Time-of-Flight - Basic Principles

MALDI generated a great demand for mass analyzers which are suitable to be used in conjunction with a naturally pulsed ion source and capable of transmitting ions of extremely high mass up to several 10 u [25]. Since then, the performance of TOF instmments has tremendously increased [26,27]. TOF analyzers have been adapted for use with other ionization methods and - together with orbitraps and FT-ICR instmments - have superseded the established magnetic sector instmments in most applications [26,28], 

The main advantages of TOF instruments are i) that in principle, the m/z range is unlimited [29,30] ii) from each ionizing event, i.e., a single laser shot in MALDI, a complete mass spectrum is obtained within several tens of microseconds Hi) improved transmission of TOF analyzers, with high sensitivity iv) TOF instrument design and construction is comparatively simple and inexpensive and v) recent instruments allow for accurate mass measurements and tandem MS experiments [31]. 

Oscilloscope output of the electron ionization TOF spectrum of xenon on a Bendix TOF-MS. The dark lines are a grid on the oscilloscopic screen. (For the isotopic pattern of Xe cf. Fig. 3.1.) Adapted from Ref. [21] with permission. Pergamon Press, 1959. 

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