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Analytical Chemistry

Acceleration Slits

Definition and meaning of Acceleration Slits in chemistry.

Acceleration slits are narrow apertures in a mass spectrometer that shape and confine the ion beam as ions are accelerated by a voltage on their way into the analyzer.

In more detail

Ions formed in the ion source must be accelerated and formed into a narrow, well-defined beam before they can be separated. The acceleration slits do this shaping while the ions pass through the accelerating voltage. Passing through that voltage gives each ion a kinetic energy equal to its charge multiplied by the voltage; because lighter ions then travel faster than heavier ones, the beam can be separated by mass-to-charge ratio.

Key facts

PurposeShape and confine the accelerated ion beam
Typical voltageHundreds to thousands of volts
Used inMass spectrometry
FieldAnalytical Chemistry
Example

In a magnetic-sector mass spectrometer, ions pass through acceleration slits at several kilovolts before entering the magnetic field that separates them by mass.

Frequently asked questions

What do acceleration slits do in a mass spectrometer?

They confine ions into a narrow, well-defined beam as those ions are accelerated by a voltage, so the beam can then be cleanly separated by mass-to-charge ratio.

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