JPS5838445A - Spark source mass spectrograph - Google Patents

Abstract

PURPOSE:To aim at dispensing with pre-treatment of samples and yet improving analyzing sensitivity, by setting up an ultraviolet-ray radiator part applying ultraviolet rays to a sample electrode, while making spark discharge possible between insulator samples and ionizing the surface of each sample. CONSTITUTION:An ultraviolet-ray generator part 4 is located at the side of an ionization chamber 3 so as to spread out the radiating rays overall a sample 1. In addition, the ulatraviolet-ray generator part 4 is provided with a discharge chamber 5 and an intermediate chamber 6, and this discharge chamber 5 is provided with an inflow part 7 of gas for discharge and an exhaust port 7. To keep up the desired pressure inside the discharge cahmber 5, a needle valve 9 is installed in the inflow port 7. On the other hand, the intermediate chamber 6 is interconnected to the ionization chamber 3 via a circular slit 16 and the ultraviolet-ray generator part 4 is possible to be attached or detached at need, with the ionization chamber 3 and a flange 18. With this, if ultraviolet rays are radiated on the surface of each sample, atomic corpuscles nearby the surfaces are ionized so that pre-treatment of samples is no longer required and spark discharge can be achieved between electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spark source mass spectrometer, and more particularly to a spark source mass spectrometer that irradiates a sample with ultraviolet rays and makes it possible to analyze an insulator sample.

Spark source mass spectrometry is a method in which the sample itself is used as an electrode under high vacuum, a spark discharge is generated between the sample electrodes, and the resulting mass spectrum is analyzed.
It is applied to the analysis of trace impurities in semiconductors, etc.

If the sample is an insulating material such as glass or ceramics, spark discharge will not occur even if the sample itself is used as an electrode.

Therefore, when the sample is an insulator, methods such as crushing the sample and mixing it with carbon powder and forming it into an electrode, vapor depositing metal on the sample surface, or coating the sample with metal foil, etc. This enables spark discharge.

However, the carbon powder, metal deposited film, metal foil, etc. used in these methods often contain impurities. Spark source mass spectrometry allows very highly sensitive analysis, and is greatly influenced by impurities contained in the amount of substances other than these samples. Moreover, the spectrum of these substances themselves may overlap with the spectrum of the target element.

An object of the present invention is to provide a spark source mass spectrometer that enables no-spark discharge of an insulating sample without using any substance other than the sample that causes impurity contamination.

In the present invention, the sample surface is ionized and ionized in order to enable spark discharge between the insulator samples.

The substances that make up glass, ceramics, etc. are in the state of oxides. The dissociation energy for breaking the bond between oxygen and metal atoms is 10 eV or less, and the ionization energy of the dissociated metal atoms is also 10 eV or less. Therefore, if the sample surface is irradiated with light having an energy of 10 eV or more, the surface will be ionized and spark discharge will become possible.

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a side view of the ionization chamber, and FIG. 2 is a sectional view of the vicinity of the ultraviolet ray generating section in FIG.

Attach the insulator sample (1), such as glass or ceramics, to the positive side electrode support (2), attach one high-purity metal wire to the negative side electrode support (2), and place it in the ionization chamber (3). ) and evacuated to 10"5Pa.

The ultraviolet light generating section (4) is arranged on the side of the ionization chamber (3) so that the entire sample (1) is irradiated with the emitted light. The ultraviolet ray generating section includes a discharge chamber (5) and an intermediate chamber (6). The discharge chamber (5) is provided with an inlet (8) for discharging gas and an exhaust port (8) connected to a vacuum pump.
7) is provided with needle pulp (9).

The cathode (10), which is a discharge electrode, is needle-shaped, and the ground electrode αυ opposite to this is a circular flat plate with a hole (12) in the center that serves as an optical path.
). These discharge electrodes are made of insulating material (13), (1
4), supported and fixed by (15). The insulating material (14) forms a cylindrical discharge chamber, and a discharge accompanied by the generation of ultraviolet rays takes place inside this chamber. Therefore,
The electric field applied to the discharge electrode is concentrated at the tip of the needle cathode 00), and the density of the emitted light obtained by glow discharge is extremely high.

The intermediate chamber (6) communicates with the ionization chamber (3) via a circular slit α6). The intermediate chamber (6) is provided to prevent the gas flowing into the discharge chamber (5) from worsening the degree of vacuum in the ion chamber (3), and is connected to a vacuum pump through an exhaust port (17). ing. The ultraviolet generating part (4) can be attached and removed using the ionization chamber (3) and the flange α barrel.

The ultraviolet light emitted in the discharge chamber (5) is irradiated onto the sample (1) through the ground electrode (1υ central hole (I2, slit 06 between the intermediate chamber (6) and the ionization chamber). The energy of the irradiated light can be changed depending on the type of gas flowing into the discharge chamber.The energy that breaks the bonds between oxygen in oxides and other elements in insulators such as glass and ceramics, and ionizes elements other than oxygen. For example, when helium is used as the discharge gas, the energy of the emitted light is about 20 to 23 eV, and when hydrogen is used, it is about 10 to 13 eV. When the object surface is irradiated, atoms near the surface are ionized, so a spark discharge can be generated between the sample and the counter electrode without pretreatment.

The ultraviolet ray generating section may be one in which a sealed discharge tube is placed inside the ionization chamber. In that case, the energy of the emitted light depends on the window material used to extract the light from the discharge tube. For example, if lithium fluoride is used as the window material, the energy of the light that can be extracted is up to about 11 eV, but the glass It is also possible to ionize near the surface of insulators such as ceramics, making spark discharge possible.

According to the present invention, the sample can be prepared by pulverizing the sample, mixing it with conductive powder such as carbon powder, and molding the sample, depositing a conductive substance on the sample surface, or covering the sample with conductive foil. This eliminates the need for pretreatment, and avoids the contamination of contaminants caused by these pretreatments, simplifying the analysis of insulator samples. Furthermore, since the blank value can be lowered, analysis sensitivity can be improved.

[Brief explanation of the drawing]

Figure 1 is a side view of the ionization chamber equipped with an ultraviolet light source.
FIG. 2 is a schematic cross-sectional view of the vicinity of the ultraviolet ray generating portion in FIG. 1.

Claims (1)

[Claims] 1. In a spa p-source mass spectrometer that applies a voltage between a sample electrode and a counter electrode in an ionization chamber to generate ions by spark discharge and measure the resulting mass spectrum, A spark source mass spectrometer characterized by being provided with an ultraviolet generating section that irradiates the sample pole with ultraviolet rays. 2. The spark source mass spectrometer according to claim 1, wherein the ultraviolet light generating section is arranged so that the emitted light irradiates the entire sample pole in the ionization chamber. Spark source mass spectrometer. 3. The spark source mass spectrometer according to claim 1, wherein the ultraviolet light generating section is capable of emitting light having an energy of 10 eV or more.