EP0290712B1 - Mass spectrometer - Google Patents

Mass spectrometer Download PDF

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Publication number
EP0290712B1
EP0290712B1 EP19870890179 EP87890179A EP0290712B1 EP 0290712 B1 EP0290712 B1 EP 0290712B1 EP 19870890179 EP19870890179 EP 19870890179 EP 87890179 A EP87890179 A EP 87890179A EP 0290712 B1 EP0290712 B1 EP 0290712B1
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Prior art keywords
octopole
arrangement
mass spectrometer
ion source
arrangement according
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EP19870890179
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German (de)
French (fr)
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EP0290712A1 (en
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Johannes Dr. Villinger
Werner Dr. Federer
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V & F Analyse- und Messtechnik GmbH
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V & F Analyse- und Messtechnik 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
    • H01J49/06—Electron- or ion-optical arrangements
    • H01J49/062—Ion guides
    • H01J49/063—Multipole ion guides, e.g. quadrupoles, hexapoles

Definitions

  • the invention relates to a mass spectrometer arrangement with an ion source, an adjoining one, receiving a gas or gas mixture and an octopole arrangement with a high-frequency 8-pole field acting perpendicular to the main direction of movement of the primary ions supplied by the ion source surrounding reaction space, as well as a mass spectrometer quadrupole connected to the reaction space in the main movement direction of the low kinetic energy.
  • drift tube arrangements e.g. SIDT-Quasistatic Selected-lon Drift Tubes
  • the primary ions emerging from an exchangeable ion source entering an octopole storage zone can be used, for example, with a neutral gas or React gas mixture with production of new ions in known excitation states.
  • the ions From the octopole arrangement or the reaction space surrounding it, the ions enter the mass spectrometer quadrupole, where the type of ion to be investigated is selected in a known manner which is of no further interest here and then introduced into the actual drift chamber via a venturi-type inlet.
  • the arrangement described in the introduction can also be used directly as a mass spectrometer analyzer, in which case the gas mixture in the reaction space is examined by producing certain product ions with the primary ions which, after being selected in the mass spectrometer quadrupole, are immediately used as an ion detector can be supplied, which allows a mass spectrometric analysis in a known manner.
  • an extractor lens with a potential that is negative compared to the octopole arrangement is arranged after the reaction space in order to focus the ions from the reaction space into the mass spectrometer quadrupole. Under certain circumstances it would also be conceivable to place the quadrupole itself at a potential which is negative compared to the octopole arrangement.
  • the object of the present invention is to improve an arrangement of the type mentioned at the outset in such a way that the disadvantages of the known arrangements are avoided and in particular that the supply rate and supply speed of product ions formed in the reaction space to the mass spectrometer quadrupole are increased in a simple manner.
  • the octopole arrangement is divided in the longitudinal direction into individual regions which are electrically insulated from one another and which, viewed from the ion source to the mass spectrometer quadrupole, are each at a negative DC voltage potential which rises in relation to the previous region.
  • a DC voltage potential is generated at the nth octopole range, which is negative compared to the (n - 1) th range but positive compared to the (n + 1) th range.
  • a homogeneous electric field is generated in the axial direction to the mass spectrometer quadrupole, which serves as the driving force for the product ions. Since the random kinetic energy of the product ions is generally not greater than 1 eV, very low field strengths are sufficient, which reliably prevents disturbances of the mass spectrometer quadrupole due to high kinetic energies of the incoming product ions.
  • the total DC voltage effective at the octopole is in the range 5 to 30 V.
  • the direct voltage field strength at the octopole is uniformly 0.5 to 3 V / cm, preferably 1 V / cm.
  • the individual octopole regions are connected to a common DC voltage supply via a resistor chain, which enables a simple structure of the arrangement and enables a controlled field profile over the entire length of the octopole arrangement.
  • the mass spectrometer arrangement according to FIG. 1 has an ion source 1 of any design, not of interest here, a reaction space 2 connecting to the ion source 1, and a mass spectrometer connecting the primary ions supplied by the ion source 1 to the reaction space 2 in the main direction of movement z Quadrupole 3 on.
  • the reaction chamber 2, to which a gas or gas mixture can be supplied via a connection 4, is surrounded by an octopole arrangement 5 with a high-frequency 8-pole field acting perpendicular to the main direction of movement z of the primary ions, which is used for collection and mounting or guidance of the primary ions, which have a very low kinetic energy of typically below 100 eV.
  • the octopole arrangement 5 is in the longitudinal direction - that is, in the main direction of movement z of the primary ions emerging from the ion source 1 in a beam - into three individual Be electrically isolated from each other rich 7, 8, 9 divided, which - as seen from the ion source 1 to the mass spectrometer quadrupole 3 - are each at a negative DC voltage potential that increases in relation to the previous region.
  • This potential V eff counteracts the space charge pressure (Coulomb repulsion between the charges) of the ions which have only very low kinetic energy and thus keeps them in a cross section which is predetermined by the dimension of the octopole arrangement 5.
  • the division of the entire octopole arrangement 5, which can also be seen in FIG. 4, into three individual regions 7, 8, 9 which generate a direct current field which is superimposed on the high-frequency guide field, serves to separate the primary ions from the primary ions in collisions with the gas particles to bring product ions generated via the connection 4 supplied gas or gas mixture as quickly and completely as possible out of the reaction space 2 and to feed them to the mass spectrometer quadrupole 3 (FIG. 1) for selection or subsequent detection.
  • the total potential V Tot over the length of the octopole arrangement can be seen from FIG. 5.
  • the potential of the HF field is a parabolic trough, which is quasi raised by the - here uniform over the entire length - potential of the superimposed E field at the entrance of the octopole arrangement. From the illustration in FIG.

Description

Die Erfindung betrifft eine Massenspektrometer-Anordnung, mit einer lonenquelle, einem an diese anschließenden, ein Gas bzw. Gasgemisch aufnehmenden und von einer Oktopol-Anordnung mit einem senkrecht zur Hauptbewegungsrichtung der von der lonenqueile gelieferten Primär-Ionen wirkenden Hochfrequenz-8-Pol-Feld umgebenen Reaktionsraum, sowie einem in Hauptbewegungsrichtung der niedrige Bewegungsenergie aufweisenden Primär-Ionen an den Reaktionsraum anschließenden Massenspektrometer-Quadrupol.The invention relates to a mass spectrometer arrangement with an ion source, an adjoining one, receiving a gas or gas mixture and an octopole arrangement with a high-frequency 8-pole field acting perpendicular to the main direction of movement of the primary ions supplied by the ion source surrounding reaction space, as well as a mass spectrometer quadrupole connected to the reaction space in the main movement direction of the low kinetic energy.

Derartige Anordnungen sind bekannt und zumindest im Laborbetrieb für zwei unterschiedliche Anwendungsfälle in Verwendung:Such arrangements are known and are used at least in laboratory operation for two different applications:

Einerseits können die Eingangsstufen sogenannter Driftröhren-Anordnungen (z.B. SIDT-Quasistatic Selected-lon Drift Tubes) auf diese Weise ausgebildet sein, wobei die aus einer austauschbaren lonenquelle austretenden Primär-Ionen in eine Oktopol-Speicherzone eintreten, wo sie beispielsweise mit einem neutralen Gas bzw. Gasgemisch unter Produktion neuer Ionen in bekannten Anregungszuständen reagieren. Aus der Oktopol-Anordnung bzw. dem davon umgebenen Reaktionsraum treten die Ionen in den Massenspektrometer-Quadrupol ein, wo die zu untersuchende Ionenart auf bekannte und hier nicht weiter interessierende Weise ausgewählt und anschließend über einen venturiartigen Einlaß in die eigentliche Driftkammer eingebracht wird.On the one hand, the input stages of so-called drift tube arrangements (e.g. SIDT-Quasistatic Selected-lon Drift Tubes) can be designed in this way, the primary ions emerging from an exchangeable ion source entering an octopole storage zone, where they can be used, for example, with a neutral gas or React gas mixture with production of new ions in known excitation states. From the octopole arrangement or the reaction space surrounding it, the ions enter the mass spectrometer quadrupole, where the type of ion to be investigated is selected in a known manner which is of no further interest here and then introduced into the actual drift chamber via a venturi-type inlet.

Andererseits kann die eingangs beschriebene Anordnung auch unmittelbar als Massenspektrometer-Analysator Verwendung finden, wobei in diesem Falle das Gasgemisch im Reaktionsraum dadurch untersucht wird, daß mit den Primär-Ionen bestimmte Produkt-Ionen produziert werden, die nach Selektierung im Massenspektrometer-Quadrupol unmittelbar einem lonendetektor zugeführt werden können, was in bekannter Weise eine massenspektrometrische Analyse erlaubt.On the other hand, the arrangement described in the introduction can also be used directly as a mass spectrometer analyzer, in which case the gas mixture in the reaction space is examined by producing certain product ions with the primary ions which, after being selected in the mass spectrometer quadrupole, are immediately used as an ion detector can be supplied, which allows a mass spectrometric analysis in a known manner.

Die Oktopol-Anordnung dient in beiden Fällen zur Festhaltung bzw. Führung der lonen, welche bei niedrigen Bewegungsenergien (darunter werden im allgemeinen Bewegungsenergien kleiner als 100 eV verstanden) aufgrund ihres eigenen Raumladungsdruckes (Coulomb-Abstoßung zwischen den Ladungen) an sich eine hohe Divergenz in ihrer Bewegung aufweisen. Das Erfordernis niedriger kinetischer Bewegungsenergien ist wiederum darauf begründet, daß selektive, fragmentfreie Ionisation - also die Erzeugung einer bestimmten Sorte Produkt-Ionen in einem bestimmten Gas mit einem bestimmten Primär-Ionenstrahl bei möglichst großem Wirkungsgrad - eben nur kleine Bewegungsenergien im Schwerpunktsystem lon/Molekül erlaubt. Der mit niedriger Bewegungsenergie in die Oktopol-Anordnung einlaufende Primär-lonenstrahl wird also durch ein Hochfrequenz-8-Pol-Feld senkrecht zur Bewegungsrichtung der Primär-Ionen im Reaktionsraum gehalten, wobei für das angelegte Hochfrequenzfeld im wesentlichen zwei Bedingungen gelten müssen:

Figure imgb0001
Mit:

  • rRadius der Oktopol-Anordnung
  • vrGeschwindigkeit der Ionen in r-Richtung
  • mFrequenz des HF-Feldes
  • eElementarladung
  • VoAmplitude des HF-Feldes
  • mMasse der Ionen
The octopole arrangement serves in both cases to hold or guide the ions, which at low kinetic energies (which are generally understood to mean kinetic energies less than 100 eV) have a high divergence due to their own space charge pressure (Coulomb repulsion between the charges) of their movement. The requirement for low kinetic kinetic energies is in turn based on the fact that selective, fragment-free ionization - i.e. the generation of a certain type of product ions in a certain gas with a certain primary ion beam with the greatest possible efficiency - only allows small kinetic energies in the ion / molecule center of gravity . The primary ion beam entering the octopole arrangement with low kinetic energy is thus held by a high-frequency 8-pole field perpendicular to the direction of movement of the primary ions in the reaction space, whereby essentially two conditions must apply to the applied high-frequency field:
Figure imgb0001
 With:
  • rRadius of the octopole arrangement
  • vr Speed of the ions in the r direction
  • mfrequency of the HF field
  • Elementary charge
  • VoAmplitude of the HF field
  • m mass of ions

Damit bewegen sich geladene Teilchen in einem zeitunabhängigen effektiven Potential, das im Zentrum - also längs der Achse - Null ist und gegen die einzelnen Elektrodenstäbe hin wie eine Parabelfunktion höherer Ordnung gegen unendlich ansteigt. Dieses Potential wirkt dem Raumladungsdruck der Ionen entgegen und hält damit den lonenstrahl in einem Querschnitt, der durch die Dimension des Innenraumes der Oktopol-Anordnung vorgegeben ist.Thus charged particles move in a time-independent effective potential, which is zero in the center - i.e. along the axis - and rises towards the individual electrode rods like a parabolic function of a higher order against infinity. This potential counteracts the space charge pressure of the ions and thus holds the ion beam in a cross section which is predetermined by the dimension of the interior of the octopole arrangement.

Als großes Problem hat sich im Zusammenhang mit den bekannten Anordnungen der eingangs genannten Art die Tatsache herausgestellt, daß die nach einer Reaktion der Primär-Ionen mit den neutralen Molekülen des Gasgemisches verbleibenden bzw. resultierenden Produkt-Ionen in der Regel keinerlei Information über die notwendige Flugrichtung zum Massenspektrometer-Quadrupol haben, da beim lonenstoß abhängig von der relativen Masse der beteiligten Teilchen ein Teil des Betrages des Impulses vom Ion auf das neutrale Molekül übertragen wird, nicht aber die Richtung des Impulses. Demgemäß bewegen sich die Produkt-Ionen in Zufallsrichtungen, d.h., die Richtungsverteilung entspricht der translatorischen Boltzmann-Verteilung.A major problem in connection with the known arrangements of the type mentioned at the outset was the fact that the product ions remaining or resulting after a reaction of the primary ions with the neutral molecules of the gas mixture generally do not provide any information about the necessary direction of flight to the mass spectrometer quadrupole, because during the ion impact, depending on the relative mass of the particles involved, part of the amount of the momentum is transferred from the ion to the neutral molecule, but not the direction of the momentum. Accordingly, the product ions move in random directions, i.e. the directional distribution corresponds to the translational Boltzmann distribution.

Um nun die Ausbeute an zum Massenpektrometer-Quadrupol gelangenden Produkt-Ionen, die unter Zugrundelegung ausschließlich von Diffusionsvorgängen zum statistischen Ausgleich von Konzentrationsunterschieden natürlich sehr gering ist und vor allen Dingen Messungen von Produkt-Ionen aus bei dynamischen bzw. hochdynamischen Vorgängen entstehenden und durch den Reaktionsraum bewegten Gasgemischen nicht bzw. nur mit zumeist untragbar großen Verzögerungen erlaubt, zu erhöhen, könnte an sich zwar eine gegenüber der Oktopol-Anordnung negatives Potential aufweisende Extraktorlinse nach dem Reaktionsraum angeordnet werden, um die Ionen aus dem Reaktionsraum in den Massenspektrometer-Quadrupol zu fokussieren. Denkbar wäre unter Umständen auch, den Quadrupol selbst auf ein gegenüber der Oktopol-Anordnung negatives Potential zu legen. Beide Maßnahmen sind aber nicht zielführend, weil für den nötigen elektrischen Felddurchgriff in den Reaktionsraum bzw. in die Oktopol-Anordnung sehr hohe Spannungen an diese Extraktorlinse bzw. den Quadrupol gelegt werden müßten. Diese hohen Spannungen von größenordnungsmäßig über 100 V würden aber wiederum in äußerst nachteiliger Weise die Ionen auf so hohe kinetische Energien beschleunigen, daß die Funktion des nachgeschalteten Massenspektrometer-Quadrupols schwer beeinträchtigt, d.h. sein Auflösungsvermögen stark vermindert würde.Now about the yield of product ions reaching the mass spectrometer quadrupole, which is of course very low on the basis of only diffusion processes for the statistical compensation of concentration differences, and above all measurements of product ions from dynamic or highly dynamic processes and through the reaction space moving gas mixtures could not be increased, or only allowed with mostly intolerably large delays as such, an extractor lens with a potential that is negative compared to the octopole arrangement is arranged after the reaction space in order to focus the ions from the reaction space into the mass spectrometer quadrupole. Under certain circumstances it would also be conceivable to place the quadrupole itself at a potential which is negative compared to the octopole arrangement. However, both measures are not expedient because very high voltages would have to be applied to this extractor lens or the quadrupole for the necessary electrical field penetration into the reaction space or into the octopole arrangement. These high voltages of the order of magnitude over 100 V would, however, in an extremely disadvantageous manner accelerate the ions to such high kinetic energies that the function of the downstream mass spectrometer quadrupole would be seriously impaired, ie its resolution would be greatly reduced.

Aufgabe der vorliegenden Erfindung ist es, eine Anordnung der eingangs genannten Art so zu verbessern, daß die genannten Nachteile der bekannten Anordnungen vermieden werden und daß insbesonders auf einfache Weise die Zuführungsrate und Zuführungsgeschwindigkeit von im Reaktionsraum gebildeten Produkt-Ionen zum Massenspektrometer-Quadrupol erhöht werden.The object of the present invention is to improve an arrangement of the type mentioned at the outset in such a way that the disadvantages of the known arrangements are avoided and in particular that the supply rate and supply speed of product ions formed in the reaction space to the mass spectrometer quadrupole are increased in a simple manner.

Dies wird gemäß der vorliegenden Erfindung dadurch erreicht, daß die Oktopol-Anordnung in Längsrichtung in einzelne, voneinander elektrisch isolierte Bereiche aufgeteilt ist, welche - von der lonenquelle zum Massenspektrometer-Quadrupol gesehen - auf jeweils gegenüber dem vorherigen Bereich ansteigendem, negativem Gleichspannungspotential liegen. Damit wird am jeweils n-ten Oktopol-Bereich ein Gleichspannungspotential erzeugt, das negativ gegenüber dem (n - 1)-ten Bereich aber posiiv gegenüber dem (n + 1)-ten Bereich ist. Im Zentrum bzw. in der Achse der Oktopol-Anordnung wird damit ein homogenes elektrisches Feld in Achsrichtung zum Massenspektrometer-Quadrupol erzeugt, welches den Produkt-Ionen als treibende Kraft dient. Da die Zufalls-Bewegungsenergie der Produkt-Ionen im allgemeinen nicht größer als 1 eV ist, genügen bereits sehr geringe Feldstärken, wodurch Störungen des Massenspektrometer-Quadrupols durch hohe kinetische Energien der ankommenden Produkt-Ionen sicher vermieden werden.This is achieved in accordance with the present invention in that the octopole arrangement is divided in the longitudinal direction into individual regions which are electrically insulated from one another and which, viewed from the ion source to the mass spectrometer quadrupole, are each at a negative DC voltage potential which rises in relation to the previous region. In this way, a DC voltage potential is generated at the nth octopole range, which is negative compared to the (n - 1) th range but positive compared to the (n + 1) th range. In the center or in the axis of the octopole arrangement, a homogeneous electric field is generated in the axial direction to the mass spectrometer quadrupole, which serves as the driving force for the product ions. Since the random kinetic energy of the product ions is generally not greater than 1 eV, very low field strengths are sufficient, which reliably prevents disturbances of the mass spectrometer quadrupole due to high kinetic energies of the incoming product ions.

Die am Oktopol insgesamt wirksame Gleichspannung liegt nach einer bevorzugten Ausbildung der Erfindung im Bereich 5 bis 30 V.According to a preferred embodiment of the invention, the total DC voltage effective at the octopole is in the range 5 to 30 V.

Nach einer weiteren Ausgestaltung der Erfindung ist vorgesehen, daß die Gleichspannungs-Feldstärke am Oktopol gleichmäßig 0,5 bis 3 V/cm beträgt, vorzugsweise 1 V/cm.According to a further embodiment of the invention it is provided that the direct voltage field strength at the octopole is uniformly 0.5 to 3 V / cm, preferably 1 V / cm.

Da die Zufalls-Bewegungsenergie der Produkt-Ionen im allgemeinen nicht größer als 1 eV ist, genügt an sich eine Feldstärke von 1 V/cm. Dies ergibt z.B. bei einer 10 cm langen Oktopol-Anordnung Produkt-Ionen mit Energien von maximal 10 eV, was für den Massenspektrometer-Quadrupol keine Störung bewirkt, da dessen Energieakzeptanz üblicherweise bei etwa 40 eV liegt.Since the random kinetic energy of the product ions is generally not greater than 1 eV, a field strength of 1 V / cm is in itself sufficient. This gives e.g. with a 10 cm long octopole arrangement, product ions with energies of at most 10 eV, which does not cause any disturbance for the mass spectrometer quadrupole, since its energy acceptance is usually around 40 eV.

Gemäß einer bevorzugten weiteren Ausgestaltung der Erfindung liegen die einzelnen Oktopol-Bereiche über eine Widerstandskette an einer gemeinsamen Gleichspannungsversorgung, was einen einfachen Aufbau der Anordnung ermöglicht und einen kontrollierten Feldverlauf über die gesamte Länge der Oktopol-Anordnung ermöglicht.According to a preferred further embodiment of the invention, the individual octopole regions are connected to a common DC voltage supply via a resistor chain, which enables a simple structure of the arrangement and enables a controlled field profile over the entire length of the octopole arrangement.

Die Erfindung wird im folgenden noch anhand der Zeichnung näher erläutert.

  • Fig. 1 zeigt in schematischer,geschnittener Darstellung eine Massenspektrometer-Anordnung nach der vorliegenden Erfindung,
  • Fig. 2 einen schematischen Schnitt durch einen einzelnen Oktopol-Bereich entlang der Linie 11-11 in Fig. 1 in anderem Maßstab,
  • Fig. 3 ein Potential V/Radius r-Diagramm der Anordnung nach Fig. 2,
  • Fig. 4 eine in drei einzelne Bereiche aufgeteilte Oktopol-Anordnung zur Verwendung in einer Massenspektrometer-Anordnung nach der Erfindung und
  • Fig. 5 ein Potential/Radius/Längserstreckung-Diagramm einer Oktopol-Anordnung gemäß Fig. 4.
The invention is explained in more detail below with reference to the drawing.
  • 1 shows a schematic, sectional illustration of a mass spectrometer arrangement according to the present invention,
  • 2 shows a schematic section through a single octopole region along the line 11-11 in FIG. 1 on a different scale,
  • 3 shows a potential V / radius r diagram of the arrangement according to FIG. 2,
  • Fig. 4 shows an octopole arrangement divided into three individual areas for use in a mass spectrometer arrangement according to the invention and
  • 5 shows a potential / radius / longitudinal extension diagram of an octopole arrangement according to FIG. 4.

Die Massenspektrometer-Anordnung nach Fig. 1 weist eine Ionenquelle 1 von beliebiger, hier nicht näher interessierender Bauart, einen an die lonenquelle 1 anschließenden Reaktionsraum 2, sowie einen in Hauptbewegungsrichtung z der von der lonenquelle 1 gelieferten Primär-Ionen an den Reaktionsraum 2 anschließenden Massenspektrometer-Quadrupol 3 auf. Der Reaktionsraum 2, dem über einen Anschluß 4 ein Gas bzw. Gasgemisch zugeführt werden kann, ist von einer Oktopol-Anordnung 5 mit einem senkrecht zur Hauptbewegungsrichtung z der Primär-Ionen wirkenden Hochfrequenz-8-Pol-Feld umgeben, das zur Sammlung, Halterung bzw. Führung der eine sehr niedrige Bewegungsenergie von typischerweise unterhalb 100 eV aufweisenden Primär-Ionen dient. Die im Massenspektrometer-Quadrupol 3 auf hier ebenfalls nicht weiter interessante, bekannte Art selektierten Produkt-Ionen gelangen an einen lonensensor 6, der ebenfalls von bekannter bzw. üblicher Bauart sein kann und dessen Funktion und Wirkungsweise hier nicht näher interessiert.The mass spectrometer arrangement according to FIG. 1 has an ion source 1 of any design, not of interest here, a reaction space 2 connecting to the ion source 1, and a mass spectrometer connecting the primary ions supplied by the ion source 1 to the reaction space 2 in the main direction of movement z Quadrupole 3 on. The reaction chamber 2, to which a gas or gas mixture can be supplied via a connection 4, is surrounded by an octopole arrangement 5 with a high-frequency 8-pole field acting perpendicular to the main direction of movement z of the primary ions, which is used for collection and mounting or guidance of the primary ions, which have a very low kinetic energy of typically below 100 eV. The product ions selected in the mass spectrometer quadrupole 3 in a known manner, which is likewise of no further interest here, arrive at an ion sensor 6, which can also be of a known or customary type and whose function and mode of action are not of interest here.

Der Einfachheit der Darstellung wegen sind verschiedene, teilsweise für die Funktion der Anordnung im üblichen Betrieb unerlässliche Zusatzeinrichtungen, wie Blenden bzw. Linsen für den Ionenstrahl oder Vakuumpumpen und Abdichtungen und dergleichen nicht gezeichnet, da sie im Zusammenhang mit der vorliegenden Erfindung von untergeordneter Bedeutung sind.For the sake of simplicity of illustration, various additional devices, such as diaphragms or lenses for the ion beam or vacuum pumps and seals and the like, some of which are indispensable for the function of the arrangement in normal operation, are not shown, since they are of secondary importance in connection with the present invention.

Die Oktopol-Anordnung 5 ist in Längsrichtung - also in Hauptbewegungsrichtung z der aus der lonenquelle 1 in einem Strahl austretenden Primär-Ionen - in drei einzelne, voneinander elektrisch isolierte Bereiche 7, 8, 9 aufgeteilt, welche - von der lonenquelle 1 zum Massenspektrometer-Quadrupol 3 gesehen - auf jeweils gegenüber dem vorherigen Bereich ansteigendem negativen Gleichspannungspotential liegen.The octopole arrangement 5 is in the longitudinal direction - that is, in the main direction of movement z of the primary ions emerging from the ion source 1 in a beam - into three individual Be electrically isolated from each other rich 7, 8, 9 divided, which - as seen from the ion source 1 to the mass spectrometer quadrupole 3 - are each at a negative DC voltage potential that increases in relation to the previous region.

In Fig. 2 sind die einzelnen acht Stäbe des Bereiches 7 der Oktopol-Anordnung 5 im Schnitt angedeutet. Je vier davon sind gemeinsam kontaktiert, wobei auf hier nicht dargestellte Weise ein hochfrequentes Wechselfeld (Potential V= ) angelegt wird, welches im Innenraum zwischen den acht Stäben der Oktopol-Anordnung ein Hochfrequenzführungsfeld Veff bewirkt, welches im Diagramm nach Fig. 3 angedeutet ist. Mit ro und -ro sind in Fig. 3 die Ränder bzw. Oberflächen von zwei gegenüberliegenden Stäben markiert - es ist zu erkennen, daß das effektive Potential im Zentrum der Anordnung (r = 0) Null ist und gegen die Oktopol-Elektrodenstäbe hin wie eine Parabelfunktion höherer Ordnung gegen unendlich ansteigt. Dieses Potential Veff wirkt dem Raumladungsdruck (Coulomb-Abstoßung zwischen den Ladungen) der nur sehr niedrige Bewegungsenergie aufweisenden Ionen entgegen und hält damit diese in einem Querschnitt, der durch die Dimension der Oktopol-Anordnung 5 vorgegeben ist.The individual eight rods of the area 7 of the octopole arrangement 5 are indicated in section in FIG. 2. Four of them are contacted together, whereby a high-frequency alternating field (potential V =) is applied in a manner not shown here, which causes a high-frequency guide field V eff in the interior between the eight rods of the octopole arrangement, which is indicated in the diagram in FIG. 3 . The edges or surfaces of two opposite rods are marked with ro and -ro in FIG. 3 - it can be seen that the effective potential in the center of the arrangement (r = 0) is zero and towards the octopole electrode rods like one Parabolic function of higher order increases towards infinity. This potential V eff counteracts the space charge pressure (Coulomb repulsion between the charges) of the ions which have only very low kinetic energy and thus keeps them in a cross section which is predetermined by the dimension of the octopole arrangement 5.

Die auch aus Fig. 4 ersichtliche Aufteilung der gesamten Oktopol-Anordnung 5 in drei einzelne, ein dem Hochfrequenz-Führungsfeld überlagertes Gleichspannungsfeld erzeugende Bereiche 7, 8, 9 dient dazu, die im Reaktionsraum 2 von den Primär-Ionen in Stößen mit den Gasteilchen des über den Anschluß 4 zugeführten Gases bzw. Gasgemisches erzeugten Produkt-Ionen möglichst rasch und vollständig aus dem Reaktionsraum 2 zu bringen und dem Massenspektrometer-Quadrupol 3 (Fig. 1) zur Selektion bzw. zum anschließenden Nachweis zuzuführen. In Fig. 4 sind auch schematisch die Potentialanschlüsse an den Bereichen 7, 8, 9 der Oktopol-Anordnung 5 dargestellt; das Hochfrequenz- Führungsfeld bzw. das Potential V= ist für alle drei Bereiche gleich; das überlagerte negative Gleichspannungspotential steigt von U1 über U2 bis U3 an, wobei die entsprechende Feldstärke beispielsweise 1 V/cm beträgt. Das Gesamtpotential VTot über die Länge der Oktopol-Anordnung ist aus Fig. 5 zu ersehen. Das Potential des HF-Feldes ist ein parabelförmiger Trog, der durch das - hier über die ganze Länge gleichmäßige - Potential des überlagerten E-Feldes am Eingang der Oktopol-Anordnung quasi angehoben wird. Aus der Darstellung der Fig. 5 ist auch bildlich leicht zu erkennen, wie die Ionen einerseits in dem im Inneren der Oktopol-Anordnung definierten Reaktionsraum gehalten und andererseits in Richtung zum Massenspektrometer-Quadrupol rasch aber mit geringer Bewegungsenergie abgeführt werden.The division of the entire octopole arrangement 5, which can also be seen in FIG. 4, into three individual regions 7, 8, 9 which generate a direct current field which is superimposed on the high-frequency guide field, serves to separate the primary ions from the primary ions in collisions with the gas particles to bring product ions generated via the connection 4 supplied gas or gas mixture as quickly and completely as possible out of the reaction space 2 and to feed them to the mass spectrometer quadrupole 3 (FIG. 1) for selection or subsequent detection. 4 also schematically shows the potential connections at the areas 7, 8, 9 of the octopole arrangement 5; the high frequency guide field or the potential V = is the same for all three areas; the superimposed negative DC voltage potential increases from U 1 to U 2 to U 3 , the corresponding field strength being, for example, 1 V / cm. The total potential V Tot over the length of the octopole arrangement can be seen from FIG. 5. The potential of the HF field is a parabolic trough, which is quasi raised by the - here uniform over the entire length - potential of the superimposed E field at the entrance of the octopole arrangement. From the illustration in FIG. 5 it is also easy to see figuratively how the ions on the one hand are held in the reaction space defined in the interior of the octopole arrangement and on the other hand are rapidly dissipated towards the mass spectrometer quadrupole but with little kinetic energy.

Abweichend von der dargestellten Aufteilung der Oktopol-Anordnung 5 in drei einzelne Bereiche könnte natürlich auch eine Aufteilung in zwei oder aber in an sich beliebig viele Bereiche erfolgen, die - wie erwähnt - auf unterschiedlichem Gleichspannungspotential liegen.Deviating from the shown division of the octopole arrangement 5 into three individual regions, a division into two or, as such, any number of regions could naturally also take place which, as mentioned, are at different DC potentials.

Claims (5)

1. Mass spectrometer arrangement with an ion source, a reaction chamber following it and receiving a gas or gas mixture and surrounded by an octopole arrangement with a high frequency 8-pole field acting perpendicular to the principal direction of travel of the primary ions produced by the ion source, and a mass spectrometer quadrupole following on the reaction chamber in the principal direction of travel of the primary ions having a low kinetic energy, characterised in that the octopole arrangement (5) is split up in the longitudinal direction into individual mutually electrically insulated regions (7, 8, 9) - looked at from the ion source (1) to the miss spectrometer quadrupole (3) - to which are applied negative d.c. potentials (U1, U2, Ua) increasing respectively in relation to the preceding region.
2. Arrangement according to claim 1 characterised in that the d.c. voltage acting in total on the octopole (5) lies in the region of 5-30 V.
3. Arrangement according to claim 1 or 2 characterised in that the d.c. field strength at the octopole amounts to uniformly 0.5 to 3 V/cm.
4. Arrangement according to claim 3 characterised in that the d.c. field strength at the octopole is uniformly 1 V/cm.
5. Arrangement according to one of claims 1 to 4 characterised in that the individual octopole regions (7, 8, 9) are connected through a resistor chain to a common d.c. voltage supply.
EP19870890179 1987-05-11 1987-07-20 Mass spectrometer Expired - Lifetime EP0290712B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT1177/87 1987-05-11
AT0117787A AT388629B (en) 1987-05-11 1987-05-11 MASS SPECTROMETER ARRANGEMENT

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EP0290712A1 EP0290712A1 (en) 1988-11-17
EP0290712B1 true EP0290712B1 (en) 1990-11-07

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JPH02304854A (en) * 1989-05-19 1990-12-18 Jeol Ltd Simultaneous detecting type mass spectrometer
EP0843887A1 (en) * 1995-08-11 1998-05-27 Mds Health Group Limited Spectrometer with axial field
DE19628093B4 (en) * 1996-07-12 2006-09-21 Deutsches Zentrum für Luft- und Raumfahrt e.V. Method and device for detecting sample molecules
EP1217643B1 (en) 2000-12-15 2008-09-10 V & F Analyse- und Messtechnik G.m.b.H. Method and apparatus for the determination of the state of organisms and natural products and for the analysis of gaseous mixtures having main components and secondary components
US6800846B2 (en) 2002-05-30 2004-10-05 Micromass Uk Limited Mass spectrometer
US6884995B2 (en) 2002-07-03 2005-04-26 Micromass Uk Limited Mass spectrometer
US6897438B2 (en) 2002-08-05 2005-05-24 University Of British Columbia Geometry for generating a two-dimensional substantially quadrupole field
US7045797B2 (en) 2002-08-05 2006-05-16 The University Of British Columbia Axial ejection with improved geometry for generating a two-dimensional substantially quadrupole field
DE10236345A1 (en) * 2002-08-08 2004-02-19 Bruker Daltonik Gmbh Ion-analyzing device for ejecting stored ions on-axis selected by bulk from linear ion traps has apertures, an ion detector and an ion trap made up of high-frequency-wired pole rods
EP1668665A4 (en) 2003-09-25 2008-03-19 Mds Inc Dba Mds Sciex Method and apparatus for providing two-dimensional substantially quadrupole fields having selected hexapole components
GB2427067B (en) * 2005-03-29 2010-02-24 Thermo Finnigan Llc Improvements relating to ion trapping
EP3418714A1 (en) 2017-06-19 2018-12-26 V&F Analyse- und Messtechnik GmbH Device and method for partial transfer of a liquid sample comprising multiple components, and method for the online determination and analysis of these components

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JPS59123155A (en) * 1982-12-28 1984-07-16 Jeol Ltd Tetrode mass spectrograph

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ATA117787A (en) 1988-12-15
EP0290712A1 (en) 1988-11-17
AT388629B (en) 1989-08-10
DE3766102D1 (en) 1990-12-13

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