The operation of TOF-SIMS involves several steps. First, a primary ion beam, typically composed of ions such as Bi+ or Ga+, is directed at the sample surface. The energy from this beam ejects secondary ions from the sample. These secondary ions enter a mass spectrometer where they are accelerated towards a detector. Since the ions are accelerated to the same kinetic energy, their time of flight is inversely proportional to the square root of their mass. This allows the instrument to distinguish between different ions and create a mass spectrum.
