Page 64 - Inorganic Mass Spectrometry - Fundamentals and Applications

54 Barshick

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Schematic diagram of (a) an electrostatic energy analyzer and (b) a Bessel box
energy analyzer. (From Ref. 19.)

el box is often positioned in front of the quadrupol
window of ions that may enter. An ion entering th
take one of several trajectories (see Fig. 2.1 1). If the ion does not possess a
it
~nimum energy, as determined by the potentials on the Bessel box lenses, is re-
(el). If the energy of the ion is too great,
pelled back toward the entrance aperture
the field does not deflect the ion sufficiently move it around the center stop and it
to
collides with the exit plate (e3). If the ion has the right energy, it is deflected around
the center stop and out the other side (e2).