Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS)
ION-TOF Model IV Time-of-Flight Secondary Ion Mass Spectrometer
Schematic: Pulsed primary ions, typically liquid metal ions, are used to bombard the sample surface, causing the secondary elemental or cluster ions to emit from the surface.
Instrument Calendar:
ToF-SIMS provides:
- A mass spectrum of the outermost 12Å of a surface
- Identification of structural units present at the surface (e.g. monomeric components and repeat units)
- Fingerprint identification of polymers
- Information on surface degradation and contamination
- Spatial imaging of the surface chemistry
- A full mass spectrum from every pixel of an image
- High mass resolution
- Extremely high analytical sensitivity
- Destructive elemental depth profiles several thousand Å into the sample
Typical Applications:
- Identifying the elemental composition and the chemical status near the surface (around 5 angstrom) with high sensitivity (~1ppm) and high mass resolution (~9000).
- Distinguishing the different isotopes of the same element.
- Imaging the topography of surface using the secondary electrons.
- Mapping chemical species on the submicron scale.
- Ultra-thin depth profiling.
Chemical Map: Map of Si+ distribution on patterned SAM surface; note reverse contrast to second picture
Depth Profile of amorphous Si film formed in modulated gas environment