Quasi-planar multi-reflecting time-of-flight mass spectrometer

Patent metadata

Field	Value
Publication number	US-10141175-B2
Application number	US-201615244931-A
Country	US
Kind code	B2
Filing date	Aug 23, 2016
Priority date	Jul 16, 2008
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A multi-reflecting, time-of-flight (MR-TOF) mass spectrometer including two quasi-planar electrostatic ion mirrors extended along drill direction (Z) and formed of parallel electrodes, separated by a field free region. The MR-TOF includes a pulsed ion source to release ion packets at a small angle to X-direction which is orthogonal to the drill direction Z. Ion packets are reflected between ion mirrors and drill along the drift direction. The mirrors are arranged to provide time-of-flight focusing ion packets on the receiver. The MR-TOF mirrors provide spatial focusing M the Y-direction orthogonal to both drift direction Z and on injection direction X. In a preferred embodiment, at least one mirror has a feature providing periodic spatial focusing of ion packets in the drift Z-direction.

First claim

What is claimed is:

1. A multi-reflecting time-of-flight mass spectrometer comprising:
two quasi-planar electrostatic ion mirrors extended along a drift Z-direction and formed of parallel electrodes, wherein said mirrors are separated by a field-free region;
a pulsed ion source to release ion packets at a small angle to an X-direction which is orthogonal to the drift Z-direction, such that the ion packets are reflected between the ion mirrors and drift along the drift Z-direction direction;
a receiver to receive the ion packets;
wherein said mirrors are positioned to provide time-of-flight focusing on said receiver and provide spatial focusing in a Y-direction orthogonal to both the drift Z-direction and the ion injection X-direction;
wherein at least one of said mirrors has a periodic feature providing modulation of electrostatic field along the drift Z-direction for the purpose of periodic spatial focusing of the ion packets in the Z-direction; and
wherein said periodic feature comprises at least one of the following:
at least one mirror electrode having an opening varying in height in the Y-direction;
at least one mirror electrode with varying width along the X-direction; or
a set of periodic lenses incorporated into an internal electrode of at least one of said mirrors.

2. The multi-reflecting time-of-flight mass spectrometer as defined in claim 1 and further including at least one end deflector for reverting ion path in the drift direction.

3. The multi-reflecting time-of-flight mass spectrometer as defined in claim 1 and further including at least one isochronous curved interface between said pulsed ion source and said receiver.

4. The multi-reflecting time-of-flight mass spectrometer as defined in claim 1 and further including at least two lenses in the field-free region.

5. The multi-reflecting time-of-flight mass spectrometer as defined in claim 1 , wherein at least one of said mirrors comprises at least four electrodes with at least one electrode having attracting potential applied thereto to provide said time-of-flight focusing and said spatial focusing in the Y-direction.

6. The multi-reflecting time-of-flight mass spectrometer as defined in claim 1 , wherein said periodic feature comprises a set of auxiliary electrodes incorporated into at least one mirror electrode and wherein a potential of the auxiliary electrodes varies periodically in the Z-direction.

7. The multi-reflecting time-of-flight mass spectrometer as defined in claim 1 , wherein said periodic feature has a period equal N*ΔZ/2, where N is an integer number and ΔZ is an advance in the drift direction of an ion jigsaw trajectory per reflection.

8. The multi-reflecting time-of-flight mass spectrometer as defined in claim 1 , wherein said periodic feature has a period equal to integer number of periods of an jigsaw trajectory.

9. A method of time-of-flight analysis comprising the steps of:
forming packets of analyzed ions;
passing ion packets between two parallel and quasi-planar ion mirrors extended along a drift Z-direction while retaining relatively small velocity component of the ion packets along the Z-direction such that the ion packets move along a jigsaw ion trajectory;
receiving ions at a receiver;
focusing the ion packets in time and spatially focused in direction Y;
spatially and periodically modulating an electrostatic field within at least one mirror in order to provide for spatial focusing of the ion packets along the Z-direction;
applying an end potential to an end of a single mask window electrode disposed between the two ion mirrors; and
applying a main potential to a center of the mask window, wherein the end potential is different than the main potential to produce a deflecting field at the end of the mask window.

10. The method as defined in claim 9 and further comprising a step of reverting the direction of ion drift at the edges of an analyzer.

11. The method as defined in claim 9 and further comprising injection of ion packets via a curved isochronous interface.

12. The method as defined in claim 9 and further comprising spatial focusing of ion packets within a drift space between said mirrors by at least two lenses.

13. The method as defined in claim 9 , wherein said step of periodically modulating electrostatic field within at least one of said mirrors comprises a step of spatial modulation of the shape of at least one mirror electrode.

14. The method as defined in claim 9 , wherein said step of periodically modulating electrostatic field within at least one of said ion mirrors comprises a step of introducing periodic field of auxiliary electrodes.

15. The method as defined in claim 9 , wherein the period of said modulation equals to N*ΔZ/2, where N is an integer number and ΔZ is an advance in the drift direction of said ion jigsaw trajectory per reflection.

16. The method as defined in claim 9 , wherein said step of forming ion packets includes step of ion accumulation of ions coming from a continuous ion source.

17. The method as defined in claim 9 , wherein the strength of periodic focusing in the Z-direction is adjustable.

18. The method as defined in claim 9 , wherein spatial focusing of the ion packets along the Z-direction is done by a periodic feature, the periodic feature comprising at least one of the following:
at least one mirror electrode with an opening varying in height in the Y-direction;
at least one mirror electrode with varying width along an X-direction; or
a set of periodic lenses incorporated into an internal electrode of at least one of said mirrors.

19. A method of time-of-flight analysis comprising the steps of:
forming packets of analyzed ions;
passing ion packets between two parallel and quasi-planar ion mirrors extended along a drift Z-direction while retaining relatively small velocity component of the ion packets along the Z-direction such that the ion packets move along a jigsaw ion trajectory;
receiving ions at a receiver;
focusing the ion packets in time and spatially focused in direction Y;
spatially and periodically modulating an electrostatic field within at least one mirror in order to provide for spatial focusing of the ion packets along the Z-direction by a periodic feature, the periodic feature comprising at least one of the following:
at least one mirror electrode with an opening varying in height in the Y-direction;
at least one mirror electrode with varying width along an X-direction; or
a set of periodic lenses incorporated into an internal electrode of at least one of said mirrors.

Assignees

• Leco Corp

Inventors

• Verentchikov Anatoli N
• Yavor Mikhail I

Classifications

• H01J49/22

  Electrostatic deflection · CPC title

• H01J49/0031

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

• H01J49/406 Primary

  with multiple reflections · CPC title