Time of Flight Secondary Ions Mass Spectroscopy (TOFSIMS) is a surface sensitive characterisation technique providing “clean” molecular information of a solid sample with high mass resolution, high lateral (< 200 nm) and in-depth (1-5 nm) resolution with high sensitivity in the ppm range.
Thanks to the Hercules Foundation, OCAS has direct access to a state-of-the-art TOFSIMS facility. The set-up consists of a TOFSIMS (IONTOF TOF.SIMS 5) with the latest generation of ion sources for depth profiling and analytical time of flight mass spectrometry with high spatial resolution (BiMn-source) for imaging. It has two ion columns for depth profiling and analysis: The first column allows low energy sputtering (down to 250 eV) using noble gasses such as Ar, Xe, O2 or Cs, which is tuned towards inorganic and organic depth profiling. The second column is devoted to a gas cluster Ar- source (GCIB=gas cluster ion beam) providing ions composed of large Ar+n-clusters (n=1000-5000 Ar atoms in one cluster).
This Ar-cluster beam is unique and can be considered as the most important breakthrough with respect to depth profiling of polymeric structures. The extremely low energy/atom (~1-3 eV) of the Ar-cluster beam eliminates severe mass spectra degradation, resulting in clean molecular information of solid samples. This improves the attainable depth resolution. Moreover, the equipment is enhanced by an “in-situ” Atomic Force Microscope (AFM) module, allowing 3D TOFSIMS analysis.
Advantages of a state-of-the-art TOFSIMS with AFM
- Parallel detection of all ions, organic and inorganic
- Unlimited mass range
- High mass resolution at full transmission
- High lateral (< 200 nm) and in-depth (few nm) resolution
- High sensitivity in the ppm/ppb range
- Surface topography and “real” sputtering rates
The figure below shows the depth profile at silane coating / steel interface using Ar-clusters (a), (b) Optical image of the crater after sputtering and (c) AFM surface profile across the sputter crater (red) and before sputtering (blue).
- Interfacial bonding between organic/metal and polymer/polymer systems
- Study of corrosion protection mechanism
- Adhesion properties
- Inter-diffusion layers
- Coating coverage
- Oil and emulsion residues on metal substrates and their impact on conversion layer formation
- “Defectology” requiring analysis methods combining high sensitivity (with detection limits down to ppm level) and sub-micron lateral resolution
TOFSIMS analysis complements to other available surface sensitive characterisation techniques (but either missing sensitivity, or lateral resolution), such as
“Having access to this state-of-the-art TOFSIMS equipment, perfectly complements OCAS’s in-house surface sensitive characterisation techniques, by adding superior sensitivity, or enhanced lateral resolution.”