Thermo Scientific TSQ Quantum XLS, Руководство пользователя

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Functional Description
Mass Spectrometer
Thermo Scientific TSQ Quantum XLS Series User Guide 33
Figure 23. Polarity of the rf and dc voltages applied to the rods of the Q1 and Q3 mass analyzers
The ac voltage applied to the quadrupole rods is of constant frequency (1.123 MHz). The
ac voltage applied to the rods varies from 0 to 10 000 V peak-to-peak, and the dc voltage
varies from 0 to ±840 V. Voltages of the same amplitude and sign are applied to each rod pair.
However, the voltages applied to the other rod pair are equal in amplitude but opposite in
sign.
Because the frequency of this ac voltage is in the radio frequency range, you refer to it as
rf voltage. In
Figure 24 , the solid line represents the combined rf and dc voltage applied to
one rod pair, and the dashed line represents the combined rf and dc voltage applied to the
other rod pair. The ratio of rf voltage to dc voltage determines the ability of the mass
spectrometer to separate ions of different mass-to-charge ratios.
The first and third quadrupole rod assemblies (Q1 and Q3 quadrupoles) can act as mass
analyzers or as ion transmission devices. When both rf and dc voltages are applied, Q1 and
Q3 function as mass analyzers. When only rf voltage is applied, they act as ion transmission
devices. In the ion transmission mode, the quadrupole rod assemblies allow ions in a wide
window of mass-to-charge ratios to pass.
The square quadrupole rod assembly (Q2) operates in the ion transmission mode only.
Surrounding Q2 is a collision cell where CID can take place if the argon collision gas is
present in the cell.
rf voltage
+ dc voltage
rf voltage 180° out of phase
–dc voltage