GB2155664A - Pyrolysis mass spectrometer - Google Patents
Pyrolysis mass spectrometer Download PDFInfo
- Publication number
- GB2155664A GB2155664A GB08406773A GB8406773A GB2155664A GB 2155664 A GB2155664 A GB 2155664A GB 08406773 A GB08406773 A GB 08406773A GB 8406773 A GB8406773 A GB 8406773A GB 2155664 A GB2155664 A GB 2155664A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sample
- temperature
- mass spectrometer
- pyrolysis
- heating
- 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.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J49/0468—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components with means for heating or cooling the sample
- H01J49/0486—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components with means for heating or cooling the sample with means for monitoring the sample temperature
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J49/0468—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components with means for heating or cooling the sample
- H01J49/0472—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components with means for heating or cooling the sample with means for pyrolysis
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Radiation Pyrometers (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Method of pyrolysing a sample for analysis in a mass spectrometer, which comprises providing a transparent window (10) in the vacuum envelope of the mass spectrometer for permitting the sample (12) to be viewed during pyrolysis. The blackbody radiation emitted during heating is monitored to provide an electrical signal indicative of the temperature and the heating source (20) is controlled in dependence upon the sensed temperature in such a manner as to maintain the pyrolysis temperature at a predetermined value.
Description
SPECIFICATION
Pyrolysis mass spectrometer
The invention relates to a pyrolysis mass spectrometer.
In a pyrolysis mass spectrometer, the particles used to form the ion beam are produced
by pyrolysing a sample to be analysed. The
degree to which the sample is broken down
depends upon the temperature of the pyro
lysis and it is therefore important to reguiate the temperature with precision.
One known way for pyrolysing a sample employs the principle of Curie point heating.
The sample is placed on a ferromagnetic boat and heated by passing current through a coil surrounding the boat. The losses caused by
magnetic hysteresis raise the temperature of the boat rapidly but on reaching the Curie point, no further heating occurs due to the change in the magnetic properties of the
material. Thus the boat and the sample could be raised rapidly to an accurately predetermined temperature. However, the temperaure is predetermined by the material use in the making of the boat and cannot be varied at will.
Other methods of heating sample in order to pyrolyse it have also been proposed but they suffer from the disadvantage that it is difficult to regulate the temperature.
The present invention seeks to provide a method of pyrolysing a sample which offers greater flexibility than Curie point heating in determining the temperature of analysis, yet permits the temperature to be controlled accurately.
According to the present invention, there is provided a method of pyrolysing a sample for analysis in a mass spectrometer, which comprises providing a transparent window in the vacuum envelope of the mass spectrometer for permitting the sample to be viewed during pyrolysis, heating the sample by a controllable heating source, monitoring the blackbody radiation emitted during the heating to provide an electrical signal indicative of the temperature and controlling the heating source in dependence upon the the sensed temperature in such a manner as to maintain the pyrolysis temperature at a predetermined value.
The sample may conveniently be mounted on a transparent slide or within a transparent tube forming part of the vacuum envelope of the spectrometer.
Preferably, the sample is supported on a substrate having a coating of predetermined emissivity. For example, the sample may rest on a glass slide having a coating of high emissivity or it may rest on a foil provided a coating of high emissivity. In the latter case, it is further preferred that the radiation from the side of the foil not in contact with the sample be used to indicate the pyrolysis temperature as the measurement is not then affected by the emissivity of the sample.
Though the heating may be effected by
means of an electrical heating element, it is
preferred that the energy from a radiant energy source disposed outside the vacuum envelope of the spectrometer be imaged onto the sample support in order to heat the sample. The source may be a laser source but
because of the small size of the sample, it is sufficient and less expensive to image the filament of a bulb onto the sample carrier.
The frequency spectrum of the blackbody radiation is temperature dependent and at the temperature used to pyrolyse samples in a mass spectrometer the main energy falls in the infrared region of the spectrum. It is important to note therefore that the term
"transparent" as used herein is intended to mean transparent to infrared radiation rather than visible radiation.
It is not the total amount of energy emitted in this frequency range that is indicative of temperature but the shape of the frequency spectrum. In the preferred embodiment of the invention, the emitted radiation is incident upon two detectors with different frequency characteristics, the relative outputs of the two detectors providing an indication of the temperature of pyrolysis.
The detectors may be of the same type but their frequency response altered by means of filters having different pass bands arranged in the apth of the incident radiation.
The invention will now be described further, by way of example, with reference to the accompanying drawing which is a schematic representation of apparatus for pyrolysing a sample in mass spectrometer.
In the accompanying drawing, a glass slide 10 carrying a sample 1 2 is urged into sealing engagement with the mouth of the inlet system 1 4 of a mass spectrometer. A suitable inlet system is described in Patent Application
No. 8315956 but a detailed explanation of the operation of the mass spectrometer is not essential to the understanding of the present invention. It suffices to say that the particles resulting from the pyrolysis are formed into an ion beam which passes through a filter capable of discriminating between ions based upon their mass or mass-to-charge ratio. This enables an indication to be given of the atomic masses present and their relative proportions. The particles present are dependent upon the temperature of pyrolysis as this affects the degree to which the sample is broken down.
The slide 10 is formed with a coating of predetermined emissivity on which the sample 1 2 rests. The coating preferably has high emissivity and absorbance and must itself be capable of withstanding high temperature without releasing particles into the vacuum. A suitable material for the coating is oxidised nickel which meets these requirements but other materials such as tungsten may be employed.
In order to heat the sample 12, an image of the filament of a bulb 20 (preferably a tungsten halogen bulb) is formed on the coating on the slide 10, by means of an annular lens 22. The current through the filament of the bulb 20 is variable by a suitable circuit (not illustrated) to allow regulation of the heating.
At the centre of the lens 22, there is provided a concave mirror 24 facing the slide 10 and focussing the blackbody radiation emitted from the coating on the slide onto a split detector 26. The split detector is associated with two filters 28, 30 having differing pass bands. The relative amounts of energy sensed by the two parts of the split detector 26 indicate the temperature of the coating on the slide and hence the pyrolysis temperature. A shield 32 prevents the detector from being affected directly by the energy emitted by the bulb 20.
The glass used in the slide is of importance since some glasses are opaque to infrared.
The use of inexpensive borosicate glass precludes measurement much above wavelengths of 2um but this still permits measurement upto a temperature of 7400"C, which suffices for most applications.
The temperature control circuit typically comprises a first differential amplifier to measure the difference between the output of the split detector 26, the output of the differntial amplifier being representative of the actual temperature. A second differential amplifier may compare the output of the first differential amplifier with a preset voltage representing the desired temperature and produce an error signal which controls the current flowing through the filament of the bulb 20 and thereby alter the energy incident upon the sample.
It is seen in the case of the embodiment described above, the heating and temperature monitoring are performed from the same side of the sample by suitable design of the optical system. This need not necessarily always be the case. For example, if the sample is arranged on a foil disposed within a tube, the bulb 20 and its imaging optics may be arranged on one side of the sample while the detectors may be arranged on the opposite side or at right angles. This configuration reduces the possibility of the detectors being directly affected by the energy emitted by the bulb 20, thereby avoiding the need for the heat shield 32.
Claims (9)
1. A method of pyrolysing a sample for analysis in a mass spectrometer, which comprises providing a transparent window in the vacuum envelope of the mass spectrometer for permitting the sample to be viewed during pyrolysis, heating the sample by a controllable heating source, monitoring the blackbody radiation emitted during the heating to provide an electrical signal indicative of the temperature and controlling the heating source in dependence upon the the sensed temperature in such a manner as to maintain the pyrolysis temperature at a predetermined value.
2. A method as claimed in claim 1, wherin the sample is mounted on a transparent slide or within a transparent tube forming part of the vacuum envelope of the spectrometer.
3. A method as claimed in claim 1 or 2, wherein the sample is supported on a substrate having a coating of predetermined emissivity.
4. A method as claimed in claim 3, wherein the coating is of nickel oxide.
5. A method as claimed in claim 3 or 4, wherein the temperature is measured by monitoring the radiation emitted by a part of the coating not covered by the sample.
6. A method as claimed in any preceding claim, wherein the sample is heated by imaging the energy from a radiant energy source disposed outside the vacuum envelope of the spectrometer onto the sample support.
7. A method a claimed in claim 6, wherein the source is the filament of an incandescent light bulb.
8. A method as claimed in any preceding claim, wherein the emitted blackbody radiation is incident upon two detectors with different frequency characteristics, the relative outputs of the two detectors providing an indication of the temperature of pyrolysis.
9. A method of pyrolysing a sample for analysis in a mass spectrometer, substantially as herein described with reference to and as illustrated in the accomapnying drawing.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08406773A GB2155664A (en) | 1984-03-15 | 1984-03-15 | Pyrolysis mass spectrometer |
PCT/GB1985/000092 WO1985004282A1 (en) | 1984-03-15 | 1985-03-05 | Pyrolysis mass spectrometry |
JP50111485A JPS61501664A (en) | 1984-03-15 | 1985-03-05 | Pyrolysis mass spectrometer |
EP19850901476 EP0177530A1 (en) | 1984-03-15 | 1985-03-05 | Pyrolysis mass spectrometry |
AU40680/85A AU4068085A (en) | 1984-03-15 | 1985-03-05 | Pyrolysis mass spectrometry |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08406773A GB2155664A (en) | 1984-03-15 | 1984-03-15 | Pyrolysis mass spectrometer |
Publications (2)
Publication Number | Publication Date |
---|---|
GB8406773D0 GB8406773D0 (en) | 1984-04-18 |
GB2155664A true GB2155664A (en) | 1985-09-25 |
Family
ID=10558137
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB08406773A Withdrawn GB2155664A (en) | 1984-03-15 | 1984-03-15 | Pyrolysis mass spectrometer |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0177530A1 (en) |
JP (1) | JPS61501664A (en) |
AU (1) | AU4068085A (en) |
GB (1) | GB2155664A (en) |
WO (1) | WO1985004282A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103677012B (en) * | 2013-11-28 | 2016-11-02 | 北京振兴计量测试研究所 | A kind of improve suction surface source black matrix uniformity finely divide control system |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB833570A (en) * | 1957-03-21 | 1960-04-27 | Hilger & Watts Ltd | Spectroscopic analysis |
GB1118303A (en) * | 1964-11-27 | 1968-06-26 | British Iron Steel Research | Heating control system |
GB1222167A (en) * | 1968-12-18 | 1971-02-10 | Inst Metallurgii Imeni Aa Baik | Method and apparatus for controlling colour temperature of an object |
GB1372753A (en) * | 1971-01-11 | 1974-11-06 | Honeywell Inc | Apparatus for processing a workpiece with a laser beam |
GB1395797A (en) * | 1972-06-22 | 1975-05-29 | Royds Jones E M | Apparatus to measure radiant heat |
GB1556829A (en) * | 1975-08-26 | 1979-11-28 | Desmarquest & Cec | Process and plant for fritting ceramic products |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2705308C2 (en) * | 1977-02-09 | 1979-04-19 | Bodenseewerk Perkin-Elmer & Co Gmbh, 7770 Ueberlingen | Device for heating a graphite tube in a graphite tube cell of an atomic absorption spectrometer |
US4198849A (en) * | 1978-03-27 | 1980-04-22 | Hans Siess | Pyrometric temperature measurements in flameless atomic absorption spectroscopy |
JPS56132757A (en) * | 1980-03-19 | 1981-10-17 | Hitachi Ltd | Ion source for mass spectrometer |
DE3221681A1 (en) * | 1982-06-08 | 1983-12-08 | Bayer Ag, 5090 Leverkusen | Mass spectrometer with an external sample holder |
-
1984
- 1984-03-15 GB GB08406773A patent/GB2155664A/en not_active Withdrawn
-
1985
- 1985-03-05 JP JP50111485A patent/JPS61501664A/en active Pending
- 1985-03-05 WO PCT/GB1985/000092 patent/WO1985004282A1/en not_active Application Discontinuation
- 1985-03-05 EP EP19850901476 patent/EP0177530A1/en active Pending
- 1985-03-05 AU AU40680/85A patent/AU4068085A/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB833570A (en) * | 1957-03-21 | 1960-04-27 | Hilger & Watts Ltd | Spectroscopic analysis |
GB1118303A (en) * | 1964-11-27 | 1968-06-26 | British Iron Steel Research | Heating control system |
GB1222167A (en) * | 1968-12-18 | 1971-02-10 | Inst Metallurgii Imeni Aa Baik | Method and apparatus for controlling colour temperature of an object |
GB1372753A (en) * | 1971-01-11 | 1974-11-06 | Honeywell Inc | Apparatus for processing a workpiece with a laser beam |
GB1395797A (en) * | 1972-06-22 | 1975-05-29 | Royds Jones E M | Apparatus to measure radiant heat |
GB1556829A (en) * | 1975-08-26 | 1979-11-28 | Desmarquest & Cec | Process and plant for fritting ceramic products |
Also Published As
Publication number | Publication date |
---|---|
EP0177530A1 (en) | 1986-04-16 |
WO1985004282A1 (en) | 1985-09-26 |
GB8406773D0 (en) | 1984-04-18 |
AU4068085A (en) | 1985-10-11 |
JPS61501664A (en) | 1986-08-07 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |