Cascaded-Signal-Intensifier-Based Ion Imaging Detector for Mass Spectrometer

Patent metadata

Field	Value
Publication number	US-2016172173-A1
Application number	US-201414567744-A
Country	US
Kind code	A1
Filing date	Dec 11, 2014
Priority date	Dec 11, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

A detector system for a mass spectrometer comprises: a metal channel dynode (MCD) comprising at least one perforated metal plate configured to receive the exiting ions and eject electrons in response; a plurality of electron-to-photon converters arranged in a parallel stacked configuration, each such converter comprising a substrate plate having a phosphor coating on a first face; and an electrode film disposed on the phosphor coating; at least one photocathode, each of the at least one photocathode disposed between a respective pair of the plurality of electron-to-photon converters; an optical detector optically coupled a last one of the electron-to-photon converters; and at least one direct current power supply configured to apply, in operation, a respective bias electrical potential to the MCD and each of the electrode films and photocathodes.

First claim

1 . A detector system for a mass spectrometer for detecting time-dependent two-dimensional distributions of ions that exit a mass analyzer of the mass spectrometer, the detector system comprising:
(a) a metal channel dynode (MCD) comprising at least one perforated metal plate and configured to receive the exiting ions and eject electrons in response thereto; (b) a plurality of electron-to-photon converters, each comprising:
(b1) a substrate plate comprising first and second parallel faces;
(b2) a phosphor coating on the first face of the substrate plate; and
(b3) an electrode film disposed on the phosphor coating,
wherein the electron-to-photon converters are arranged in a parallel stacked configuration such that the electrode film of the substrate plate of a first one of the electron-to-photon converters faces the MCD and such that the electrode film of every succeeding electron-to-photon converter faces the second face of the substrate plate of the respective preceding electron-to-photon converter;
(c) at least one photocathode, each of the at least one photocathode disposed between a respective pair of the plurality of electron-to-photon converters; (d) an optical detector optically coupled a last one of the electron-to-photon converters; and (e) at least one direct current (DC) power supply configured to apply, in operation, a respective bias electrical potential to the MCD and each of the electrode films and photocathodes.

2 .- 3 . (canceled)

4 . A detector system as recited in claim 1 , wherein the MCD comprises a perforated metal plate having parallel first and second faces and in which the perforations comprise slots through the plate that slope at an angle to the parallel plate faces.

5 . A detector system as recited in claim 1 , wherein the MCD comprises a plurality of perforated metal plates arranged in a stacked arrangement such that the perforations of each succeeding plate are laterally offset from the perforations of the respective preceding plate.

6 .- 10 . (canceled)

11 . A detector system as recited in claim 1 , further comprising:
(f) at least one grid electrode, each of the at least one grid electrode disposed between a respective pair of the plurality of electron-to-photon converters.

12 . A detector system as recited in claim 1 , further comprising:
(f) at least one plate or film comprising an optically semi-reflective material that is transparent to electrons, each the at least one plate or film disposed between a respective pair of the plurality of electron-to-photon converters.

13 . (canceled)

14 . A detector system for a mass spectrometer for detecting time-dependent two-dimensional distributions of ions that exit a mass analyzer of the mass spectrometer, the detector system comprising:
(a) a metal channel dynode (MCD) disposed within a high vacuum chamber of the mass spectrometer, said vacuum chamber comprising a wall having an aperture therethrough, said MCD comprising at least one perforated metal plate and configured to receive the exiting ions and eject electrons in response thereto; (b) at least one direct current (DC) power supply electrically coupled to the MCD; (c) an optically transparent plate or wall disposed against the vacuum chamber wall aperture and forming a vacuum seal therewith; (d) a phosphor coating disposed on the transparent plate or wall and within the vacuum chamber so as to receive the ejected electrons; (e) an image intensifier optically coupled to the transparent plate or wall so as to receive a quantity of photons generated at the phosphor coating and to emit an amplified quantity of photons proportionate to the quantity of photons; and (f) an optical detector optically coupled the image intensifier and configured so as to receive the amplified quantity of photons.

15 . A detector system as recited in claim 14 , further comprising:
(g) a lens assembly providing the optical coupling between the image intensifier and the optical detector.

16 . A detector system as recited in claim 14 , wherein the MCD comprises a shadow mask.

17 - 18 . (canceled)

19 . A detector system as recited in claim 14 , wherein the MCD is coated with a metal oxide enhancer.

20 . (canceled)

21 . A detector system as recited in claim 14 , wherein the image intensifier includes an evacuated housing and the optically transparent plate or wall comprises a portion of the housing.

22 . A detector system as recited in claim 14 , wherein the image intensifier (e) comprises:
(e1) at least, one photocathode electrically coupled to the at least one DC power supply, one photocathode of the at least one photocathode optically coupled to the optically transparent plate or wall so as to receive the quantity of photons generated at the phosphor coating and to emit a proportionate quantity electrons in response thereto; and (e2) at least one electron-to-photon converter comprising:
(e2a) a substrate plate comprising first and second parallel faces;
(e2b) a phosphor coating on the first face of the substrate plate; and
(e2c) an electrode film disposed on the phosphor coating and electrically coupled to the at least one DC power supply,
wherein the phosphor is configured to receive the quantity of electrons or a different quantity of electrons generated within the image intensifier and to emit the amplified quantity of photons in response thereto.

23 .- 24 . (canceled)

25 . A detector system for a mass spectrometer for detecting time-dependent two-dimensional distributions of ions that exit a mass analyzer of the mass spectrometer, the detector system comprising:
(a) a metal channel dynode (MCD) comprising at least one perforated metal plate and configured to receive the exiting ions and eject electrons in response thereto; (b) a substrate plate comprising a first surface facing the MCD and a second surface; (c) a phosphor coating on the first surface of the substrate plate configured so as to receive the ejected electrons and to emit a proportionate quantity of photons in response thereto; (d) an electrode film disposed on the phosphor coating; (e) at least one direct current (DC) power supply configured to apply, in operation, a respective bias electrical potential to the MCD and the electrode film; and (e) an optical detector comprising a two-dimensional array of silicon photomultipliers optically coupled to the substrate plate so as to receive the quantity of photons.

26 - 30 . (canceled)

31 . A detector system as recited in claim 25 , wherein the substrate plate comprises a fiber-optic plate comprising a bundle of optical fibers.

32 . A detector system as recited in claim 25 , wherein substrate plate comprises a mica plate.

33 . A method of for detecting a two-dimensional distribution of ions exit from a mass analyzer of a mass spectrometer, comprising:
(a) intercepting the ions by a metal channel dynode (MCD) such that a two dimensional distribution of electrons is emitted by the MCD, wherein a quantity of the emitted electrons emitted at each portion of the MCD is proportionate to a quantity of the ions intercepted by each said respective portion; (b) intercepting the two-dimensional distribution of electrons emitted by the MCD by an electron-to-photon converter, such that a two dimensional distribution of photons is emitted by the electron-to-photon converter, wherein a quantity of the emitted photons emitted at each portion of the electron-to-photon converter is proportionate to a quantity of the el

Assignees

• Thermo Finnigan Llc

Inventors

• Schoen Alan E
• Smith Johnathan Wayne

Classifications

• H01J49/4215

  Quadrupole mass filters (H01J49/4225 takes precedence) · CPC title

• H01J49/025 Primary

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

• H01J43/045

  Position sensitive electron multipliers · CPC title

• H01J49/0031

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

• H01J49/027 Primary

  detecting image current induced by the movement of charged particles (H01J49/38 takes precedence) · CPC title