Mass spectrometer with beam expander

Patent metadata

Field	Value
Publication number	US-9245728-B2
Application number	US-201514730551-A
Country	US
Kind code	B2
Filing date	Jun 4, 2015
Priority date	Jun 8, 2010
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

A mass spectrometer is disclosed comprising a RF confinement device, a beam expander and a Time of Flight mass analyzer. The beam expander is arranged to expand an ion beam emerging from the RF confinement device so that the ion beam is expanded to a diameter of at least 3 mm in the orthogonal acceleration extraction region of the Time of Flight mass analyzer.

First claim

The invention claimed is:

1. A mass spectrometer comprising:
a Time of Flight mass analyzer comprising an orthogonal acceleration extraction region;
said mass spectrometer further comprising an ion beam expander arranged and adapted to expand an ion beam so that said ion beam has a diameter or a cross-sectional width>6 mm in said orthogonal acceleration extraction region.

2. A mass spectrometer as claimed in claim 1 , wherein said ion beam expander is arranged and adapted to expand said ion beam so that said ion beam has a diameter or a cross-sectional width>7 mm, >8 mm, >9 mm or >10 mm in said orthogonal acceleration extraction region.

3. A mass spectrometer as claimed in claim 1 , wherein said ion beam expander is arranged and adapted to expand said ion beam so that said ion beam has a diameter or a cross-sectional width of x mm in said orthogonal acceleration extraction region, wherein x is selected from the group consisting of: (i) 6-7; (ii) 7-8; (iii) 8-9; (iv) 9-10; (v) 10-11; (vi) 11-12; (vii) 12-13; (viii) 13-14; (ix) 14-15; (x) 15-16; (xi) 16-17; (xii) 17-18; (xiii) 18-19; (xiv) 19-20; (xv) 20-21; (xvi) 21-22; (xvii) 22-23; (xviii) 23-24; (xix) 24-25; (xx) 25-26; (xxi) 26-27; (xxii) 27-28; (xxiii) 28-29; (xxiv) 29-30; (xxv) 30-31; (xxvi) 31-32; (xxvii) 32-33; (xxviii) 33-34; (xxix) 34-35; (xxx) 35-36; (xxxi) 36-37; (xxxii) 37-38; (xxxiii) 38-39; (xxxiv) 39-40; and (xxxv) >40.

4. A mass spectrometer as claimed in claim 1 , wherein said Time of Flight mass analyzer is arranged downstream of an RF ion confinement device, and wherein said ion beam expander is arranged downstream of said RF ion confinement device, said ion beam expander being arranged and adapted to expand the ion beam which emerges, in use, from said RF ion confinement device.

5. A mass spectrometer as claimed in claim 4 , wherein said RF ion confinement device comprises an ion guide or ion trap.

6. A mass spectrometer as claimed in claim 4 , wherein said mass spectrometer further comprises a first vacuum chamber, a second vacuum chamber and a differential pumping aperture arranged between said first vacuum chamber and said second vacuum chamber, wherein said RF ion confinement device is located in said first vacuum chamber and said Time of Flight mass analyzer is arranged in said second vacuum chamber.

7. A mass spectrometer as claimed in claim 6 , wherein said ion beam expander comprises a first Einzel lens arranged in said first vacuum chamber and a second Einzel lens arranged in said second vacuum chamber.

8. A mass spectrometer as claimed in claim 4 , wherein the distance L between an ion exit of said RF confinement device and the longitudinal mid-point of said orthogonal acceleration extraction region is selected from the group consisting of: (i) >100 mm; (ii) 100-120 mm; (iii) 120-140 mm; (iv) 140-160 mm; (v) 160-180 mm; (vi) 180-200 mm; (vii) 200-220 mm; (viii) 220-240 mm; (ix) 240-260 mm; (x) 260-280 mm; (xi) 280-300 mm; (xii) 300-320 mm; (xiii) 320-340 mm; (xiv) 340-360 mm; (xv) 360-380 mm; (xvi) 380-400 mm; and (xvii) >400 mm.

9. A mass spectrometer as claimed in claim 4 , wherein said ion beam which emerges, in use, from said RF ion confinement device has a first cross section, a first positional spread and a first velocity spread and wherein said ion beam in said orthogonal acceleration extraction region has a second cross section, a second positional spread and a second velocity spread, and wherein:
(i) said second positional spread is greater than said first positional spread; or
(ii) said second velocity spread at a particular position is less than said first velocity spread at a particular position; or
(iii) a maximum diameter or maximum cross-sectional width of said first cross section is less than a maximum diameter or maximum cross-sectional width of said second cross section.

10. A mass spectrometer as claimed in claim 1 , wherein said Time of Flight mass analyzer comprises a pusher electrode and a first grid electrode, wherein said orthogonal acceleration extraction region is arranged between said pusher electrode and said first grid electrode, and wherein in use at least some ions located in said orthogonal acceleration extraction region are orthogonally accelerated into a drift region of said Time of Flight mass analyzer.

11. A mass spectrometer as claimed in claim 10 , wherein said Time of Flight mass analyzer further comprises a second grid electrode arranged downstream of said first grid electrode, a field free region arranged downstream of said second grid electrode and upstream of an ion detector.

12. A mass spectrometer as claimed in claim 11 , wherein said Time of Flight mass analyzer is arranged so that ions pass from said first grid electrode to said second grid electrode, through said field free region to said ion detector without being reflected in the opposite direction.

13. A mass spectrometer as claimed in claim 1 , wherein said Time of Flight mass analyzer comprises a reflectron.

14. A mass spectrometer as claimed in claim 1 , wherein said Time of Flight mass analyzer is arranged and adapted to analyze positive ions and said mass spectrometer further comprises a further Time of Flight mass analyzer arranged and adapted to analyze negative ions, wherein said further Time of Flight mass analyzer is arranged adjacent to said Time of Flight mass analyzer.

15. A mass spectrometer as claimed in claim 1 , wherein said ion beam expander comprises one or more Einzel lenses or other ion-optical devices.

16. A method of mass spectrometry comprising:
providing a Time of Flight mass analyzer comprising an orthogonal acceleration extraction region; and
expanding an ion beam using an ion beam expander so that said ion beam has a diameter or a cross-sectional width>6 mm in said orthogonal acceleration extraction region.

17. A method of mass spectrometry as claimed in claim 16 , further comprising providing an RF ion confinement device and arranging said Time of Flight mass analyzer downstream of said RF ion confinement device, so that the ion beam which emerges from said RF ion confinement device is expanded.

Assignees

• Micromass Ltd

Inventors

• Brown Jeffery Mark
• Gilbert Anthony James
• Hoyes John Brian
• Langridge David J
• Wildgoose Jason Lee

Classifications

• H01J49/0031

  Step by step routines describing the use of the apparatus (H01J49/0081 takes precedence) · CPC title

• H01J49/062

  Ion guides (linear ion traps performing mass selection H01J49/4225, mass filters H01J49/421) · CPC title

• H01J49/405

  characterised by the reflectron, e.g. curved field, electrode shapes · CPC title

• H01J49/401 Primary

  characterised by orthogonal acceleration, e.g. focusing or selecting the ions, pusher electrode · CPC title

• H01J49/403

  characterised by the acceleration optics and/or the extraction fields · CPC title