Quadrupole trap ion isolation method
AssigneeVarian Associates, Inc.
InventorGregory J. Wells
Life of this patent
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Abstract
A method for efficiently filling a QIT which isolates an ion range by employing a sequential part of supplemental broadband waveforms where the first such supplemental broadband waveform is applied during the period that the e-beam ionization bombardment takes place and the second such broadband waveform is applied after the e-beam bombardment ends.
Claims14
In a method for isolating a selected ion having a mass m(p) in a quadrupole ion trap (QIT) system, and said QIT system having a ring electrode, a pair of end caps, and RF trapping voltage applied to said ring electrode, a supplementary voltage generator connected to said end-caps, said method for isolating a selected ion having a mass re(p) including,
- (a) establishing said RF trapping voltage at low value;
- (b) ionizing by electron bombardment the gas inside said QIT for a first period of time;
- (c) during said first period of time applying a first broadband spectrum RF waveform with said supplemental RF generator to said end caps;
- (d) determining the mass spectrum of ions in said QIT;
- (e) substantially immediately after said first period of time, applying a second broadband spectrum RF waveform with said supplemental RF generator to said end caps.
The method of 5 wherein said step (e) broadband waveform comprises at least a higher frequency range and a lower frequency range separated by a frequency notch, said notch including the secular frequency corresponding to said mass m.sub.p.
Dependencies are inferred from the claim text.