the surface are analysed with respect to their mass. Elements and molecules can be determined simultaneously. The use of Time-of-Flight mass analysers allows very low detection limits (ppb, fmole). Quantification of the data is possible by use of reference samples. Semiquantitative data can be obtained when the samples to be compared have similar chemistries.

The method yields images with lateral resolutions down to 300 nm, routinely.  By maintaining the ion bombardment, the sample can be "peeled" layer by layer (depth profiling, sputtering, dynamic SIMS). In this way, information about elements is registered as a function of depth. Although in general the intensive ion bombardment will damage organic bonds, it is possible, under certain circumstances, to obtain molecular information (organic depth profiling). When imaging and depth profiling are combined the 3-dimensional build-up of a sample can be made visible (3D-micro area analysis).

The restrictions to samples are relatively minor. Usually, samples can be analysed "as is". The material needs to be stable enough in a vacuum environment. Besides solids, also powders and liquids can be analysed. Further details are available as pdf-file:

Synonyms / Related Techniques

  • Time-of-Flight Secondary Ion Mass Spectrometry
  • Secondary Ion Mass Spectrometry (SIMS)

Case Studies