US3622781A - Mass spectrograph with double focusing - Google Patents

Mass spectrograph with double focusing Download PDF

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Publication number
US3622781A
US3622781A US32931A US3622781DA US3622781A US 3622781 A US3622781 A US 3622781A US 32931 A US32931 A US 32931A US 3622781D A US3622781D A US 3622781DA US 3622781 A US3622781 A US 3622781A
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Prior art keywords
mass spectrograph
field sector
energy
path
electronic lens
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Expired - Lifetime
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US32931A
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English (en)
Inventor
Helmut Liebl
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Institut fuer Plasmaphysik GmbH
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Institut fuer Plasmaphysik GmbH
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Priority claimed from DE19691938770 external-priority patent/DE1938770C3/de
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    • 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
    • H01J49/28—Static spectrometers
    • H01J49/32—Static spectrometers using double focusing
    • H01J49/322—Static spectrometers using double focusing with a magnetic sector of 90 degrees, e.g. Mattauch-Herzog type

Definitions

  • a beam-imaging means which may be a separate electronic lens, or part of the electric field sector deflection arrangement suitably energized, is located in advance of the beam energy aperture, by a distance such that the exit slit of the ion source is imaged in the plane of the beam energy aperture.
  • a second electronic lens is arranged between the beam energy aperture and the magnetic field sector deflection arrangement, of similar focal length, and arranged to image the target plane of the mass spectrograph at the same plane of the beam energy limiting means, so that the image focused thereon by the first imaging arrangement is received and focused on the target plane by the second electronic lens; the magnetic field sector deflection arrangement is rotated with respect to the electric field sector deflection arrangement by 180 to compensate for the effects of the lenses.
  • the presence of the lenses permits independent adjustment of dispersion an- 8 2 90555!
  • the present invention relates to a mass spectrograph in which the path of ions is so arranged that the ions are focused twice, in order to permit independent adjustment of the energy level ranges as well as of the angle of the beam.
  • Mass spectrographs of the Mattauch-l-lerzog type are widely used in industry and research. This type of mass spectrograph is distinguished from other types of mass spectrographs in that all particles can be focused simultaneously along a straight line-see, for example, H. Ewald and H. Hintenberger Methoden und füren der Massenspektroskopie," Chemieverlag Weinheim 1953.
  • the ions are focused twice, that is focusing is obtained by a double-focusing arrangement. lons which are introduced into the entrance slit in a predetermined, small angular range and which fall within a predetermined energy level, are focused to a mass spectrum as a first approximation.
  • Mass spectrographs of this type do, however, have the disadvantage that it is not possible to independently adjust the ranges of the angle and of the energy level. The reason is seen in that the entrance slit is placed in the focal length of the electrical sector field, so that ions of varying energy which leave the electrical sector field or the analyzer form differently oriented bundles of ions, the ions within the bundles themselves being parallel.
  • Spectrographs as referred to may limit the permitted range of the angle at the inlet side of the electrical sector field by a diaphragm opening.
  • An aperture or opening between the electrical and the magnetic sector field can limit the energy ranges of the ions.
  • This aperture may be referred to as an energy diaphragm, and it functions as a beam energy limiting means. The energy aperture however decreases the angular range of the ion beam and even if the energy aperture is infinitesimally small, ions which should be limited by the ion aperture can still pass therethrough.
  • both the angle and the energy range of the ions in the beam must be made small to avoid line spread at the image plane.
  • image aberrations of second order are present-see, for example, L. A. Kir'nig and H. Hintenberger, Nucl. Instr. 3, 133 (I958 One is the aperture aberration (a: aberration), the other the energy aberration (B aberration) and the third mixed aberration (a/Baberration). Of the three, the mixed (01B) aberration is the greatest.
  • both the aperture diaphragm as well as the energy aperture, or diaphragm must be made small, substantially decreasing the transmission of ions, that is decreasing their intensity, that is the overall ion energy, or ion current being applied to the target.
  • an electrical beam-imaging means is provided, such as an electrical lens.
  • An electronic lens is arranged behind the energy aperture by a distance equal to its focal length. The magnetic sector field follows this electronic lens and is so poled that the ions are deflected therein in the same sense as in the electrical sector field.
  • the beam-imaging means may wholly consist of the electrical sector field, which is then so formed and dimensioned that the ions are focused in the plane of the energy aperture.
  • the beam-imaging means may include an electronic lens located either between the entrance slit and the electrical sector field, or behind the electrical sector field, and designed and dimensioned to provide ion beams in which the ions of similar energy level are emitted in parallel, the further electronic lens being located the entrance side to the energy aperture by a distance equal to its focal length.
  • the focal lengths of one, or both of the electrical lenses are preferably adjustable, independently or conjointly.
  • FIG. 1 is a schematic presentation illustrating one example of the structure of the present invention
  • FIG. 2 is a presentation of the theoretical path of the beams in a portion of the mass spectrograph of FIG. 1;
  • FIG. 3 is a schematic presentation of a different embodiment of the present invention.
  • FIG. 4 is a schematic presentation of an arrangement in which the sector field images the entrance slit in the plane of the energy aperture.
  • the mass spectrograph of FIG. 1 has an entrance slit 10 to which ions are applied from an ion source 12, schematically indicated only, and known in the art.
  • the structure then includes: an aperture 14, located immediately in front of an electrical field sector deflection arrangement 16.
  • Behind the electrical field sector deflection means 16 is a first electronic lens assembly 18 which focuses ions into the plane of an energy aperture 20.
  • the ions emitted from the electrical sector field are parallel, but randomly oriented bundles of varying energy, which are now all focused on aperture 20.
  • the distance between energy aperture 20 and lens 18 is equal to the focal length f of the lens 18.
  • a second, electronic lens 22 located by a distance equal to its focal length from aperture 20, which preferably is the same as the focal length f of the first lens, is located behind the energy aperture 20 and which again restores the parallel relationships of the ion bundles.
  • the parallel ion bundles are then introduced into a magnetic field sector deflection means 24, which is limited at one of its end planes by an imaging plane 26, for example a photographic plate.
  • the mass spectrograph of the present invention thus differs from the known instruments of this type by the presence of the lenses 18, 22; additionally, the magnetic sector field 24 is rotated with respect to the mean entrance direction of the ions by l, so that the ions are deflected in opposite sense by the electrical and magnetic sector fields.
  • the two electrical lenses 18, 22 are located between the electrical sector field l6 and the magnetic sector field 24.
  • the first lens 18 images an intermediate image of the entrance slit 18 in its focal plane which is coincident with the plane of the energy aperture 20.
  • Ions of energy eU are focused at the axis of the energy aperture.
  • a positivesign indicates that the deflection in both cases would be in the same direction or sense, so that, by rotating one of the fields with respect to the other by 180, the structure of the system of FIG. 1 willmeet all mathematical requirements. All other parameters of the mass spectrograph, particularly those of the electrical and magnetic sector field may be dimensioned as is well known in apparatus of this type.
  • the energy aperture 20 will determine in the mass spectrograph in accordance with the present invention the energy level range independent of the beam aperture, due to the presence of the two lenses 18, 22, located symmetrically with respect to the opening of the energy aperture 20, in accordance with FIG. 1.
  • Introducing the two lenses 18, 22, has the further advantage that fine focusing and fine adjustment can be done entirely electrically.
  • Mass spectrographs of the above referred to type require additionally a mechanical displacement of the entrance slit in order to finefocus the beam.
  • Fine adjustment of energy focusing is done by moving the grounding point of the electrical sector field, which however, usually again changes the directional focusing. In mass spectrographs of the present invention, no mechanical motion of the entrance slit is necessary and energy focusing can beachieved as noted, independently of the directional focusing.
  • the intermediate image of the entrance slit 10 can be obtained by various arrangements. For example, it is possible to form the intermediate theoretical image solely by the electric sector field, as is being done by a known mass spectrograph see E. G. Johnson and AD. Nier, Phys. Rev. 91, I0 I953).
  • FIG. 3 An example is seen in which an imaging arrangement to obtain a theoretical intermediate image entrance slit 10 is shown. It includes an electric sector field l8, and an electronic lens 16' in advance thereof.
  • the relationship to obtain double focusing'for the case, in which only a single lens, namely the one in advance of the magnetic field, is located between the f... focal length of the lensin front of the magnetic sector K, exit dispersion coefficient of the electrical sector field I. angular dispersion coefficient of the electrical sector N, angle dispersion coefficient of the magnetic sector Reference is here also made to the above referred to publication by Konig and Hintenberger.
  • the lenses used consist of three cylindrical electrodes of equal inner diameter D, the length (thickness) of the central electrode being D/2,' and the distance between the center electrode and the outer electrode, each, being D/4.
  • a potential is applied to the center electrode of U A; 0.5 U (wherein U is the energy of the ion/electron discharge).
  • These two lenses are introduced between the electric and magnetic sector fields, with the energy aperture therebetween.
  • the distances between the electric and magnetic sector fields, at their final limits, are 24.6 cm., and the magnetic field is rotated by 180 about its exit direction.
  • lenses may be used, such as extended apertures which, analogous to optical cylindrical lenses focus in only one plane. They will then be so arranged that the focusing plane is coincident with the deflection plane of the mass spectrograph.
  • Focusing the electronic lenses 18, 22, can readily be accomplished by connecting the elements of the electronic lenses to a source of voltage, as schematically indicated in FIG.- 2.
  • Potentiometers 32, 38 are provided, connected to a source,
  • FIG. 4 illustrates an arrangement in which the sector field alone images the entrance slit in the plane of the energy aperture.
  • the mathematical relationships for double focusing are' identical to those discussed in connection with the embodiments of FIGS. 1 to 3, namely formula (7) is equally applicable.
  • angles and parameters are indicated in FIG. 4. These angles, and parameters, in accordance with a calculated example, may be as follows:
  • the toroidal condenser, and the axial effect of the lenses in combination with the slanting limits of the magnetic field results in focusing the ions also perpendicularly to the plane of the drawing (see for example: R. Herzog ActaPhys. Austriacae 4 (I950) p. 413).
  • the example of FIG. 4 illustrates that the image plane does not coincide with the trailing limit of the magnetic field, but rather forms an angle in therewith, which intersects at its origin with the intersection of the beam axis with the leading limit of the magnetic field.
  • Focusing of the lens 22 can, again, be readily accomplished by connecting the center electrode to a source of varying potential, for example to the tap point of a potentiometer.
  • Mass spectrograph comprising an ion source (12) generating a beam of ions
  • magnetic field sector deflection means (24) located in the path of said beam and magnetically deflecting said beam;
  • beam energy limiting means (20) located in the path of said beam and disposed between said electric and magnetic field sector deflection means; beams imaging means (16-18; 16'-l8') located between the entrances slit and the beam energy limiting means and focusing said beam, in its path, to image said entrance slit in the plane of the beam energy limiting means (20) and in advance of said magnetic field sector means (24);
  • an electric lens (22) located in the path of said beam in advance of said magnetic field sector deflection means spaced from said beam energy limiting means (20) by a distance equal to its focal length and energized to transform the beam entering said electronic lens (22) to a parallel beam so that the beam entering the magnetic field sector deflection means 24) is parallel;
  • said magnetic field sector deflection means (24) is poled and oriented to deflect said ions in the same sense and direction as said electric field sector deflection means l6).
  • Mass spectrograph according to claim 1, wherein the energy band path width of said beam energy limiting means (20) is adjustable.
  • Mass spectrograph according to claim 1, including a beam width limiting means (14) located between the entrance slit 10) and the beam-imaging means (l6, l8).
  • Mass spectrograph according to claim 3, wherein the beam pass width of said beam width limiting means 14) is adjustable.
  • Mass spectrograph according to claim 1, wherein said beam-imaging means comprises said electric field sector deflection means (16) and means energizing said deflection means to simultaneously deflect said ion beam and to focus the image of said slit by said beam in the plane of the beam energy limiting means (20).
  • Mass spectrograph according to claim 1, wherein said beam-imaging means comprises an electronic lens assembly (18) located behind said electric field sector deflection means (16) in the path of said beam, said electronic lens assembly being spaced from said beam energy limiting means (20) by a distance equal to the focal length (I) of the electronic lens assembly 18).
  • Mass spectrograph according to claim 1, wherein said beam imaging means comprises an electronic lens assembly (16) located in advance of said electric field sector deflection means (18) in the path of said beam.
  • Mass spectrograph according to claim 1, wherein the focal length of the electronic lens (22) located in advance of the magnetic field sector deflection means (24) is adjustable.
  • Mass spectrograph according to claim 1, wherein the focal length of said beam imaging means (16, 18) and said electronic lens (22) is adjustable;

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Tubes For Measurement (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
US32931A 1969-07-30 1970-04-29 Mass spectrograph with double focusing Expired - Lifetime US3622781A (en)

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DE19691938770 DE1938770C3 (de) 1969-07-30 Massenspektrograph mit Doppelfokussierung

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BE (1) BE749340A (cs)
FR (1) FR2056163A5 (cs)
GB (1) GB1320206A (cs)
LU (1) LU61429A1 (cs)
NL (1) NL7004207A (cs)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922544A (en) * 1972-09-01 1975-11-25 Strahlen Umweltforsch Gmbh Device for separation of sputtered neutrals and high energy ions from sputtered low energy ions
JPS5181693A (en) * 1975-01-16 1976-07-17 Ulvac Corp Ionchunyuyo shitsuryobunrisochi
JPS5240393A (en) * 1975-09-26 1977-03-29 Hitachi Ltd Mass spectrometer
EP0151078A3 (en) * 1984-01-27 1986-08-20 Office National D'etudes Et De Recherches Aerospatiales(O.N.E.R.A.) High intensity mass spectrometer with simultaneous multiple detection
US20050178982A1 (en) * 2004-02-17 2005-08-18 Fei Company Particle source with selectable beam current and energy spread
US20100224592A1 (en) * 2009-03-06 2010-09-09 Fei Company Charged particle beam processing
US7999225B2 (en) 2008-05-26 2011-08-16 Fei Company Charged particle source with integrated energy filter
US8796646B2 (en) 2010-06-30 2014-08-05 Fei Company Beam-induced deposition at cryogenic temperatures
US11081331B2 (en) * 2015-10-28 2021-08-03 Duke University Mass spectrometers having segmented electrodes and associated methods
CN118778494A (zh) * 2024-06-06 2024-10-15 中国核电工程有限公司 一种双聚焦质谱仪的电控系统、双聚焦质谱仪

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3014785C2 (de) 1980-04-17 1983-04-07 Leybold-Heraeus GmbH, 5000 Köln Monochromator für geladene Teilchen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3233099A (en) * 1963-09-16 1966-02-01 Cons Electrodynamics Corp Double-focusing mass spectrometer having electrically adjustable electrostatic an alyzer and adjustable electrostatic lens
US3487208A (en) * 1967-06-01 1969-12-30 Us Air Force Method of improving sensitivity and resolution of a mass spectrometer
US3524056A (en) * 1968-01-05 1970-08-11 Atomic Energy Commission Double focusing spectrograph employing a rotatable quadrupole lens to minimize doppler broadening

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3233099A (en) * 1963-09-16 1966-02-01 Cons Electrodynamics Corp Double-focusing mass spectrometer having electrically adjustable electrostatic an alyzer and adjustable electrostatic lens
US3487208A (en) * 1967-06-01 1969-12-30 Us Air Force Method of improving sensitivity and resolution of a mass spectrometer
US3524056A (en) * 1968-01-05 1970-08-11 Atomic Energy Commission Double focusing spectrograph employing a rotatable quadrupole lens to minimize doppler broadening

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922544A (en) * 1972-09-01 1975-11-25 Strahlen Umweltforsch Gmbh Device for separation of sputtered neutrals and high energy ions from sputtered low energy ions
JPS5181693A (en) * 1975-01-16 1976-07-17 Ulvac Corp Ionchunyuyo shitsuryobunrisochi
JPS5240393A (en) * 1975-09-26 1977-03-29 Hitachi Ltd Mass spectrometer
US4078176A (en) * 1975-09-26 1978-03-07 Hitachi, Ltd. Mass spectrometer
EP0151078A3 (en) * 1984-01-27 1986-08-20 Office National D'etudes Et De Recherches Aerospatiales(O.N.E.R.A.) High intensity mass spectrometer with simultaneous multiple detection
US4638160A (en) * 1984-01-27 1987-01-20 Office National D'etudes Et De Recherche Aerospatiales (Onera) High clarity mass spectrometer capable of multiple simultaneous detection
US20050178982A1 (en) * 2004-02-17 2005-08-18 Fei Company Particle source with selectable beam current and energy spread
US7034315B2 (en) * 2004-02-17 2006-04-25 Fei Company Particle source with selectable beam current and energy spread
US7999225B2 (en) 2008-05-26 2011-08-16 Fei Company Charged particle source with integrated energy filter
US8461525B2 (en) 2008-05-26 2013-06-11 Fei Company Charged particle source with integrated energy filter
US20100224592A1 (en) * 2009-03-06 2010-09-09 Fei Company Charged particle beam processing
US8598542B2 (en) 2009-03-06 2013-12-03 Fei Company Charged particle beam processing
US8796646B2 (en) 2010-06-30 2014-08-05 Fei Company Beam-induced deposition at cryogenic temperatures
US11081331B2 (en) * 2015-10-28 2021-08-03 Duke University Mass spectrometers having segmented electrodes and associated methods
CN118778494A (zh) * 2024-06-06 2024-10-15 中国核电工程有限公司 一种双聚焦质谱仪的电控系统、双聚焦质谱仪

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GB1320206A (en) 1973-06-13
NL7004207A (cs) 1971-02-02
BE749340A (fr) 1970-10-01
DE1938770A1 (de) 1971-02-18
FR2056163A5 (cs) 1971-05-14
LU61429A1 (cs) 1970-09-28
DE1938770B2 (de) 1976-10-21

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