6
Prefilter and Quadrupole
Thermo Scientific
DSQ II Hardware Manual
185
Second, helium atoms (not ions) coming from the ion source cause noise if they reach the exit
lens or ion detector. This is known as neutral noise. Helium atoms cannot negotiate the bend
in the prefilter. Therefore, the noise is virtually eliminated. This leads to better signal-to-noise
ratio and lower limits of detection. In addition, higher GC helium flows can be used without
causing excessive amounts of noise that would blind an instrument without a curved prefilter
to low-level signals.
Figure 100.
Prefilter
Figure 101.
Quadrupole Mass Filter
Summary of Contents for DSQ II
Page 1: ...DSQ II Hardware Manual 120299 0002 Revision C December 1 2009 ...
Page 4: ......
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Page 36: ...1 Basic Operations Shutting Down the GC MS System 20 DSQ II Hardware Manual Thermo Scientific ...
Page 198: ...5 Ion Source and Inlet Valve Inlet Valve Upgrade 182 DSQ II Hardware Manual Thermo Scientific ...
Page 202: ...6 Prefilter and Quadrupole 186 DSQ II Hardware Manual Thermo Scientific ...
Page 206: ...7 Ion Detector Electron Multiplier 190 DSQ II Hardware Manual Thermo Scientific ...
Page 242: ...226 DSQ II Hardware Manual Thermo Scientific Index ...