Ion guide including DC electrode

Abstract

An ion guide is provided that includes an inlet for allowing ions to enter the ion guide, where the ions allowed to enter are guided along a first axis. The ion guide also includes a confinement device including an array of radio frequency (RF) electrodes formed along the first surface and configured to provide an RF field for confinement of ions allowed to enter. The ion guide also includes a first direct current (DC) electrode configured to receive the DC potential and thereby provide a force on the ions allowed to enter, the force having a component on a second axis perpendicular to the first axis. The first DC electrode has a surface inclined with respect to the first axis and the second axis.

Description

Technical Field

[0001] The present disclosure relates to an ion guide. Specifically, the present disclosure provides ion guides that achieve complex ion motion by using DC electrodes to alter the path of ions through the ion guide. Background Art

[0002] Ion guides have traditionally been linear devices that transport ions from an inlet along a defined channel to an outlet. Ion guides are also capable of trapping ions for a duration. The most common ion guides are multipole ion guides, although the channel can also be defined by an RF surface generated from a series of stacked ring electrodes to which an alternating current RF is applied.

[0003] For more complex ion manipulation, such as switching ion motion between several possible pathways or generating extended folded pathways suitable for high-resolution ion mobility analysis, a more complex design is required.

[0004] A two-dimensional plane can be formed by a stack of elongated electrodes that generate a flat RF surface that repels ions. Two such RF surfaces or a single surface with opposing electrodes can form an RF blanket (G. Bollen, Int. J. Mass Spectrom., 2011, 299, 131 - 138). US6894286B2 and US6794641B2 relate to the manipulation of trapped ions within such structures by DC gradients, DC barriers, and traveling waves. Another example of this concept is the Lossless Ion Manipulation Structure (SLIM) ion guide US8835839B1, US9812311B2, US11209393B2. In such examples, an RF pseudopotential surface is generated on a PCB printed electrode, while printed support DC and T-wave electrodes around the RF electrode handle the transport of ions.

[0005] There are examples of known beam switching devices, such as devices with switchable ion paths. The SLIM device is described in US20190103261A1, where such a device can be used as a beam switching device, thereby generating a potential to inhibit the motion of ions in a first direction. Other examples of beam switching devices exist in US7829850B2, US9984861B2, and US8581181B2.

[0006] In ion mobility analysis where ions drift along a channel at different speeds depending on their mobility, a longer flight path results in higher resolution. It has been demonstrated that only SLIM ion guides and multi-pass circular ion guides produce flight paths greater than 10 meters.

[0007] Therefore, there is a desire to provide a simple ion guide that achieves complex ion motion. Summary of the invention

[0008] According to a first aspect, there is provided an ion guide, the ion guide comprising:

[0009] An inlet for allowing ions to enter the ion guide, wherein the ions are allowed to enter the ion guide.

[0010] Incoming ions are directed along a first axis;

[0011] A restraint device comprising a radio frequency (RF) electrode array, the radio frequency (RF)

[0012] An electrode array is formed along the first surface and is configured to provide an RF field for confining the admitted ions; and

[0013] A first direct current (DC) electrode is configured to receive a DC

[0014] The potential thereby provides a force on the admitted ions, the force having a component in a second axis perpendicular to the first axis, the first DC electrode having a surface inclined relative to the first axis and the second axis.

[0015] The inventors have understood that an ion guide having a DC electrode configured to receive a DC potential has the advantage that ions initially guided along a first axis can then be pushed along a second axis by the force provided by the DC electrode. It has been understood that by providing an ion guide having a DC electrode with a surface inclined relative to the first axis and the second axis, ions are pushed along the inclined surface because the force generated has a component on the second axis. Therefore, the ion path can be changed by the DC electrode, which provides a more complex ion path without requiring a complex system. By providing an ion guide for a complex ion path, the ion guide can be used for a folded ion path, a switchable or branching path, or can be used for compressing, expanding and / or splitting an ion beam. The ion guide therefore produces a complex ion path while being mechanically and electronically simple. Constructing the DC electrodes within the electrode array is relatively low-cost and simple, as will be described herein.

[0016] The ions may be allowed to enter the ion guide along the first axis. Alternatively, the ions may be allowed to enter the ion guide in a direction different from the first axis. Thus, the inlet may be at any location within the ion guide and the same technical result will be achieved, i.e., the ions will be directed towards the inclined surface of the DC electrode.

[0017] Ions can be guided along a first axis by applying a DC gradient or a DC traveling wave to an electrode array or by a gas force. Alternatively or additionally, the ion guide may further include an additional DC electrode. For example, the additional DC electrode may be mounted between the RF electrodes on the first surface, and a DC gradient or a DC traveling wave may be applied to the additional DC electrode to guide ions along the first axis. Alternatively or additionally, an additional DC electrode may be provided in a counter electrode, which will be described herein. This has the advantage of guiding (i.e., pushing) ions in a direction after allowing them to enter the ion guide, where the direction of guiding the ions can be independent of the direction in which the ions are allowed to enter. The direction of ion travel can be altered by a DC gradient, a DC traveling wave, or a gas force, i.e., the ions are guided by a first force. Thus, the ions can be pushed in a direction towards the first DC electrode, which may or may not be in the direction in which the ions were initially allowed to enter the ion guide.

[0018] The inlet can be configured to allow ions to enter the ion guide along a first axis. Alternatively, the inlet can be configured to allow ions to enter the ion guide in a direction different from the first axis (e.g., along a second axis).

[0019] The RF electrode array can form an RF surface.

[0020] The ion guide may further include an exit through which ions are extracted. The inlet and the exit may be offset from each other on a second axis (i.e., the z-axis), where the second axis is perpendicular to the first axis (i.e., the x-axis). The inlet and the exit may be in the same plane, where the plane is substantially parallel to the first surface. The ions may travel substantially in the plane in which the inlet (i.e., the entrance) and the exit (i.e., the withdrawal exit) are located. Thus, the ions may move from the inlet to the exit by moving in substantially the same plane, rather than requiring a change in plane, i.e., moving closer to or further away from the RF surface. After allowing ions to enter the inlet, one or more DC electrodes may move the ions in the z-direction (along the z-axis) when the ions are moving in the x-direction (the direction along the x-axis) between the side of the ion guide including the inlet and the side of the ion guide including the exit. In some embodiments, the ions may be separated from neutral contaminants by moving the ions in different directions in substantially the same plane. The ions move in the z-direction as well as the x-direction such that the ions travel from the inlet to the exit. However, the neutral contaminants travel only in the x-direction due to their lack of charge and thus do not leave the ion guide via the exit because the inlet is offset from the exit. The first DC electrode may be located on one side of the exit, and the second DC electrode may be provided on the other side of the exit such that the exit is within the gap between the first DC electrode and the second DC electrode. The first DC electrode and the second DC electrode may each have a surface (referred to herein as an inclined surface) that is inclined with respect to the first axis and the second axis and that is configured to push the ions towards the exit in opposite z-directions such that the ion beam is compressed in the z-direction when the ions are extracted through the exit (i.e., withdrawn from the ion guide via the exit). The inlet may have a greater width in the z-direction than the exit. The ion guide may be arranged between an ion source configured to supply ions to the entrance and a vacuum chamber for receiving ions from the withdrawal exit.

[0021] The first DC electrode may have a length along the second axis, a width along the first axis, and a depth along a third axis (the third axis being perpendicular to each of the first axis and the second axis). The first DC electrode may be a substantially flat electrode arranged in a plane substantially parallel to the first surface. That is, the depth of the electrode may be substantially constant and may be significantly less than its length. The width of the electrode may be constant or may vary along its length.

[0022] The first direct current (DC) electrode is configured to receive a DC potential, for example, from a voltage source. The resulting electric field should repel the ions within the ion guide.

[0023] The first DC electrode may be wedge-shaped such that the first DC electrode may have a triangular cross-section. The inclined surface may connect the first end of the electrode to the second end of the electrode. An electrode having such a shape has the advantage that the electrode is easy to install in the device while still providing the required inclined surface. The simple shape of the electrode also enables the electrode to be constructed from low-cost materials such as laser-cut materials or stamped or etched materials.

[0024] The first DC electrode may be arranged in the same plane as the electrode array, i.e., along the first surface. This has the advantage that the DC electrode can be formed using the same substrate as one or more of the electrodes in the electrode array.

[0025] The second RF surface or counter electrode may be located at the second surface of the confinement device. The second surface may be opposite the first surface, i.e., may face the first surface in a direction along the third axis. The third axis is defined herein as perpendicular to each of the first axis and the second axis. The second surface (together with the first surface) may be configured to confine ions generally to a plane between the first surface and the second surface (i.e., when the ions travel through the confinement device). The ions will generally undergo an oscillatory motion as they travel through the confinement device, where their average position is generally described by the plane between the first surface and the second surface.

[0026] The first DC electrode may be located between the first surface and the second surface. For example, the first DC electrode may be located in the middle between the first surface and the second surface. The first DC electrode may be arranged such that it does not make direct contact with either the first surface or the second surface. This has the advantage that the DC electrode does not interfere with the function of the RF surface because the DC electrode does not mechanically or electrically interact with the RF surface. The first DC electrode may be separated from each RF surface in the RF surface by one or more spacers, where the spacers may be insulating spacers. The first DC electrode may be mounted to the ion guide using a mounting portion. The mounting portion may be located at the edge of the ion guide.

[0027] The first DC electrode may be one of a plurality of DC electrodes, where each of the plurality of DC electrodes is arranged in the same plane, e.g., such that a DC electrode layer is formed. Using a plurality of DC electrodes enables an additional force to be applied to the ions such that the ion path may be more complex because the ions can be guided in multiple directions at different points along the RF surface.

[0028] The DC electrode may be located at the periphery of the first surface or the second surface. This has the advantage that the DC electrode will not interfere with the function of the RF surface regardless of whether the DC electrode is in the same plane as the RF surface.

[0029] The ion guide may include one or more DC protection electrodes, where the one or more DC protection electrodes may be located between a first surface and a second surface (e.g., along a third axis) or in the same plane as the first surface or the second surface. The advantage of the DC protection electrode is that it can control the direction of the deflection caused by the DC electrode (e.g., in the case where the electrode is wedge-shaped). The DC electrode may be referred to as a wedge electrode or a wedge DC electrode. Thus, the DC electrode and the DC protection electrode can be used to push ions in a certain direction. The DC protection electrode and the wedge DC electrode have a repulsive potential applied to them. The voltage applied to the wedge DC electrode can be controlled to be different from the voltage applied to the protection electrode, i.e., greater than or less than the voltage applied to the protection electrode. By applying a voltage to the DC electrode that is greater than or less than the voltage applied to the DC protection electrode, the direction of the force provided by the DC electrode along the second axis can be controlled to be in a first direction along the second axis or in the opposite direction along the second axis (i.e., in a second direction). For example, the voltage applied to the wedge DC electrode can be greater than 20V, or less than 0V. In such an example, the voltage applied to the protection electrode can be 10V. The voltages applied to the protection electrode and the wedge DC electrode can be any other suitable values. The one or more DC protection electrodes may be located in the same plane as the DC electrode, or may be located in a plane different from the DC electrode. If the one or more DC protection electrodes and the DC electrode are located in the same plane, both the DC electrode and the one or more DC protection electrodes can be printed electrodes. However, in this case, the DC electrode will require a higher voltage compared to the case where the DC electrode and the one or more DC protection electrodes are in different planes.

[0030] The ion guide may include a second DC electrode, where the first DC electrode is located on a different side of the ion guide from the second DC electrode, such that the first DC electrode and the second DC electrode are located at different positions along the x-axis. In other words, the first DC electrode and the second DC electrode are located on different sides of the ion path. The ion path may be defined as the path that the ions will take based on the electrodes and the voltage applied to the electrodes. In other words, the first DC electrode and the second DC electrode are located on different sides of the inlet and the outlet, such that the inlet is located between the first DC electrode and the second DC electrode, and the outlet is also located between the first DC electrode and the second DC electrode. The ion guide may include a first DC protection electrode and a second DC protection electrode, and the first DC protection electrode and the second DC protection electrode may also be located on different sides of the ion path, i.e., on different sides of the inlet and the outlet. The first DC protection electrode may be positioned between the first DC electrode and the first surface, or the first DC electrode may be positioned between the first DC protection electrode and the first surface. The second DC protection electrode may be positioned between the second DC electrode and the first surface, or the second DC electrode may be positioned between the second DC protection electrode and the first surface.

[0031] Each of the DC electrodes in the DC electrode can be substantially aligned with one of the DC protection electrodes in the DC protection electrode, such that the first DC electrode and the first DC protection electrode can be substantially aligned along the first axis and the second axis (x-axis and z-axis), and the second DC electrode and the second DC protection electrode can be substantially aligned along the first axis and the second axis (x-axis and z-axis). The first DC electrode and the first DC protection electrode can be separated along the third axis (y-axis). The second DC electrode and the second DC protection electrode can be separated along the third axis. Each of the DC electrodes in the DC electrode can be electrically isolated from each of the DC protection electrodes in the DC protection electrode.

[0032] The first DC electrode can be an upper DC electrode, wherein the ion guide further includes a lower DC electrode such that the lower DC electrode is located between the upper DC electrode and the first surface (along the third axis). By having an upper electrode and a lower electrode, it is possible to control the ion direction by applying different voltages to the upper DC electrode and the lower DC electrode. The upper DC electrode and / or the lower DC electrode can be wedge-shaped. For terminological considerations, the electrodes are referred to as the lower electrode and the upper electrode. However, this does not limit the electrodes from having a height difference. The upper electrode and the lower electrode can be separated along the y-axis.

[0033] The upper DC electrode can be one of a pair of upper DC electrodes, and the lower DC electrode can be one of a pair of lower DC electrodes, where the electrodes in the pair of upper DC electrodes are located on different sides of the ion path in use. In other words, one of the pair of upper DC electrodes can be located on one side of the ion guide, and the other upper DC electrode of the pair of upper DC electrodes can be located on the other side (i.e., the opposite side) of the ion guide. The same applies to the lower DC electrodes. The lower DC electrode can be positioned between the pair of upper DC electrodes and the first surface, where each electrode in the pair of upper DC electrodes is substantially located at the same position along the x-axis as the electrode in the pair of lower DC electrodes. By having upper and lower electrodes on both sides of the ion guide, the ion direction (i.e., the ion path) can be further controlled by applying different voltages to some or all of the DC electrodes. The upper DC electrode and the lower DC electrode are configured such that the force exerted on the admitted ions can be controlled to be in a first direction along the first axis or in a second direction along the first axis. The upper DC electrode can be electrically isolated from each of the lower DC electrodes. The upper pair of DC electrodes is located in a plane parallel to the plane in which the lower pair of DC electrodes is located, and the electrodes of the upper pair are located on opposite sides of the ion guide along the first axis, and each electrode of the lower pair is located at the same position along the first axis as the corresponding electrode of the upper pair, such that the first pair of electrodes and the second pair of electrodes are substantially aligned in the x-direction and the z-direction. For example, in an embodiment where the electrodes are of different shapes, it should be understood that one of the upper electrodes can be substantially aligned with the corresponding lower electrode, however, due to the different shapes of the electrodes, the alignment may not be precise. For example, the electrodes of the upper pair can overlap or partially overlap with the corresponding electrodes of the lower pair.

[0034] The electrodes of the upper DC electrode pair and the lower DC electrode pair can be wedge-shaped. Using two pairs of wedge-shaped DC electrodes enables the direction of the ions to be further controlled.

[0035] The wedge-shaped DC electrodes can have different configurations. For example, the first electrode of the lower DC electrode pair can have an inclined surface that becomes closer (approaches) to the ion path in the x-direction, while the inclined surface of the second electrode of the lower DC electrode pair becomes farther from the ion path in the x-direction. Additionally or alternatively, the electrodes of the upper DC electrode pair can have surfaces with a configuration opposite to that of the corresponding electrodes of the lower DC electrode pair. By providing electrodes with opposite configurations, the ions can be guided in a first direction or a second direction in the z-direction by applying a repulsive potential to one or more of the electrodes.

[0036] The ion guide may include one or more outlets, and the inlet may be one of a plurality of inlets. The inlet and the outlet (i.e., the aperture) may be located on the ion guide such that they are each at different positions in the x-z plane. In other words, each of the apertures may be separated from each of the other apertures in the x direction and / or the y direction. In some examples, one or more outlets and the plurality of inlets (i.e., apertures) may be positioned such that each of the outlets and inlets is positioned adjacent to or at a corner of the ion guide. For example, the ion guide may include four apertures, where the apertures may be located at each corner of a rectangular ion guide. Ions entering one of the plurality of inlets may be ejected from any of the outlets by controlling the voltage applied to one or more of the DC electrodes.

[0037] The first DC electrode may be one of a plurality of DC electrodes, where each of the plurality of DC electrodes may be configured to be similar or identical to the first DC electrode. Each of the plurality of electrodes may be separated from the other electrodes of the plurality of electrodes along the x-axis. The plurality of electrodes may be substantially parallel to each other. In other words, the plurality of electrodes may be located in the same x-z plane. Each of the plurality of electrodes may have a surface that is inclined with respect to a first axis and a second axis. One or more of the plurality of electrodes may be arranged such that ions are pushed along the first axis in a first direction. One or more of the remaining plurality of electrodes may be arranged such that ions are pushed along the first axis in a second direction. In other words, the electrodes may be configured to push ions in different directions along the first axis. Thus, the plurality of DC electrodes may define a path that is not a straight line between the inlet (entry port) and the outlet (exit port), along which the ions are made to follow. In other words, the path between the inlet and the outlet is not a direct path, but rather the path between the inlet and the outlet may be curved. For example, the ion guide may define a meandering, tortuous, folded, and / or zigzag path. The path may be angled. For example, the path may include one or more angled portions, i.e., the path may include a plurality of segments, where each segment is connected to an adjacent segment at an angle. A repulsive potential may be applied to the DC electrodes such that when pushing the ions along the first axis (e.g., in the x direction), the ions are made to follow a curved path from the inlet to the outlet. This may be advantageous, particularly for an ion mobility separator, where a longer ion path may provide improved ion mobility resolution.

[0038] The ion guide may be configured to cause ions to follow an elongated ion path between the inlet and the outlet.

[0039] In another aspect, a beam switching device may be provided, which may include the ion guide described herein.

[0040] In another aspect, an ion mobility separator can be provided, which can include an ion guide as described herein.

[0041] In another aspect, an analytical instrument, such as a mass spectrometer, can be provided, which includes any one or more of the following: an ion guide as described herein, a beam switching device, and / or an ion mobility separator. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Aspects of at least one embodiment are discussed below with reference to the drawings, which are not intended to be drawn to scale. The drawings are included to provide illustration and further understanding of the various aspects and embodiments, and are incorporated into and form a part of this specification, but are not intended as a definition of the limits of the invention. In the drawings, each identical or nearly identical component illustrated in the various drawings is represented by a like numeral. For clarity, not every component will be labeled in every drawing.

[0043] Figure 1A An example of an electrode for an embodiment is shown;

[0044] Figure 1B An example of an electrode for an embodiment is shown;

[0045] Figure 2A 、 Figure 2B and Figure 2C show a top view, a side view, and a side view, respectively, of an ion guide according to an embodiment;

[0046] Figure 3 A perspective view of an ion guide according to an embodiment is shown;

[0047] Figure 4 A perspective view of an ion guide according to an embodiment is shown;

[0048] Figure 5 A top view of an ion guide according to an embodiment is shown;

[0049] Figure 6A A perspective view of an ion guide according to an embodiment is shown;

[0050] Figure 6B A diagram illustrating Figure 6A the path of ions within an ion guide is shown;

[0051] Figure 7 A diagram illustrating the path of ions within an ion guide according to an embodiment is shown; and

[0052] Figure 8 A mass spectrometer incorporating an ion guide according to an embodiment is shown. Detailed Embodiments

[0053] The present disclosure will now be described with respect to specific embodiments. The embodiments described herein are not intended to be limiting, but rather for illustrative purposes.

[0054] Figure 1A A first example of an electrode configuration 100A within an ion deflector configured in accordance with the present disclosure is shown. As Figure 1A shown, in this configuration, the ion path 106 (i.e., in the direction in which the ions travel) is initially in the direction along a first axis. The ions are guided in a first direction due to a first force 104 along the first axis, where it should be understood that guiding the ions in the first direction may not result in the ions traveling in the first direction. Instead, the ions are pushed in the first direction, which causes the direction of the ions to have a component in the first direction, where the direction of movement of the ions may also have a component in a second direction such that the ions move at an angle with respect to both the first and second directions. As will be described herein, the first force 104 acting on the ions is in the first direction, i.e., along the first axis, which may be due to a DC gradient or a DC traveling wave applied to the RF electrode array (as will be described herein), or due to a gas force (e.g., due to a gas jet or an additional gas flow).

[0055] As Figure 1A shown, there is also a DC electrode 102a that includes a surface 103 that is inclined with respect to the first axis and a second axis, where the second axis is in a direction orthogonal to the first axis. Thus, the ions traveling along the first axis are traveling at an angle with respect to the surface of the electrode 102a. The ions are pushed by the first force and interact with the inclined surface 103 of the electrode 102a. A second force 108 is applied to the ions by the electrode and its inclined surface 103, where the second force has a component along the second axis such that the ion path 106 is altered and the ions move in the second direction. The second direction (i.e., the subsequent direction of travel of the ions) may be different from the direction of the second force 108. In Figure 1A the example shown, the initial path of the ions is along the first axis, and the subsequent path of the ions 106 is substantially parallel to the inclined surface of the electrode 103 such that the subsequent ion path is at an angle with respect to both the first and second axes. However, the direction of the force 108 is along the second axis that is orthogonal to the first axis. It should be understood that, and for example with respect to Figure 3 as described, the initial path of the ions as well as the subsequent path of the ions may be in a direction different from the direction described with respect to Figure 1A as described.

[0056] Figure 1B A second example of an electrode configuration 100B within an ion deflector configured in accordance with the present disclosure is shown. The initial and subsequent movement of the ions is the same as Figure 1AThe same as described above. The first force and the second force have the same direction as that described with respect to Figure 1A the direction described above. Figure 1A and Figure 1B The difference between the configurations of and lies in the shape of the electrode 102b. In Figure 1B the example shown, the electrode has a wedge shape such that it has a first end 105a and a second end 105b, where the first end has a first width and the second end has a second width. The width of the first end is greater than the width of the second end. The first end 105a has a face pointing along the second axis, and the second end 105b has a tip pointing along the second axis. Thus, the electrode 102b has a triangular cross-section such that the electrode 102b has a surface 103 that is inclined with respect to the first axis and the second axis, where the second axis extends in a direction orthogonal to the first axis. Thus, the inclined surface 103 connects the first end 105a and the second end 105b of the electrode 102b. The electrode is oriented such that the inclined surface 103 interacts with the ion path 106. For the same reason as that described with respect to Figure 1A the same as described above, a second force 108 is applied to the ions. Thus, although Figure 1B the electrode 102b of has a different shape from Figure 1B the electrode 102a of, since the two electrodes are oriented such that they have inclined surfaces that result in forces that interact with the ions, the effect on the ions is substantially the same.

[0057] It should be understood that although the embodiments described herein relate to electrodes having a wedge shape, the electrodes can be of any shape having a suitable inclined surface for applying the desired force to the ions. In other words, the electrodes can be of any shape having a surface inclined with respect to the first axis and the second axis. For example, the electrode can have a trapezoidal cross-section or can have a rectangular cross-section. Thus, although some examples mention wedge-shaped electrodes, any suitable-shaped electrode can be used in the examples described herein to achieve the same technical effect. Thus, instead of wedge-shaped electrodes, such non-wedge-shaped electrodes can be combined with any of the examples described herein.

[0058] As mentioned herein and best illustrated in Figure 3 and Figure 4 , the ion guiding system of the embodiments is described with respect to a three-dimensional coordinate system such that the ion guiding system has an x-axis, a y-axis, and a z-axis. As Figure 3 and Figure 4 shown, the RF electrodes described herein have a length extending along the z-axis. The RF electrodes also have a width extending along the x-axis, where the x-axis is perpendicular to the z-axis. The y-axis is perpendicular to both the x-axis and the z-axis and defines the height or depth of the device. These axes will be used herein to define features.

[0059] Figure 2A ,Figure 2B and Figure 2C illustrates an ion guide 200 that includes two RF surfaces 216a and 216b and at least one DC electrode 202. As described herein, the RF surfaces include a plurality of RF electrodes that extend in the x-z plane.

[0060] The RF surfaces described herein may also be referred to as RF blankets or RF ion blankets. The RF surfaces are formed by a plurality of electrodes that have substantially planar surfaces and are configured to receive an RF voltage such that there is a voltage phase difference between adjacent electrodes among the plurality of electrodes. In other words, one or more (or each) of the plurality of electrodes may have a substantially planar face. The RF surface can thus generate a substantially planar RF pseudopotential surface parallel to the RF surface when receiving the RF voltage. Even if not all of the plurality of electrodes each have a substantially planar face, it can be considered that the plurality of electrodes together have a substantially planar surface. The planar surface may extend along a first axis and a second axis (e.g., the x and z axes), and the first axis and the second axis may be perpendicular to each other.

[0061] The RF surface can be substantially planar, but does not need to be completely flat. For example, the electrodes may include recesses or protrusions or be wedge-shaped to direct or compress an ion beam.

[0062] Ions traveling through an ion guide according to one example of the examples described herein are constrained by the constraint means disclosed herein. The constraint means generally constrains the ions to a plane, where the plane is substantially parallel to the first RF surface, i.e., the plane is substantially parallel to the x-z plane formed by the plurality of electrodes. In some embodiments, the constraint means includes a second surface, i.e., a top surface, where the second surface is positioned opposite the RF surface. Thus, a constraint field can be provided by the combination of the first RF surface and the second RF surface. The first surface and the second surface may also be referred to as a bottom plate and a top plate. The first surface and the second surface are positioned relative to each other such that the first surface and the second surface substantially overlap. Ions can travel through the ion guide system while being constrained within the ion guide system. The ions will generally experience an oscillatory motion as they travel through the ion guide system, where their average position is generally described by the plane.

[0063] Although the embodiments herein will be described as having a second RF surface as the top surface, the second surface may alternatively be a DC repelling plate. Thus, the second constraint field can be provided by the combination of the RF surface and the DC repelling plate. The same technical considerations apply to using a DC repelling plate, and thus any embodiment described herein can be implemented with a DC repelling plate instead of the second RF surface. In an ion guide system that includes a DC repelling plate (also referred to as a DC counter electrode), it is possible to taper the RF quadrupole electrodes into the DC surface.

[0064] The DC repelling plate is configured to apply a repelling voltage that repels ions towards the RF surface. The DC repelling plate is thus configured to confine the ion beam between the repelling plate and the RF surface. The repelling plate can be configured to prevent the ion beam from approaching the repelling plate, thereby avoiding contamination and charging effects on the repelling plate. Thus, by using the confinement device, the ions substantially reside in and travel in a plane above the lower RF surface. In embodiments where the confinement device includes a second surface (e.g., a DC repelling plate or a second RF surface), the ions reside in and travel in a plane between the lower RF surface and the top surface.

[0065] In Figure 2A the illustrated embodiment, one or more DC electrodes 202 are located between two RF surfaces such that the one or more DC electrodes are sandwiched between the RF surfaces. The one or more DC electrodes are positioned around the perimeter of the RF surface such that the central portion of the RF surface is not covered by the DC electrodes in the y - direction. In other words, the one or more DC electrodes cover a smaller area than the RF surface such that a portion of the RF surface is not covered by the one or more DC electrodes.

[0066] As Figure 2A illustrated, the ion guide can include one or more DC electrodes. For example, in the ion guide 200, there are two DC electrodes 202a and 202b. The DC electrodes 202a and 202b are positioned opposite to each other such that both of them are in the same plane. The plane in which the DC electrodes are located is parallel to the plane in which one or more RF electrodes are located, i.e., in a plane parallel to the RF surface 216. The DC electrodes do not make physical contact such that a gap is formed in the front of the device that provides an entrance 218, and a gap is formed in the back of the device that provides an exit 220 of the ion guide. The entrance and the exit can be entrance holes and exit holes, however, the entrance and the exit do not need to be holes. Ions are allowed to enter the ion guide via the entrance 218, and the ions travel along the x - axis such that the ions travel towards the opposite side of the ion guide where the exit 220 is located. The DC electrodes can be shaped such that the entrance and the exit of the ion guide are not in a straight line, i.e., the exit can be positioned at a different location along the z - axis from the entrance. Thus, ions that initially travel in the x - direction from the entrance will be required to move in the z - direction in order to leave the ion guide. The DC electrodes 202a and 202b include one or more inclined surfaces such that the ions interact with one or more surfaces of the one or more DC electrodes. The DC electrodes in this embodiment have a wedge - shaped portion, however, the DC electrodes also have surfaces parallel to the first axis. In other words, the DC electrodes have one or more surfaces that are inclined with respect to the first axis and the second axis, thereby forming a wedge - shaped portion, and have one or more surfaces parallel to the first axis or the second axis. Figure 2AThe DC electrodes shown include wedge-shaped portions on opposite sides of the RF surface, where the opposite sides are the same side that includes the inlet hole and the outlet hole. Surfaces parallel to the first axis are on the opposite sides, where these two sides are different from the two sides where the wedge-shaped portions are located.

[0067] The DC electrodes 202a and 202b provide a force on the ions that deflects the path of the allowed-in ions such that ions can be ejected from the ion guide through outlets at different positions along the z-axis compared to the inlet where the ions are allowed into the ion guide. In other words, the outlets are offset from the inlet along the z-axis. The ion path is thus not straight, i.e., the ions travel not only in the x-direction but also in the z-direction as well as the x-direction. The ion path is substantially constant in the y-axis, i.e., the ions travel in a plane substantially parallel to the plane in which the RF electrodes extend. The DC electrodes 202a and 202b may also be referred to as guard electrodes, where one or more guard electrode plates incorporate wedge-shaped electrodes, i.e., the guard electrode plates include one or more surfaces relative to the first axis and the second axis as described herein. As described herein, the ion guide may include DC electrodes and DC guard electrodes, or alternatively, the DC electrodes having wedge-shaped portions may also be DC guard electrodes. By deflecting the ions between injecting ions into the ion guide and ejecting ions from the ion guide, it is possible to separate the ions from neutral contaminants because neutral molecules are not guided along the z-axis and thus will not be ejected from the ion guide through the outlet.

[0068] Figure 2B A side view of the ion guide 200 is shown, where one or more DC electrodes are plate-shaped electrodes and one or more electrodes are suspended between two RF surfaces by insulating spacers. In Figure 2B a single DC electrode is shown, however, it should be understood that there may be multiple DC electrodes that are not visible in the side view because each of the multiple DC electrodes is in the same z-x plane. As Figure 2B shown, one or more DC electrodes 202 are mechanically connected to each of the RF surfaces 216a and 216b by using nuts 210, screws 212 that fix (i.e., stack the surfaces) the two RF surfaces and one or more DC electrodes together. The stack of surfaces may include two sets of nuts and bolts such that the nuts and bolts are separated along the electrodes. One or more DC electrodes are spaced apart from each of the RF surfaces by two or more sets of spacers 214, i.e., separated, where the spacers may be insulating spacers. There may be two spacers in each set that are attached to either surface of the DC electrode and subsequently attached to either surface of the RF surface. Alternatively, one or more DC electrodes may have holes extending through the depth of the one or more DC electrodes, i.e., apertures, such that the spacers may be continuous and pass through the one or more DC electrodes. InFigure 2A Such holes are shown in Figure 2A , where the holes, i.e., spacer points 214, are shown. Thus, there may be only one spacer in each group. The two groups of spacers are separated along the electrodes such that the spacers are in line with the nuts and bolts of that group. The spacing of the nuts, bolts, and spacers along the electrodes results in one or more DC electrodes being spaced from the RF surface by the same distance along the entirety of one or more DC electrodes.

[0069] Figure 2C Another example of a suspended DC electrode is shown, where the DC electrode is suspended (i.e., attached or mounted to the ion guide) by plastic mounts at each side of the device. As Figure 2C shown, the first RF surface 216a and the second RF surface 216b, and one or more DC electrodes 202 are mounted to the mounting portion 222. The mounting portion may be located at the edge of the ion guide 200. The mounting portion 222 is formed of an insulating material, for example, the mounting portion may be plastic. Alternatively, the mounting portion may be composed of any material suitable for mounting the RF surface and the DC plate electrodes to the ion guide 200.

[0070] Multiple DC electrodes 202 are shown suspended in Figure 2A , Figure 2B and Figure 2C such that the DC electrodes form a layer in a plane different from the plane in which the RF surfaces are located. In other words, one or more DC electrodes may be located between a first surface and a second surface, as described herein. The suspended DC electrodes (i.e., the DC electrode layer) may be located in a plane substantially parallel to the plane formed by the RF electrodes. However, it should be understood that the DC electrodes in any of the embodiments discussed herein may instead be located in the same plane as one or more RF electrodes, i.e., in the same plane as the RF surfaces. The DC electrodes may be printed on the same surface as the RF electrodes, i.e., the same substrate, such that the DC electrodes are formed from the same surface as the multiple RF electrodes. Alternatively, the DC electrodes may be solid electrodes mounted to the same plane as the RF electrodes, or may be mounted outside the plane of the RF electrodes.

[0071] An advantage provided by the shape of the electrodes described herein is that they can be constructed from low-cost materials such as laser-cut materials, or they can be stamped or etched.

[0072] Figure 3 An ion guide 300 configured for use in a beam switching device is shown. As described herein, the ion guide includes a first RF surface and a second surface, where the second surface may be a second RF surface or a DC repelling plate. However, for clarity, the second RF surface is not illustrated in Figure 3 . As regarding Figure 2A , Figure 2B andFigure 2C As described, the ion guide includes an inlet (i.e., an entrance) and an outlet (i.e., an exit). In Figure 3 the illustrated embodiment, the ion guide includes a plurality of holes 320a, 320b, 318a, and 318b, each of which is located in a corner of the RF surface. Two holes are located on a first side of the ion guide, and two holes are located on a second side of the ion guide, where the first side and the second side are opposite sides. The holes are configured to allow ions to enter or extract ions. The ion guide may include one inlet hole and one outlet hole, or the ion guide may include two inlet holes and two outlet holes. It should be understood that any hole can be configured as an outlet hole or an inlet hole such that ions can enter and exit any of the holes depending on the direction of the DC gradient, traveling wave, or gas force and the orientation of the DC electrodes. For purposes of illustration, Figure 3 the description will be made with respect to inlet holes 318a and 318b and outlet holes 320a and 320b.

[0073] The ion guide 300 includes a first RF surface that includes a plurality of RF electrodes extending in the z direction (i.e., along the second axis). The plurality of RF electrodes also have a width in the x direction (i.e., along the first axis). The ion guide further includes two DC electrodes 302a and 302b that are oriented such that they have surfaces that are inclined with respect to the x-axis and the z-axis (i.e., inclined with respect to the first axis and the second axis), where in this example, the DC electrodes have a wedge shape. The wedge-shaped DC electrodes are located at the periphery of the device, and the wedge-shaped DC electrodes extend in the z direction such that both the wide end and the narrow end face the z direction. The DC electrodes 302a and 302b are located on opposite sides of the ion guide, where these opposite sides are different from the sides where the holes are located. In other words, the holes are located on a first side and a second side of the RF surface, and the DC electrodes are located on a third side and a fourth side of the RF surface. The holes are positioned such that ions allowed to enter via any of the holes initially travel along the second axis, while the DC electrodes are positioned such that ions traveling along the first axis will reach the DC electrodes.

[0074] As described herein, ions are guided along the first axis, and thus ions allowed to enter via Figure 3 any of the holes are pushed in the direction along the first axis after they have entered the ion guide. The inclined surfaces of the DC electrodes are inclined with respect to the x-axis, and ions traveling in the x direction due to a first force will interact with the inclined surfaces of the electrodes 302a and 302b. As Figure 3As shown, in an embodiment where the ion guide includes two DC electrodes, the inclined surfaces of the two electrodes are skewed in opposite ways. In other words, in an example where the DC electrodes are wedge-shaped, the first electrode has a width in the x-direction that decreases as it increases in the z-direction, while the second electrode has a width in the x-direction that increases as it increases in the z-direction. Thus, one DC electrode has a wide end at the side of the RF surface adjacent to the inlet hole, while the other DC electrode has a thin end at the side of the RF surface adjacent to the inlet hole. Accordingly, the distance between the ion path and one DC electrode decreases as the distance along the z-axis (i.e., towards the outlet hole) increases, while the distance between the ion path and the other DC electrode increases as the distance along the z-axis increases.

[0075] The ion guide 300 further includes two DC guard electrodes 324a and 324b, each of which is overlaid by one of the DC electrodes 302a and 302b. In other words, the DC guard electrodes 324a and 324b are positioned adjacent to the first RF surface 316, and the DC electrodes 302a and 302b are positioned adjacent to the DC guard electrodes. In other words, the DC guard electrodes are located between one or more DC electrodes and the first RF surface. However, it should be understood that the DC guard electrodes could instead be located between one or more DC electrodes and a second surface (e.g., a second RF surface).

[0076] As described above, the two DC electrodes are located on opposite sides of the RF surface, where the opposite sides are different from the side where the hole is located. The DC guard electrodes are thus located on opposite sides, where these sides are the same sides as where the DC electrodes are located. The DC guard electrodes are located in a plane parallel to the plane in which the wedge-shaped DC electrodes are located. Thus, each of the DC guard electrodes is substantially aligned with one of the plurality of DC electrodes. As Figure 3 shown, the DC guard electrodes are rectangular in shape. However, the DC guard electrodes can be of any suitable shape.

[0077] In one use of the ion guide of FIG. 300, ions are allowed to enter through inlet 318a. The ions are allowed to enter in the z-direction via inlet 318a. A first force is applied to the ions in a first direction, where the force is applied by a DC traveling wave, a DC gradient, or a gas force. The first force is in the x-direction, and thus the ions that are allowed to enter are pushed in the x-direction. In other words, the initial force acting on the ions is in the x-direction. The ions are pushed in the x-direction, however the ions may already have inertia, and thus the ions may move not only in the x-direction. In other words, the ions are pushed in the first direction, however the ions may move in a direction different from the first direction. Instead, the ions may move along a path that has components in both the x- and z-directions. In other words, the path may not be a straight line, but may be a curved path or an angled path, as described in other embodiments herein. In Figure 3 the illustrated embodiment, the ions travel in an arc, where the ions initially travel in the z-direction and are then pushed by the first force in the x-direction.

[0078] Due to the first force, the ions travel towards the inclined surface of DC electrode 302b, where the DC electrode is located on the side of the RF surface opposite the inlet through which the ions are allowed to enter. In other words, in this example, the inlet is on the back of the device and the DC electrode is on the front of the device. A DC is applied to electrode 302b, where the DC is offset relative to the RF surface to repel the ions, but may be positive or negative relative to the DC guard electrode with which it overlaps. Thus, in use, the potential of the guard electrode is perturbed and a DC gradient along the z-axis is produced. Thus, the ions are guided in the direction along the z-axis towards the exit hole. In other words, a second force is produced, where the second force is orthogonal (i.e., perpendicular) to the first force. In other words, the second force has a component along a second axis, where the second axis is orthogonal to the first axis, and the first axis is the direction in which the ions are initially pushed. Thus, as Figure 3 shown, the ions are pushed along the x-axis and then along the z-axis, and thus the ions follow a curved path to exit hole 320b.

[0079] Ion guide 300 thus causes ions to be allowed to enter into inlet 318a and be ejected from outlet 320b, where the outlet is offset from the inlet in the x-direction. It should be understood that the ions may be allowed to enter any one of the other holes, and the same technical considerations will apply to provide a force that causes the ions to exit the ion guide through the hole. The second force may point in the positive z-direction or the negative z-direction due to the orientation of the inclined surface described herein, i.e., the force may point Figure 3 to the left or right such that the ions may be guided by the force away from a hole on the opposite side of the RF surface, as Figure 3as indicated by the arrows in. For example, ions allowed to enter the lower right hole can leave the RF surface via the upper left hole, and ions allowed to enter the upper right hole can leave the RF surface via the lower left hole.

[0080] An advantage provided by such a system is that a separate DC electrode can push ions in only one direction, because setting it to the opposite polarity of the ions will pull the ions into the electrode. Thus, the use of a DC guard electrode solves this problem. Instead of having one or more DC guard electrodes, repulsion can be provided by offsetting one or more of the last RF electrodes in the RF surface with a positive potential, thereby providing a mechanically simpler configuration.

[0081] As Figure 3 shown, the wedge-shaped DC electrode and its inclined surface extend in the z-direction along the width of the RF surface, such that the wedge-shaped DC electrode covers the entire width of the device, or almost the entire width of the device. The size of the wedge-shaped DC electrode and the applied voltage can depend on the positioning of the DC guard electrode. For example, the DC guard electrode can have a voltage of +10V, and thus the wedge-shaped DC electrode can have a voltage of 0 to 20V to create a DC gradient in either direction. Part or all of the wedge-shaped DC electrode can overhang the DC guard electrode, or be recessed. However, it is beneficial that the wedge-shaped DC electrode and the DC guard electrode are neither overly overhanging nor overly recessed with respect to the DC electrode to achieve a balance between the two potential sources.

[0082] Figure 4 Another example of an ion guide 400 is shown. The ion guide 400 includes the same features as the ion guide 300. However, the ion guide 400 includes a second pair of wedge-shaped DC electrodes 402c and 402d instead of including the two DC guard electrodes as described above. Thus, the ion guide 400 will be described as including an upper electrode pair (e.g., an upper wedge-shaped DC electrode pair) 402b and 402a and a lower electrode pair 402d and 402c (e.g., an upper wedge-shaped electrode pair). As described herein, the DC electrodes in this example are wedge-shaped, however any suitable shape of electrode (e.g., having a surface inclined with respect to a first axis and a second axis) can be used in this example. The upper wedge-shaped electrode pair is located in a plane parallel to the plane in which the lower wedge-shaped electrode pair is located. The upper wedge-shaped electrode pair is positioned substantially in line with the lower wedge-shaped electrode pair such that each electrode in the upper wedge-shaped electrode pair overlays each electrode in the lower wedge-shaped electrode pair. In other words, the upper wedge-shaped electrodes are located in the same position as the lower wedge-shaped electrodes with respect to the x and z axes. However, as Figure 4 shown, the electrodes of the lower wedge-shaped electrode pair are oriented such that the wide ends of the lower wedge-shaped electrodes are on the side of the RF surface opposite to the wide ends of the upper wedge-shaped electrodes on the z-axis.

[0083] As described with respect to Figure 3 above, one electrode of the upper wedge electrode pair has a width that decreases with distance along the z-axis, while the other electrode of the upper wedge electrode pair has a width that increases with distance along the z-axis. The same applies to the lower electrode pair, where the electrode widths decrease or increase in the opposite direction to the upper electrode pair, as Figure 3 shown. Thus, the inclined surfaces of the upper electrode pair are skewed in the opposite direction to the inclined surfaces of the lower electrode pair. A pair of additional electrodes provides a potential gradient to the guard DC electrodes of the ion guide 300 in an alternative manner. A stronger repulsive potential can be applied to one of the additional electrodes to create a potential gradient in one of these directions.

[0084] A buffer gas can be applied to Figure 3 and Figure 4 the device described, for example, a buffer gas of greater than or equal to 1×10 -3 mbar can be applied to cool the ions. Cooling the ions has the advantage that the ions have reduced kinetic energy and thus remain in the ion guide after being allowed to enter, and their movement can be controlled by the various electric fields generated by the ion guide. In addition, ions with reduced kinetic energy are more easily focused and thus provide better transmission and reduced unwanted fragmentation when used in an ion guide, as described herein.

[0085] Figure 5Shows an example of an ion guide according to an embodiment. The ion guide 500 provides an increased path length for ions, where the path length is increased by creating a meandering path that the ions follow. In other words, the ion guide is used to create an elongated ion path. The ion guide can be used for ion mobility separation. The ion guide includes a first RF surface 516 and a second surface (not shown) as described herein. The ion guide also includes an inlet 518 and an outlet 520 located on opposite sides of the ion guide, such that the inlet and the outlet are at the front and the back of the device, i.e., at the front and the back of the RF surface. The ion guide includes a plurality of wedge-shaped DC electrodes, two of which have been labeled 502a, 502b. The plurality of wedge-shaped DC electrodes are located on a first side of the RF surface 516, and the plurality of wedge-shaped DC electrodes are located on a second side of the RF surface 516. The wedge-shaped DC electrodes extend from different sides to the side where the inlet and the outlet are located. In other words, the inlet and the outlet can be considered to be on the first and second sides of the RF surface, and the wedge-shaped DC electrodes are considered to extend from the third and fourth sides of the RF surface. Each of the wedge-shaped DC electrodes in the plurality of wedge-shaped DC electrodes is oriented such that their wide ends are at the periphery of the RF surface, and their thin ends are above the RF surface. Thus, the wedge-shaped DC electrodes located on one surface have a width that decreases with distance in the z direction, while the wedge-shaped DC electrodes on the opposite surface have a width that increases with distance in the z direction.

[0086] The wedge-shaped DC electrodes are offset from each other such that the wedge-shaped DC electrodes located on the first side of the RF surface are at different positions along the x-axis compared to the positions of the wedge-shaped DC electrodes on the second side of the RF surface. Thus, the line of sight from the inlet 518 to the outlet 520 is interrupted (i.e., blocked) by the plurality of wedge-shaped DC electrodes, such that it is not possible for ions to travel in a straight line from the inlet to the outlet. Thus, the ion path 506 must bend for the allowed ions to reach the outlet. Thus, a long DC channel is created. Each of the wedge-shaped DC electrodes in the plurality of wedge-shaped DC electrodes has an inclined surface that interacts with the ions traveling along the ion path. Thus, the inclined surface of each of the wedge-shaped DC electrodes in the plurality of wedge-shaped DC electrodes faces the inlet aperture 518.

[0087] Ions are allowed to enter the ion guide in the x-direction. By applying a DC gradient or a traveling wave to the RF electrode array, or by applying a gas force to the ions, the ions move in the x-direction. Thus, an initial force is applied to the ions, which guides these ions in the x-direction. In an example where the ions move in the x-direction by a traveling wave, the traveling wave is superimposed on the RF electrodes and runs with an additional superimposed RF of 4+ phases, where each phase differs by 90 degrees and runs at a lower voltage and frequency than the trapping waveform. For example, the traveling wave can be from 5V to 50V and the frequency is from 50kHz to 250kHz. The traveling wave can also be implemented as a series of applied transient DC pulses, giving the impression that the DC pulses move along the electrode series, usually moving up 1 or 2 electrodes at a time and down 3 to 6 electrodes.

[0088] A second force is applied to the ions by each of the wedge-shaped DC electrodes in the wedge-shaped DC electrode, where the second force is orthogonal to the first force. Thus, the ions initially guided in the x-direction are guided by the second force in the z-direction. Since all of the wedge-shaped DC electrodes have a width that decreases from the edge of the RF surface towards the center of the RF surface, the force generated by the electrodes extending from one side of the RF surface is in the opposite direction to the force generated by the electrodes extending from the opposite side. Thus, the ions feel a force in the positive z-direction due to one wedge-shaped DC electrode 502a, and subsequently, the ions feel a force in the negative z-direction due to the opposite wedge-shaped DC electrode 502b. Thus, the ions follow a meandering path in which the ions move in the positive and negative directions. However, the ions continue to move in the positive direction relative to the x-axis, i.e., the ions always move from the inlet hole to the outlet hole. In this way, the length of the ion path is increased without requiring a longer ion guide. It should be understood that although Figure 5 the ion guide is shown as including five wedge-shaped DC electrodes, the number of electrodes can be greater than or less than the number shown to increase or decrease the length of the ion path 506.

[0089] Figure 6A is shown Figure 5 the ion trajectory simulation of the device 500. Figure 6B is shown the ion path of the ions injected into the ion guide 500. Figure 5 The features of the device in Figure 5 are the same as the features of the device described with respect to Figure 5 . Thus, these features are labeled the same as in Figure 5 and will not be described in detail herein. Instead, the reader is referred to the description of the features related to Figure 6A . In the simulation device shown in Figure 6AThe model shown consists of two opposite stacks of 4 mm wide RF electrodes, where the opposite stacks are separated by 10 mm, and where each electrode in series carries the applied 2 MHz, 250 V 峰-峰 RF in antiphase. A 1 V / mm Dc gradient is superimposed to drive the ions in the x direction. A series of seven 20 mm wide, 80 mm long wedge electrodes with +10 V applied are arranged as described with respect to Figure 5 stated. The pressure of the buffer gas is set to 1×10 -2 mbar. However, it should be understood that for ion mobility applications, the buffer gas can be increased to greater than or equal to 1 mbar.

[0090] In the simulation, m / z 200 ions are introduced into the ion guide 500. As Figure 6B shown, the ions follow a meandering (i.e., zigzag or serpentine) path. In other words, the ion path has a curved shape, where the ions have a path that alternates between traveling in the positive z direction and the negative z direction.

[0091] The ion mobility separator can include an ion guide according to the embodiments described herein, such as the ion guide 500. It should be understood that such an ion mobility separator will be required to have an accumulation or trapping region in front of the device, where the accumulation or trapping region can be any suitable known region that is not described herein.

[0092] Figure 7 Another simulated ion path of the ion guide 500 is shown. In this simulation, the wedge electrodes have a thickness of 2 mm and a low repulsion potential of +10 V, while the superimposed DC gradient is set very high, for example equal to or greater than 100 V. As Figure 7 shown, when the ions flow around the wedge electrodes, the repulsion is not sufficient to block the ion flow, but effectively splits the RF channel into 2 channels. This is shown in Figure 7 where the ion beam is effectively fragmented into two and then recombined.

[0093] Figure 8 A mass spectrometer 800 incorporating an ion guide according to the embodiments described herein is shown. Figure 8The mass spectrometer is combined with an ion guide 500, in which an elongated path is formed by a series of wedge-shaped electrodes. The mass spectrometer may include some or all of the features of the mass spectrometer 10 described in US10699888B2, which is hereby incorporated by reference in its entirety. The mass spectrometer of the present disclosure includes an ion mobility separator combined with an ion guide of the present disclosure (such as the ion guide 500), wherein the meandering path of the ion guide separates ions by mobility, mass-to-charge ratio (m / z), and charge state. As described herein, ions follow a meandering path due to electrodes having one or more inclined surfaces, and the electrodes guide the ions traveling through the ion guide by several forces. The ion guide not only adds ion mobility information to mass analysis but also works in combination with a quadrupole to limit the proportion of ions that become deposited on the rods of the quadrupole.

[0094] It should be noted that the mass spectrometer described herein and of the present disclosure Figure 8 The mass spectrometer shown has the same technical effects and considerations as the mass spectrometer 10 described in US10699888B2. The difference between the mass spectrometers of the present application and US10699888B2 is that the mass spectrometer 800 of the present invention includes an ion mobility separator according to an embodiment of the present disclosure. This feature will be described herein with respect to the mass spectrometer. However, for a complete description of the remaining features shown Figure 8 the reader may refer to US10699888B2, the corresponding features of which have the same effects and purposes as the features shown Figure 8 shown.

[0095] Ions are generated from a sample by an electrospray ion source 830 and guided by a capillary 856 into an RF-only S lens 832, also known as an ion funnel. In this case, the ion funnel acts as an accumulation device for pulsed introduction into the ion mobility separator 500, wherein the ion mobility separator includes an ion guide according to an embodiment of the present disclosure. Alternatively, instead of an ion funnel, this functionality can be incorporated into the ion mobility separator itself by using gate electrodes. The ions enter the ion mobility separator 500 via a calibrant source 854 and travel through the ion guide, thereby becoming separated by mobility and substantially by mass-to-charge ratio (m / z) and charge state. The ions are transferred from the ion mobility separator 500 to a mass selector in the form of a quadrupole mass filter 852. The quadrupole mass filter 852 is typically but not necessarily segmented and acts as a bandpass filter, allowing selected mass numbers or a limited mass range to pass while excluding ions of other mass-to-charge ratios (m / z). The filter can also operate in an RF-only mode, in which the filter has no mass selectivity, i.e., it transmits substantially all m / z ions. For example, the quadrupole mass filter 852 can be controlled by a controller to select a certain range of mass-to-charge ratios that are allowed to pass while filtering out (attenuating) other ions in the precursor ion stream. AlthoughFigure 8 A quadrupole mass filter is shown, but those skilled in the art will appreciate that other types of mass selection devices may also be suitable for selecting precursor ions within the mass range of interest. For example, the ion separator depicted in US-A-2015287585, the ion trap depicted in WO-A-2013076307, the ion mobility separator described in US-A-2012256083, the ion gate mass selection device described in WO-A-2012175517, or the charged particle trap described in US799223, the above are incorporated herein by reference in their entirety. Those skilled in the art will appreciate that other methods of selecting precursor ions based on ion mobility, differential mobility, and / or transverse modulation are also suitable.

[0096] The method known as synchronous precursor scan (SPS) can also be used to perform the isolation of multiple ions of different masses or mass ranges in an ion trap. Additionally, in some embodiments, more than one ion selection device or mass selection device may be provided. For example, another mass selection device may be provided downstream of the fragmentation chamber 836. In this way, MS 3 or MS n scans (usually using a ToF mass analyzer for mass analysis) can be performed when necessary.

[0097] The mass-filtered ions are directed from the quadrupole mass filter 852 to a curved linear ion trap (C-trap) 834 via a charge detector 833. The cooled ions are trapped as a cloud towards the bottom of the potential well and then orthogonally ejected from the C-trap towards the second mass analyzer 850. As Figure 8 shown, the second mass analyzer is a Fourier transform mass analyzer, such as an Orbitrap mass analyzer 850, for example, the Orbitrap sold by Thermo Fisher Scientific, Inc. TM mass analyzer. The Fourier transform mass analyzer 850 has an off-center injection hole, and the ions are injected into the Orbitrap mass analyzer 850 as a coherent group through the off-center injection hole. Then, the ions are trapped within the Orbitrap mass analyzer by a super-logarithmic electric field, and the ions perform back-and-forth motion in the longitudinal direction while orbiting around the inner electrode.

[0098] The moving axial (z) component of the ion group in the Orbitrap mass analyzer is (more or less) defined as a simple harmonic motion, where the angular frequency in the z direction is related to the square root of the mass-to-charge ratio of a given ion species. Therefore, over time, the ions are separated according to their mass-to-charge ratio.

[0099] In the above configuration, in the absence of fragmentation, sample ions (more specifically, a mass range segment of sample ions within the mass range of interest selected by quadrupole mass filter 852) are analyzed by an orbitrap mass analyzer 850. The resulting mass spectrum is represented as MS1.

[0100] Although an orbitrap mass analyzer 850 is shown in Figure 8 , other mass analyzers may alternatively be used, including other Fourier transform mass analyzers. For example, a Fourier transform ion cyclotron resonance (FTICR) mass analyzer can be used as the mass analyzer for MS1 scans. Mass analyzers such as orbitrap mass analyzers and ion cyclotron resonance mass analyzers can be used in embodiments even in cases where other types of signal processing different from Fourier transform are used to obtain mass spectrometry information from transient signals (see, e.g., WO 2013 / 171313, Thermo Fisher Scientific).

[0101] Ions in the orbitrap mass analyzer are detected by using an image current detector (not shown), which generates a "transient" in the time domain containing information about all ion species as the ion material passes through the image current detector. This transient then undergoes a fast Fourier transform (FFT), resulting in a series of peaks in the frequency domain. Based on these peaks, a mass spectrum representing the abundance / ion intensity versus m / z can be generated.

[0102] In the second operating mode of the C-trap, ions that pass through the quadrupole mass filter and enter the C-trap can also continue their path through the C-trap and the fragmentation chamber 836, which can be an "ion routing multipole" (IRM) collision cell. Thus, the C-trap effectively acts as an ion guide in the second operating mode. Alternatively, the cooled ions in the C-trap 834 can be ejected axially from the C-trap into the fragmentation chamber 836. In Figure 8 's mass spectrometer 800, the fragmentation chamber 836 is a high energy collision dissociation (HCD) device to which collision gas is supplied. The precursor ions that reach the fragmentation chamber collide with the collision gas molecules, causing the precursor ions to fragment into fragment ions.

[0103] Although an HCD fragmentation chamber 836 is shown in Figure 8 , other fragmentation devices employing such methods as collision induced dissociation (CID), electron capture dissociation (ECD), electron transfer dissociation (ETD), photodissociation, etc. may alternatively be used. In addition, ion fragmentation can be performed in the high voltage region of the extraction trap 14.

[0104] Fragmented ions can be ejected from the fragmentation chamber 836 at the relative axial end portions into the C-trap 834. The ejected fragmented ions enter the second transfer multipole 838, i.e., a multipole ion guide. The second transfer multipole 838 guides the fragmented ions from the fragmentation chamber 836 into the extraction trap (second ion trap) 848. The extraction trap 848 is a radio-frequency voltage-controlled trap containing a buffer gas. For example, a suitable buffer gas is argon within a pressure range of 5×10 -4 mbar to 1×10 -2 mbar. The extraction trap is capable of quickly cutting off the applied RF voltage and applying a DC voltage to extract the trapped ions. A suitable planar extraction trap, also known as a rectangular ion trap, is further described in US 9,548,195, which is incorporated herein by reference. Alternatively, the C-trap is also suitable for use as the second ion trap.

[0105] An extraction trap 838 is provided to form a packet of fragmented ions before injecting the fragmented ions into the time-of-flight mass analyzer 844. The extraction trap accumulates the fragmented ions before injecting the fragmented ions into the time-of-flight mass analyzer 844, where the time-of-flight mass analyzer 844 can be a multi-reflection time-of-flight mass analyzer (MR-ToF) as described in US10699888B2. As described in US10699888B2, the MR-ToF includes a detector 848, a deflector 846, a correction bar electrode 845, an extraction trap 840, and an inclined ion mirror 842. MS1 and MS2 scans can be performed by the MR-ToF 844 or the orbitrap mass analyzer 850.

[0106] All aspects and / or features disclosed in this specification can be combined in any combination, except for combinations of at least some of such features and / or steps that are mutually exclusive. Specifically, the preferred features of the present disclosure apply to all aspects and embodiments of the present disclosure and can be used in any combination. Similarly, features described in non-essential combinations can be used alone (not in combination).

[0107] The examples herein illustrate the surface of a 1D array having elongated RF electrodes. The electrodes can also be divided into a 2D array such that each RF electrode is surrounded by electrodes of opposite polarity.

[0108] The methods and devices of the present disclosure can utilize various electrode structures. Electrodes of appropriate size can be arranged in a symmetric or asymmetric pattern on a substrate, and the electrodes can be linear or curved if elongation of the electrodes is beneficial for a particular application. Individual electrodes can be planar, hemispherical, rectangular, or other shapes. The electrodes can be PCB printed electrodes.

[0109] Although the ion guiding systems 200, 300, 400, 500 are described as having a height (or depth) in the y direction, a length in the z direction, and a width in the x direction, it should be understood that the x-axis, y-axis, and z-axis can be defined otherwise. For example, without departing from the present disclosure, an ion guiding system that is rotated relative to the ion guiding systems 200, 300, 400, 500 shown in the drawings can be provided.

[0110] In addition, it should be understood that the x-axis, y-axis, and z-axis are exemplary. For example, the "height" of the ion guiding system can be along the x-axis or z-axis defined in the figure. Similarly, the "width" of the ion guiding system (defined herein in the x direction) can be defined along the z-axis or y-axis, and the "length" of the ion guiding system (the distance between the multipole electrode and the RF surface electrode) can be defined along the x-axis or y-axis.

[0111] Although Figure 2A 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6A illustrates a plurality of electrodes extending in the z direction, it should be understood that the electrodes can extend in other directions (e.g., to change the direction of the guiding force applied by the RF electrodes).

[0112] It should be understood that there is an implicit "about" before the temperature, concentration, time, pressure, flow rate, cross-sectional area, voltage, current, etc. discussed in the present teachings, such that there are slight and non-substantial deviations within the scope of the present teachings. In addition, values referred to as "equal" can actually differ by less than a threshold amount. For example, the threshold amount can be 5%. The threshold can also be greater than 5% (e.g., 10%, 20%, or 50%) or less than 5% (e.g., 2% or 1%).

[0113] As used herein, including in the claims, unless the context otherwise indicates, the singular form of the terms herein shall be construed to include the plural form, and vice versa. By way of example, unless the context otherwise indicates, a singular reference herein included in the claims, such as "a" (such as, an electrode) means "one or more" (e.g., one or more electrodes).

[0114] In the specification and claims of the present disclosure, the words "comprising", "including", "having", and "containing" and variations of these words, e.g., "comprising" or like words mean "including but not limited to", and are not intended to (and do not) exclude other components. In addition, the use of "or" is inclusive, such that the phrase "A or B" is true when "A" is true, "B" is true, or both "A" and "B" are true.

[0115] The use of any and all examples or exemplary language provided herein ("for example," "such as," "e.g.," and similar language) is intended only to better illustrate the present disclosure and does not indicate a limitation on the scope of the present disclosure unless otherwise required. No language in this specification should be construed as indicating any non-required element essential to the practice of the present disclosure.

[0116] The terms "first" and "second" may be reversed without changing the scope of the invention. That is, an element referred to as the "first" element may be changed to be referred to as the "second" element, and an element referred to as the "second" element may be changed to be regarded as the "first" element.

[0117] Unless otherwise specified or the context otherwise requires, any steps described in this specification may be performed in any order or simultaneously. Further, where steps are described as being performed after a step, this does not exclude intervening steps being performed.

[0118] It should also be understood that, unless otherwise implicitly or explicitly understood or stated, for any given component or implementation described herein, any possible candidates or alternatives listed for that component may generally be used individually or in combination with each other. It should be understood that any such list of candidates or alternatives is merely illustrative and not restrictive unless otherwise implicitly or explicitly understood or stated.

[0119] In the detailed description of the various embodiments, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the disclosed embodiments. However, those skilled in the art will understand that these various embodiments may be practiced with or without these specific details. Additionally, those skilled in the art can readily understand that the particular order in which methods are presented and performed is illustrative, and that the order can be changed and still remain within the scope of the various embodiments disclosed herein.

[0120] Unless otherwise indicated, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the various embodiments described herein belong.

Claims

1. An ion guide, comprising: An inlet configured to allow ions to enter the ion guide, wherein the ions allowed to enter are guided along a first axis; A confinement device comprising an array of radio frequency (RF) electrodes formed along a first surface and configured to provide an RF field for confining the ions allowed to enter; And A first direct current (DC) electrode configured to receive a DC potential and thereby provide a force on the ions allowed to enter, the force having a component along a second axis perpendicular to the first axis, the first DC electrode having a surface inclined with respect to the first axis and the second axis.

2. The ion guide according to any one of the preceding claims, wherein the first DC electrode has a triangular cross-section.

3. The ion guide according to any one of the preceding claims, wherein the first DC electrode extends in the same plane as the RF electrode array.

4. The ion guide according to any one of the preceding claims, wherein a second RF surface or a counter electrode is located at a second surface of the confinement device, the second surface being arranged opposite the first surface.

5. The ion guide according to claim 4, wherein the first DC electrode is located between the first surface and the second surface.

6. The ion guide according to claim 4 or 5, wherein the first DC electrode is configured such that it does not make direct contact with the first surface or the second surface.

7. The ion guide according to any one of the preceding claims, wherein the first DC electrode is one of a plurality of DC electrodes, each of the plurality of DC electrodes extending in the same plane.

8. The ion guide according to any one of the preceding claims, wherein the first DC electrode is located at the periphery of the first surface and / or the second surface.

9. The ion guide according to any one of the preceding claims, further comprising one or more DC protection electrodes located between the first surface and the second surface or in the same plane as the first surface or the second surface, wherein the one or more DC protection electrodes are configured to provide an additional force on the ions allowed to enter.

10. The ion guide according to any one of the preceding claims, further comprising a first DC protection electrode, wherein the first DC protection electrode and the first DC electrode are configured such that the force provided on the ions allowed to enter can be controlled to be in a first direction along the first axis or in a second direction along the first axis.

11. The ion guide according to claim 10, further comprising a second DC electrode and a second DC protection electrode, wherein the first DC electrode is located on a different side of the ion path from the second DC electrode, and wherein the first DC protection electrode is located on a different side of the ion path from the second DC protection electrode.

12. The ion guide according to any one of the preceding claims, wherein the first DC electrode is an upper DC electrode, and the ion guide further comprises a lower DC electrode, and wherein the upper DC electrode and the lower DC electrode are configured such that the force exerted on the ions allowed to enter can be controlled to be in a first direction along the first axis or in a second direction along the first axis.

13. The ion guide according to claim 12, wherein the upper DC electrode is one of a pair of upper DC electrodes, and the lower DC electrode is one of a pair of lower DC electrodes, wherein one electrode of the pair of upper DC electrodes is located on a different side of the ion path from the other electrode of the pair of upper DC electrodes, and wherein one electrode of the pair of lower DC electrodes is located on a different side of the ion path from the other electrode of the pair of lower DC electrodes.

14. The ion guide according to any one of the preceding claims, wherein the ion guide further comprises an outlet through which ions are extracted.

15. The ion guide according to claim 14, wherein the inlet and the outlet are in the same plane, and the plane is substantially parallel to the first surface.

16. The ion guide according to claim 14 or 15, wherein the outlet is offset from the inlet along the second axis.

17. The ion guide according to claim 14, 15 or 16, wherein the ion guide comprises a second DC electrode, and the outlet is located between the first DC electrode and the second DC electrode, and wherein the first DC electrode and the second DC electrode are configured such that the ions are compressed along the z-axis as they are extracted through the outlet.

18. The ion guide according to any one of claims 14 to 17, wherein the first DC electrode is one of a plurality of DC electrodes, wherein each electrode of the plurality of electrodes is separated from the other electrodes of the plurality of electrodes along the first axis, and wherein each electrode of the plurality of electrodes has a surface inclined with respect to the first axis and the second axis, and wherein one or more of the plurality of electrodes are arranged such that the ions are pushed in a first direction along the first axis, and wherein one or more of the plurality of electrodes are arranged such that the ions are pushed in a second direction along the first axis, such that the ion guide is configured to cause the ions to follow a curved and / or angled path between the inlet and the outlet.

19. The ion guide according to any one of claims 14 to 18, wherein the ion guide is configured to cause the ions to follow a meandering ion path between the inlet and the outlet.

20. The ion guide according to any one of the preceding claims, wherein the inlet is configured such that ions are allowed to enter the ion guide along the first axis, or wherein the inlet is configured such that ions are allowed to enter the ion guide in a direction different from the first axis.

21. The ion guide according to any one of the preceding claims, wherein the RF electrode array forms an RF surface.

22. A beam switching device comprising the ion guide according to any one of the preceding claims.

23. An ion mobility separator comprising the ion guide according to any one of claims 1 to 21.

24. An analytical instrument comprising any one or more of the following: the ion guide according to any one of claims 1 to 21, the beam switching device according to claim 22, and / or the ion mobility separator according to claim 23.

25. The analytical instrument according to claim 24, wherein the analytical instrument is a mass spectrometer or an ion mobility spectrometer.

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