Time-of-Flight Secondary Ion Mass Spectrometer (ToF-SIMS)

ToF-SIMS rasters a pulsed ion beam across an area to produce atomic, molecular, and fragment ions characteristic of the surface and near-surface region. This technique has low detection limits (low parts per million to high parts per billion for atomic species; as low as a femtomole for molecular species), excellent surface sensitivity (information depth is about 2 nanometers), and an extremely high mass resolution. While results are typically semi-quantitative, it can provide valuable insight into subtle chemical variations between similar samples. 

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 (submicron scale lateral resolution possible in imaging mode)
  • Ultra-thin depth profiling 
  • Identification of trace-level contaminants 

Instruments

A person leans over a large spherical machine with many cables and components sticking out of it.
IONTOF Model IV ToF-SIMS 
  • 25 keV Bi cluster ion source 
  • Yields a mass spectrum of the outermost 2 nm of a surface 
  • Identifies structural units present at the surface (e.g., monomeric components and repeat units) 
  • Provides fingerprint identification of polymers 
  • Information on surface degradation and contamination 
  • Spatial imaging of surface chemistry with a full mass spectrum from every pixel of an image  
  • High mass resolution (m/Δm > 5000) and analytical sensitivity (down to high ppb) 
  • Several thousand angstrom destructive elemental depth profiles possible with oxygen or cesium ion sputtering 

 

 

Instrument Contact: Stephen Golledge, PhD