JPS61211949A - Element micro-analysis - Google Patents

Abstract

PURPOSE:To enable to analyze microcomposition with little influence of the difference in the element combining energy on the sample surface, by generating an aberration over the sample surface with a large amount of picked up ion from an instant discharge. CONSTITUTION:After a power supply unit 14 i charged up to a specific charge level and the switch 15 is on, an instant and strong discharge occurs between electrodes 4a and 4b, and the reacted gas is ionized to generate a large amount of primary ions. The primary ions are accelerated by an electrode 5 toward a slit 7 while focused by a magnetic ring 6, and emitted from the slit 7 to a sample 8 as ion beams. On the surface of the sample, there occurs an aberration when receiving the primary ion beams emission, and the ionized sample contents are made into secondary ions, being emitted from its surface. The secondary ions are picked up by a pickup electrode 9, accelerated to a slit 11 while separated according to their different masses in a magnetic field of a magnet ring 10, delivered to a detector 12 one by one, and the mass spectrum is measured by the analysis and recording unit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an elemental microanalysis method, and more particularly to a microanalysis method in which ions are generated by ablation of a sample surface and subjected to mass spectrometry.

[Prior art and its problems]

There are various methods for trace analysis of elements, but the one known to have the highest detection limit is one that generates ions by causing ablation on the sample surface, and ions released from the sample surface. This is a method of mass spectrometry. Conventionally, in this method, a high-frequency discharge is generated between electrodes with a sample placed between them, and the high-frequency discharge causes ablation on the sample surface to release ions of the constituent elements of the sample, which are then transferred to an accelerating Ti pole and a mass separation magnetic field. Detected through However, with this method, due to ablation caused by high-frequency discharge, light elements with low binding energy tend to be released from the sample surface in large quantities, which hinders the accuracy of quantitative analysis and also poses problems with reproducibility. was.

Therefore, an elemental trace analysis method that eliminates the drawbacks of the conventional techniques associated with ablation of the sample surface by high-frequency discharge as described above, causes more complete ablation of the sample, and allows highly accurate quantitative analysis to be performed with good reproducibility. It is an object of the present invention to provide the following.

[Structure and operation of the invention] In order to achieve the above-mentioned problems, in the elemental trace analysis method of the present invention, an instantaneous discharge is caused between opposing electrodes under reduced pressure in a vacuum container to generate more ions, and this primary This method uses ions to cause ablation of the sample surface, and thereby performs sample analysis using secondary ions released from the sample surface.A large amount of ions are generated in a short period of time by instantaneous release of energy between opposing electrodes. By irradiating it onto the sample surface, a sufficiently stable and good ablation occurs on the sample surface, and the reproducibility of this ablation itself is also improved by stabilizing the instantaneous release energy, thereby increasing the precision and reproducibility of quantitative analysis. This achieved improvements in sexual performance.

In the present invention, instantaneous discharge between electrodes can be achieved by, for example, arranging multiple stages of capacitors in parallel and charging them, and then discharging them between opposing electrodes in a vacuum container at a rate of ns (nanoseconds). This is done by flowing a large amount of discharge current in a short period of time to release energy, and for example, a Marx generake can be used for this purpose.

The generation of primary ions due to the instantaneous discharge (for example, H2
, Ho, Ar, N2, etc. are introduced between the electrodes to ionize these reactive gases, or
Another method is to attach a material such as paraffin or an acrylic thin plate containing reactive elements such as H, He, and C to one of the electrodes (cathode), and ionize the reactive elements using the electric field Is theory. In this way, a large amount of ions generated by instantaneous discharge with high energy is irradiated onto the sample surface. In this case, if the sample itself is a material that can constitute an electrode for discharge, one of the opposing electrodes is Alternatively, the sample may be separated from the counter electrode in a vacuum container, and the primary ions may be accelerated and focused to irradiate the sample surface in the form of a beam. .

The sample surface is irradiated with the primary ions to cause ablation, and the secondary ions released from the sample surface are detected by a detector via an accelerating electrode and a mass spectrometry magnetic field to perform mass spectrometry. In this case, the mass spectrometry method itself can be used as is, and the mass difference of the sample before and after measurement and the mass spectrometry results can be combined to perform accurate quantitative analysis. It is something that can be done.

Embodiments of the present invention will be described below with reference to the drawings.

〔Example〕

FIG. 1 is a conceptual diagram showing an example of an apparatus configuration for carrying out the elemental trace analysis method of the present invention.・The exhaust port 2 connected to the reaction gas X for further ion generation (
It has a gas inlet 3 for introducing a certain amount of H2# Hep Arp N2, etc.). Inside the container 1, there are a pair of opposing ? 1
The poles 4a and 4b are arranged, and on the opposite side of the gas inlet 3 across the space between the electrodes, a ring-shaped acceleration electrode 5, a focusing magnet ring 6, and a sleeve 1-7 are arranged in order. Arranged. A sample 8 to be analyzed is placed in front of the slit 7, and is irradiated with an ion beam emitted from the slit 7. Test* using this primary ion beam irradiation! At the top of the sample L18 in the container 1, there is provided an acceleration electrode 9 and a magnetic field generating magnet ring 1° for mass spectrometry, so as to capture secondary ions released from the sample 8 by ablation of the surface of the sample L18. A slit 11 and a test sample 12 such as a Faraday cup are arranged in order, and an external analysis recording device 13 is connected to the detector 12, thereby forming a mass spectrometry system.

In the figure, 14 is a power supply device for instantaneous discharge, and switch 15
It is connected between electrodes 4a and 4b via. This power supply device 14 outputs a high-voltage instantaneous current with a predetermined energy, such as a Marx-Sienerake device that can charge multiple capacitors connected in series in multiple stages in parallel and instantly release the charged charges on the order of nanoseconds. It is something.

Now, in the analyzer with the above configuration, first, the vacuum container 1
The inside is maintained at a predetermined low pressure state by a vacuum pump (not shown), and a predetermined amount of reaction gas (H2p He t A r pN2, etc.) is introduced between the electrodes from the gas inlet 3. When the switch 15 is closed after the power supply unit [14 has been charged up to a predetermined charge level, the electrode 4
An instantaneous strong discharge occurs between a and 4b, and this instantaneous discharge ionizes the reactive gas between the electrodes, producing a large amount of partial ions. These primary ions are accelerated by the electrode 5 toward the slit 7, during which time they are focused by the magnet ring 6, and irradiated from the slit 7 toward the sample 8 as a beam.

On the sample surface irradiated with the primary ion beam, ablation occurs in accordance with the intensity of the beam, and as a result, ionized sample components are generated as secondary ions and emitted from the sample surface.

In this case, the magnitude of the secondary ion release corresponds to the intensity of the ablation, ie the degree of instantaneous discharge between the electrodes 4a, 4b.

The secondary ions released from the sample surface are transferred to the extraction electrode 9
is captured by and accelerated towards the slit 11,
During this time, each mass is separated by the magnetic field of the magnet ring 10 and enters the detector 12+ one after another.
The pawnshop spectrum of relative intensity with ionic current level is measured.

In this case, by separately measuring the mass deviation of the sample 8 before and after the measurement, constant I analysis of the sample components can be performed from the mass spectrum measurement results. .

In the embodiment shown in FIG. 1, the sample material is ionized by ion ablation using the primary ion beam, so by keeping the primary ion beam narrowly focused, it is possible to obtain a trace component analysis image of the solid surface.

In the embodiment shown in FIG. 1, a case has been described in which some of the ions are generated by introducing a reactive gas, but the present invention is not limited to this, and instead of introducing a reactive gas, it is possible to generate some ions on the electrode 4b. H, He of paraffin, acrylic thin plate, etc.
, C, or the like may be attached by coating or adhering, and a portion of the ions may be generated by ionizing this by instantaneous discharge.

In addition, in the present invention, if the sample itself can be configured as an electrode, one of the opposing RI electrodes, for example, the electrode 4b serving as the cathode side.
A part or all of the sample may be configured by the sample, and an example of the device configuration in this case is shown in FIG.

In Fig. 2, the same reference numerals as those in Fig. 1 indicate the same or equivalent parts, and in the vacuum spring mold 1, some of the ion focusing and acceleration systems in the example in Fig. 1 are not provided. , the space between the electrodes 16a, 16b is directly connected to the mass spectrometry system. Counter electrode 16a, 1
Reference numerals 6b correspond to the counter electrodes 4a and 4b in the example shown in FIG. 1, but one electrode 16b is composed of the solid sample itself to be analyzed.

In this example, the reaction gas introduced between the electrodes from the inlet 3 is ionized by an instantaneous discharge between the electrodes 16a and 16b to instantaneously generate a large amount of partial ions, and some of the ions from the discharge are used to electrode the sample electrode. Ablation is caused on the surface of the sample ri to release secondary ions from the surface of the sample ri, which are then transferred to the electrode 9, magnet ring 10. It is captured by Surin 1 bow 1 and made to enter the detector 12, and the analysis recording device 13
mass spectrometry.

In the example shown in FIG. 2, the electrode 15b is made of H2He, C
If the reaction gas contains elements such as the like, it is not necessary to introduce the reaction gas through the inlet 3.

In the example of FIG. 2, the sample electrode 16b has been explained as being entirely composed of the sample 5 itself, but the main structure is the normal electrode 4b, and a part of it may be composed of the sample itself, or the surface of the normal electrode 4b. It may also be one in which a sample substance is coated on the surface of the sample material.

In addition, on each side of FIG. 1 and FIG. 2, the mass spectrometry system after the extraction electrode 9 is not limited to the configuration shown in the drawings, and various quality analyzers including a general vacuum analyzer may be used. It goes without saying that this is possible.

〔Effect of the invention〕

As described above, according to the present invention, since the ablation of the sample surface is caused by a large amount of ions caused by instantaneous discharge, the ablation is not greatly influenced by the difference in the binding energy of the elements on the sample surface. - Quantitative component analysis is possible, and since the ablation intensity is determined by the scale of instantaneous discharge, discharge control provides good reproducibility, and therefore highly accurate quantitative analysis can be achieved.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an example of the configuration of a device F## for carrying out the method of the present invention, and FIG. 2 is a conceptual diagram showing the device configuration according to another embodiment. 1: Vacuum volume W141#4b: Counter electrode, 8: Sample, 9:
Extraction electrode, 10: Magnetic field generating magnet ring for mass spectrometry, 11 Nislit, 12: Detector, 13: Analysis recording device, 14: Power supply device, 15: Switch, 16b: Sample electrode.

Claims (1)

[Claims] 1) Primary ions are generated by instantaneous discharge between opposing electrodes under reduced pressure in a vacuum container, ablation of the sample surface is caused by the primary ions, and the generated sample surface is thereby An elemental trace analysis method characterized by mass spectrometry using secondary ions. 2) The elemental trace analysis method according to claim 1, wherein a quantitative analysis is performed based on the mass spectrometry results by measuring the difference in mass of the sample before and after measurement. 3) The elemental trace analysis method according to claim 1, wherein a predetermined amount of primary ion generating gas such as H_2, He, Ar, N_2, etc. is introduced between the opposing electrodes. 4) The elemental trace analysis method according to claim 1, wherein a material containing a primary ion generating element such as H, He, or C is attached to one of the counter electrodes. 5) The elemental trace analysis method according to claim 1, wherein primary ions are accelerated and focused and irradiated onto the sample surface. 6) The elemental trace analysis method according to claim 1, wherein one of the counter electrodes is constituted by a sample.