High speed polarity switch time-of-flight spectrometer

Patent metadata

Field	Value
Publication number	US-9870910-B2
Application number	US-201415105099-A
Country	US
Kind code	B2
Filing date	Nov 28, 2014
Priority date	Dec 24, 2013
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A mass spectrometer and method is provided for a time-of-flight analyzer (TOF) having an accelerator stage with a plurality of electrodes to receive and accelerate a plurality of ions, and a drift chamber downstream of the accelerator stage for receiving at least a portion of the accelerated ions. The TOF analyzer also has a pulser coupled to the accelerator stage for applying one or more voltages to the plurality of electrodes and a controller coupled to the pulser to adjust one or more voltages applied to the electrodes to configure the accelerator stage to receive and accelerate positive and negative ions during different cycles of an ion detection period.

First claim

What is claimed is:

1. A mass spectrometer, comprising
a time-of-flight (TOF) analyzer, comprising
an accelerator stage comprising a plurality of electrodes and adapted to receive and accelerate a plurality of ions,
a drift chamber disposed downstream of said accelerator stage for receiving at least a portion of the accelerated ions,
a pulser coupled to the accelerator for applying one or more voltages to said plurality of electrodes,
a controller coupled to the pulser and adapted to cause the pulser to adjust one or more voltages applied to said electrodes so as to configure the accelerator stage to receive and accelerate positive and negative ions during different cycles of an ion detection period, and
an ion deflector disposed downstream of said accelerator stage so as to deflect accelerated positive and negative ions along different trajectories for passage through at least a portion of said drift chamber.

2. The TOF analyzer of claim 1 , further comprising one of a positive ion mirror disposed downstream of said deflector and configured to receive the positive ions from said deflector and to reflect the received positive ions toward said ion detector and a negative ion mirror disposed downstream of said deflector and configured to receive the negative ions from said deflector and to reflect said received negative ions toward said ion detector.

3. A method of performing mass spectroscopy using a time-of-flight (TOF) analyzer, comprising:
providing an accelerator stage comprising a first electrode, a second electrode disposed downstream of the first electrode, and a third electrode downstream of the second electrode,
configuring the accelerator stage of said TOF analyzer to receive and accelerate positive and negative ions during different,cycles for detecting positive and negative ions,
passing the accelerated positive and negative ions during each of said cycles through a drift chamber,
detecting at least a portion of the ions after their passage through the drift chamber in each of said cycles,
maintaining said first and second electrodes at a ground electric potential during a first phase of a cycle for detecting positive ions so as to allow accumulation of a plurality of positive ions in a space between said first and second electrodes,
applying equal positive voltages to said first and second electrodes during a second phase of said cycle so as to inhibit entrance of additional positive ions into the space between said first and the second electrodes and to create an electric field between the second and said third electrode,
applying a voltage differential between said first and second electrodes during a third phase of said cycle so as to accelerate the ions accumulated in the space between the first and second electrodes toward said drift chamber, and
maintaining said first and second electrodes at the end electric potential during a fourth phase of said cycle in which the accelerated ions pass through the drift chamber.

4. The method of claim 3 , wherein at least one cycle for detecting ions of the first polarity has a partial temporal overlap with at least one cycle for detecting ions of the opposite polarity to the ions of the first polarity.

5. The method of claim 3 , wherein said step of configuring said accelerator stage comprising switching polarity of one of more voltages applied to one or more electrodes of said accelerator.

6. The method of claim 3 , further comprising providing at least one positive voltage source and at least one negative voltage source and a plurality of switches for selectively coupling said voltage sources to said plurality of electrodes.

7. The method of claim 6 , wherein one or more said switches are selectively activated and deactivated to change polarity of one or more voltages applied to said one or more electrodes so as to configure said accelerator stage from a positive ion mode to a negative ion mode.

8. The method of claim 6 , wherein said ion source supplies positive ions to said accelerator stage when the accelerator stage is in a positive ion mode and supplies negative ions to the accelerator stage when the accelerator stage is in a negative ion mode.

9. The method of claim 8 , wherein said third electrode is disposed in proximity of an entrance of said drift chamber and wherein said third electrode is maintained at the electric ground potential.

10. The method of claim 3 , wherein said fourth phase of said cycle has a temporal overlap with a first phase of a subsequent cycle for detecting ions.

11. The TOF analyzer of claim 3 , wherein said first and second electrodes are maintained at the ground electric potential during a first phase of a cycle for detecting negative ions so as to allow accumulation of a plurality of negative ions in a space between said first and second electrodes.

12. The TOF analyzer of claim 11 , wherein said controller causes the puiser to apply the same negative voltages to said first and second electrodes during a second phase of said cycle so as to inhibit entrance of additional negative ions into the space between the first and the second electrodes and to create an electric field between the second and third electrodes.

13. The TOF analyzer of claim 12 , wherein said controller causes the voltage source to apply a voltage differential between said first and second electrodes during a third phase of said cycle so as to accelerate the negative ions accumulated in the space between the first and second electrodes toward said drift chamber.

14. The TOF analyzer of claim 13 , wherein said controller causes the puller to maintain said first and second electrodes at the ground electric potential during a fourth phase of said cycle in which the accelerated negative ions pass through the drift chamber.

15. The method of claim 14 , wherein said fourth phase of said cycle has a temporal overlap with a first phase of a subsequent cycle for detecting ions.

Assignees

• Dh Technologies Dev Pte Ltd
• Dh Technologies Dev Pte Ltd

Inventors

• Haufler Robert
• Dima Martian

Classifications

• H01J49/40 Primary

  Time-of-flight spectrometers (H01J49/36 takes precedence) · CPC title

• H01J49/0095

  Particular arrangements for generating, introducing or analyzing both positive and negative analyte ions (ion/ion reactions H01J49/0072) · CPC title