EP0125950B1 - Perfectionnements apportés aux spectromètres de masse - Google Patents

Perfectionnements apportés aux spectromètres de masse Download PDF

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Publication number
EP0125950B1
EP0125950B1 EP84400707A EP84400707A EP0125950B1 EP 0125950 B1 EP0125950 B1 EP 0125950B1 EP 84400707 A EP84400707 A EP 84400707A EP 84400707 A EP84400707 A EP 84400707A EP 0125950 B1 EP0125950 B1 EP 0125950B1
Authority
EP
European Patent Office
Prior art keywords
ions
magnetic sector
spectrometer
order
vessel
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP84400707A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0125950A2 (fr
EP0125950A3 (en
Inventor
Georges Slodzian
Jean-Claude Lorin
Roger Dennebouy
Marcel Chaintreau
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cameca SAS
Original Assignee
Cameca SAS
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 Cameca SAS filed Critical Cameca SAS
Publication of EP0125950A2 publication Critical patent/EP0125950A2/fr
Publication of EP0125950A3 publication Critical patent/EP0125950A3/fr
Application granted granted Critical
Publication of EP0125950B1 publication Critical patent/EP0125950B1/fr
Expired legal-status Critical Current

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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
    • H01J49/30—Static spectrometers using magnetic analysers, e.g. Dempster spectrometer
    • 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
    • H01J49/326—Static spectrometers using double focusing with magnetic and electrostatic sectors of 90 degrees

Definitions

  • the present invention relates to a mass spectrometer comprising an ion source, means of acceleration capable of imparting to the ions an energy essentially dependent on their electric charge, means for establishing in a sector a magnetic field orthogonal to the plane of the trajectory of the ions to curve this trajectory, and means for detecting ions.
  • a mass scan can be carried out using a mass spectrometer conforming to that described for example in French patent application No. 2,015,813 which allows frequent switching from one isotope to another or from one element to another if we want to obtain the precise value of a ratio.
  • Such mass scanning would be superfluous if the spectrometer were provided with multiple outputs allowing the simultaneous collection, on separate detectors, of several ionic species.
  • multiple output spectrometers are generally designed for particular applications so that it is often difficult, or even impossible without structural transformation, to change the nature of the few elements initially provided; these multiple output spectrometers are also expensive.
  • Mass scanning therefore remains the most widespread solution and makes it possible to work, at different times, on isotopes of different masses, with a scan fast enough in time to attenuate the drift of the ion source. .
  • the arrival energy of the detector ion is poorly controlled, which makes the measurements of the isotopic abundance ratios imprecise.
  • the main object of the invention is to provide a mass spectrometer in which mass scanning can be carried out precisely and quickly.
  • the ions after having been accelerated by the acceleration means and after having received a determined energy, describe their trajectory, under vacuum, in a metallic enclosure brought to the potential of the mass;
  • the means suitable for modifying the tangential speed of the ions can comprise a metallic envelope with a closed transverse contour, open at its two ends, and the mean line of which corresponds to the trajectory provided for the ions, this envelope being placed in the magnetic field and s spreading from the entry of the magnetic sector at the exit of this sector, and being brought to the same electrical potential as transverse electrodes located at the entry of the envelope and suitable for creating an electrostatic field of acceleration or tangential braking , essentially parallel to the direction of the speed of the ions at the entry of this envelope.
  • This insulated metal envelope placed in the electromagnetic field, that is to say between the poles of the electromagnet, makes it possible to maintain the poles of the magnet with the mass, without this resulting an influence on the ions whose energy, modified at the entry of the magnetic field, remains constant in this field.
  • the electric voltage intended to create the electrostatic field of tangential acceleration, at the entrance of the magnetic sector could be directly applied to the poles of the magnet.
  • the electric voltage intended to create a tangential acceleration (positive or negative) at the input of the magnetic sector is of the order of a few hundred volts, so that the control of variations in this voltage can be carried out more precise and faster than for much higher voltage. Voltage increments can be as low as 15 millivolts, which allows for great line pointing accuracy.
  • the invention advantageously applies to mass spectrometers with double focusing.
  • the objective of which is to allow the precise measurement of the isotopic abundance ratios with a mass spectrometer and more particularly with a mass spectrometer of the ion analyzer type, generally with double focusing.
  • the ions are produced by a phenomenon of secondary ion emission, that is to say that a sample of the material to be analyzed is bombarded with ions; this bombardment causes the ejection of ions characteristic of the material to be analyzed.
  • the analysis performed by the spectrometer relates to these ejected ions.
  • the ions thus ejected have a fairly large energy dispersion at the start of the target (formed by the material to be analyzed); this energy dispersion is much higher than that which exists when the ions are emitted by thermionic effect.
  • the phenomenon of secondary ion emission pro combines both polyatomic ions and simple ions which can have neighboring masses.
  • magnesium has three isotopes 24 Mg, 25 Mg, 26 Mg; the vacuum, bombardment conditions or the very nature of the sample mean that there are often ions of the MgH + type which are superimposed on the ions of the Mg + type.
  • Derivatives of the ion source require a mass scan which makes it possible to pass frequently from one isotope to another or from one element to another if one wants to obtain the precise value of a ratio.
  • the invention specifically proposes to improve this mass scanning.
  • This spectrometer comprises an ion source 1 operating according to the phenomenon of secondary ion emission.
  • This source 1 comprises a target 2 formed by a sample of the material to be analyzed, which is bombarded by ions coming from a source not shown.
  • the entire mass spectrometer is in a closed enclosure, not shown, in which a sufficient vacuum has been established.
  • Acceleration means A are adapted to communicate to the ions ejected from the target 2 an energy essentially dependent on their electrical charge.
  • These means A comprise an electrode E situated in a plane perpendicular to the direction A of the movement of the ions. This electrode E is brought, relative to the target 2 to a potential communicating the desired energy to the ions.
  • the acceleration electrostatic field between electrode E and target 2 is parallel to the path of the ions.
  • the electrode E can be brought to the ground potential, in which case the target 2 is brought to a positive potential if Ion wishes to accelerate positive ions, or to a negative potential for negative ions.
  • the acceleration potential is of the order of several thousand volts, for example of the order of 4000 volts.
  • the ions after being accelerated, circulate in a metallic tubular enclosure 3 brought to the same potential as the electrode E and serving as protection.
  • the ion beam passes through a first electrostatic optic 4 and passes through an inlet diaphragm 5 then enters an electrostatic sector 6 between two concentric curved walls 7 and 8, brought to different potentials so that the electrostatic field in sector 6 is oriented radially.
  • This electrostatic sector produces a first focusing of the ions at the opening 9 of a second diaphragm 10.
  • the direction of the trajectory of the ions, at the exit of the electrostatic sector 6, has turned by a certain angle relative to its direction of entry, this angle being 90 ° in the example of FIG. 1.
  • Means formed by an electromagnet of which a pole 11 is schematically represented, are provided for establishing in a magnetic sector 12 a magnetic field orthogonal to the plane of the path of the ions, that is to say orthogonal to the plane of the Figure 1, suitable for bending the trajectory of the ions.
  • An electrostatic coupling lens 13 is provided between the electrostatic sector 6 and the magnetic sector 12.
  • Selection slots 14 are provided in the focusing zone created by the magnetic sector 12.
  • Ion detection means comprise a detection system 15 located downstream of a collecting lens 16.
  • the spectrometer comprises, at the input 17 of the magnetic sector 12 electrostatic means 18 suitable for modifying the tangential speed of the ions and therefore their energy, in such a way that ions of different masses can, at different instants, follow the same curved trajectory in the magnetic sector 12.
  • the fixed magnetic field, in sector 12 is adjusted so as to address the isotope 25 in the middle of the slot 14. If we also want to address the isotope 25 Mg, but the 24 Mg isotope in the middle of the slot 14, in accordance with the invention, without modifying the magnetic field, the ions are accelerated positively along the direction of their trajectory 17 in sector 12 of such so that the 24 Mg isotope can rotate along the same trajectory as that previously followed by the 25 Mg isotope.
  • the ions, at the input 17, are subjected to a negative acceleration, that is to say braking along the direction of their trajectory, so that the 26 Mg isotope follows the same trajectory as that previously followed by the isotope 2 5Mg.
  • Electrostatic means 19 are provided at the outlet 20 of the sector 12 to cancel the modification of energy introduced by the means 18. In other words, if the means 18 have positively accelerated the ions at the entry, the means 19 exert braking to return these ions to their initial energy, and conversely, if the means 18 have exerted a braking, the means 19 exert an acceleration.
  • the means 18 comprise a metallic envelope 21, in particular of copper coated with gold, with closed transverse contour (see FIG. 4), open at its two ends 22, 23, and the mean line of which corresponds to the trajectory provided for the ions in sector 12.
  • This envelope 21 is placed in the magnetic field and extends from the input 17 to the output 20 of sector 12.
  • This envelope 21 is brought to the same electrical potential as transverse metal electrodes or plates 24, connected to this envelope, and located at the entrance 17 of sector 12.
  • These plates 24 are located opposite other transverse plates 25 of the end of the tubular enclosure 3 and brought to the same potential as this enclosure 3, it is ie at the potential of the mass or potential 0.
  • the plates 24 and 25 are located in planes orthogonal to the mean direction of the trajectory of the ions at the level of these plates and form electrodes whose axis is aligned on that of the ion beam.
  • the electric field between these plates is oriented parallel to the axis of the beam.
  • the means 19 comprise other transverse plates, or electrodes, 26 provided at the end 23 of the envelope. These plates 26 are at the same potential as the envelope 21 and as the plates 24. Plates 27, at ground potential, are located opposite the plates 26, the planes of these plates being perpendicular to the axis of the beam d ions leaving sector 12. The electric field created between the plates 26 and 27 exerts an opposite effect, but of the same amplitude, as that produced by the plates 24, 25.
  • the plates 27 are integral with a metallic tubular screen e which is at the same potential as the plates 27 and which extends to the detection system.
  • the metal casing 21 protects the electrically charged ions in the magnetic sector 12 against external parasitic electrostatic influences. Therefore, the poles such as 11 of the electromagnet can be at ground potential without disadvantage.
  • the poles such as 11 of the electromagnet could be brought to the potential of the plates 24 and 26, in which case the metal casing 21 could be eliminated.
  • the cross section 28 (FIG. 4) of this casing is given a flattened shape, substantially in diamond shape, the major axis of which is located in the mediating plane of the air gap field, while the minor axis is located halfway across the air gap.
  • the lateral edges 28a, 28b of the envelope, which are radially spaced from the trajectory of interest, are more distant from the poles of the electromagnet than the central part 28c of the envelope 21; this results in a reduction in the stray capacitance which limits the switching time of the voltages applied to the envelope 21.
  • This envelope 21 advantageously includes, in its wall, steps 29 (FIG. 3) so that baffles are formed inside the envelope 21 to stop the ions whose masses are different from that at which one s' is of particular interest.
  • the magnetic poles 11 a, and the magnetic sector 12a may have a shape substantially in Y, constituted by two arcs of a circle 30, 31, turning their convexity towards one another, tangent at one end and symmetrical to one another with respect to the tangent.
  • One of the branches, formed by the arc 30 situated on the left of the representation of FIG. 3, is used for the mass spectrometer itself, while the other branch 31 is intended for a viewing device combined with the spectrometer massive.
  • the casing 21a preferably, a shape similar to that of the magnetic sector 12a and comprises two branches in an arc 30a, 31a, connecting to the common end 32a. Only the branch 30a intervening in the part of the spectrometer used for the ionic analyzer comprises the steps 29. The presence of the branch 31a makes it possible to avoid parasitic phenomena, in particular distortions on the image observed in this part of the apparatus.
  • the optical properties of the acceleration and braking spaces can be taken into account as well as their deleterious effects on the double focusing.
  • Small “multipoles” and in particular “quadrupoles 33, 34 suitably placed at the input and / or at the output of the magnetic sector make it possible to correct these parasitic effects. Voltages of a few volts are sufficient so that there is no difficulty in programming the quasi-simultaneous application of the voltage on the envelope 21 and of the voltages on the quadrupoles 33, 34.
  • the quadrupole 33 is formed by four rectangular metal plates arranged along the faces of a rectangular parallelepiped (see Figure 5); the opposing plates two by two are brought to the same potential; the neighboring plates located in orthogonal planes are therefore at different potentials.
  • the fixed value of the magnetic field does not have to be exactly set for a particular isotope to pass through the slots 14; this adjustment can be made directly by means of the voltage “v applied to the metal casing 21.
  • the precision of the pointing of a line greatly exceeds the resolution in mass; indeed, an AM / 10- 5 M is detectable. This precision can be used to determine exactly the nature of a polyatomic ion; it can also be used to address the lines in the middle of the selection slot 14; we can then give the latter the optimal width compatible with the elimination of the interfering ion and with a precise measurement of the intensity of the line because the risks of cutting by the lips of the slot are then minimized.
  • FIG. 2 shows an alternative embodiment according to which the magnetic sector 12 is located upstream of the electrostatic sector 6.
  • the same reference numerals as those in FIG. 1 are used, in FIG. 2, to designate identical or similar elements.

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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)
EP84400707A 1983-04-19 1984-04-10 Perfectionnements apportés aux spectromètres de masse Expired EP0125950B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8306375A FR2544914B1 (fr) 1983-04-19 1983-04-19 Perfectionnements apportes aux spectrometres de masse
FR8306375 1983-04-19

Publications (3)

Publication Number Publication Date
EP0125950A2 EP0125950A2 (fr) 1984-11-21
EP0125950A3 EP0125950A3 (en) 1986-04-23
EP0125950B1 true EP0125950B1 (fr) 1989-11-02

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Application Number Title Priority Date Filing Date
EP84400707A Expired EP0125950B1 (fr) 1983-04-19 1984-04-10 Perfectionnements apportés aux spectromètres de masse

Country Status (5)

Country Link
US (1) US4672204A (enrdf_load_stackoverflow)
EP (1) EP0125950B1 (enrdf_load_stackoverflow)
JP (1) JPS59205142A (enrdf_load_stackoverflow)
DE (1) DE3480366D1 (enrdf_load_stackoverflow)
FR (1) FR2544914B1 (enrdf_load_stackoverflow)

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6477853A (en) * 1987-09-18 1989-03-23 Jeol Ltd Mapping type ion microanalyzer
GB8912580D0 (en) * 1989-06-01 1989-07-19 Vg Instr Group Charged particle energy analyzer and mass spectrometer incorporating it
US5128543A (en) * 1989-10-23 1992-07-07 Charles Evans & Associates Particle analyzer apparatus and method
FR2666171B1 (fr) * 1990-08-24 1992-10-16 Cameca Spectrometre de masse stigmatique a haute transmission.
GB9019560D0 (en) * 1990-09-07 1990-10-24 Vg Instr Group Method and apparatus for mass spectrometry
GB9026777D0 (en) * 1990-12-10 1991-01-30 Vg Instr Group Mass spectrometer with electrostatic energy filter
GB9105073D0 (en) * 1991-03-11 1991-04-24 Vg Instr Group Isotopic-ratio plasma mass spectrometer
DE4228190A1 (de) * 1992-08-25 1994-03-03 Specs Ges Fuer Oberflaechenana Analysator für geladene Teilchen
RU2133519C1 (ru) * 1997-06-25 1999-07-20 Шеретов Эрнст Пантелеймонович Способ ввода анализируемых ионов в рабочий объем анализатора гиперболоидного масс-спектрометра типа трехмерной ловушки
GB0116676D0 (en) 2001-07-07 2001-08-29 Eaton Corp Synchronizer
WO2004047143A1 (en) * 2002-11-15 2004-06-03 Micromass Uk Limited Mass spectrometer
EP1517353B1 (en) * 2003-09-11 2008-06-25 ICT Integrated Circuit Testing Gesellschaft für Halbleiterprüftechnik mbH Charged particle beam energy width reduction system for charged particle beam system
WO2005088671A2 (en) * 2004-03-05 2005-09-22 Oi Corporation Gas chromatograph and mass spectrometer
FR2942072B1 (fr) * 2009-02-06 2011-11-25 Cameca Spectrometre de masse magnetique achromatique a double focalisation.
GB2521579B (en) * 2012-10-10 2018-12-19 California Inst Of Techn Mass spectrometer, system and use of the mass spectrometer for determining isotopic anatomy of compounds
EP2988118A1 (en) * 2014-08-22 2016-02-24 MB Scientific AB Neutral atom or molecule detector
WO2017075470A1 (en) * 2015-10-28 2017-05-04 Duke University Mass spectrometers having segmented electrodes and associated methods

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3231735A (en) * 1959-06-11 1966-01-25 John L Peters Mass spectrometer leak detector with an accelerator section between plural analyzersand the method for using same
GB1263705A (en) * 1968-08-16 1972-02-16 Atomic Energy Authority Uk Improvements in or relating to mass spectrometers
FR2193253B1 (enrdf_load_stackoverflow) * 1972-07-21 1975-03-07 Cameca

Also Published As

Publication number Publication date
FR2544914A1 (fr) 1984-10-26
EP0125950A2 (fr) 1984-11-21
FR2544914B1 (fr) 1986-02-21
EP0125950A3 (en) 1986-04-23
DE3480366D1 (en) 1989-12-07
US4672204A (en) 1987-06-09
JPS59205142A (ja) 1984-11-20
JPH0378742B2 (enrdf_load_stackoverflow) 1991-12-16

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