GB2259767A - Laser Raman measuring cell - Google Patents

Laser Raman measuring cell Download PDF

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Publication number
GB2259767A
GB2259767A GB9214803A GB9214803A GB2259767A GB 2259767 A GB2259767 A GB 2259767A GB 9214803 A GB9214803 A GB 9214803A GB 9214803 A GB9214803 A GB 9214803A GB 2259767 A GB2259767 A GB 2259767A
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GB
United Kingdom
Prior art keywords
sample chamber
measuring cell
laser raman
windows
laser
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.)
Granted
Application number
GB9214803A
Other versions
GB9214803D0 (en
GB2259767B (en
Inventor
Ulla Engelmann
Manfred Glugla
Ralf-Dieter Penzhorn
Karl Heinz Simon
Hans-Joachim Ache
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.)
Forschungszentrum Karlsruhe GmbH
Original Assignee
Kernforschungszentrum Karlsruhe GmbH
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.)
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Publication date
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Publication of GB9214803D0 publication Critical patent/GB9214803D0/en
Publication of GB2259767A publication Critical patent/GB2259767A/en
Application granted granted Critical
Publication of GB2259767B publication Critical patent/GB2259767B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65Raman scattering
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03Cuvette constructions
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01JMEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28Investigating the spectrum
    • G01J3/44Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/63Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
    • G01N21/65Raman scattering
    • G01N2021/651Cuvettes therefore
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03Cuvette constructions
    • G01N21/031Multipass arrangements

Abstract

The cell (5) for analytical investigation of gases comprises a basic body member made of metal including a vacuum- tight sample chamber (4) coated with black enamel; at least two windows (3, 6, 8, 11) permeable to Laser and Raman radiation seal the sample chamber in a vacuum-tight manner and are offset in relation to one another in one plane at an angle of 90 DEG ; and one or more connections (14) for evacuating and filling the sample chamber with a gaseous sample. <IMAGE>

Description

1) r, c -.' 1 LASER RAMAN MEASURING CELL The present invention relates to
a Laser Raman measuring cell for analytical investigation of gases or gas mixtures, and in particular to a Laser Raman measuring cell having a considerably reduced proportion of scattered light.
Raman spectroscopy is a spectroscopy of scattered radiation which is observed when light is radiated, generally at right angles to the direction of observation, into a Raman-active medium. However, in the analysis of gases in particular, the Raman lines are generally extremely weak. Raman spectroscopy has only achieved analytical importance since laser radiation has become available as a light-source.
Laser Raman spectroscopy (LRS) is suitable f or analytical detection of a plurality of gasesf particularly of those with symmetrical molecules without dipole moment, which cannot be detected by infrared spectroscopy (Frenesius, Z. Anal. Chem., vol. 327, 1987f pages 335 to 337). Laser Raman spectroscopy is particularly suitable for analysis of hydrogen and, in this case above all, for determining the content of hydrogen isotopes. The Raman lines of each of the possible isotope compounds H2, D2f T2 HD, HT and DT can be resolved by conventional spectrometers.
Analysis of hydrogen isotopes is described in the publication of T. Uda, K. Okuno, S. Olhira and Y. Naruse entitled "Application Study of Laser Raman Spectroscopy to In Situ Gas Analysis for Fusion Fuel Processing Systems" in the conference report of the 9th Topical Meeting on the Technology of Fusion Energy, Oak Brook, Illinois, USA, (Oct. 1990). A cuboid glass body with square cross-section, surrounding a sample chamber of about 6 cm3, is used. A connector nozzle of glass is cast in place in the centre of one of the sides, through which the sample chamber can be evacuated and f illed. The laser light falls through one of the square sides into the sample chamber. The Raman radiation is passed through the side opposite the connector nozzle, into a monochromator.
For several reasons, this measuring cell represents a provisional solution. The glass connector nozzle has to be connected to a vacuumtight metallic fitting. Further, the glass surfaces through which the laser or Raman light is coupled or uncoupled consist of optical windows. Optical windows can only be used when the glass surf aces f rom which the cell is constructed are glued together, in which case organic adhesives would have to be used which can react with the glass, or fused together, in which case the optical quality of the windows would be impaired. In either case finishing work can only be carried out on the outer surfaces of the windows. Further, the cell appears unsuitable for measurements at high pressure.
There is a brief description of a further measuring cell for the LRS of hydrogen isotopes in the publication 11Raman Line Positions in Molecular Hydrogen: H2, HD, HT, D2, DT and T211 by D. Kirk Veirs and Gerd M. Rosenblatt, Journal of Molecular Spectroscopy 121, 401419 (1987). It is merely known from this publication that the measuring cell is made of aluminium and contains coated windows which are sealed by metallic 0rings. The sample chamber volume is given as 1.3 cm3
More specific details on this cell are contained in the publication of Dean H. W. Carstens, "An Apparatus f or Studies of Hydrogen Isotope Exchange over Metals using Laser-Raman Spectroscopyll, Los Alamos National Laboratory, LA-11884-MS, UC-704 (Oct. 1990). According to this document the measuring cell comprises a block of aluminium, in which a hole f or the laser beam is bored along the longitudinal axis. Attached at the ends of the block are coated quartz glass windows sealed by 0rings. Additional and larger windows at right angles to the laser beam enable observation of the Raman light.
A measuring cell whose sample chamber consists of aluminium appears less suitable for LRS as a high background results during measurement because of the diffuse reflections, particularly in the case of small sample volumes.
Small sample volumes are particularly required for measuring cells into which highly toxic, aggressive or radioactive gases are introduced. With small sample volumes the proportion of scattered light increases sharply, so that a high background results during measurement.
A Laser Raman measuring cell of the type already mentioned is known from the publication Rev. Sci. Instrum. vol. 57, 1986, pages 2507 to 2511.
In this measuring cell the proportion of scattered light arising from diffuse reflections is reduced by screens and guide plates and by a black coating in the sample chamber, produced by anodic oxidation. Anodic oxidation is usable on few materials, but particularly on aluminium. In order to provide black coloration in the coating, organic dyestuffs and/or organic salts must be used, which are not stable in laser light.
A further measuring cell of the type already mentioned, yet without a black coating in the sample chamber, is known from US-PS 4,676,639.
In this measuring cell the diffuse scattered light is minimised by screens alone.
There is known from DE 23 63 180 C2 a reactionkinetic measuring apparatus containing a measuring cell of stainless steel, whose core consists of a black plastic material in order to reduce diffuse scattered light. In this case the core surrounds the sample chamber. The black plastic (polyacetal resin) also has poor stability in scattered laser light.
A further Laser Raman measuring cell is described in the 11Zeitschrift filr Naturforschung, vol. 28a, 1973, bk. 1, pages 27 to 30. This measuring cell consists of stainless steel and contains no measures to minimise diffuse scattered light.
The object of the present invention is to provide a measuring cell suitable for LRS in which the proportion of scattered light is considerably reduced. In the connected-up state, the measuring cell is to be vacuum-tight or ultra-high-vacuum-tight. The gas sample is not to come into contact with unstable, particularly organic materials. Further, the construction is to permit the use of optical windows of high quality.
According to the present invention there is provided a Laser Raman measuring cell comprising: a basic body member made of metal including a vacuum-tight sample chamber covered with a black enamel coating; at least two windows permeable to Laser and Raman radiation, said windows sealing the sample chamber vacuum-tight and being disposed in a plane relative to one another which is offset through 900; and one or more connections for evacuating the sample chamber and filling the sample chamber with a gaseous sample.
The measuring cell according to the preferred embodiment of the present invention comprises a metallic basic body member made of stainless steel which contains a sample chamber for the gases to be measured which is coated in black enamel. The proportion of scattered light arising from diffuse reflections in the sample chamber is particularly effectively reduced by black enamel. Enamelling can be applied later to the previous ly-manuf actured basic body member, so that the latter can be manufactured in the conventional manner. A further advantage of the enamel coating is that the sample chamber is then inert against most gases, which is of particular importance when gas samples containing radioactive tritium are used.
Black enamel has been known per se f or a long time, i. e. from Ullmann 1 s Enzyklopadie der technischen Chemie, vol. 6, 3rd ed., Urban & Schwarzenberg, MUekenBerlin, 1955, pages 478 to 492. However, it has not previously been used for coating the sample chamber of a Laser Raman measuring cell.
In its simplest embodiment the measuring cell contains two windows which seal the sample chamber in a vacuum-tight or ultra-high-vacuum-tight manner, and are off set to one another in one plane through an angle of 900. The laser bean is coupled through the first window into the sample chamber and the Raman radiation is passed through the second window, disposed at right angles to the first window, into a monochromator.
An improved embodiment contains a further window, which in turn is disposed at right angles to the second window and thus lies opposite the first window.
Such an embodiment permits a so-called 11multipass11 measuring arrangement, in which the laser beam is reflected by mirrors and thus multiplies radiation through the sample chamber.
The preferred embodiment contains four windows, arranged in pairs opposite one another. In this embodiment the Raman light shining through the fourth window can be reflected by a further mirror, so that double the Raman light intensity passes into the monochromator.
The windows used may, for example, be sapphire or quartz glass windows, preferably with an evenness of less than 1 lambda, better still with an evenness of less than 1110 lambda.
Particularly preferred are optical windows manufactured by a diffusion welding process. Such windows comprise, for example, a quartz glass or sapphire pane secured by a metallic ring, for example of tantalum or titanium. The metallic ring is welded to the pane with the aid of an aluminium alloy as a connecting material at high pressure at a temperature of approximately 5000C. In the case of windows produced in this way, the optical quality of the quartz glass or of the sapphire is maintained; moreover, an ultra-highvacuum-tight measuring cell can be constructed with such windows without the use of organic sealant materials.
o C The sample chamber is most simply f ormed by bores originating from the openings f or the windows, extending perpendicularly to the window surface and intersecting one another in the interior of the basic body member.
Stainless steel is preferred as a material f or the basic body member, because it is easily provided with a strongly-bonded and dense enamel coating. An enamel coating melted from a frit with the principal ingredients Si02 B2031 Zr02, P203, alkaline metal and alkaline earth metal oxides, has proved particularly suitable for coating a basic body member made of stainless steel.
Particularly preferred composition:
Si02 B203 Zr02 P203 Na20 K20 Li20 CaO BaO MnO CUO coo is a f rit with the 20.0% 17.0% 10.0% 22.0% 6.0% 2. 0% 2. 0% 1.5% 16.5% 2.0% 0.5% 0.5% In order to produce the enamel coating, enamel frit together with a suitable binding agent, is applied, e.g. with a paintbrush, to the surface of the sample chamber. During subsequent firing the enamel coating formsf and the binding agent evaporates. it is recommended that all the edges of the sample chamber be rounded off by means of enamelling.
electroerosion before A preferred embodiment of the present invention will now be described by way of example with reference to the accompanying drawing in which the preferred embodiment of the present invention in a measuring arrangement is shown.
A laser beam 1 is radiated by a mirror 2 through the window 3 into the sample chamber 4 of the measuring cell 5. The beam leaving the sample chamber 4 through the window 6 is reflected at mirrors 7 and 2. Raman radiation is passed through window 8 and through slot 9 into the monochromator 10. The Raman radiation leaving the sample chamber 4 through the window 11 is reflected by mirror 12, and likewise passes into the monochromator 10.
The measuring cell comprises a basic body member made of stainless steel in which crucif orm bores f orm the sample chamber 4. The sample chamber is coated with black enamel 13. The diameter of the bores f or the Raman radiation is slightly larger than the diameter for the laser radiation (1lmm compared to 9mm). The bores are expanded at their outer end to receive the windows 3, 6, 8, 11. The windows are secured by UHV f langes (not illustrated) such as ConflatR- (CF-) flanges (Trade Mark of the Varian Company), and sealed with the aid of flat seals of copper. The sample chamber 4 is evacuated and filled with a gas sample through connections 14.

Claims (6)

  1. Laser Raman measuring cell comprising:
    a basic body member made of metal including a vacuum-tight sample chamber covered with a black enamel coating; at least two windows permeable to Laser and Raman radiation, said windows sealing the sample chamber vacuum-tight and being disposed in a plane relative to one another which is offset through 900; and one or more connections for evacuating the sample chamber and filling the sample chamber with a gaseous sample.
  2. 2. Laser Raman measuring cell according to claim 1, wherein three windows are provided.
  3. 3. Laser Raman measuring cell according to claim 1, wherein four windows are provided.
  4. 4. Laser Raman measuring cell according to claims 1, 2 or 3, wherein the sample chamber is formed by cylindrical bores disposed vertically relative to the window surfaces and intersect in the interior of the basic body member.
  5. 5. Laser Raman measuring cell according to any of claims 1 to 4, wherein the metal of the basic body member is stainless steel.
  6. 6. Laser Raman cell according to any of claims 1 to 5, wherein a frit used to produce the black enamel has the principal ingredients Si02, B203, Zr02, P203, alkaline metal and alkaline earth metal oxides.
    7 Laser Raman cell according to claim 6, wherein - 10 the composition of the frit is as follows:
    Si02 B203 Zr02 P203 Na20 K20 Li20 CaO BaO MnO CUO coo 8. Laser Raman measuring hereinbefore described with accompanying drawing.
    1 20.0% 17.0% 10.0% 22.0% 6.0% 2. OP-o' 2.0% 1.5% 16.5% 2.0% 0.5% 0.5% cell substantially as reference to the 1 -1
GB9214803A 1991-08-22 1992-07-13 Laser raman measuring cell Expired - Fee Related GB2259767B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19914127712 DE4127712C2 (en) 1991-08-22 1991-08-22 Laser Raman measurement cell

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GB9214803D0 GB9214803D0 (en) 1992-08-26
GB2259767A true GB2259767A (en) 1993-03-24
GB2259767B GB2259767B (en) 1995-06-14

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009101418A1 (en) * 2008-02-12 2009-08-20 Starna Scientific Limited Reference cell
WO2013087656A1 (en) * 2011-12-16 2013-06-20 Glaxo Group Limited Apparatus for testing samples using raman radiation
US10094781B2 (en) 2014-04-14 2018-10-09 General Electric Company Methods and systems to analyze a gas-mixture

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4320943C2 (en) * 1993-06-24 2001-02-15 Lavision Gmbh Method for characterizing the operation of internal combustion engines by measuring the gas composition in the combustion chamber by Raman spectroscopy
CN110231330A (en) * 2019-05-31 2019-09-13 南方科技大学 A kind of method of single cell Raman spectrum technology measurement ammoxidation archaeal metabolic activity

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4676639A (en) * 1986-01-22 1987-06-30 Biomaterials International, Inc. Gas cell for raman scattering analysis by laser means

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2363180C2 (en) * 1973-12-19 1984-05-10 Max Planck Gesellschaft zur Förderung der Wissenschaften e.V., 3400 Göttingen Reaction kinetic measuring device

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4676639A (en) * 1986-01-22 1987-06-30 Biomaterials International, Inc. Gas cell for raman scattering analysis by laser means

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009101418A1 (en) * 2008-02-12 2009-08-20 Starna Scientific Limited Reference cell
GB2457449B (en) * 2008-02-12 2011-06-15 Starna Scient Ltd Reference cell
WO2013087656A1 (en) * 2011-12-16 2013-06-20 Glaxo Group Limited Apparatus for testing samples using raman radiation
CN104115002A (en) * 2011-12-16 2014-10-22 葛兰素集团有限公司 Apparatus for testing samples using Raman radiation
JP2015500492A (en) * 2011-12-16 2015-01-05 グラクソ グループ リミテッドGlaxo Group Limited Apparatus for testing samples with Raman radiation
AU2012350656B2 (en) * 2011-12-16 2015-04-30 Glaxo Group Limited Apparatus for testing samples using Raman radiation
US9261404B2 (en) 2011-12-16 2016-02-16 Glaxo Group Limited Apparatus for testing samples using raman radiation
US10094781B2 (en) 2014-04-14 2018-10-09 General Electric Company Methods and systems to analyze a gas-mixture
US10495578B2 (en) 2014-04-14 2019-12-03 General Electric Company Methods and systems to analyze a gas-mixture

Also Published As

Publication number Publication date
FR2680571A1 (en) 1993-02-26
GB9214803D0 (en) 1992-08-26
GB2259767B (en) 1995-06-14
DE4127712A1 (en) 1993-02-25
DE4127712C2 (en) 1993-10-07

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19980713