Electron induced dissociation apparatus and method

Abstract

An electrode (150) for use in ion reaction devices such as electron-induced dissociation cells is disclosed to reduce contamination due to polymer buildup and increase the useful lifetime of such electrodes. To reduce contamination, the new electrode design includes an X-shaped aperture (160) in place of a conventional central circular aperture. The electrode is particularly useful in a system of multiple branch electrodes (152) having a first axis defining controlled passage of charged ions and a transverse axis for passage of an electron beam. The electrode is adapted to be disposed between an electron source and the branch electrodes to provide an aperture for passage of the electron beam while also preventing ions and reaction products from escaping the device. The X-shaped aperture eliminates or reduces the portion of the electrode surface that is most susceptible to contamination by polymer buildup.

Description

[0001] Related US applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 908,773, filed October 1, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The teachings of this article relate to induced ion reactions for mass spectrometry, and more specifically, to methods and systems for performing electron-induced dissociation (EID). Background Technology

[0004] Ionic reactions typically involve the reaction of a positively or negatively charged ion with another charged substance, which can be another positively or negatively charged ion or electron. For example, in electron-induced dissociation (EID), the charged substance is an electron beam, and electrons bombard the ions, causing them to fragment. EID has been used to dissociate biomolecules in mass spectrometry (MS) and has provided the capability to cover a wide range of potential applications, from routine proteomics in liquid chromatography-mass spectrometry / mass spectrometry (LC-MS / MS) to top-down analysis (without dissociation), de novo sequencing (discovery of anomalous amino acid sequences), post-translational modification studies (glycosylation, phosphorylation, etc.), protein-protein interactions (protein functional studies), and even small molecule identification.

[0005] Mechanisms for electron-induced dissociation (EID) can include, for example, electron capture dissociation (ECD) using electrons with kinetic energies of 0 to 3 eV, thermal ECD (electrons with kinetic energies of 5 to 10 eV), and high-energy electron ionization dissociation (HEEID) (electrons with kinetic energies greater than 13 eV). These electron-induced dissociations are considered complementary to conventional collision-induced or activated dissociation (CID or CAD) and have been incorporated into advanced MS devices.

[0006] The use of the term EID in the following text should be understood to encompass all forms of electron-related dissociation techniques and is not limited to electrons with kinetic energy at any particular level.

[0007] In conventional MS systems, electrons are introduced as a transverse beam, causing them to collide with precursor positive ions as the ions pass through the instrument axially. For example, a mass spectrometer may include a branched RF ion trap structure in which the electron beam is orthogonally injected into the analytical ion beam, wherein the ion beam and electron beam are independently controlled. See PCT application No. PCT / IB2014 / 00893, filed May 29, 2014, the entire contents of which are incorporated herein by reference for further details. Such a device can operate in either a flow-through mode or a simultaneous capture mode.

[0008] When a transverse electron beam is injected into an MS instrument, the beam must be controlled to confine and guide the electrons to regions where they can most effectively interact (i.e., dissociate) with ions passing through the instrument. Electron beam control is typically achieved by applying an electric field gradient, for example, by a series of positively biased electrodes that act as lenses to guide and focus the beam. The last of these electrodes is often called the “polar electrode” and is typically a positively biased metal plate with a central aperture through which the electron beam passes. The voltage of the polar electrode also acts as a confinement element, repelling positively charged precursor and product ions to retain them within the instrument so they can be extracted and analyzed.

[0009] It has been observed that the electrode may become less efficient in ion confinement over time. This functional degradation is believed to be a result of contamination caused by polymer deposits accumulating on the electrode surface. These deposits are understood to be caused by residual vacuum gas molecules, typically hydrocarbons from the coarse vacuum pump, which aggregate over time with stray electrons from the electron beam. Prolonged use results in a thicker, viscous polymer layer. The polymer has almost no electrical conductivity and allows for the accumulation of additional electrons on its surface, thus rendering any positive voltage applied to the electrode ineffective. This compromised potential gradually deteriorates the ion trapping performance.

[0010] A common method to reduce this polymerization is to coat the electrode surface with, for example... Graphite slurry has been used, but this is not a perfect solution because polymer buildup eventually occurs even on rough graphite surfaces. Changing the composition of the electrode itself or coating the electrode surface with other metals such as gold, stainless steel, or molybdenum has also not proven effective.

[0011] Therefore, there is a need for methods that can better reduce polymer buildup on electrodes than graphite coating, and for electrode designs that are less prone to contamination, thereby avoiding frequent instrument servicing and extending the lifespan of the electrodes. Summary of the Invention

[0012] According to this teaching, a novel electrode design is disclosed that reduces contamination due to polymer buildup and increases the lifespan of such electrodes. Polymer residues have been observed most noticeably on certain portions of the electrode, namely along the gap region between the underlying quadrupole electrodes in the case of a quadrupole RF structure. Without being bound by any theory or assumption, it appears that stray electrons leading to polymerization primarily affect the electrode surface in these gap regions due to the combined effects of the quadrupole RF electric field and / or parallel magnetic field. To reduce contamination, a novel electrode design is disclosed that includes an X-shaped opening instead of a conventional central circular aperture.

[0013] In one aspect of this teaching, an electrode for use in an ion reaction apparatus is disclosed, the apparatus having a plurality of branch electrodes defining a first axis for the controlled passage of charged ions and a transverse axis for the passage of an electron beam, and an electron source for introducing an electron beam along the transverse axis such that electron-induced dissociation of the ions passing through the electrons can occur in the cross region. The electrode of this teaching is adapted to be arranged between the electron source and the branch electrodes and provides an aperture for the passage of the electron beam while preventing the escape of ions and reaction products of electron-induced dissociation. The X-shaped aperture eliminates or reduces the portions of the electrode surface most susceptible to polymer buildup and contamination.

[0014] Specifically, the new electrode includes a conductive plate capable of being charged to a desired potential; and an X-shaped aperture. For example, the X-shaped aperture may be formed by at least two intersecting rectangular openings in the conductive plate, preferably equidistantly arranged between two adjacent electrodes of the transverse electrode. In some embodiments, the rectangular openings are completely cut-out openings in the conductive plate, while in other embodiments, the rectangular openings are partially cut-out recesses in the conductive plate.

[0015] The opening of the X-shaped aperture can have a width (narrower dimension) that is at least 1.5 times the diameter of the electron beam it is designed to be used with. In some embodiments, the rectangular opening of the X-shaped aperture can have a width greater than twice the diameter of the electron beam it is designed to be used with. For example, the rectangular opening of the X-shaped aperture can have a width greater than about 1 mm, or a width between about 1 and about 5 mm, or a width between about 2 and about 4 mm.

[0016] Furthermore, the rectangular opening of the X-shaped aperture has a length that is at least three times the diameter of the electron beam it is designed to be used with. In some embodiments, the length of the rectangular opening may be greater than four times the diameter of the electron beam it is designed to be used with. For example, the rectangular opening of the X-shaped aperture may have a length greater than about 3 mm, or a length between about 3 and about 8 mm, or a length between about 4 and about 6 mm.

[0017] In an alternative embodiment, the X-shaped aperture of the electrode can be star-shaped. In the star-shaped alternative, the center of the star is preferably formed as an aperture at least 1.5 times the width of the electron beam, preferably at least twice the width of the electron beam, and the point-to-point distance is at least 5 mm, preferably between 5 and 10 mm.

[0018] In another aspect of this teaching, a method for reducing contamination due to polymer buildup and extending the lifespan of electrode electrodes is disclosed, comprising providing a cross-shaped or star-shaped opening in the electrode electrode, the opening extending from a central region of the opening to a gap region between the electrode electrodes below.

[0019] The method of this teaching can be used to perform electron-induced dissociation by introducing a plurality of ions into a first pathway that extends at least partially along a first central axis and is defined by a first plurality of electrodes; and introducing electrons via an electron source into a second pathway that extends along a second central axis, the second pathway intersecting the first pathway at an intersection region, such that ions and electrons can interact. In the method of this teaching, an electrode is deployed between the electron source and the intersection region, the electrode providing an aperture for the passage of the electron beam while also preventing the escape of reaction products from ion- and electron-induced dissociation. The electrode includes a conductive plate capable of being biased to a desired potential and an X-shaped aperture. Any of the aforementioned electrodes can be used to practice the method of this teaching.

[0020] In another aspect of this teaching, a system for performing electron-induced dissociation is disclosed, which may include: a first set of electrodes, at least a first segment of which is arranged in a quadrupole orientation around a first central axis, wherein the first segment of the first set of electrodes extends axially along the first central axis from a proximal inlet end to a distal end to define a first portion of a first passage extending along the first central axis, wherein the proximal inlet end is configured to receive precursor ions from an ion source.

[0021] The system may also include a second set of electrodes, at least a first segment of which is arranged in a quadrupole orientation around a first central axis to define a second portion of the first passage, wherein the first segment of the second set of electrodes extends axially from a proximal end to a distal outlet end along the first central axis, and the proximal end of the second set of electrodes is spaced apart from the distal end of the first set of electrodes such that a lateral passage is formed between the proximal end of the second set of electrodes and the distal end of the first set of electrodes.

[0022] The lateral pathway (which will be used to introduce the electron beam) extends along the second central axis, which is substantially orthogonal to the first central axis and intersects the first pathway in the intersection region.

[0023] In this system, the electrodes of the first group of electrodes and the second group of electrodes are preferably branched (L-shaped) electrodes having longitudinal and transverse segments, wherein the longitudinal segment of each electrode of the first group of electrodes and the second group of electrodes respectively defines a first segment of the first group of electrodes and the second group of electrodes, and the transverse segment of each electrode of the first group of electrodes and the second group of electrodes further defines a transverse passage, wherein the transverse segments of two electrodes in the first group of electrodes and the transverse segments of two electrodes in the second group of electrodes are oriented to define a set of transverse electrodes arranged in a quadrupole orientation around a second central axis between the first axial end of the transverse passage and the intersection region.

[0024] The system may also include at least one electron source positioned near the transverse pathway for introducing a plurality of electrons along the second axis, such that the electrons can travel through the transverse pathway toward the intersection region. (It should be understood that, due to the symmetry of the system, the electron source can be positioned at either end of the transverse pathway, and in some embodiments, it may be advantageous to position two electron sources at opposite ends of the transverse pathway.)

[0025] Furthermore, the system may include at least one polar electrode disposed between an electron source and a lateral electrode, the polar electrode having an outer side facing the electron source and an inner side facing the lateral electrode. In some embodiments, the polar electrode may include a hole aligned with a second central axis to allow electrons to pass through, wherein the thickness of a portion of the polar electrode surrounding the hole on the outer side has been removed by an X-shaped cut, the X-shaped cut comprising two strip-shaped openings, for example, two generally rectangular openings intersecting at the hole and at 90 degrees to each other, oriented above the lateral electrode and in the gap region between the lateral electrodes. In this embodiment, each strip-shaped opening is positioned equidistantly between two adjacent electrodes of the lateral electrode.

[0026] Of course, in MS instruments employing higher-order multipole electrode designs, the notch will be modified accordingly. For a hexapole, an equivalent structure with three intersecting strip or star-shaped openings can be used; in an octapole design, four intersecting strip or star-shaped openings can be used, and so on. Any electrode described herein can be used in the systems taught in this application.

[0027] This article describes these and other characteristics of the applicant's teaching. Attached Figure Description

[0028] Those skilled in the art will understand that the accompanying drawings described below are for illustrative purposes only. The drawings are not intended to limit the scope of the applicant's teachings in any way.

[0029] Figure 1 A general schematic diagram of the ion reaction cell is depicted;

[0030] Figure 2 A cross-sectional view according to an embodiment of the present invention is depicted;

[0031] Figure 3A Depicting Figure 2 A cross-sectional view along line II;

[0032] Figure 3B Depicting Figure 2 A cross-sectional view along line II-II;

[0033] Figure 4 A simplified side view depicting an example of electron injection according to an embodiment of the present invention is shown;

[0034] Figure 5 A simplified side view depicting the focusing and defocusing effects of an electron beam according to an embodiment of the present invention is shown.

[0035] Figure 6 The invention depicts ion implantation and trapping into a device according to an embodiment of the invention;

[0036] Figure 7 The discharge of ions or ion reaction products from the device is depicted according to an embodiment of the present invention;

[0037] Figure 8 The continuous mode operation of an embodiment of the invention is described, wherein ions and electrons are continuously injected and a product ion stream, as a result of ion-electron interactions, is continuously discharged.

[0038] Figure 9 A cross-sectional view of an embodiment of the present invention is depicted, illustrating the direction of the magnetic field;

[0039] Figure 10 depicts a front view of a conventional electrode used with a lateral quadrupole RF electrode;

[0040] Figure 11 The electrode is depicted in accordance with this teaching and is used with a lateral quadrupole RF electrode;

[0041] Figure 12 An alternative electrode design based on this teaching is depicted for use with a lateral quadrupole RF electrode;

[0042] Figure 13 Another alternative electrode design based on this teaching is depicted for use with a lateral quadrupole RF electrode; and

[0043] Figure 14 The electrode is depicted in accordance with this teaching and is used with a transverse hexagonal RF electrode. Detailed Implementation

[0044] It will be understood that, for clarity, the following discussion will set forth various aspects of embodiments of the applicant's teachings, while omitting certain specific details where convenient or appropriate to do so. For example, the discussion of the same or similar features may be simplified in alternative embodiments. Well-known ideas or concepts may also not be discussed in detail for the sake of brevity. Those skilled in the art will recognize that some embodiments of the applicant's teachings may not require certain details specifically described in each implementation, which are set forth herein merely to provide a thorough understanding of the embodiments. Similarly, it will be apparent that the described embodiments may be readily altered or varied based on ordinary general knowledge without departing from the scope of this disclosure. The following detailed description of the embodiments is not to be construed as limiting the scope of the applicant's teachings in any way.

[0045] refer to Figure 1 The diagram depicts a general schematic of an embodiment of the invention. An ion reaction cell 1 receives as input a series of reactants, namely ions 2 and charged matter 3. Optionally, energy is added in the form of photons or light 4. Light 4 can be obtained from a laser source and is preferably light in the ultraviolet or infrared spectrum. Ions 2 can be any ion that is positively charged (cation) or negatively charged (anion). Charged matter 3 can be positively or negatively charged ions or electrons. As described in more detail below, in some preferred embodiments, the charged matter is an electron beam that is transversely transmitted to the ions 2 passing through the reaction cell 1 to initiate collisions and reactions. When the charged matter is electrons, the electron source can be a filament, such as a tungsten or thorium-plated tungsten filament, or other electron sources such as a Y₂O₃ cathode. The reaction apparatus may also include cooling gases, such as helium (He) and nitrogen (N₂). Typical pressures of the cooling gases can be 10... -2 Up to 10 -4 Between them.

[0046] Filament electron sources are typically used because they are inexpensive, but they are less robust in the presence of residual oxygen gases. Cathodes made of Y₂O₃, on the other hand, are more expensive electron sources but are more stable in oxygen, thus they can be used for de novo sequencing using free radical oxygen reactions. During operation, a current of 1 to 3 amperes is typically applied to heat the electron source, which generates 1 to 10 watts of thermal power. A cooling system for the electron source can be installed to keep the temperature of the magnets used (if present) below the Curie temperature at which their permanent magnets lose magnetization. Other known methods for cooling the magnets can also be used.

[0047] Within ion reactor 1, ions 2 and charged matter 3, along with optional photons 4, all interact. Depending on the nature of the reactants used, the interactions can cause a number of phenomena that lead to the formation of product ions 5, which can then be extracted or removed from ion reactor 1 along with other potentially unreacted ions 2 and / or possible charged matter 3, as appropriate.

[0048] When ion 2 is a cation and charged substance 3 is an electron, the cation can capture an electron and undergo electron capture dissociation, where the interaction between ion 2 and charged substance 3 leads to the formation of product ions 5, which are fragments of the initial ion 2. When ion 2 is a cation and charged substance 3 is an anion, the interaction between ion 2 and charged substance 3 can be electron transfer dissociation, where electrons are transferred from charged substance 3 to ion 2, causing ion 2 to fragment. The stream of material discharged from the ion reaction tank may include one or more or a mixture of ion 2 and / or its fragments.

[0049] Furthermore, for electron-related fragmentation, thermal ECD, high-energy electron ionization dissociation (HEEID), activated ion ECD (AI-ECD), electron collision excitation of ions from organic matter (EIEIO), electron separation dissociation (EDD), negative ETD, and negative ECD can be implemented. For example, when ion 2 is a cation, ECD, ETD, and thermal ECD can be implemented, while if ion 2 is an anion, EID can be used. Proton transfer reactions can also be implemented if the charged substance 3 is appropriately selected.

[0050] Now for reference Figure 2 The image depicts a side view of an ion reaction apparatus 10 according to an embodiment of the present invention. Shown as a cut-out section, the outer cylindrical housing 29 and the inner cylindrical housing 30 surround a first passageway 11 having a first central axis 12 and a first axial end 13 and a second axial end 14. This passageway provides a path for ions 2 to enter the ion reaction apparatus 10.

[0051] Gate electrodes (15, 16) are located at each end of the first passage 11. Gate electrode 15 allows ions 2 to enter the device 10 and gate electrode 16 controls the discharge of unreacted ions 2 or product ions 5 from the device 10. The gate electrodes do not need to be located directly at the axial end, but can be located only on the outside and close to the axial end. As will be understood, due to the symmetrical nature of the device, the direction of ions can be reversed if the surrounding ion transport devices are properly configured, wherein ions 2 enter through gate electrode 16 and exit through gate electrode 15.

[0052] Device 10 includes a first set of quadrupole electrodes 17 mounted to an inner cylindrical housing 30, the electrodes 17 arranged in a quadrupole configuration around a first central axis 12. While quadrupoles are specifically implemented here, any arrangement of multi-pole electrodes, including hexapoles, octaapoles, etc., can also be used. In the figure, only two of the four quadrupole electrodes are depicted, with the other two electrodes directly behind the depicted electrodes. Of the two depicted electrodes in the quadrupole electrodes 17, the electrodes have opposite polarities. These first set of quadrupole electrodes 17 are connected to an RF voltage source and a controller (not shown) for supplying an RF voltage to the electrodes to generate an RF field that can guide ions 2 toward the first central axis 12 (the midpoint of the quadrupole).

[0053] A second set of quadrupole electrodes 18 (only two are depicted, the other two are directly behind) is also mounted to the inner cylindrical housing 30 at a distance slightly from the first set of quadrupole electrodes 17, forming a generally cylindrical gap 19 between the first set of electrodes 17 and the second set of electrodes 18. The first quadrupole 17 and the second quadrupole 18 share the same central axis 12, and the rods of the first set of quadrupole 17 are aligned with the second set of quadrupole 18. Although depicted as cylindrical, it should be understood that the shape of this gap is not important; what is important is that there is a gap between the first set of quadrupole 17 and the second set of quadrupole 18. For example, this shape could also be depicted as a rectangular box shape even though the quadrupoles have the same configuration. This second set of quadrupole electrodes 18 is also attached to an RF voltage source and controller (not shown), which is used to provide an RF voltage to the electrodes to generate an RF field, which can be used to guide ions 2 and / or product ions 5 toward the central axis 12 (the midpoint of the second set of quadrupole electrodes 18).

[0054] The inner and outer cylindrical housings have cutouts for inserting a second passage 20, which has a second central axis 21 with a first axial end 22 and a second axial end 23. The second passage 20 provides a path for conveying charged material 3 into the device 10. The first and second passages are substantially orthogonal to each other and intersect at a point 24 along the first central axis 12 and the second central axis 21. Figure 2 The cross-sectional views taken by lines II and II-II Figure 3A and Figure 3B As can be more easily depicted, each of the four electrodes in the first set of quadrupole electrodes 17 can be paired with one of the four electrodes in the second set of electrodes 18, such that, for example, each electrode (25a, 25b) in each electrode pair has opposite polarity to the other electrode (25b, 25a) in the electrode pair and is directly opposite each other about the crossover point. A similar relationship exists for electrode pairs with electrodes (26a, 26b).

[0055] The same relationship applies to the two remaining electrodes in the first set of electrodes 17 that are paired with the two remaining electrodes in the second set of electrodes 18. This electrode orientation results in the RF field generated between the intersection 24 and the first axial end 22 of the second passage 20 being out of phase with the RF field generated between the intersection 24 and the second axial end 23 of the second passage 20. Because of this electrode configuration, there is essentially no RF field on the central axis 21.

[0056] The first axial end 22 of the second path 20 includes or has an electronic filament 27 nearby for generating electrons to be transported toward the intersection 24 into the second path 20. The first axial end 22 may also include or have one or more suitable electrode gates 28 nearby to control the entry of electrons into the device 10. A magnetic field source (not shown), such as a permanent magnet, is configured to achieve a magnetic field parallel to the second path 20. This magnetic field is useful when implementing ECD, thermal ECD, HEEID, EDD, and negative ECD in cases where the charged substance is electron. When the charged substance is a reactant anion and includes scenarios where, for example, the reaction occurring is an EDD reaction, a magnetic field source and magnetic field are not required.

[0057] The presence of a gap can cause ions to leak through the weaker side of the quadrupole RF field in the gap region of the cell. This can be mitigated by using a "pole" electrode, typically a plate-shaped electrode, positioned to prevent such leakage. The pole electrode is vertically aligned and spaced apart from the other electrodes. The positive charge on the pole electrode serves to repel charged ions and reaction products from the opening. As will be understood, this blocking electrode is electrically connected to a suitable voltage source.

[0058] Based on this teaching, an improved electrode design is disclosed. Figure 10 illustrates a conventional prior art electrode 150 configured to be deployed between an electron source (not shown) and a branched quadrupole electrode 152 (shown in dashed lines), defining a lateral pathway for introducing electrons into a reaction cell. The electrode 150 is generally a conductive plate capable of being charged to a desired potential. This conventional design includes a circular central aperture 154 for the passage of the electron beam.

[0059] Figure 11 An embodiment of the electrode 150A according to the present teachings is illustrated, wherein an X-shaped hole 160 replaces the circular hole of the prior art (Figure 10). Figure 11The X-shaped aperture is formed by two intersecting rectangular cutouts that intersect at the transverse axis. The rectangular cutouts are located between the lower quadrupole electrodes 152, and the narrower dimension of each rectangle is preferably wider than the electron beam, for example, greater than 1.5 times the width of the electron beam or at least twice the width of the electron beam. The length (longer dimension) of each rectangular cutout is preferably at least three times the width of the electron beam, more preferably at least four times the width of the electron beam. In some exemplary embodiments, the width (narrower dimension) of each rectangular cutout may be greater than 1.5 mm, or at least 2 mm. In some embodiments, the length may be greater than 3 mm, or greater than 4 mm.

[0060] Figure 12 An alternative electrode 150B according to this teaching is depicted for use with a lateral quadrupole RF electrode, wherein the conventional circular aperture (as shown in Figure 10) has been replaced by a star-shaped aperture 162 located between the lower quadrupole electrodes. At its center, the star-shaped aperture 162 is preferably wider than the electron beam, for example, greater than 1.5 times the width of the electron beam or at least twice the width of the beam. The length (longer dimension) of each star (point-to-point) is preferably at least three times the width of the electron beam, more preferably at least four times the width of the beam.

[0061] Figure 13 Another alternative electrode 150C according to this teaching is depicted for use with a lateral quadrupole RF electrode, wherein a central hole and an X-shaped partially cut-out opening (recess) replace the circular hole of the prior art (Fig. 10). Similar to... Figure 11 The manner of the embodiments, Figure 13 The X-shaped, partially cut-out hole is formed by two rectangular recesses intersecting at the transverse axis. These rectangular recesses are also located between the lower quadrupole electrodes 152, and the narrower dimension of each rectangle is preferably wider than the electron beam, for example, greater than 1.5 times the width of the electron beam or at least twice the width of the beam. The length (longer dimension) of each rectangular cut is preferably at least three times the width of the electron beam, more preferably at least four times the width of the beam. In some exemplary embodiments, the width (narrower dimension) of each rectangular cut may be greater than 1.5 mm, or at least 2 mm. The length may be greater than 3 mm, or greater than 4 mm.

[0062] Figure 14 An electrode 150D for use with a hexa-electrode RF electrode 166 in accordance with this teaching is depicted. Figure 14The X-shaped aperture is formed by three rectangular cuts intersecting at the transverse axis. The rectangular cuts are located between the lower hexagonal electrodes 166, and the narrower dimension of each rectangle is preferably wider than the electron beam, for example, greater than 1.5 times the width of the electron beam or at least twice the width of the beam. The length (longer dimension) of each rectangular cut is preferably at least three times the width of the electron beam, more preferably at least four times the width of the beam. In some exemplary embodiments, the width (narrower dimension) of each rectangular cut may be greater than 1.5 mm, or at least 2 mm. The length may be greater than 3 mm, or greater than 4 mm.

[0063] It should be understood that, Figure 14 The design used for hexapole instruments can be further modified and applied to higher-order multipole instruments, such as octapole instruments, and this design can also be modified to employ star-shaped or partially cut-out orifices in higher-order multipole instruments, similar to... Figure 12 and Figure 13 The holes shown are for the quad configuration.

[0064] The term "X-shaped," used in this article to describe the holes in the electrode, is intended to encompass, for example,... Figures 11-14 The complete and / or partial cut-off cruciform or star-shaped openings, as well as variant structures shown, provide similar anti-fouling protection by inhibiting polymer buildup on the electrode.

[0065] The electrode of this teaching can be coated with an anti-fouling coating (such as graphite slurry, for example) on the remaining portion of the electrode surface. They can be used together.

[0066] Refer again Figure 2 In some embodiments, the RF frequency applied to the quaternion is in the range of approximately 400 kHz to 1.2 MHz, preferably approximately 800 kHz.

[0067] Now for reference Figure 4Another embodiment depicting a side view of an ion reaction apparatus 40 is shown, wherein only charged material 3, specifically electrons, is injected. The ion reaction apparatus 40 includes a first passage 41 having a first central axis 42, a first axial end 43, and a second axial end 44. Electrode gates (45, 46) are located at each end of the first passage 41, allowing controlled entry and exit of ions into and out of the ion reaction apparatus 40. The apparatus 41 includes a first set of quadrupole electrodes 47, generally L-shaped, arranged around the first central axis 42. Only two of the four quadrupole electrodes are depicted in the figure; the other two are located directly behind the depicted electrodes. The two depicted electrodes of the quadrupole electrodes 47 have opposite polarities. A second set of quadrupole electrodes 48 (only two are depicted, the other two are directly behind) are also generally L-shaped, located at a distance slightly from the first set of quadrupole electrodes 47, forming a solid, generally cylindrical gap 49 between the first set of electrodes 47 and the second set of electrodes 48.

[0068] In the two electrodes depicted in the quadrupole electrode 48, the electrodes have opposite polarities. The electrodes depicted at the top of each group in the first group of quadrupole electrodes 47 and the second group of quadrupole electrodes 48 are opposite in polarity to each other. As those skilled in the art will understand, the two electrodes not shown in each group of quadrupole electrodes will have polarities such as, for example... Figure 3A and Figure 3B The quad electrodes in the configuration shown have the same polarity.

[0069] The second passage 50 has a second central axis 51 having a first axial end 52 and a second axial end 53. The second passage provides a path for transferring charged material into the device 40. This orientation of the electrodes results in an RF field generated between the intersection of the first passage 41 and the second passage 50 and the first axial end 52 of the second passage 50 being out of phase with the RF field generated between the intersection of the first passage 41 and the second passage 50 and the second axial end 53 of the second passage 50. The first axial end 52 of the second passage 50 includes or has an electronic filament 57 located nearby for generating electrons 60 for transfer into the second passage 50. The first axial end 52 may also include or have suitable electrode gates 63 located nearby for guiding electrons along the second passage into the device.

[0070] Electrode 58 further controls the entry of electrons 60 into device 40 and also serves to prevent the escape of ions and reaction products. Another electrode 59 is present or located near the second axial end 53 of the second passage 50. A magnetic field generator (not shown) is positioned and oriented in such a way as to generate a magnetic field parallel to the second passage. The direction of the magnetic field can be from the first axial end 52 to the second axial end 53 or vice versa. This magnetic field is useful when implementing ECD, thermal ECD, HEEID, EIEIO, EDD, and negative ECD in cases where the charged material is electrons. Grid 61 can be positioned as a gate to switch electrons 60 near or close to the electron filament 57. The RF field causes electrons 60, which are focused upon entering device 40, to become defocused as they approach the intersection of the first passage 41 and the second passage 50. As electrons 60 pass through the intersection, the polarity reversal of the RF field causes them to become focused again. This produces a more uniform distribution of electrons perpendicular to the first passage and increases the chance of ion-electron interactions in device 40, which can also lead to better sensitivity. The electron beam generates a localized attractive potential.

[0071] exist Figure 5 A clearer view of the electron defocusing effect is depicted, where device 70 is configured in a similar manner to device 40, having a first set of quadrupole electrodes 71 and a second set of quadrupole electrodes 72. In some embodiments, electron lenses with a potential of +1V are positioned at the entrance and exit of the electron beam path to aid in focusing the electron beam. For brevity, other parts are not repeated. The flow of electrons 60 entering device 70 is seen to defocus as they approach the center point 74, but refocus as they pass the center point. A magnetic field of 0.1T (not shown) is arranged parallel to and along the electron direction. This magnetic field is also useful when implementing ECD, thermal ECD, HEEID, EIEIO, EDD, and negative ECD when the charged matter is electrons. The RF field can be 100V peak-to-peak, and the electron beam energy at the center can be 0.2eV.

[0072] Figure 6 and Figure 7A side view depicting an ion trap effect generated in a batch manner by a device 100 according to an embodiment of the invention is shown. A first passage 101, including a first axial end 103 and a second axial end 104, provides a flow path for ions injected from the first axial end 103. A second passage 110, also including a first axial end 112 and a second axial end 113, provides a path for an electron beam generated by a filament 114. A set of quadrupole electrodes 107 (only two are depicted, the other two are directly behind) attached to a suitable RF voltage source assembly is oriented and used to guide ions to the midpoint to the central axis 102 within the quadrupole electrodes 107. A second set of quadrupole electrodes 108 (only two are depicted, the other two are directly behind) is located at a slightly greater distance from the first set of quadrupole electrodes 107, the distance between the first set of quadrupole electrodes 107 and the second set of quadrupole electrodes 108 forming a gap 109 between the electrode sets. This second set of quadrupole electrodes 108 is used to guide ions to the midpoint to the central axis 102 between the quadrupole electrodes 108. In the two electrodes depicted in quadrupole electrode 107, the electrodes have opposite polarities. In the two electrodes depicted in quadrupole electrode 108, the electrodes have opposite polarities. The top electrodes depicted in each of the first group of quadrupole electrodes 107 and the second group of quadrupole electrodes 108 are opposite in polarity to each other. As those skilled in the art will understand, the two electrodes not shown in each group of quadrupole electrodes will have polarities such as, for example... Figure 3A and Figure 3B The quadrupole electrodes in the configuration shown have consistent polarity. A magnetic field generator (not shown) generates a magnetic field oriented parallel to the second passage and aligned with the second central axis 111. This magnetic field is also useful when implementing ECD, thermal ECD, EIEIO, HEEID, EDD, and negative ECD in cases where the charged material is electrons. The inlet gate electrode 105 and the outlet lens gate electrode 106 control the ion inflow and outflow from the device 100, respectively. In this embodiment, the inlet lens gate electrode 105 is positioned at a potential that allows ion inflow into the device 100, while the outlet lens gate electrode 106 has a sufficiently high potential to temporarily prevent ions from flowing out of the device.

[0073] The second passage also includes or has nearby electrode 115, 116, which is positively biased to prevent ions from flowing out through the axial ends 112, 113 of the second passage 110. In this embodiment, the filament 114 begins to shut off when ions are implanted, and no charged material enters the device 100 via the second passage 110. In this way, the device 100 functions as an ion trap, where implanted ions accumulate at the intersection between the first passage 101 and the second passage 110.

[0074] When sufficient ions have accumulated, the potential of gate electrode 105 is increased to prevent ion inflow into device 100, thereby preventing ion entry and exit. Filament 114 can then be switched on, allowing electrons to enter device 100 through the holes in electrode 115. Once this is done, electrons can interact with ions and undergo EID, resulting in fragmentation into product ions. Once sufficient fragmentation has occurred, filament 114 can be switched off, the potential of gate electrode 105 can be increased, and the potential of gate electrode 106 can be decreased to allow product ions to exit through the second axial end 104, as... Figure 7 As depicted. Cooling gases, such as helium or nitrogen, can be introduced into device 100 to achieve more efficient trapping. Each electrode of the first quadrupole 107 and the second quadrupole 108 has a first portion oriented substantially parallel to the first central axis 102 and a second portion oriented substantially parallel to the second central axis. Since each portion of each electrode has the same polarity for a given electrode, these electrodes can collectively serve as a trap to guide ions to both central axis 102 and central axis 111. In this way, device 100 acts as a two-dimensional trap, or more precisely, a linear trap in two directions. Although in Figure 6 It is depicted as having a smooth, circular transition between the first and second parts, but other configurations such as sharp corners can also be used. Figure 6 and Figure 7 Each figure shown below the device is a spatial potential diagram of positive ions along the central axis 102 in the horizontal direction within the device.

[0075] exist Figure 6 In this configuration, the potential at the inlet is approximately equal to the potential of the isolated ion entering the device, thus allowing the ion to pass through and enter the device. The potential at the outlet is higher than the potential of the isolated ion entering the device, thus preventing the ion from exiting through the right side of the device and instead trapping it. Figure 7 In the process, the inlet potential is higher, thus preventing ions from retreating through the inlet, while the outlet potential is lower than that of the product ions, thus allowing ions to leave the device.

[0076] Figure 8A side view depicting the operation of device 100 in semi-continuous mode is shown, wherein ions continuously enter through gate 105 and electrons 117 continuously enter through holes in electrode 115. The interaction between ions and electrons 117 can induce EID, leading to fragmentation and the formation of product ions. These product ions, along with unreacted ions, are extracted from the device in a semi-continuous manner through gate electrode 106, which switches between open and closed positions. When in the closed position, the potential in the gate electrode is higher than the potential of the ions contained in the device, resulting in ion accumulation and allowing for increased residence and reaction times, enabling the EID reaction to occur. When ions are extracted, gate electrode 106 is opened by lowering the potential in the gate, thereby allowing the removal of product ions. Figure 8 The horizontal spatial representation of the positive ion potential shown below the device 100 shows the exit potential oscillating between high and low potentials representing the closed and open positions of the gate 106.

[0077] Now for reference Figure 9 The side view depicts another system 200 according to this teaching, which is inserted in series between two quadrupole filters. A quadrupole filter Q1 with a quadrupole 218 is located upstream of device 200 and is used for ion capture / guidance / etc., and provides an ion source at the inlet of device 200. A quadrupole Q2 with a quadrupole 219 is located downstream of device 200 and can be used to receive product ions and unreacted ions and, in the quadrupole, capture / guidance / etc., these substances for further analysis or processing. This device is similar to the previously described device and will not be described in detail for the sake of brevity. Device 200 has a first passage 201 and a second passage 210. Device 200 includes two filaments, each disposed at a first axial end 212 or a second axial end 213 of the second passage 210. This configuration allows for independent operation of the filaments, such that if one filament is in use and suddenly becomes inoperable, the other filament can be used as a backup and activated, resulting in no downtime or minimal downtime.

[0078] While the use of an additional quadrupole has been specifically exemplified, it will be understood that other types of devices may also be located before or after the device according to this teaching. For example, the device may include various ion guides, filters, traps, ion migration devices including differential migration and field asymmetric ion migration spectrometers, and other mass spectrometry devices such as time-of-flight mass spectrometers. In various embodiments, the electronically controlled optics and the ion-controlled optics are completely separate, thus allowing independent operation of the two charged particles. For electrons, the electron energy can be controlled by the electron source and the potential difference between the intersection of the ion pathway and the charged matter pathway. The charged matter pathway can be controlled in an on / off manner using gate electrodes. Lenses may be positioned at or near either axial end of the second pathway and, when positively biased, focus the charged matter (when such matter is electrons). Ions introduced through other pathways are stable near these lenses because these lenses are positively biased. It will also be understood that the design of the invention is also applicable to higher-order multipole structures, such as hexapole or octapole RF electrode structures.

[0079] For additional teachings on electron-induced dissociation, see U.S. Patent Application Publication No. 20180005810, filed December 21, 2015, entitled “Electron-Induced Dissociation Devices and Methods”; PCT Application No. PCT / IB2014 / 00893, filed May 29, 2014, entitled “Inline Ion Reaction Device Cell And Method of Operation”; and PCT Application No. PCT / IB2012 / 002621, filed December 6, 2012, entitled “Ion Extraction Method For IonTrap Mass Spectrometry”, each of which is incorporated herein by reference in its entirety.

[0080] It should be understood that many changes can be made to the disclosed embodiments without departing from the scope of this teaching. While the foregoing figures and examples involve specific elements, they are intended to be illustrative and not restrictive. Those skilled in the art will understand that various changes in form and detail can be made to the disclosed embodiments without departing from the scope of the teachings covered by the appended claims.

Claims

1. An electrode, comprising: A conductive plate configured to be electrically biased to a desired potential, wherein the electrode is adapted to be arranged between the RF electrode and the electron source of the ion reaction apparatus; and An X-shaped aperture is formed in the conductive plate through which an electron beam generated by the electron source enters a pathway in the ion reaction device to intersect with ions traveling through another pathway in the ion reaction device during operation. The X-shaped aperture eliminates or reduces contamination of a portion of the surface of the counter electrode.

2. The electrode according to claim 1, wherein the X-shaped hole is formed by at least two intersecting rectangular openings in the conductive plate, the rectangular openings being equidistantly arranged between two adjacent electrodes.

3. The electrode according to claim 2, wherein, The rectangular opening is a completely cut-out opening in the conductive plate.

4. The electrode according to claim 2, wherein, The rectangular opening is a partially cut-out recess in the conductive plate.

5. The electrode according to claim 2, wherein, The width of the rectangular opening of the X-shaped aperture is at least 1.5 times the diameter of the electron beam it is designed to be used with.

6. The electrode according to claim 2, wherein, The width of the rectangular opening of the X-shaped aperture is greater than twice the diameter of the electron beam it is designed to be used with.

7. The electrode according to claim 2, wherein, The rectangular opening of the X-shaped hole has a width greater than 1 mm.

8. The electrode according to claim 2, wherein, The rectangular opening of the X-shaped hole has a width between 1 mm and 5 mm.

9. The electrode according to claim 2, wherein, The rectangular opening of the X-shaped hole has a width between 2 mm and 4 mm.

10. The electrode according to claim 2, wherein, The length of the rectangular opening of the X-shaped aperture is at least three times the diameter of the electron beam it is designed to be used with.

11. The electrode according to claim 2, wherein, The length of the rectangular opening of the X-shaped aperture is greater than four times the diameter of the electron beam it is designed to be used with.

12. The electrode according to claim 2, wherein, The rectangular opening of the X-shaped hole has a length greater than 3 millimeters.

13. The electrode according to claim 2, wherein, The rectangular opening of the X-shaped hole has a width between 3 mm and 8 mm.

14. The electrode according to claim 2, wherein, The rectangular opening of the X-shaped hole has a width between 4 mm and 6 mm.

15. The electrode according to claim 2, wherein, The X-shaped hole is star-shaped.

16. A method for performing an ionic reaction, comprising: Multiple ions are introduced into a first pathway, which extends at least partially along a first central axis and is defined by a first plurality of electrodes; Electrons are introduced into a second pathway extending along the second central axis via an electron source. This second pathway intersects with the first pathway at the intersection region, allowing ions and electrons to interact. An electrode is disposed between the electron source and the cross region. The electrode provides an aperture for the electron beam to pass through while preventing the escape of reaction products from ion and electron-induced dissociation. The electrode includes a conductive plate configured to be electrically biased to a desired potential and an X-shaped aperture. The X-shaped hole eliminates or reduces contamination on a portion of the electrode surface.

17. The method of claim 16, wherein the step of providing an electrode with an X-shaped hole further comprises providing an electrode with an X-shaped hole formed by at least two intersecting rectangular openings in the conductive plate.

18. The method of claim 17, wherein the step of providing an electrode with an X-shaped hole further comprises providing an electrode with an X-shaped hole having a rectangular opening that is a completely cut-out opening in the conductive plate.

19. The method of claim 17, wherein the step of providing an electrode having an X-shaped hole further comprises providing an electrode having an X-shaped hole having a rectangular opening that is a partially cut-out recess in the conductive plate.

20. The method of claim 17, wherein, The width of the rectangular opening of the X-shaped aperture is at least 1.5 times the diameter of the electron beam it is designed to be used with.

21. The method according to claim 17, wherein, The width of the rectangular opening of the X-shaped aperture is greater than twice the diameter of the electron beam it is designed to be used with.

22. The method according to claim 17, wherein, The rectangular opening of the X-shaped hole has a width greater than 1 mm.

23. The method according to claim 17, wherein, The rectangular opening of the X-shaped hole has a width between 1 mm and 5 mm.

24. The method of claim 17, wherein, The rectangular opening of the X-shaped hole has a width between 2 mm and 4 mm.

25. The method according to claim 17, wherein, The length of the rectangular opening of the X-shaped aperture is at least three times the diameter of the electron beam it is designed to be used with.

26. The method according to claim 17, wherein, The length of the rectangular opening of the X-shaped aperture is greater than four times the diameter of the electron beam it is designed to be used with.

27. The method according to claim 17, wherein, The rectangular opening of the X-shaped hole has a length greater than 3 millimeters.

28. The method according to claim 17, wherein, The rectangular opening of the X-shaped hole has a width between 3 mm and 8 mm.

29. The method according to claim 17, wherein, The rectangular opening of the X-shaped hole has a width between 4 mm and 6 mm.

30. The method of claim 17, wherein, The X-shaped hole is star-shaped.

31. A system for performing electron-induced dissociation, comprising: A first set of electrodes, wherein at least a first segment of the first set of electrodes is arranged in a quadrupole orientation around a first central axis, wherein the first segment of the first set of electrodes extends axially from a proximal inlet end to a distal end along the first central axis to define a first portion of a first passage extending along the first central axis, the proximal inlet end being used to receive precursor ions from an ion source; A second set of electrodes, at least a first segment of which is arranged in a quadrupole orientation around a first central axis to define a second portion of a first passage, wherein the first segment of the second set of electrodes extends axially from a proximal end to a distal outlet end along the first central axis, the proximal end of the second set of electrodes being spaced apart from the distal end of the first set of electrodes, such that a lateral passage extends between the proximal end of the second set of electrodes and the distal end of the first set of electrodes, the lateral passage extending along a second central axis from a first axial end to a second axial end, the second central axis being substantially orthogonal to the first central axis, and the lateral passage intersecting the first passage in an intersection region; The electrodes of the first group of electrodes and the second group of electrodes are L-shaped electrodes having longitudinal and transverse segments, and the longitudinal segment of each electrode of the first group of electrodes and the second group of electrodes respectively defines a first segment of the first group of electrodes and the second group of electrodes, and the transverse segment of each electrode of the first group of electrodes and the second group of electrodes defines the transverse passage. The transverse segments of two electrodes in the first group of electrodes and the transverse segments of two electrodes in the second group of electrodes are oriented to define a set of transverse electrodes arranged in a quadrupole orientation around a second central axis between the first axial end of the transverse passage and the intersection region. An electron source is provided near the first axial end of the transverse passage and is used to introduce multiple electrons along the second central axis, so that the electrons travel toward the intersection region through the transverse passage in the first transverse direction. A polar electrode is disposed between an electron source and a lateral electrode, the polar electrode having an outer side facing the electron source and an inner side facing the lateral electrode, the polar electrode including a hole aligned with a second central axis to allow electrons to pass through therethrough, wherein a portion of the thickness of the polar electrode surrounding the hole on the outer side has been removed to form an X-shaped hole. The X-shaped hole eliminates or reduces contamination on a portion of the electrode surface.

32. The system of claim 31, wherein the X-shaped aperture comprises at least two intersecting rectangular openings at 90 degrees to each other, the rectangular openings being equidistantly arranged between two adjacent electrodes of the transverse electrode.

33. The system according to claim 32, wherein, The rectangular opening is a completely cut-out opening in the conductive plate.

34. The system according to claim 32, wherein, The rectangular opening is a partially cut-out recess in the conductive plate.

35. The system according to claim 32, wherein, The width of the rectangular opening of the X-shaped aperture is at least 1.5 times the diameter of the electron beam it is designed to be used with.

36. The system according to claim 32, wherein, The width of the rectangular opening of the X-shaped aperture is greater than twice the diameter of the electron beam it is designed to be used with.

37. The system according to claim 32, wherein, The rectangular opening of the X-shaped hole has a width greater than 1 mm.

38. The system according to claim 32, wherein, The rectangular opening of the X-shaped hole has a width between 1 mm and 5 mm.

39. The system according to claim 32, wherein, The rectangular opening of the X-shaped hole has a width between 2 mm and 4 mm.

40. The system according to claim 32, wherein, The length of the rectangular opening of the X-shaped aperture is at least three times the diameter of the electron beam it is designed to be used with.

41. The system according to claim 32, wherein, The length of the rectangular opening of the X-shaped aperture is greater than four times the diameter of the electron beam it is designed to be used with.

42. The system according to claim 32, wherein, The rectangular opening of the X-shaped hole has a length greater than 3 millimeters.

43. The system according to claim 32, wherein, The rectangular opening of the X-shaped hole has a width between 3 mm and 8 mm.

44. The system according to claim 32, wherein, The rectangular opening of the X-shaped hole has a width between 4 mm and 6 mm.

45. The system according to claim 32, wherein, The X-shaped hole is star-shaped.

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