JPS5871547A - Ion source - Google Patents

Abstract

PURPOSE:To accelerate ions in two steps together with an ion gun part and obtain an ion source capable of feeding out neutral particles having extremely high velocity by impressing ion accelerating voltage on a collision chamber while insulating said collision chamber from surroundings in a mass spectrograph. CONSTITUTION:Ar required for an ion gun (10<-2>-10<-4>Torr in pressure) is supplied from a collision chamber (equally 10<-2>-10<-3>Torr). Ar ion formed in a formation chamber 6 inside of the ion gun is accelerated by annular lens electrodes 9, 10 and 11 and then incided into the collision chamber 19, while in this invention said collision chamber 19 is held insulatedly to impress acceleration voltage upon said collision chamber so as to further accelerate Ar ions also between the ion gun and the collision chamber 19 so that energy of ions inciding into the collision chamber 19 is extremely increased as compared with the past wherein ions ucould not be except by the ion gun.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ion source suitable for use in a mass spectrometer,
In particular, it relates to ion sources that ionize samples by colliding high-speed neutral particles with them.The ionization methods of ion sources used in mass spectrometers include electron impact type, chemical ionization type, electric field IwI type, and field desorption type. etc. are being developed and put into practical use one after another. By the way, recently, an ionization method that collides high-energy high-speed neutral particles (such as particles) with a sample and ionizes the sample with that energy has been attracting attention. It is a small and soft ionization. (2) The generation rate of not only positive ions but also negative ions is high. (8) 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. This method has many excellent features and is expected to be developed in the future.

The present invention relates to an improvement of an ion source based on this method. When introducing ions generated from an ion gun into a collision box and converting them into neutral particles, the collision box is insulated from the surroundings and ions are transferred to the collision box. The overall purpose of this invention is to provide an ion source that can accelerate ions together with the ion gun section in two stages by applying an accelerating voltage and extract neutral particles with extremely high velocity. The present invention will be explained in detail below with reference to the drawings.

d#J is a sectional view showing the configuration of an embodiment of the present invention,
In the figure, 1 is an ion gun for ionizing neutral particles such as red atoms to -H to irradiate the sample.The ion gun 1 is attached to the side wall 2 of the ion source of the mass spectrometer, and its interior is exhausted. A node 7 and a filament 8 are evacuated by a vacuum pump (not shown) via a tube 6 and a tube 4.
and a three-stage annular lens electrode ff19, 10.11 attached to the lower end of the cylindrical electrode 5. #
The electrodes 9 and 11 are given a grounding potential, and the electrode 10 is given a positive potential of several Kv by the power source 12, and the positively charged Ar ions (Mu r ) generated in the generation chamber 6 are The ion beam is accelerated and focused by the electric field formed between the electrodes, and is taken out of the ion gun as a high-speed Ar ion beam 16.

Here, the annular electrode 11 is divided into three parts as shown in FIG. 2, which is a cross-sectional view of FIG.
Ar ion beam 16 by applying a positive or negative variable potential of up to several hundred volts to! The direction can be oriented, and the split side 1
1'' can be deflected in the Y direction by applying a similar variable potential.

Note that S5 is a power supply for heating the filament, 16 is a power supply for applying a voltage of several hundred V between the filament anodes, and 1
Reference numeral 7 designates a power source for applying ζg~# to reverse electrons generated from the filament toward the electrode 5 toward the anode, and 67 represents a power source for applying an accelerating voltage.

The high-speed red ion beam 13 taken out from the ion gun 1 in this manner passes through a collision box 19 fixed to the ion source side wall 2 via an insulator 18 and is introduced into the ion source. A negative high voltage is applied from a power source 20 to (1), and the Ar ion beam 13 is accelerated to a higher speed by the high voltage and enters the collision box 19. Ar gas (neutral A) is introduced into the collision box 19 through an introduction pipe 21.
A large portion of the ions passing through the collision chamber collide with these atoms, taking away only their charge without changing their direction or velocity. Because the beam is converted into a neutral Ar atom, Ar ions and neutral Ar atoms coexist in the beam that passes through the collision box 19t. After being deflected and removed, only the neutral Mur atoms pass through the deflector 221'' and are extracted as a high-speed Mur atomic beam 26. In this embodiment, the deflection 62
By grounding the electrode of the pair of electrodes 2 with which the deflected Ar ions collide through the ammeter 24, the
The r-ion current is monitored. Furthermore, since there is a proportional relationship between the Ar ion current and the amount of neutral Mur atoms, the amount of neutral Mur atoms can also be monitored indirectly.

The high-speed Ar [child beam 23
is introduced into the ionization box 26 through the notch 25,
Target 2 inserted into the ionization box 26 from the rear
The atomic beam 25 of No. 7 collides with an inclined target surface, and ionizes a sample prepared by mixing glycerin and a test substance coated on the collision surface. The target 27 is made of steel, for example, and is attached to the tip of the introduction probe 29 via an insulator 28, and an accelerating voltage of, for example, about 3 KV is applied from a power source 30, and the sample ions ejected from the surface are separated by the accelerating voltage. Appropriate voltages obtained by dividing the voltage with the voltage generator 31 are drawn out by the slit electrode groups 52 to 65 to which they are respectively applied, accelerated, and guided to a mass spectrometer (not shown). Note that 36 is a power source for applying a bias voltage (positive or negative f) between the target 27 and the ionization box 26.

In such a configuration, the Ar required for the ion gun 1 (10-" to 10-'τorr in terms of pressure) is
10-” to 10” Torr), and the size of the beam passage port connecting the two and the t of valve 4
The settings are such that each pressure is maintained by section A. The Ar ions generated in the generation chamber 6 in the ion gun 1 are accelerated by the annular lens electrodes 9, 10, 11 and then enter the collision box 9. In the present invention, the collision box 19 is Since an accelerating voltage is applied to the cod collision box while holding the ion gun at The energy of ions incident on the box 19 can be dramatically increased. Therefore, the collision box 19
The energy of the neutral Mur atoms extracted from the sample is increased accordingly, allowing high-speed Mur atoms with large energy to collide with the sample.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention.
FIG. 112 is a cross-sectional view of the same. 1: Ion gun, 6: Ion generation chamber, 9, 10° 11: Annular lens electrode, 20: Power supply, 13: Mur ion beam,
18: Insulator, 19: Collision box, 25: Bulk zr atomic beam, 26: Ionization box, 27: Target. Patent applicant JEOL Ltd. Representative Tadao Kase

Claims (1)

[Claims] It is equipped with an ion gun and a collision box which has a passage through which the t-ions taken out from the cod ion gun pass and uses a collision gas contained therein to remove electric charges from the ions and deform them into neutral particles. An ion source that ionizes a sample by irradiating it onto the sample, characterized in that an accelerating voltage is applied to the collision box to further accelerate the ions taken out from the ion gun.