page_title: Time-of-flight mass spectrometry
section_title: Reflectron TOF
hierarchical_section_title: Time-of-flight mass spectrometry / Reflectron TOF
caption_attribution_description: A dual stage reflectron from an IT-TOF mass spectrometer from Shimadzu. This model is composed of a series of 46 metal disks, each of which receives a greater voltage than the previous disk, which creates a potential gradient. On the left, the reflectron is mounted to the flight tube, which is in turn mounted inside a cylindrical vacuum manifold.
context_page_description: Time-of-flight mass spectrometry is a method of mass spectrometry in which an ion's mass-to-charge ratio is determined via a time of flight measurement. Ions are accelerated by an electric field of known strength. This acceleration results in an ion having the same kinetic energy as any other ion that has the same charge. The velocity of the ion depends on the mass-to-charge ratio. The time that it subsequently takes for the ion to reach a detector at a known distance is measured. This time will depend on the velocity of the ion, and therefore is a measure of its mass-to-charge ratio. From this ratio and known experimental parameters, one can identify the ion.
context_section_description: The kinetic energy distribution in the direction of ion flight can be corrected by using a reflectron. The reflectron uses a constant electrostatic field to reflect the ion beam toward the detector. The more energetic ions penetrate deeper into the reflectron, and take a slightly longer path to the detector. Less energetic ions of the same mass-to-charge ratio penetrate a shorter distance into the reflectron and, correspondingly, take a shorter path to the detector. The flat surface of the ion detector (typically a microchannel plate, MCP) is placed at the plane where ions of same m/z but with different energies arrive at the same time counted with respect to the onset of the extraction pulse in the ion source. A point of simultaneous arrival of ions of the same mass-to-charge ratio but with different energies is often referred as time-of-flight focus.
  An additional advantage to the re-TOF arrangement is that twice the flight path is achieved in a given length of the TOF instrument.
caption: A dual stage reflectron from a Shimadzu IT-TOF instrument. The 46 metal plates carry the voltages which set up the potential gradient.
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