Ei/Ci Ion Source - Thermo Scientific TSQ Quantum XLS User Manual

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Functional Description
Mass Spectrometer

EI/CI Ion Source

26 TSQ Quantum XLS Series User Guide
The EI/CI ion source forms gas phase sample ions from sample molecules that elute from the
GC or are introduced by the direct sample probe. See
source in either the electron ionization (EI) or chemical ionization (CI) mode. See
Modes" on page 3.
Figure 15. Ion source of the TSQ Quantum XLS Series mass spectrometer
EI/CI source
PCB
Ion source
block
The ion volume, located in the center of the ion source, is the site where electrons interact
with sample or reagent gas molecules to form ions. Three exchangeable ion volumes and
ion volume holders are available for use in the ion source. See
volume depends on the ionization mode. The open EI ion volume is open on the analyzer
end, with a relatively large electron entrance hole. The closed EI ion volume has a smaller ion
exit hole than the EI ion volume. This results in a higher pressure of analyte and greater
sensitivity, but less dynamic range. The CI ion volume is closed on the analyzer end, except
for a small ion exit hole and a relatively small electron entrance hole. In the CI mode, you
must maintain a relatively high reagent gas pressure.
Figure 15. You can operate the ion
Magnets and
magnet yoke
Heater ring
L1, L2, L3, lens
assembly
"Ionization
Filament
Heated Q0 quadrupole
assembly
Figure 16. The choice of ion
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