US3685911A - Capillary arc plasma source for and method of spectrochemical analysis - Google Patents

Capillary arc plasma source for and method of spectrochemical analysis Download PDF

Info

Publication number
US3685911A
US3685911A US737633A US3685911DA US3685911A US 3685911 A US3685911 A US 3685911A US 737633 A US737633 A US 737633A US 3685911D A US3685911D A US 3685911DA US 3685911 A US3685911 A US 3685911A
Authority
US
United States
Prior art keywords
tube
passageway
arc
anode
cathode
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
US737633A
Other languages
English (en)
Inventor
Ralph L Dahlquist
James L Jones
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.)
APPLIED RES LAB
APPLIED RESEARCH LAB Inc
EIDP Inc
Original Assignee
APPLIED RES LAB
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 APPLIED RES LAB filed Critical APPLIED RES LAB
Application granted granted Critical
Publication of US3685911A publication Critical patent/US3685911A/en
Assigned to JAMES TALCOTT, INC., LLOYDS BANK INTERNATIONAL LIMITED reassignment JAMES TALCOTT, INC. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: APPLIED RESEARCH LABORATORIES, INC., ARL APPLIED RESEARCH LABORATORIES, S.A.
Assigned to E.I. DU PONT DE NEMOURS AND COMPANY reassignment E.I. DU PONT DE NEMOURS AND COMPANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: BUCKFELDER, JOHN J., SCHLEINITZ, HENRY M.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/66—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
    • G01N21/67—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence using electric arcs or discharges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/73—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using plasma burners or torches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes

Definitions

  • Spectrochemical analysis by optical emission and by atomic absorption are well known and widely used techniques. Generally in these techniques, a material to be analyzed is heated to a relatively high temperature to evaporate, dissociate and excite the atoms of the material..ln optical emission analysis, light emitted by the material is analyzed; in atomic absorption analysis, light from a separate source is directed through the excited material, and the attenuation is measured.
  • one important object of the invention is to provide means for exciting a material for analysis by optical emission or atomic absorption, which avoids or overcomes many of the limitations and difficulties of the prior art arrangements, is of simple and inexpensive construction, easy to use, and reliable and long lived in service.
  • the invention contemplates the use of an electric arc plasma for exciting a material to be analyzed.
  • The are is wall-stabilized within a capillary tube, and is sustained by a working gas flowing through the tube.
  • the material to be analyzed, in gaseous or nebulized form, is carried through the are by the working gas. Because of the wall-stabilized effect, the arc operates at a very high power density, and is highly stable in position and shape.
  • the direction of observation is preferably along the length of the arc to insure optimum signal detection regardless of the location in the are where the signals originate or occur at strength.
  • Self-absorption effects are small as compared to other, prior arrangements.
  • the device is capable of operating continuously, quietly and inexpensively for long periods of time, is convenient and easy to use, rugged and long lasting in service, and is advantageous in many other respects, as will become apparent hereinafter.
  • FIG. 1 is a cross-sectional view, partly in schematic form, of an electric arc plasma source according to a first embodiment of the invention.
  • FIG. 2 is a cross-sectional view, partly in schematic form, of an electric arc plasma source according to another embodiment of the invention, as arranged to accommodate analysis by atomic absorption.
  • a plasma source according to the first embodiment as shown in FIG. 1 is arranged for analysis by optical emission. It includes a generally cylindrical vessel 10 having a small opening 12 at one end, a window 14 at the end opposite from the opening 12, a gas inlet port 16 extending through the side wall of the vessel near the window 14, and a cooling arrangement such as the annular passage 18 for circulating a liquid to cool the wall of the opening 12.
  • the material around the opening 12 is electrically and thermally conductive. It serves as the anode for the arc.
  • the bore 22 constitutes the introduction chamber for the material to be analyzed.
  • a feed tube 24 extends laterally from the chamber 22 to the exterior of the plate 20.
  • the capillary tube 26 is formed in a thermally conductive, dynamically cooled, cap-like body 28 fitted to the plate 20 on the opposite side of the plate from the vessel 10.
  • the tube 26, the introduction chamber 22, and the anode 12 are all coaxially aligned.
  • capillary as used in this application is not intended to be limited to the connotation of hair-like thinness, as in other arts, but to include tubes of substantially larger dimensions such as of one-eighth or even one-quarter inch diameter, depending on the atmospheric pressure in the arc.
  • the term capillary is intended to denote that the tube is of small enough diameter to keep the arc wall-stabilized.
  • the wall of the tube cools the outer portion of the gas flowing through it so that the outer portion of the gas is not heated enough to make it electrically conductive. Only a small part of the gas along the central axis of the tube carries the'discharge.
  • the heat losses to the wall of the tube are high, and the arc must be operated at a very high power density to sustain it. Because of this effect, the position and shape of the are are stable, and signals of high intensity are produced.
  • a cathode 30 of electron emissive material which may be, for example, a wire of 99 percent tungsten/l percent thorium alloy, is mounted on an insulating support 32 in a bore 34 extending laterally from the tube 26 at the end opposite from the plate 20.
  • the tip of the cathode 30 is recessed from the tube 26.
  • An exhaust port 36 vents the bore 34 and the tube 26 to atmosphere.
  • a working gas such as argon, typically at normal atmospheric pressure, is introduced both through the port 16 adjacent to the window 14 and through the feed tube 24. Air is rapidly flushed from the interior of the device, and the atmosphere within it is soon constituted practically entirely of the working gas. The are is initiated. This may be done by the application of a momentary high voltage spark.
  • the body member 3 is of an electrically conductive material, the arc first strikes from the anode 12 to the nearest point in the tube 26, and from the cathode 30 to the point nearest to it of the body member 28. The arc persists in this condition for a short period of time, during which the tip of the cathode 30 becomes heated.
  • the arc transfers to a free condition between the anode 12 and the cathodes 30, and becomes wall-stabilized. This will occur automatically under most conditions if the tube 26 is not long, but if it does not, the transfer may be facilitated by briefly increasing the flow of working gas, as may be necessary in most cases when the tube 26 is longer than about one inch.
  • the device operates at substantially atmospheric pressure, and requires only relatively small amounts of working gas, typically about 3 to 5 cubic feet per hour.
  • the capillary tube 26 is about one-eighth inch in diameter and three-quarters inch long.
  • the introduction chamber is about one-quarter inch in diameter and five-sixteenths inch long.
  • the anode opening 12 is about one-eighth inch in length and in diameter.
  • the window 14 is about 1% inch in diameter presently believed that some spacing will be found desirable in almost all cases because fine particles of solids if present in the plasma will tend to diffuse upstream against the gas flow.
  • the diameter of the win- -dow 14 is selected in view of the optical input to the spectrometer to be used for viewing the arc. It is preferably fairly large to maximize the acceptance angle, and, thereby, the amount of light from the are that is fed to the spectrometer.
  • the cathode 30 is preferably recessed from the tube 26 to minimize the effects of light emitted by it.
  • the source is modified as illustrated inFlG. 2 by the addition of an auxiliary cylindrical vessel 40 opening from the end of the tube 26' opposite from the anode 12.
  • a window 42 at the end of the auxiliary vessel 40 enables the passage of light or other radiation from any. selected source (not shown) into the tube 26 from the cathodic end.
  • a port 44 is provided in the side wall of the auxiliary vessel for admitting working gas.
  • the arc may be viewed from either end.
  • significant amounts of radiations from the cathode 30 may be observed, and may at times interfere with the analysis. For this reason, it is presently preferred to make all spectrometric measurements from the anodic end.
  • the light source used for analysis by atomic absorption may be mounted within the auxiliary vessel 40, if
  • the window 42 in the, form of a lens to concentrate the light upon the capilla-.
  • the device of the invention successfully overcomes most of the disadvantages and limitations of the prior art arrangements. Interfering spectra, either continuous or discrete, are limited to those produced by substances intentionally introduced. By judicious selection of the working gas, interference between radiation produced by it and the radiation it is desired to measure may be eliminated. Consumption of inert gases (the working gas) is less by an order of magnitude compared to plasma devices of the prior art thatoperate at atmospheric pressure. Use in the far ultra violet region is limited only by the type of window material used and the transparency'of the working gas. Ifthe window 14 is of lithium fluoride, for example, radiation may be detected at wavelengths as short as about 1,100 angstroms. The device may be readily coupled directly to a vacuum spectrometer.
  • Power supply requirements are relatively small and inexpensive, especially as compared to induction plasmas of the prior art and devices of the interrupted discharge type. Erosion and the consequent repetitive maintenance of thecathode 30 are almost completely eliminated, and greatly reduced compared to the erosion and maintenance requirements of direct current plasma jetsof the prior art.
  • the tube 26 may be made long enough to provide highly sensitive atomic absorption measurements.
  • operating parameters such as the arc current and the flow of working gas may be optimized independently of and without affecting the process or means by which the material being analyzed is obtained.
  • the material being analyzed need not be electrically conductive, as in the case of conventional arc and spark discharge sources. Any material can be fed into the are provided only that it can be put in the form of a gas or nebulized.
  • aperture 12 or 12' may be partly insulated, or a separate anode (not shown) may be used to localize the anodic end of the arc, thus further to enhance the positional stability of the arc.
  • light as used herein is intended to include not only visible light, but also radiation in adjacent parts of the spectrum such as ultra-violet radiation and such other as is useful in spectrometric analytical work of the optical emission and atomic absorption kinds.
  • a capillary arc plasma device comprising:

Landscapes

  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Plasma & Fusion (AREA)
  • Engineering & Computer Science (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
US737633A 1968-06-17 1968-06-17 Capillary arc plasma source for and method of spectrochemical analysis Expired - Lifetime US3685911A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US73763368A 1968-06-17 1968-06-17

Publications (1)

Publication Number Publication Date
US3685911A true US3685911A (en) 1972-08-22

Family

ID=24964656

Family Applications (1)

Application Number Title Priority Date Filing Date
US737633A Expired - Lifetime US3685911A (en) 1968-06-17 1968-06-17 Capillary arc plasma source for and method of spectrochemical analysis

Country Status (5)

Country Link
US (1) US3685911A (OSRAM)
JP (1) JPS5144430B1 (OSRAM)
DE (1) DE1929429C3 (OSRAM)
FR (1) FR2011101A1 (OSRAM)
GB (1) GB1261596A (OSRAM)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4789783A (en) * 1987-04-02 1988-12-06 Cook Robert D Discharge ionization detector
WO1990004852A1 (en) * 1988-10-27 1990-05-03 Battelle Memorial Institute Hollow electrode plasma excitation source
US4965540A (en) * 1987-12-23 1990-10-23 Hewlett-Packard Company Microwave resonant cavity
US5105123A (en) * 1988-10-27 1992-04-14 Battelle Memorial Institute Hollow electrode plasma excitation source
US5353113A (en) * 1993-07-15 1994-10-04 Cetac Technologies Incorporated Single and multiple radiation transparent afterglow electric discharge detector systems
US5382804A (en) * 1993-07-15 1995-01-17 Cetac Technologies Inc. Compact photoinization systems
WO1998039637A1 (de) * 1997-03-04 1998-09-11 Bernhard Platzer Vorrichtung zum analysieren gasförmiger proben

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54161219U (OSRAM) * 1978-05-01 1979-11-10
JPS54171925U (OSRAM) * 1978-05-22 1979-12-05
DE3405075A1 (de) * 1984-02-13 1985-08-14 Siemens AG, 1000 Berlin und 8000 München Vorrichtung zur atomspektroskopie einer analysensubstanz
DE3817502A1 (de) * 1987-05-22 1988-12-08 Palitex Project Co Gmbh Verfahren zum betrieb garnverarbeitender einrichtungen

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3458258A (en) * 1964-03-26 1969-07-29 Philips Corp Method of detecting a carbon in the gaseous phase
US3512030A (en) * 1967-06-16 1970-05-12 Vitro Corp Of America High intensity source of selected radiation

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3458258A (en) * 1964-03-26 1969-07-29 Philips Corp Method of detecting a carbon in the gaseous phase
US3512030A (en) * 1967-06-16 1970-05-12 Vitro Corp Of America High intensity source of selected radiation

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4789783A (en) * 1987-04-02 1988-12-06 Cook Robert D Discharge ionization detector
US4965540A (en) * 1987-12-23 1990-10-23 Hewlett-Packard Company Microwave resonant cavity
WO1990004852A1 (en) * 1988-10-27 1990-05-03 Battelle Memorial Institute Hollow electrode plasma excitation source
US5105123A (en) * 1988-10-27 1992-04-14 Battelle Memorial Institute Hollow electrode plasma excitation source
US5353113A (en) * 1993-07-15 1994-10-04 Cetac Technologies Incorporated Single and multiple radiation transparent afterglow electric discharge detector systems
US5382804A (en) * 1993-07-15 1995-01-17 Cetac Technologies Inc. Compact photoinization systems
WO1998039637A1 (de) * 1997-03-04 1998-09-11 Bernhard Platzer Vorrichtung zum analysieren gasförmiger proben
US6381014B1 (en) 1997-03-04 2002-04-30 Bernhard Platzer Device for analyzing gaseous samples

Also Published As

Publication number Publication date
DE1929429B2 (de) 1977-11-10
GB1261596A (en) 1972-01-26
JPS5144430B1 (OSRAM) 1976-11-29
DE1929429C3 (de) 1978-06-29
DE1929429A1 (de) 1969-12-18
FR2011101A1 (OSRAM) 1970-02-27

Similar Documents

Publication Publication Date Title
Frame et al. Microdischarge devices fabricated in silicon
KR960016169B1 (ko) 글로우 방전램프
US3685911A (en) Capillary arc plasma source for and method of spectrochemical analysis
Haidar Local thermodynamic equilibrium in the cathode region of a free burning arc in argon
Haidar et al. Temperature measurements for high-current free-burning arcs in nitrogen
US4812040A (en) Hollow cathode plasma plume
Zander et al. Determination of trace metals by microwave plasma spectrometry with an atmospheric pressure helium discharge
KennetháMarcus Inter-Laboratory note. Direct insertion probe for radiofrequency powered glow discharge mass spectrometry
Patel et al. Tubular electrode torch for capacitatively coupled helium microwave plasma as a spectrochemical excitation source
WO2022155727A1 (en) Inductively coupled plasma torches and methods and systems including same
Lazik et al. Effect of limiting orifice (anode) geometry in radio frequency glow discharge emission spectrometry
Uzelac et al. Measurement of gas temperatures and metastable state densities in a microwave boosted glow discharge using a diode laser
Reiche et al. Diagnostics of discharge modes of a free-burning low-current argon arc
US5483121A (en) Hollow cathode discharge tube
US5069546A (en) Atmospheric pressure capacitively coupled plasma spectral lamp
Bengtson Developments in glow discharge optical emission spectrometry. Invited lecture
US5731872A (en) Plasma manipulator
US2974256A (en) Light sources for the spectro-chemical analysis of substances
Marcus et al. The hollow cathode plume: A plasma emission source for solids
Broekaert et al. Investigations of a jet-assisted glow discharge lamp for optical emission spectrometry
EP0051152A1 (en) Optical coupling device
Grazhulene et al. The possibilities of glow discharge cathode sputtering for laser atomic-fluorescence analysis of microelectronics materials
Lopez-Urrutia et al. Absolute transition probabilities of Cu II lines
Karanassios et al. Electrically heated wire-loop, in-torch vaporization sample introduction system for inductively coupled plasma atomic emission spectrometry with photodiode array detection
Schroeder et al. Evaluation of a hollow cathode atomic emission source designed for continuous solution sample introduction

Legal Events

Date Code Title Description
AS Assignment

Owner name: JAMES TALCOTT, INC., NEW YORK

Free format text: SECURITY INTEREST;ASSIGNORS:APPLIED RESEARCH LABORATORIES, INC.;ARL APPLIED RESEARCH LABORATORIES, S.A.;REEL/FRAME:004326/0899

Effective date: 19840828

Owner name: LLOYDS BANK INTERNATIONAL LIMITED, NEW YORK

Free format text: SECURITY INTEREST;ASSIGNORS:APPLIED RESEARCH LABORATORIES, INC.;ARL APPLIED RESEARCH LABORATORIES, S.A.;REEL/FRAME:004326/0899

Effective date: 19840828

Owner name: E.I. DU PONT DE NEMOURS AND COMPANY, DELAWARE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BUCKFELDER, JOHN J.;SCHLEINITZ, HENRY M.;REEL/FRAME:004326/0513

Effective date: 19840925

Owner name: JAMES TALCOTT, INC., 1633 BROAWAY NEW YORK, NY 10

Free format text: SECURITY INTEREST;ASSIGNORS:APPLIED RESEARCH LABORATORIES, INC., A MA CORP.;ARL APPLIED RESEARCH LABORATORIES, S.A. A SWITZERLAND CORP.;REEL/FRAME:004326/0899

Effective date: 19840828

Owner name: LLOYDS BANK INTERNATIONAL LIMITED, ONE SEAPORT PLA

Free format text: SECURITY INTEREST;ASSIGNORS:APPLIED RESEARCH LABORATORIES, INC., A MA CORP.;ARL APPLIED RESEARCH LABORATORIES, S.A. A SWITZERLAND CORP.;REEL/FRAME:004326/0899

Effective date: 19840828

Owner name: E.I. DU PONT DE NEMOURS AND COMPANY, WILMINGTON, D

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:BUCKFELDER, JOHN J.;SCHLEINITZ, HENRY M.;REEL/FRAME:004326/0513

Effective date: 19840925