JPS5953501B2 - mass spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mass spectrometer equipped with a detector into which ions separated by a magnetic field are incident, and is particularly suitable for obtaining several types of spectra with different resolutions only by electrical operation. related to a mass spectrometer.

FIG. 1 shows a schematic diagram of the detector portion of a conventional mass spectrometer.

In the figure, 10 is an ion beam separated by a magnetic field, and 12 is a single slit formed on the converging surface of the ion beam 10 to separate the ion beams 10 passing through different trajectories. collector slit, 14,
15 is a deflection electrode for deflecting ions that have passed through the collector slit 12; 16 is an ion regulation slit formed with a single slit that allows only ions deflected by the deflection electrodes 14 and 15 to pass; 18 is an ion regulation slit; A secondary electron multiplier tube 20 is used to amplify the ions that have passed through the regulation slit 16, and 20 is a collector that detects the signal amplified by the secondary electron multiplier tube 20. In such a conventional mass spectrometer, ions separated by a magnetic field cross the collector slit 12 by changing the magnetic field, and the ions incident on the collector slit 12 are deflected by the deflection electrodes 14 and 15, and the ions are The electrons pass through the regulation slit 16, are amplified by the secondary electron multiplier 18, and are detected by the collector 20.
In this case, since the ion beam is deflected by the deflection electrodes 14 and 15, neutral particles and scattered ions contained in the ion beam are removed. In such a conventional mass spectrometer, in order to change the spectral resolution, the width of the collector slit can be changed outside the vacuum by making the collector slit 12 a variable slit, or by making the fixed slit movable in parallel. , it was necessary to change it mechanically. Therefore, not only is the apparatus complicated, but it is also difficult to quickly switch between two spectra, one with low ion current but high resolution, and the other with high ion current but low resolution. . On the other hand, in order to eliminate such drawbacks, a mass spectrometer has been proposed in which a plurality of slits with different slit widths are formed in the collector slit and a different detector is installed in each slit.
Since it is necessary to provide a detector for each slit, there is a problem in that the device becomes extremely expensive. The present invention was made to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a mass spectrometer that can obtain several types of vectors with different resolutions by electrical operation.

The present invention provides a mass spectrometer equipped with a detector into which ions separated by a magnetic field are incident. , an electric deflection device capable of guiding only ions passing through a single slit to a detector by switching a deflection voltage;
The above objective has been achieved by providing the following.

Additionally, there is an electric field device for deflecting ions, a lens field device for converging ions that have passed through the electric field device, a magnetic field device for deflecting ions again that have passed through the lens field device, and a lens field device for converging ions that have passed through the lens field device. a detector into which ions are incident;
In a double focusing mass spectrometer equipped with a collector slit in which a plurality of slits with different slit widths are formed, and of the ions that have passed through the collector slit, only the ions that have passed through a single slit are By providing an electrical deflection device that can guide the ions to the detector by switching the deflection voltage, and by linking the deflection voltage of the electrical deflection device and the lens voltage of the lens field device, the focused state of the ions can be controlled. The slit can be switched without deterioration. Embodiments of the present invention will be described in detail below with reference to the drawings.

In the first embodiment of the present invention, the present invention is applied to a mass spectrometer equipped with a detector into which ions separated by a magnetic field are incident.As shown in FIG.
Two slits 24 and 26 with different slit widths are formed in the deflection electrodes 14 and 15.
, 26, a deflection voltage is applied that can guide only the ions that have passed through one of the slits to the detector. The collector slit 22 has a width of 50 μm for the slit 24 and a width of 500 μm for the slit 26, for example.
The distance between the two can be set to 10 mm.

Further, the ion regulating slit 16 may have a slit with a width of 5 mm located midway between the slits 24 and 26, that is, at a position 5 mm apart.

Also, the length of the deflection electrode 14 is 30 mm, and the interval is 20 mm.
It can be done.

In the above case, when positive ions accelerated at 2 kV are incident on the slit 24, the deflection electrode 14 receives +
If -440V is applied to 440V, 15, ions can pass through the ion restriction slit 16.

On the other hand, at this time, since the ions incident through the slit 26 are deflected by 11 mm or more from the center of the ion regulating slit 16, the unnecessary ions will not be incident on the secondary electron multiplier 18. In addition, when detecting only positive ions incident on the slit 26, the deflection electrode 14 is supplied with -550V and 15V.
When +550V is applied to the slit 26, only the ions entering from the slit 26 enter the center of the ion regulating slit 16 and are detected by the secondary electron multiplier 18. In this case, the ions incident on the slit 24 pass through the ion regulating slit 1.
Since the electron beam is deflected by 11 mm or more from the center of the electron beam 6, it does not enter the secondary electron multiplier tube 18. By switching the deflection voltage as described above, when the slit 24 is used, a mass spectrometer with a dispersion coefficient of 10c[n has a resolution of 1000
, when using slit 26, the resolution is also 100
Spectra are obtained alternately.

In the above case, as in the conventional example shown in FIG. 1, neutral particles, scattered ions, etc. are also removed at the same time, so that a clean spectrum can be obtained.

However, in the fan-shaped magnetic field type mass spectrometer, the image is formed at only one point, and if the slits are installed at different locations as shown in FIG. 2, the image will be formed only at one of them. Therefore, in order to obtain a low-resolution spectrum, the slit may be placed at a position away from the convergence point, but in this case, some loss of ions due to blurring of the image cannot be avoided. Such problems can be eliminated in the second embodiment, which is applied to a double convergence type mass spectrometer as shown in FIG. In the figure, 30 is an ion source, 31 is an object point slit, 32 is an electric field device for deflecting ions, and 34 is a quadrupole lens, which is a lens field device for converging the ions that have passed through the electric field device 32. 36 is a parallelogram magnetic field device for deflecting the ions that have passed through the quadrupole lens 34 again; 38 is a deflection electrode power supply that applies a deflection voltage to the deflection electrodes 14 and 15; 40 is a quadrupole lens This is a lens power source that provides a lens voltage to be applied to 34. The other points are the same as those of the first embodiment, so the explanation will be omitted. In such a double convergence type mass spectrometer, since a parallelogram-shaped magnetic field is used, the magnetic field has no convergence effect, and ions are converged by the quadrupole lens 34.

Therefore, the imaging point of the ion beam is not fixed geometrically, but can be imaged at any position by changing the ins voltage. Therefore, by interlocking the deflection electrode power supply 38 and the lens power supply 40, it becomes possible to switch the collector slit without deteriorating the beam convergence state. The lens voltage to obtain the best convergence conditions can be set in advance. In addition, in each of the above embodiments, the number of slits provided on the colletata slit was two;
In principle, it is possible to install even more slits.

Further, some of the plurality of slits may be mechanically adjustable variable slits. As explained above, the present invention provides a mass spectrometer equipped with a detector into which ions separated by a magnetic field are incident, including a collector slit in which a plurality of slits with different slit widths are formed;
Of the ions that have passed through the collector slit, an electrical deflection device that can guide only the ions that have passed through a single slit to the detector by switching the deflection voltage is installed, so that the resolution can be improved. Several different types of spectra can be obtained by switching rapidly by electrical operation.

Furthermore, since there is no need to use mechanically variable slits, there is an excellent effect in that the cost can be reduced. Additionally, there is an electric field device for deflecting ions, a lens field device for converging ions that have passed through the electric field device, a magnetic field device for deflecting ions again that have passed through the lens field device, and a lens field device for converging ions that have passed through the lens field device. A collector slit in which a plurality of slits having different slit widths are formed in a double focusing mass spectrometer equipped with a detector into which ions are incident;
An electrical deflection device is provided that can guide only the ions that have passed through a single slit out of the ions that have passed through the collector slit to the detector by switching the deflection voltage. Since the deflection voltage of the ion beam is linked with the lens voltage of the lens field device, an excellent effect is obtained in that the slit can be switched without deteriorating the ion convergence state.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a detector portion of a conventional mass spectrometer, FIG. 2 is a schematic configuration diagram showing a detector portion of a first embodiment of a mass spectrometer according to the present invention, and FIG. 1 is a schematic configuration diagram showing the configuration of a double convergence type mass spectrometer to which a second embodiment of the mass spectrometer according to the present invention is applied. 10...Ion beam, 16... ...Ion regulation sukawanote, 14,15...Deflection electrode, ]8...Secondary electron multiplier, 20...
Collector, 22... Collector slit, 24,
26... Slit, 30... Ion source, 32... Electric field device, 34... Quadrupole lens, 36... Magnetic field device , 38...
Deflection electrode power supply, 40... Lens power supply.

Claims (1)

[Claims] 1. A mass spectrometer equipped with a detector into which ions separated by a magnetic field are incident, including a collector slit in which a plurality of slits with different slit widths are formed, and ions passing through the collector slit. A mass spectrometer comprising: an electrical deflection device capable of guiding only ions that have passed through a single slit to a detector by switching a deflection voltage. 2. An electric field device for deflecting ions, a lens field device for converging ions that have passed through the electric field device, a magnetic field device for re-deflecting ions that have passed through the lens field device, and an ion that has passed through the magnetic field device. a detector on which is incident;
In a double focusing mass spectrometer equipped with a collector slit, in which multiple slits with different slit widths are formed, only the ions that have passed through a single slit out of the ions that have passed through the collector slit are By switching the ions, an electric deflection device that can guide the ions to the detector is provided, and by linking the deflection voltage of the electric deflection device and the lens voltage of the lens field device, the convergence state of the ions is deteriorated. A mass spectrometer characterized in that the slit can be switched without any trouble.