US3621240A - Apparatus and methods for detecting and identifying trace gases - Google Patents

Apparatus and methods for detecting and identifying trace gases Download PDF

Info

Publication number
US3621240A
US3621240A US828402A US3621240DA US3621240A US 3621240 A US3621240 A US 3621240A US 828402 A US828402 A US 828402A US 3621240D A US3621240D A US 3621240DA US 3621240 A US3621240 A US 3621240A
Authority
US
United States
Prior art keywords
chamber
accordance
ions
product ions
ion
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 - Lifetime
Application number
US828402A
Inventor
Martin J Cohen
David I Carroll
Roger F Wernlund
Wallace D Kilpatrick
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.)
PCP Inc A CORP OF FLORIDA
Original Assignee
FRANKLIN GRO CORP
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 FRANKLIN GRO CORP filed Critical FRANKLIN GRO CORP
Application granted granted Critical
Publication of US3621240A publication Critical patent/US3621240A/en
Assigned to GIBSON HENRY C,JR. TRUSTEE FOR THE STOCKHOLDERS reassignment GIBSON HENRY C,JR. TRUSTEE FOR THE STOCKHOLDERS ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: FRANKLIN GNO CORPORATION A FL CORP.
Assigned to PCP, INC., A CORP. OF FLORIDA reassignment PCP, INC., A CORP. OF FLORIDA ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: GIBSON HENRY C, JR. TRUSTEE FOR THE STOCKHOLDERS OF FRANKLIN GNO CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00Particle spectrometers or separator tubes
    • H01J49/004Combinations of spectrometers, tandem spectrometers, e.g. MS/MS, MSn
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00Particle spectrometers or separator tubes
    • H01J49/26Mass spectrometers or separator tubes
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • G01N30/02Column chromatography
    • G01N30/62Detectors specially adapted therefor
    • G01N30/72Mass spectrometers
    • G01N30/7206Mass spectrometers interfaced to gas chromatograph

Definitions

  • Prior techniques for the analysis of trace gases are deficient in one or more of the following respects: (1) the necessity of obtaining discrete samples of the gas to be analyzed, (2) fragmentation of the parent material, (3) the requirement of long measurement time.
  • the system of that application involves the formation of primary or reactant ions from a reactant gas and the reaction of the primary ions with molecules of trace substances to form secondary or product ions, which may be concentrated, separated, detected, and measured by virtue of the velocity or mobility of the ions in an electric field.
  • a significant advantage of the system is that measurements are preferably performed at or about atmospheric pressure.
  • the resolution of the apparatus described in the copending application is, however, not as great as that of gas chromatography, for example, and therefore, some ambiguity may exist where it is desired to identify particular trace gas constituents of the sample.
  • a further object of the invention is to provide apparatus and methods of the foregoing type which do not require the collection of discrete samples, which avoid modification of parent materials, and which operate rapidly and at high sensitivity.
  • the present invention is concerned with a measurement technique in which ions of trace gases are formed as the product of ion-molecule reactions in a drift cell operated at atmospheric pressure.
  • the product ions are separated in accordance with their drift velocity and are passed in a molecular beam to a mass analyzer, operated at high vacuum, via a transition region at which the ions are focused and the neutral molecules of the molecular beam are separated from the ions. Ions selected by the mass analyzer are counted or otherwise detected.
  • FIG, I is a diagrammatic perspective view of one form of the invention.
  • FIG. 2 is a diagrammatic longitudinal sectional view of a second form of the invention.
  • apparatus in accordance with the invention comprises a Plasma Chromatograph I0, a mass analyzer I2 connected to the Plasma Chromatograph via a transition section I4, and an ion detector I6.
  • the Plasma Chromatograph which is shown quite diagrammatically in FIG. I, is illustrated in greater detail in FIG. 2.
  • Such apparatus is disclosed in the aforesaid copending application, and, in an improved form, in the copending application of David I. Carroll, Martin J. Cohen, and Roger F. Wernlund, Ser. No. 780,851, filed Dec. 3, 1968, and entitled Apparatus and Methods for Separating, Detecting, and Measuring Trace Gases with Enhanced Resolution".
  • the Plasma Chromatography technique involves the production of primary ions by subjecting the molecules of a host gas, such as air, to ionizing radiation, for example.
  • the primary ions are subjected to an electric drift field, causing them to migrate in a predetermined. direction through a reaction space into which the sample or trace gas is introduced.
  • the resultant collisions between the primary ions and the trace gas molecules produce secondary ions of the trace gas in much greater numbers than can be produced by mere electron attachment, for example, to the trace gas molecules.
  • the secondary or product ions are also subjected to the drift field.
  • the drift cell of the Plasma Chromatograph is operated (preferably at atmospheric pressure) so as to maintain the mean free path of the product ions much smaller than the dimensions of the cell, the ions reach statistical terminal velocity in the drift field dependent upon their mass and may be sorted in accordance with their velocity or mobility.
  • Specific systems of the copending applications employ a pair of successively arranged ion shutter grids or gates for segregating the ion species in accordance with their drift time.
  • the opening of the first gate is timed to pass a group of ions, which may comprise unreacted primary ions as well as secondary or product ions, and the opening of the second gate is timed to pass a portion of the group to an ion detection means.
  • a drift cell which comprises part of an envelope II, of metal for example, having a sample inlet I3 and an outlet 26.
  • the envelope contains a series of spaced electrodes. which may have parallel plane geometry, for example, and which may include a pair of principal electrodes C and A and a pair of shutter grids or ion gates GI and G2. If the apparatus is to be employed to detect negative ions, electrode C will be a cathode and electrode A will be an anode, while if positive ions are to be detected, the polarities will be reversed.
  • the electrodes may be spaced-apart distances of the order of a few centimeters or less (for example, cathode to anode spacing of about 10 centimeters) and may have suitable lead wires passing through the envelope by means of insulators (not shown). Electrode C or the region of the envelope near this electrode is provided with an ionizing means, such as a photo emission source, a radioactive source, a multiple point or wire array (corona) source, or an RF ionization source.
  • the ionizer I is a radioactive source, such as tritium foil. The foil may be placed at the end of the inlet tube I3 which exits through an opening in electrode C.
  • the grids GI and G2 may be of the parallel wire type. Alternate wires of each of the grids are connected together to form two separate groups, so that each shutter grid comprises two interdigitated subgrids of parallel wires. Adjacent elements of each grid are normally maintained at equal and opposite potentials relative to a grid average potential, and under these conditions, the shutter or gate is closed to the passage of electrically charged particles.
  • the potential sources which provide the equal and opposite potentials just referred to may be considered to be part of grid drive circuits contained within the block I7. The components of this block are effective to drive the adjacent elements of each shutter grid to the same potential, the' grid average potential, at predetermined instants.
  • the grids per se and the circuits for driving the same are known in the art and need no further elucidation.
  • Electrode A would, in the Plasma Chromatograph of the type disclosed in the aforesaid copending applications, serve as a collector plate connected to an output divide.
  • this electrode also serves as an apertured partition to permit ions to exit from the drift chamber 18 in the envelope 11, the electrode being provided with a central aperture 19 for the passage of a molecular beam.
  • An electric drift field is provided between electrodes C and A.
  • the source of drift field is a battery 20 connected across a resistor chain 22, taps of which provide static potentials for the electrodes contained within chamber 18.
  • electrode A is connected to ground, as is the positive side of the battery 20, and the negative side of battery 20 is connected to electrode C.
  • the grid average potential for grid G1 is provided by connecting each subgrid through a series resistor (not shown) to the same point on the resistor chain 22. The grid drive potentials are applied to the junctions of the series resistors and the subgrids, respectively.
  • Grid G2 is similarly supplied.
  • a series of guard rings 24 is provided along the perimeter of the envelope to maintain the uniformity of the electric field between the electrodes.
  • the guard rings are also connected to successive points on the resistor chain.
  • Suitable supports and spacers such as quartz rods and tubes, may be employed to support the various electrodes within the envelope.
  • the apparatus of the invention also preferably includes an additional inlet 15 through which a nonreactive buffering as, such as nitrogen, may be introduced into the envelope as described in copending application Ser. No. 780,851.
  • air carrying a suitable ionizable gaseous trace substance such as methane or SF flows into the chamber 18 by means of the inlet 13 and is exhausted through the outlet 26.
  • Any suitable source of flow pressure such as a fan, may be employed to move the carrier gas containing the trace substances.
  • ions of the carrier or host gas or one or more of the main constituents thereof, such as oxygen are formed under the influence of the radioactive source at this region.
  • the primary ions may be negative oxygen ions, for example, formed by direct attachment of electrons to the oxygen molecules.
  • the ions drift toward electrode A under the influence of the drift field.
  • the primary ions formed at electrode C react with molecules of the trace vapors to convert these molecules to product ions. Further ionmolecule reactions are quenched by the nonreactive gas supplied by inlet 15.
  • shutter grid G1 is periodically opened to sample the products of the reaction and any other ion species present.
  • the opening of grid Gl at a predetermined time and for a predetermined duration constitutes a timed reference pulse during which a group of ions is passed into the ion mobility analysis region between GI and G2.
  • a predetermined duration for example, millisecond
  • the ions drift from G] to G2 they become grouped or classified in accordance with the velocity (a function of ion mass) in the drift field. Because the mean free path of the ions in chamber 18 is much less than the chamber dimensions (by virtue of the relatively high-atmospheric pressure), statistical terminal velocity is reached.
  • grid G2 is opened for a predetermined duration to select a portion of the ion mobility spectrum within the region G1 to G2 for passage toward electrode A.
  • Those ions which impinge upon electrode A produce an output current which may be measured by an electrometer (not shown).
  • the output current varies in time according to the characteristic drift time of each species as the various species traverse the drift cell.
  • the ions are nonnally detected as pulses and thereby permit a time display for the ion species present. By scanning the time of opening of grid G2 relative to G1, the entire drift spectrum may be displayed.
  • the Plasma Chromatograph 10 is assumed to be constructed and to operate like that of FIG. 2, rings 28 being a diagrammatic representation of the grids G1 and G2 and the guard rings 24 of FIG. 2.
  • the product ions passed toward electrode A are sampled by the aperture 19, a
  • the transition section 14 of the envelope 11 comprises a chamber 30 connected by a pipe 32 to a vacuum system for pumping out the chamber (to a vacuum of say 0.5 to 2 Torr). There is thus a supersonic expansion of the jetstream at the aperture 19 from the high-pressure (760 Torr) conditions in chamber 18 to the vacuum conditions in chamber 30.
  • the transition section transposes ions from an ambient pressure region to a substantially lower pressure region without substantial modification either of the quantity of the ions transferred or the species of the ions transferred.
  • the centrally apertured electrodes 34 (aperture diameter 0.005 to 0.015 inch, for example) in the transition section are diagrammatic representations of conventional ion-focusing electrodes for focusing the product ions into a beam and for preventing dispersion of the ions within the transition region. Neutral molecules in this region are separated from the ion beam by virtue of the vacuum pumping.
  • the series of apertures is radially transparent to gas velocities in the molecular beam and opaque to ion velocities in the molecular beam.
  • Ion Species of the Plasma Chromatograph are preserved at all times, so that mass analysis is not subject to the extensive fragmentation found in conventional ion-source spectrometers. Further, the maximum number of ions present in the ambient atmosphere is extracted and introduced efficiently into the mass analyzer. High trace gas sensitivity is provided by concentration (focusing) of the charged carriers, but the fields are kept low enough to avoid changes in ion species.
  • the beam of ions passes from the transition region 14 to the mass analyzer 12 through an aperture 36 in an electrode A upon the wall of chamber 38, which constitutes a further portion of the envelope 11, an accelerating potential being applied between electrodes A and A.
  • the input potential to the mass analyzer is set for the dual purpose of setting the ion velocity and reducing ion losses (analog to ion focusing).
  • the mass analyzer is of a conventional type.
  • the preferred quadrupole type (readily adapted to both positive and negative ions as well as ion counting), comprising the usual rectangular arrangement of elongated electrodes 40 is shown, although other types, such as time-of-flight, magnetic deflection, or RF separator, may be employed.
  • An accelerating potential is applied between electrodes A' and A" at opposite ends of chamber 38.
  • the product ions are separated in accordance with their mass, and selected ions are passed to the ion detector 16 through an aperture 42 in electrode A" upon the wall of the detector chamber 44, which forms a further section of the envelope 1 1.
  • Both the mass analyzer and detector sections are maintained at high vacuum by connection of the pipes 46 and 48 to a high-vacuum system.
  • the premure in chamber 38 may be 10 Torr or less to reduce ion scattering.
  • the mean free path of ions in chamber 38 is much longer than that in chamber 18 and is preferably substantially longer than the dimensions of the mass analyzer structure, so that the mass analyzer operates under molecular flow conditions. Fast pumping speeds for the neutral gas in the mass analyzer are essential. However, the sampling technique removes such small quantities of gas from chamber 18 that measurements in the Plasma Chromatography drift cell can be accomplished under essentially static conditions.
  • the detector is preferably an ion-counting device capable of registering l to 10,000 counts per second.
  • the detector employs an electron multiplier including a series of dynodes 50 in a conventional arrangement for producing secondary electrons in response to the product ions passed through aperture 42.
  • the output electrode of the detector may be condenser-coupled to a conventional pulse-counting device. Pumpout and vacuum conditioning of the detector is desirable to maintain surface conditions most suitable for high secondary electron yields and thus high sensitivity.
  • the Plasma Chromatograph is capable of detecting trace gases with high sensitivity.
  • the produce ion output of the Plasma Chromatograph may be influenced by varying the ratio of the drift field to the ambient pressure within chamber 18, by controlling the timing of grid G2 relative to grid G1, and by selecting the reactant gases from'which the primary ions are formed.
  • a particular species of product ion may be passed to the detector and identified (by mass number) with great accuracy.
  • the focusing structure provided in the transition section M ensures that the ions are maintained as a beam for application to the mass analyzer, and the pumpout at this region reduces scattering of the beam due to collision with background gases.
  • Ion-focusing structure may also be provided between grid G2 and electrode A to collimate ions for application to the aperture 119.
  • An ion-accelerating potential out of the mass analyzer of about 2,500 volts (between electrode A" and A) is provided to gain enough energy to produce electrons at the first dynode of the detector 16 by secondary emission, for multiplication by further secondary emission in the multiplier structure.
  • the multiplier structure needs an electronaccelerating potential of about 2,000 volts, which is provided between the input and output electrodes thereof.
  • electrode A For positive ions electrode A may be grounded, and electrode C may be 1,000 volts positive relative to ground. Electrode A may be 100 volts negative relative to ground, and electrode A" may be 5,000 volts negative relative to ground.
  • the output electrode of the multiplier may be 2,000 volts positive relative to the input electrode thereof. For negative ions the polarities, except in the multiplier, are reversed. Thus, the multiplier output electrode will be +7,000 volts relative to ground. DC blocking is provided by virtue of the coupling capacitor from the multiplier anode to the output circuit.
  • FIG. 2 illustrates an embodiment of the invention with a modified transition section and a modified detector section. Although shown together for illustrative purposes, the modified sections may be substituted individually for the corresponding sections of FIG. 1.
  • FIG. 2 employs a scintillation detector.
  • a scintillator 52 which may be a conventional plastic, anthracene, or phosphor type, for example, or which may utilize a semiconductor detector element.
  • the scintillator may be biased at 5,000 volts relative to ground, for example, by means of a DC supply represented by the battery 54.
  • the polarity of the battery as shown is for detecting negative ions and would be reversed for detecting positive ions.
  • Scintillations from the detector element 52 are passed by a quartz light pipe 56 to a suitably housed photomultiplier 58 (protected from ambient light).
  • the quartz light pipe provides optical conduction as well as electrical insulation.
  • the scintillator can be operated "hot” and the photomultiplier at normal potentials with the anode substantially at ground.
  • An integrated output may be taken from the output resistor 60 representing the input impedance of electrometer or of a pulse counter.
  • Aperture M may be 10 to 50 times the diameter of aperture 19, for example.
  • Aperture 64 is operated at a repulsive potential relative to aperture 19 of say l 00 volts for negative ions. In a vacuum this electrode would prevent ions from passing through the aperture 64.
  • a high-velocity gas stream mixed with ions issues from the aperture 64.
  • This gas stream collisions, carries the ions through the aperture to the point where the grounded quadrupole structure can attract them.
  • advantage is taken of the viscous drag of the highvelocity (sonic) gas stream to carry the ions across the potential barrier into the region where, at lower pressure, they are focused into the mass analyzer.
  • FIG. 2 also illustrates the utilization of a skimmer 68 for ion focusing and separation of neutral molecules.
  • the skimmer is a conical electrode with a central aperture 70 and is located downstream of electrode 62 by say 1 cm. or less.
  • the diameter of aperture 70 may be of the order ofa mean free path length.
  • the skimmer may be operated at a potential of say -30 volts relative to ground.
  • the skimmer 68, electrode 62 (and the other "hot" electrodes described) are of course isolated from the envelope (if metal) by suitable insulators (not shown). Further electrodes may be placed between the skimmer and the mass analyzer rods to focus ions into the mass analyzer in accordance with conventional techniques.
  • the pressure in transition chamber 30 may be 0.5 to 2 Torr, while the pressure in chamber 38' may be 110" Torr.
  • Chambers 30' and 38 are connected to the high-vacuum system by piper 32 and 46'.
  • the detector operates efficiently at the same pressure as the mass analyzer and need not be placed in a separate chamber.
  • the transition sections of FIGS. l and 2 may be subdivided into successive sections, which may be separately pumped to successively lower pressures, and the divider walls may be constituted by skimmers of the type shown in FIG. 2, for example.
  • the invention permits identification of the parent trace gas ion species by mobility, by virtue of the Plasma Chromatograph, and more selective identification by mass number, by virtue of the mass analyzer.
  • the apparatus as a whole detects the trace gas more sensitively than a mass analyzer alone and identifies species more accurately than a Plasma Chromatograph alone.
  • the Plasma Chromatograph while preferably operated at atmospheric pressure, may be operated above or below atmospheric pressure (assuming that the aforesaid mean free path length conditions are maintained), and the pressures of the mass analyzer and detector are independently chosen.
  • the detector counts ions under gas contamination conditions uncommon to the present state of the art. Output from the detector may be either specific counts or a continuous signal (count rate).
  • the invention may be used to determine ion-molecule reaction rates (particularly where Plasma Chromatography cell pressures are changed) and to perform measurements of elementary particle collision parameters, such as electron attachment cross section and polarizability.
  • the charged particles detected may be charged atoms or clusters, as well as charged molecules, and the terms ion" and ion-molecule reactions" are intended as comprising such particles.
  • a method of detecting trace gas which comprises forming primary ions at a localized region of a first chamber, forming product ions of different mobility at a further region of said first chamber by ion-molecule reactions involving said primary ions and molecules of said trace gas, applying a drift field to said ions and causing them to drift toward a second chamber, maintaining the pressure in said first chamber at a high enough level such that the mean free path of the ions in said first chamber is very small compared to the dimensions of said first chamber and such that said ions reach substantially constant statistical terminal velocity in said first chamber dependent upon their mass and separate in accordance with their mobility, passing saidproduct ions to said second chamber, mainby multiple taining the pressure in said second chamber at a substantially lower level than that in said first chamber such that the mean free path of the product ions in said second chamber is substantially longer than the mean free path in said first chamber, analyzing said product ions in said second chamber in accordance with their mass, and detecting at least some of the analyzed ions.
  • a method in accordance with claim I in which said product ions are transposed from said first chamber to said second chamber as part of a supersonic jetstream molecular beam, and in which the neutral molecules of said beam are separated from product ions of said beam before said product ions are passed to said second chamber.
  • Apparatus for performing ion measurements which comprises an envelope having successive chambers, means within the first of said chambers for forming primary ions at a localized region of said first chamber and for forming difi'erent mobility product ions at a further region of said first chamber by ion-molecule reactions involving said primary ions and molecules of a sample gas, means for subjecting said ions to a drift field and causing them to drift toward a second chamber of said envelope means for maintaining the pressure in said first chamber at a high enough level such that the mean free path of the ions in said first chamber is very much smaller than the chamber dimensions and such that said ions reach substantially constant statistical terminal velocity in said first chamber dependent upon their mass and separate in accordance with their mobility, means for passing product ions from said first chamber to said second chamber, means for maintaining the pressure in said second chamber substantially lower than the pressure in said first chamber such that the mean free path of said product ions in said second chamber is substantially longer than that in said first chamber, means for separating said product ions in said second chamber in accordance
  • said means for passing said product ions from said first chamber to said second chamber comprising an intermediate chamber having means for maintaining the pressure therein at a level between the pressures of said first and secOndchambers.
  • said intermediate chamber having means associated therewith for passing product ions thereto from said first chamber as part of a supersonic jetstream molecular beam and having means for separating neutral molecules of said beam from said product ions.
  • said separating means in said second chamber comprising a mass analyzer.
  • said ion-detecting means comprising an electron multiplier actuated by said product ions.
  • said first chamber having ion-gating means for passing a group of ions from a first region of said first chamber to a second region thereof and having further ion-gating means for passing a portion of the group of ions from the second region to a third region of said first chamber.
  • said first chamber having a pair of electrodes adjacent to opposite ends thereof and having means for applying said drift field between said electrodes.
  • said means for passing said product ions from said first chamber to said second chamber comprising at least a pair of apertured electrodes.
  • said means for passing said product ions from said first chamber to said second chamber comprising an apertured electrode which diverges from said first chamber toward said second chamber.
  • said means for detecting said product ions comprising a scintillation detector actuated by said ions.
  • said detecting means comprises a scintillator and a photomultiplier coupled thereto by an insulating light conductor.

Abstract

Trace components of a gaseous sample are separated at atmospheric pressure in a drift cell by producing ions of the trace gases through ion-molecule reactions and by separating the resultant product ions in accordance with drift velocity. A molecular beam, including product ions from the drift cell, passes through a transition region, where the ions are focused and separated from neutral molecules, to a mass analyzer. In the analyzer, the product ions are separated in accordance with mass and selectively passed to an ion counter. The mass analyzer and ion counter are maintained at high vacuum.

Description

o u United States aten 72] Inventors Martin J. Cohen West Palm Beach; David 1. Carroll, Lantana; Roger 1F. Wernlund, Lake Worth; Wallace D. Kllpatrlck, North Palm Beach, all of Fla. [21] App]. No. 828,402 [22] Filed May 27, 11969 [45] Patented Nov. 116, 19711 [73] Assignee Franklin GNO Corporation West Palm Beach, Fla.
[54] APPARATUS AND METRO FOR DETECTING 2,806,161 9/1957 Foster 250/41.91SR 2,944,146 7/1960 Schultz... 250/41 .9 R 3,041,453 6/1962 Daly 250/41.9 R 3,211,996 10/1965 FoxetaL. 250/41.9(l) 3,254,209 5/1966 Fite et a1 250/41.91SB FOREIGN PATENTS 1,230,714 9/1960 France 250/4l.9 (2) OTHER REFERENCES Vance et 211., Review of Scientific lnstruments; Vol. 34, No. 8; August, 1963, pp. 925- 927.
Primary ExaminerAnthony L. Birch Attorney-Raphael Semmes ABSTRACT: Trace components of a gaseous sample are separated at atmospheric pressure in a drift cell by producing ions of the trace gases through ion-molecule reactions and by separating the resultant product ions in accordance with drift velocity. A molecular beam, including product ions from the drift cell, passes through a transition region, where the ions are focused and separated from neutral molecules, to a mass analyzerv 1n the analyzer, the product ions are separated in accordance with mass and selectively passed to an ion counter. The mass analyzer and ion counter are maintained at high vacuum,
PATENTEnunv 16 new INVENTORS MARTIN J. COHEN DAVID L CARROLL ROG WAL ER F. WERNUJND LACE D. KILPATRICK a ATTOHN EV APPARATUS AND METHODS FOR DETECTING AND WENTIWING TRACE GASES BACKGROUND OF THE INVENTION This invention relates to apparatus and methods for detecting and identifying either positive or negative ions of trace gases in an ambient sample.
Prior techniques for the analysis of trace gases, such as gas chromatography or mass spectroscopy, are deficient in one or more of the following respects: (1) the necessity of obtaining discrete samples of the gas to be analyzed, (2) fragmentation of the parent material, (3) the requirement of long measurement time.
The copending application of Martin J. Cohen, David 1. Carroll, Roger P. Wernlund, and Wallace D. Kilpatnck, Ser. No. 777,964, filed Oct. 23, 1968, and entitled Apparatus and Methods for Separating, Concentrating, Detecting, and Measun'ng Trace Gases", discloses atechnique, termed Plasma Chromatography", by which measurements upon trace gases can be performed continuously at atmospheric pressure, without collecting discrete samples and without modification of the parent materials. Moreover, the measurements can be performed very rapidly (in seconds) and at high sensitivity (of the order of one part in for example). Succinctly stated, the system of that application involves the formation of primary or reactant ions from a reactant gas and the reaction of the primary ions with molecules of trace substances to form secondary or product ions, which may be concentrated, separated, detected, and measured by virtue of the velocity or mobility of the ions in an electric field. A significant advantage of the system is that measurements are preferably performed at or about atmospheric pressure. The resolution of the apparatus described in the copending application is, however, not as great as that of gas chromatography, for example, and therefore, some ambiguity may exist where it is desired to identify particular trace gas constituents of the sample.
BRIEF DESCRIPTION OF THE INVENTION It is accordingly a principal object of the present invention to provide apparatus and methods for measuring trace gases at atmospheric pressure, such as in ambient air, and yet to identify trace gas components with far greater accuracy than has heretofore been possible.
A further object of the invention is to provide apparatus and methods of the foregoing type which do not require the collection of discrete samples, which avoid modification of parent materials, and which operate rapidly and at high sensitivity.
Briefly stated, the present invention is concerned with a measurement technique in which ions of trace gases are formed as the product of ion-molecule reactions in a drift cell operated at atmospheric pressure. The product ions are separated in accordance with their drift velocity and are passed in a molecular beam to a mass analyzer, operated at high vacuum, via a transition region at which the ions are focused and the neutral molecules of the molecular beam are separated from the ions. Ions selected by the mass analyzer are counted or otherwise detected.
BRIEF DESCRIPTION OF THE DRAWING The invention will be further described in conjunction with the accompanying drawing, which illustrates preferred and exemplary embodiments, and wherein:
FIG, I is a diagrammatic perspective view of one form of the invention; and
FIG. 2 is a diagrammatic longitudinal sectional view of a second form of the invention.
DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. I of the drawing, apparatus in accordance with the invention comprises a Plasma Chromatograph I0, a mass analyzer I2 connected to the Plasma Chromatograph via a transition section I4, and an ion detector I6. The Plasma Chromatograph, which is shown quite diagrammatically in FIG. I, is illustrated in greater detail in FIG. 2. Such apparatus is disclosed in the aforesaid copending application, and, in an improved form, in the copending application of David I. Carroll, Martin J. Cohen, and Roger F. Wernlund, Ser. No. 780,851, filed Dec. 3, 1968, and entitled Apparatus and Methods for Separating, Detecting, and Measuring Trace Gases with Enhanced Resolution".
Broadly, the Plasma Chromatography technique involves the production of primary ions by subjecting the molecules of a host gas, such as air, to ionizing radiation, for example. The primary ions are subjected to an electric drift field, causing them to migrate in a predetermined. direction through a reaction space into which the sample or trace gas is introduced. The resultant collisions between the primary ions and the trace gas molecules produce secondary ions of the trace gas in much greater numbers than can be produced by mere electron attachment, for example, to the trace gas molecules. The secondary or product ions are also subjected to the drift field. Because the drift cell of the Plasma Chromatograph is operated (preferably at atmospheric pressure) so as to maintain the mean free path of the product ions much smaller than the dimensions of the cell, the ions reach statistical terminal velocity in the drift field dependent upon their mass and may be sorted in accordance with their velocity or mobility. Specific systems of the copending applications employ a pair of successively arranged ion shutter grids or gates for segregating the ion species in accordance with their drift time. The opening of the first gate is timed to pass a group of ions, which may comprise unreacted primary ions as well as secondary or product ions, and the opening of the second gate is timed to pass a portion of the group to an ion detection means.
In the Plasma Chromatography apparatus illustrated in FIG. 2 of the drawing (representative of FIG. II), a drift cell is employed which comprises part of an envelope II, of metal for example, having a sample inlet I3 and an outlet 26. The envelope contains a series of spaced electrodes. which may have parallel plane geometry, for example, and which may include a pair of principal electrodes C and A and a pair of shutter grids or ion gates GI and G2. If the apparatus is to be employed to detect negative ions, electrode C will be a cathode and electrode A will be an anode, while if positive ions are to be detected, the polarities will be reversed. The electrodes may be spaced-apart distances of the order of a few centimeters or less (for example, cathode to anode spacing of about 10 centimeters) and may have suitable lead wires passing through the envelope by means of insulators (not shown). Electrode C or the region of the envelope near this electrode is provided with an ionizing means, such as a photo emission source, a radioactive source, a multiple point or wire array (corona) source, or an RF ionization source. In the form shown, the ionizer I is a radioactive source, such as tritium foil. The foil may be placed at the end of the inlet tube I3 which exits through an opening in electrode C.
The grids GI and G2 may be of the parallel wire type. Alternate wires of each of the grids are connected together to form two separate groups, so that each shutter grid comprises two interdigitated subgrids of parallel wires. Adjacent elements of each grid are normally maintained at equal and opposite potentials relative to a grid average potential, and under these conditions, the shutter or gate is closed to the passage of electrically charged particles. The potential sources which provide the equal and opposite potentials just referred to may be considered to be part of grid drive circuits contained within the block I7. The components of this block are effective to drive the adjacent elements of each shutter grid to the same potential, the' grid average potential, at predetermined instants. The grids per se and the circuits for driving the same are known in the art and need no further elucidation.
Electrode A would, in the Plasma Chromatograph of the type disclosed in the aforesaid copending applications, serve as a collector plate connected to an output divide. In the present invention, this electrode also serves as an apertured partition to permit ions to exit from the drift chamber 18 in the envelope 11, the electrode being provided with a central aperture 19 for the passage of a molecular beam.
An electric drift field is provided between electrodes C and A. In the form shown, the source of drift field is a battery 20 connected across a resistor chain 22, taps of which provide static potentials for the electrodes contained within chamber 18. In the embodiment of the invention illustrated in FIG. 2, electrode A is connected to ground, as is the positive side of the battery 20, and the negative side of battery 20 is connected to electrode C. The grid average potential for grid G1 is provided by connecting each subgrid through a series resistor (not shown) to the same point on the resistor chain 22. The grid drive potentials are applied to the junctions of the series resistors and the subgrids, respectively. Grid G2 is similarly supplied. A series of guard rings 24 is provided along the perimeter of the envelope to maintain the uniformity of the electric field between the electrodes. The guard rings are also connected to successive points on the resistor chain. Suitable supports and spacers, such as quartz rods and tubes, may be employed to support the various electrodes within the envelope. The apparatus of the invention also preferably includes an additional inlet 15 through which a nonreactive buffering as, such as nitrogen, may be introduced into the envelope as described in copending application Ser. No. 780,851.
In an illustrative operation of the Plasma Chromatograph 10, air carrying a suitable ionizable gaseous trace substance, such as methane or SF flows into the chamber 18 by means of the inlet 13 and is exhausted through the outlet 26. Any suitable source of flow pressure, such as a fan, may be employed to move the carrier gas containing the trace substances. In the region adjacent to the ionizer 1, ions of the carrier or host gas or one or more of the main constituents thereof, such as oxygen, are formed under the influence of the radioactive source at this region. The primary ions may be negative oxygen ions, for example, formed by direct attachment of electrons to the oxygen molecules. The ions drift toward electrode A under the influence of the drift field. In the region between electrode C and grid G1, the primary ions formed at electrode C react with molecules of the trace vapors to convert these molecules to product ions. Further ionmolecule reactions are quenched by the nonreactive gas supplied by inlet 15.
During operation of the apparatus, shutter grid G1 is periodically opened to sample the products of the reaction and any other ion species present. The opening of grid Gl at a predetermined time and for a predetermined duration (for example, millisecond) constitutes a timed reference pulse during which a group of ions is passed into the ion mobility analysis region between GI and G2. As the ions drift from G] to G2 they become grouped or classified in accordance with the velocity (a function of ion mass) in the drift field. Because the mean free path of the ions in chamber 18 is much less than the chamber dimensions (by virtue of the relatively high-atmospheric pressure), statistical terminal velocity is reached. At a predetermined time, delayed relative to the opening of grid G1, grid G2 is opened for a predetermined duration to select a portion of the ion mobility spectrum within the region G1 to G2 for passage toward electrode A. Those ions which impinge upon electrode A produce an output current which may be measured by an electrometer (not shown). The output current varies in time according to the characteristic drift time of each species as the various species traverse the drift cell. The ions are nonnally detected as pulses and thereby permit a time display for the ion species present. By scanning the time of opening of grid G2 relative to G1, the entire drift spectrum may be displayed.
Returning now to FIG. 1, the Plasma Chromatograph 10 is assumed to be constructed and to operate like that of FIG. 2, rings 28 being a diagrammatic representation of the grids G1 and G2 and the guard rings 24 of FIG. 2. The product ions passed toward electrode A are sampled by the aperture 19, a
sample of the ions being passed through the aperture as part of a molecular beam or jetstream containing neutral gas molecules and product ions. The aperture operates under viscous flow conditions, the mean free path of ions radially of the aperture being small compared to the aperture diameter. The thickness of the thin wall-sampling aperture is less than the aperture diameter in order to minimize wall interaction with the ions transported through the aperture. The transition section 14 of the envelope 11 comprises a chamber 30 connected by a pipe 32 to a vacuum system for pumping out the chamber (to a vacuum of say 0.5 to 2 Torr). There is thus a supersonic expansion of the jetstream at the aperture 19 from the high-pressure (760 Torr) conditions in chamber 18 to the vacuum conditions in chamber 30.
The transition section transposes ions from an ambient pressure region to a substantially lower pressure region without substantial modification either of the quantity of the ions transferred or the species of the ions transferred. The centrally apertured electrodes 34 (aperture diameter 0.005 to 0.015 inch, for example) in the transition section are diagrammatic representations of conventional ion-focusing electrodes for focusing the product ions into a beam and for preventing dispersion of the ions within the transition region. Neutral molecules in this region are separated from the ion beam by virtue of the vacuum pumping. The series of apertures is radially transparent to gas velocities in the molecular beam and opaque to ion velocities in the molecular beam. Ion Species of the Plasma Chromatograph are preserved at all times, so that mass analysis is not subject to the extensive fragmentation found in conventional ion-source spectrometers. Further, the maximum number of ions present in the ambient atmosphere is extracted and introduced efficiently into the mass analyzer. High trace gas sensitivity is provided by concentration (focusing) of the charged carriers, but the fields are kept low enough to avoid changes in ion species.
The beam of ions passes from the transition region 14 to the mass analyzer 12 through an aperture 36 in an electrode A upon the wall of chamber 38, which constitutes a further portion of the envelope 11, an accelerating potential being applied between electrodes A and A. The input potential to the mass analyzer is set for the dual purpose of setting the ion velocity and reducing ion losses (analog to ion focusing). The mass analyzer is of a conventional type. The preferred quadrupole type (readily adapted to both positive and negative ions as well as ion counting), comprising the usual rectangular arrangement of elongated electrodes 40 is shown, although other types, such as time-of-flight, magnetic deflection, or RF separator, may be employed. An accelerating potential is applied between electrodes A' and A" at opposite ends of chamber 38. By virtue of the conventional operation of the mass analyzer, including variation of electrical parameters, as is well known in the art, the product ions are separated in accordance with their mass, and selected ions are passed to the ion detector 16 through an aperture 42 in electrode A" upon the wall of the detector chamber 44, which forms a further section of the envelope 1 1. Both the mass analyzer and detector sections are maintained at high vacuum by connection of the pipes 46 and 48 to a high-vacuum system. The premure in chamber 38 may be 10 Torr or less to reduce ion scattering. The mean free path of ions in chamber 38 is much longer than that in chamber 18 and is preferably substantially longer than the dimensions of the mass analyzer structure, so that the mass analyzer operates under molecular flow conditions. Fast pumping speeds for the neutral gas in the mass analyzer are essential. However, the sampling technique removes such small quantities of gas from chamber 18 that measurements in the Plasma Chromatography drift cell can be accomplished under essentially static conditions.
In order to maintain high sensitivity, the detector is preferably an ion-counting device capable of registering l to 10,000 counts per second. In the form shown, the detector employs an electron multiplier including a series of dynodes 50 in a conventional arrangement for producing secondary electrons in response to the product ions passed through aperture 42. The output electrode of the detector may be condenser-coupled to a conventional pulse-counting device. Pumpout and vacuum conditioning of the detector is desirable to maintain surface conditions most suitable for high secondary electron yields and thus high sensitivity.
The Plasma Chromatograph is capable of detecting trace gases with high sensitivity. The produce ion output of the Plasma Chromatograph may be influenced by varying the ratio of the drift field to the ambient pressure within chamber 18, by controlling the timing of grid G2 relative to grid G1, and by selecting the reactant gases from'which the primary ions are formed. Through conventional control of the mass analyzer 112, a particular species of product ion may be passed to the detector and identified (by mass number) with great accuracy. The focusing structure provided in the transition section M ensures that the ions are maintained as a beam for application to the mass analyzer, and the pumpout at this region reduces scattering of the beam due to collision with background gases. Ion-focusing structure may also be provided between grid G2 and electrode A to collimate ions for application to the aperture 119.
An ion-accelerating potential out of the mass analyzer of about 2,500 volts (between electrode A" and A) is provided to gain enough energy to produce electrons at the first dynode of the detector 16 by secondary emission, for multiplication by further secondary emission in the multiplier structure. The multiplier structure needs an electronaccelerating potential of about 2,000 volts, which is provided between the input and output electrodes thereof.
For positive ions electrode A may be grounded, and electrode C may be 1,000 volts positive relative to ground. Electrode A may be 100 volts negative relative to ground, and electrode A" may be 5,000 volts negative relative to ground. The output electrode of the multiplier may be 2,000 volts positive relative to the input electrode thereof. For negative ions the polarities, except in the multiplier, are reversed. Thus, the multiplier output electrode will be +7,000 volts relative to ground. DC blocking is provided by virtue of the coupling capacitor from the multiplier anode to the output circuit.
FIG. 2 illustrates an embodiment of the invention with a modified transition section and a modified detector section. Although shown together for illustrative purposes, the modified sections may be substituted individually for the corresponding sections of FIG. 1.
The embodiment of FIG. 2 employs a scintillation detector. Each ion from the quadrupole structure 40 impinges on a scintillator 52, which may be a conventional plastic, anthracene, or phosphor type, for example, or which may utilize a semiconductor detector element. The scintillator may be biased at 5,000 volts relative to ground, for example, by means of a DC supply represented by the battery 54. The polarity of the battery as shown is for detecting negative ions and would be reversed for detecting positive ions. Scintillations from the detector element 52 are passed by a quartz light pipe 56 to a suitably housed photomultiplier 58 (protected from ambient light). The quartz light pipe provides optical conduction as well as electrical insulation. The scintillator can be operated "hot" and the photomultiplier at normal potentials with the anode substantially at ground. An integrated output may be taken from the output resistor 60 representing the input impedance of electrometer or of a pulse counter.
In certain cases it is desired that the quadrupole structure be grounded, as shown in FIG. 2. To achieve this objective, another disclike electrode 62 with a central aperture 64 is pro vided adjacent to electrode A. Aperture M may be 10 to 50 times the diameter of aperture 19, for example. Aperture 64 is operated at a repulsive potential relative to aperture 19 of say l 00 volts for negative ions. In a vacuum this electrode would prevent ions from passing through the aperture 64. However, under the operating conditions of the invention, with a high pressure in the chamber 18 relative to the pressure in the transition chamber 30', a high-velocity gas stream mixed with ions issues from the aperture 64. This gas stream, collisions, carries the ions through the aperture to the point where the grounded quadrupole structure can attract them. Thus, advantage is taken of the viscous drag of the highvelocity (sonic) gas stream to carry the ions across the potential barrier into the region where, at lower pressure, they are focused into the mass analyzer.
FIG. 2 also illustrates the utilization of a skimmer 68 for ion focusing and separation of neutral molecules. The skimmer is a conical electrode with a central aperture 70 and is located downstream of electrode 62 by say 1 cm. or less. The diameter of aperture 70 may be of the order ofa mean free path length. For negative ions, the skimmer may be operated at a potential of say -30 volts relative to ground. The skimmer 68, electrode 62 (and the other "hot" electrodes described) are of course isolated from the envelope (if metal) by suitable insulators (not shown). Further electrodes may be placed between the skimmer and the mass analyzer rods to focus ions into the mass analyzer in accordance with conventional techniques. With the pressure in chamber 18 at atmospheric (760 Torr), the pressure in transition chamber 30 may be 0.5 to 2 Torr, while the pressure in chamber 38' may be 110" Torr. Chambers 30' and 38 are connected to the high-vacuum system by piper 32 and 46'. In the embodiment of FIG. 2, the detector operates efficiently at the same pressure as the mass analyzer and need not be placed in a separate chamber. The transition sections of FIGS. l and 2 may be subdivided into successive sections, which may be separately pumped to successively lower pressures, and the divider walls may be constituted by skimmers of the type shown in FIG. 2, for example.
The invention permits identification of the parent trace gas ion species by mobility, by virtue of the Plasma Chromatograph, and more selective identification by mass number, by virtue of the mass analyzer. The apparatus as a whole detects the trace gas more sensitively than a mass analyzer alone and identifies species more accurately than a Plasma Chromatograph alone. The Plasma Chromatograph, while preferably operated at atmospheric pressure, may be operated above or below atmospheric pressure (assuming that the aforesaid mean free path length conditions are maintained), and the pressures of the mass analyzer and detector are independently chosen. The detector counts ions under gas contamination conditions uncommon to the present state of the art. Output from the detector may be either specific counts or a continuous signal (count rate).
The invention may be used to determine ion-molecule reaction rates (particularly where Plasma Chromatography cell pressures are changed) and to perform measurements of elementary particle collision parameters, such as electron attachment cross section and polarizability.
The charged particles detected may be charged atoms or clusters, as well as charged molecules, and the terms ion" and ion-molecule reactions" are intended as comprising such particles.
While preferred embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that changes can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims.
The invention claimed is:
1. A method of detecting trace gas which comprises forming primary ions at a localized region of a first chamber, forming product ions of different mobility at a further region of said first chamber by ion-molecule reactions involving said primary ions and molecules of said trace gas, applying a drift field to said ions and causing them to drift toward a second chamber, maintaining the pressure in said first chamber at a high enough level such that the mean free path of the ions in said first chamber is very small compared to the dimensions of said first chamber and such that said ions reach substantially constant statistical terminal velocity in said first chamber dependent upon their mass and separate in accordance with their mobility, passing saidproduct ions to said second chamber, mainby multiple taining the pressure in said second chamber at a substantially lower level than that in said first chamber such that the mean free path of the product ions in said second chamber is substantially longer than the mean free path in said first chamber, analyzing said product ions in said second chamber in accordance with their mass, and detecting at least some of the analyzed ions.
2. A method in accordance with claim 1, in which the pressure in said first chamber is maintained at about atmospheric pressure.
3. A method in accordance with claim 1, in which a gas inert and nonreactive with respect to said ions is introduced to said first chamber.
4. A method in accordance with claim 1, in which the product ions are formed into a beam before being passed to said second chamber.
5. A method in accordance with claim 1, in which the product ions are detected in a third chamber.
6. A method in accordance with claim in which said product ions are detected in said third chamber by generating secondary electrons in response thereto.
7. A method in accordance with claim 5, in which said product ions are accelerated in passing from said second chamber to said third chamber.
8. A method in accordance with claim 5, in which said product ions are detected individually in said third chamber.
9. A method in accordance with claim 1, in which the product ions formed in said first chamber are divided by ion gating.
10. A method in accordance with claim 1, in which the product ions are focused into a beam before being passed to said second chamber.
11. A method in accordance with claim I, in which said product ions are transposed from said first chamber to said second chamber as part of a supersonic jetstream molecular beam, and in which the neutral molecules of said beam are separated from product ions of said beam before said product ions are passed to said second chamber.
12. A method in accordance with claim 1, in which said product ions are detected by producing scintillations therefrom.
13. A method in accordance with claim 1, in which said primary ions are formed by ionizing a reactant gas.
14. A method in accordance with claim 13, in which said trace gas and said reactant gas are supplied to said first chamber as a gaseous sample.
15. Apparatus for performing ion measurements, which comprises an envelope having successive chambers, means within the first of said chambers for forming primary ions at a localized region of said first chamber and for forming difi'erent mobility product ions at a further region of said first chamber by ion-molecule reactions involving said primary ions and molecules of a sample gas, means for subjecting said ions to a drift field and causing them to drift toward a second chamber of said envelope means for maintaining the pressure in said first chamber at a high enough level such that the mean free path of the ions in said first chamber is very much smaller than the chamber dimensions and such that said ions reach substantially constant statistical terminal velocity in said first chamber dependent upon their mass and separate in accordance with their mobility, means for passing product ions from said first chamber to said second chamber, means for maintaining the pressure in said second chamber substantially lower than the pressure in said first chamber such that the mean free path of said product ions in said second chamber is substantially longer than that in said first chamber, means for separating said product ions in said second chamber in accordance with their mass, and means for detecting at least some of the lastmentioned product ions.
16. Apparatus in accordance with claim 15, said means for passing said product ions from said first chamber to said second chamber comprising an intermediate chamber having means for maintaining the pressure therein at a level between the pressures of said first and secOndchambers.
1 Apparatus in accordance with claim 16. and intermediate chamber having means associated therewith for forming product ions into a beam.
18. Apparatus in accordance with claim 16, said intermediate chamber having means associated therewith for passing product ions thereto from said first chamber as part of a supersonic jetstream molecular beam and having means for separating neutral molecules of said beam from said product ions.
19. Apparatus in accordance with claim 16, said intermediate chamber being coupled to said first chamber by a viscous flow aperture.
20. Apparatus in accordance with claim 16, said intermediate chamber having a series of ion-focusing electrodes therein.
21. Apparatus in accordance with claim 15, wherein said first chamber has means for producing primary ions by ionizing a reactant gas.
22. Apparatus in accordance with claim 15, wherein said first chamber has means for introducing therein a gas inert and nonreactive with respect to said ions.
23. Apparatus in accordance with claim 17, said separating means in said second chamber comprising a mass analyzer.
24. Apparatus in accordance with claim 23, said mass analyzer being of the quadrupole type.
25. Apparatus in accordance with claim 15, said ion-detecting means comprising an electron multiplier actuated by said product ions.
26. Apparatus in accordance with claim 15, said first chamber having ion-gating means for passing a group of ions from a first region of said first chamber to a second region thereof and having further ion-gating means for passing a portion of the group of ions from the second region to a third region of said first chamber.
27. Apparatus in accordance with claim 15, said first chamber having a pair of electrodes adjacent to opposite ends thereof and having means for applying said drift field between said electrodes.
28. Apparatus in accordance with claim 15, said means for passing said product ions from said first chamber to said second chamber comprising at least a pair of apertured electrodes.
29. Apparatus in accordance with claim 15, said means for passing said product ions from said first chamber to said second chamber comprising an apertured electrode which diverges from said first chamber toward said second chamber.
30. Apparatus in accordance with claim 15, said means for detecting said product ions comprising a scintillation detector actuated by said ions.
31. Apparatus in accordance with claim 15, further comprising means for accelerating product ions from said first chamber to said second chamber, and means for accelerating product ions from said second chamber to a third chamber for detection.
32. Apparatus in accordance with claim 15, further comprising viscous flow apertured electrode means for decelerating said product ions as the ions pass from said first chamber toward said second chamber, and further comprising means for thereafter accelerating said ions.
33. Apparatus in accordance with claim 15, wherein said detecting means comprises a scintillator and a photomultiplier coupled thereto by an insulating light conductor.
34. Apparatus in accordance with claim 15, wherein said means for subjecting said ions to a drifi field comprises a pair of spaced electrodes in said first chamber, said means for forming primary ions comprises a continuous radioactive source adjacent to one of said electrodes, and said means for passing product ions from said first chamber to said second chamber comprises a viscous flow aperture in the other of said electrodes, said further region of said first chamber in which said ion-molecules reactions occur being located between said electrodes.

Claims (33)

  1. 2. A method in accordance with claim 1, in which the pressure in said first chamber is maintained at about atmospheric pressure.
  2. 3. A method in accordance with claim 1, in Which a gas inert and nonreactive with respect to said ions is introduced to said first chamber.
  3. 4. A method in accordance with claim 1, in which the product ions are formed into a beam before being passed to said second chamber.
  4. 5. A method in accordance with claim 1, in which the product ions are detected in a third chamber.
  5. 6. A method in accordance with claim 5, in which said product ions are detected in said third chamber by generating secondary electrons in response thereto.
  6. 7. A method in accordance with claim 5, in which said product ions are accelerated in passing from said second chamber to said third chamber.
  7. 8. A method in accordance with claim 5, in which said product ions are detected individually in said third chamber.
  8. 9. A method in accordance with claim 1, in which the product ions formed in said first chamber are divided by ion gating.
  9. 10. A method in accordance with claim 1, in which the product ions are focused into a beam before being passed to said second chamber.
  10. 11. A method in accordance with claim 1, in which said product ions are transposed from said first chamber to said second chamber as part of a supersonic jetstream molecular beam, and in which the neutral molecules of said beam are separated from product ions of said beam before said product ions are passed to said second chamber.
  11. 12. A method in accordance with claim 1, in which said product ions are detected by producing scintillations therefrom.
  12. 13. A method in accordance with claim 1, in which said primary ions are formed by ionizing a reactant gas.
  13. 14. A method in accordance with claim 13, in which said trace gas and said reactant gas are supplied to said first chamber as a gaseous sample.
  14. 15. Apparatus for performing ion measurements, which comprises an envelope having successive chambers, means within the first of said chambers for forming primary ions at a localized region of said first chamber and for forming different mobility product ions at a further region of said first chamber by ion-molecule reactions involving said primary ions and molecules of a sample gas, means for subjecting said ions to a drift field and causing them to drift toward a second chamber of said envelope, means for maintaining the pressure in said first chamber at a high enough level such that the mean free path of the ions in said first chamber is very much smaller than the chamber dimensions and such that said ions reach substantially constant statistical terminal velocity in said first chamber dependent upon their mass and separate in accordance with their mobility, means for passing product ions from said first chamber to said second chamber, means for maintaining the pressure in said second chamber substantially lower than the pressure in said first chamber such that the mean free path of said product ions in said second chamber is substantially longer than that in said first chamber, means for separating said product ions in said second chamber in accordance with their mass, and means for detecting at least some of the last-mentioned product ions.
  15. 16. Apparatus in accordance with claim 15, said means for passing said product ions from said first chamber to said second chamber comprising an intermediate chamber having means for maintaining the pressure therein at a level between the pressures of said first and second chambers.
  16. 17. Apparatus in accordance with claim 16, said intermediate chamber having means associated therewith for forming product ions into a beam.
  17. 18. Apparatus in accordance with claim 16, said intermediate chamber having means associated therewith for passing product ions thereto from said first chamber as part of a supersonic jetstream molecular beam and having means for separating neutral molecules of said beam from said product ions.
  18. 19. Apparatus in accordance with claim 16, said intermediate chamber being coupled to said first chamber by a viscous flow aperture.
  19. 20. Apparatus in accordance with claim 16, said intermediAte chamber having a series of ion-focusing electrodes therein.
  20. 21. Apparatus in accordance with claim 15, wherein said first chamber has means for producing primary ions by ionizing a reactant gas.
  21. 22. Apparatus in accordance with claim 15, wherein said first chamber has means for introducing therein a gas inert and nonreactive with respect to said ions.
  22. 23. Apparatus in accordance with claim 17, said separating means in said second chamber comprising a mass analyzer.
  23. 24. Apparatus in accordance with claim 23, said mass analyzer being of the quadrupole type.
  24. 25. Apparatus in accordance with claim 15, said ion-detecting means comprising an electron multiplier actuated by said product ions.
  25. 26. Apparatus in accordance with claim 15, said first chamber having ion-gating means for passing a group of ions from a first region of said first chamber to a second region thereof and having further ion-gating means for passing a portion of the group of ions from the second region to a third region of said first chamber.
  26. 27. Apparatus in accordance with claim 15, said first chamber having a pair of electrodes adjacent to opposite ends thereof and having means for applying said drift field between said electrodes.
  27. 28. Apparatus in accordance with claim 15, said means for passing said product ions from said first chamber to said second chamber comprising at least a pair of apertured electrodes.
  28. 29. Apparatus in accordance with claim 15, said means for passing said product ions from said first chamber to said second chamber comprising an apertured electrode which diverges from said first chamber toward said second chamber.
  29. 30. Apparatus in accordance with claim 15, said means for detecting said product ions comprising a scintillation detector actuated by said ions.
  30. 31. Apparatus in accordance with claim 15, further comprising means for accelerating product ions from said first chamber to said second chamber, and means for accelerating product ions from said second chamber to a third chamber for detection.
  31. 32. Apparatus in accordance with claim 15, further comprising viscous flow apertured electrode means for decelerating said product ions as the ions pass from said first chamber toward said second chamber, and further comprising means for thereafter accelerating said ions.
  32. 33. Apparatus in accordance with claim 15, wherein said detecting means comprises a scintillator and a photomultiplier coupled thereto by an insulating light conductor.
  33. 34. Apparatus in accordance with claim 15, wherein said means for subjecting said ions to a drift field comprises a pair of spaced electrodes in said first chamber, said means for forming primary ions comprises a continuous radioactive source adjacent to one of said electrodes, and said means for passing product ions from said first chamber to said second chamber comprises a viscous flow aperture in the other of said electrodes, said further region of said first chamber in which said ion-molecules reactions occur being located between said electrodes.
US828402A 1969-05-27 1969-05-27 Apparatus and methods for detecting and identifying trace gases Expired - Lifetime US3621240A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US82840269A 1969-05-27 1969-05-27

Publications (1)

Publication Number Publication Date
US3621240A true US3621240A (en) 1971-11-16

Family

ID=25251700

Family Applications (1)

Application Number Title Priority Date Filing Date
US828402A Expired - Lifetime US3621240A (en) 1969-05-27 1969-05-27 Apparatus and methods for detecting and identifying trace gases

Country Status (1)

Country Link
US (1) US3621240A (en)

Cited By (70)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3740149A (en) * 1972-02-02 1973-06-19 Gen Electric Method and apparatus for measuring size distribution of particles using a three-dimensional alternating current electric field
US3831025A (en) * 1972-02-28 1974-08-20 Bendix Corp Ion source for providing a supply of charged particles having a controlled kinetic energy distribution
US3845301A (en) * 1972-05-10 1974-10-29 Franklin Gno Corp Apparatus and methods employing ion analysis apparatus with enhanced gas flow
US3920987A (en) * 1972-09-14 1975-11-18 Stanford Research Inst Method and system for detecting explosives
US3970849A (en) * 1973-12-20 1976-07-20 U.S. Philips Corporation Device for mass analysis and structure analysis of a surface layer by means of ion scattering
US3984692A (en) * 1972-01-04 1976-10-05 Arsenault Guy P Ionization apparatus and method for mass spectrometry
US4005291A (en) * 1972-01-04 1977-01-25 Massachusetts Institute Of Technology Ionization method for mass spectrometry
US4059761A (en) * 1975-03-27 1977-11-22 Trw Inc. Separation of isotopes by time of flight
US4368388A (en) * 1975-12-15 1983-01-11 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Detection of polar vapors
US4459481A (en) * 1982-04-26 1984-07-10 The United States Of America As Represented By The United States Department Of Energy Ion source for high-precision mass spectrometry
US4472631A (en) * 1982-06-04 1984-09-18 Research Corporation Combination of time resolution and mass dispersive techniques in mass spectrometry
US4719349A (en) * 1986-05-27 1988-01-12 The United States Of America As Represented By The Department Of Health And Human Services Electrochemical sample probe for use in fast-atom bombardment mass spectrometry
US5070240A (en) * 1990-08-29 1991-12-03 Brigham Young University Apparatus and methods for trace component analysis
US5083019A (en) * 1990-08-21 1992-01-21 Environmental Technologies Group, Inc. Preconcentrator for ion mobility spectrometer
US5200614A (en) * 1992-01-16 1993-04-06 Ion Track Instruments, Inc. Ion mobility spectrometers
US5670378A (en) * 1995-02-23 1997-09-23 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method for trace oxygen detection
US5854485A (en) * 1996-08-01 1998-12-29 Bergmann; Thorald Horst MS/MS time-of-flight mass-spectrometer with collision cell
WO2000070335A2 (en) * 1999-05-17 2000-11-23 Advanced Research & Technology Institute Ion mobility and mass spectrometer
US20020134933A1 (en) * 2001-03-20 2002-09-26 Ion Track Instruments Llc Enhancements to ion mobility spectrometers
US6495823B1 (en) 1999-07-21 2002-12-17 The Charles Stark Draper Laboratory, Inc. Micromachined field asymmetric ion mobility filter and detection system
US6498342B1 (en) 1997-06-02 2002-12-24 Advanced Research & Technology Institute Ion separation instrument
US20030052263A1 (en) * 2001-06-30 2003-03-20 Sionex Corporation System for collection of data and identification of unknown ion species in an electric field
US20030070913A1 (en) * 2001-08-08 2003-04-17 Sionex Corporation Capacitive discharge plasma ion source
US20030146759A1 (en) * 2000-04-27 2003-08-07 Vladimir Bashkirov Nanodosimeter based on single ion detection
US6690004B2 (en) 1999-07-21 2004-02-10 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray-augmented high field asymmetric ion mobility spectrometry
US20040094704A1 (en) * 2002-04-12 2004-05-20 Sionex Corporation Method and apparatus for control of mobility-based ion species identification
US20040094702A1 (en) * 1997-06-02 2004-05-20 Clemmer David E. Instrument for separating ions in time as functions of preselected ion mobility and ion mass
US6806463B2 (en) 1999-07-21 2004-10-19 The Charles Stark Draper Laboratory, Inc. Micromachined field asymmetric ion mobility filter and detection system
US6815669B1 (en) 1999-07-21 2004-11-09 The Charles Stark Draper Laboratory, Inc. Longitudinal field driven ion mobility filter and detection system
US6815668B2 (en) 1999-07-21 2004-11-09 The Charles Stark Draper Laboratory, Inc. Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry
US20040232325A1 (en) * 2001-08-14 2004-11-25 Sionex Corporation Pancake spectrometer
US20050029449A1 (en) * 1999-07-21 2005-02-10 Miller Raanan A. System for trajectory-based ion species identification
US20050040330A1 (en) * 2001-06-30 2005-02-24 Kaufman Lawrence A. System for DMS peak resolution
US20050051719A1 (en) * 1999-07-21 2005-03-10 Sionex Corporation Systems for differential ion mobility analysis
US20050092914A1 (en) * 2002-10-12 2005-05-05 Sionex Corporation NOx monitor using differential mobility spectrometry
US20050133716A1 (en) * 1999-07-21 2005-06-23 Miller Raanan A. Explosives detection using differential ion mobility spectrometry
US20050139762A1 (en) * 2003-11-25 2005-06-30 Sionex Corporation Mobility based apparatus and methods using dispersion characteristics, sample fragmentation, and/or pressure control to improve analysis of a sample
US20050167583A1 (en) * 2003-12-18 2005-08-04 Sionex Corporation Methods and apparatus for enhanced ion based sample detection using selective pre-separation and amplification
US20050230616A1 (en) * 2004-02-02 2005-10-20 Sionex Corporation Compact sample analysis systems and related methods of using combined chromatography and mobility spectrometry techniques
US20050253061A1 (en) * 2004-04-28 2005-11-17 Sionex Corporation Systems and methods for ion species analysis with enhanced condition control and data interpretation
US7091481B2 (en) 2001-08-08 2006-08-15 Sionex Corporation Method and apparatus for plasma generation
US7098449B1 (en) 1999-07-21 2006-08-29 The Charles Stark Draper Laboratory, Inc. Spectrometer chip assembly
US20060222562A1 (en) * 2004-12-03 2006-10-05 Sionex Corporation Method and apparatus for enhanced ion based sample filtering and detection
US20060219892A1 (en) * 2003-03-07 2006-10-05 Andreas Walte Method and arrangement for detecting harmful substances
US7122794B1 (en) 2002-02-21 2006-10-17 Sionex Corporation Systems and methods for ion mobility control
US20070029477A1 (en) * 2005-04-29 2007-02-08 Sionex Corporation Compact gas chromatography and ion mobility based sample analysis systems, methods, and devices
EP1764825A1 (en) * 1997-06-02 2007-03-21 Indiana University Research and Technology Corporation Hybrid ion mobility and mass spectrometer
US20070158546A1 (en) * 2006-01-11 2007-07-12 Lock Christopher M Fragmenting ions in mass spectrometry
US20070272852A1 (en) * 2006-01-26 2007-11-29 Sionex Corporation Differential mobility spectrometer analyzer and pre-filter apparatus, methods, and systems
US7399958B2 (en) 1999-07-21 2008-07-15 Sionex Corporation Method and apparatus for enhanced ion mobility based sample analysis using various analyzer configurations
US20090032695A1 (en) * 2006-06-09 2009-02-05 Kaye William J Miniaturized Ion Mobility Spectrometer
US20090114811A1 (en) * 2007-11-06 2009-05-07 Jurgen Landgraf Ion mobility spectrometer and method for operation
US20090114812A1 (en) * 2007-11-06 2009-05-07 Jurgen Landgraf Ion mobility spectrometer with substance collector
US20090127457A1 (en) * 2005-02-09 2009-05-21 Roger Guevremont Apparatus and method for an electro-acoustic ion transmittor
US7550717B1 (en) 2006-11-30 2009-06-23 Thermo Finnigan Llc Quadrupole FAIMS apparatus
DE102008005281A1 (en) 2008-01-19 2009-07-30 Airsense Analytics Gmbh Method and device for the detection and identification of gases
US7579589B2 (en) 2005-07-26 2009-08-25 Sionex Corporation Ultra compact ion mobility based analyzer apparatus, method, and system
WO2009112001A1 (en) 2008-03-10 2009-09-17 Airsense Analytics Gmbh Method and device for the detection and identification of gases in airplane interior spaces
US7714284B2 (en) 2001-06-30 2010-05-11 Sionex Corporation Methods and apparatus for enhanced sample identification based on combined analytical techniques
US20110220794A1 (en) * 2010-02-12 2011-09-15 Yair Censor Systems and methodologies for proton computed tomography
EP2428797A1 (en) 2010-09-14 2012-03-14 Airsense Analytics GmbH Method and device for identifying and detecting gases by means of ion mobility spectrometry
EP2428796A1 (en) 2010-09-09 2012-03-14 Airsense Analytics GmbH Method and device for identifying and ionising gases by means of UV-radiation and electrons
US8217344B2 (en) 2007-02-01 2012-07-10 Dh Technologies Development Pte. Ltd. Differential mobility spectrometer pre-filter assembly for a mass spectrometer
US8735805B2 (en) 2004-11-04 2014-05-27 Micromass Uk Limited Mass spectrometer
US8841602B2 (en) 2011-03-07 2014-09-23 Loma Linda University Medical Center Systems, devices and methods related to calibration of a proton computed tomography scanner
US9084887B2 (en) 2009-02-05 2015-07-21 Loma Linda University Medical Center Proton scattering analysis system
US9213107B2 (en) 2009-10-01 2015-12-15 Loma Linda University Medical Center Ion induced impact ionization detector and uses thereof
EP3106867A1 (en) 2015-06-19 2016-12-21 Airsense Analytics GmbH Method and device for identifying gases
EP3457125A1 (en) 2017-09-14 2019-03-20 Airsense Analytics GmbH Device and method for detecting hazardous gases
US11658020B2 (en) 2020-11-24 2023-05-23 Inficon, Inc. Ion source assembly with multiple ionization volumes for use in a mass spectrometer

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2686880A (en) * 1951-10-23 1954-08-17 Atomic Energy Commission Isotope separator
US2806161A (en) * 1952-07-08 1957-09-10 Jr John S Foster Coasting arc ion source
US2944146A (en) * 1955-04-13 1960-07-05 Gen Electric Mass spectrometer
FR1230714A (en) * 1958-06-07 1960-09-19 Atlas Werke Ag Method and device for ion separation, in particular for mass spectrometry
US3041453A (en) * 1959-07-31 1962-06-26 Atomic Energy Authority Uk Positive ion detector
US3211996A (en) * 1960-12-05 1965-10-12 Westinghouse Electric Corp Apparatus for detecting electronegative gases in a mixture of gases
US3254209A (en) * 1962-11-29 1966-05-31 Gen Dynamics Corp Method and apparatus for increasing the ionization of impurity ions in a mass spectrometer

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2686880A (en) * 1951-10-23 1954-08-17 Atomic Energy Commission Isotope separator
US2806161A (en) * 1952-07-08 1957-09-10 Jr John S Foster Coasting arc ion source
US2944146A (en) * 1955-04-13 1960-07-05 Gen Electric Mass spectrometer
FR1230714A (en) * 1958-06-07 1960-09-19 Atlas Werke Ag Method and device for ion separation, in particular for mass spectrometry
US3041453A (en) * 1959-07-31 1962-06-26 Atomic Energy Authority Uk Positive ion detector
US3211996A (en) * 1960-12-05 1965-10-12 Westinghouse Electric Corp Apparatus for detecting electronegative gases in a mixture of gases
US3254209A (en) * 1962-11-29 1966-05-31 Gen Dynamics Corp Method and apparatus for increasing the ionization of impurity ions in a mass spectrometer

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Vance et al., Review of Scientific Instruments; Vol. 34, No. 8; August, 1963, pp. 925 927. *

Cited By (161)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3984692A (en) * 1972-01-04 1976-10-05 Arsenault Guy P Ionization apparatus and method for mass spectrometry
US4005291A (en) * 1972-01-04 1977-01-25 Massachusetts Institute Of Technology Ionization method for mass spectrometry
US3740149A (en) * 1972-02-02 1973-06-19 Gen Electric Method and apparatus for measuring size distribution of particles using a three-dimensional alternating current electric field
US3831025A (en) * 1972-02-28 1974-08-20 Bendix Corp Ion source for providing a supply of charged particles having a controlled kinetic energy distribution
US3845301A (en) * 1972-05-10 1974-10-29 Franklin Gno Corp Apparatus and methods employing ion analysis apparatus with enhanced gas flow
US3920987A (en) * 1972-09-14 1975-11-18 Stanford Research Inst Method and system for detecting explosives
US3970849A (en) * 1973-12-20 1976-07-20 U.S. Philips Corporation Device for mass analysis and structure analysis of a surface layer by means of ion scattering
US4059761A (en) * 1975-03-27 1977-11-22 Trw Inc. Separation of isotopes by time of flight
US4368388A (en) * 1975-12-15 1983-01-11 The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Detection of polar vapors
US4459481A (en) * 1982-04-26 1984-07-10 The United States Of America As Represented By The United States Department Of Energy Ion source for high-precision mass spectrometry
US4472631A (en) * 1982-06-04 1984-09-18 Research Corporation Combination of time resolution and mass dispersive techniques in mass spectrometry
US4719349A (en) * 1986-05-27 1988-01-12 The United States Of America As Represented By The Department Of Health And Human Services Electrochemical sample probe for use in fast-atom bombardment mass spectrometry
US5083019A (en) * 1990-08-21 1992-01-21 Environmental Technologies Group, Inc. Preconcentrator for ion mobility spectrometer
WO1992004728A1 (en) * 1990-08-29 1992-03-19 Brigham Young University Apparatus and methods for trace component analysis
US5070240A (en) * 1990-08-29 1991-12-03 Brigham Young University Apparatus and methods for trace component analysis
US5200614A (en) * 1992-01-16 1993-04-06 Ion Track Instruments, Inc. Ion mobility spectrometers
US5670378A (en) * 1995-02-23 1997-09-23 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Method for trace oxygen detection
US5854485A (en) * 1996-08-01 1998-12-29 Bergmann; Thorald Horst MS/MS time-of-flight mass-spectrometer with collision cell
US6323482B1 (en) 1997-06-02 2001-11-27 Advanced Research And Technology Institute, Inc. Ion mobility and mass spectrometer
EP1764825A1 (en) * 1997-06-02 2007-03-21 Indiana University Research and Technology Corporation Hybrid ion mobility and mass spectrometer
US6498342B1 (en) 1997-06-02 2002-12-24 Advanced Research & Technology Institute Ion separation instrument
US7077944B2 (en) 1997-06-02 2006-07-18 Indiana University Research And Technology Corporation Instrument for separating ions in time as functions of preselected ion mobility and ion mass
US6960761B2 (en) 1997-06-02 2005-11-01 Advanced Research & Technology Institute Instrument for separating ions in time as functions of preselected ion mobility and ion mass
US6559441B2 (en) 1997-06-02 2003-05-06 Advanced Research & Technology Institute Ion separation instrument
US20040094702A1 (en) * 1997-06-02 2004-05-20 Clemmer David E. Instrument for separating ions in time as functions of preselected ion mobility and ion mass
WO2000070335A3 (en) * 1999-05-17 2001-07-05 Advanced Res & Tech Inst Ion mobility and mass spectrometer
AU769697B2 (en) * 1999-05-17 2004-01-29 Indiana University Research And Technology Corporation Ion mobility and mass spectrometer
WO2000070335A2 (en) * 1999-05-17 2000-11-23 Advanced Research & Technology Institute Ion mobility and mass spectrometer
US7176453B2 (en) 1999-07-21 2007-02-13 The Charles Stark Draper Laboratory, Inc. Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry
US7435950B2 (en) 1999-07-21 2008-10-14 The Charles Stark Draper Laboratory, Inc. Micromachined field asymmetric ion mobility filter and detection system
US8410432B2 (en) 1999-07-21 2013-04-02 Dh Technologies Development Pte. Ltd. Method and apparatus for enhanced ion mobility based sample analysis using various analyzer configurations
US20070228269A1 (en) * 1999-07-21 2007-10-04 Sionex Corporation Systems for differential ion mobility analysis
US20040124350A1 (en) * 1999-07-21 2004-07-01 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray augmented high field asymmetric ion mobility spectrometry
US7262407B2 (en) 1999-07-21 2007-08-28 Sionex Corporation Explosives detection using differential mobility spectrometry
US6690004B2 (en) 1999-07-21 2004-02-10 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray-augmented high field asymmetric ion mobility spectrometry
US6806463B2 (en) 1999-07-21 2004-10-19 The Charles Stark Draper Laboratory, Inc. Micromachined field asymmetric ion mobility filter and detection system
US6815669B1 (en) 1999-07-21 2004-11-09 The Charles Stark Draper Laboratory, Inc. Longitudinal field driven ion mobility filter and detection system
US6815668B2 (en) 1999-07-21 2004-11-09 The Charles Stark Draper Laboratory, Inc. Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry
US7241989B2 (en) 1999-07-21 2007-07-10 Sionex Corp. Systems for differential ion mobility analysis
US20040240843A1 (en) * 1999-07-21 2004-12-02 The Charles Stark Draper Laboratory, Inc. Longitudinal field driven ion mobility filter and detection system
US20050017163A1 (en) * 1999-07-21 2005-01-27 The Charles Stark Draper Laboratory, Inc. Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry
US20050023457A1 (en) * 1999-07-21 2005-02-03 The Charles Stark Draper Laboratory, Inc. Micromachined field asymmetric ion mobility filter and detection system
US20050029449A1 (en) * 1999-07-21 2005-02-10 Miller Raanan A. System for trajectory-based ion species identification
US20050029443A1 (en) * 1999-07-21 2005-02-10 The Charles Stark Draper Laboratory, Inc. Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry
US7355170B2 (en) 1999-07-21 2008-04-08 Sionex Corporation Systems for differential ion mobility analysis
US20050051719A1 (en) * 1999-07-21 2005-03-10 Sionex Corporation Systems for differential ion mobility analysis
US7365316B2 (en) 1999-07-21 2008-04-29 The Charles Stark Draper Laboratory Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry
US20080128609A1 (en) * 1999-07-21 2008-06-05 Sionex Corporation Systems for differential ion mobility analysis
US20050133716A1 (en) * 1999-07-21 2005-06-23 Miller Raanan A. Explosives detection using differential ion mobility spectrometry
US7619214B2 (en) 1999-07-21 2009-11-17 The Charles Stark Draper Laboratory, Inc. Spectrometer chip assembly
US20050145789A1 (en) * 1999-07-21 2005-07-07 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray augmented high field asymmetric ion mobility spectrometry
US7605367B2 (en) 1999-07-21 2009-10-20 Sionex Corporation Explosives detection using differential mobility spectrometry
US7576319B2 (en) 1999-07-21 2009-08-18 Sionex Corporation Systems for differential ion mobility analysis
US7547879B2 (en) 1999-07-21 2009-06-16 The Charles Stark Draper Laboratory, Inc. Longitudinal field driven ion mobility filter and detection system
US7211791B2 (en) 1999-07-21 2007-05-01 The Charles Stark Draper Laboratory, Inc. Method and apparatus for chromatography-high field asymmetric waveform ion mobility spectrometry
US7462825B2 (en) 1999-07-21 2008-12-09 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray-augmented high field asymmetric ion mobility spectrometry
US20050263699A1 (en) * 1999-07-21 2005-12-01 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray augmented high field asymmetric ion mobility spectrometry
US6972407B2 (en) 1999-07-21 2005-12-06 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray augmented high field asymmetric ion mobility spectrometry
US7456390B2 (en) 1999-07-21 2008-11-25 The Charles Stark Draper Laboratory, Inc. Longitudinal field driven ion mobility filter and detection system
US20070084999A1 (en) * 1999-07-21 2007-04-19 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray-augmented high field asymmetric ion mobility spectrometry
US7030372B2 (en) 1999-07-21 2006-04-18 Sionex Corporation Micromachined field asymmetric ion mobility filter and detection system
US6495823B1 (en) 1999-07-21 2002-12-17 The Charles Stark Draper Laboratory, Inc. Micromachined field asymmetric ion mobility filter and detection system
US7057168B2 (en) 1999-07-21 2006-06-06 Sionex Corporation Systems for differential ion mobility analysis
US7075068B2 (en) 1999-07-21 2006-07-11 The Charles Stark Draper Laboratory, Inc. Method and apparatus for electrospray augmented high field asymmetric ion mobility spectrometry
US20060151687A1 (en) * 1999-07-21 2006-07-13 Sionex Corporation Systems for differential ion mobility analysis
US20080128612A1 (en) * 1999-07-21 2008-06-05 The Charles Stark Draper Laboratory, Inc. Method and apparatus for chromatography high field asymmetric waveform ion mobility spectrometry
US7148477B2 (en) 1999-07-21 2006-12-12 Sionex Corporation System for trajectory-based ion species identification
US7129482B2 (en) 1999-07-21 2006-10-31 Sionex Corporation Explosives detection using differential ion mobility spectrometry
US20080135745A1 (en) * 1999-07-21 2008-06-12 Sionex Corporation Explosives detection using differential mobility spectrometry
US7098449B1 (en) 1999-07-21 2006-08-29 The Charles Stark Draper Laboratory, Inc. Spectrometer chip assembly
US20060192102A1 (en) * 1999-07-21 2006-08-31 The Charles Stark Draper Laboratory, Inc. Longitudinal field driven ion mobility filter and detection system
US20080185512A1 (en) * 1999-07-21 2008-08-07 Sionex Corporation Method and apparatus for enhanced ion mobility based sample analysis using various analyzer configurations
US7399958B2 (en) 1999-07-21 2008-07-15 Sionex Corporation Method and apparatus for enhanced ion mobility based sample analysis using various analyzer configurations
US20030146759A1 (en) * 2000-04-27 2003-08-07 Vladimir Bashkirov Nanodosimeter based on single ion detection
US6787771B2 (en) * 2000-04-27 2004-09-07 Loma Linda University Nanodosimeter based on single ion detection
US7081619B2 (en) 2000-04-27 2006-07-25 Loma Linda University Nanodosimeter based on single ion detection
US20050109929A1 (en) * 2000-04-27 2005-05-26 Vladimir Bashkirov Nanodosimeter based on single ion detection
US20020134933A1 (en) * 2001-03-20 2002-09-26 Ion Track Instruments Llc Enhancements to ion mobility spectrometers
US6765198B2 (en) * 2001-03-20 2004-07-20 General Electric Company Enhancements to ion mobility spectrometers
US7714284B2 (en) 2001-06-30 2010-05-11 Sionex Corporation Methods and apparatus for enhanced sample identification based on combined analytical techniques
US7045776B2 (en) 2001-06-30 2006-05-16 Sionex Corporation System for collection of data and identification of unknown ion species in an electric field
US20030052263A1 (en) * 2001-06-30 2003-03-20 Sionex Corporation System for collection of data and identification of unknown ion species in an electric field
US7119328B2 (en) 2001-06-30 2006-10-10 Sionex Corporation System for DMS peak resolution
US20050040330A1 (en) * 2001-06-30 2005-02-24 Kaufman Lawrence A. System for DMS peak resolution
US7279680B2 (en) 2001-08-08 2007-10-09 Sionex Corporation Method and apparatus for plasma generation
US20030070913A1 (en) * 2001-08-08 2003-04-17 Sionex Corporation Capacitive discharge plasma ion source
US20060237669A1 (en) * 2001-08-08 2006-10-26 Sionex Corporation Method and apparatus for plasma generation
US7274015B2 (en) 2001-08-08 2007-09-25 Sionex Corporation Capacitive discharge plasma ion source
US7091481B2 (en) 2001-08-08 2006-08-15 Sionex Corporation Method and apparatus for plasma generation
US7217920B2 (en) 2001-08-14 2007-05-15 Sionex Corporation Pancake spectrometer
US20040232325A1 (en) * 2001-08-14 2004-11-25 Sionex Corporation Pancake spectrometer
US20060169886A1 (en) * 2001-08-14 2006-08-03 Sionex Corporation Pancake spectrometer
US7339164B2 (en) 2002-02-21 2008-03-04 Sionex Corporation Systems and methods for ion mobility control
US7598489B2 (en) 2002-02-21 2009-10-06 Sionex Corporation Systems and methods for ion mobility control
US7122794B1 (en) 2002-02-21 2006-10-17 Sionex Corporation Systems and methods for ion mobility control
US20040094704A1 (en) * 2002-04-12 2004-05-20 Sionex Corporation Method and apparatus for control of mobility-based ion species identification
US7230238B2 (en) 2002-04-12 2007-06-12 Sionex Corporation Method and apparatus for control of mobility-based ion species identification
US20050156107A1 (en) * 2002-04-12 2005-07-21 Miller Raanan A. Method and apparatus for control of mobility-based ion species identification
US7005632B2 (en) 2002-04-12 2006-02-28 Sionex Corporation Method and apparatus for control of mobility-based ion species identification
US7019291B2 (en) 2002-10-12 2006-03-28 Sionex Corporation NOx monitor using differential mobility spectrometry
US20050092914A1 (en) * 2002-10-12 2005-05-05 Sionex Corporation NOx monitor using differential mobility spectrometry
US7227136B2 (en) 2003-03-07 2007-06-05 Airsense Analytics Gmbh Method and arrangement for detecting harmful substances
US20060219892A1 (en) * 2003-03-07 2006-10-05 Andreas Walte Method and arrangement for detecting harmful substances
US7227134B2 (en) 2003-11-25 2007-06-05 Sionex Corporation Mobility based apparatus and methods using dispersion characteristics, sample fragmentation, and/or pressure control to improve analysis of a sample
US20050139762A1 (en) * 2003-11-25 2005-06-30 Sionex Corporation Mobility based apparatus and methods using dispersion characteristics, sample fragmentation, and/or pressure control to improve analysis of a sample
US20070252082A1 (en) * 2003-11-25 2007-11-01 Sionex Corporation Mobility based apparatus and methods using dispersion characteristics, sample fragmentation, and/or pressure control to improve analysis of a sample
US7902498B2 (en) 2003-12-18 2011-03-08 Dh Technologies Development Pte. Ltd. Methods and apparatus for enhanced ion based sample detection using selective pre-separation and amplification
US20110042561A1 (en) * 2003-12-18 2011-02-24 Dh Technologies Development Pte. Ltd. Methods and apparatus for enhanced ion based sample detection using selective pre-separation and amplificaton
US8592751B2 (en) 2003-12-18 2013-11-26 Dh Technologies Development Pte. Ltd. Methods and apparatus for enhanced ion based sample detection using selective pre-separation and amplification
US20050167583A1 (en) * 2003-12-18 2005-08-04 Sionex Corporation Methods and apparatus for enhanced ion based sample detection using selective pre-separation and amplification
US7456394B2 (en) 2004-02-02 2008-11-25 Sionex Corporation Compact sample analysis systems and related methods of using combined chromatography and mobility spectrometry techniques
US20050230616A1 (en) * 2004-02-02 2005-10-20 Sionex Corporation Compact sample analysis systems and related methods of using combined chromatography and mobility spectrometry techniques
US20050253061A1 (en) * 2004-04-28 2005-11-17 Sionex Corporation Systems and methods for ion species analysis with enhanced condition control and data interpretation
US7381944B2 (en) 2004-04-28 2008-06-03 Sionex Corporation Systems and methods for ion species analysis with enhanced condition control and data interpretation
US9048073B2 (en) 2004-11-04 2015-06-02 Micromass Uk Limited Mass spectrometer
US10724990B2 (en) 2004-11-04 2020-07-28 Micromass Uk Limited Mass spectrometer
US9410927B2 (en) 2004-11-04 2016-08-09 Micromass Uk Limited Mass spectrometer
US8735805B2 (en) 2004-11-04 2014-05-27 Micromass Uk Limited Mass spectrometer
US7399959B2 (en) 2004-12-03 2008-07-15 Sionex Corporation Method and apparatus for enhanced ion based sample filtering and detection
US20060222562A1 (en) * 2004-12-03 2006-10-05 Sionex Corporation Method and apparatus for enhanced ion based sample filtering and detection
US7812309B2 (en) * 2005-02-09 2010-10-12 Thermo Finnigan Llc Apparatus and method for an electro-acoustic ion transmittor
US20090127457A1 (en) * 2005-02-09 2009-05-21 Roger Guevremont Apparatus and method for an electro-acoustic ion transmittor
US7608818B2 (en) 2005-04-29 2009-10-27 Sionex Corporation Compact gas chromatography and ion mobility based sample analysis systems, methods, and devices
US20070029477A1 (en) * 2005-04-29 2007-02-08 Sionex Corporation Compact gas chromatography and ion mobility based sample analysis systems, methods, and devices
US7579589B2 (en) 2005-07-26 2009-08-25 Sionex Corporation Ultra compact ion mobility based analyzer apparatus, method, and system
US7541575B2 (en) 2006-01-11 2009-06-02 Mds Inc. Fragmenting ions in mass spectrometry
US20070158546A1 (en) * 2006-01-11 2007-07-12 Lock Christopher M Fragmenting ions in mass spectrometry
US20070272852A1 (en) * 2006-01-26 2007-11-29 Sionex Corporation Differential mobility spectrometer analyzer and pre-filter apparatus, methods, and systems
US20090032695A1 (en) * 2006-06-09 2009-02-05 Kaye William J Miniaturized Ion Mobility Spectrometer
US8963082B2 (en) 2006-06-09 2015-02-24 Rapiscan Systems, Inc. Miniaturized ion mobility spectrometer
US9646811B2 (en) 2006-06-09 2017-05-09 Rapiscan Systems, Inc. Miniaturized ion mobility spectrometer
US7550717B1 (en) 2006-11-30 2009-06-23 Thermo Finnigan Llc Quadrupole FAIMS apparatus
US8217344B2 (en) 2007-02-01 2012-07-10 Dh Technologies Development Pte. Ltd. Differential mobility spectrometer pre-filter assembly for a mass spectrometer
US20090114811A1 (en) * 2007-11-06 2009-05-07 Jurgen Landgraf Ion mobility spectrometer and method for operation
US20090114812A1 (en) * 2007-11-06 2009-05-07 Jurgen Landgraf Ion mobility spectrometer with substance collector
US7902501B2 (en) * 2007-11-06 2011-03-08 Bruker Daltonik Gmbh Ion mobility spectrometer and method for operation
US7884320B2 (en) * 2007-11-06 2011-02-08 Brucker Daltonik Gmbh Ion mobility spectrometer with substance collector
DE102008005281A1 (en) 2008-01-19 2009-07-30 Airsense Analytics Gmbh Method and device for the detection and identification of gases
US9404889B2 (en) 2008-01-19 2016-08-02 Airsense Analytics Gmbh Method and device for detection and identification of gases
US20100314548A1 (en) * 2008-01-19 2010-12-16 Airsense Analytics Gmbh Method and device for detection and identification of gases
US20110015875A1 (en) * 2008-03-10 2011-01-20 Airsense Analytics Gmbh Method and device for the detection and identification of gases in airplane interior spaces
WO2009112001A1 (en) 2008-03-10 2009-09-17 Airsense Analytics Gmbh Method and device for the detection and identification of gases in airplane interior spaces
US9020764B2 (en) 2008-03-10 2015-04-28 Airsense Analytics Gmbh Method and device for the detection and identification of gases in airplane interior spaces
US9084887B2 (en) 2009-02-05 2015-07-21 Loma Linda University Medical Center Proton scattering analysis system
US9878180B2 (en) 2009-02-05 2018-01-30 Loma Linda University Medical Center Proton scattering analysis system
US9213107B2 (en) 2009-10-01 2015-12-15 Loma Linda University Medical Center Ion induced impact ionization detector and uses thereof
US9207193B2 (en) 2010-02-12 2015-12-08 Loma Linda University Medical Center Systems and methodologies for proton computed tomography
US20110220794A1 (en) * 2010-02-12 2011-09-15 Yair Censor Systems and methodologies for proton computed tomography
US10180505B2 (en) 2010-02-12 2019-01-15 Loma Linda University Medical Center Systems and methodologies for proton computed tomography
US8742363B2 (en) 2010-09-09 2014-06-03 Airsense Analytics Gmbh Method and apparatus for ionizing gases using UV radiation and electrons and identifying said gases
EP2428796A1 (en) 2010-09-09 2012-03-14 Airsense Analytics GmbH Method and device for identifying and ionising gases by means of UV-radiation and electrons
WO2012031850A1 (en) 2010-09-09 2012-03-15 Airsense Analytics Gmbh Method and apparatus for ionizing gases using uv radiation and electrons and identifying said gases
EP2428797A1 (en) 2010-09-14 2012-03-14 Airsense Analytics GmbH Method and device for identifying and detecting gases by means of ion mobility spectrometry
WO2012034795A1 (en) 2010-09-14 2012-03-22 Airsense Analytics Gmbh Method and apparatus for detecting and identifying gases by means of ion mobility spectrometry
US9880301B2 (en) 2011-03-07 2018-01-30 Loma Linda University Medical Center Systems, devices and methods related to calibration of a proton computed tomography scanner
US8841602B2 (en) 2011-03-07 2014-09-23 Loma Linda University Medical Center Systems, devices and methods related to calibration of a proton computed tomography scanner
US9274067B2 (en) 2011-03-07 2016-03-01 Loma Linda University Medical Center Systems, devices and methods related to calibration of a proton computed tomography scanner
US9753012B2 (en) 2015-06-19 2017-09-05 Airsense Analytics Gmbh Method and device for the identification of gases
EP3106867A1 (en) 2015-06-19 2016-12-21 Airsense Analytics GmbH Method and device for identifying gases
EP3457125A1 (en) 2017-09-14 2019-03-20 Airsense Analytics GmbH Device and method for detecting hazardous gases
US11658020B2 (en) 2020-11-24 2023-05-23 Inficon, Inc. Ion source assembly with multiple ionization volumes for use in a mass spectrometer

Similar Documents

Publication Publication Date Title
US3621240A (en) Apparatus and methods for detecting and identifying trace gases
US3639757A (en) Apparatus and methods employing ion-molecule reactions in batch analysis of volatile materials
US4445038A (en) Apparatus for simultaneous detection of positive and negative ions in ion mobility spectrometry
de Heer et al. Large ion volume time‐of‐flight mass spectrometer with position‐and velocity‐sensitive detection capabilities for cluster beams
Breskin Progress in low-pressure gaseous detectors
Danilatos Theory of the gaseous detector device in the environmental scanning electron microscope
Goodrich et al. Resistance strip magnetic electron multiplier
EP0103586B1 (en) Sputter initiated resonance ionization spectrometry
US5206508A (en) Tandem mass spectrometry systems based on time-of-flight analyzer
JP3176918B2 (en) Trace component analyzer and method
US5659170A (en) Ion source for compact mass spectrometer and method of mass analyzing a sample
US5770857A (en) Apparatus and method of determining molecular weight of large molecules
Dietz Basic properties of electron multiplier ion detection and pulse counting methods in mass spectrometry
Eubank et al. Ion energy analyzer for plasma measurements
US3742213A (en) Apparatus and methods for detecting, separating, concentrating and measuring electronegative trace vapors
US5206594A (en) Apparatus and process for improved photoionization and detection
US3626180A (en) Apparatus and methods for separating, detecting, and measuring trace gases with enhanced resolution
US3697748A (en) Plasma chromatograph with internally heated inlet system
JP3500323B2 (en) Ionizer used for cycloid mass spectrometer
US3621239A (en) Detecting a trace substance in a sample gas comprising reacting the sample with different species of reactant ions
Eisele Direct tropospheric ion sampling and mass identification
US5545894A (en) Compact hydrogen/helium isotope mass spectrometer
JPH05251039A (en) Secondary ion mass spectrometry device
US2612607A (en) Mass spectrometer
US3626178A (en) Gas or liquid chromatograph with detector employing ion-molecule reactions and ion drift

Legal Events

Date Code Title Description
AS Assignment

Owner name: GIBSON HENRY C,JR. TRUSTEE FOR THE STOCKHOLDERS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:FRANKLIN GNO CORPORATION A FL CORP.;REEL/FRAME:004326/0409

Effective date: 19761227

AS Assignment

Owner name: PCP, INC., 2155 INDIAN ROAD, W. PALM BEACH, FLORID

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:GIBSON HENRY C, JR. TRUSTEE FOR THE STOCKHOLDERS OF FRANKLIN GNO CORP.;REEL/FRAME:004485/0773

Effective date: 19851122