JPS58822B2 - Emitter activation device for FD - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for manufacturing ion emitters used in field desorption (FD) ionization mass spectrometers and the like.

As an ion emitter for FD ionization, 10μm
An organic material (mainly benzene) IJ is used on a tungsten wire or a platinum wire with a diameter of φ to 100 μm.

) is used as raw material, expensive (approximately 1000℃) and high electric field (7~10℃).
KV/1 to 2 mm) to generate carbon whiskers with a length of 20 to 50 μm.

The characteristics of the ion source depend on whether the emitter is good or bad, and it is important in FD technology to make a high quality emitter.

Figure 1 shows a conventional FD ion emitter manufacturing apparatus (DF, Barefskyetal, International
t-ionalJ, Mass Spectrometry
&IonPh-ysics14Q97413-14')
.

In the figure, the activation container 5 is first evacuated through the exhaust port 6, and then a gas containing benzonitrile is introduced from the inlet 6' at 10-2 to 1O-3 Torr, and is activated by applying a high electric field and heating the emitter. will be carried out.

Reference numeral 3 denotes an emitter made of tungsten from which whiskers are generated, and a high electric field is applied between it and the counter electrode 2.

Reference numeral 10 denotes an insulator that supports the emitter 3 and also performs vacuum sealing.

In such an apparatus, the conditions for generating whiskers by activating the emitter are determined by the processing temperature, electric field strength, and organic gas pressure, and it is important to control these conditions.

The strength of the electric field is determined by the potential difference applied between the emitter and the opposing electrode and the gap therebetween.

Generally, when a tungsten wire is used as a material for an emitter, the diameter of the material is non-uniform.

Therefore, in order to obtain the same electric field when using a thin tungsten wire and when using a thick tungsten wire,
It becomes necessary to change the potential difference or change the gap.

If the gap is fixed to, for example, 2 mm and the potential difference is made variable, a total potential difference of 15 to 20 KV is required when the tungsten wire is 30 μmφ.

Applying such a high electric field is not preferable because discharge is very likely to occur in other parts.

Therefore, it would be possible to make the gap variable, but this is nearly impossible in the conventional structure shown in FIG. 1 because the gap is determined only after vacuum sealing.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional structure described above, and to provide a device that allows the distance between an emitter and a counter electrode to be easily adjusted and varied with good reproducibility, and that also allows the gap distance to be measured. shall be.

In order to achieve the above object, the present invention includes an emitter moving section composed of a stator having a guide portion and a mover that moves along the guide, a counter electrode, and a counter electrode holder on the same substrate. The counter electrode portion is fixedly arranged on the same substrate.

The present invention will be explained below using examples.

FIG. 2 shows an embodiment of an emitter activation device according to the present invention.

FIG. 3 is a perspective view of the inside of the activation container 20 in FIG. 2.

Benzonitrile gas stored in the holder 8 is introduced into the activation container 20 through the inlet 6' and exhausted through the exhaust port 6, so that the inside of the activation container 20 is always maintained at 10<-3> to 1O<-3> Torr.

The substrate 11 is held in the inner space of the activation container 20 by a substrate holding rod 17 fixed to the lid 21.

For example, a stator 14 with a convex guide is mounted on the substrate 11.
The mover 15 has a concave portion that fits into the convex portion of the stator 14, and is capable of sliding along the convex guide.

The emitter is composed of a stem holder 13, two stems, and an emitter material 22.

A stem holder 13 is attached to the tip of the mover 15 on the opposite electrode 12 side.
is fixed with screws etc.

The stem holder 13 supports two stems 16.

The emitter material 22 is bonded to the two stems 16.

Emitter material 22 is heated by power source 19 through two stems.

The counter electrode 12 is a counter electrode holder 18 made of an insulating material.
The counter electrode holder 18 is fixed to the substrate 11.

When the substrate 11 is made of an insulator, the counter electrode 12 may be attached directly to the substrate 11.

Therefore, the case of only the counter electrode 12 and the case of the counter electrode 12 and the above-mentioned holder 18 are collectively referred to as a counter electrode section.

Further, a high negative voltage is applied to the counter electrode 12 to generate a high electric field between the emitter material 22 and the counter electrode 12.

In the figure, 7 is a hydrogen gas injection port, and 9 is a water reservoir, which are used to treat the surface of the emitter material by repeating oxidation and reduction before forming carbon whiskers on the emitter material.

After carbon whiskers are generated on the emitter material 22 according to the present invention, the emitter is removed from the mover 15 and used as it is as an emitter of a mass spectrometer.

Further, in order to measure the distance between the tip of the stem 16 and the counter electrode 12, a scale is provided on the solid element 14 and the slider 15.

FIG. 4 is a diagram showing an embodiment in which a plurality of emitter materials are attached, in which the slider 15 has a T-shape and a plurality of stem supports 13 are attached to it.

It is also possible to attach each emitter material to a separate movable means so that the position of each emitter material can be adjusted independently.

In order to fix the stem holder 13 to the slider 15, use the holes in the stem holder 13 to fix it with screws, but in order to prevent the stem holder 13 from being contaminated, as shown in FIG. A cover 23 made of Teflon or Micalex is placed over the stem holder 13 and then fixed to the support base.

In FIG. 6, 24 is a modified example of the support base, and the stem holder 1
It also serves as a cover for number 3.

In this way, since the emitter material position is adjusted by the emitter moving section attached to the same substrate as the counter electrode, it can be performed with good reproducibility.

Now, let's talk about the most effective setting method for the emitter material, such as tungsten wire.

These wires have a diameter of 10 to 30 μm and are fixed to the stem by spot welding, but their strength is weak and handling is difficult.

For this reason, it is difficult to reproducibly tension the stem at the center, and this is often done using an appropriate jig.

Therefore, we created a groove in the center of the tip of the stem so that the tungsten wire could be tensioned reproducibly.

Alternatively, a tungsten wire may be plated to the leg of the stem to facilitate spot welding.

An example is shown in FIG.

In the same figure a, a stem holder 76 made of an insulator
A tungsten wire 71 is stretched using a groove 72 provided at the tip of a stem 73 installed as a guide.

The tungsten wire 71 is tensioned and temporarily fixed with appropriate strength using claws 75 on the legs or simple clasps 77 as shown in the figure.

Spot weld this at point A and stop.

When spot welding, use a nickel ribbon or the like as necessary.

In this way, the thin tungsten wire 71 can be easily and reproducibly stretched at the center of the stem 73.

Next, we will describe how to effectively use one emitter heating power source when activating a plurality of emitter materials at the same time.

As mentioned earlier, the processing temperature plays an important role in the generation of whiskers, but when trying to activate multiple emitter materials at the same time, the unevenness of the thickness of the emitter materials makes it difficult to heat one emitter. If activation is performed at once using a power source, the degree of activation will differ depending on the emitter material.

For this purpose, it is preferable to insert a variable resistor for adjusting the emitter current in series or in parallel with each emitter material.

An example is shown in FIG. As shown in FIG. 8a, it is preferable to attach a variable resistor 85 in series with each emitter material 22 to control the amount of current flowing through each emitter material.

In this embodiment, one side of each emitter material is tied together in order to reduce the number of electrodes taken out from the activation chamber.

FIG. 8 shows a modification thereof, in which a variable resistor 85 is placed in parallel with each emitter material 22, and each emitter material 22 is connected in series.

In either case, the current flowing through each emitter material can be fully controlled and the temperature of the emitter material can be adjusted to the appropriate temperature.

Note that the temperature of each emitter material is detected using an optical pyrometer.

As explained above, according to the present invention, it is possible to adjust the distance between the emitter material and the counter electrode with good reproducibility, which is important in the production of emitters for FD.

[Brief explanation of the drawing]

Figure 1 shows a conventional FD emitter manufacturing equipment, Figure 2
3, 4, 5, 6, 7, and 8 are diagrams showing embodiments of the present invention. In the figure, 11 is a substrate, 12 is a counter electrode, 13 is a stem holder, 14 is a stator, 15 is a mover, 17 is a substrate holding rod, and 18 is a counter electrode holder.

Claims (1)

[Claims] 1. An FD ionization process emitter activation device that thermally decomposes an organic gas in a high electric field to form a whisker-like field desorption (hereinafter referred to as FD) ionization emitter on an emitter material. It consists of an emitter moving section for movably attaching the material, and a counter electrode provided on the same base as the emitter moving section, facing the emitter material, and applies a high electric field between the emitter material and the counter electrode. Foot emitter activation device for FD 2, characterized in that the device according to claim 1 is characterized in that the emitter moving section is moved along a stator having a guide and the guide to attach the emitter. 3. The device according to claim 2, characterized in that at least one of the stator and the mover is provided with a scale. Foot mitter activation device for FD