Time-of-flight mass spectrometer

Abstract

The present invention relates to a time-of-flight mass spectrometer, comprising: a main electrode (21), comprising an outer electrode (211) arranged on the outer side of an orbit and an inner electrode (212) arranged on the inner side; an ion introduction port (22); an ion discharge port (23), arranged on either side of the outer electrode or the inner electrode; a surrounding voltage application unit (28), applying a surrounding voltage to the outer electrode and the inner electrode; a group of deflection electrodes (24), arranged opposite to each other with a predetermined orbit in between, comprising a first partial electrode (241) facing the predetermined orbit and a second partial electrode (242) constituting a portion other than the first partial electrode; and a voltage application unit (29), applying a deflection voltage to the first partial electrode for reversing the drift direction of ions flying on the predetermined orbit, and applying a voltage to the second partial electrode for forming a surrounding electric field.

Description

Technical Field

[0001] The present invention relates to a time-of-flight mass spectrometer. Background Art

[0002] One type of mass spectrometer is a time-of-flight mass spectrometer (TOF-MS). In TOF-MS, a predetermined acceleration energy is given to the ion group generated from the sample and introduced into the flight space, so that the ions that fly a predetermined length of track in the flight space are detected by the ion detector in sequence, and the intensity at each time point is recorded. The time (flight time) required for ions given the same energy to fly a predetermined length of track varies according to the mass-to-charge ratio of the ions. In TOF-MS, the relationship between the mass-to-charge ratio and the flight time of the ions is calculated in advance, and based on this relationship, the flight time of each ion is converted into a mass-to-charge ratio to obtain a mass spectrum.

[0003] In TOF-MS, the longer the trajectory of the ions, the more the ions can be separated according to different mass-to-charge ratios, and the higher the mass resolution. However, if the trajectory is lengthened by simply making the ions fly in a straight line, the mass analyzer will become larger. In order to lengthen the trajectory of the ions without making the mass analyzer larger, a reflection-type mass analyzer and a closed-orbit multi-circle mass analyzer have been proposed. In a reflection-type mass analyzer, the flight direction of the ions is reversed by using a reflection electrode, so that the ions travel back and forth in the flight space to lengthen the distance they fly. In addition, in a closed-orbit circling mass analyzer, the distance they fly is lengthened by making the ions fly repeatedly in a single circling orbit (closed orbit).

[0004] In a reflectron mass spectrometer, although it is possible to obtain a flight distance that is about twice the distance of the ions flying in a straight line, the flight distance cannot be extended further. In addition, in an orbital mass spectrometer, due to repeated flight in a closed orbit, ions with a smaller mass-to-charge ratio and a faster flight speed will overtake ions with a larger mass-to-charge ratio and a slower flight speed, making it impossible to distinguish ions with different flight distances, resulting in the so-called overtaking problem.

[0005] Therefore, open-orbit (quasi-closed-orbit) multi-turn time-of-flight mass spectrometers (MT-TOF-MS: Multi Turn TOF-MS) and multi-reflection time-of-flight mass spectrometers (MR-TOF-MS: MultiReflection TOF-MS) have been proposed recently (eg, Patent Documents 1-3).

[0006] In MT-TOF-MS, circular, elliptical, 8-shaped and other orbits are defined in the flight space, so that the ions move (drift) little by little in the specified direction each time they circle, and the ions circle repeatedly. In addition, in MR-TOF-MS, two reflective electrodes are arranged opposite to each other with the flight space sandwiched between them, so that the ions move (drift) little by little in the specified direction each time they go back and forth between these reflective electrodes, and the ions repeatedly go back and forth. By adopting these structures, the mass resolution can be improved by lengthening the flight distance of the ions without enlarging the mass analyzer.

[0007] For example, the MT-TOF-MS described in Patent Document 1 is provided with an outer electrode of a roughly spheroidal shape and an inner electrode of a roughly spheroidal shape, and an orbit-regulating electrode for regulating the orbit of ions between these outer electrodes and the inner electrode, the outer electrode being composed of a plurality of segment electrodes, and the inner electrode being arranged on the inner side of the outer electrode and being composed of a plurality of segment electrodes arranged opposite to each segment electrode constituting the outer electrode. In this MT-TOF-MS, a predetermined voltage is applied to the plurality of segment electrodes constituting the outer electrode and the plurality of segment electrodes constituting the inner electrode, respectively, to form an electrostatic field (orbital electric field) that causes ions to repeatedly orbit in the spheroidal space (flight space) between the outer electrode and the inner electrode. An ion introduction port for introducing ions into the orbit of ions and an ion discharge port for discharging ions from the orbit of ions are provided on the outer electrode. The ions introduced into the flight space from the ion introduction port fly in an orbit that rotates successively at a predetermined angle (drift angle) around the axis of the roughly spheroidal shape each time they orbit. The ions that have circled a predetermined number of times (for example, 20 to 30 times) are ejected from the ion ejection port to the outside of the flight space and detected by the ion detector.

[0008] Patent document 1 also proposes to configure a set of deflection electrodes sandwiching the first orbit of the orbit of the ion, and to apply a predetermined voltage (deflection voltage) to the electrodes to form a deflection electric field. In this MT-TOF-MS, after the ions are orbited for a predetermined number of times, the drift direction is reversed by the deflection electric field, and after the ions are orbited for a predetermined number of times again, the ions are discharged out of the flight space. If such a configuration is adopted, the number of ion orbits and the flight distance can be increased compared to the case where the deflection electric field is not used to further improve the mass resolution.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application No. 2014-531119

[0012] Patent Document 2: Japanese Patent Application No. 2013-517595

[0013] Patent Document 3: Japanese Patent Application No. 2018-517244 Summary of the invention

[0014] Technical problem to be solved by the invention

[0015] However, it is known that in practice, if the deflection electrodes as above are configured in MR-TOF-MS to apply a deflection voltage, the deflection electric field thus formed will not only deflect the ions flying in the prescribed orbit, but will also deflect the ions flying in the adjacent orbit, making it impossible for the ions to fly in the prescribed orbit.

[0016] Here, an MT-TOF-MS is described in which the flight trajectory of ions is rotated successively by a specified angle during each orbit. However, the same problem mentioned above may also occur in an MT-TOF-MS (for example, Patent Document 1) or MR-TOF-MS in which the flight trajectory of ions is displaced successively by a certain amount in a specified direction during each orbit.

[0017] The technical problem to be solved by the present invention is to provide a technology that, in a multi-circling or multi-reflection time-of-flight mass spectrometer, when ions flying in a predetermined circle of orbital orbit or a predetermined round-trip orbit are deflected to reverse the drift direction, suppresses the unwanted deflection of ions flying in orbits other than the predetermined circle of orbital orbit or the predetermined round-trip orbit.

[0018] Solutions for solving the above technical problems

[0019] A first aspect of the time-of-flight mass spectrometer of the present invention, which has been accomplished to solve the above-mentioned technical problems, comprises:

[0020] The orbit defining electrode is an electrode for forming an orbiting electric field for defining an orbit in which the ions repeatedly orbit while drifting in a predetermined direction each time, and includes an outer electrode arranged outside the orbit and an inner electrode arranged inside the orbit;

[0021] An ion introduction port for introducing ions into the orbit;

[0022] an ion ejection port for ejecting ions from the orbit;

[0023] A surrounding voltage applying unit applies surrounding voltages to the outer electrode and the inner electrode respectively to form the surrounding electric field;

[0024] a set of deflection electrodes disposed opposite to each other with the first predetermined orbit of the orbit sandwiched therebetween, and comprising a first partial electrode facing the first predetermined orbit and a second partial electrode constituting a portion other than the first partial electrode;

[0025] The voltage applying unit applies a deflection voltage for reversing the drift direction of ions flying in the predetermined orbit to the first partial electrode, and applies a voltage for forming the orbiting electric field to the second partial electrode.

[0026] Furthermore, a second aspect of the time-of-flight mass spectrometer of the present invention, which has been accomplished to solve the above-mentioned technical problems, comprises:

[0027] The reciprocating trajectory defining electrode is an electrode defining a reciprocating electric field for defining a reciprocating trajectory for causing the ions to drift in a predetermined direction each time they reciprocate, and includes a set of reflection electrodes disposed on both sides of the flight space of the ions;

[0028] An ion introduction port for introducing ions into the reciprocating track;

[0029] An ion discharge port for discharging ions from the round-trip track;

[0030] A reciprocating voltage applying unit, applying a reciprocating voltage to each of the group of reflective electrodes to form the reciprocating electric field;

[0031] a set of deflection electrodes disposed opposite to each other with a predetermined first reciprocating track sandwiched therebetween, and comprising a first partial electrode facing the predetermined first reciprocating track and a second partial electrode constituting a portion other than the first partial electrode;

[0032] The voltage applying unit applies a deflection voltage for reversing the drift direction of ions flying in the predetermined round-trip orbit to the first partial electrode, and applies a voltage for forming the round-trip electric field to the second partial electrode.

[0033] Effects of the Invention

[0034] The first scheme of the present invention is a multi-circling time-of-flight mass spectrometer (MT-TOF-MS) with an open orbit (quasi-closed orbit). In this mass spectrometer, a predetermined orbital voltage is applied to the outer electrode and the inner electrode constituting the orbital defining electrode to form an orbital electric field for defining the orbital orbit in which ions fly. Ions are introduced into the orbital orbit from the ion introduction port, and fly in the orbital orbit while drifting in a predetermined direction during each orbit. In the orbital orbit of the first predetermined circle in the orbital orbit, a group of deflection electrodes is arranged to sandwich the orbital orbit. The deflection electrode has a first partial electrode facing the orbital orbit of the first predetermined circle and a second partial electrode constituting a portion other than the first partial electrode. By applying a deflection voltage to the first partial electrode, the drift direction of the ions flying in the orbit is reversed. At this time, the deflection voltage is applied only to the first partial electrode facing the orbital orbit of the first predetermined circle in the deflection electrode, and a voltage for forming an orbital electric field is applied to the second partial electrode constituting the portion other than the first partial electrode. Since a deflection voltage is applied to the entire deflection electrode in the previous MT-TOF-MS, a deflection electric field is formed in a larger range around the deflection electrode, so that ions flying in the orbit adjacent to the orbit of the first specified circle are also deflected. In the first scheme of the present invention, since a voltage for forming a surrounding electric field is applied to the second partial electrode outside the part facing the orbit of the first specified circle, it is possible to suppress the unexpected deflection of ions caused by the disorder of the surrounding electric field of the orbit adjacent to the orbit of the first specified circle.

[0035] In addition, the second scheme of the present invention is a multiple reflection time-of-flight mass spectrometer (MR-TOF-MS). In this mass spectrometer, a predetermined reciprocating voltage is applied to a group of reflection electrodes arranged on both sides of the flight space of the ions, so as to form a reciprocating electric field for defining the reciprocating orbit in which the ions fly. The ions are introduced into the reciprocating orbit from the ion introduction port, and fly in the reciprocating orbit while drifting in a predetermined direction each time they go back and forth. In the predetermined reciprocating orbit in the reciprocating orbit, a group of deflection electrodes is arranged to sandwich the reciprocating orbit. The deflection electrode has a first partial electrode facing the predetermined reciprocating orbit and a second partial electrode constituting a portion other than the first partial electrode. By applying a deflection voltage to the first partial electrode, the drift direction of the ions flying in the orbit is reversed. At this time, the deflection voltage is applied only to the first partial electrode facing the predetermined reciprocating orbit in the deflection electrode, and a voltage for forming a reciprocating electric field is applied to the second partial electrode constituting the portion other than the first partial electrode. Similarly, in the mass spectrometer of the second scheme, since a reciprocating electric field is formed on the second partial electrode other than the portion facing the specified reciprocating orbit, it is possible to suppress the unwanted deflection of ions caused by the disorder of the deflection electric field of the reciprocating orbit adjacent to the specified reciprocating orbit. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a diagram showing the main structure of a multi-surrounding time-of-flight mass spectrometer (MT-TOF-MS) which is one embodiment of the time-of-flight mass spectrometer of the present invention.

[0037] Figure 2 It is a top view of the MT-TOF-MS according to this embodiment.

[0038] Figure 3 This is a diagram for explaining orbits in the MT-TOF-MS according to the present embodiment.

[0039] Figure 4 This is a diagram for explaining the arrangement of deflection electrodes in the MT-TOF-MS according to the present embodiment.

[0040] Figure 5 This is a diagram for explaining a portion where a deflection voltage is applied to a deflection electrode and a portion where a surround voltage is applied in the MT-TOF-MS of the present embodiment.

[0041] Figure 6 This is a diagram for explaining the deflection electric field in conventional MT-TOF-MS.

[0042] Figure 7 This is a diagram for explaining the deflection electric field in the MT-TOF-MS according to the present embodiment.

[0043] Figure 8 This is a diagram for explaining the arrangement of deflection electrodes in a MT-TOF-MS according to a modified example.

[0044] Fig. 9 This is a diagram for explaining a portion where a deflection voltage is applied to a deflection electrode and a portion where a surround voltage is applied in an MT-TOF-MS according to a modified example.

[0045] Fig.10 This is a diagram for explaining the configuration of another modified example of MT-TOF-MS.

[0046] Fig.11 It is a diagram showing the main structure of a multi-reflection time-of-flight mass spectrometer (MR-TOF-MS) which is one embodiment of the time-of-flight mass spectrometer of the present invention.

[0047] Fig.12 This is a diagram for explaining a portion where a deflection voltage is applied to a deflection electrode and a portion where a reciprocating voltage is applied in the MR-TOF-MS of the present embodiment.

[0048] Fig.13 This is a diagram for explaining the arrangement of deflection electrodes in an MR-TOF-MS according to a modified example.

[0049] Fig.14 This is a diagram for explaining a portion where a deflection voltage is applied to a deflection electrode and a portion where a reciprocating voltage is applied in an MR-TOF-MS according to a modified example.

[0050] Fig.15 This is an example of a deflection electrode that can be used in the time-of-flight mass spectrometer of the present invention.

[0051] Fig.16 This is another example of a deflection electrode that can be used in the time-of-flight mass spectrometer of the present invention.

[0052] Fig.17 This is another example of a deflection electrode that can be used in the time-of-flight mass spectrometer of the present invention. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the time-of-flight mass spectrometer of the present invention, namely, an open-orbit (quasi-closed-orbit) multiple-circuit time-of-flight mass spectrometer (MT-TOF-MS) and a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS), will be described with reference to the accompanying drawings.

[0054] (1) One embodiment of MT-TOF-MS

[0055] The main components of the MT-TOF-MS1 of this embodiment are as follows: Figure 1 to Figure 4 The MT-TOF-MS 1 of this embodiment includes an ion source 11 , an ion flight unit 20 , and an ion detector 12 .

[0056] The ion source 11 includes, for example, an ionization unit for ionizing a sample and an ion trap for temporarily retaining ions. Ions with various mass-to-charge ratios generated from the sample in the ionization unit are temporarily captured by the ion trap, cooled by a cooling gas, and then given a predetermined energy and ejected as ion packets to the ion flight unit 20.

[0057] The ion flight unit 20 includes a main electrode 21 , an ion introduction port 22 , an ion discharge port 23 , and a deflection electrode 24 . The ion flight unit 20 also includes a surround voltage application unit 28 for applying a predetermined voltage to the main electrode 21 and a deflection voltage application unit 29 for applying a predetermined voltage to the deflection electrode 24 .

[0058] The main electrode 21 includes an outer electrode 211 having a substantially spheroidal shape and an inner electrode 212 having a substantially spheroidal shape provided inside the outer electrode 211. Figure 1, a cross-sectional view (longitudinal cross-sectional view) of a plane including the Z axis, which is the rotation axis of the outer electrode 211 and the inner electrode 212 in a substantially rotating ellipsoid, and the X axis, which is an axis perpendicular to the Z axis, i.e., a ZX plane is shown. If the main electrode 21 is cut along a plane including the Z axis, the cross-sectional view is similar to the ZX plane regardless of the azimuth angle (rotation angle of the Z axis). Figure 1 The shape shown is roughly the same shape. Figure 2 , a top view viewed from the positive direction of the Z axis is shown. The axis perpendicular to the Z axis and the X axis is set as the Y axis, and the plane including the X axis and the Y axis is set as the XY plane.

[0059] The outer electrode 211 and the inner electrode 212 are composed of three groups of partial electrode pairs S1, S2 and S3 formed by making a pair of electrodes that are curved in the ZX plane face each other, and four groups of partial electrode pairs L1, L2, L3 and L4 formed by making a pair of electrodes that are straight in the ZX plane face each other. The partial electrode pair S2 is arranged at both ends of the main electrode 21 in the X direction in the ZX plane, and has a shape symmetrical with respect to the X-axis line. The partial electrode pair S1 is arranged on the positive side of the Z direction more than the partial electrode pair S2. The partial electrode pair S3 is arranged on the negative side of the Z direction more than the partial electrode pair S2, and is linearly symmetrical with the partial electrode pair S1 about the X-axis. The partial electrode pair L2 is arranged between the partial electrode pairs S1 and S2. The partial electrode pair L3 is arranged between the partial electrode pairs S2 and S3, and has a shape symmetrical with the partial electrode pair L2 about the X-axis line. The partial electrode pair L1 has a circular plate shape perpendicular to the Z axis and is arranged on the positive side of the Z direction and inside the partial electrode pair S1 in the XY plane. The partial electrode pair L4 also has a circular plate shape perpendicular to the Z axis and is arranged on the negative side of the Z direction in a manner symmetrical to the partial electrode pair L1 relative to the X axis.

[0060] By combining these partial electrode pairs, the outer electrode 211 and the inner electrode 212 each have a substantially spheroidal shape as a whole. The outer shape of the outer electrode 211 is, for example, 500 mm in the major axis direction (X direction, Y direction) and 300 mm in the minor axis direction (Z direction). In addition, for example, the interval between the outer electrode 211 and the inner electrode 212 is 20 mm. By reducing the overall size of the outer electrode 211 and the inner electrode 212, the overall miniaturization of the MT-TOF-MS1 can be achieved.

[0061] In the partial electrode pairs S1, S2, and S3 that are curved in the ZX plane, a potential is applied by the surrounding voltage application unit 28 to form an electric field from the outer electrode 211 toward the inner electrode 212. On the other hand, in the partial electrode pairs L1, L2, L3, and L4 that are linear in the ZX plane, the same potential is applied by the surrounding voltage application unit 28 to the outer electrode 211 and the inner electrode 212. Thus, a surrounding electric field that causes ions to orbit in the space between the outer electrode 211 and the inner electrode 212 is formed, and the orbital orbit 25 of the ions is defined in the inner space.

[0062] An ion introduction port 22 is provided in the partial electrode pair S1 in the outer electrode 211 for introducing ions ejected from the ion source 11 into the orbital orbit 25. The ion introduction port 22 is provided at a position slightly deviated from the X-axis to the positive side in the Y direction, and is configured so that ions are injected from the ion source 11 approximately parallel to the X-axis. At the position just after the ions are injected into the orbital orbit 25 from the ion introduction port 22, the ions are subjected to a centripetal force from the orbital electric field generated by the partial electrode pair S1. In addition, the ion introduction port 22 deviates from the X-axis to the positive side in the Y direction, thereby being subjected to a force in the direction of the X-axis. As a result, the ions orbit along the approximately elliptical orbital orbit 25, drifting in a manner that the orbital orbit moves (rotates) counterclockwise when viewed from the positive side in the Y direction each time they orbit, while moving in the orbital orbit 25 (refer to Figure 3 )Flying. Figure 3 In FIG. 2 , the orbital trajectory 25 of the ion is shown as a top view in the XY plane.

[0063] The deflection electrode 24 is provided on the orbital track 251 of the predetermined circle (nth circle). The deflection electrode 24 is a pair of plate-shaped electrodes, and is arranged at a position slightly away from the Z axis in the internal space of the partial electrode pair L4. The deflection electrode 24 is arranged at a position away from the Z axis to avoid interference between the deflection electrode 24 and the orbital tracks 25 other than the orbital track 251 of the nth circle. Figure 4 This is a ZX' cross-sectional view of the orbit 251 of the nth turn. The deflection electrode 24 is arranged to sandwich the orbit 251 in a manner that the surface is parallel to the ZX' plane. The detailed structure of the deflection electrode 24 will be described later. A predetermined deflection voltage is applied to the deflection electrode 24, and the drift direction of the ions is reversed by the deflection electric field formed thereby.

[0064] The ions whose drift direction is reversed in the orbit 251 of the nth circle, in each orbit, move in the direction ( Figure 3 The direction opposite to the direction shown by the solid line Figure 3 While drifting in the direction indicated by the dashed line, it is flying around orbit 25. Figure 3 The top view shows that the ions are flying in such a way that the trajectory of their flight so far returns to the original direction, but Figure 1The flight direction (clockwise) of the ions shown does not change. That is, since the ions heading toward the deflection electrode 24 and the ions deflected by the deflection electric field formed by the deflection electrode 24 fly in the same direction, they do not collide.

[0065] The partial electrode pair S3 is provided with an ion ejection port 23 . After orbiting the orbit 25 and being deflected by the deflection electric field to reverse the drift direction, the ions orbiting the orbit 25 again are ejected to the outside from the ion ejection port 23 and incident on the ion detector 12 .

[0066] Through the composition of the ion source 11, the main electrode 21 and the ion detector 12, a large number of ions with various mass-to-charge ratios emitted from the ion source 11 fly in a circular orbit 25 defined by the internal space of the main electrode 21 for a time (flight time) corresponding to the mass-to-charge ratio of each ion, are separated according to the mass-to-charge ratio and detected by the ion detector 12.

[0067] The MT-TOF-MS of this embodiment has a characteristic in the structure of the deflection electrode 24. Figure 5 As shown, the deflection electrode 24 is configured so that different voltages can be applied to the first area 241 (first partial electrode) in the center of the surface (opposing surface) and the second area 242 (surrounding part, side and back of the surface, second partial electrode) in addition. The electrode configured in this way can be configured using a printed circuit board (PCB) in which a plurality of electrodes are separated from each other (or arranged adjacently with an insulator interposed therebetween) on a ceramic substrate, for example.

[0068] A voltage (deflection voltage) that reverses the drift direction of the orbit 25 is applied to the first region 241. Specifically, a predetermined voltage of opposite polarity to that of the ions is applied to the first region 241 of the electrode disposed on the orbit 25 side of the n-1th turn in the deflection electrode 24, and a voltage of the same polarity as that of the ions (or grounding) is applied to the first region 241 of the other electrode. As a result, the ions flying on the orbit 251 of the nth turn are deflected to the orbit 25 side of the n-1th turn, and the drift direction is reversed. A voltage that forms the same electric field as the surrounding electric field, that is, the same voltage as that applied to the electrode L4, is applied to the second region 242.

[0069] In this embodiment, the deflection electrodes 24 are arranged opposite to each other so as to sandwich the inside of the electrode L4, that is, the portion where the ions fly in a straight line in the orbit 25. When the deflection electrodes 24 are arranged in the region where the ions fly in a straight line and where there is no potential gradient, the structure of the deflection electrodes 24 can be simplified by applying a certain voltage to the portion other than the first region 241.

[0070] Conventionally, in an MT-TOF-MS having a configuration for reversing the drift direction, a deflection voltage is applied to the entire deflection electrode. Figure 6As shown, when measuring positive ions, since a negative voltage is applied to the electrode located on the side of the orbit close to the n-1th circle and a positive voltage is applied to the entire electrode, the fringe electric field formed by the application of the deflection voltage not only deflects the ions flying in the nth orbit, but also deflects the ions flying in the adjacent n-1th orbit, so that the ions cannot be made to fly in the specified orbit.

[0071] In contrast, in the MT-TOF-MS of the present embodiment, Figure 7 As shown, a deflection voltage is applied only to the first region 241 in the central portion of the surface of the deflection electrode 24, and a surrounding voltage is applied to the second region 242 other than the deflection electrode 24. Thus, a deflection electric field is formed only in the portion of the n-th orbit 251. Thus, it is possible to suppress the undesired deflection of ions caused by the disturbance of the surrounding electric field defining the adjacent n-1-th orbit 25.

[0072] (2) Modification of MT-TOF-MS

[0073] The above embodiment is a configuration example and can be modified appropriately. In the above embodiment, the deflection electrode 24 is arranged at the position of the electrode L4, but the deflection electrode 26 may be arranged at other positions. Figure 8 As shown in FIG. 1 , a deflection electrode 26 may be arranged at the position of the electrode S2. However, an electric field that attracts ions from the outer electrode toward the inner electrode is formed at this position as a deflection electric field. Fig. 9 As shown, a deflection voltage is applied to the first region 261 of the electrode as in the above embodiment, and a voltage is applied to the second region 262 so as to form an electric field identical to the surrounding electric field. In this case, a plurality of electrodes may be arranged in the second region 262 and different voltages may be applied to each of them.

[0074] In the above embodiment, the ion introduction port 22 and the ion discharge port 23 are arranged on the same side in a plan view. Fig.10 As shown, the two are arranged on opposite sides sandwiching the Z axis, that is, the ion introduction port 22 is arranged on the negative side of the X axis (same as the above embodiment), and the ion discharge port 27 is arranged on the positive side of the X axis. In this case, the ion introduction port 22 and the ion discharge port 27 are both provided at the electrode S1.

[0075] Furthermore, the above-mentioned embodiment is an MT-TOF-MS configured to rotate the flight trajectory of ions successively by a specified angle during each orbit, but the same deflection electrodes as those in the above-mentioned embodiment can also be used in an MT-TOF-MS configured to displace the flight trajectory of ions successively by a certain amount in a specified direction during each orbit (for example, patent document 1).

[0076] (3) One embodiment of MR-TOF-MS

[0077] Fig.11 MR-TOF-MS3 of this embodiment is schematically shown. MR-TOF-MS3 of this embodiment has an ion source 31, an ion flight unit 40, and an ion detector 32. Fig.11 In order to illustrate the round trip trajectory of the ions in a manner that is easier to understand, the number of round trips shown is less than the actual number.

[0078] The ion source 31 includes, for example, an ionization unit for ionizing the sample and an ion trap for temporarily retaining the ions. Ions with various mass-to-charge ratios generated from the sample in the ionization unit are temporarily captured by the ion trap, cooled by a cooling gas, and then given a predetermined energy and ejected as an ion packet to the ion flight unit 40.

[0079] The ion flight unit 40 includes a back plate electrode 41 , a reflection electrode 42 , an ion introduction port 43 , an ion discharge port 44 , and a deflection electrode 45 . In addition, the ion flight unit 40 includes a reciprocating voltage application unit 48 for applying a predetermined voltage to the back plate electrode 41 and the reflection electrode 42 , and a deflection voltage application unit 49 for applying a predetermined voltage to the deflection electrode 45 .

[0080] like Fig.11 As shown, the back plate electrode 41 is a pair of plate-shaped electrodes disposed on the positive and negative sides of the Z direction with the ion flight space sandwiched therebetween. The reflective electrode 42 is composed of five rectangular frame-shaped electrodes, each disposed on the flight space side of the two back plate electrodes 41 . Fig.11 The configuration is an example, and the number of rectangular plate-shaped electrodes constituting the reflective electrode 42 may be 4 or less, or 6 or more.

[0081] The deflection electrode 45 is arranged at the end of the X direction on the opposite side of the side for ion introduction and discharge (the side where the ion source 31 and the ion detector 32 are arranged) with the flight space sandwiched therebetween. A predetermined voltage with the same polarity as the ions to be measured is applied to the back plate electrode 41 and the reflection electrode 42, respectively, to form a reciprocating electric field in which the potential increases toward the back plate electrode 41.

[0082] Ions are introduced into the flight space from the ion source 31 in a direction slightly inclined toward the X axis relative to the Z axis. The ions introduced into the flight space from the ion source 31 fly toward the back plate electrode 41 located on the positive side of the Z direction. As described above, since a reciprocating electric field whose potential becomes higher toward the back plate electrode 41 is formed in the space surrounded by the back plate electrode 41 and the reflecting electrode 42, the ions injected into the space are gradually decelerated, and then the flight direction of the ions is reversed to the negative side of the Z direction, and flies toward the back plate electrode 41 located on the negative side of the Z direction. In this way, the ions introduced into the flight space are injected into the space surrounded by the back plate electrode 41 and the reflecting electrode 42, so as to repeatedly fly in the reciprocating orbit 47 in which the flight path is reversed. In addition, the reciprocating orbit drifts toward the positive side of the X direction each time it goes back and forth.

[0083] The deflection electrode 45 is provided at a position on the X-axis of the predetermined (m-th) reciprocating track 471. The deflection electrode 45 is a pair of plate-shaped electrodes, and is disposed opposite to each other with the surfaces thereof being parallel to the YZ plane, sandwiching the m-th reciprocating track. The detailed structure of the deflection electrode 45 will be described later. A predetermined deflection voltage is applied to the deflection electrode 45, and the drift direction of the ions is reversed from the positive side of the X-direction to the negative side by the deflection electric field formed by the deflection voltage.

[0084] The ions whose drift direction is reversed in the nth round trip orbit 471 move in the same direction as the drift direction so far ( Fig.11 The direction opposite to the direction shown by the solid line Fig.11 The ion beam flies in a reciprocating orbit 47 while drifting in the direction indicated by the middle dotted line, and is emitted from the end of the flight space and injected into the ion detector 32.

[0085] In this way, by having a structure including a back plate electrode 41, a reflection electrode 42 and a deflection electrode 45, a large number of ions with various mass-to-charge ratios emitted from the ion source 31 fly in a round-trip orbit 47 defined by a flight space surrounded by the back plate electrode 41 and the reflection electrode 42 for a time (flight time) corresponding to the mass-to-charge ratio of each ion, thereby being separated according to the mass-to-charge ratio and detected by the ion detector 32.

[0086] The MR-TOF-MS3 of this embodiment is also characterized in the structure of the deflection electrode 45. Fig.12 As shown, the deflection electrode 45 is configured to apply different voltages to the first area 451 (first partial electrode) in the center of the surface facing the reciprocating track 471 and the second area 452 (the peripheral part, side and back of the surface, second partial electrode) other than the center part. Such an electrode can be configured using a printed circuit board (PCB), for example.

[0087] A voltage (deflection voltage) that reverses the drift direction of the round-trip track 47 is applied to the first region 451. Specifically, a predetermined voltage of a polarity opposite to that of the ions is applied to the first region 451 of the electrode disposed on the m-1th round-trip track 47 side of the deflection electrode 45, and a voltage of the same polarity as that of the ions is applied to the first region 451 of the other electrode. As a result, the ions flying on the m-1th round-trip track 471 are deflected to the m-1th round-trip track 47 side, and the drift direction is reversed. A voltage (grounded in this embodiment) that forms an electric field identical to the round-trip electric field is applied to the second region 452.

[0088] In this embodiment, the deflection electrodes 45 are arranged opposite to each other so as to sandwich the portion where the ions fly in a straight line between the two reflection electrodes 42, i.e., in the reciprocating track 47. When the deflection electrodes 45 are arranged in the region where there is no potential gradient where the ions fly in a straight line, the structure of the deflection electrodes 45 can be simplified by applying a certain voltage to the portion other than the first region 451.

[0089] In the past, in an MT-TOF-MS configured to reverse the drift direction, since a deflection voltage is applied to the entire deflection electrode, as in the case of the previous MT-TOF-MS, the fringe electric field formed by the application of the deflection voltage will not only deflect the ions flying in the mth round-trip orbit 471, but will also deflect the ions flying in the adjacent m-1th round-trip orbit 47, thereby preventing the ions from flying in the prescribed round-trip orbit.

[0090] In contrast, in the MT-TOF-MS of this embodiment, a deflection voltage is applied only to the first region 451 in the central portion of the surface of the deflection electrode 45, and a reciprocating voltage is applied to the second region 452 other than the deflection electrode 45. Thus, a deflection electric field is formed only in the portion of the m-th reciprocating orbit 471, and undesired deflection of ions flying in the adjacent m-1-th reciprocating orbit 47 can be suppressed.

[0091] (4) Modifications of MR-TOF-MS

[0092] The above embodiment is a configuration example and can be modified as appropriate. In the above embodiment, the deflection electrode 45 is arranged at the X-axis position at the positive end of the flight space in the X direction, but the deflection electrode 45 may be arranged at other positions.

[0093] For example, Fig.13 As shown, the deflection electrode 46 may be arranged in the space surrounded by the back plate electrode 41 and the reflection electrode 42. However, a reciprocating electric field is formed at this position, where the potential becomes higher toward the back plate electrode 41. Therefore, Fig.14The figure shows the voltage applied to the deflection electrode 46 located near the back plate electrode 41. The deflection voltage is applied to the first region 461 of the deflection electrode 46 in the same manner as in the above embodiment, and on the other hand, the voltage is applied to the second region 462 so as to form an electric field along the Z axis as in the round-trip electric field. In this case, a plurality of electrodes may be arranged in the second region 462 and different voltages may be applied to each of them.

[0094] In addition, in this modification, if a reciprocating orbit without displacement in the Y direction is used in the same manner as the MR-TOF-MS of the above-mentioned embodiment, the ions before the drift direction is reversed by the deflection electric field and the ions after the drift direction is reversed fly back and forth in the same reciprocating orbit, and there is a possibility that the two will collide. Therefore, when the deflection electrode 46 is used, when the ions are injected from the ion source 31 into the flight space, the ions are also introduced obliquely in the Y direction, such as Fig.13 As shown in the right figure, a voltage with the same polarity as the ions is applied to the reflective electrode 50 arranged on the Y axis, and it is repeatedly displaced on the positive and negative sides of the Y direction, using a reciprocating orbit that reciprocates in the YZ plane during each round trip.

[0095] (5) Another Modification

[0096] The present invention is not limited to the above-described embodiment and modified examples, and various modifications are possible.

[0097] In the above-described embodiments of the MT-TOF-MS and the MR-TOF-MS, deflection electrodes composed of a pair of plate-shaped electrodes are used as the deflection electrodes 24 , 26 , 45 , and 46 , but other configurations may also be employed.

[0098] For example Fig.15 The electrodes shown in the figure are provided with a set of plate-shaped electrodes in one of the two directions orthogonal to the orbit of the first predetermined circle or the orbit of the first predetermined round trip, and voltages V1 and -V1 are applied to form an electric field, and a set of split plate-shaped electrodes is also provided in the other direction, and voltages corresponding to the potential of the position of the split electrodes are applied to each split electrode. In addition, due to Fig.15 The configuration of the portion corresponding to the first region of the deflection electrode will be shown below, so only this portion is shown in the figure. Electrodes for applying a ring voltage or a round-trip voltage are appropriately added outside the portion constituting the first region.

[0099] Fig.16 The electrodes shown are arranged in two directions orthogonal to the orbit of the first predetermined circle or the first predetermined round trip orbit, respectively, and voltages V1 and -V1 are applied to one set of plate electrodes, and voltages V2 and -V2 are applied to the other set of electrodes. Fig.16 The electrodes can deflect the ions by setting a deflection electric field formed by potential differences of equal or different magnitudes in two directions.

[0100] Fig.17 The electrode shown in the figure is arranged in a manner that 12 rod electrodes are arranged around a predetermined orbit or a predetermined round trip orbit, and different voltages are applied to each of them. Fig.16 Similarly, the electrodes can deflect ions by setting a deflection electric field formed by potential differences of equal or different magnitudes in two directions.

[0101] Furthermore, although the example of using an elliptical orbital track in the MT-TOF-MS of the above embodiment has been described, the same configuration as that of the above embodiment can be adopted in other MT-TOF-MS using orbital tracks of various shapes such as a circle and an 8-shaped track.

[0102] Furthermore, in the MT-TOF-MS of the above-mentioned embodiment and modified example, the ion inlet and the ion ejection outlet are arranged on the outer electrode, the ions are linearly injected into the orbit, and the ions are linearly ejected from the orbit. However, as long as an appropriate deflection electrode is configured, the ion inlet and the ion ejection outlet can also be arranged on the inner electrode.

[0103] [plan]

[0104] Those skilled in the art will appreciate that the above-mentioned multiple exemplary embodiments are specific examples of the following schemes.

[0105] (Item 1)

[0106] A time-of-flight mass spectrometer according to one embodiment comprises:

[0107] The orbit defining electrode is an electrode for forming an orbiting electric field for defining an orbit in which ions are repeatedly orbited while drifting in a predetermined direction each time, and includes an outer electrode arranged on the outer side of the orbit and an inner electrode arranged on the inner side of the orbit;

[0108] An ion introduction port for introducing ions into the orbit;

[0109] an ion ejection port for ejecting ions from the orbit;

[0110] A surrounding voltage applying unit applies surrounding voltages to the outer electrode and the inner electrode respectively to form the surrounding electric field;

[0111] a set of deflection electrodes disposed opposite to each other with the first predetermined orbit of the orbit sandwiched therebetween, and comprising a first partial electrode facing the first predetermined orbit and a second partial electrode constituting a portion other than the first partial electrode;

[0112] The voltage applying unit applies a deflection voltage for reversing the drift direction of ions flying in the predetermined orbit to the first partial electrode, and applies a voltage for forming the orbiting electric field to the second partial electrode.

[0113] The time-of-flight mass spectrometer of the first item is a multi-circle time-of-flight mass spectrometer (MT-TOF-MS) with an open orbit (quasi-closed orbit). In this mass spectrometer, a predetermined orbital voltage is applied to the outer electrode and the inner electrode constituting the orbital defining electrode to form an orbital electric field for defining the orbital orbit in which the ions fly. Ions are introduced into the orbital orbit from the ion introduction port, and fly in the orbital orbit while drifting in a predetermined direction at each orbit. In the orbital orbit of the first predetermined circle in the orbital orbit, a group of deflection electrodes is arranged to sandwich the orbital orbit. The deflection electrode has a first partial electrode facing the orbital orbit of the first predetermined circle and a second partial electrode constituting a portion other than the first partial electrode. By applying a deflection voltage to the first partial electrode, the drift direction of the ions flying in the orbit is reversed. At this time, the deflection voltage is applied only to the first partial electrode facing the orbital orbit of the first predetermined circle in the deflection electrode, and a voltage for forming the orbital electric field is applied to the second partial electrode constituting the portion other than the first partial electrode. Since a deflection voltage is applied to the entire deflection electrode in the previous MT-TOF-MS, a deflection electric field is formed in a wider range around the deflection electrode, so that ions flying in the orbit adjacent to the orbit of the first predetermined circle are also deflected. In the MT-TOF-MS of the first item, since the orbiting electric field is formed in the second part of the electrode outside the part facing the orbit of the first predetermined circle, it is possible to suppress the unexpected deflection of ions caused by the disorder of the orbiting electric field in the orbit adjacent to the orbit of the first predetermined circle.

[0114] (Item 2)

[0115] In the time-of-flight mass spectrometer according to item 1,

[0116] The deflection electrodes are disposed opposite to each other with a portion of the orbital track where ions fly in a straight line being sandwiched therebetween.

[0117] In the time-of-flight mass spectrometer described in item 2, since the deflection electrode is arranged in the part where ions fly in a straight line and in an area where there is no potential gradient in the flight space of the ions, it is only necessary to apply a certain voltage to the second partial electrode constituting the part other than the orbital part facing the specified circle, thereby simplifying the structure of the deflection electrode.

[0118] (Item 3)

[0119] In the time-of-flight mass spectrometer according to item 1 or 2,

[0120] The deflection electrodes are a pair of plate-shaped electrodes.

[0121] The first partial electrode forms a central region of a surface facing the orbital track.

[0122] In the time-of-flight mass spectrometer described in item 3, since the area where the deflection voltage is applied is limited to the center area of ​​the surface facing the orbit, the undesired deflection of ions flying in orbits other than the predetermined orbit can be more reliably suppressed.

[0123] (Item 4)

[0124] In addition, another aspect of the time-of-flight mass spectrometer comprises:

[0125] The reciprocating trajectory defining electrode is an electrode that forms a reciprocating electric field for defining a reciprocating trajectory in which the ions drift in a predetermined direction each time, and includes a set of reflecting electrodes disposed on both sides of the flight space of the ions.

[0126] An ion introduction port for introducing ions into the reciprocating track;

[0127] An ion discharge port for discharging ions from the round-trip track;

[0128] A reciprocating voltage applying unit, applying a reciprocating voltage to each of the group of reflective electrodes to form the reciprocating electric field;

[0129] a set of deflection electrodes disposed opposite to each other with a predetermined first reciprocating track sandwiched therebetween, and comprising a first partial electrode facing the predetermined first reciprocating track and a second partial electrode constituting a portion other than the first partial electrode;

[0130] The voltage applying unit applies a deflection voltage for reversing the drift direction of ions flying in the predetermined round-trip orbit to the first partial electrode, and applies a voltage for forming the round-trip electric field to the second partial electrode.

[0131] The time-of-flight mass spectrometer of the fourth item is a multiple reflection time-of-flight mass spectrometer (MR-TOF-MS). In this mass spectrometer, a predetermined reciprocating voltage is applied to a group of reflection electrodes arranged on both sides of the flight space of the ions, thereby forming a reciprocating electric field for defining the reciprocating orbit in which the ions fly. The ions are introduced into the reciprocating orbit from the ion introduction port, and fly in the reciprocating orbit while drifting in a predetermined direction each time they go back and forth. In the predetermined reciprocating orbit among the reciprocating orbits, a group of deflection electrodes is arranged to sandwich the reciprocating orbit. The deflection electrode has a first partial electrode facing the predetermined reciprocating orbit and a second partial electrode constituting a portion other than the first partial electrode. By applying a deflection voltage to the first partial electrode, the drift direction of the ions flying in the orbit is reversed. At this time, the deflection voltage is applied only to the first partial electrode facing the predetermined reciprocating orbit among the deflection electrodes, and a voltage for forming a reciprocating electric field is applied to the second partial electrode constituting the portion other than the first partial electrode. In the MR-TOF-MS of item 4, since a reciprocating electric field is formed in the second part of the electrode other than the part facing the predetermined reciprocating orbit, it is possible to suppress the undesired deflection of ions caused by the disorder of the reciprocating electric field of the reciprocating orbit adjacent to the predetermined reciprocating orbit.

[0132] (Item 5)

[0133] In the time-of-flight mass spectrometer described in item 4,

[0134] The deflection electrodes are disposed opposite to each other with a portion of the reciprocating orbit where ions fly in a straight line being sandwiched therebetween.

[0135] In the time-of-flight mass spectrometer described in Item 5, since the deflection electrode is arranged in the portion where ions fly in a straight line and in an area where there is no potential gradient in the flight space of the ions, it is only necessary to apply a certain voltage to the second partial electrode constituting the portion other than the portion facing the specified round-trip orbit, thereby simplifying the structure of the deflection electrode.

[0136] (Item 6)

[0137] In the time-of-flight mass spectrometer described in item 4 or 5,

[0138] The deflection electrodes are a pair of plate-shaped electrodes.

[0139] The first partial electrode forms a region at the center of a surface facing the reciprocating track.

[0140] In the time-of-flight mass spectrometer described in item 6, since the area to which the deflection voltage is applied is limited to the center area of ​​the surface facing the round-trip orbit, it is possible to more reliably suppress the undesired deflection of ions flying in round-trip orbits other than the predetermined round-trip orbit.

[0141] Description of Reference Numerals

[0142] 1 Multi-surface time-of-flight mass spectrometer (MT-TOF-MS)

[0143] 11. Ion Source

[0144] 12 Ion detector

[0145] 20 Ion Flight Department

[0146] 21 Main electrode

[0147] 211 Outer electrode

[0148] 212 Medial Electrode

[0149] 22 Ion introduction port

[0150] 23, 27 Ion Exhaust Port

[0151] 24, 26 Deflection electrodes

[0152] 241, 261 Area 1

[0153] 242, 262 Area 2

[0154] 25 Orbit

[0155] 251 The nth orbit

[0156] 28 Surrounding voltage applying section

[0157] 29 Deflection voltage applying section

[0158] 3 Multiple reflection time-of-flight mass spectrometer (MR-TOF-MS) 31 Ion source

[0159] 32 Ion detector

[0160] 40 Ion Flight Department

[0161] 41 Back plate electrode

[0162] 42 Reflective electrode

[0163] 43 Ion introduction port

[0164] 44 Ion Exhaust Port

[0165] 45, 46 Deflection electrodes

[0166] 451, 461 Area 1

[0167] 452, 462 Area 2

[0168] 47 Round Trip Track

[0169] 471 The mth round trip orbit

[0170] 50 Reflection electrode

[0171] 48 Round trip voltage applying unit

[0172] 49: Deflection voltage applying section.

Claims

1. A time-of-flight mass spectrometer, It is characterized in that have: The orbit defining electrode is an electrode for forming an orbiting electric field for defining an orbit in which ions are repeatedly orbited while drifting in a predetermined direction each time, and includes an outer electrode arranged on the outer side of the orbit and an inner electrode arranged on the inner side of the orbit; An ion introduction port for introducing ions into the orbit; an ion ejection port for ejecting ions from the orbit; A surrounding voltage applying unit applies surrounding voltages to the outer electrode and the inner electrode respectively to form the surrounding electric field; a set of deflection electrodes disposed opposite to each other with the first predetermined orbit of the orbit sandwiched therebetween, and comprising a first partial electrode facing the first predetermined orbit and a second partial electrode constituting a portion other than the first partial electrode; The voltage applying unit applies a deflection voltage for reversing the drift direction of ions flying in the predetermined orbit to the first partial electrode, and applies a voltage for forming the orbiting electric field to the second partial electrode.

2. The time-of-flight mass spectrometer according to claim 1, It is characterized in that The deflection electrodes are disposed opposite to each other with a portion of the orbit in which the ions fly in a straight line being sandwiched therebetween.

3. The time-of-flight mass spectrometer according to claim 1, It is characterized in that The deflection electrodes are a pair of plate-shaped electrodes. The first partial electrode forms a region facing the center of the surface of the orbiting track.

4. A time-of-flight mass spectrometer, It is characterized in that have: The reciprocating trajectory defining electrode is an electrode that forms a reciprocating electric field for defining a reciprocating trajectory in which the ions drift in a predetermined direction each time, and includes a set of reflecting electrodes disposed on both sides of the flight space of the ions. An ion introduction port for introducing ions into the reciprocating track; An ion discharge port for discharging ions from the round-trip track; A reciprocating voltage applying unit, applying a reciprocating voltage to each of the group of reflective electrodes to form the reciprocating electric field; a set of deflection electrodes disposed opposite to each other with a predetermined first reciprocating track sandwiched therebetween, and comprising a first partial electrode facing the predetermined first reciprocating track and a second partial electrode constituting a portion other than the first partial electrode; The voltage applying unit applies a deflection voltage to the first partial electrode for reversing the drift direction of ions flying in the predetermined round-trip orbit, and applies a voltage to the second partial electrode for forming a round-trip electric field of a round-trip orbit adjacent to the predetermined round-trip orbit.

5. The time-of-flight mass spectrometer according to claim 4, It is characterized in that The deflection electrodes are disposed opposite to each other with a portion of the reciprocating orbit where ions fly in a straight line being sandwiched therebetween.

6. The time-of-flight mass spectrometer according to claim 4, It is characterized in that The deflection electrodes are a pair of plate-shaped electrodes. The first partial electrode forms a region at the center of a surface facing the reciprocating track.

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