Mass spectrometer

Patent metadata

Field	Value
Publication number	US-2016240364-A1
Application number	US-201514980824-A
Country	US
Kind code	A1
Filing date	Dec 28, 2015
Priority date	Feb 13, 2015
Publication date	Aug 18, 2016
Grant date	—

Abstract

A mass spectrometer includes: an ionization unit configured to ionize an analyte gas; a filter unit configured to allow passage of only a target ion which is a component of the analyte gas ionized in the ionization unit and which has a specific mass-to-charge ratio; and an ion detection unit configured to detect an ion detection value based on the target ion having passed through the filter unit, wherein the ion detection unit includes a Faraday electrode which includes an electrode portion disposed along a centerline of the filter unit and a bottom electrode provided at a position downstream of the electrode portion in a flow of the target ion, the electrode portion and the bottom electrode being connected to each other, a secondary electron multiplier provided to face the electrode portion with the centerline located therebetween, and a blocking portion connected to the bottom electrode.

First claim

What is claimed is:

1 . A mass spectrometer, comprising:
an ionization unit configured to ionize an analyte gas; a filter unit configured to allow passage of only a target ion which is a component of the analyte gas ionized in the ionization unit and which has a specific mass-to-charge ratio; and an ion detection unit configured to detect an ion detection value based on the target ion having passed through the filter unit, wherein the ion detection unit comprises
a Faraday electrode which comprises an electrode portion disposed along a centerline of the filter unit and a bottom electrode provided at a position downstream of the electrode portion in a flow of the target ion so as to intersect with the centerline, the electrode portion and the bottom electrode being connected to each other,
a secondary electron multiplier provided to face the electrode portion with the centerline located therebetween, and
a blocking portion connected to the bottom electrode and configured to block a photoelectron and reflected light traveling toward the secondary electron multiplier.

2 . The mass spectrometer according to claim 1 ,
wherein a height of the blocking portion is 10 or less times a distance between the blocking portion and a position which is on a periphery of an irradiated area where the bottom electrode is irradiated with vacuum ultraviolet light generated upon ionization of the analyte gas and which is the most away from the blocking portion.

3 . The mass spectrometer according to claim 1 ,
wherein a position at which the blocking portion and the bottom electrode are connected to each other is set at a boundary of an irradiated area where the bottom electrode is irradiated with vacuum ultraviolet light generated upon ionization of the analyte gas.

4 . The mass spectrometer according to claim 1 ,
wherein the ion detection unit further comprises another blocking portion provided on the bottom electrode to face the blocking portion with the centerline located therebetween.

5 . The mass spectrometer according to claim 1 , comprising
a returning portion provided to the blocking portion and projecting toward the centerline.

6 . The mass spectrometer according to claim 1 , comprising
a returning portion provided to the Faraday electrode on a blocking portion side and projecting toward the centerline.

7 . The mass spectrometer according to claim 1 ,
wherein the ion detection unit further comprises a magnet unit whose magnetic line of force pass across a space between the blocking portion and the Faraday electrode.

8 . The mass spectrometer according to claim 7 , wherein
the magnet unit is provided to have the magnetic line of force pass in parallel with a blocking surface of the blocking portion in such a direction that the secondary electron multiplier is located on the left of the magnetic line of force in a top view from a side of the filter unit.

9 . The mass spectrometer according to claim 8 ,
wherein a height of the blocking portion is 1.5 to 3 times a distance between the blocking portion and a position which is on a periphery of an irradiated area where the bottom electrode is irradiated with vacuum ultraviolet light generated upon ionization of the analyte gas and which is the most away from the blocking portion.

10 . The mass spectrometer according to claim 1 ,
wherein a portion of the filter unit or the blocking portion to be irradiated with vacuum ultraviolet light is colored in black, while retaining electrical conductivity.

Assignees

• Canon Anelva Corp

Inventors

• Nakamura Megumi
• Takizawa Yoshiyuki
• Sugiyama Masayuki
• Shimada Yuji
• Mita Hiroki

Classifications

• 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

• H01J49/4215 Primary

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

• H01J49/0422

  for gaseous samples (interfaces to gas chromatographs G01N30/7206) · CPC title