WO2003065403A2 - Quadrupole mass spectrometers - Google Patents

Quadrupole mass spectrometers Download PDF

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Publication number
WO2003065403A2
WO2003065403A2 PCT/GB2003/000316 GB0300316W WO03065403A2 WO 2003065403 A2 WO2003065403 A2 WO 2003065403A2 GB 0300316 W GB0300316 W GB 0300316W WO 03065403 A2 WO03065403 A2 WO 03065403A2
Authority
WO
WIPO (PCT)
Prior art keywords
electrodes
ratio
quadrupole mass
radius
mass spectrometer
Prior art date
Application number
PCT/GB2003/000316
Other languages
French (fr)
Other versions
WO2003065403A3 (en
Inventor
Stephen Taylor
John Raymond Gibson
Original Assignee
University Of Liverpool
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University Of Liverpool filed Critical University Of Liverpool
Priority to AU2003238422A priority Critical patent/AU2003238422A1/en
Publication of WO2003065403A2 publication Critical patent/WO2003065403A2/en
Publication of WO2003065403A3 publication Critical patent/WO2003065403A3/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/26—Mass spectrometers or separator tubes
    • H01J49/34—Dynamic spectrometers
    • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
    • H01J49/4205—Device types
    • H01J49/421—Mass filters, i.e. deviating unwanted ions without trapping
    • H01J49/4215—Quadrupole mass filters
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/26—Mass spectrometers or separator tubes
    • H01J49/34—Dynamic spectrometers
    • H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
    • H01J49/4205—Device types
    • H01J49/4255—Device types with particular constructional features

Definitions

  • This invention concerns improvements in and relating to quadrupole mass spectrometers.
  • Quadrupole mass spectrometers may be used for residual gas analysis in the semiconductor industry, typically to determine gases present after processing, in order to ensure a clean chamber. Quadrupole mass spectrometers may also be used in chemical processes to detect presence of toxic gases.
  • a quadrupole mass spectrometer generally comprises an ion source, a mass filter and an ion detector.
  • Conventionally circular section metal rods are used as the mass filter by being excited electrically. This electrical excitement produces a field that can be controlled to permit only ionised particles of interest to reach the ion detector.
  • Ions are produced by the ion source to ionise gas particles. These ionised gas particles travel towards the detector through the mass filter.
  • the mass filter electrodes are electrically excited by means of a combination of alternating and direct voltages to produce a variable field from the detector, which can be used to focus ionised gas particles onto the detector, which measures the charge collected or the current carried by the ions, from which pressure of gases can be determined.
  • r/r 0 is chosen to be in the range of 1.11 to 1.17 for optimum QMS performance. (Resolution is defined as m/ ⁇ m at 10 or 50% of the peak height and transmission is defined as the number of ions per unit of time passing successfully through the mass filter to the detector.)
  • the mass spectra peak resulting from a QMS should have a high, narrow peak and a small low mass tail, which are indicative of good transmission and resolution results.
  • An object of this invention is to provide an improved QMS capable of producing good transmission and resolution results.
  • a QMS have at least two sets of electrodes in series, each set of electrodes being arranged to have a different r/ro ratio.
  • a first preferred way, in which to achieve different r/r 0 ratios is to have the electrodes of one set of greater radius than those of the other set of electrodes, whilst maintaining the aperture radius (ro) substantially constant.
  • the electrodes of all sets preferably have the same radius (r) but the aperture radius (r 0 ) for each set is different.
  • the first set of electrodes may have a lower r/ro ratio than the second set of electrodes, although it is possible to arrange the sets of electrodes the other way round.
  • the r/r 0 ratio of one set of electrodes may be about 1.11 to 1.12 with the other set of electrodes having a higher r/ro ratio.
  • one set of electrodes, especially the first set will have an r/r 0 ratio of about 1.11 and the other set of electrodes, especially the second set, will have an r/ro ratio of about 1.14.
  • Figure 1 shows schematically a QMS according to a first aspect of the invention.
  • Figure 2 is a plot of transmission against mass of two QMS systems of different sizes set by r/rO value.
  • a QMS 10 comprises an ion source 12, two sets of four electrodes 14,16 and an ion detector 18. The two sets of electrodes 14,16 are arranged in series.
  • the electrodes of the first set are of circular section, each electrode having a radius r-i.
  • the electrodes of the second set are also of circular section and each has a radius r 2 .
  • the electrodes define an aperture or path for ions to travel to the detector and the aperture has a radius ro defined as half the distance between opposed electrodes.
  • the first set of electrodes has an r/ro ratio of about 1.11 and the second set of electrodes has a higher r/ro ratio, typically of about 1.14.
  • Figure 2 shows spectra peak shapes for sets of electrodes with different r/r 0 ratios, the solid line plot ratio being 1.14 and the broken line plot ratio being 1.11. As can be seen the peak position moves as the geometry changes but a
  • QMS with two sets of electrodes together should produce a narrower peak, i.e. improved resolution, as the combined peak should only be the part common to both.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Electron Tubes For Measurement (AREA)

Abstract

A quadrupole mass spectrometer (10) has at least two sets (14, 16) of electrodes in series, each set of electrodes being arranged to have a different r/ro ratio, wherein the r/ro ratio is that between the electrode radius (r) and the radius of the aperture between electrodes (ro).

Description

Title: Quadrupole mass spectrometers
DESCRIPTION
This invention concerns improvements in and relating to quadrupole mass spectrometers.
Quadrupole mass spectrometers may be used for residual gas analysis in the semiconductor industry, typically to determine gases present after processing, in order to ensure a clean chamber. Quadrupole mass spectrometers may also be used in chemical processes to detect presence of toxic gases.
A quadrupole mass spectrometer (QMS) generally comprises an ion source, a mass filter and an ion detector. Conventionally circular section metal rods are used as the mass filter by being excited electrically. This electrical excitement produces a field that can be controlled to permit only ionised particles of interest to reach the ion detector. Ions are produced by the ion source to ionise gas particles. These ionised gas particles travel towards the detector through the mass filter. The mass filter electrodes are electrically excited by means of a combination of alternating and direct voltages to produce a variable field from the detector, which can be used to focus ionised gas particles onto the detector, which measures the charge collected or the current carried by the ions, from which pressure of gases can be determined.
On the basis of computer modelling of QMSs it has been shown that the behaviour of QMS fabricated with circular section electrodes varies significantly with changes in electrode radius. In particular, QMS resolution, mass spectra peak and transmission through the QMS are all affected by the ratio of the electrode radius (r) to the radius of the aperture between the electrodes (r0).
Usually r/r0 is chosen to be in the range of 1.11 to 1.17 for optimum QMS performance. (Resolution is defined as m/Δm at 10 or 50% of the peak height and transmission is defined as the number of ions per unit of time passing successfully through the mass filter to the detector.)
Desirably, the mass spectra peak resulting from a QMS should have a high, narrow peak and a small low mass tail, which are indicative of good transmission and resolution results.
An object of this invention is to provide an improved QMS capable of producing good transmission and resolution results.
According to the invention it is proposed that a QMS have at least two sets of electrodes in series, each set of electrodes being arranged to have a different r/ro ratio.
A first preferred way, in which to achieve different r/r0 ratios is to have the electrodes of one set of greater radius than those of the other set of electrodes, whilst maintaining the aperture radius (ro) substantially constant.
Alternatively, the electrodes of all sets preferably have the same radius (r) but the aperture radius (r0) for each set is different.
The first set of electrodes may have a lower r/ro ratio than the second set of electrodes, although it is possible to arrange the sets of electrodes the other way round. The r/r0 ratio of one set of electrodes may be about 1.11 to 1.12 with the other set of electrodes having a higher r/ro ratio. In one preferred embodiment of the invention one set of electrodes, especially the first set, will have an r/r0 ratio of about 1.11 and the other set of electrodes, especially the second set, will have an r/ro ratio of about 1.14.
This invention will now be further described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 shows schematically a QMS according to a first aspect of the invention; and
Figure 2 is a plot of transmission against mass of two QMS systems of different sizes set by r/rO value.
Referring to the accompanying drawings, a QMS 10 comprises an ion source 12, two sets of four electrodes 14,16 and an ion detector 18. The two sets of electrodes 14,16 are arranged in series.
The electrodes of the first set are of circular section, each electrode having a radius r-i. The electrodes of the second set are also of circular section and each has a radius r2. The electrodes define an aperture or path for ions to travel to the detector and the aperture has a radius ro defined as half the distance between opposed electrodes. The first set of electrodes has an r/ro ratio of about 1.11 and the second set of electrodes has a higher r/ro ratio, typically of about 1.14.
Figure 2 shows spectra peak shapes for sets of electrodes with different r/r0 ratios, the solid line plot ratio being 1.14 and the broken line plot ratio being 1.11. As can be seen the peak position moves as the geometry changes but a
QMS with two sets of electrodes together should produce a narrower peak, i.e. improved resolution, as the combined peak should only be the part common to both.

Claims

Claims:
1. A quadrupole mass spectrometer having at least two sets of electrodes in series, each set of electrodes being arranged to have a different r/ro ratio, wherein the r/ro ratio is that between the electrode radius (r) and the radius of the aperture between electrodes (ro).
2. A quadrupole mass spectrometer as claimed in claim 1 , wherein the electrodes of one set have a greater radius than those of the other set of electrodes, whilst maintaining the aperture radius (ro) substantially constant.
3. A quadrupole mass spectrometer as claimed in claim 1 , wherein the electrodes of all sets have the same radius but the aperture radius for each set of electrodes is different.
4. A quadrupole mass spectrometer as claimed in claim 1, 2 or 3, wherein the first set of electrodes has a lower r/ro ratio than the second set of electrodes.
5. A quadrupole mass spectrometer as claimed in any one of claims 1 to 4, wherein the r/ro ratio of one set of electrodes is about 1.11 to 1.12 with the other set of electrodes having a higher r/r0 ratio.
6. A quadrupole mass spectrometer as claimed in claim 5, wherein one set of electrodes has an r/ro ratio of about 1.11 and another set of electrodes, has an r/r0 ratio of about 1.14.
7. A quadrupole mass spectrometer as claimed in claim 6, wherein the set of electrodes having the r/ro ratio of about 1.11 is the first set.
8. A quadrupole mass spectrometer as claimed in claim 6 or 7, wherein the set of electrodes having the r/r0 ratio of about 1.14 is the second set of electrodes.
9. A quadrupole mass spectrometer substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
PCT/GB2003/000316 2002-01-29 2003-01-28 Quadrupole mass spectrometers WO2003065403A2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003238422A AU2003238422A1 (en) 2002-01-29 2003-01-28 Quadrupole mass spectrometers

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0201914.9 2002-01-29
GBGB0201914.9A GB0201914D0 (en) 2002-01-29 2002-01-29 Improvements in and relating to quadrupole mass spectrometers

Publications (2)

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WO2003065403A2 true WO2003065403A2 (en) 2003-08-07
WO2003065403A3 WO2003065403A3 (en) 2003-09-25

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AU (1) AU2003238422A1 (en)
GB (1) GB0201914D0 (en)
WO (1) WO2003065403A2 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8551388B2 (en) 2008-09-05 2013-10-08 The University Of Liverpool Process
US9929003B2 (en) 2015-06-04 2018-03-27 Thermo Finnigan Llc Ion source filter

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4234791A (en) * 1978-11-13 1980-11-18 Research Corporation Tandem quadrupole mass spectrometer for selected ion fragmentation studies and low energy collision induced dissociator therefor
EP1109198A2 (en) * 1999-12-03 2001-06-20 Thermo Finnigan LLC Mass spectrometer system including a double ion guide interface and method of operation
JP2001307674A (en) * 2000-04-21 2001-11-02 Yokogawa Analytical Systems Inc Inductively coupled plasma mass spectroscope

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4234791A (en) * 1978-11-13 1980-11-18 Research Corporation Tandem quadrupole mass spectrometer for selected ion fragmentation studies and low energy collision induced dissociator therefor
EP1109198A2 (en) * 1999-12-03 2001-06-20 Thermo Finnigan LLC Mass spectrometer system including a double ion guide interface and method of operation
JP2001307674A (en) * 2000-04-21 2001-11-02 Yokogawa Analytical Systems Inc Inductively coupled plasma mass spectroscope

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
DOUGLAS D J ET AL: "COLLISIONAL FOCUSING EFFECTS IN RADIO FREQUENCY QUADRUPOLES" JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY, ELSEVIER SCIENCE INC., NEW YORK, NY, US, vol. 3, 1992, pages 398-408, XP000667302 ISSN: 1044-0305 *
PATENT ABSTRACTS OF JAPAN vol. 2002, no. 03, 3 April 2002 (2002-04-03) & JP 2001 307674 A (YOKOGAWA ANALYTICAL SYSTEMS INC), 2 November 2001 (2001-11-02) *
REUBEN A J ET AL: "Ion trajectories in exactly determined quadrupole fields" INTERNATIONAL JOURNAL OF MASS SPECTROMETRY AND ION PROCESSES, ELSEVIER SCIENTIFIC PUBLISHING CO. AMSTERDAM, NL, vol. 154, no. 1, 31 May 1996 (1996-05-31), pages 43-59, XP004036512 ISSN: 0168-1176 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8551388B2 (en) 2008-09-05 2013-10-08 The University Of Liverpool Process
US9929003B2 (en) 2015-06-04 2018-03-27 Thermo Finnigan Llc Ion source filter

Also Published As

Publication number Publication date
AU2003238422A1 (en) 2003-09-02
WO2003065403A3 (en) 2003-09-25
GB0201914D0 (en) 2002-03-13

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