JPS5871550A - Ion source - Google Patents

Abstract

PURPOSE:To make it possible to change the course of a neutral particle beam and make correct aligning of position in a short time required by arranging an ion deflection means between an ion gun and a collision chamber to deflect an ion beam, concerning an ion source suitable for a mass spectrograph. CONSTITUTION:A beam passage route (b) on the exit side of a collision chamber 19 is made to be a smaller hole than (a) so that pressure difference from the inside of an ion source of high vacuum (not exceeding 10<-5>Torr) may be maintained. And Ar ions formed in a formation chamber 6 of an ion gun 1 and accelerated by annular lens electrodes 9, 10, and 11 to be converted into a neutral Ar atom beam after passing through the collision chamber 19. In this example of design, the lens electrode 11 serves as well an X-Y detector as shown in illustration so as to be able to deflect an ion beam 13 into an optional direction and accordingly a course of the neutral Ar atom beam 23b converted by passing through the collision chamber 19 is to be optionally changed.

Description

[Detailed description of the invention] This @Beak relates to an ion source suitable for use in a mass spectrometer,
In particular, it concerns an ion source that ionizes a sample by colliding with highly neutral particles.Ionization methods for ion sources used in mass spectrometers include electron impact, chemical ionization, electric field ionization, and electric field desorption. have been developed and put into practical use one after another.Recently, an ionization method that collides high-energy high-speed neutral particles (e.g., Mur atoms) with a sample, and ionizes the sample by increasing the energy by 1, has recently attracted attention. This method is (1) a soft ionization method with low ionization energy; (2) The production rate of not only positive ions but also member ions is high. (3) There is little thermal decomposition of the sample because heating vaporization is not required. (4) Since it is a neutral particle, there is no charge-up and even insulating materials can be easily ionized. It is expected to be developed in the future as a method with many excellent points such as.

However, in this type of ion source, the sample is irradiated with neutral particles that cannot be deflected, so the irradiation position of the neutral particles must be aligned with the sample by mechanical movement of the sample. Not only does this require a complicated precision fine movement mechanism, but it also takes time and effort to align the positions.

The present invention has been made in view of this point, and focuses on the structure of an ion source in which a high-speed ion beam produced by an ion gun is converted into a neutral particle beam in a collision box. The present invention will be explained in detail using the box shown below.O1 box is a configuration of one embodiment of the present invention. In the figure, 1 is an ion gun for temporarily ionizing neutral particles such as Ar atoms that are irradiated onto the sample #c.
is attached to the ion source side wall 21 of the mass spectrometer, and its interior is evacuated by a vacuum pump (not shown) via an exhaust pipe 6 and/or tube 4 [the ion gun 1 has a cylindrical electrode 5 , a node 7 and a filament 8 disposed in the ion generation chamber 6 formed inside the cylindrical electrode 5 , and a three-stage annular lens electrode 9 , 10 . attached to the lower end of the cylindrical electrode 5 . It consists of 11 parts. The electrode 9. IIK is the ground potential, and the electrode 10 is connected to the power source 12.
A positive potential of several KV is applied to the generation chamber 6.
The generated positively charged ions (Ar+) are taken out of the ion gun as an Ar ion beam 16 which is accelerated by the electric field I formed between these electrodes.

Here, one annular electrode 11 is connected to the I-I section I at 6ζ in FIG.
As shown in FIG.
By applying a positive or variable potential up to 6V to 1, the Ar ion beam 16 can be deflected in the X direction, and can also be split (
&11'' should be given a similar variable potential!The structure is such that it can be deflected in the Y direction.

15 is a power source for heating the filament, 16 is a power source for applying a voltage of several 6 volts between the filament and one node,
17 is @'@'6 in order to reverse the electrons generated from the filament toward the electrode 5 toward one node.
c'? A power source 67 is a power source for applying an accelerating voltage.0 The high-speed Ar ion beam 15 taken out from the ion gun 1 in this way is an ion source @@2.
The ion beam is introduced into the ion source through a collision beam 119 fixed via an insulator 18, but a high voltage is applied to the collision beam 19 from a power source 20, and the ion beam is 15 is further accelerated to a higher speed by the cough high voltage and enters the collision box 19. A large portion of the ions passing through the collision chamber collide with the atoms, removing only their charge and converting the high-speed neutral atoms into atoms, with their direction and velocity remaining almost unchanged. As a result, the beam that has passed through the collision box 19 contains a mixture of atoms, including ions and neutral atoms.
The ions are deflected by a subsequent deflector 22#c and removed, and only neutral Ar atoms pass through the deflector 22 and are extracted as a high-speed Ar atomic beam 2s. At this time, of the pair of electrodes of the deflector 22, the electrode with which the deflected Mr ions collide is grounded via the current needle 24, so that the Mr ion current is monitored. Furthermore, since there is a proportional relationship between the ion current and the amount of neutral atoms, the amount of neutral Ar atoms can also be indirectly monitored.

High-speed Ar atomic beam 26 taken out from the 1-direction deflector 22
is introduced into the ionization box 26 through the notch 25,
Turded 2 inserted from the rear into the scissors ionization box 26
The atomic beam 26 of No. 7 collides with a tilted target surface, and the sample prepared by mixing glycerin and the test substance coated with the collision @lζ is ionized. The scissors tarded 27 is made of steel, for example, and is attached to the tip of the introduction probe 29 via an insulator 2B, and an accelerating voltage of, for example, 3 KV is applied from a power source 3o, and the sample ions ejected from its surface are Voltage divider 61 for accelerating voltage
Appropriate voltages obtained by dividing the voltage are drawn out and accelerated by the slit electrode groups 62 to 65 to which they are applied, respectively, and guided to a mass spectrometer (not shown). Furthermore, 66 is Tarded 27
This is a power supply for applying a JC bias voltage (positive, *variable) between the ionization box 26 and the ionization box 26.

In such a configuration, the required torque (pressure: 10 ``wlo' Torr) of the ion gun 11ζ is supplied from the collision box (same (1 G'' to 1 G'' Torr), and the size of the beam passage opening connecting the two is The exit beam passage openings of the zero and center box 19 are set to maintain their respective pressures by adjusting the vacuum valves 4 and 4.
The hole is smaller than 4 cm to maintain a pressure difference between the inside of the ion source (below Q'Torr) and the ion generated by generation #16 in the ion gun 1 is connected to the annular lens electrode 9, 10. After being accelerated by Ilfζ, it passes through the collision box 19 and is converted into a neutral atomic beam. In this embodiment, the lens electrode 11 also serves as an X-Y deflector, as shown in Figure 5112. Ion beam 1 because there is
& can be deflected in any direction, and accordingly, the neutral Ar atomic beam 26 that passes through the collision box 19 and is converted will also be deflected in any direction #C. Therefore, the alignment of the irradiation position of the atomic beam 26 onto the sample can be electrically controlled, making it possible to achieve accurate alignment in a shorter time than in the past, in which the sample was moved mechanically. can.

The beam passage opening of the collision box 19 is mainly aligned in the direction of arrow C in Fig. In order to maintain the pressure difference of 7, it is preferable to make the hole long in the C direction.

In the embodiment in which the lens electrode 11 of the ion gun 1 is divided and used as a deflector by applying a deflection voltage, the present invention is not limited to this, and an independent deflector may be provided between the ion gun and the collision box. Needless to say, an electromagnetic lug may be used as a deflector.

[Brief explanation of drawings]

Part tg is a diagram showing the configuration of an embodiment of the present invention, and ga
s is that! -■1 It is a cutaway diagram. 1: Ion gun, 9, 10.11: Annular lens electrode, N
, 11: split electrode, 15: Ar ion beam 11
9: Collision box, 22: Deflector, 26: High-speed atomic beam, 27: Target.

Claims (1)

[Scope of Claims] L A means for accelerating ions generated by direct ion generation and scissors generation, and a means for accelerating ions generated by scissors generation, and a means for accelerating the ions generated by the scissors generation, and a means for accelerating the ions through which the accelerated ions pass through, and by a collision gas contained within the ions. In an ion source that is equipped with a collision box that removes electric charge and converts it into neutral particles, and that ionizes the sample by injecting the neutral particles into the sample SC@, there is a relationship between the An ion source characterized by being provided with a deflection means for deflecting ions and an ion source according to claim 5, characterized in that an electrode for accelerating ions also serves as a deflection means.