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Publication numberUS3886365 A
Publication typeGrant
Publication dateMay 27, 1975
Filing dateAug 27, 1973
Priority dateAug 27, 1973
Also published asCA1008976A1, DE2439711A1, DE2439711B2
Publication numberUS 3886365 A, US 3886365A, US-A-3886365, US3886365 A, US3886365A
InventorsKruger William P, Michnowicz John A
Original AssigneeHewlett Packard Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Multiconfiguration ionization source
US 3886365 A
Abstract
This is an ion-producing source having a distinct chemical ionization configuration and a distinct electron impact configuration. In this source, a hollow chamber including an ion source and a source of sample molecules receives a hollow, slidable cylindrical member having a chemical ionization chamber within it. Orifices in the chamber and the cylindrical member connect the chemical ionization source chamber to the electron source and to the sample molecule source when the cylindrical member is pulled to one position. When the cylindrical member is pulled to another position, the slidable cylindrical member and the inside walls of the chamber define the ionization region to which the electron source and the sample molecule source are directly connected. By moving the cylindrical member, the ionization source can be changed from a chemical ionization source to an electron impact source.
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United States Patent Kruger et al.

May 27, 1975 MULTICONFIGURATION IONIZATION Primary ExaminerJames W. Lawrence SOURCE Assistant Examiner-B. C. Anderson [75] Inventors: William P. Kruger, Los Altos Hills; Attorney Agent or Flrmpamck Barren John A. Michnowicz, Santa Clara, both of Calif. ABSTRACT [73] Assignee: newletbpackard Company, Palo This is an ion-producing source having a distinct Alto Calm chemical ionization configuration and a distinct electron impact configuration. In this source, a hollow i 1 Flledi g- 9 1973 chamber including an ion source and a source of sam- [21] APPL No: 391,721 ple molecules receives a hollow, slidable cylindrical member having a chemical ionization chamber within it. Orifices in the chamber and the cylindrical member I Cl 250/423; 250/427 connect the chemical ionization source chamber to [51 1 Int. Cl. the electron sgurce and to the sample molecule ource Field of Search 250/424, 423, 427 when the cylindrical member is pulled to one position.

When the cylindrical member is pulled to another pol Referemes Cied sition, the slidable cylindrical member and the inside UNITED STATES PATENTS walls of the chamber define the ionization region to 3.115591 12/1963 Brunnee a. 250/423 WhiCh the electron mum and the Sample molecule 3355.587 11/1967 j k n 25 7 source are directly connected. By moving the cylindri- 3.405.263 /1968 Wanless etalm. 250/285 cal member. the ionization source can be changed 3.553. 1/197! Tieman 250/427 from a chemical ionization source to an electron im- MLlIlSOI'l pact ource 3.582.645 6/197l Brunnee et al. n i 250/423 10 Claims, 2 Drawing Figures 5 46 l2 I6 44 ii t I I I I 48 55 flfi 4 34 Emma/232 I H% I/lII/I/I/ III/If J I 73 S 38 24 {t ngo 72 O 36 [17/ l\\\\\\\ PATH-1TH m 2 7 ms igure 1 igure 2 1 MULTICONFIGURATION IONIZATION SOURCE BACKGROUND OF THE INVENTION Ion sources are employed with mass spectrometers in the analysis of substances. Commonly used sources are the electron impact source and the chemical ionization source. The first one has a large electron entrance, :1 large ion exit. and an ionization region where the incoming electrons fragment as well as ionize vapor molecules thus providing a large quantity of information which does not necessarily give clear indication of the identity of a substance. The chemical ionization source has, on the other hand, a small electron entrance, a small ion exit, and an ionization region where the pres sure can be maintained at such levels that ionmolecule collisions are extremely likely to occur, such collisions leading to ready identification of the molecular weight of a substance.

Operation of a mass spectrometer alternately with electron impact and chemical ionization sources has required many hours of down time during which the operation of the spectrometer stops. An object of this invention is to permit changing between the electron impact and the chemical ionization configurations with minimal interruption of operation of the mass spectrometer.

BRIEF SUMMARY OF THE INVENTION According to the preferred embodiment, this inven tion provides an ionization source with two distinct ion ization chambers, one which operates as an electron impact ionization source and the other as a chemical ionization source. The invention may be used with a mass spectrometer and changes in configuration can be made easily and quickly. The main elements of the invention include a hollow chamber having a plurality of orifices transverse to the longitudinal axis of the chamber. One of the orifices contains an electron source, and another one is a gaseous sample inlet. A hollow slidable cylindrical member having smaller transverse orifices than those in the hollow chamber fits inside the hollow chamber. At one of its ends, the cylindrical member has two electrode inserts separated from each other along the longitudinal axis and defining a first ionization region between them and the inside walls of the hollow cylindrical member, This region is connected to the sample inlet orifice and to the electron source orifice when the hollow cylinder is in a first position. A second ionization region is defined by the inside walls of the hollow chamber, the outer electrode insert of the cylindrical member, and the open end of the hollow chamber, when the cylindrical member is in a second position. This second region is directly connected to the electron source orifice and to the sample inlet. In this manner, when the cylindrical member is in the first position. the source operates as a chemical ionization source and when the cylindrical member is in the second position, the source operates as an electron impact source. The position of the cylindrical member can be changed quickly and easily by simply pushing or pulling a handle attached to the cylinder.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross-sectional view of the preferred embodiment of the present invention in the chemical ionization configuration.

FIG. 2 shows the apparatus of FIG. I in the electron impact configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. I and 2 show a vacuum envelope I4 which is connected to an ordinary vacuum pump through a port 9 for evacuating air from the envelope. An ion chamber I6, which may be a stainless steel tube. is supported within envelope I4 by a support member I2 and has orifices, l7, I7 and 23 transverse to its longitudinal axis. Orifice [7 contains a filament 18 near the periphery of ion chamber 16 and near an end 19 of ion chamber I6. Orifice 23 is an inlet for samples to be ionized. The ion chamber 16 has a preferably cylindrical bore 24 along the longitudinal axis. Filament orifice I7 intersects bore 24 near end 19.

A hollow member 28 fits slidably inside bore 24, which member may be made of stainless steel tubingv Electrode inserts 35 and 36 are supported by and fastened to the inside of slide member 28 by insulators preferably made of ceramic. Insert 35 is located at end 21 of member 28 and has a passage 34 through it. Insert 36 is spaced apart fom insert 35 and has a passage 39 through it. A connector 38 passes through passage 39 and engages passage 34 in insert 35 when member 28 has been moved to the left as shown in FIG. 2. A spring 40 attaches connector 38 to a base block 42, and this block is in turn affixed to but electrically insulated from chamber 16. Slide member 28 has a slot 44 through which base block 42 passes. The external surface of hollow member 28 is preferably hardened to prevent galling or binding with chamber 16. A handle 48 attaches to end 53 of hollow member 28 and is used to displace this member from the first position to the second position as shown in FIGS. 1 and 2 respectively. A bellows 46 surrounds handle 48 and connects the end 53 of hollow member 28 with a wall 55 of vacuum envelope 14. A support member 12 surrounds the bellows 46 and affixes the chamber 16 to wall 55. A pivot axle between a support member 71 and an arm 72 permits pulling or pushing arm 72, which is connected to handle 48, for placing cylinder 28 in either the chemical ionization configuration as shown in FIG. I or the electron impact configuration as shown in FIG. 2. Arm 72 is connected to handle 48 by a Vernier screw arrangement 73 for making fine alignment adjustments of electron passage 32 with filament orifice 17.

As shown in FIG, I, electrode inserts 35 and 36 and the inner periphery of hollow member 28 define a first ionization region 30 when hollow member 28 is to the right, as in FIG. 1. A second ionization region 30' is defined by the interior walls of chamber body 16, the electrode insert 35 to the left, and the open end I9 of chamber 16 to the right. A passage 32 through the wall of hollow member 28 permits entry of electrons into the ionization region 30 from orifice 17 when hollow member 28 is to the rightv A sample inlet 23 through the walls of ion chamber 16 permits entry of an ionization sample into ionization region 30 when cylinder 28 is to the left as shown in FIG. 2. Sample inlet 23, and sample inlet 20 passing through the walls of hollow member 28, permit entry of an ionization sample into ionization region 30, when hollow member 28 is to the right as shown in FIG. 1. A passage 34 permits exit of ions from the ionization region 30 to an ion lens assembly 26. Both passages 32 and 34 may have a conical configuration to improve entry of the electrons through the first passage and exit ofthe ions through the second passage. Passages 32 and 34, the electron entrance and ion exit passages respectively of the chemical ioniza tion chamber. are much smaller than the respective passages 17 and 2] of the electron impact chamber. The smaller size of passages 32 and 34 permits maintaining a higher pressure in ionization region 30 than in ionization region 30'.

Magnets 52 and 52' are located adjacent to filament l8 and to an electron collector 50, respectively. which is disposed on the periphery of chamber [6 diametrically opposed to filament 18. The magnets direct an electron beam from the filament to the collector. The ion lens assembly 26, adjacent to end 19, extends away from chamber 16 and. when the appropriate potentials are applied, focuses ions emerging from ionization re gions 30 and 30 into a mass filter for analysis (not shown).

A potential source 70 is connected to insert 35 by connector 38 to maintain insert 35 at a potential for re pelling ions when the hollow member 28 is to the left. as shown in FlG. 2. When the hollow member 28 is to the right. connector 38 engages only insert 36 to maintain a repelling potential on this insert. which insert b now becomes a repeller electrode.

When the hollow cylindrical member is to the left the ionization source is operating in the electron im pact configuration where the pressure inside ionization region 30' is about l Torr; the ionization electrons have energies of about 70 eV; and mean-free-paths of about 2 X l0 inches. The electrons in this configuration fragment the sample molecules and produce many ions whose mass'to-charge ratios do not necessarily correspond to the molecular weight of the sample. When the hollow cylindrical member is to the right, the ionization source is operating in the chemical ioniza tion configuration where the pressure in ionization re gion 30 is up to 1.0 Torr; the ionization electrons have energies of about 100 to 500 eV; and short mean-freepaths of about 2 X inches. The electrons in this configuration do not fragment the sample molecules as much as in the electron impact configuration. but produce an abundance of ions whose mass-tocharge ratio corresponds more accurately to the molecular weight of the sample.

We claim:

I. A multiconfiguration. multimode ionization source comprising:

a vacuum tight envelope;

a chamber having walls surrounding an internal cavity and mounted within the envelope. said chamber having a plurality of openings;

an electron source disposed exterior to the chamber for supplying electrons to the chamber through a first of said openings;

sample inlet means for supplying a gaseous sample through a second of said openings for reaction with the electrons inside the chamber to create ions. said ions exiting through a third of said openings;

aperture control means for changing the size of the first and third openings for changing the pressure ofthe sample in the chamber. thereby changing the operating mode of the source from a first to a sec ond ionization mode; and

ion repelling means disposed inside the chamber for repeliing ions out of the chamber through the third opening.

2. A muiticonfiguration ionization source as in claim I wherein:

the aperture control means comprises a movable member within the chamber. said member having an electron opening smaller than said first opening and also having an ion opening smaller than said third opening:

said electrons from the source pass through the electron opening and the first opening when said movable member is in a first position;

said ions in the cavity pass through the ion opening and the third opening when the movable member is in the first position; and

said electrons pass through only the first opening and said ions pass through only the third opening when the movable member is in a second position.

3. A multiconfiguration ionization source as in claim 2 wherein the movable member comprises a hollow slidable cylinder having an ion exit end and a handie end.

4. A multiconfiguration ionization source as in claim 3 including:

a bellows having a first end attached to the handle end of the cylinder and by a second end to a wall of the vacuum tight envelope; and

a handle surrounded by the bellows, one end of said handle attaches to the cylinder while the other end of the the handle protrudes through said vacuum tight envelope wall.

5. A multiconfiguration ionization source as in claim 4 wherein there is an electron collector opposite the electron source. and wherein there are magnets disposed adjacent the electron source and the electron collector to direct the electrons from the electron source.

6. A multiconfiguration ionization source as in claim 5 wherein an ion lens assembly is attached to the electron source end of the chamber for focusing ions into a utilization device.

7. A multiconfiguration ionization source as in claim 6 wherein a vernier adjustment screw is attached to said handle for making fine adjustments in the position of the cylinder for aligning the electron opening with the electron source.

8. A multiconfiguration ionization source as in claim 3 wherein the ion repelling means comprises:

a first and second repeller electrode mounted in and electrically insulated from the hollow slidable cylinder'. and

a connector connectable to a source of potential for making an electrical connection with the first repeller electrode when the slidable cylinder is in the first position and with the second repeller electrode when the slidable cylinder is in the second position.

9. A multiconfiguration ionization source as in claim 8 wherein said ion opening is in the second repeller electrode.

[0. A multiconfiguration ionization source as in claim 1 wherein the first ionization mode is a chemical ionization mode and the second ionization mode is an electron impact ionization mode.

t t t

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3115591 *May 27, 1960Dec 24, 1963Atlas Werke AgIon source for mass spectrometer
US3355587 *Mar 3, 1966Nov 28, 1967Ludolf JenckelGas analysis apparatus comprising plural ionization chambers with different ionizing electron beam energy levels in the chambers
US3405263 *Jan 14, 1966Oct 8, 1968Exxon Research Engineering CoDual mass spectrometer ion source comprising field ionization and electron bombardment sources and the method of use
US3553452 *Feb 17, 1969Jan 5, 1971Us Air ForceTime-of-flight mass spectrometer operative at elevated ion source pressures
US3555272 *Mar 14, 1968Jan 12, 1971Exxon Research Engineering CoProcess for chemical ionization for intended use in mass spectrometry and the like
US3582645 *Nov 7, 1967Jun 1, 1971Varian Mat GmbhCombined field and impact ionization source for mass spectrometers
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3992632 *Apr 16, 1975Nov 16, 1976Hewlett-Packard CompanyMulticonfiguration ionization source
US4037108 *Mar 9, 1976Jul 19, 1977Helmut JordanIon source with capability of changing between operation modes
US4105916 *Feb 28, 1977Aug 8, 1978Extranuclear Laboratories, Inc.Methods and apparatus for simultaneously producing and electronically separating the chemical ionization mass spectrum and the electron impact ionization mass spectrum of the same sample material
US4377745 *Apr 27, 1981Mar 22, 1983Cherng ChangMass spectrometer for chemical ionization, electron impact ionization and mass spectrometry/mass spectrometry operation
US4388531 *Mar 6, 1981Jun 14, 1983Finnigan CorporationIonizer having interchangeable ionization chamber
US4447728 *Feb 5, 1982May 8, 1984Finnigan CorporationIonizer including discharge ion source and method
US5302827 *May 11, 1993Apr 12, 1994Mks Instruments, Inc.Quadrupole mass spectrometer
US5331158 *Dec 7, 1992Jul 19, 1994Hewlett-Packard CompanyMethod and arrangement for time of flight spectrometry
US6646257Sep 18, 2002Nov 11, 2003Agilent Technologies, Inc.Multimode ionization source
US7078681Aug 13, 2003Jul 18, 2006Agilent Technologies, Inc.Multimode ionization source
US7091483Feb 25, 2005Aug 15, 2006Agilent Technologies, Inc.Apparatus and method for sensor control and feedback
US7488953May 31, 2006Feb 10, 2009Agilent Technologies, Inc.Multimode ionization source
US7791042Nov 17, 2006Sep 7, 2010Thermo Finnigan LlcMethod and apparatus for selectively performing chemical ionization or electron ionization
USRE35701 *Mar 29, 1996Dec 30, 1997Mks Instruments, Inc.Quadrupole mass spectrometer
EP0060075A2 *Mar 2, 1982Sep 15, 1982Finnigan CorporationIonizer having interchangeable ionization chamber
EP1507282A2 *Feb 10, 2004Feb 16, 2005Agilent Technologies Inc., A Delaware CorporationMultimode ionization source
Classifications
U.S. Classification250/423.00R, 250/427
International ClassificationH01J49/10, G01N27/62, H01J49/14
Cooperative ClassificationH01J49/145, H01J49/147
European ClassificationH01J49/14E, H01J49/14B