US3546521A - Low-pressure gas discharge lamp for producing resonance radiation - Google Patents

Low-pressure gas discharge lamp for producing resonance radiation Download PDF

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Publication number
US3546521A
US3546521A US751474A US3546521DA US3546521A US 3546521 A US3546521 A US 3546521A US 751474 A US751474 A US 751474A US 3546521D A US3546521D A US 3546521DA US 3546521 A US3546521 A US 3546521A
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United States
Prior art keywords
radiation
lamp
absorption
atom source
discharge
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Expired - Lifetime
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US751474A
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English (en)
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Zeger Van Gelder
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/10—Shields, screens, or guides for influencing the discharge

Definitions

  • a low-pressure gas discharge lamp for producing resonance radiation employing a pair of electrodes with an envelope containing a rare gas. A positive column is maintained between the electrodes during operation of the lamp, the column having an axis which intersects a window in the envelope for transmitting the radiation.
  • An atom source containing an element the resonance radiation of which is desired surrounds the positive column while a ring around the discharge path between the atom source and the window is provided which is spaced from the atom source a distance which is smaller than the length of the atom source and the inner surface of which has a perpendicular section which is smaller than that of the inner surface of the atom source.
  • the length of this ring is at least equal to the largest dimension of the perpendicular section of the inner surface.
  • the invention relates to low-pressure gas discharge lamps for producing resonance radiation. Such lamps are frequently used in spectroscopy and particularly in resonance-absorption spectroscopy.
  • gas discharge lamps for producing resonance radiation which have an anode and a hollow cylindrical cathode which consists wholly or partly of the material the resonance radiation of which is desired.
  • Cathode material is sputtered by bombardment of ions and as a result the concentration of the atoms of the above-mentioned material in the hollow cathode will strongly increase.
  • These atoms may be excited by the electrons from the discharge and subsequently emit, inter alia, their resonance radiation.
  • the radiation is used for absorption spectroscopy, the sample to be examined being arranged in alignment with the axis of the hollow cathode.
  • the line shape of the resonance radiation of these known lamps is determined in the first instance by the so-called Doppler broadening.
  • the Doppler broadening dependent on the temperature of the atomic vapour, may be slight in these lamps and gives rise to the Doppler profile associated with this temperature.
  • the narrow Doppler profile Due to absorption of resonance radiation by unexcited atoms, the narrow Doppler profile is, however, considerably broadened and truncated. Since this absorption takes place in the lamp itself, the term self-absorption is often used. Two regions in the lamp where the said self-absorption occurs can be distinguished:
  • the absorption broadening is a function of the product of the length of the hollow cathode and the absorption coefiicient which latter is proportional to the atom concentration.
  • the intensity of the radiation is proportional to the product of the electron concentration and the atom concentration.
  • absorption spectroscopy it is desired to have radiation of high intensity and narrow line profile. To obtain such a radiation it is therefore necessary to achieve a high electron concentration and a low atom concentration.
  • these concentrations cannot be controlled independent of each other since both are determined by the discharge between hollow cathode and anode.
  • the effective radiation emerging from the lamp along the axis of the hollow cathode comprises the sum of the radiation obtained by excitation of atoms in the positive column and the radiation produced in the hollow cathode.
  • the first-mentioned part adds a narrow peak to the profile at the resonance frequency which reduces the dip of the radiation profile originating from the hollow cathode and increases the total intensity.
  • the profile width of the total radiation remains as unfavourable as in the case of the hollow cathode.
  • this known lamp has the additional drawback of self-absorption outside the region of discharge, inter alia, between the discharge and the window in the envelope.
  • a low-pressure gas discharge lamp for producing resonance radiation comprises a. discharge space filled with a rare gas and having an envelope provided with a window which passes the radiation produced and further comprises two electrodes between which a positive column discharge is maintained during operation of the lamp, and an atom source containing an element the resonance radiation of which is desired, and is characterized in that the axis of the positive column discharge intersects the window, that the atom source surrounds the positive column and that a ring is provided around the discharge path between atom source and window, which ring extends up to the vicinity of the atom source and the inner surface of which has a perpendicular section which is smaller than that of the inner surface of the atom source, the length of said ring being at least equal to the largest dimension of the perpendicular section of its inner surface.
  • the envelope of the discharge space consists, for example, of glass or quartz glass.
  • the space is filled with a rare gas, for example, argon or neon or a mixture of these gases.
  • the pressure of the rare gas is preferably not higher than 5 mm. Hg, because at higher pressures the spectral profile is broadened unfavourably as a result of Lorentz broadening.
  • the electrodes between which the column discharge takes place are an anode and a cathode, preferably a filament cathode.
  • the atom source comprises at least partially the element or elements the resonance radiation of which is desired and is mostly a sputtering electrode which, during operation of the lamp, is brought to a potential which is negative relative to the plasma potential of the positive column.
  • the sputtering electrode is preferably cylindrically shaped by bending of a plate or a gauze wire, but it is alternatively possible to construct a cylindrical cage having bars of the desired material.
  • Elements having a high vapour pressure at temperatures lower than the operating temperature of the lamp, or having a softening point in the vicinity of that temperature may be used to manufacture compounds having a much lower vapour pressure and/ or a higher softening point than that of the relevant element.
  • the sputtering electrode may then contain these compounds.
  • the sputtering electrode may, for example, comprise a porous, high-melting-point and electrically conducting material such as sintered nickel, tungsten or molybdenum, incorporating the elements having a high vapour pressure or a low melting point, or compounds of these elements. In certain cases it is then desirable to surround the sputtering electrode by a casing which is impermeable to those elements.
  • the sputtering electrode may alternatively be designed in a manner known for storage cathodes. It is alternatively possible for the atom source to supply the desired vapour by heating a carrier containing the relevant material. In that case the atom source may, for example, be constructed as a coil having one or more turns about the discharge path and being heated by an electric current'
  • the ring is mostly cylindrical, but it may alternatively assume the shape of a composition of diaphragms. In any case the conditions must be fulfilled that the internal diameter of the ring is smaller than that of the atom source, and that the length of the ring is at least equal to the internal diameter.
  • the ring extends up to the vicinity of the atom source is understood to mean that the distance between ring and atom source is smaller than the length of the atom source. Part of the ring may, however, be located within the atom source.
  • the ring preferably makes no mechanical contact with the atom source. If the atom source is designed as a sputtering electrode such a contact is undesirable because in that case not only the atoms adsorbed at the ring may contribute, through bombardment of ions, to sputtering but also material of the ring may be brought in the discharge.
  • An important advantage of a lamp according to the invention is that the radiation emerges along the axis of the positive column discharge. As a result the radiation produced does not pass any region in the lamp where strong absorption may occur without excitation by electrons also taking place, as is indeed the case in the known lamps.
  • the rings provide the further advantage that they concentrate the positive column discharge in a narrow beam having a high concentration of electrons.
  • the highest concentration of electrons in the atom source is found along the axis, whereas the concentration of atoms is lowest in that area.
  • the latter fact is the result of the ionization of the vapour atoms which is strongest on the axis due to the high density of electrons in that area. Since the ambipolar diffusion coefficient of the vapour ions travelling towards the wall is much higher than the diffusion coefiicient of the neutral vapour atoms moving towards the axis to eliminate the shortage occurring in that area, the decrease in the density of the neutral vapour atoms on the axis will be much greater than the increase in the density of the ions on the axis.
  • the rings have the further advantage that they pass the radiation from the vicinity of the axis and that they do not pass the radiation coming from areas along the wall of the atom source.
  • the spectral distribution of the emerging radiation then hardly deviates from the Doppler profile.
  • the ring or rings are preferably manufactured of an electrically insulating material, for example, glass or ceramic material.
  • the rings are supported by disc-like plates adjoining the envelope of the discharge space and preferably of an electrically insulating material, for example, glass, ceramic material or mica.
  • a very advantageous embodiment is the one in which a plurality of atom sources is present each of which may form the vapour of a different element and which are separated from one another by rings. Without the necessity of exchanging a lamp the resonance radiation of various elements can be produced separately by activating the relevant atom source either by applying a negative potential or by connecting a heating current.
  • the rings prevent the possibility of deposition of atoms of one atom source into another atom source.
  • FIG. 1 is a sectional view of an embodiment of a lamp according to the invention
  • FIG. 2 shows a further embodiment
  • FIG. 3 shows an embodiment having a plurality of atom sources.
  • FIG. 4 is a graph showing the absorption sensitivity of a lamp according to the invention and of a few known lamps, plotted as a function of the intensity.
  • the lamp of FIG. 1 includes a glass envelope 1 having a quartz-glass window 2 and is filled with argon up to a pressure of 3 mm. Hg.
  • a cathode 3 is a filament cathode covered with an emitting material; an anode 4 is a rod of tungsten.
  • the atom source 5 is a sputtering electrode in the form of a copper cylinder having an internal diameter of 1 cm. and a length of 2 cm.
  • the argon ions from the positive column discharge between the electrodes 3 and 4 will cause copper atoms to be sputtered from the sputtering electrode 5 if this electrode is supplied with a negative potential.
  • Cylindrical rings 6 of glass are placed on either side of the sputtering elec trode 5. These rings have an internal diameter of 4 mm. and an external diameter of 8 mm. They extend over a distance of approximately 3 mm. within the sputtering electrode, but do not make contact therewith. The length of the rings is 2 cm.
  • the rings 6 are held in place by ceramic plates 7 which extend up to the lamp envelope. The rings 6 limit the copper vapour to within the space of the sputtering electrode 5.
  • FIG. 2 deviates from that of FIG. 1 in that the three electrodes 3, 4 and 5 are placed in one line and that the anode 4 is provided with a hole 8 which passes the radiation.
  • the rings 6 have in this case the shape of a diaphragm provided with a cylindrical portion.
  • FIG. 3 shows an embodiment in which two sputtering electrodes are used, namely one for calcium 9 and one for magnesium 10.
  • the two electrodes enclose a glass ring 11 which prevents magnesium vapour from depositing on the inner side of the sputtering electrode containing calcium, and conversely.
  • the cathode side of the ring 12 has a widening which adjoins the envelope 1 of the lamp so that the column discharge bypassing the atom source is prevented.
  • the intensity I of the radiation passed through the furnace was measured and the absorption sensitivity of the lamps in said medium is plotted in the graphs rv- 1 n as a function of the intensity I of the radiation produced by the lamp, said absorption sensitivity being defined by
  • the resonance radiation of the element copper is produced in a lamp according to the invention as described hereinbefore with reference to FIG. 2, and the intensity I of the radiation is varied with the aid of the sputteringelectrode current.
  • the curve (a) shows the variation of the absorption sensitivity of the lamp according to the invention as a function of I and it is found that said sensitivity remains substantially constant up to very high values of I
  • the curve (b) gives as a function of I for a lamp having a hollow cathode of copper.
  • the same small furnace has been used as an absorptive medium. In this case I is varied with the aid of the hollow cathode current.
  • the absorption sensitivity is found to be quickly decreasing with I increasing.
  • I0-I1 n is given in curve (0) as a function of I
  • the coppercontaining furnace has again been used as absorptive me dium and I has been varied with the aid of the hollow cathode current.
  • the absorption sensitivity is found to be dependent on I although to a lesser degree.
  • the absorption sensitivities of the said lamps are compared with one another in a different medium, namely an atmospheric flame, which is much used in absorption measurements.
  • the temperature of this flame is approximately 2500 C. and the absorption pro file is consequently much broader than that of the coppercontaining furnace. This has the result that the differences in absorption sensitivity of the lamps are smaller in this case.
  • a low-pressure gas discharge lamp for producing resonance radiation comprising a discharge space filled with a rare gas and having an envelope provided with a window which passes the radiation produced, two spaced electrodes between which a positive column discharge having a given axis which intersects the window is maintained during operation of the lamp, a cylindrical atom source having a given length surrounding the positive column and containing an element the resonance radiation of which is desired and defining a discharge path with the window, and an annular ring around the discharge path between said atom source and said window, said ring being spaced from the atom source a distance which is smaller than the length of the atom source and the inner surface of which has a perpendicular section which is smaller than that of the inner surface of the atom source, the length of said ring being at least equal to the largest dimension of the perpendicular section of its inner surface.
  • a low-pressure gas discharge lamp for producing resonance radiation as claimed in claim 1 wherein a ring is provided around the discharge path also on the side of the atom source remote from the window.

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  • Discharge Lamp (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
US751474A 1967-08-25 1968-08-09 Low-pressure gas discharge lamp for producing resonance radiation Expired - Lifetime US3546521A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL676711757A NL155127B (nl) 1967-08-25 1967-08-25 Lage druk-gasontladingslamp voor het opwekken van resonantiestraling.

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US3546521A true US3546521A (en) 1970-12-08

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US751474A Expired - Lifetime US3546521A (en) 1967-08-25 1968-08-09 Low-pressure gas discharge lamp for producing resonance radiation

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US (1) US3546521A (de)
JP (1) JPS4840990B1 (de)
AT (1) AT287848B (de)
BE (1) BE719926A (de)
CH (1) CH497044A (de)
DE (1) DE1764857A1 (de)
FR (1) FR1577722A (de)
GB (1) GB1214179A (de)
IL (1) IL30602A (de)
NL (1) NL155127B (de)
SE (1) SE340484B (de)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3601489A (en) * 1968-09-04 1971-08-24 Philips Corp Gas-discharge lamp for producing modulated atomic resonance radiation
JPS4936183A (de) * 1972-08-05 1974-04-03
US3851213A (en) * 1971-10-28 1974-11-26 Philips Corp Arrangement for generating modulated atomic resonance
JPS5199093A (ja) * 1976-01-26 1976-09-01 Hamamatsu Tv Co Ltd Supekutoruhodenkan
FR2494498A1 (fr) * 1980-11-18 1982-05-21 Narva K Lampe a decharge a gaz a basse pression
US5907222A (en) * 1993-11-03 1999-05-25 Litton Systems, Inc. High efficiency backlighting system for rear illumination of electronic display devices
US20080054812A1 (en) * 2006-08-29 2008-03-06 Osram Sylvania Inc. Arc discharge vessel having arc centering structure and lamp containing same
US20090310134A1 (en) * 2006-03-21 2009-12-17 Masaru Hori Multi Micro-Hollow Cathode Light Source and Multi-Atomic Simulataneous Absorption Spectrum Analyzer

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19628925B4 (de) * 1996-07-18 2004-07-01 Heraeus Noblelight Gmbh Entladungslampe mit einer Füllung, die Deuterium, Wasserstoff, Quecksilber, ein Metallhalogenid oder Edelgas aufweist
JP4964374B2 (ja) * 2001-08-24 2012-06-27 浜松ホトニクス株式会社 ガス放電管
JP4964360B2 (ja) * 2000-11-15 2012-06-27 浜松ホトニクス株式会社 ガス放電管
JP4907760B2 (ja) 2000-11-15 2012-04-04 浜松ホトニクス株式会社 ガス放電管
JP4964359B2 (ja) * 2000-11-15 2012-06-27 浜松ホトニクス株式会社 ガス放電管
JP4907852B2 (ja) * 2004-08-24 2012-04-04 浜松ホトニクス株式会社 ガス放電管

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2050341A (en) * 1928-10-06 1936-08-11 Westinghouse Electric & Mfg Co Glow lamp
US2763806A (en) * 1950-11-24 1956-09-18 Hanovia Chemical & Mfg Co Vapor electric discharge device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2050341A (en) * 1928-10-06 1936-08-11 Westinghouse Electric & Mfg Co Glow lamp
US2763806A (en) * 1950-11-24 1956-09-18 Hanovia Chemical & Mfg Co Vapor electric discharge device

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3601489A (en) * 1968-09-04 1971-08-24 Philips Corp Gas-discharge lamp for producing modulated atomic resonance radiation
US3851213A (en) * 1971-10-28 1974-11-26 Philips Corp Arrangement for generating modulated atomic resonance
JPS4936183A (de) * 1972-08-05 1974-04-03
JPS5199093A (ja) * 1976-01-26 1976-09-01 Hamamatsu Tv Co Ltd Supekutoruhodenkan
FR2494498A1 (fr) * 1980-11-18 1982-05-21 Narva K Lampe a decharge a gaz a basse pression
US5907222A (en) * 1993-11-03 1999-05-25 Litton Systems, Inc. High efficiency backlighting system for rear illumination of electronic display devices
US20090310134A1 (en) * 2006-03-21 2009-12-17 Masaru Hori Multi Micro-Hollow Cathode Light Source and Multi-Atomic Simulataneous Absorption Spectrum Analyzer
US20080054812A1 (en) * 2006-08-29 2008-03-06 Osram Sylvania Inc. Arc discharge vessel having arc centering structure and lamp containing same
US7619350B2 (en) * 2006-08-29 2009-11-17 Osram Sylvania Inc. Arc discharge vessel having arc centering structure and lamp containing same

Also Published As

Publication number Publication date
DE1764857A1 (de) 1971-11-18
JPS4840990B1 (de) 1973-12-04
FR1577722A (de) 1969-08-08
NL155127B (nl) 1977-11-15
SE340484B (de) 1971-11-22
GB1214179A (en) 1970-12-02
IL30602A0 (en) 1968-10-24
BE719926A (de) 1969-02-24
IL30602A (en) 1972-01-27
NL6711757A (de) 1969-02-27
AT287848B (de) 1971-02-10
CH497044A (de) 1970-09-30

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