JPS58172854A - Flying time ion mass spectrograph - Google Patents

Abstract

PURPOSE:To improve the sensibility and resolution, by providing an ion accelerator and a plurality of energy analyzing means where the analyzing means is constructed with an outer cylindrical electrode and an inner cylindrical electrode while providing an electrode for passing ion through an ion incident hole during predetermined time width. CONSTITUTION:An ion accelerating step A and an energy analyzing steps B1- B5 are constructed with an inner cylindrical electrode 1 and an outer cylindrical electrode 2 arranged coaxially. The electrode 1 is provided with a circular inlet slit 3 and a circular outlet slit 4 while an incident hole 6 provided with a timing electrode 5 is provided at the inlet end C1 of the initial analyzing step B1 and an outlet hole 7 is made at the exit end D5 of the final analyzing step B5. The accelerating step (A) is coupled through an ion inlet hole 10 to an ion generating source 9 connected with the exhaust system 8. An ion detector 11 is arranged at the rear of said hole 7 and coupled with the exhaust system 12. The detector 11 connected with the power source is connected through an amplifier 14 with an oscillograph. A timing pulse generator 16 is connected with the electrode 5 and the oscillograph 15, to analyze with high sensibility and resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mass spectrometer that analyzes ion mass, and particularly relates to a time-of-flight ion mass spectrometer that differentially analyzes ion mass using the difference in opening during flight of energized ions. This relates to a mass spectrometer.

The principle of the conventional time-of-flight ion mass spectrometer was developed by Double C. Wiley and I.H. McLaren.・Nuku・
Instruments (Rev, Sci, In5t
r,, Vol. 26, No. 12, pp. 1150-1157, 1
955) 1←: It is said.

In other words, in conventional devices, ions do not follow a deflected trajectory, but instead follow a straight flight trajectory from the ion acceleration chamber to reach the ion detector.If the flight distance is increased to obtain high resolution, the detection As the solid angle of the incident ions decreases in inverse proportion to the square of the flight distance,
There is a problem, α, in which the ion detection signal decreases. Furthermore, since the initial energies of the ions cannot be made uniform, there is a problem in that the distribution of this initial energy directly affects the resolution, which has the disadvantage that high sensitivity and high resolution cannot be obtained.

Therefore, although open-in-flight ion mass spectrometers have short analysis times and are useful for analyzing temporally varying ion densities, they are not as effective as quadrupole ion mass spectrometers. Therefore, it was not widely applicable.

An object of the present invention is to eliminate the above-mentioned drawbacks of conventional time-of-flight ion mass spectrometers and to provide a time-of-flight ion mass spectrometer with high sensitivity and high resolution.

Therefore, the time-of-flight ion mass spectrometer of the present invention
An ion accelerating means, an entrance hole through which ions accelerated by the accelerating means pass, and a plurality of energy analysis stages for analyzing energy by emitting and focusing the ions accelerated by the accelerating means at a required angle. , an exit hole disposed at the final stage of the energy analysis stage, and ion detection means for detecting ions passing through the exit hole,
The energy analysis stage has an outer cylindrical electrode that acts as an outer pole of the energy analysis stage and an inner cylindrical electrode that is disposed on the axis of the outer cylindrical electrode and acts as an inner pole of the energy analysis stage. configured, the inner cylindrical electrode comprising:
an entrance slit that allows ions that have passed on the axis at the entrance end of the energy analysis stage to pass through to the external cylindrical electrode side by a reflected potential applied to the internal cylindrical electrode and the external cylindrical electrode; an exit slit opened on a trajectory that reflects the ions by the external cylindrical electrode and focuses the ions at the exit end of the energy analysis stage, and allows ions to pass through the entrance hole for a required time width. It is characterized by the provision of timing electrodes.

The energy analysis stage using coaxial cylindrical electrodes used in the present invention is E.
It is similar to the one devised for the purpose of obtaining the electron energy spectrum by
Volume 147.

228-240, 1957).

According to the gist of the present invention, in which such an energy analysis stage is employed in the flight trajectory of a time-of-flight ion mass spectrometer, since it has a secondary focusing arrangement that allows ions to draw a deflection trajectory using reflected potential, The reason is that the ions are focused at a large solid angle at the time of incidence, and that the ions can be detected without losing the solid angle even if the flight time is long, and that only ions with the same initial energy form a trajectory that reaches the exit hole. This method has the advantage that high sensitivity and high resolution can be obtained because the only ions that can be detected are those with the same initial energy.

Furthermore, the relative mass number (
ratio of mass number of ions analyzed to mass difference resolved)
Since is approximately equal to the ratio of the total length of the energy analysis stage to the distance between the timing electrodes, it also has the advantage that by miniaturizing the timing electrodes, it is possible to create compact ion mass spectrometers with large relative mass numbers. .

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

The figures show a time-of-flight ion mass spectrometer as an embodiment of the present invention. Fig. 1 is a schematic diagram of the device connected to its ion source and its output is displayed on an oscilloscope, and Fig. 2 3 is an explanatory diagram showing the detailed structure of the timing electrode and drive circuit, FIG. 3 is a schematic diagram showing the main parts thereof, and FIGS. 4 to 6 are graphs for explaining the operation thereof.

In FIG. 1, the configuration and arrangement are shown as follows: ion acceleration stage A and energy analysis stages B1 to B5 connected thereto.
The five stages consist of an inner cylindrical electrode 1 and an outer cylindrical electrode 2 arranged coaxially, and the inner cylindrical electrode 1 is provided with a circular inlet slit 3 and a circular outlet slit 4, and the inlet of the first stage B1 of the energy analysis stage is An entrance hole 6 with a timing electrode 5 is provided at the end C1, and an exit hole 7 is provided at the exit end D5 of the final stage B5.

Note that the outlet end D1 of the energy analysis stage B1 and the inlet end C2 of the next energy analysis stage B2 are at the same position, and this relationship is maintained sequentially in each of the energy analysis stages 81 to B5.

The ion acceleration stage A includes an ion generation source 9 connected to an exhaust system 8.
The ion intake hole 10 is connected to the ion intake hole 10.

An ion detector 11 is disposed after the exit hole 7 of the final stage B5 of the energy analysis stage, and the five stages of the ion acceleration stage A, the energy analysis stages B1 to B5, and the ion detector 11 are all connected to the exhaust system 12.

Ion detector 1 connected to ion detector application power source 13
1 is connected to an oscilloscope 15 via an amplifier 14.

Timing pulse generator 16 is connected to timing electrode plate 5 and oscilloscope 15 .

In FIG. 1, to explain the operation, the timing electrode 5
Due to the action of the entrance hole 6, the energy analysis stages B1 to B5
The entering ions (positive ions in this case) have a secondary focused ion trajectory 18 passing through the circular entrance slit 3 and the circular exit slit 4 due to the action of the reflected potential 17 applied to the inner cylindrical electrode 1 and the outer cylindrical electrode 2. After passing through five energy analysis stages B1 to B5, the light exits from the exit hole 7 and is detected by the ion detector 11.

Of the ions that entered the ion acceleration stage A from the ion source 9, the entrance hole 6 receives the acceleration potential 19 applied to the inner cylindrical electrode 1 and the reflected potential 17 applied to the inner cylindrical electrode 1 and the outer cylindrical electrode 2. As a result of this action, only ions with uniform initial energies that define a secondary focused ion trajectory 18 passing through the circular entrance slit 3 and the circular exit slit 4 arrive.

The ion detection signal 2o detected by the ion detector 11 and amplified by the amplifier 14 is sent to the oscilloscope 1 at the same time as the timing pulse signal 21 from the timing pulse generator 16.
5 will be displayed on the screen. In this way, the flight time of ions from the entrance hole 6 to the ion detector 11 is observed as the time delay t of the timing pulse signal 21 of the ion detection signal 20.

FIG. 2 explains the detailed structure of the timing electrode 5 and its driving circuit.

In Fig. 2, numerals 51, 52, 53, and 54 are alumina ceramic plates, and metallizing ink is applied to the surfaces of the raw materials 52, 53, and 54, respectively, in a kneaded and dry state before firing, and the same is kneaded. When the raw material of the semi-dried alumina ceramic plate 51 is fired, the metallized ink becomes conductive and becomes a parallel plate electrode with the symbol S5, 56.57, and the whole is integrated to form the timing electrode plate 5.

The small circular hole 6 is an ion entrance hole opened in the center of the timing electrode plate 5, and when the parallel plate electrodes 55 and 57 are set at the same potential as the internal cylindrical electrode 1 and a voltage is applied to the parallel plate electrode 56, the small circular hole is opened. 6, an unequal electric field is generated, and the ions passing through it are deflected and deviate from the focused trajectory, and are unable to pass through the next energy analysis stages B1 to B5 (1° NPN in Fig. 2). The circuit including 161 is part of the output stage of timing pulse generator 16, and when no voltage is applied to terminal 162, transistor 16
1 is deeply biased and the parallel plate electrode 56 has +2
0V is applied. When a positive voltage is applied to the terminal 162, a saturation current flows through the transistor 161, the parallel plate electrode 56 becomes the same potential as the inner cylindrical electrode 1, and the small circular hole 6
The ions passing through can pass through the next energy analysis stages 81 to B5.

By the way, FIGS. 3 to 6 show experimental examples of the apparatus of the present invention, in which a potential ■l is applied to the internal cylindrical electrode 1, a potential v2 is applied to the external cylindrical electrode 2, and a potential ■l is applied to the accelerating electrode A1. . is applied.

The ion incidence angle α is 42.3± including the deviation Δα of the incidence angle.
Since it is set to 2.5 (deg), the length Z to the focal point is as shown in FIG. The change in is small, and the flight time 8th T is also small. (See Figure 5) The maximum diameter rm from the axis of the ion orbit is r when a = 42.3 (deg).
m = 1, 8 r, howling. Here, the symbol r1 is the inner diameter of the inner cylindrical electrode 1, which is 10 (mm
). ,.

Furthermore, the inner diameter r2 of the external cylindrical electrode 2 is 20 (ma+), and the length Z per step. is Zo=6. Ir, I'm yelling.

Potential V of accelerating electrode A1. and inner and outer cylindrical electrodes 1
．． The potentials V, , V2 of 2 have the following relationship.

Vo = 1.88 (V, -V2) Here, by reducing the change in deceleration voltage △V, (%), the length to the focal point Zo can be reduced as shown in Figure 6.
The change in (mn+) can be made small.

In this experimental example, in order to focus the ions, the initial energy difference must be less than 103, and the incident angle α
By narrowing the width of
It is possible to do more than that.

In the experimental example shown in Figure 3, a needle-shaped electrode is used as the timing electrode, but with this shape, the size of the disturbance electric field is
It was not possible to make it less than mm. By using parallel plate electrodes like the timing electrodes in the example in FIG. 2 and setting the electrode spacing and the size of the small hole 6 to 0.5 ωm, the size of the disturbance electric field becomes 0.5+oa+, and the analyzer can be miniaturized. . 1 In addition, the ions are not limited to cations, but anions may also be used. In this case, each power source 17.19 and the electrode 5
The voltage may be set appropriately.

As detailed above, according to the time-of-flight ion mass spectrometer of the present invention, only ions with uniform initial energy that satisfy the ion secondary focusing conditions can be detected by the ion detector without damaging the solid angle at the time of incidence. This has the effect of increasing sensitivity and resolution.

[Brief explanation of the drawing]

The figures show a time-of-flight ion mass spectrometer as an embodiment of the present invention; FIG. 1 is a schematic diagram thereof, and FIG. 2 is an explanatory diagram showing the detailed structure of its timing electrode and drive circuit; FIG. 3 is a schematic diagram showing the main part thereof, and FIGS. 4 to 6 are graphs for explaining its operation. 1. Internal cylindrical electrode, 2. External cylindrical electrode, 3. Circular entrance slit, 4. Circular exit slit, 5. Timing electrode, 6. Inlet hole, 7. Output hole, 8. Exhaust. System, 9...Ion source, 10...Ion intake hole, 1
1. An ion detector constituting an ion detection means, 12.
・Exhaust system, 13・・Ion detector mortar jJD power supply, 14・
- Amplifier constituting the ion detection means, 15... Oscillograph, 16... Timing pulse generator, 17... Reflection potential, 18... Ion trajectory, 19... Calo speed potential, 2
0...Ion detection signal 1.21...Timing pulse signal, 51.52.53.54-Alumina ceramic plate,
55, 56.57...Parallel plate electrode, 161...NPN
) transistor, 162... terminal, A... ion acceleration stage,
A1...acceleration electrode, 81-B5...energy analysis stage. Agent Patent Attorney Yoshihiko Iinuma

Claims (4)

[Claims] (1) An ion acceleration means, an entrance hole through which the ions accelerated by the acceleration means pass, and a plurality of energies for performing energy analysis by emitting and focusing the ions accelerated by the acceleration means at a required angle. an analysis stage; an exit hole disposed at the final stage of the energy analysis stage;
ion detection means for detecting ions passing through the emission hole, the energy analysis stage comprising: an external cylindrical electrode acting as an outer pole of the energy analysis stage; an inner cylindrical electrode that acts as an inner pole of the energy analysis stage, and the inner cylindrical electrode causes the fine soil to absorb the energy by a reflected potential applied to the inner cylindrical electrode and the outer cylindrical electrode. an entrance slit that allows ions passing through the entrance end of the analysis stage to pass toward the external cylindrical electrode; and a trajectory that reflects the incident ions by the external cylindrical electrode and focuses the ions at the exit end of the energy analysis stage. What is claimed is: 1. A time-of-flight ion mass spectrometer, comprising: an exit slit; and a timing electrode that allows ions to pass through the entrance hole for a predetermined time period. (2) Claims characterized in that the ion accelerating means is an additional energy analysis stage having the same structure as the plurality of energy analysis stages and disposed coaxially with the energy analysis stages. The time-of-flight ion mass spectrometer according to item 1. (3) In the energy analysis stage, ions passing through the axis at the entrance end of the energy analysis stage at a conical solid angle having the apex angle at the angle are focused at the exit end of the energy analysis stage. 3. A time-of-flight ion mass spectrometer according to claim 1 or 2, characterized in that the energy analysis stage is arranged in a secondary focusing arrangement. (4) The timing electrode is composed of a ceramic disk having a hole in the center and a plurality of metalized parallel plate electrodes, and the timing electrode is composed of a ceramic disk having a hole in the center and a plurality of metalized parallel plate electrodes, and the interference electric field created in the hole of the parallel plate electrode , the time-of-flight ion mass spectrometer described in II@Claims 1 to 3 of Patent No. 84, characterized in that ions are prevented from passing through the hole.