JPS5913696B2 - Atomic analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an atomic analyzer, and more particularly to a novel atomic analyzer equipped with a light source section that generates an atomic spectrum.

Among recent pollution prevention-related technologies, atomic analyzers have attracted particular attention due to the need for quantitative analysis of minute amounts of harmful metal elements.

Examples of atomic analyzers include atomic absorption spectrometers, atomic fluorescence photometers, atomic absorption spectrometers that utilize the Ze'5-Mann effect, and atomic analyzers that utilize coherent forward scattering.
Conventionally, the light source section for generating the atomic spectrum of these atomic analyzers can be broadly classified into two types. One is a non-polar discharge tube and the other is a polarized discharge tube. Polarized discharge tubes are further divided into counter electrode types and hollow cathode types.
A non-polar discharge tube heats a substance containing a specific element to obtain atomic vapor, and obtains an atomic spectrum by applying high frequency waves to the atomic vapor from a high-frequency coil.

However, since materials containing elements are heated and used, heat resistance is required for discharge tube members, but metal elements with melting points exceeding this heat resistance limit, such as tungsten, titanium, vanadium, It is virtually impossible to produce a polarless discharge tube that can obtain atomic spectra for elements such as silicon. In the opposed electrode type polarized discharge tube, direct current or low frequency power or high frequency power is applied between the discharge electrodes. In this case, although it is possible to obtain an atomic spectrum for a metal element with a high melting point, there is a problem in that the light intensity is low. That is, by applying direct current or low frequency power, atoms of a specific element on the electrode are sputtered and atomized, but the excitation is not sufficiently performed. Further, although it can be excited by applying high-frequency power, fewer atoms are generated by sputtering. For this purpose, some methods apply direct current or low frequency power and high frequency power in a superimposed manner, but it is not possible to sufficiently excite all of the atoms sputtered by the direct current or the like. Therefore, although a certain level of light intensity can be obtained, there is a problem that the electrodes are heavily consumed due to sputtering and their lifespan is shortened.
' A hollow cathode type polarized discharge tube applies a direct current between the hollow cathode and the anode, but it has the problem of a short lifespan.

As described above, all conventional light sources that generate atomic spectra have problems such as low emission intensity or short lifetime.

Among atomic analyzers, especially atomic absorption spectrometers that utilize the Zeeman effect, there are two ways to apply a magnetic field to give the Zeeman effect: one is to apply it to the light source part, and the other is to apply it to the atomization part. .

When a non-polar discharge tube is used as the light source in the method of applying a magnetic field to the light source, stable discharge occurs even in a magnetic field of about 10 kG.

However, as described above, it is virtually impossible to create a non-polar discharge tube that can obtain atomic vectors for high melting point metal elements. Furthermore, when a facing electrode type polarized discharge tube is used, the higher the intensity of the applied magnetic field, the higher the discharge sustaining voltage needs to be.

Here, the discharge sustaining voltage becomes abnormally high in a 10 kG magnetic field. In this way, when the discharge sustaining voltage is high, the acceleration speed of ions for sputtering increases, which increases the amount of sputtering, resulting in faster electrode consumption and extremely shortened lifespan. There is a problem. Incidentally, the discharge sustaining voltage when a 10 kG magnetic field is applied is about five times or more as compared to the discharge sustaining voltage when no normal magnetic field is applied. Next, in the case of a hollow cathode type polarized discharge tube, there is a problem that the discharge is not sustained when a magnetic field is applied.

As described above, there is no suitable light source section for an atomic absorption spectrophotometer that utilizes the Zeeman effect by applying a magnetic field to the light source section.

Therefore, there is a method of applying a magnetic field to the atomization section instead of the light source section.

Originally, a burner-type atomization unit is appropriate from the standpoint of stability, but it is difficult to apply a magnetic field to a burner-type atomization unit, so a graphite cell atomization unit is used. ing. However, the method of applying a magnetic field to the atomization part of a graphite cell has a problem of poor reproducibility. The present invention has been made in view of the above problems, and its purpose is to provide an atomic analyzer with high performance.

According to a preferred embodiment of the present invention, an atomic analysis device utilizing the Zeeman effect with high performance is provided.

In the present invention, one and the other of the electrodes of the light source section of an atomic analyzer are made to have different shapes, and only high-frequency power is applied to the above-mentioned electrode and the other electrode, and a high-frequency discharge is generated between the above-mentioned electrode and the other electrode. It was designed to maintain the An embodiment of the present invention will be described using FIG. 1.

This case is an example of an atomic absorption spectrophotometer that utilizes the Zeeman effect by applying a magnetic field to the light source. First, the light source section 30 will be explained. Noble gas (neon,
The tube body 5, which is filled with about 2T0rr to 10T0rr of (argon, helium, krypton, etc.), has a light extraction window 8 for extracting light. A first electrode 6 and a second electrode 7 are arranged to face each other inside the small diameter portion of the tube body 5. The hollow portion 61 of the first electrode 6 contains an elemental material that generates a desired elemental spectrum. Second
The electrode 7 is ring-shaped. The supply lines 1 and 2 that supply high frequency power from the high frequency power supply 3 each have a first electrode 6,
It is connected to the second electrode 7, and the supply line 2 is grounded. Magnets 9, 1
A magnetic field is formed by 0. The rare gas in the tube body 5 is ionized by the high-frequency discharge, and the ions collide with the inner surface of the hollow portion 61 of the first electrode 6, sputtering the material forming the electrode.

These sputtered atoms are excited by high frequency power and emit light. At this time, since a magnetic field is formed by the magnets 9 and 10, the Zeeman effect occurs and a Zeeman split atomic spectrum is generated. The light passes through the light extraction window of the tube body 5, and the degree of polarization is corrected by the polarization corrector 11. The measurement sample becomes atomic vapor in the atomization section 12. When light passes through the atomic vapor in the atomization section 12, it is absorbed depending on the content of the target element in the sample. The absorbed light is further polarized by a polarizer 13 and detected by a detection unit 14. FIG. 2 shows the relationship between the frequency of high-frequency power applied between the electrodes and the light intensity.

The vertical axis shows the light intensity on a logarithmic scale, and the horizontal axis shows the frequency on a logarithmic scale. At this time, the first electrode 6 is made of cadmium, copper,
Each aluminum electrode is of a hollow type, the inner diameter of the hollow part is 31 tm, and the depth of the hollow part is 10 mm.
The second electrode 7 is made of nickel metal and has a cylindrical shape with a diameter of 8 mT!
The length is L and the height is 3. The first electrode 6 and the second electrode 7 are separated by 5 mm. Inside the tube body 5, 9T0rr of neon is sealed. A magnetic field of 10 KG is formed by magnets 9 and 10. The high frequency power applied between the electrodes was 15W. Here, below 3 MHz, the discharge becomes unstable. That is, a temporal drift of the discharge and a change in the discharge position occur. Also, 300MH2
In the above case, the electrode may be deformed or the discharge may become unstable. Further, the emission intensity at 3Mj or 300MH2 is sufficiently greater than the emission intensity of a hollow cathode type polarized discharge tube to which no magnetic field is applied, and the lifetime is more than three times longer.

FIG. 3 shows the relationship between the high frequency power applied between the electrodes and the light intensity.

The vertical axis shows light intensity on a logarithmic scale, and the horizontal axis shows high frequency power. At this time, the conditions are the same as when obtaining the relationship shown in FIG. 2, but the frequency of the high frequency power is set to 100 MH2.

Here, at 20 W or more, the electrode deforms and deteriorates due to heating, and the life span becomes short.

In addition, atomic vapor generated by sputtering spreads, making it impossible to effectively emit excited light. Further, when the power is 2 W or less, less atomic vapor is generated due to sputtering, and the emission intensity is weak. Furthermore, at about 1 W, sputtering does not occur and although discharge occurs, no light is emitted from the metal element. The emission intensity at 2W is sufficiently greater than the emission intensity of a hollow cathode type polarized discharge tube to which no magnetic field is applied9, and the life span is sufficiently long.

In the examples shown in Figures 2 and 3 above, the other characteristics of the frequency or high-frequency power for the substitute device are clearly shown, but can this representative value be changed? If Tj is set, the tendency remains the same, although there is some change in its absolute value. Next, the fourth
Grounding of the second electrode 7 will be explained with reference to the figure.

FIG. 4 was measured under the same conditions as FIG. 3, and a in FIG. 4 is the same as in FIG. That is, this is the case where the second electrode 7 is grounded. On the other hand, in FIG. 4b, both the first electrode 6 and the second electrode 7 are grounded and the T
Yes. As is clear from the above, the light intensity is higher when the second electrode 7 is grounded. However, let us compare the value of b in FIG. 4 at 20 W with a hollow cathode type polarized discharge tube to which no magnetic field is applied.

The relationship between light intensity and direct current or low frequency power supplied by a hollow cathode type polarized discharge tube shows a relatively steep peak value. The light intensity at the peak value and the light intensity at 20W in b of FIG. 4 are approximately the same value. However, the life in case b of FIG. 4 is longer than that of a hollow cathode type polarized discharge tube, and is more than three times as long. The above explanation describes the case where a magnetic field is applied, but
When no magnetic field is applied, the light intensity and lifetime are further improved.

According to one embodiment of the present invention, the life of the light source section is longer than that of the conventional one. In addition, since the light intensity is high, the S value can be increased, the S/N ratio is improved9, and the accuracy of the atomic analyzer is improved. In addition, since only high frequency discharge is used,
Since the metal elements are less likely to adhere to the inner wall of the tube, the electrodes and the light extraction window can be brought closer together, and the tube can be made smaller. Also,
When a magnetic field is applied to the atomization section, the light intensity is high, so reproducibility is also improved. Furthermore, since a method of applying a magnetic field to the light source section is used, the atomization section can be made into a burner type with good reproducibility, and the accuracy of the atomic absorption spectrometer that uses the Zeeman effect is improved. Furthermore, when applying a magnetic field to the light source section, the tube body can be made small, so a small magnet can be used to effectively apply the magnetic field. Furthermore, since high-frequency discharge is used, there is no need to provide directionality for the electric field and the magnetic field, and the magnetic field can be applied from an optimal direction. In the above description, the second electrode is ring-shaped, but other shapes may be used as long as high-frequency discharge occurs between the second electrode and the first electrode.

Therefore, the second electrode may be outside the tube. That is, it may be an electrode on the outer surface of the tubular body or around it, or it may be a shield electrode when the electrode is also grounded. Further, in the case of a shield electrode, among the supply lines from the high frequency power source, those connected to the second electrode do not need to be grounded and directly connected to the second electrode. In order to have a metal element that emits a unique atomic spectrum in the hollow part of the first electrode, it is possible to make the electrode itself from a sintered alloy, to make the electrode from the metal element itself, or to add a metal element to the hollow part. Various modifications are possible, such as plating or just placing it.

Furthermore, when used as a general atomic absorption spectrophotometer, it goes without saying that a magnet, polarization corrector, or polarizer is not required.

When used as an atomic fluorescence photometer, the direction of light extraction from the atomization section may be changed. According to the present invention, the performance of an atomic analyzer is improved.

Furthermore, if applied to an atomic analyzer that utilizes the Zeeman effect, its performance will be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention.
FIG. 2 is a diagram showing frequency dependence of light intensity according to an embodiment of the present invention, and FIGS. 3 and 4 are diagrams showing high frequency power dependence of light intensity according to an embodiment of the present invention. . Explanation of symbols 3... Power supply, 5... Tube body, 6... First electrode, 7... Second electrode, 8... Light extraction part,
9, 10... Magnet, 12... Atomization part, 13...
Polarizer, 14... detection section, 30... light source section, 61.
... part of holo.

Claims (1)

[Scope of Claims] 1. A light source section that generates an atomic spectrum, an atomization section that atomizes a measurement sample while being irradiated with light from the light source section, and a detection unit that detects the light from the atomization section. The light source section includes a tube body filled with a discharge sustaining gas and having a light extraction window, a first electrode for generating a spectrum disposed in the tube body, and the first electrode. In an atomic analyzer comprising second electrodes having different shapes, and a power source that generates a discharge between the first electrode and the second electrode, the power source connects the first electrode and the second electrode. An atomic analyzer characterized in that only high-frequency power is applied to the electrodes of the atomic analyzer. 2. In claim 1, the high frequency power has a frequency within a range of 3 MHz to 300 MHz,
Moreover, the atomic analyzer is characterized in that the electric power is within the range of 2W to 20W. 3. The atomic analysis device according to claim 1, wherein the second electrode is provided within the tube. 4. The atomic analysis device according to claim 1, wherein the second electrode is grounded. 5. A light source section that generates an atomic spectrum, an atomization section that atomizes the measurement sample while being irradiated with light from the light source section, and a detection section that detects the light from the atomization section, The light source section includes a tube filled with a discharge sustaining gas and having a light extraction window, and is disposed within the tube, and has a hollow section and an elemental substance that generates an elemental spectrum specific to the hollow section. a power source that applies only high-frequency power to the first electrode and the second electrode; means for applying a magnetic field either to a place where atomic vapor generated by electric discharge exists or to the sample atomized by the atomization section, and to apply a magnetic field to either a place where atomic vapor generated by electric discharge exists or to the sample atomized by the atomization section, and to apply a magnetic field to a predetermined plane of polarization of the light from the light source section. An atomic analysis device characterized in that a polarizer for selecting light of is disposed between the light source section and the detection section.