2
Principles of Operation
Overview of Ion Optics and Mass Analyzer
8
TSQ Altis, Quantis, and Fortis Hardware Manual
Thermo Scientific
No.
Item
Description
1.
Sweep cone
The ions pass through the sweep cone into the vacuum system
2.
RF lens and exit lens
In the RF lens, which is a series of stainless-steel electrodes, the MS applies
an RF voltage to the electrodes. As the RF amplitude increases, ions of
progressively higher mass-to-charge ratios (
m/z)
pass through to the exit
lens. The exit lens acts as a vacuum baffle before the ion beam enters the
next region of the optics, which is at lower pressure.
3.
MP00 RF lens and lens L0
The MP00 RF lens generates an electric field that guides the ions along
the axis of the lens. At Lens L0, the MS applies a positive electrical
potential for positive ions and a negative one for negative ions to be
detected.
4.
MP0 Ion Optics
The Multipole MP0 generates an electric field that guides the ions along
the axis of the multipole rods (
). Because the rods are curved, the
charged ions follow the curve.
5.
Beam blocker
The neutral species in the ion beam strike the neutral beam blocker and are
removed from the ion beam.
6.
Quadrupole 1
The ions pass to quadrupole 1 (Q1), which can act as a mass filter or as an
ion transmission device.
• Mass filter: RF and DC voltages are applied, and only the selected
mass goes through. The paths of the other ions become unstable and
hit the rods.
• Ion transmission device: RF voltage is applied and all ions go through.
7.
Lenses EL21, EL22, EL23
Lenses EL21, EL22, and EL23 shield Q1 from the RF voltage that is
applied to Q2 and focus the ion beam. These lenses also help to keep the
collision gas out of Q1.
8.
Quadrupole 2
The ion beam enters quadrupole 2, (Q2). Q2 can act as an ion
transmission device or as a collision cell.
• Ion transmission device: RF voltage is applied and all ions go through.
• Collision cell: Adding pressurized argon gas and an offset voltage
fragments the ions.
9.
Lenses EL31, EL32, EL33
The ions go through lenses EL31, EL32, and EL33. These lenses help to
contain the argon gas in Q2 and focus the beam of the fragments.
10.
Quadrupole 3
The fragments enter quadrupole 3, (Q3). Q3 can act as a mass filter or as
an ion transmission device like Q1.
11.
Dual-mode, discrete-dynode
detector
Ions and electrons strike the electron multiplier and release a cascade of
electrons. The detector converts the current of the electrons to a voltage
that the data system records.
