JP4940977B2 - Ion deflection apparatus and mass spectrometer - Google Patents

Description

  The present invention relates to an ion deflector used in a mass spectrometer and the like, and a mass spectrometer using the ion deflector as an ion transport optical system.

  FIG. 11 is a schematic block diagram of a general mass spectrometer. The ion source unit 50 ionizes various components contained in the sample, and the generated ions are transported by the ion transport unit 51 and introduced into the mass separation unit 52. The mass separator 52 separates the introduced ions according to the mass (strictly, the mass to charge ratio m / z), and the ion detector 53 detects the separated ions and outputs a detection signal. Since the mass separation unit 52 and the ion detection unit 53 are disposed in a high vacuum atmosphere, the ion source unit 50 is in a substantially atmospheric pressure atmosphere like an ICP (inductively coupled plasma) ion source or an ESI (electrospray) ion source. In the case where ionization is performed, the ion transport part 51 carries ions under a low vacuum atmosphere with a relatively low degree of vacuum (high gas pressure) between the ion source part 50 and the mass separation part 52. become.

  In the mass spectrometer, when the ions generated by the ion source unit 50 are introduced into the ion transport unit 51, neutral molecules or light may be simultaneously introduced in addition to the target ions. For example, in a configuration using an ICP ion source, neutral molecules due to plasma light, plasma gas, residual gas, and the like are easily introduced into the ion transport portion 51. In the configuration using the ESI ion source, neutral molecules resulting from the sample solvent sprayed in the ionization chamber are easily introduced into the ion transport portion 51. Since light and neutral molecules are not excluded by the mass separation unit 52, when light or neutral molecules that have passed through the mass analysis unit 52 reach the ion detection unit 53, the mass spectrum is obtained. It becomes the background noise above. Further, when neutral molecules are introduced into the ion transport part 51 or the mass separation part 52, they may adhere to the electrodes constituting them as a contamination, which may contribute to destabilizing the operation of the apparatus.

  Conventionally, an ion optical system called off-axis is used in the ion transport part 51 in order to remove unwanted light, neutral molecules and the like as described above in a mass spectrometer. The off-axis ion optical system is an optical system devised so that the incident ion optical axis Ci and the outgoing ion optical axis Co are not arranged in a straight line, and can be roughly classified as shown in FIG. The configuration in which the ion optical axis Ci and the outgoing ion optical axis Co are obliquely crossed (including orthogonal), and the incident ion optical axis Ci and the outgoing ion optical axis Co are shifted in parallel as shown in FIG. Such a configuration can be considered. In any case, the off-axis ion optical system uses an ion deflecting device that bends the orbit of incident ions by the action of an electric field (or magnetic field), that is, deflects the traveling direction of the ions. Since light and neutral molecules are not affected by an electric field or magnetic field, they go straight along the incident ion optical axis Ci and diverge or disappear in the middle, and are not introduced into the subsequent mass separation unit 52.

  Conventionally, various configurations have been proposed as an off-axis ion optical system. Some of these will be briefly described with reference to FIGS.

(1) Axis-shifted electrostatic lens FIG. 13 is a schematic diagram showing an example of the configuration of an axis-shifted ion optical system using an electrostatic lens. Ions that have passed through the orifice at the top of the skimmer 60 are introduced into an electrostatic field (DC electric field) formed by a parallel plate type electrostatic lens 61. The electrostatic field is obtained by superimposing the ion deflecting electrostatic field on the ion focusing electrostatic field, thereby deflecting the ions while converging them to the rear focal point, and shifting the incident ion optical axis Ci and the outgoing ion optical axis Co. Yes.

(2) Q Deflector FIG. 14 is a schematic diagram of a quadrupole electrostatic deflecting device called a Q deflector (see Patent Document 1). The Q deflector 62 is composed of four rod electrodes 621, 622, 623, 624 arranged in parallel to each other so as to extend in a direction orthogonal to the paper surface in the figure, and each rod electrode 621, 622, 623, 624. DC voltages V _d1 , V _d2 , V _d3 , and V _d4 are respectively applied to. When positive ions are to be analyzed, the DC voltage V _d3 applied to the third rod electrode 623 is set to a value larger than the other DC voltages V _d1 , V _d2 , and V _d4 , and as shown in FIG. Thus, an electrostatic field having an action of pushing ions in the direction from the third rod electrode 623 toward the first rod electrode 621 is formed. As a result, ions that have entered along the incident ion optical axis Ci are bent by approximately 90 ° in the direction of travel within the paper surface, and are emitted along the outgoing ion optical axis Co. On the other hand, since light and neutral particles are not affected by the electrostatic field, they go straight and are removed.

(3) Ion Mirror FIG. 15 is a schematic diagram of an ion mirror described in Patent Document 2 and the like. In the ion mirror, a ring electrode 63 is arranged in a plane inclined by approximately 45 ° with respect to the incident ion optical axis Ci, and a predetermined DC voltage _Vd is applied to the ring electrode 63. Ions incident along the incident ion optical axis Ci are reflected by the DC electric field formed by the ring-shaped electrode 63, and the trajectory thereof is bent by approximately 90 ° and emitted along the outgoing ion optical axis Co. On the other hand, since light and neutral particles are not affected by the electrostatic field, they pass through the opening of the ring electrode 63 and are removed.

(4) Multipole type high-frequency ion guide FIG. 16 is a schematic configuration diagram of an off-axis high-frequency ion guide using a rod electrode that extends straight (see, for example, Patent Document 3). The high-frequency ion guide 64 has a configuration in which a plurality of (for example, four) cylindrical rod electrodes 641 are arranged in parallel and symmetrically around the central axis, and the central axis (optical axis) of the ion guide 64 and the ion source. The optical axis of ions emitted from the unit 50 (incident ion optical axis Ci) is arranged so as to intersect at an appropriate angle. A high-frequency voltage having the same phase and the same amplitude is applied to the rod electrodes 641 facing each other across the central axis, and a high-frequency voltage having the same amplitude and the same phase is applied to the rod electrodes 641 adjacent in the circumferential direction. The ions emitted from the ion source unit 50 and introduced into the high-frequency ion guide 64 are constrained by the high-frequency electric field formed by the high-frequency voltage applied to the rod electrode 641 as described above, and vibrate while vibrating. Proceed along the axis. After exiting the ion guide 64, the ion guide 64 is introduced into the mass separator 52 along the outgoing ion optical axis Co.

  FIG. 17 is a schematic configuration diagram of an off-axis high-frequency ion guide 65 using a rod electrode 651 that is bent in the longitudinal direction (see, for example, Patent Document 4). That is, in the high-frequency ion guide 65, the central axis (optical axis) in the first half and the central axis (optical axis) in the second half are shifted in parallel, and the optical axis in the first half coincides with the incident ion optical axis Ci. The optical axis in the second half is coincident with the outgoing ion optical axis Co. While ions travel while being constrained by a high-frequency electric field formed by a high-frequency voltage applied to the rod electrode 651, the ions move obliquely so as to move from the first optical axis to the second optical axis, thereby being parallel. A large axis shift is achieved.

FIG. 18 (a) shows a case where the rod electrode is divided into a plurality of segments (segmented) in the longitudinal direction instead of using the bent rod electrode in order to achieve the parallel axis shift similar to FIG. FIG. 18B is a schematic cross-sectional view taken along the line AA ′, and FIG. 18C is a cross-sectional view taken along the line BB ′. (See Patent Document 5 etc.). In this example, one rod electrode is divided into 6 segments, and the small rod electrodes 71 of the two segments on the incident end side and the two segments on the output end side have a normal segment as shown in FIG. A high frequency voltage ± V _q · cos ωt for forming a quadrupole electric field is applied. That is, the high frequency voltage + V _q · cos ωt is applied to the pair of small rod electrodes 711 and 713 facing each other, and the high frequency voltage −V _q · cos ω t is applied to the other pair of small rod electrodes 712 and 714 facing each other. The

On the other hand, as shown in FIG. 18C, the small rod electrodes 72 of the two central segments are reversed at the same frequency to the upper and lower small rod electrodes 721 and 713 in addition to the high frequency voltage ± V _q · cos ωt. High-frequency voltages V _d1 · cos ωt and −V _d2 · cos ωt having different phases and amplitudes are superimposed and applied. As a result, in the space surrounded by the small rod electrodes 72 of the two central segments, a force that greatly oscillates in the plane including the two ion optical axes Ci and Co acts while constraining the ions. It is possible to shift from the optical axis Ci to the outgoing ion optical axis Co.

  As described above, although various off-axis ion optical systems have been proposed in the past, they are always satisfactory in a low vacuum atmosphere disposed between a substantially atmospheric pressure atmosphere and a high vacuum atmosphere. Performance cannot be obtained. That is, in such a low vacuum atmosphere, since the density of residual gas molecules is relatively high, the transported ions frequently collide and scatter with gas molecules. When the conventional electrostatic lens, Q deflector, or ion mirror as described above is used, it is difficult to capture ions whose trajectory is greatly deviated from the ion optical axis due to collision with gas molecules. Loss is large and ion transport efficiency tends to be low. As a result, the amount of ions introduced into the mass separator 52 is reduced, making it difficult to increase the analysis sensitivity.

  On the other hand, in the off-axis high-frequency ion guide, ions are relatively restrained by a high-frequency electric field, so that dissipation of ions deviating from the orbit due to collision with gas molecules can be suppressed. However, in a configuration using a straight rod electrode, the rod electrode must be lengthened in order to increase the amount of axis shift in order to increase the removal efficiency of light and neutral particles. For this reason, the size of the apparatus is increased, which is disadvantageous for miniaturization. In addition, in the configuration using the bent rod electrode or the segmented rod electrode, there is a problem that the electrode shape and the electrode holding structure are complicated and the cost is high.

US Pat. No. 6,630,665 US Pat. No. 6,661,021 US Pat. No. 5,672,868 US Pat. No. 6,762,407 US Pat. No. 6,730,904

  The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to achieve high transport efficiency even in a low vacuum atmosphere, and to greatly shift the ion optical axis with a compact structure. It is to provide an ion deflection apparatus capable of performing the following. Another object of the present invention is to provide a mass spectrometer capable of performing high-sensitivity and high-accuracy mass analysis using such an ion deflection apparatus.

The present invention made to solve the above problems is an ion deflection apparatus that changes the traveling direction of ions by the action of an electric field,
a) A surface including two or more rod electrodes arranged in parallel to each other so as to surround a straight line, and including a surface including two rod electrodes adjacent to each other around the straight line is defined as an ion incident surface. An electrode portion including two rod electrodes adjacent to each other and having an ion exit surface different from the ion entrance surface;
b) A high-frequency electric field that applies a force to the ions so as to keep the ions incident on the space in the space surrounded by the plurality of rod electrodes of the electrode part, and across the ion incident surface in the space A DC voltage and a high frequency applied to each of the plurality of rod electrodes to form a DC electric field that applies a force to the ions to bend the trajectory of the ions so that the incident ions exit the ion exit surface. Voltage application means for applying a voltage superimposed with the voltage;
The ions incident on the space surrounded by the plurality of rod electrodes from the ion incident surface are restrained by vibrating by the action of the high-frequency electric field, and the traveling direction is bent by the action of the DC electric field. It is made to radiate | emit from the said ion emission surface .

  The number of rod electrodes is not limited as long as the number is three or more. However, as one aspect, the electrode portion is composed of three or four rod electrodes arranged on three or four sides of a rectangular parallelepiped. It can be.

  Further, at least one DC voltage applied to each rod electrode may be a voltage that is larger or smaller than the others. Thus, it is possible to form a DC electric field that applies to the ions a force that bends the ions in a plane orthogonal to the extending direction of the rod electrode (the linear extending direction). On the other hand, in order to restrain ions to remain in the space, for example, a high-frequency voltage having the same amplitude, the same frequency, and the same phase is applied to two rod electrodes facing each other across the space, and adjacent rod electrodes are applied to the adjacent rod electrodes. It is preferable to apply a high-frequency voltage having the same amplitude and the same frequency and whose phases are reversed from each other.

  When ions enter the space surrounded by the rod electrode across the ion incident surface (typically in the orthogonal direction), the ions bend their orbits by the DC electric field while being constrained by the high frequency electric field, and the ions are emitted. Progress toward the surface. In a low vacuum atmosphere, ions often collide with residual gas molecules, and the trajectory of the ions changes due to the collision, but the direction of ion movement is corrected because it is constrained by a high-frequency electric field and bent in space. It is easy to gather around the ion optical axis. Therefore, ions are unlikely to diverge on the way, and ions can be emitted from the ion emission surface with high transport efficiency.

  However, the above high-frequency electric field has no ion binding action in the rod electrode stretching direction, so if the ions change their trajectory in the rod electrode stretching direction due to collision with residual gas molecules, the ions will diverge. Even if it comes out from the ion emission surface, it may not be used (it will not be accepted later).

  Therefore, as a preferred aspect of the present invention, the electrode unit further includes an auxiliary electrode disposed so as to sandwich a space surrounded by the plurality of rod electrodes from open end surfaces on both sides thereof, and the voltage applying unit includes It is preferable that a DC voltage that forms a DC electric field for preventing ions in the space to diverge in the linear extending direction is applied to the auxiliary electrode.

  In this configuration, the auxiliary electrode can be, for example, a rod-shaped electrode extending in a direction orthogonal to the straight line, or a flat electrode extending in a direction orthogonal to the straight line. If such an auxiliary electrode is provided, the ion transport efficiency can be further improved.

  In addition, the ion deflection apparatus according to the present invention can be used even in a high vacuum atmosphere, but is particularly useful in a low vacuum atmosphere. Therefore, a mass spectrometer according to the present invention includes an ion source that ionizes a target component under an atmospheric pressure atmosphere, a mass analysis unit that separates and detects ions according to mass in a high vacuum atmosphere, and the ion source. An ion transport unit that transports the generated ions to the mass spectrometer in a low vacuum atmosphere, and the ion deflector according to the invention is used as an off-axis ion transport optical system in the ion transport unit It is said.

  According to the ion deflection apparatus of the present invention, ions can be largely deflected while maintaining high ion transport efficiency even in a low vacuum atmosphere with many residual gas molecules. Thereby, the light and neutral particles introduced together with the ions can be removed, and these can be prevented from being introduced later. In addition, since ions are deflected in a direction orthogonal or oblique to the extending direction of the rod electrode, it is not necessary to increase the size of the apparatus itself in order to increase the deflection amount, that is, the amount of axis shift. Therefore, it is advantageous for downsizing of the apparatus, and removal of light and neutral particles can be more reliably performed by increasing the amount of axis shift. Further, the structure of the rod electrode is not complicated, and an increase in cost can be suppressed.

  Further, according to the mass spectrometer according to the present invention, it is possible to reliably remove the light and neutral particles generated in the ion source in the substantially atmospheric pressure atmosphere by the ion transport part and prevent this from entering the mass separation part. it can. Thereby, the background noise of the mass spectrum can be reduced, and contamination of the electrodes of the mass separation unit can be reduced.

  An embodiment of an ion deflector according to the present invention and a mass spectrometer using the ion deflector will be described with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic configuration diagram of an ICP mass spectrometer equipped with an ion transport optical system according to one embodiment (first embodiment) of an ion deflection apparatus according to the present invention, and FIG. 2 is a schematic configuration of an ion transport optical system according to this embodiment. 3 is a top view of the electrode portion of the ion transport optical system, and FIG. 4 is a perspective view of the electrode portion of the ion transport optical system.

  In this ICP mass spectrometer, ions generated in the plasma flame generated by the plasma torch 2 that is an ion source section are introduced into the first intermediate vacuum chamber 5 through the sampling cone 3 and further through the skimmer 4 to the second. It is introduced into the intermediate vacuum chamber 6. An ion transport optical system 1 for deflection, which will be described later, is disposed in the second intermediate vacuum chamber 6, and the ion traveling direction is greatly bent (approximately 90 ° angle) when passing through the ion transport optical system 1. Ions are emitted along the outgoing ion optical axis Co substantially orthogonal to the ion optical axis Ci and introduced into the subsequent high vacuum chamber 7. On the other hand, light derived from the plasma flame, neutral particles, and the like travel straight through the ion transport optical system 1 and are not introduced into the high vacuum chamber 7. In the high vacuum chamber 7, a quadrupole mass filter 8 and an ion detector 9 are disposed as a mass separation unit, and only ions having a specific mass selectively pass through the quadrupole mass filter 8. Then, it reaches the ion detector 9 and is detected.

  In the above configuration, the plasma torch 2 is installed in a substantially atmospheric pressure atmosphere, and the inside of the high vacuum chamber 7 is maintained in a high vacuum atmosphere by a vacuum pump such as a turbo molecular pump. The first intermediate vacuum chamber 5 and the second intermediate vacuum chamber 6 positioned between the two are also evacuated by a vacuum pump (not shown) so that the degree of vacuum gradually increases toward the high vacuum chamber 7. .

Next, the ion transport optical system 1 will be described in detail with reference to FIGS. The ion transport optical system 1 has a configuration in which four columnar (or cylindrical) rod electrodes 11, 12, 13, and 14 are arranged along four parallel sides of a rectangular parallelepiped. Here, it arrange | positions so that it may extend | stretch in the x-axis direction among the three axes of x, y, z orthogonal to each other. In the ion transport optical system 1, the ion incident surface Pi is set so as to include the first rod electrode 11 and the second rod electrode 12 adjacent thereto, and the first rod electrode 11 and the other second rod electrode adjacent thereto are set. The ion emission surface Po is set so as to include the four rod electrodes 14. Therefore, the ion incident surface Pi is on the x-axis / y-axis plane, the ion exit surface Po is on the x-axis / z-axis plane, and they are orthogonal to each other. Here, it is assumed that ions are incident so as to be orthogonal to the ion incident surface Pi. That is, the incident ion optical axis Ci is set in the z-axis direction and is orthogonal to the ion incident surface Pi. On the other hand, the exit ion optical axis Co is set in the y-axis direction, and ions are emitted so as to be orthogonal to the ion exit surface Po.

The first rod electrode 11 has a voltage V _d1 + V _{RF obtained} by adding the DC voltage V _d1 generated by the first DC voltage source 31 and the high frequency voltage V _RF · cos ωt generated by the high frequency voltage source 40 by the adder 21. The third rod electrode 13 to which cos ωt is applied and disposed opposite to the third rod electrode 13 has a DC voltage V _d3 generated by the third DC voltage source 33 and a high frequency voltage V _RF · cos ωt generated by the high frequency voltage source 40. Is added by the adder 23, and a voltage V _d3 + V _RF · cos ωt is applied. Further, the second rod electrode 12 has a DC voltage V _d2 generated by the second DC voltage source 32 and a high-frequency voltage V _RF · cos ωt generated by the high-frequency voltage source 40 in opposite phases (the phase is inverted by 180 °). A voltage V _d2 −V _RF · cos ωt obtained by adding the high frequency voltage −V _RF · cos ωt by the adder 22 is applied, and the fourth DC electrode 34 is connected to the fourth rod electrode 14 disposed opposite thereto. A voltage V _d4 −V _RF · cos ωt obtained by adding the generated DC voltage V _d4 and the high-frequency voltage −V _RF · cos ωt by the adder 24 is applied. The first to fourth DC voltage sources 31, 32, 33, and 34 and the high frequency voltage source 40 are connected to the control unit 41, and the amplitude of each DC voltage and the amplitude and frequency of the high frequency voltage are set by the control unit 41. The

Specifically, the first and second rod electrodes 11 and 12 sandwiching the ion incident surface Pi are configured so that ions arriving along the incident ion optical axis Ci can enter the space surrounded by the rod electrodes 11 to 14. Appropriate DC voltages V _d1 and V _d2 are applied. Accordingly, the values of the DC voltages V _d1 and V _d2 are determined depending on the value of the DC voltage applied to the preceding skimmer 4 and the like. Further, the relationship between the DC voltages V _d1 , V _d2 , V _d3 , and V _d4 applied to the four rod electrodes 11 to 14 is such that ions incident from the ion incident surface Pi exit from the ion output surface Po. Is set to form a DC electric field that applies a force to the ions that bends the trajectory of the ions substantially at right angles. Therefore, the value of the applied DC voltage differs depending on the polarity of ions to be analyzed and the magnitude of kinetic energy that the ions have when entering the space surrounded by the rod electrodes 11-14.

When positive ions are to be analyzed, the DC voltage V _d3 applied to the third rod electrode 13 is changed to DC voltages V _d1 , V _d2 applied to the first, second and fourth rod electrodes 11, 12, 14. It is made larger than _Vd4 . On the other hand, in case of analyzing negative ions, a DC voltage _{V d3} applied to the third rod electrode 13 first, the DC voltage _V d1, V applied to the second and fourth rod electrodes 11, 12, 14 _It is made smaller than _d2 and _Vd4 . Further, the DC voltages V _d1 , V _d2 , V _d3 , and V _d4 are adjusted according to the kinetic energy of the ions to be analyzed so that the ions follow a desired bending trajectory. Due to the action of the DC electric field formed by such a DC voltage, it is possible to bend the ions substantially at a right angle.

However, the degree of vacuum of the second intermediate vacuum chamber 6 in which the ion transport optical system 1 is disposed is not higher than that of the high vacuum chamber 7, and there are many opportunities for ions to collide with the residual gas because the residual gas is relatively large. . When such a collision occurs, the ions change their trajectories, causing the ions to dissipate. Therefore, in this ion transport optical system 1, the high-frequency voltage V _RF · cosωt or −V _{RF is} applied to each rod electrode 11-14 as described above so that ions can be pushed as close to the center of the space surrounded by the rod electrodes 11-14 as much as possible.・ Cos ωt is applied. Thereby, a high frequency electric field is formed in the space surrounded by the rod electrodes 11 to 14 so as to be superimposed on the DC electric field, and ions vibrate within a predetermined region by the action of the high frequency electric field. By appropriately determining the amplitude and frequency of the high-frequency voltage, the ions travel along the deflection trajectory bent almost at right angles as described above while vibrating.

  That is, the ions incident on the space surrounded by the four rod electrodes 11 to 14 across the ion incident surface Pi substantially perpendicularly are bent by the DC electric field and are restricted by the high frequency electric field. Deviation from the region where the DC electric field acts is suppressed. Therefore, even in an atmosphere with a relatively low degree of vacuum, ions can be sent out along the outgoing ion optical axis Co with high transport efficiency.

  In the above description, the incident ion optical axis Ci is set to be orthogonal to the ion incident surface Pi. However, the incident ion optical axis Ci is determined so that ions are incident on the ion incident surface Pi from an oblique direction. Also good. Since the DC electric field and the high-frequency electric field do not exert a force on the ions in the x-axis direction, when the ions are incident from an oblique direction, the ions are emitted from the ion emission surface Po in an oblique direction.

[Second Embodiment]
FIG. 5 is a schematic configuration diagram of an ion transport optical system 1B according to another embodiment (second embodiment) of the ion deflection apparatus according to the present invention, and FIG. 6 is a perspective view of an electrode portion of the ion transport optical system according to the second embodiment. It is. 5 and 6, the same components as those in the ion transport optical system in the first embodiment are denoted by the same reference numerals.

  In the ion transport optical system 1B according to the second embodiment, the remaining three rod electrodes 11, 12, 13 from which the fourth rod electrode 14 is removed in the first embodiment constitute an electrode portion. In this configuration, the ion incident surface Pi is on the surface including the first rod electrode 11 and the second rod electrode 12 as in the first embodiment, but the ion exit surface Po is the first rod electrode 11 and the third rod. It is set on the surface including the electrode 13. That is, the angle formed by the ion incident surface Pi and the ion emission surface Po is about 45 °.

The voltage applied to the three rod electrodes 11, 12, 13 is a voltage obtained by superimposing a high frequency voltage on a DC voltage as in the first embodiment. In this case, although there is no electrode corresponding to the fourth rod electrode 14 in the first embodiment, the space surrounded by the three rod electrodes 11, 12, 13 is generally the third rod in the y-axis-z-axis plane. A DC electric field that applies a force to ions is formed from the electrode 13 toward the first rod electrode 11, and a high-frequency electric field that applies a force so as to push ions into the space is formed. By appropriately adjusting the values of the DC voltages V _d1 , V _d2 , and V _d3 , ions incident along the incident ion optical axis Ci are deflected by about 45 ° and emitted along the outgoing ion optical axis Co. It is possible to make it. Further, the ions can be deflected at an angle other than 45 ° by appropriately adjusting the values of the DC voltages V _d1 , V _d2 , and V _d3 . Further, by changing the arrangement of the three rod electrodes 11, 12 and 13, ions can be deflected at an angle other than 45 °.

[Third embodiment]
FIG. 7 is a perspective view (a) and a top view (b) of an electrode portion of an ion transport optical system 1C according to another embodiment (third embodiment) of the ion deflection apparatus according to the present invention.

  In the configurations of the first and second embodiments, the high-frequency electric field has no action of binding ions in the extending direction (x-axis direction) of the rod electrodes 11, 12, 13, and 14. Therefore, a part of the ions may diverge in the direction (x-axis direction) orthogonal to the ion deflection surface (y-axis-z-axis plane), and the transport efficiency may be reduced. In order to avoid this, in the ion transport optical system 1C of the third embodiment, the rod electrode 15 extending in the y-axis direction at both edges in the x-axis direction of the space surrounded by the four rod electrodes 11-14. 16 are arranged as auxiliary electrodes. A DC voltage is applied to the two rod electrodes 15 and 16 so as to form a DC electric field that pushes ions back in the direction of the outgoing ion optical axis Co. For example, when the analysis target is positive ions, a positive DC voltage is applied to the rod electrodes 15 and 16, and when the analysis target is negative ions, a negative DC voltage is applied to the rod electrodes 15 and 16. This makes it difficult for ions to be dissipated during deflection and transport, thereby improving transport efficiency.

[Fourth embodiment]
FIG. 8 is a perspective view (a) and a top view (b) of an electrode portion of an ion transport optical system 1D according to another embodiment (fourth embodiment) of the ion deflection apparatus according to the present invention.

  In this embodiment, instead of the two rod electrodes 15 and 16 in the third embodiment, two plate electrodes 17 and 18 extending in parallel to the y-axis-z-axis plane are provided as auxiliary electrodes. As in the third embodiment, ions are pushed back in the direction of the outgoing ion optical axis Co by a DC electric field formed by applying a predetermined DC voltage to the flat plate electrodes 17 and 18, respectively, and the ion transport efficiency is increased. Can do.

[Fifth embodiment]
FIG. 9 is a perspective view of an electrode portion of an ion transport optical system 1E according to another embodiment (fifth embodiment) of the ion deflection apparatus according to the present invention. In this embodiment, as shown in the second embodiment, the rod electrodes 11, 12, and 13 are three, and then the two rod electrodes 15 and 16 that extend in the y-axis direction as in the third embodiment. Has been added. As a result, the transport efficiency can be improved after ions are deflected as in the second embodiment.

[Sixth embodiment]
FIG. 10 is a perspective view of an electrode portion of an ion transport optical system 1F according to another embodiment (sixth embodiment) of the ion deflection apparatus according to the present invention. In this embodiment, as shown in the second embodiment, three rod electrodes 11, 12, 13 are used, and then two sheets extending in parallel to the y-axis-z-axis plane as in the fourth embodiment. Flat plate electrodes 17 and 18 are added. As a result, the transport efficiency can be improved after ions are deflected as in the second embodiment.

  Each of the above embodiments is an example of the present invention, and it is obvious that modifications, changes, additions, and the like as appropriate within the scope of the present invention are included in the scope of the claims of the present application.

  For example, in the ion transport optical system in the above embodiment, three or four rod electrodes are used, but a configuration using five or more rod electrodes may be used. In that case, the ion incident surface Pi and the ion exit surface Po may not be provided on both sides of a certain one rod electrode. That is, the ion incident surface Pi and the ion emission surface Po can be respectively determined so as to include any two rod electrodes except for the same surface.

  In addition, the three or four rod electrodes need to be arranged substantially parallel to each other, but may not necessarily be arranged along three or four sides of the rectangular parallelepiped. In other words, in the first embodiment, the angle formed by the ion incident surface Pi and the ion exit surface Po may be not 90 °.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of an ICP mass spectrometer provided with the ion transport optical system by one Example (1st Example) of the ion deflection apparatus based on this invention. The schematic block diagram of the ion transport optical system by 1st Example. The top view of the electrode part of the ion transport optical system by 1st Example. The perspective view of the electrode part of the ion transport optical system by 1st Example. The schematic block diagram of the ion transport optical system by the other Example (2nd Example) of the ion deflection apparatus based on this invention. The perspective view of the electrode part of the ion transport optical system by 2nd Example. The perspective view (a) and top view (b) of the electrode part of the ion transport optical system by other Example (3rd Example) of the ion deflection | deviation apparatus based on this invention. The perspective view (a) and top view (b) of the electrode part of the ion transport optical system by other Example (4th Example) of the ion deflection | deviation apparatus based on this invention. The perspective view of the electrode part of the ion transport optical system by the other Example (5th Example) of the ion deflection | deviation apparatus based on this invention. The perspective view of the electrode part of the ion transport optical system by the other Example (6th Example) of the ion deflection apparatus based on this invention. 1 is a schematic block configuration diagram of a general mass spectrometer. 1 is a schematic configuration diagram of an off-axis ion transport optical system. FIG. The schematic block diagram which shows an example of the conventional axis-shifting ion transport optical system. The schematic block diagram which shows an example of the conventional axis-shifting ion transport optical system. The schematic block diagram which shows an example of the conventional axis-shifting ion transport optical system. The schematic block diagram which shows an example of the conventional axis-shifting ion transport optical system. The schematic block diagram which shows an example of the conventional axis-shifting ion transport optical system. The schematic block diagram which shows an example of the conventional axis-shifting ion transport optical system.

Explanation of symbols

1, 1B, 1C, 1D, 1E, 1F ... Ion transport optical system 2 ... Plasma torch 3 ... Sampling cone 4 ... Skimmer 5 ... First intermediate vacuum chamber 6 ... Second intermediate vacuum chamber 7 ... High vacuum chamber 8 ... Quadruple Polar mass filter 9 ... Ion detector 11, 12, 13, 14, 15, 16 ... Rod electrodes 17, 18 ... Flat plate electrodes 21, 22, 23, 24 ... Adders 31, 32, 33, 34 ... DC voltage source 40 ... high frequency voltage source 41 ... control unit Ci ... incident ion optical axis Co ... outgoing ion optical axis Pi ... ion incident surface Po ... ion outgoing surface

Claims (6)

An ion deflection apparatus that changes the traveling direction of ions by the action of an electric field,
a) A surface including two or more rod electrodes arranged in parallel to each other so as to surround a straight line, and including a surface including two rod electrodes adjacent to each other around the straight line is defined as an ion incident surface. An electrode portion including two rod electrodes adjacent to each other and having an ion exit surface different from the ion entrance surface;
b) A high-frequency electric field that applies a force to the ions so as to keep the ions incident on the space in the space surrounded by the plurality of rod electrodes of the electrode part, and across the ion incident surface in the space A DC voltage and a high frequency applied to each of the plurality of rod electrodes to form a DC electric field that applies a force to the ions to bend the trajectory of the ions so that the incident ions exit the ion exit surface. Voltage application means for applying a voltage superimposed with the voltage;
The ions incident on the space surrounded by the plurality of rod electrodes across the ion incident surface are constrained by the action of the high-frequency electric field, and the traveling direction is controlled by the action of the DC electric field. An ion deflection apparatus characterized in that it is bent and emitted from the ion emission surface .
  2. The ion deflecting device according to claim 1, wherein the electrode section is composed of three or four rod electrodes arranged on three or four sides of a rectangular parallelepiped.   The electrode unit further includes an auxiliary electrode disposed so as to sandwich a space surrounded by the plurality of rod electrodes from open end surfaces on both sides thereof, and the voltage applying unit includes an ion in the space on the auxiliary electrode. The ion deflecting device according to claim 1, wherein a direct current voltage that forms a direct current electric field for preventing the light from diverging in the extending direction of the straight line is applied.   The ion deflection apparatus according to claim 3, wherein the auxiliary electrode is a rod-shaped electrode extending in a direction orthogonal to the straight line.   The ion deflection apparatus according to claim 3, wherein the auxiliary electrode is a flat electrode extending in a direction orthogonal to the straight line. An ion source for ionizing a target component under an atmospheric pressure atmosphere, a mass analyzer for separating and detecting ions according to mass in a high vacuum atmosphere, and the ions generated in the ion source under the low vacuum atmosphere An ion transport unit for transporting to the mass analysis unit, wherein the ion deflection apparatus according to claim 1 is used as an off-axis ion transport optical system in the ion transport unit. apparatus.

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