Curved ion guide and related methods

Patent metadata

Field	Value
Publication number	US-9236235-B2
Application number	US-27719808-A
Country	US
Kind code	B2
Filing date	Nov 24, 2008
Priority date	May 30, 2008
Publication date	Jan 12, 2016
Grant date	Jan 12, 2016

Abstract

An ion guide includes a plurality of curved electrodes and an ion deflecting device. The electrodes are arranged in parallel with each other and with a central curved axis, the curved central axis being co-extensive with an arc of a circular section having a radius of curvature, each electrode being radially spaced from the curved central axis, wherein the plurality of electrodes define a curved ion guide region arranged about the curved central axis and between opposing pairs of the electrodes. The ion deflecting device may include a device for applying a DC electric field to two or more of the electrodes in a radial direction. The ion deflecting device may include a pair of curved, parallel ion deflecting electrodes, which are in addition to curved electrodes utilized for applying an RF ion guiding field.

First claim

What is claimed is:

1. An ion guide comprising:
a plurality of curved electrodes arranged in parallel with each other and with a central curved axis, the curved central axis being co-extensive with an arc of a circular section having a radius of curvature, each electrode being radially spaced from the curved central axis, wherein the plurality of electrodes define a curved ion guide region arranged about the curved central axis and between opposing pairs of the electrodes; and
an ion deflecting device configured for applying a radial DC electric field across the ion guide region and along the radius of curvature.

2. The ion guide of claim 1 , wherein the ion deflecting device comprises a DC voltage source communicating with at least one pair of the plurality of electrodes.

3. The ion guide of claim 1 , further comprising an axial DC voltage source configured for applying an axial DC electric field along the curved central axis.

4. The ion guide of claim 1 , further comprising an RF voltage generator communicating with at least one opposing pair of the plurality of electrodes.

5. The ion guide of claim 1 , wherein the plurality of curved electrodes comprises a pair of outer electrodes and a pair of inner electrodes, the outer electrode pair is positioned radially outwardly from the inner electrode pair relative to the radius of curvature, the ion deflecting device comprises a DC voltage source communicating with each electrode of the outer pair and the inner pair, and the DC voltage source is configured for applying a DC voltage of a first magnitude to the outer electrode pair and a DC voltage of a second magnitude to the inner electrode pair.

6. The ion guide of claim 5 , wherein the DC voltage source is configured for applying the DC voltage to the outer electrode pair with a given polarity and the DC voltage to the inner electrode pair with the opposite polarity relative to a voltage at the curved central axis.

7. The ion guide of claim 1 , wherein the plurality of curved electrodes comprises a first pair of opposing ion guiding electrodes and a second pair of opposing ion guiding electrodes, and the ion deflecting device comprises a pair of opposing, curved ion deflecting electrodes, the ion deflecting electrodes being arranged in parallel with each other and with the curved central axis and positioned along the direction of the radius of curvature.

8. The ion guide of claim 7 , wherein the ion deflecting device further comprises a DC voltage source configured for applying a DC voltage of a first magnitude to one of the ion deflecting electrodes and a DC voltage of a second magnitude to the other ion deflecting electrode.

9. The ion guide of claim 8 , wherein the DC voltage source is configured for applying the DC voltage to the one ion deflecting electrode with a given polarity and the DC voltage to the other ion deflecting electrode with the opposite polarity relative to a voltage at the curved central axis.

10. The ion guide of claim 7 , further comprising an RF voltage generator communicating with at least one of the pairs of ion guiding electrodes.

11. The ion guide of claim 7 , wherein the ion deflecting electrodes are positioned outside the ion guide region.

12. The ion guide of claim 1 , wherein the ion deflecting device is configured for applying a the DC voltage having a magnitude of absolute value (V deflect ) proportional to the kinetic energy (KE) of the ion, the inscribed radius (r 0 ) of the plurality of electrodes about the central axis, and the radius of curvature (R), according to the relation V deflect =k×KE×(r 0 /R), and wherein k is a constant of proportionality dependent on the cross-section and dimensions of the plurality of electrodes.

13. A collision cell comprising the ion guide of claim 1 .

14. A method for guiding an ion through an ion guide, the method comprising:
transmitting the ion into a curved ion guide region of the ion guide, the ion guide region being defined by a plurality of curved electrodes arranged in parallel with each other and with a central curved axis, the curved central axis running through the ion guide region co-extensively with an arc of a circular section having a radius of curvature, each electrode being radially spaced from the curved central axis, wherein the curved ion guide region is arranged about the curved central axis and between opposing pairs of the electrodes;
generating a radio-frequency electric field across the ion guide region to focus the ion to motions generally along the curved central axis; and
generating a radial DC electric field across the ion guide region and along the radius of curvature to provide an ion deflecting force directed along the radius of curvature.

15. The method of claim 14 , wherein generating the DC electric field comprising applying a DC voltage potential to at least one pair of the plurality of electrodes.

16. The method of claim 14 , further comprising generating an axial DC electric field along the curved central axis for controlling axial ion velocity.

17. The method of claim 14 , wherein the plurality of curved electrodes comprises a pair of outer electrodes and a pair of inner electrodes, the outer electrode pair is positioned radially outwardly from the inner electrode pair relative to the radius of curvature, and generating the DC electric field comprises applying a DC voltage of a first magnitude to the outer electrode pair and a DC voltage of a second magnitude to the inner electrode pair to create a DC potential difference between the outer electrode pair and the inner electrode pair.

18. The method of claim 17 , wherein generating the DC electric field comprises applying the DC voltage to the outer electrode pair with a given polarity and the DC voltage to the inner electrode pair with the opposite polarity relative to a voltage at the curved central axis.

19. The method of claim 14 , wherein the plurality of curved electrodes comprises a first pair of opposing ion guiding electrodes and a second pair of opposing ion guiding electrodes, generating the radio-frequency electric field comprises applying a radio-frequency voltage potential to two or more of the ion guiding electrodes, and generating the DC electric field comprises applying a DC voltage potential between a pair of opposing, curved ion deflecting electrodes, the ion deflecting electrodes being arranged in parallel with each other and with the curved central axis and positioned along the direction of the radius of curvature.

20. The method of claim 14 , wherein generating the DC electric field comprises applying a DC voltage having a magnitude of absolute value (V deflect ) proportional to the kinetic energy (KE) of the ion, the inscribed radius (r 0 ) of the plurality of electrodes about the central axis, and the radius of curvature (R), according to the relation V deflect =k×KE×(r 0 /R), and wherein k is a constant of proportionality dependent on the cross-section and dimensions of the plurality of electrodes.

21. The method of claim 14 , further comprising evacuating the ion guide and mass-analyzing the ion in relation to one or more ions of different masses transmitted into the ion guide region, or introducing gas molecules into the ion guide and colliding the ion with one or more of the gas molecules.

Assignees

• Muntean Felician
• Steiner Urs
• Agilent Technologies Inc

Inventors

• Muntean Felician
• Steiner Urs

Classifications

• H01J49/063 Primary

  Multipole ion guides, e.g. quadrupoles, hexapoles · CPC title