MODEL RELEASED. Mass spectrometry. Technician using a time of flight secondary ion mass spectrometer (TOF SIMS) during chemical research. The TOF SIMS is used to analyse the surface of a sample. A pulsed ion beam is used to remove molecules from the subject's surface. The molecules are ionised and accelerated towards a detector. The time it takes them to reach the detector depends on their mass. The advantage of this system is that macromolecules (such as polymers or proteins) are not disintegrated by the beam. TOF SIMS is used in coatings research, microelectronics and surface contamination studies.