Ion trap

In an ion trap, ions, ie electrically charged atoms or molecules held by electrical and magnetic fields. Depending on the type and strength of the applied fields can be selectively hold ions of a particular mass "caught". Alternatively, you can keep all the ions in the trap stock and ions of a particular mass found by changing the fields and then scan the ion reservoir targeted mass separated.

Development

1953 developed the physicist Wolfgang Paul to save the theory, ions in an electric oscillating quadrupole field. The concept of the Paul trap was for analysts only of secondary interest, since only ions of a particular m / z ratio were stored.

1983, the method by George Stafford (1983 ) was expanded, which led to a breakthrough of this technology in analytical chemistry because now storing all masses and a selective removal were possible.

Methodology

The storage of the ions takes place in a vacuum and without contact with a surface. There are different versions of the ion trap, the most commonly used are the Paul trap and the Penning trap.

In the Paul trap a time-varying electromagnetic field is used to capture ions. In the form of a quadrupole field by this, the case is also referred to as a quadrupole trap. The Paul trap is closely related to the quadrupole mass spectrometer.

A different shape of the ion trap is the Penning trap. In this, a combination of time- constant electric field and also temporally constant magnetic field to a storage of ions.

Several other types exist. In an Electron Beam Ion Trap a highly focused electron beam is used in combination with static electric fields, for example. The Electrostatic Ion Beam Trap uses only electrostatic fields by a beam of ions to save at relatively high kinetic energy.

Ion traps have applications in mass spectrometry, optical spectroscopy and precision in the construction of quantum computers.

Example of the application of a Paul trap in analytics

Of end caps and the ring electrode is connected to an alternating voltage in the radio frequency range. With proper tension, the trajectories of the masses become unstable, and only the ions with exactly matching m / z ratio to remain in the trap, this one uses for ion selection.

Benefits

With ion trap mass spectrometers multiple shock experiments can be carried out in succession. Fragments obtained can be selected and further fragmented targeted. The signal -to-noise ratio is better, according to the sensitive devices.

More word meanings

• The ion trap also means the early television technology is called.
• In biology, the ion trap refers to the taking of biomembrangängigen neutral fabrics such as are ionized in the vacuole of plant cells there in the slightly acidic environment (pH about 5.8 ) by addition of protons and so the biomembrane the vacuole ( tonoplast ) no longer permeate and can not leave the vacuole. For example, as the vacuole of onion skin cells are stained with neutral without the cells die, which is detectable by plasmolysis.

• Spectroscopy
• Atomic physics