Ion optic components for mass spectrometers

• US 6,593,570 B2
• Filed: 12/22/2000
• Issued: 07/15/2003
• Est. Priority Date: 05/24/2000
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Li, Gangqiang, Russ, Charles W. IV
• Primary Examiner(s): Lee, John R.
• Assistant Examiner(s): Souw, Bernard E.
• Application Number:
  US09/747,242
• Publication Number:
  US 20010035498A1
• Time in Patent Office: 935 Days
• Field of Search: 205/742, 922/23, 310/11, 250/394, 250/281-290, 250/293-297, 250/396.R, 250/397, 250/400, 330/4.7, 376/137, 315/3, 315/5.19, 315/39, 343/791, 342/368, 333/239
• US Class Current: 250/290
• CPC Class Codes: H01J 49/062 Ion guides linear ion traps performing mass selection H01J49/4225, mass filters H01J49/421

Abstract

Apparatus and methods are disclosed for manipulating charged particles. The charged particles are directed from a source thereof into a zone. A first electrical potential is generated in the zone. Simultaneously, a second electrical potential is generated outside the zone. The second electrical potential penetrates into the zone and combines with the first electrical potential to form an oscillating electric potential field having predetermined characteristics sufficient to manipulate the charged particles. The manipulating of the charged particles includes, e.g., transporting, collisional cooling, collisional induced dissociating and collisional focusing. In one embodiment an apparatus comprises a hollow first element and a hollow second element. The second element is disposed within the first element. The second element has at least two openings in a wall thereof. The openings are elongated and radially disposed with respect to the axis of the second element. The length of the openings is at least about 20% of the length of the second element The first element and the second element each are adapted independently to receive a voltage to generate within the second element an electric potential having predetermined characteristics. The apparatus and methods of the invention have particular application to the field of mass spectrometry.

Claims

1. An apparatus for manipulating charged particles, when present, comprising:

(a) a hollow first element, and

(b) a hollow second element, said second element being disposed within said first element, said second element having at least two openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element, wherein the length of said openings are at least about 20% of the length of said second element, and wherein said openings of said second element allow an electric field resulting from the application of electrical voltages to said first element and said second element to enter an area within said second element and generate within said second element an oscillating electric potential field having predetermined characteristics that manipulates charged particles, when present.

2. An apparatus according to claim 1 wherein said second element has from three to eight openings in said wall thereof.

3. An apparatus according to claim 1 wherein said openings have dimensions that are approximately equal.

4. An apparatus according to claim 1 wherein said second element comprises at least two individual segments and each of said segments has at least two openings in said wall thereof wherein the length of said openings is at least about 20% of the length of said segments.

5. An apparatus according to claim 4 wherein each of said segments are independently adapted to receive a voltage.

6. An apparatus according to claim 1 wherein the length of said openings is at least about 50% of the length of said second element.

7. An apparatus according to claim 1 wherein said openings are evenly distributed in said wall of said second element.

8. An apparatus according to claim 1 wherein said first element and said second element are tapered with respect to their axes.

9. An apparatus according to claim 1 wherein said first element and said second elements are straight with respect to their axes.

10. An apparatus according to claim 1 wherein said first element and said second elements are curved with respect to their axes.

11. An apparatus according to claim 1 wherein said openings are tapered with respect to their longest dimension.

12. An apparatus according to claim 1 wherein said first element has at least two segments.

13. An apparatus according to claim 1 wherein said first element and said second element are metal cylinders.

14. A mass spectroscopy apparatus comprising an apparatus according to claim 1.

15. An apparatus for manipulating charged particles, when present, comprising:

(a) a tubular first element, and

(b) a tubular second element, said second element being coaxially disposed within said first element, said second element having from two to eight openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element, wherein the length of each of said openings is at least about 20% of the length of said second element and wherein said openings of said second element allow an electric field resulting from the application of electrical voltages to said first element and said second element to enter an area within said second element and generate within said second element an oscillating electric potential field having predetermined characteristics that manipulates charged particles, when present.

16. An apparatus according to claim 15 wherein said second element comprises at least two individual segments and each of said segments has from two to eight openings in said wall thereof wherein the length of said openings is at least about 20% of the length of said segments.

17. An apparatus according to claim 16 wherein said first element and said second element are metal cylinders and wherein the ends of said first element and said second element are not coplanar.

18. A mass spectroscopy apparatus comprising:

(a) an ion source,

(b) an apparatus adjacent said ion source, said apparatus comprising (i) a tubular first element and (ii) a tubular second element, said second element being coaxially disposed within said first element, said second element having two to eight openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element, wherein the length of each of said openings is at least about 20% of the length of said second element, and wherein said openings of said second element allow an electric field resulting from the application of electrical voltages to said first element and said second element to enter an area within said second element and generate within said second element an oscillating electric potential field having predetermined characteristics,

(c) an electrical source for independently applying voltages to said first element and said second element, and

(d) a mass analyzer adjacent said apparatus of (b).

19. An apparatus according to claim 18 wherein said openings have dimensions that are approximately equal.

20. An apparatus according to claim 18 wherein said second element has at least two segments and each of said segments has from two to eight openings in said wall of thereof.

21. An apparatus according to claim 20 wherein said first element and said second elements are straight.

22. An apparatus according to claim 20 wherein said first element and said second element are metal cylinders.

23. A method for creating an oscillating electric potential field having sub-fields of alternating polarity for manipulating charged particles, when present, said method comprising:

(a) applying a first voltage to a second element of an apparatus comprising (i) a first element and (ii) said second element, said second element being coaxially disposed within said first element, said second element having at least two openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element and wherein the length of each of said openings is at least about 20% of the length of said second element and wherein the dimensions of said openings are approximately equal, and

(b) applying a second voltage to said first element to generate within said second element an oscillating electric potential field having sub-fields of alternating polarity that manipulates charged particles, when present, wherein at least one of said voltages has an oscillating voltage component.

24. A method according to claim 23 wherein said first element and said second element are cylindrical.

25. A method for transporting charged particles, when present, said method comprising:

(a) directing charged particles from a source thereof into a tubular second element of an apparatus comprising (i) a tubular first element and (ii) said tubular second element, said second element being coaxially disposed within said first element, said second element having at least two openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element and wherein the length of each of said openings is at least about 20% of the length of said second element and wherein the dimensions of said openings are approximately equal, and

(b) applying voltages independently to said first element and said second element to generate an oscillating electric potential field having predetermined characteristics sufficient to confine said charged particles, when present, during transport through said second element.

26. A method according to claim 25 wherein said voltage applied to said first element comprises an oscillating voltage component.

27. A method according to claim 25 wherein said charged particles are confined by an oscillating electric potential field having an oscillating force in a direction transverse to the direction of travel of said charged particles.

28. A method according to claim 25 wherein the length of each of said openings is at least 50% of the length of said second element.

29. A method for cooling charged particles, said method comprising:

(a) directing charged particles from a source thereof into a tubular second element of an apparatus in the presence of a neutral gas, said apparatus comprising (i) a tubular first element and (ii) said tubular second element, said second element being coaxially disposed within said first element, said second element having at least two openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element and wherein the length of each of said openings is at least about 20% of the length of said second element, the pressure of said neutral gas being sufficient such that the mean free path of the ion is smaller than the length of said second element, and

(b) applying voltages independently to said first element and said second element to generate an oscillating electric potential field having predetermined characteristics sufficient to bring into harmonic motion said charged particles passing through said second element.

30. A method according to claim 29 wherein said voltage applied to said first element comprises an oscillating voltage component.

31. A method according to claim 29 wherein said charged particles are subjected to harmonic oscillation by an oscillating electric potential field having sub-fields of alternating polarity.

32. A method for subjecting charged particles to collision induced dissociation, said method comprising:

(a) directing charged particles from a source thereof into a tubular second element of an apparatus in the presence of a neutral gas, said apparatus comprising (i) a tubular first element and (ii) said tubular second element, said second element being coaxially disposed within said first element, said second element having at least two openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element and wherein the length of each of said openings is at least about 20% of the length of said second element, the pressure of said neutral gas being sufficient such that the mean free path of the ion is smaller than the length of said second element, and

(b) applying voltages independently to said first element and said second element to generate an oscillating electric potential field having predetermined characteristics sufficient to confine said charged particles passing through said second element during collision induced dissociation.

33. A method according to claim 32 wherein said voltage applied to said first element comprises an oscillating voltage component.

34. A method according to claim 32 wherein said charged particles are subjected to oscillation by an oscillating electric potential field having sub-fields of alternating polarity.

35. A method according to claim 32 wherein said second element comprises at least two segments.

36. A method according to claim 35 wherein different voltages are applied to said segments.

37. An apparatus for manipulating charged particles, when present, said apparatus comprising:

(a) a tubular first element, and

(b) a tubular second element, said second element being coaxially disposed within said first element, said second element having from two to eight openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element and wherein the length of each of said openings is at least about 20% of the length of said second element and wherein the dimensions of said openings are approximately equal and wherein the ends of said first element and said second element are not coplanar, and wherein said openings of said second element allow an electric field resulting from the application of electrical voltages to said first element and said second element to enter an area within said second element and generate within said second element an oscillating electric potential field having predetermined characteristics that manipulates charged particles, when present.

38. An apparatus according to claim 37 wherein said second element comprises at least two individual segments and each of said segments has from two to eight openings in said wall thereof wherein the length of said openings is at least about 20% of the length of said segments.

39. An apparatus according to claim 37 wherein said first element and said second element are metal cylinders.

40. An apparatus for manipulating charged particles, when present, said apparatus comprising:

(a) a hollow first element, and

(b) a hollow second element, said second element being disposed within said first element, said second element having at least two openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element, wherein the length of said openings are at least about 20% of the length of said second element, and wherein said openings of said second element allow an electric field resulting from the application of electrical voltages to said first element and said second element to enter an area within said second element and generate within said second element an oscillating electric potential field having predetermined characteristics that manipulates charged particles, when present, wherein said apparatus is disposed between at least two vacuum chambers.

41. A mass spectroscopy apparatus comprising:

(a) an ion source,

(b) an apparatus adjacent said ion source, said apparatus comprising (i) a tubular first element and (ii) a tubular second element, said second element being coaxially disposed within said first element, said second element having two to eight openings through a wall thereof wherein said openings are elongated in a direction that is substantially parallel to the longitudinal axis of said second element, wherein said openings are distributed around a circumference of said element and wherein the length of each of said openings is at least about 20% of the length of said second element, and wherein said openings of said second element allow an electric field resulting from the application of an electrical voltage applied to said first element to enter an area within said second element and generate within said second element an oscillating electric potential field having predetermined characteristics,

(c) an electrical source for independently applying voltages to said first element and said second element,

(d) a mass analyzer adjacent said apparatus of (b), and

(e) at least two vacuum chambers wherein said apparatus of (b) is disposed therebetween.