structural:scholar_edition
Time-of-flight

The time-of-flight (TOF) analyzer uses an electric field to accelerate the ions through the same potential, and then measures the time they take to reach the detector. If the particles all have the same charge, their kinetic energies will be identical, and their velocities will depend only on their masses. For example, ions with a lower mass will travel faster, reaching the detector first. Ions usually are moving prior to being accelerated by the electric field, this causes particles with the same m/z to arrive at different times at the detector. This difference in initial velocities is often not dependent on the mass of the ion, and will turn into a difference in the final velocity. This distribution in velocities broadens the peaks shown on the count vs m/z plot, but will generally not change the central location of the peaks, since the starting velocity of ions is generally centered at zero. To fix this problem, time-lag focusing/ delayed extraction has been coupled with TOF-MS.