Ion optic components for mass spectrometers

• US 20010035498A1
• Filed: 12/22/2000
• Published: 11/01/2001
• Est. Priority Date: 05/24/2000
• Status: Active Grant

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Li, Gangqiang, Russ, Charles W. IV
• Granted Patent: US 6,593,570 B2
• Time in Patent Office: Days
• US Class Current: 250/398
• 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 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second element and wherein the length of said openings are at least about 20% of the length of said second element, said first element and said second element each being adapted independently to receive a voltage to generate within said second element an oscillating electric potential field having predetermined characteristics.

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 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second 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, said first element and said second element each being adapted independently to receive a voltage to generate within said second element an oscillating electric potential field having predetermined characteristics.

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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second element and wherein the length of each of said openings is at least about 20% of the length of said second element, said first element and said second element each being adapted independently to receive a voltage to 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 manipulating charged particles, said method comprising:

(a) directing charged particles from a source thereof into a zone,

(b) generating a first electrical potential in said zone, and

(c) simultaneously generating a second electrical potential outside said zone, wherein said second electrical potential penetrates into said zone and combines with said first electrical potential to form a resultant oscillating electric potential field having sub-fields of alternating polarity that subjects said charged particles to oscillatory motion.

24. A method according to

claim 23

wherein said charged particles are ions.

25. A method according to

claim 23

wherein said first electrical potential has an oscillating voltage component.

26. A method according to

claim 23

wherein said manipulating is selected from the group consisting of transporting, collisional cooling, collisional induced dissociating and collisional focusing.

27. A method for creating an oscillating electric potential field having sub-fields of alternating polarity, said method comprising:

(a) generating a first electrical potential in a zone, and

(c) simultaneously generating a second electrical potential outside said zone, wherein said second electrical potential penetrates into said zone and combines with said first electrical potential to form said oscillating electric potential field having sub-fields of alternating polarity.

28. A method for creating an oscillating electric potential field having sub-fields of alternating polarity, 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 in a wall thereof wherein said openings are radially disposed with respect to the axis of said second 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, wherein at least one of said voltages has an oscillating voltage component.

29. A method according to

claim 28

wherein said first element and said second element are cylindrical.

30. A method for transporting charged particles, 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second 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 during transport through said second element.

31. A method according to

claim 30

wherein said voltage applied to said first element comprises an oscillating voltage component.

32. A method according to

claim 30

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

33. A method according to

claim 30

wherein the length of each of said openings is at least 50% of the length of said second element.

34. 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second 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.

35. A method according to

claim 34

wherein said voltage applied to said first element comprises an oscillating voltage component.

36. A method according to

claim 34

wherein said charged particles are subjected to harmonic oscillation by an oscillating electric potential field having sub-fields of alternating polarity.

37. 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second 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.

38. A method according to

claim 37

wherein said voltage applied to said first element comprises an oscillating voltage component.

39. A method according to

claim 37

wherein said charged particles are subjected to oscillation by an oscillating electric potential field having sub-fields of alternating polarity.

40. A method according to

claim 37

wherein said second element comprises at least two segments.

41. A method according to

claim 40

wherein different voltages are applied to said segments.

42. An 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second 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, said first element and said second element each being adapted independently to receive a voltage to generate within said second element an oscillating electric potential field having predetermined characteristics.

43. An apparatus according to

claim 42

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.

44. An apparatus according to

claim 42

wherein said first element and said second element are metal cylinders.

45. An 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second element and wherein the length of said openings are at least about 20% of the length of said second element, said first element and said second element each being adapted independently to receive a voltage to generate within said second element an oscillating electric potential field having predetermined characteristics, wherein said apparatus is disposed between at least two vacuum chambers.

46. 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 in a wall thereof wherein said openings are elongated and radially disposed with respect to the axis of said second element and wherein the length of each of said openings is at least about 20% of the length of said second element, said first element and said second element each being adapted independently to receive a voltage to 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.