JP2015038879A - Pseudo plane multireflection time-of-flight type mass spectrometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve convenience of manufacture by improving the sensitivity and resolution of a multireflection mass spectrometer.SOLUTION: A multireflection time-of-flight (MR-TOF) mass spectrometer comprises two pseudo plane electrostatic ion mirrors which extend in a drift direction (Z) and formed from parallel electrodes and separated by an electric field absent region. The MR-TOF comprises a pulsation ion source that emits an ion packet at a small angle in an X direction vertical to the drift direction Z. The ion packet is reflected between the ion mirrors and drifted in the drift direction. The mirrors are disposed in such a manner that the ion packet is converged within the time of flight on a receiver. The MR-TOF mirror provides spatial convergence in a Y direction vertical to both the drift direction Z and the ion implantation direction X. In a preferred embodiment, at least one mirror includes a feature part for cyclic spatial convergence of the ion packet in the drift direction Z.

Description

  The present invention relates generally to mass spectrometry, and more particularly to an apparatus including a multiple reflection time-of-flight mass spectrometer (MR-TOF MS) and methods of use thereof.

  Mass spectrometry is a well-known analytical chemistry tool used for the identification and quantitative analysis of various compounds and mixtures thereof. The sensitivity and resolution of such an analysis is important for practical use. It is well known that the time-of-flight mass spectrometer (TOF MS) resolution improves with increasing flight path. A multiple reflection time-of-flight mass spectrometer (MR-TOF MS) has been proposed to lengthen the flight path while maintaining a reasonable physical length. The use of MR-TOF MS became possible after the introduction of electrostatic ion mirrors with time-of-flight focusing characteristics. Patent Literature 1, Patent Literature 2, and Non-Patent Literature 1 disclose the use of an ion mirror to improve time-of-flight convergence with respect to ion energy. When an ion mirror is used, the ion flight path is automatically folded once.

H. Wollnik has made the possibility of an ion mirror to realize multiple reflection MR-TOF MS a reality. Patent Document 3 proposes shortening the overall length of the device by folding the ion path between a large number of gridless mirrors. Each mirror is made of coaxial electrodes. Two rows of such mirrors are aligned in the same plane or are arranged on two opposite parallel circles (see FIG. 1). By introducing a gridless ion mirror having a spatial ion focusing function, ion loss is reduced and the ion beam remains confined regardless of the number of reflections (see Patent Document 4 for more details). Further, the gridless mirror disclosed in Patent Document 3 provides “independence of ion flight time from ion energy”. The following two types of MR-TOF MS are disclosed.
(A) “Folded path” method. Equivalent to combining N sequentially reflecting TOF MSs. The flight path is folded along a zigzag orbit. (FIG. 1A)
(B) “Coaxial reflection” method. By using pulsed ion capture and release, multiple ion reflections between two axially aligned ion mirrors are used. (Fig. 1B)

  The “coaxial reflection” method is also described in Non-Patent Document 2, and has been implemented in the research published in Non-Patent Document 3. A resolution of 50,000 was achieved after 50 turns in a medium (30 cm) TOFMS. In practice, the gridless, spatially focused ion mirror retains ions of interest (loss was less than half), but the mass range shrinks in proportion to the number of cycles.

  MR-TOF mass spectrometers were also designed to use sector electric fields instead of ion mirrors (Non-Patent Documents 4 and 5). However, these mass spectrometers provide only primary energy convergence in time of flight, unlike those that utilize ion mirrors.

  Patent Document 5 introduces an advanced type return path MR-TOF MS using a two-dimensional gridless mirror. The MR-TOF MS has two identical mirrors made of rods that are parallel and symmetrical with respect to the intermediate plane between the mirrors and the plane of the folded ion path (see FIG. 2). . The mirror geometry and potential are determined to spatially focus the ion beam intersecting the plane of the folded ion path and provide secondary time-of-flight focusing for ion energy. The ions are multiply reflected between the plane mirrors and simultaneously slowly drift toward the detector in the so-called shift direction (X-axis in FIG. 2). The number of repetitions and the resolution are adjusted by changing the ion implantation angle. This scheme allows maintaining the entire mass range while extending the flight path.

  However, Nazarenko's planar mass spectrometer does not perform ion focusing in the shift direction, and thus the number of reflection cycles is substantially limited. Furthermore, the ion mirror used in the prototype does not provide time-of-flight convergence for the spatial ion spread that intersects the plane of the folded ion path, and therefore, by using divergent or broad beams, the time of flight is actually The resolution is reduced, and the flight path becomes meaningless.

In Patent Document 6, a planar multiple reflection mass spectrometer is
a) introducing ion mirrors that provide spatial focusing in the vertical higher order spatial and energy convergence while maintaining isochronism for higher order spatial and energy aberrations;
b) introducing a set of periodic lenses (lens systems) that hold the ion packet along the main zigzag ion path into the field-free region; and c) reversing the ion motion in the drift direction to Improvements have been made by introducing end deflectors that allow further extension.

  Further improvement of the planar multi-reflection TOF MS was made by an application by the present inventors (Patent Document 7, Patent Document 8, Patent Document 9 and Patent Document 10).

  These applications describe a number of pulsed ion sources, including various schemes for conversion of continuous ion beams into short ion packets and ion accumulation. U.S. Pat. No. 6,057,077 suggests a curved isochronous interface for ion implantation from an external pulsed ion source into the analyzer. This interface allows the fringing field of the analyzer to be avoided and this method improves the resolution of the instrument. The curved interface is compatible with trapped ion sources and pulsed converters based on orthogonal ion acceleration.

  Patent Document 8 suggests double orthogonal injection of ions into a so-called MR-TOF. Considering that the MR-TOF analyzer is more tolerant to the vertical spread (Y direction) of the ion packet, the continuous ion beam is relative to the zigzag ion trajectory plane in the MR-TOF. Oriented almost vertically. The accelerator is tilted slightly, the ion packet is turned after acceleration, and the change in tilt and orientation are corrected for each other.

  In Patent Document 9 and Patent Document 10, the MR-TOF analyzer is applied to various tandem TOF MSs. On the other hand, the equation uses a slow separation of the parent ions in the first MR-TOF and a fast analysis of the fragment ions in the second short TOF MS, for a number of parent ions in one shot of the pulsed ion source. A so-called parallel MS-MS analysis is performed.

  Since Patent Document 11 employs a “turn-back path” MR-TOF MS equipped with a planar gridless mirror having spatial and time-of-flight convergence characteristics, it is considered a prototype of the present invention.

  In implementing a planar multiple reflection mass spectrometer, the inventors have discovered that periodic lens systems generally interfere with the ion implantation interface and the pulsed ion source. The lens system also places significant limitations on the acceptance of the analyzer. The object of the present invention is to improve the sensitivity and resolution of multiple reflection mass spectrometers and to improve the convenience of their manufacture.

U.S. Pat. No. 4,072,862 Soviet Patent No. SU198034 British patent GB2080021 US Pat. No. 5,017,780 Soviet Patent No. 1725289 (1989) by Nazarenko et al. US Application No. 10 / 561,775 entitled “MULTI-REFLECTING TIME-OF-FLIGHT MASS SPECTROMETER AND METHOD OF USE” filed on December 20, 2005. WO2006102430 WO20077044696 WO2003US13262 WO2004008481 WO2004US19593

Sov. J. Tech. Phys. 41 (1971) 1498 by Mamyrin et al. Mass Spec. Rev., 1993, 12, p.109 by H.Wollnik et al. Int. J. Mass Spectrom. Ion Proc. 227 (2003) 217 Toyoda et al., J. Mass Spectrometry, 38 (2003), 1125 Satoh et al., J. Am. Soc. Mass Spectrom., 16 (2005), 1969

  The inventors have realized that the acceptance and resolution of MR-TOF MS having a substantially two-dimensional planar mirror can be further improved by periodically spatially modulating the electrostatic field of the ion mirror in the drift direction. Since the electric field of the ion mirror remains almost flat, a spectrometer with a small periodic modulation applied to the mirror electric field is called a pseudo-plane.

A preferred embodiment of the present invention is a multiple reflection time-of-flight mass spectrometer having one or more of the following features.
Two quasi-planar electrostatic ion mirrors extended in the drift direction (Z) and composed of parallel electrodes and separated by an electric field region;
A pulsed ion source that emits ion packets at a small angle with respect to the X direction perpendicular to the drift direction Z direction, so that the ion packets are reflected between the ion mirrors and drift in the drift direction;
A receiver for receiving ion packets,
The mirror is configured to provide time of flight convergence on the receiver;
The mirror is arranged to provide spatial focusing in the Y direction perpendicular to the drift direction Z direction and the ion implantation direction X direction, and at least one mirror periodically spatially focuses the ion packet in the Z direction; Therefore, it has a periodic feature that modulates the electrostatic field along the drift Z direction.

As described by the inventors in WO2004US19593, the ion mirror preferably has at least four electrodes, the at least one electrode providing time-of-flight convergence and said spatial Y-direction convergence Has an attracting potential. The device is optionally made as previously described in WO2004US19593,
-At least two lenses in the field-free region;
An end deflector to return the ion path to the drift direction;
Including features of a planar multiple reflection mass spectrometer, such as at least one isochronous curved interface between the pulsed ion source and the receiver.

The periodic modulation of the electrostatic field in the ion mirror in the Z direction is
-At least one auxiliary electrode having a periodic geometric structure in the Z direction is incorporated into at least one mirror electrode, and an adjustable potential is applied to this electrode or a set of electrodes to adjust the modulation intensity in the Z direction. ,
Creating a set of periodic slots in at least one of the mirror electrodes and adding an additional electrode with an electric field that enters those slots;
-Inserting at least one auxiliary electrode having a periodic geometric structure in the Z direction between the mirror electrodes;
The geometric shape of at least one mirror electrode is such that the height of the electrode opening (Y direction) changes periodically (Z direction) or the width of the electrode (X direction) changes periodically. correct,
• achieved by incorporating a set of periodic lenses in or between the internal electrodes of at least one ion mirror.
Many other field modulation methods are possible. A solution with adjustable Z-direction periodic modulation strength is preferred over a solution with fixed geometric modulation.

  The spectrometer preferably also includes the features previously described in the patent applications WO2004US19593, WO2006102430, WO20077044696, WO2003US13262 and WO2004008481, the disclosures of which are hereby incorporated as part of this specification. Incorporate.

The preferred time-of-flight analysis method of the present invention is:
Forming a packet of ions to be analyzed;
Passing ions between two parallel quasi-planar ion mirrors extended in the drift Z direction while maintaining a relatively small velocity component of the ion packet in the Z direction so that the ions move along a zigzag ion trajectory When,
Receiving ions at the receiver;
An electrostatic field is formed by the ion mirror so that ions are temporally converged and spatially converged in the Y direction, and this electric field is periodically spatially modulated in the Z direction within at least one mirror. The ion packet is spatially converged in the Z direction.

The method can be further carried out according to the steps described in WO2004US19593, i.e.
Spatially focusing the ion packet by at least two lenses in the drift space between the ion mirrors and returning the direction of ion drift at the edge of the analyzer;
Ion implantation through a curved isochronous interface.

Periodically modulating the electrostatic field in at least one ion mirror;
Spatially modulating the shape of at least one mirror electrode;
-Preferably, the intensity of the periodic convergence is adjustable, including any of the steps of introducing a periodic electric field by incorporating an auxiliary electrode.

  The period of the modulation is preferably equal to N * ΔZ / 2 or N * ΔZ, where N is an integer and ΔZ is the amount of advance of the ion trajectory in the drift direction per reflection at one mirror. It is.

  According to one embodiment of the present invention, the sensitivity and resolution of a multiple reflection mass spectrometer (MR MS) is improved.

  According to another embodiment of the invention, the production of MR MS is facilitated.

  These and other features, advantages and objects of the present invention will be better understood by those skilled in the art by reference to the following specification, claims and appended drawings.

It is a figure which shows prior art MR-TOF MS. It is a figure which shows prior art MR-TOF MS. 1 shows a prior art planar MR-TOF MS. FIG. 1 is a schematic diagram of a prior art planar MR-TOF MS with a periodic lens. FIG. FIG. 3 is a plan view of a preferred embodiment of a pseudo-planar ion mirror that achieves spatial electric field modulation with a mask electrode disposed between two mirror electrodes. FIG. 4B is a side view of the auxiliary electrode shown in FIG. 4A. FIG. 3 is a perspective view of a preferred embodiment of a quasi-planar ion mirror that achieves spatial electric field modulation with a mask electrode disposed between two mirror electrodes. FIG. 3 is a top view of a preferred embodiment of a pseudo-plane TOF MS that stably confines a narrow ion beam by returning ions in the Z direction by an end deflector. FIG. 4 is a top view of a preferred embodiment of a pseudo-plane TOF MS that returns ions in the Z direction by a deflection electric field constituted by a mask electrode divided into several parts having different potentials. In another preferred embodiment of a pseudo-plane TOF MS that uses a periodic mask electrode embedded in a single ion mirror to focus the ion flux in the Z direction, the initial parallel created by the orthogonal accelerator and extended in the Z direction. It is a top view which shows an ion beam. In a quasi-plane TOF MS that uses a periodic mask electrode embedded in a single ion mirror to focus the ion flux in the Z direction, a realistic angle and energy created by an orthogonal accelerator and expanded in the Z direction. It is a top view which shows transfer of the ion beam which has a breadth. FIG. 4 is a schematic view of an embodiment of the pseudo-planar MR-TOF MS of the present invention, where the lens is constituted by an additional electrode incorporated in the ion mirror electrode and has a period that is half the period of ion zigzag motion. FIG. 6 is a schematic diagram of an embodiment of the pseudo-planar MR-TOF MS of the present invention, where the lens is constituted by an additional electrode incorporated in the ion mirror electrode and has a period of one quarter of the period of ion zigzag motion. FIG. 6 is a schematic diagram of an embodiment in which a set of periodic lenses are added in the field-free region to further enhance ion focusing in the Z direction provided by additional electrodes disposed between mirror electrodes. FIG. 6 is a schematic diagram of an embodiment in which a set of periodic lenses is added in the field-free region to further enhance ion focusing in the Z direction provided by additional electrodes incorporated into the mirror electrode. FIG. 6 is a schematic diagram of an embodiment in which the modulated electrostatic field of the ion mirror is achieved by geometric modulation of at least one mirror electrode. It is the schematic which shows the modulation | alteration of an electric field by changing an electrode thickness periodically. It is the schematic which shows the modulation | alteration of an electric field by changing window height periodically. It is the schematic which shows the system which has the external ion source produced with the ion trap, and the external collision cell provided in the front | former stage of the 2nd TOF mass spectrometer.

  The present invention relates generally to the field of mass spectrometry, and more particularly to an apparatus including a multiple reflection time-of-flight mass spectrometer (MR TOF MS). Specifically, the present invention improves the resolution and sensitivity of planar and gridless MR-TOF MS by incorporating a slight periodic modulation of the mirror electrostatic field. The MR-TOF MS of the present invention has improved spatial and temporal convergence so that the acceptance of the ion beam along the extended folded ion path is widened and confinement is ensured. As a result, the MR-TOF MS of the present invention can be efficiently coupled to a continuous ion source via an ion storage device, thereby saving the duty cycle of ion sampling.

  FIGS. 1A and 1B show a prior art multiple reflection time-of-flight mass spectrometer (MR-TOF MS) according to Wollnik et al. British Patent 2080021 (British Patents FIGS. 3 and 4). In a time-of-flight mass spectrometer, ions of various masses and energies are emitted by the source 12. The flight path of ions to the collector 20 is folded back by multiple reflection of ions by mirrors R1, R2,... Rn. The mirror is such that the ion flight time is independent of ion energy. 1A and 1B show two geometrical arrangements of a plurality of axially symmetric ion mirrors. In both arrangements, the ion mirrors are placed in two parallel planes I and II and aligned along the plane of the ion path. In one arrangement, this surface is a plane (FIG. 1A), and in another arrangement, the surface is a cylinder 22 (FIG. 1B). Note that the ions move obliquely with respect to the optical axis of the ion mirror, which results in additional time-of-flight aberrations and thus the achievement of high resolution is quite complicated.

  FIG. 2 shows a “turnback path” MR-TOF MS of a prototype by Nazarenko et al. Described in Soviet Patent No. 1725289. MR-TOF MS has two gridless electrostatic mirrors, and each mirror is composed of three electrodes. That is, one mirror is composed of electrodes 3, 4 and 5, and the other mirror is composed of electrodes 6, 7 and 8. Each electrode consists of a pair of parallel electrodes “a” and “b” that are symmetrical about the “center” plane XZ. A source 1 and a receiver 2 are arranged in a drift space between the ion mirrors. The mirror provides multiple ion reflection. The number of reflections is adjusted by moving the ion source in the X-axis direction with respect to the detector. The patent describes a type of ion focusing that is achieved with all ion folds that achieves spatial ion focusing in the Y direction and secondary time-of-flight focusing with respect to ion energy.

Note that the structure of FIG. 2 does not provide ion focusing in the shift direction (ie, the Z-axis), thus substantially limiting the number of reflection cycles. This also does not provide time-of-flight convergence for spatial ion spread in the Y direction. Thus, the prototype MR-TOF MS cannot provide the wide acceptance of the analyzer and therefore cannot operate with an actual ion source.

  FIG. 3 is a schematic diagram of a planar MR-TOF MS with a prior art periodic lens by the inventors. The spectrometer has two parallel plane ion mirrors. Each mirror is composed of four electrodes 11 having a rectangular frame shape extending substantially in the drift Z direction. Far from the Z-direction edge of the mirror, the electric field is planar, ie it depends on X and Y and not on Z. The mirrors are separated by an electric field region 13. A set of periodic lenses 15 is disposed in the no-electric field region. An ion pulse is emitted from the ion source 1 at a small angle α with respect to the X axis. The ion packet is reflected between the mirrors while slowly drifting in the Z direction. The angle is selected so that the amount of advance in the Z direction per reflection coincides with the period of the periodic lens. The lens enhances ion motion along the zigzag trajectory. The end deflector 17 makes it possible to return the ion motion. The far end end deflector is set stationary. After passing through the deflector, the ions are directed along another zigzag trajectory toward the ion receiver 2, typically a time-of-flight detector (such as a microchannel plate (MCP) or secondary electron multiplier (SEM)). .

  FIG. 4 shows a preferred embodiment of the pseudo-planar MR-TOF MS of the present invention. In this embodiment, an auxiliary electrode having a periodic window 31 (also referred to herein as a mask window) disposed between two adjacent mirror electrodes 32 and 34 as shown in FIGS. 4A-4C. 30 constitutes a periodic electric field structure in the Z direction. The height in the Y direction of the mask window 31 is preferably equal to the opening in the Y direction of the mirror electrode. The interval in the Z direction of the mask window 31 is equal to the ion advance amount ΔZ per mirror reflection, and is equal to the opening in the Y direction of the ion mirror. The voltage applied to the mask electrode is slightly different from the intermediate potential between two adjacent mirror electrodes, and as a result, a weak periodic focusing electric field is generated in the Z direction. FIG. 4C shows an ion trajectory with a realistic angle (0.4 degrees) and energy spread (5%).

  In operation (FIG. 4D), a narrow ion bunch in the Z direction is formed by a pulsed ion converter, such as a linear ion trap source or a double orthogonal ejection device (WO 20077044696, the disclosure of which is hereby incorporated by reference). Incorporated herein as part of it). The latter forms an ion packet that is expanded in the Y direction but narrow in the Z direction. These ion fluxes are injected into the time-of-flight analyzer using a set of deflectors or a curved isochronous interface as disclosed in WO2006102430. The disclosure of WO2006102430 is incorporated herein as part of this specification. The packet is emitted at a small angle with respect to the axis X in the drawing plane, so that the ion advance amount ΔZ per reflection at the mirror coincides with the period of spatial modulation of the electric field in the ion mirror. Within the analyzer, ions move along a zigzag trajectory that is periodically reflected by an ion mirror 34 that provides time convergence as well as spatial convergence in the Y direction. When passing through the mask electrode 30, the ions are focused by a periodic electric field in the Z direction. The desired focal length in the X direction of the mask electrode lens is equal to the half cycle of the zigzag motion. The ions are preferably folded by a deflector as disclosed in WO2004US19593 after reaching the end of the analyzer. The disclosure of WO2004US19593 is hereby incorporated by reference as part of this specification. Alternatively, the drift direction of the ion packet is reversed by a deflector incorporated in an ion mirror as will be described later. After passing through the analyzer (reciprocating in the Z direction), the ions are ejected to a detector or another receiver using a set of deflectors or a curved isochronous interface.

  FIG. 5 shows an alternative method of reflecting ions in the Z direction after reaching the far end (Z direction) of the analyzer. The ion mirror structure of the embodiment of FIG. 5 is generally similar to the embodiment of FIGS. 4A-4C, with the following differences. The reflection is performed by a weak deflection electric field generated by the end mask window 40 divided into two parts 41 and 42, and different potentials are applied to the end parts of the window. Generally, when the mask is cut into a plurality of portions and a slightly different potential is applied to these portions, the drift angle can be gradually changed in the analyzer.

  6A and 6B show another option of the preferred embodiment where the analyzer allows ion packets that are long in the Z direction. Also in this case, ion focusing in the Z direction is performed by the auxiliary electrode 50 having the periodic window 51. However, in this case, the size of the mask window 51 is substantially larger than the window in the Y direction of the mirror electrode. An ion flux expanded in the Z direction is formed by the orthogonal accelerator positioned between the mirrors. After acceleration, the ion packet moves along a zigzag path. As shown in FIG. 6, the mask is preferably implemented in only one mirror, and the mask window step is preferably equal to the period 2ΔZ of ion motion in the Z direction. Alternatively, the mask is mounted on both mirrors as shown in FIG. 4, and the position of the mask window on the opposing mirror is shifted by ΔZ in the Z direction. The ions are received by detector 54 after passing through the analyzer. The mask voltage is preferably adjusted to provide an initial parallel monoenergetic ion beam after several reflections, eg, at half the flight path length as shown in FIG. 6A. Optimal adjustment of the potential can both reduce time-of-flight aberrations caused by the mask and ion confinement at realistic angles and energy spreads along all flight paths as shown in FIG. 6B.

  FIG. 7A shows an overview of another embodiment of the quasi-planar MR-TOF MS of the present invention, in which the periodic lens 60 is added to the adjacent ion mirror electrode (here, the internal electrode) in the field-free region. Consists of electrodes. The lens period in FIG. 7A is equivalent to the half period of the ion zigzag motion (one lens per reflection). Alternatively, as shown in FIG. 7B, the period of the lens 62 may be a quarter of the period of the ion zigzag motion (two lenses per reflection).

  FIG. 8 illustrates a no-electric field to further enhance ion focusing in the Z direction provided by an additional electrode disposed between mirror electrodes as in FIG. 8A or mounted in mirror electrode 72 as in FIG. 8B. Fig. 6 shows yet another embodiment in which a set of periodic lenses 70 are added in the region. A set of periodic lenses in the field-free space can be replaced by a set of beam limiting masks, which are not sufficiently converged by the periodic electric field of the quasi-planar mirror or excessively Ions that are focused and thus reach the detector after a different number of reflections are prevented from hitting the detector.

  FIG. 9A shows yet another embodiment in which modulation of the electrostatic field of the ion mirror is achieved by geometric modulation of at least one mirror electrode. FIG. 9B shows the modulation of the electric field by periodically changing the electrode thickness. FIG. 9C shows the modulation of the electric field by periodically changing the window height. Since the electrode potential is fixed to provide the best time-of-flight and space convergence, the geometric modulation causes a constant intensity Z-direction ion convergence determined by the selected geometric modulation. The modulation intensity must be selected so that the acceptance and resolution of the analyzer are compatible.

  FIG. 10 shows a configuration in which an external ion source created by the ion trap 80 and an external collision cell are provided, and the second TOF mass spectrometer 90 is provided after the external collision cell. The external device is coupled to the MRT via a curved isochronous interface 85. Such a configuration of the tandem TOF device is described in patent applications WO2003US13262 and WO2004008481.

  The figure shows several different configurations described in the prior application by the inventors. Single stage TOF MS uses an ion trap to accumulate ions coming from a continuous ion source. An ion packet is injected into the analyzer via the curved electric field interface 85. The ion passes through the analyzer twice and then passes through the second path of the isochronous interface and strikes the common TOF detector (not shown).

  When operating the instrument as a high-throughput tandem mass spectrometer, the detector is replaced by a fast collision cell in front of the fast second TOF spectrometer. While the parent ions are separated in the MR-TOF MS, fragments are rapidly formed and each ionic species is analyzed at once. This allows so-called parallel MS-MS analysis on multiple parent ions without introducing additional ion losses normally associated with scanning in other types of tandem instruments.

  When the instrument is operated as a high resolution tandem, ions are periodically injected from the axial trap into the MRT analyzer. A single ion species is time selected and returned to the axial trap. At this time, the axis trap acts as a fragmentation cell. The fragments collide and decay in the gas cell and are returned into the same MRT analyzer for fragment mass analysis.

  The above description is considered that of the preferred embodiment only. Those skilled in the art and those who make or use the present invention will devise variations of the present invention. Accordingly, the embodiments shown in the drawings and described above are merely illustrative and are not intended to limit the scope of the invention, which is to be interpreted in accordance with the principles of patent law, including equivalent theory. It should be understood that this is defined by the claims.

DESCRIPTION OF SYMBOLS 1 Ion source 2 Receiver 3-8 Electrostatic ion mirror 13 No electric field area

Claims (20)

A multiple reflection time-of-flight mass spectrometer,
Two quasi-planar electrostatic ion mirrors extending in the drift direction (Z) and composed of parallel electrodes and separated by a field-free region;
A pulsed ion source that emits the ion packet at a small angle with respect to the X direction perpendicular to the drift direction Z such that the ion packet is reflected between the ion mirrors and drifts in the drift direction Z;
A receiver for receiving ion packets,
The mirror is positioned to provide time of flight convergence on the receiver and to provide spatial convergence in the Y direction perpendicular to both the drift direction Z and the ion implantation direction X;
A multi-reflection time-of-flight mass spectrometer, wherein at least one mirror has a periodic feature that modulates the electrostatic field along the drift Z direction to periodically spatially focus ion packets in the Z direction.   The apparatus of claim 1, comprising at least one end deflector for returning the ion path in a direction opposite to the drift direction.   The apparatus of claim 1, further comprising at least one isochronous curved interface provided between the pulsed ion source and the receiver. The apparatus of claim 1, further comprising at least two lenses provided in the field-free region.   The at least one mirror has at least four electrodes, and an attractive potential is applied to the at least one electrode to provide the time-of-flight convergence and the spatial convergence in the Y direction. The device described in 1.   The apparatus of claim 1, wherein the periodic feature comprises at least one mirror electrode having an aperture that varies in height (Y direction).   The apparatus of claim 1, wherein the periodic feature comprises at least one mirror electrode that varies in width (X direction).   The apparatus of claim 1, wherein the periodic feature is a set of periodic lenses incorporated into an internal electrode of at least one ion mirror.   The apparatus of claim 1, wherein the periodic feature comprises a set of auxiliary electrodes incorporated in at least one mirror electrode, and the potential of the auxiliary electrodes periodically changes in the Z direction.   The periodic feature has a period equal to N * ΔZ / 2, where N is an integer and ΔZ is the amount of advance in the drift direction of the ion zigzag trajectory per reflection. The apparatus according to 1.   The apparatus of claim 1, wherein the periodic feature has a period equal to an integer number of periods of the zigzag trajectory. A time-of-flight analysis method,
Forming a packet of analyte ions;
Passing ions between two parallel quasi-planar ion mirrors extending in the drift Z direction while maintaining a relatively small velocity component in the Z direction of the ion packet so that the ions move along a zigzag ion trajectory When,
Receiving ions at the receiver;
Focusing the ions temporally and spatially in the Y direction;
Spatially and periodically modulating the electrostatic field in the at least one mirror to provide spatial focusing of the ion packets along the Z direction.   13. The method of claim 12, further comprising reversing the ion drift direction at the edge of the analyzer.   The method of claim 12, further comprising implanting ions through a curved isochronous interface.   The method of claim 12, further comprising spatially focusing the ion packet by at least two lenses in a drift space between the ion mirrors.   The method of claim 12, wherein the step of periodically modulating an electrostatic field within at least one ion mirror comprises spatially modulating the shape of at least one mirror electrode.   The method of claim 12, wherein the step of periodically modulating an electrostatic field in at least one ion mirror comprises introducing a periodic electric field of an auxiliary electrode.   The period of the modulation is equal to N * ΔZ / 2, where N is an integer and ΔZ is the amount of advance in the drift direction of the ion zigzag trajectory per reflection. Method.   The method of claim 12, wherein forming the ion packet comprises ion accumulation of ions coming from a continuous ion source. The method of claim 12, wherein the intensity of periodic convergence in the Z direction is adjustable.

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