JP3761752B2 - Time-of-flight mass spectrometer with orbit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a time-of-flight mass spectrometer (TOFMS), and more particularly to a time-of-flight mass spectrometer having a closed trajectory in which ions can circulate.
[0002]
[Prior art]
In a time-of-flight mass spectrometer, based on the fact that sample ions accelerated with a constant acceleration energy have a flight speed corresponding to the mass, the time of flight required to fly a certain distance is measured to determine the mass.
[0003]
The resolution of this time-of-flight mass spectrometer is proportional to the flight distance of ions when the ion source conditions are the same. Therefore, in order to achieve high resolution, the flight distance may be increased, but this usually leads to an increase in the size of the apparatus.
[0004]
Therefore, in order to make the flight distance longer and to reduce the size of the apparatus, for example, a U-turn is performed by changing the flight direction of ions using an electric field called a reflectron. Furthermore, there is an attempt to realize a long flight distance by forming a closed trajectory using a plurality of electric fields and circulating ions on the trajectory.
[0005]
[Problems to be Solved by the Invention]
Even if the flight direction is made a U-turn using the reflectron, it is inevitable to increase the size of the device in order to increase the flight distance. In the case of having an orbit, it is possible to increase the flight distance in a limited space by making multiple orbits, but it is necessary to devise ion beam entrance and exit.
[0006]
An object of the present invention is to provide a time-of-flight mass spectrometer capable of easily entering and exiting ions by combining a reflectron with a time-of-flight mass spectrometer having a circular orbit.
[0007]
[Means for solving the problems]
In order to achieve this object, the present invention is a time-of-flight mass spectrometer having an orbit, comprising an ion generator and an ion reservoir for containing the generated ions on the orbit , from the ion reservoir. An ion source for extracting ions in one direction in a pulsed manner is arranged, and the ion source is arranged so as to send out ions on the orbit, and when the ion source is not operated , ions traveling on the orbit It is configured to pass through the ion reservoir .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an ion optical diagram showing an example of a time-of-flight mass spectrometer embodying the present invention. In FIG. 1, four fan-shaped electric fields E1, E2, E3, and E4 whose turning angles are smaller than 180 ° are arranged in a curved portion of the figure 8, thereby forming a closed ion trajectory A having a figure eight shape. . This orbit A is composed of circular orbits A1 to A4 in the four sector electric fields E1 to E4 and four rectilinear orbits A12, A23, A34 and A41 connecting the sector electric fields.
[0009]
An orthogonal (orthogonal) ion source 1 is arranged on the straight trajectory A12 between the sector electric fields E1 and E2 so that ions can be emitted toward the sector electric field E2 on the straight trajectory A12. The ion source 1 includes an ionization unit 2 and an ion reservoir 3 into which ions generated on the linearization trajectory are introduced at a low speed. An extraction electrode 4 and an extrusion electrode 5 are provided in the ion reservoir 2, and by applying a voltage between the two electrodes, an electric field for giving acceleration energy to the ions and extracting them to the outside is generated. . The ion reservoir 3 is provided with a passage port so that ions traveling along the straight traveling path A12 can pass through without being affected when the ion source is not operated.
[0010]
A reflectron 6 is arranged on a straight path A12 between the ion source 1 and the sector electric field E2. The reflectron 6 generates an electric field for decelerating ions by at least two electrodes arranged at intervals, and makes the U-turn by making the ions incident obliquely on the electric field. An ion detector 7 is provided to detect ions whose traveling direction has been changed by the reflectron 6 and deviated from the straight trajectory A12. In addition, the reflectron 6 is provided with a passage opening and all the electrodes are set to the ground potential so that ions traveling along the straight track A12 can pass through without being influenced when the reflectron 6 is not operated.
[0011]
In such a configuration, the sample ions generated by the ionization unit 2 are taken out from the ionization unit at a low speed, and are guided in the direction of the arrows into the ion reservoir 3. When an appropriate amount of ions is accumulated, by supplying a voltage to the extraction electrode and the extrusion electrode in a pulsed manner, the ions in the ion reservoir are extracted out in a pulsed manner and start to travel along the straight trajectory A12.
[0012]
In the ion reservoir, the ions are traveling at the velocity V0 imparted by the ionization section, so even if an electric field for extraction is applied in a direction orthogonal to the traveling direction, the ions are not extracted in the direction of the electric field. However, it is emitted obliquely with respect to the direction of the electric field due to the influence of the velocity V0. Needless to say, the ion source 1 is arranged so that the emission direction thereof coincides with the straight traveling path A12.
[0013]
In this way, the pulsed group of ions launched from the ion source 1 and started to fly along the straight traveling trajectory A12 are developed according to the mass with the passage of time. In the low resolution mode where the resolution required for the mass spectrometer is the lowest, the reflectron 6 is always activated. Accordingly, the ions emitted from the ion source 1 are taken out of the rectilinear trajectory A12 as soon as they arrive at the reflectron 6 and enter the detector 7 to be detected.
[0014]
On the other hand, in the high resolution mode where higher resolution is required, the reflectron 6 is initially inactivated. Therefore, the ions emitted from the ion source 1 pass through the reflectron 6 and fly along the following circular orbits A2, A23, A3, A34, A4, A41, A1, and make one round to make the ion source 1 Come back to. Since the ion source 1 is in a non-operating state until the ion returns after one round after launching, the ion passes through the ion source 1 as it is and reaches the reflectron 6. Since the reflectron 6 is in an activated state between the passage of ions and approaching again, the ions that have reached the reflectron 6 are taken out of the rectilinear trajectory A12 as they arrive and are detected by the detector 7. And is detected. Since the flight distance of ions at this time is longer than that in the low resolution mode by one orbit of the orbit, it is possible to measure with higher resolution than in the low resolution mode.
[0015]
By further increasing the number of ion turns, it is possible to cope with a case where higher resolution is required. That is, if the timing at which the reflectron 6 is activated is further delayed, the ions are further circulated. Therefore, when the desired number of laps is accumulated, the reflectron is activated and the ions are detected. . However, since analysis becomes difficult if the first ion overtakes the last ion, the reflectron is activated before the overtaking occurs, and the last ion passes through the reflectron. Needless to say, this is the timing before the leading ion reaches the reflectron 6.
[0016]
The present invention can be modified without being limited to the above-described embodiments. For example, as shown in FIG. 2, the ion source 11 may be provided on an extension line of a straight trajectory, and ions may be driven into the circular trajectory through a hole formed in an electrode forming a sector electric field.
[0017]
【The invention's effect】
As described in detail above, in the present invention, an ion source composed of an ion generation unit and an ion reservoir that stores generated ions is arranged on a circular orbit, and the orbit from the outside of the orbit using this ion source. It is configured so that ions can be sent out and allowed to fly , and ions that travel around the orbit when the ion source is not operated can pass through the ion reservoir , so that the time-of-flight type that can easily enter and exit ions A mass spectrometer is realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of an embodiment of the present invention.
FIG. 2 is a diagram showing a modification of the present invention.
[Explanation of symbols]
E1, E2, E3, E4 ... Fan electric field, 1 ... Orthogonal ion source, 6 ... Reflectron, 7 ... Ion detector

Claims (2)

A time-of-flight mass spectrometer having an orbit, comprising an ion generator and an ion reservoir for storing the generated ions on the orbit , and extracting ions from the ion reservoir in one direction in a pulsed manner. A source is arranged, and the ion source is arranged so as to send out ions on the orbit, and when the ion source is not operated, the ions traveling on the orbit can pass through the ion reservoir. A time-of-flight mass spectrometer having a circular orbit characterized by: It is configured so that ions traveling in the orbit using a reflectron can be extracted and detected outside the orbit, and the ion traveling in the orbit can pass through the reflectron when the reflectron is not operated. The time-of-flight mass spectrometer having a circular orbit according to claim 1.

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