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Parallel-Plate Energy Analyzer: Determines
ion energy distribution and examines ion energy properties
A parallel-plate type electrostatic energy
analyzer consists of two parallel plates separated by a distance d.
One of the plates is electrically grounded while the other is biased to a
positive potential, Vr. Ions
enter through a sampling orifice and transit through a drift tube before
entering the section composed of the two charged plates.
The electrostatic field between these plates causes the ion trajectories
to curve in a parabola. At the
output of the analyzer is a slit that leads to a detector.
Due to the geometry of the system, only ions with a specific
energy-to-charge ratio will reach the detector.
By varying the field between the charged plates, the entire spectrum of
ion energies can be measured. However,
while a doubly charged ion will be accelerated to
twice the kinetic energy of a singly charged ion, they will have the same energy-to-charge ratio.
In order to examine the difference between these states, it is necessary
to use a second instrument, a Time of Flight Mass
Spectrometer (TOF).
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