JPS5864745A - Ion source - Google Patents

Abstract

PURPOSE:To enable ions to be efficiently taken out with a simple constitution of installing auxiliary electrodes by locating the auxiliary electrodes near the surface of a target against which neutral particles collide, and applying an electric potential different from that of the target to said auxiliary electrodes. CONSTITUTION:A high-speed Ar atom beam 10 produced in a neutral particle source 1 used for producing a neutral particle beam such as an Ar atom beam, after being introduced into an ionization box 12 through a cut part 11, bumps against a target surface which is made oblique to the atom beam 10; the target 13 is inserted into above box from the back of above box. The target 13 is attached to the end of an introduction probe 15 through an insulating body 14. An acceleration voltage (Va) is applied to the target 13 from an accelerating power source 16. On the other hand, a slit electrode group 20-23 used for drawing out and accelerating ions produced from the target 13 is installed, and appropriate voltages given by dividing the acceleration voltage (Va) with a voltage divider 24 are made to be applied to the electrodes 20-23.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion source 1ζ suitable for use in a mass spectrometer, and particularly to an ion source I that is inverted by colliding high-speed neutral particles with a sample.

As the ionization method of the ion source used in mass spectrometers, electron impact type, chemical ionization type, field ionization type, and field desorption type have been successively developed and put into practical use. Recent sample I [fast neutral particles with high energy (
A new ionization method has been proposed in which the sample is ionized by colliding with Ar atoms (for example, Ar atoms) and the resulting energy is used to ionize the sample.
1) The energy range of ionization is large. f2) Only positive ions (high generation rate of negative ions); (3) No thermal decomposition of the sample as no heating vaporization is required; (4) Since the particles are neutral, there is no charge-up and even insulating materials can be easily ionized. It has many excellent features and is expected to continue to develop in the future.

The present invention relates to the improvement of the ion source Jζ based on this proposed method 1ζ, in which an auxiliary electrode is arranged near the neutral particle collision surface of the target and a potential different from that of the target is applied to the neutral particle. It has this feature that allows ions to efficiently pass through the extraction slit and be extracted.

The present invention will be explained in detail below using the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention, and 1 is a neutral particle source for generating a neutral particle beam, for example, a mu1 atomic beam. The particle source is a filament 2. A high-velocity Ar ion beam 7 taken out from the cod ion gun 6 is collided with an Ar ion gun 6 equipped with a cathode 3, a γ node 4, and an Il5, and the velocity is t. Neutralize by removing only the charge from the ion until A
It consists of a collision chamber 8 for scraping r atoms, and a deflector 9 for deflecting and removing Ar ions mixed in the high-speed atomic beam exiting the electrostatic collision chamber.

The high-speed Ar atomic beam 10 generated in the neutral particle source 11 is introduced into the ionization box 12 through the notch 11, and the atomic beam 10+ of the target 15 inserted from the rear into the ionization box is An inclination is given to the target surface so that the target surface collides with the target surface.

The target 16 is made of copper, for example, and the tip of the introduction probe 15 is attached to it through an insulator 14, and an accelerating voltage va of about 'TI' is applied from an accelerating power source 16 to the target 5, for example. Set and silent target 13 and ionization box 12
Between 0 and 0, a variable output positive power supply 17 or negative power supply 18 is selectively connected by a switch 19. Reference numerals 20 to 26 represent a group of slit electrodes for extracting and accelerating ions generated from the target 16, and appropriate voltages obtained by dividing the acceleration voltage by a voltage divider 24 are applied to each group.

In this configuration, Ar ions ionized in the ion gun 6I and accelerated at high speed with a high voltage of several KV collide with the gas (Ar atoms) in the collision chamber 8, releasing only electric charge. A high-velocity mu1 atomic beam is converted into a beam.

The high-speed Ar atomic beam 1 taken out from the collision chamber 8
0 travels approximately parallel Jζ to the slit electrode groups 21 to 26 and collides with a target surface that is inclined at an angle of about 20'' to 456 with respect to the direction of travel. A sample prepared by mixing glycerin and a test substance is coated, and the test substance is ionized and ejected from the surface due to collisions with high-speed Ar atoms.
The ions thus generated are extracted by the slit electrode group lζ, accelerated, and guided to the mass spectrometer. At this time, the inventor raises or lowers the potential of the ionization box 12 by several V to several 107 points relative to the target iAt. In particular, it has been found that the amount of ions that can be taken out through the slit electrode can be increased by an order of magnitude. This is presumed to be due to the following reasons.

In other words, the surface of the sample coated on the target surface may be a smooth flat surface, but it may have a complex shape with uneven surfaces or uneven surfaces, so ions generated from the surface may be directed in a specific direction or in many other directions. IC such that direction 1ζ of is small
Having direction often happens. Also, ions may be generated with strong directionality due to the positional relationship between the atomic beam irradiation point and the slit and other reasons. The direction in which many of these ions are generated is as shown in Figure 2 (a) lζ -ζ
There is no problem if it is in the direction of the slit, but in reality, this is rarely the case, and the amount of the material that can be removed from the slit and removed from the slit is extremely small. Most of the time. Therefore, by varying the potential of the ionization box 12 by several volts to several tens of volts with respect to the target potential, a gap between the ionization box and the target in the direction perpendicular to the ion extraction direction -ζ (direction of arrow E) '#Lrf- A large amount of ions can be taken out by generating the electric field and bending the direction in the direction of the slit in the direction of the slit.

In this case, it is thought that the main factor involved in the deflection of ions is the electric field formed between the inclined target surface and the part of the ionization box facing the target surface. , Figure 2 (In the case of BL, the positive ions generated from the target are deflected downward by connecting the positive power supply 17t to make the potential of the ionization box 12 higher than the target potential, and in the case of tel in the same figure, It is necessary to connect an inverse 1 negative power source 18t to deflect the positive ions generated from the target upward.

In this way, since it is the part of the ionization box facing the target surface that is involved in the fly direction, in the case where there is no ionization box, this is the case when the target surface is near or far from the target surface. The auxiliary electrodes may be arranged to face each other so that the auxiliary electrode q7AI can be given a potential different from that of the target.

In the above-mentioned embodiment, the atomic beam irradiation generates t.
Although we tried to extract positive ions among the ions, it goes without saying that negative ions can also be extracted in exactly the same way by simply considering the polarity of the voltage supplied to each electrode.

As detailed above, according to the present invention, ions can be extracted efficiently with a simple configuration in which auxiliary electrodes are arranged. Further, in the actual example shown in FIG. 1, an ionization box is used as an auxiliary electrode, so the structure of the holding weight ζ is simplified.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of one example of the ceramic according to the present invention, and the second
The figure is a diagram for explaining the directionality of ions. 1: Neutral particle source, 2: Filament, 3: Cathode, 4
Near node, 5: Electrode, 6: Mu, ion gun, 7: Mu1 ion beam, 8: Collision chamber, 9: II direction device, 10: High speed Mu1 atomic beam, 11: Notch 1% 12: Ionization box,
13: target, 14: insulator, 16: acceleration power supply, 1
7: Positive power supply, 18: Negative power supply, 19: Switch, 20-2
5 Nisrit electrode. Ar force gate 1 [ '' I engineering 1 [ 2=ko 199-zO 20

Claims (1)

[Scope of Claims] An ion source in which neutral particles applied at a high velocity di collide with a sample held at L target 1 ζ to ionize the sample, and the generated ions are taken out and accelerated through an extraction slit. An ion source characterized in that an auxiliary electrode (4Iit) is disposed near a neutral particle collision surface of a target, and the electrode (1ζ) is configured to apply a potential different from that of the target. λ Ionization box f that accommodates the target: 1Ill
The ion source according to claim 1, which is used as the auxiliary electrode.