Optics: measuring and testing – By dispersed light spectroscopy – With background radiation comparison
Patent
1994-02-10
1996-12-17
Hantis, K.
Optics: measuring and testing
By dispersed light spectroscopy
With background radiation comparison
G01T 342
Patent
active
055859208
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a device for generating a magnetic field by means of an electromagnet arranged to be periodically switched on and off in order to cause a Zeeman effect for the compensation of the background absorption in an atomic absorption spectrometer
Atomic absorption spectrometers serve to determine the amount or concentration of an element looked for in a sample. For this purpose a measuring light beam from a line emitting light source, a hollow cathode lamp for example, is directed to a photoelectric detector. An atomizing device is arranged in the path of the rays of this measuring light beam. The sample which is to be analyzed is atomized in this atomizing device such that the components of the sample are present in an atomic state. The measuring light beam contains the resonant lines of the element looked for. These resonant lines of the measuring light beam are absorbed by the atoms of the element looked for in the cloud of atoms, while, ideally, the other elements contained in the sample do not influence the measuring light beam. Therefore, the measuring light beam is subjected to an attenuation which is a measure of the number of the atoms looked for in the path of the measuring light beam and thus a measure of the concentration or the amount of the looked for element in the sample, depending on the method of atomization applied. The absorption to which the measuring light beam is subjected is not only caused by the atoms of the element looked for. There is a "background absorption" due to the absorption of the light by molecules, for example. This background absorption has to be compensated for with particularly highly sensitive measurements.
A flame may serve as an atomizing device into which a sample is sprayed as a solution. For highly sensitive measurements the electrothermal atomization is preferably used: The sample is introduced into a furnace which is heated to a high temperature by passing electrical current therethrough. Thereby, the sample is first dried then ashed, and lastly atomized. Then a "cloud of atoms" is generated in the furnace in which cloud the atom looked for is present in an atomic state. The measuring light beam is passed through this furnace. These furnaces can have different shapes. They are conventionally made of graphite.
The Zeeman effect is used for background compensation. When a magnetic field is applied to the absorbing atoms in the atomized sample, splitting and shifting of the resonant lines of these atoms is effected. Then the resonant lines of the atoms no longer coincide with the spectral lines of the measuring light beam and no atomic absorption takes place in the borderline case. This permits discrimination between non-atomic background absorption which is also present when the magnetic field is applied, and real atomic absorption which is superimposed onto the background absorption when the magnetic field is not applied.
This requires that an electromagnet in an atomic absorption spectrometer is alternately switched on and off in order to be able to measure the atomic absorption with the Zeeman effect and without the Zeeman effect. The invention relates to a device which achieves this.
BACKGROUND ART
From German patent application 1,964,469 (U.S. Pat. No. 3,676,004) an atomic absorption spectrometer is known wherein the radiation originates from a single light source designed as a line emitter, the radiation of which passing through the sample is frequency modulated by use of the longitudinal Zeeman effect. In this prior atomic absorption spectrometer a hollow cathode lamp is arranged between the pole pieces of an electromagnet. One of the pole pieces has a bore through which the measuring light beam passes. Then the measuring light beam is directed through a flame serving as an atomizing device and a monochromator and impinges upon a photoelectric detector. The electromagnet is arranged to be switched on and off, whereby the atomic absorption of the sample atoms compensated for with respect to the background absorption c
REFERENCES:
patent: 3676004 (1972-07-01), Prugger et al.
patent: 4204240 (1980-05-01), Schmoock
patent: 4341470 (1982-07-01), Parker et al.
patent: 4365288 (1982-12-01), Robe et al.
patent: 4632549 (1986-12-01), Czabaffy et al.
Smith, "DC Supplies from AC Sources", Wireless World, vol. 90, No. 1583, Sep. 1989, pp. 25-29.
Keuter et al, "Schaltugen . . . Bavelementen", Elektrotechnische Zeitschrift, E.T.Z., vol. 107, No. 5, pp. 200-202, 204, 206, 207.
Roedel Gunther
Rogasch Klaus P.
Aker David
Bodenseewerk Perkin-Elmer GmbH
Grimes Edwin T.
Hantis K.
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