Ion ejection from a quadrupole ion trap
AssigneeThermo Fisher Scientific (Bremen) GmbH
InventorsChristian Albrecht Hock, Dmitry Grinfeld, Richard Heming
Life of this patent
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Abstract
A method of ejecting ions to be analyzed from a quadrupole ion trap in which a trapping field is created by one or more RF voltages applied to one or more electrodes of the trap, the method comprising the steps of cooling the ions to be analyzed within the quadrupole ion trap until the ions are thermalized, reducing the amplitude of one or more RF voltages applied to the quadrupole ion trap and applying the reduced amplitude RF voltages for one half cycle after the one or more RF voltages have reached a zero crossing point, turning off the RF voltages applied to the quadrupole ion trap, and ejecting the ions to be analyzed from the quadrupole ion trap.
Claims30
A method of ejecting ions to be analysed from a quadrupole ion trap in which a trapping field is created by one or more RF voltages applied to one or more electrodes of the trap, the method comprising the following steps:
- (a) cooling the ions to be analysed within the quadrupole ion trap until the ions are thermalized;
- (b) reducing the amplitude of one or more RF voltages applied to the quadrupole ion trap and applying the one or more reduced amplitude RF voltages for substantially one half cycle from where the one or more RF voltages have reached a zero crossing point;
- (c) turning off the one or more RF voltages applied to the quadrupole ion trap after the one half cycle;
- steps (a) to (c) being performed in that order;
- and
- (d) ejecting the ions to be analysed from the quadrupole ion trap concurrently with or after step (c).
An ion ejector system for a mass analyser comprising a quadrupole ion trap for containing a buffer gas;
- a RF power supply with one or more outputs electrically connected to one or more electrodes of the quadrupole ion trap;
- an ejection power supply with one or more outputs electrically connected to one or more electrodes of the quadrupole ion trap;
- and a controller electrically connected to the RF power supply and the ejection power supply, the controller arranged to:
- (a) control the RF power supply to supply one or more RF voltages at a first amplitude to one or more electrodes of the ion trap for a first period of time, wherein the first period of time is sufficient for ions within the quadrupole ion trap to become thermalized due to collisions with the buffer gas;
- (b) control the RF power supply after the first period of time to supply one or more RF voltages of a second amplitude to one or more electrodes of the quadrupole ion trap for substantially one half cycle from where the one or more RF voltages have reached a zero crossing point, the second amplitude being smaller than the first amplitude;
- (c) control the RF power supply to turn off the RF voltages applied to the quadrupole ion trap after the one half cycle;
- the controller being arranged to perform (a) to (c) in that order;
- and
- (d) control the ejection power supply to supply one or more ejection voltages to the quadrupole ion trap concurrently with or after (c).
Dependencies are inferred from the claim text.