Thermo Scientific TSQ Series Hardware Manual page 48

2
Functional Description
Mass Spectrometer
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 collision-induced dissociation (CID) can take place if the
argon collision gas is present in the cell.
Figure 28. Magnitude of the rf and dc voltages applied to the rods of the Q1 and Q3 mass analyzers
Mass Analysis
The mass analyzers (Q1 and Q3) are square arrays of precision-machined and precision-aligned
hyperbolic or round-profile rods. The rods are charged with a variable ratio of rf voltage and dc
voltage
ions with a specific mass-to-charge ratio and unstable oscillations to all others.
At any given instant, one particular set of rf and dc voltage values is being applied to the mass
analyzer rods. Under these conditions, only ions of one mass-to-charge ratio (for example, m/z
180) are maintained within bounded oscillations as their velocity carries them through the mass
analyzer. At the same time, all other ions undergo unbounded oscillations. These ions strike one of
the rod surfaces, become neutralized, and are pumped away, or they are ejected from the rod
assembly.
30 TSQ Series Hardware Manual
Voltage
(v)
Atomic mass units
(Figure 28). These potentials give rise to an electrostatic field that gives stable oscillations to
(u)
RF voltage
10,000 V P/P
840 V dc voltage
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