US3582645A - Combined field and impact ionization source for mass spectrometers - Google Patents

Combined field and impact ionization source for mass spectrometers Download PDF

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Publication number
US3582645A
US3582645A US681256A US3582645DA US3582645A US 3582645 A US3582645 A US 3582645A US 681256 A US681256 A US 681256A US 3582645D A US3582645D A US 3582645DA US 3582645 A US3582645 A US 3582645A
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United States
Prior art keywords
field
ionization
impact
source
emitter electrode
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Expired - Lifetime
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US681256A
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English (en)
Inventor
Curt Brunnee
Kurt Elfenbein
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Finnigan MAT GmbH
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Varian Mat GmbH
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Assigned to FINNIGAN MAT GMBH reassignment FINNIGAN MAT GMBH ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: VARIAN MAT GMBH
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/10—Ion sources; Ion guns
    • H01J49/14—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers

Definitions

  • a combined field and impact ionization source includes a conducting housing embracing the trajectory of an electron beam for producing ions by impact.
  • the conducting housing includes an ion exit gap through which an electric field leads ions produced by impact to a mass spectrometer.
  • the conducting housing also functions as a counterelectrode that coacts with an emitter electrode of very small radius of curvature to comprise a field ionization source when the conducting housing is highly negative, such as 10 kilovolts, relative to the emitter electrode to produce ions by field ionization that are guided through the ion exit gap to the mass spectrometer.
  • the problem underlying the invention is to provide a combined field ion and electron impact ion source which enables ionization according to both procedures, of easily and also of difficultly vaporizable substances with the substance supply not having to be repositioned.
  • the emitter electrode of the field ion source is arranged in the impact chamber of the impact ion source and that the same exit gap with its metallic boundary wall serves as a boundary for the impact chamber when operating as an impact ion source and is switched to serve as the counterelectrode relative to the emitter electrode when operating as a field ion source, it being thereby achieved that the ionization zones for both kinds of ionization are spatially coincident or overlapping, and that for investigating difficultly vaporizable materials, the vaporization oven for these materials has to be provided only at one place, the expense for seals for the oven being thereby considerably lower. Moreover, one and the same specimen can be measured according to the one and the other procedure, during the vaporization procedure, simply by performing electrical switching operations outside the vacuum.
  • a particularly advantageous construction for the ion source is obtained if the counterelectrode is provided in known manner with a collar surrounding the emitter electrode, and has a window for entry of the electrons into the impact chamber when impact ionization is used.
  • the emitter electrode In order to avoid impairment of the emitter electrode during the impact ionization, due to impurities, it is advantageous to arrange the emitter electrode so that it can be withdrawn from the impact chamber.
  • the emitter electrode can be carried by a member having only a small surface, e.g. a swordlike body, which can be inserted with the electrode through an opening in the wall of the impact chamber housing opposite the outlet gap of the chamber, and also withdrawn.
  • a vaporization oven is connected in such a way that the ionization zone for the impact ionization and also the ionization zone for the field ionization lies in the vapor beam region of the vaporization oven.
  • the central beam direction of vaporization oven lies between the two ionization zones.
  • FIG. 1 is a diagrammatic view of an embodiment of an ion source according to the invention.
  • FIG. la is a partial section along the line 11-" of FIG. 1, and
  • FIG. 2 is a diagrammatic view of a second embodiment.
  • a device for impact ionization is combined with a device for field ionization.
  • Impact ionization and field ionization take place in the ion source according to FIG. 1 and 2, both in a common ionization chamber 1.
  • the impact ionization takes place by impacts of rapid electrons, which are emitted in the usual way by a glowing cathode 2 lying e.g. at +2900 v., and are accelerated by means ofa potential of v. between the cathode and the impact chamber, and pass through this on a trajectory 3.
  • the electrons After passing through the impact chamber 1, the electrons are intercepted by an interceptor 4.
  • the impact chamber 1 is surrounded by a metallic housing so as to form a defined electric field with low field gradients.
  • This housing is in the form of a box of essentially rectangular cross section, the longitudinal axis of which coincides with the trajectory 3 of the electrons. At the level of the trajectory 3, windows 5 and 6 are provided for passage of the electrons.
  • an exit gap 8 is provided in a longitudinal wall 7, hereafter called the front wall, in front of which, insulated from the box, a lens 9 is provided for extracting the ions from the box and for accelerating the ions in the direction 10 to the separation tube 11 of the mass spectrometer. Between the lens 9 and the separation tube 11, one or more diaphragms 12 are provided for accelerating and focusmg.
  • the box surrounding the impact chamber 1 consists of two parts, a cap-shaped part 14 with a rear wall 13 which borders the impact chamber 1 on five sides, and the sixth wall 7 which is separated and insulated therefrom, and which forms the front wall in which the exit slot 8 is provided.
  • the cap shaped part 14, designated box in the following, is at a potential of +3000 v., the acceleration voltage of 100 v. being established between the cathode 2 and the impact chamber 1, for the electrons.
  • the front wall 7 of the box is connected with a changeover switch 15 by which the front wall can be connected to a potential of +2995 v. for the operation as an impact ionization source, or for operation as a field ionization source can be connected to a potential of 9 kv.
  • the front wall 7 with its exit gap 8 serves by virtue of its small negative potential relative to the box 14 for reinforcing the lens 9, in order to move the ions formed by the electron impact in the box 1, in the direction 10 towards the separating tube 11. It should be noted that for impact ionization operation, the front wall 7 could be mechanically and electrically connected with the remainder of the box 14, since the penetration of the lens field -through the exit gap 8 can suffice to withdraw the ions from the impact chamber.
  • the front wall 7 with the exit gap 8 serves as a counter electrode to the emitter electrode 16 and as a withdrawal diaphragm for the field ions for moving these field ions in the direction 10 to the separation tube 11 of the mass spectrometer.
  • the emitter electrode 16 is disposed in the chamber 1 on the side of the trajectory 3 opposite the exit gap 8, for the impact ionization, so that with both kinds of ionization essentially the same ionization zone 17 results, which is shown by cross shading in the drawing.
  • the emitter electrode can consist of a very thin platinum wire arranged parallel to the trajectory 3 or to the exit gap 8, which is maintained at the same potential of +3000 v. as the box 14. With operation as a field ion source, a potential of l2 kv. exists between the emitter electrode 16 and the counterelectrode 17. Thus, in the region of the emitter electrode, as a result of its small radius of curvature, such a high field strength is achieved that in the vicinity of the emitter electrode, field ions are formed due to the socalled tunnel effect.
  • the counterelectrode 7 is provided with a collar 18 which extends around the emitter electrode 16, and which is provided in the vicinity of the trajectory 3 with windows 19, 20 for passage of the electrons when operating as an impact ion source.
  • the emitter electrode 16 is provided on a sword-shaped carrier 21 which extends from the outside through a slot 22 in the rear wall of the box 14 and which is carried by a lever 24 rockable about an axis 23.
  • a traction cable 38 which may be sealed relative to the housing, e.g. by a bellows, the lever arm 24 can be swung in order to withdraw the emitter electrode 16 out of the impact chamber 1 when operating the ion source as a pulse ion source, so as to avoid a gradual contamination of the emitter electrode 16 by electrons impinging thereon.
  • the second embodiment of the ion source according to the invention is illustrated.
  • the emitter electrode 16 as in the previously known combined impact ion and field ionization sources is disposed outside the impact chamber 1 for the impact ionization, and the counterelectrode 26 for the field ionization lies with its ion exit slot 27 in or in front of an opening 28 of the rear wall 13 of the impact chamber box 14.
  • This combined ion source thus has spatially separated ionization zones 29 and 30.
  • the oven 25 is so arranged that the ionization zone 29 for the field ionization and also the ionization zone 30 for the impact ionization lie in the vapor beam region 31 of the vaporization oven.
  • the oven is connected to the underside ofthe impact chamber box 14 in such a manner that the vapor beam passes through the central region of the electron trajectory 3 for the impact ionization and through the exit slot 27 of the counterelectrode 26 in the vicinity of the emitter electrode 16, for the field ionization.
  • the front wall 7 with the remainder of the box 14 could be maintained at the same potential of 3 kv. when operating as an impact ion source and also when operating as a field ion source.
  • the emitter electrode would have to be placed at a correspondingly higher potential of for example +12 kv.
  • the illustrated ion sources are suitable for the analysis of various substances.
  • a combined field and impact ionization source comprising,
  • an emitter electrode adjacent to said intermediate aperture for coaction with said conducting housing functioning as a counterelectrode comprising a field ionization source
  • a combined field and impact ionization source in accordance withclaim l and further comprising means for relatlvely positioning said conducting housing, said electron beam source and said emitter electrode so that the region of impact ionization is along said trajectory, and said emitter electrode and the region of field ionization are outside said conducting housing.
  • a combined field and impact ionization source in accordance with claim I wherein said conducting housing is formed with a collar surrounding at least a portion of the region between said housing and said emitter electrode.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Tubes For Measurement (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
US681256A 1966-11-19 1967-11-07 Combined field and impact ionization source for mass spectrometers Expired - Lifetime US3582645A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1598150A DE1598150C3 (de) 1966-11-19 1966-11-19 Ionenquelle für Massenspektrometer mit einer Feldionisierungseinrichtung und einer ElektronenstoBionisierungseinrichtung

Publications (1)

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US3582645A true US3582645A (en) 1971-06-01

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US681256A Expired - Lifetime US3582645A (en) 1966-11-19 1967-11-07 Combined field and impact ionization source for mass spectrometers

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US (1) US3582645A (enrdf_load_stackoverflow)
DE (1) DE1598150C3 (enrdf_load_stackoverflow)
GB (1) GB1152757A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3886365A (en) * 1973-08-27 1975-05-27 Hewlett Packard Co Multiconfiguration ionization source
US3992632A (en) * 1973-08-27 1976-11-16 Hewlett-Packard Company Multiconfiguration ionization source
US4005291A (en) * 1972-01-04 1977-01-25 Massachusetts Institute Of Technology Ionization method for mass spectrometry
USRE30171E (en) * 1973-08-27 1979-12-18 Hewlett-Packard Company Multiconfiguration ionization source
US20090206274A1 (en) * 2007-12-28 2009-08-20 Newaire, Inc. Multi-electrode negative ion generator
WO2009114291A3 (en) * 2008-03-14 2009-12-30 Research Triangle Institute Faraday cup array integrated with a readout ic and method for manufacture thereof

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3115591A (en) * 1959-06-22 1963-12-24 Atlas Werke Ag Ion source for mass spectrometer
US3274436A (en) * 1962-01-31 1966-09-20 Reich Gunter Ion source with selective hot or cold cathode
US3313934A (en) * 1963-02-19 1967-04-11 Atlas Meb & Analysentechnik G Field ion source for mass spectrometry with elongated emitter
US3405263A (en) * 1966-01-14 1968-10-08 Exxon Research Engineering Co Dual mass spectrometer ion source comprising field ionization and electron bombardment sources and the method of use

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3115591A (en) * 1959-06-22 1963-12-24 Atlas Werke Ag Ion source for mass spectrometer
US3274436A (en) * 1962-01-31 1966-09-20 Reich Gunter Ion source with selective hot or cold cathode
US3313934A (en) * 1963-02-19 1967-04-11 Atlas Meb & Analysentechnik G Field ion source for mass spectrometry with elongated emitter
US3405263A (en) * 1966-01-14 1968-10-08 Exxon Research Engineering Co Dual mass spectrometer ion source comprising field ionization and electron bombardment sources and the method of use

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005291A (en) * 1972-01-04 1977-01-25 Massachusetts Institute Of Technology Ionization method for mass spectrometry
US3886365A (en) * 1973-08-27 1975-05-27 Hewlett Packard Co Multiconfiguration ionization source
US3992632A (en) * 1973-08-27 1976-11-16 Hewlett-Packard Company Multiconfiguration ionization source
USRE30171E (en) * 1973-08-27 1979-12-18 Hewlett-Packard Company Multiconfiguration ionization source
US20090206274A1 (en) * 2007-12-28 2009-08-20 Newaire, Inc. Multi-electrode negative ion generator
US8017919B2 (en) * 2007-12-28 2011-09-13 Newaire, Inc. Multi-electrode negative ion generator
WO2009114291A3 (en) * 2008-03-14 2009-12-30 Research Triangle Institute Faraday cup array integrated with a readout ic and method for manufacture thereof
US20110031388A1 (en) * 2008-03-14 2011-02-10 Research Triangle Institute Faraday cup array integrated with a readout ic and method for manufacture thereof
US8866080B2 (en) 2008-03-14 2014-10-21 Research Triangle Institute Faraday cup array integrated with a readout IC and method for manufacture thereof

Also Published As

Publication number Publication date
DE1598150C3 (de) 1978-10-26
DE1598150A1 (de) 1971-01-28
DE1598150B2 (enrdf_load_stackoverflow) 1978-03-09
GB1152757A (en) 1969-05-21

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Owner name: FINNIGAN MAT GMBH, BARKHAUSEN-STRASSE 2, 2800 BREM

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:VARIAN MAT GMBH;REEL/FRAME:004068/0713

Effective date: 19820903