Time-of-Flight Analysis of a Continuous Beam of Ions by a Detector Array

Patent metadata

Field	Value
Publication number	US-2016336161-A1
Application number	US-201415105089-A
Country	US
Kind code	A1
Filing date	Dec 6, 2014
Priority date	Dec 31, 2013
Publication date	Nov 17, 2016
Grant date	—

Abstract

Systems and methods are provided for time-of-flight analysis of a continuous beam of ions by a detector array. A sample is ionized using an ion source to produce a continuous beam of ions. An electric field is applied to the continuous beam of ions using an accelerator to produce an accelerated beam of ions. A rotating magnetic and/or electric field is applied to the accelerated beam to separate ions with different mass-to-charge ratios over an area of a two-dimensional detector using a deflector located between the accelerator and the two-dimensional detector. An arrival time and a two-dimensional arrival position of each ion of the accelerated beam are recorded using the two-dimensional detector. Alternatively, an electric field that is periodic with time is applied in order to sweep the accelerated beam over a periodically repeating path on the two-dimensional rectangular detector.

First claim

1 . A time-of-flight mass (TOF) spectrometer for analyzing a continuous beam of ions using a rotating magnetic field, comprising:
an ion source that ionizes a sample producing a continuous beam of ions; an accelerator that receives the continuous beam and applies an electric field to the continuous beam of ions producing an accelerated beam of ions; a two-dimensional detector that records an arrival time and a two-dimensional arrival position of each ion of the accelerated beam impacting the two-dimensional detector; and a deflector located between the accelerator and the two-dimensional detector that receives the accelerated beam and applies a rotating magnetic field to the accelerated beam to separate ions with different mass-to-charge ratios in the accelerated beam over an area of the two-dimensional detector.

2 . The TOF mass spectrometer of claim 1 ,
wherein the deflector comprises coils of wire wrapped around a cylindrical core and receives the accelerated beam of ions through the center of the core.

3 . The TOF mass spectrometer of claim 1 ,
wherein the rotating magnetic field separates ions in the accelerated beam by magnetic deflection so that at any given instant the ions of the accelerated beam are arranged in a spiral pattern on the two-dimensional detector, and wherein ions of increasing mass-to-charge ratio are separated monotonically along the spiral pattern inward toward the center of the spiral pattern.

4 . The TOF mass spectrometer of claim 1 ,
wherein the mass range of ions that are recorded by the two-dimensional detector and the mass resolving power of the two-dimensional detector are determined by the following operating parameters: the kinetic energy per charge applied by the accelerator, the period of the rotating magnetic field, the field strength of the rotating magnetic field, the length of the region over which the magnetic field is applied, and the distance between the deflector and the two-dimensional detector.

5 . The TOF mass spectrometer of claim 1 , further comprising
a processor in communication with the accelerator, the deflector, and the two-dimensional detector that
receives an arrival time and a two-dimensional arrival position for each ion impacting the two-dimensional detector and
calculates a time-of-flight for each ion impacting the two-dimensional detector from the arrival time and the two-dimensional arrival position.

6 . The TOF mass spectrometer of claim 5 ,
wherein the processor calculates a time-of-flight for each ion impacting the two-dimensional detector from the arrival time and the two-dimensional arrival position by combining both radial and angular components of the two-dimensional arrival position with respect to the direction of the accelerated beam wherein the radial component provides the integer part of the time-of-flight measured in units of the rotation period of the magnetic field and the angular component provides the fractional part of the time-of-flight.

7 . The TOF mass spectrometer of claim 1 ,
wherein the deflector further applies a rotating electric field to the accelerated beam that increases the deflection of each ion in the accelerated beam by the same radial displacement.

8 . The TOF mass spectrometer of claim 1 ,
wherein the rotating magnetic field is rotated at a constant frequency.

9 . The TOF mass spectrometer of claim 1 ,
wherein the rotating magnetic field is rotated with regular variations in the rotation period.

10 . A method for analyzing the time-of-flight of a continuous beam of ions using a rotating magnetic field, comprising:
ionizing a sample using an ion source to produce a continuous beam of ions; applying an electric field to the continuous beam of ions using an accelerator to produce an accelerated beam of ions; applying a rotating magnetic field to the accelerated beam to separate ions with different mass-to-charge ratios in the accelerated beam over an area of a two-dimensional detector using a deflector located between the accelerator and the two-dimensional detector; and recording an arrival time and a two-dimensional arrival position of each ion of the accelerated beam using the two-dimensional detector.

11 - 15 . (canceled)

16 . A time-of-flight mass (TOF) spectrometer for analyzing a continuous beam of ions using a rotating electric field, comprising:
an ion source that ionizes a sample producing a continuous beam of ions; an accelerator that receives the continuous beam and applies an electric field to the continuous beam of ions producing an accelerated beam of ions; a two-dimensional detector that records an arrival time and a two-dimensional arrival position of each ion of the accelerated beam impacting the two-dimensional detector; and a deflector located between the accelerator and the two-dimensional detector that receives the accelerated beam and applies a rotating electric field to the accelerated beam to separate ions with different mass-to-charge ratios in the accelerated beam over an area of the two-dimensional detector,
wherein the separation includes both a radial component and an angular component and
wherein each component is a function of the mass-to-charge ratio of the ions.

17 . The TOF mass spectrometer of claim 16 ,
wherein the TOF mass spectrometer is operated to send accelerated ions of a target range of mass-to-charge ratios through the deflector with transit times of at least 0.2 rotation periods of the rotating field and up to one period of the rotating field to achieve radial separation of the accelerated ions based upon differences in the magnitude of the time-averaged field, where the average for each ion is taken over its transit time.

18 . The TOF mass spectrometer of claim 16 ,
wherein the rotating electric field separates ions in the accelerated beam by electric deflection so that at any given instant of time the ions of the accelerated beam are arranged in a spiral pattern on the two-dimensional detector, and wherein ions of increasing mass-to-charge ratio are separated monotonically along the spiral pattern inward toward the center of the spiral pattern.

19 . The TOF mass spectrometer of claim 16 ,
wherein the mass range of separated ions that is recorded by the two-dimensional detector and the mass resolving power of the two-dimensional detector are determined by the following operating parameters: the kinetic energy per charge applied by the accelerator, the period of the rotating electric field, the field strength of the rotating electric field, the length of the region over which the electric field is applied, and the distance between the deflector and the two-dimensional detector.

20 . The TOF mass spectrometer of claim 16 ,
wherein the operating parameters are chosen to provide a separation of adjacent rings in the spiral pattern in which separated ions are arranged on the two-dimensional detector at any given instant of time no smaller than the diameter of the focused beam on the two-dimensional detector.

21 . The TOF mass spectrometer of claim 16 ,
a processor in communication with the accelerator, the deflector, and the two-dimensional detector that
receives an arrival time and a two-dimensional arrival position for each ion impacting the two-dimensional detector and
calculates a time-of-flight for each ion impacting the two-dimensional detector from the arrival time and the two-dimensional arrival position.

22 . The TOF mass spectrometer of claim 16 ,
wherein the processor calculates a time-of-flight for each ion impacting the two-dimensi

Assignees

• Dh Technologies Dev Pte Ltd

Inventors

• Grothe Jr Robert Alois

Classifications

• H01J49/025

  Detectors specially adapted to particle spectrometers (data acquisition H01J49/0036; detectors per se G01T, e.g. G01T1/28, G01T1/29) · CPC title

• H01J49/40 Primary

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

• H01J49/22

  Electrostatic deflection · CPC title

• H01J49/20

  Magnetic deflection · CPC title

• H01J49/0031

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