Secondary-Ion Mass Spectrometry

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Secondary-ion mass spectrometry (SIMS) is used to analyse the composition of solid surfaces and thin films by sputtering the surface of the specimen with a focused primary ion beam and collecting and analysing ejected secondary ions. The mass/charge ratios of these secondary ions are measured with a mass spectrometer to determine the elemental, isotopic, or molecular composition of the surface to a depth of 1 to 2 nm.

SIMS is generally considered to be a qualitative technique, although quantitation is possible with the use of standards.  SIMS is the most sensitive surface analysis technique, with elemental detection limits ranging from parts per million to parts per billion.

ICAM equipment includes:

  • Physical Electronics (PHI) TRIFT III Time-of-Flight SIMS at the University of Illinois at Urbana-Champaign. The TOF-SIMS uses energetic ions to bombard a sample in vacuum and produce secondary ions. These ions are extracted in an electric field and mass-to-charge separated at the detector due to their difference in velocity.  Both surface scans and depth profiles are possible with this system.
  • FEI FIB200-SIMS, Ion microscope with micro-manipulators at Imperial College London. Used to image surfaces with secondary ions at a nano-scale lateral resolution, sub 100 nm.  Features in-situ micro-manipulators for small sample handling using sharp probes and micro-gripper tools and micro-mechanical measurement system.
  • Cameca NanoSIMS 50L, Magnetic sector SIMS at The University of Manchester. High spatial resolution SIMS instrument with the ability to image at nanoscale resolution (down to 50nm).