Embodiments of this disclosure are related generally to generating increased fluxes of molecular ions, and in particular embodiments are related to lenses for merging ion beams.
Mass spectrometry is an analytical technique for molecular analysis and can be used as a preparative tool for deposition of ionic species with well-defined compositions and charge states onto solid and liquid interfaces. For example, intact polyatomic ions can be mass-selected in a mass spectrometer and deposited onto a target surface with kinetic energy in the hyperthermal range (1-100 eV) or higher (100-10,000 eV). In the hyperthermal range, the relatively low kinetic energy of the ions can result in a gentle deposition of ions onto the target surface, which is referred to as ion soft landing. Current ion beam deposition techniques including ion implantation, ion beam sputter deposition, and ion beam assisted deposition typically use ion kinetic energies in the keV (kilo-electron volt) range. Ion soft landing techniques, however, use hyperthermal beams of mass-selected ions to deposit intact polyatomic ions onto surfaces. A need for generating high fluxes of hyperthermal ions for soft landing applications has been identified, and one of the stages in the process of generating high fluxes of ions may involve merging several ion beams. However, it was realized by the inventors of the present disclosure that problems still exist with merging multiple ion beams, including low energy ion beams such as those with hyperthermal energy ranges. Certain preferred features of the present disclosure address these and other needs and provide other important advantages.
Despite improvements in the ability to merge ion beams, the inventors of the present disclosure have realized that difficulties still exist. For example, while high energy ion beams (such as those with kinetic energies in the MeV (mega-electron volt) range) are relatively easy to manipulate and focus, lower energy ion beams (such as those with kinetic energies in the hyperthermal range) are more difficult to manipulate and focus. As another example, various systems cannot be used for merging ion beams of the same polarity, especially those with kinetic energies below 1 MeV, such as with merging multiple hyperthermal ion beams of the same polarity to generate a high-flux single ion beam for applications in preparative and analytical mass spectrometry.
Although ion soft landing can be complementary to other techniques such as molecular beam epitaxy and electrospray deposition, the inventors have realized that ion soft landing can provide access to a much broader range of molecules and precise control over their composition, kinetic energy, and deposition pattern on a surface. However, ion fluxes obtained using existing ion soft landing instruments are substantially lower than neutral molecule fluxes used in molecular beam epitaxy and related approaches, which limits the range of applications utilizing ion soft landing as a preparative technique. The inventors of the present disclosure realized that growing demands from both the fundamental and applied research fields can be met by scaling up of the ion soft landing instrumentation to generate substantially higher fluxes of mass-selected ions.
The inventors of the present disclosure also realized that it is still difficult to further improve ion fluxes due to the space charge limitations of current devices and methods. However, they also realized that merging of multiple ion beams could be useful in generating high fluxes of polyatomic ions, which would benefit both ion soft landing and analytical mass spectrometry. However, merging multiple hyperthermal ion beams approaching the instrument axis from different directions is difficult in that the ion trajectories must be carefully controlled to ensure the Apparatuses and Methods for Merging Ion Beams formation of a well-collimated single ion beam directed along the instrument axis while minimizing ion loss due to defocusing. The multichannel ion lens described herein provides a solution to this challenge and can increase the flux of ion beams generated from an ion source.
Embodiments of the present disclosure provide improved ion beam merging apparatuses and methods, and particular embodiments provide multichannel lenses, including multichannel ellipsoidal lenses, for merging multiple hyperthermal ion beams.
This summary is provided to introduce a selection of the concepts that are described in further detail in the detailed description and drawings contained herein. This summary is not intended to identify any primary or essential features of the claimed subject matter. Some or all of the described features may be present in the corresponding independent or dependent claims, but should not be construed to be a limitation unless expressly recited in a particular claim. Each embodiment described herein does not necessarily address every object described herein, and each embodiment does not necessarily include each feature described. Other forms, embodiments, objects, advantages, benefits, features, and aspects of the present disclosure will become apparent to one of skill in the art from the detailed description and drawings contained herein. Moreover, the various apparatuses and methods described in this summary section, as well as elsewhere in this application, can be expressed as a large number of different combinations and subcombinations. All such useful, novel, and inventive combinations and subcombinations are contemplated herein, it being recognized that the explicit expression of each of these combinations is unnecessary.
Some of the figures shown herein may include dimensions or may have been created from scaled drawings. However, such dimensions, or the relative scaling within a figure, are by way of example, and not to be construed as limiting.
For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to one or more embodiments, which may or may not be illustrated in the drawings, and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended; any alterations and further modifications of the described or illustrated embodiments, and any further applications of the principles of the disclosure as illustrated herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. At least one embodiment of the disclosure is shown in great detail, although it will be apparent to those skilled in the relevant art that some features or some combinations of features may not be shown for the sake of clarity.
Any reference to “invention” within this document is a reference to an embodiment of a family of inventions, with no single embodiment including features that are necessarily included in all embodiments, unless otherwise stated. Furthermore, although there may be references to benefits or advantages provided by some embodiments, other embodiments may not include those same benefits or advantages, or may include different benefits or advantages. Any benefits or advantages described herein are not to be construed as limiting to any of the claims.
Likewise, there may be discussion with regards to “objects” associated with some embodiments of the present invention, it is understood that yet other embodiments may not be associated with those same objects, or may include yet different objects. Any advantages, objects, or similar words used herein are not to be construed as limiting to any of the claims. The usage of words indicating preference, such as “preferably,” refers to features and aspects that are present in at least one embodiment, but which are optional for some embodiments.
Specific quantities (spatial dimensions, temperatures, pressures, times, force, resistance, current, voltage, concentrations, wavelengths, frequencies, energy, heat transfer coefficients, dimensionless parameters, etc.) may be used explicitly or implicitly herein, such specific quantities are presented as examples only and are approximate values unless otherwise indicated. Discussions pertaining to specific compositions of matter, if present, are presented as examples only and do not limit the applicability of other compositions of matter, especially other compositions of matter with similar properties, unless otherwise indicated.
Depicted in
The shapes of the electrodes 110 and passageways 120 are selected to work in concert to merge the separate ion beams together into a single beam at the exit 122 of the lens device 100. In the embodiment depicted in
Each electrode 110 includes thirteen (13) passageways 120. When the plurality of electrodes 110 are positioned in relation to one another as depicted and described, the passageways 120 align to form thirteen (13) parabolic passageways through the electrodes 110. Five (5) passageways are depicted in the sectional views of
The ellipsoids depicted in
In at least one embodiment the lens device 100 is operated using two DC (direct current) voltages, one voltage being steadily applied to even numbered electrodes 110 and the other voltage being steadily applied to odd numbered electrodes 110, resulting in adjacent electrodes 110 being at different potentials. In some embodiments, one of the applied voltages is a “ground” voltage. In addition to embodiments where alternating electrodes have the same potential (for example, electrodes in a +−+− voltage configuration), other embodiments can have alternating groupings (for example, pairs) of electrodes at the same potential (for example, electrodes in a ++−−++−− configuration). In some embodiments, each ellipsoidal electrode is controlled individually with a particular DC voltage to optimize ion transmission and focusing, with some embodiments employing a unique potential on each electrode 110.
In some embodiments alternating DC voltages are applied to the electrodes 110 to confine the ion beams in the passageways 120, such as by applying an independent DC voltage to each electrode. One advantage of this approach is overall simplicity. The alternating DC voltages can take the form of, for example, square waves, sine waves or triangular waves.
In some embodiments radio frequency (RF) voltages are applied to confine the ion beams in the passageways 120. In some embodiments, a DC gradient is applied on top of the alternating DC voltage or the RF voltage. These embodiments will guide ions to move forward even when they have low kinetic energy.
By applying particular voltages to the electrodes 110, a well-defined electrical field for efficient ion transmission can be obtained.
A downstream lens may be used for further focusing and/or collimating the combined ion beam. One example downstream lens is an einzel lens 130 (see
The multichannel lens 100 is typically constructed using a conductive material, such as stainless steel. While the aspect ratio of the ellipse formed by each electrode 110 can be varied depending on the specific implementation of each lens embodiment, an aspect ratio of approximately 0.707 is expected to produce optimal results. The angular displacement of each ion beam entering the lens from the central, horizontal axis of the device will typically be within the range 0 to 60 degrees)(0°-60°. Some embodiments include ion beams entering the lens at angular displacements higher than 60 degrees, and potentially as high as 90 degrees, although difficulties can arise when bending ion beams at these higher angular displacements. It can be seen in the 3-D shape of lens 100 depicted in
The features of the multichannel lens result in the initial velocity vectors of the multiple ion beams, and in particular those with kinetic energy of approximately 10 to 100 eV and a mass-to-charge ratio (m/z) of approximately 50 to 2,000, gradually changing and aligning along the instrument axis. Embodiments of this disclosure focus beams of ions with individual ion masses from 0.0005 to 1×109 Dalton, which include ion beams with constituent components from electrons to large biomolecules.
During operation, multiple ion beams (for example, ion beams 135, 136, 137, 138 and 139) enter the lens from different locations, entering their individual passageways through passageway entrance openings (for example, openings 140, 141, 142, 143 and 144, respectively), traveling along their individual parabolic trajectories, merging at the exit 122 of the multichannel lens 100 with the primary component of the ion velocity for each beam being directed along the horizontal instrument axis, and forming the merged ion beam 145. Ion beams also enter passageway entrance openings 146, 147, 148 and 149 and the four (4) openings that are not depicted in the figures. The merged ion beam is further focused by the downstream lens, for example einzel lens 130, and exit as indicated by an arrow. In at least one embodiment, the electrodes 110 are charged to specific voltages as described previously, typically in the range of 0 to 1,000 Volts DC, forming well-defined equipotential lines 150 as depicted in
Embodiments include lenses 100 where the spacing between the electrodes 110, the shape of the passageways 120, and the width of the passageways 120 result in the central axis of each passageway 120 being perpendicular to each individual electrode 110 (or having an incident angle of at most 10 degrees (10°) from perpendicular to each individual electrode 110), which will result in the ion pathways being perpendicular to each individual electrode 110 (or having an indecent angle of at most 10 degrees (10°) from perpendicular to each individual electrode 110) as the ions travel down each passageway 120.
Lens 100 can focus ion beams with kinetic energy ranges (kinetic energy of the individual ions in the ion beams) from 0.1 to 1×105 eV. In operation, the lens 100 can be operated in a vacuum, which can minimize collisions with neutral molecules, facilitate operation of downstream devices (for example, quadrupole mass filters), and facilitate application of higher voltages to the electrodes 110. Operating lens 100 at lower pressures also increases the breakdown voltage (the voltage at which the region between the electrodes begins to conduct electricity) allowing application of higher voltages to electrodes 110. Some embodiments operate the lens 100 in substantial vacuum (for example, pressure less than less than 1 mTorr (<0.001 Torr)) to focus ion beams, while some embodiments operate the lens 100 in a high vacuum (for example, pressure less than less than 0.00001 Torr (<1×10−5 Torr)) to focus ion beams. At these low pressures individual ions in the beam(s) can have kinetic energy of approximately 103 to 105 eV.
In use, lens device 100 may be used as part of a mass spectrometry system, with embodiments of this present disclosure having use in both preparative and analytical mass spectrometry.
The example embodiment depicted in
A good balance in the number of passageways 120 is achieved in embodiments utilizing 13 passageways 120—one central passageway with 12 passageways 120 surrounding the central passageway, six (6) of the passageways 120 being a first distance from the central passageway (one every 60 degrees surrounding the central passageway) and the remaining six (6) of the passageways 120 being at a second distance from the central passageway that is different from the first distance (one every 60 degrees surrounding the central passageway, which may be at the same rotational locations as the first-distance set of passageways 120 or located rotationally between the first-distance set of passageways). See,
Factors affecting the number of passageways include the space needed to position the ion beam generators around lens 100. Typical embodiments include from 2 to 65 passageways 120 located in the three dimensional space of the electrode stack, each with different orientations merging 2 to 65 ion beams, one ion beam in each passageway 120. Particular embodiments include from 5 to 32 passageways 120 located in the three dimensional space of the electrode stack with different orientations merging 5 to 32 ion beams, one ion beam in each passageway 120. Still further embodiments include 13 passageways 120 located in the three dimensional space of the electrode stack with different orientations merging 13 ion beams, one ion beam in each passageway 120.
The arrangement of passageways 120 can be varied depending on the number of ion beams being merged. For example, one or more passageways 120 can be located at a particular angular displacement from a central passageway, and one or more passageways can optionally be located at another angular displacement from a central passageway. In the example depicted in
Lens 100 can be sized for various applications. Embodiments of lens 100 are sized from 8 cm3 (2×2×2 cm) to 8,000,000 cm3 (200×200×200 cm). Further embodiments of lens 100 are sized from 1,000 cm3 (10×10×10 cm) to 1,000,000 cm3 (100×100×100 cm), and still further embodiments of lens 100 are sized at approximately 125,000 cm3 (50×50×50 cm).
Embodiments of lens 100 are sized with lengths (item “b” in
Further embodiments of lens 100 are sized with lengths (item “b” in
The electrode thickness to aperture diameter ratio in many embodiments, including those described above, is between one-half (0.5) and two (2), and in certain embodiments the electrode thickness to aperture diameter ratio is approximately one (1). The cross-sectional area of the ellipsoid in many embodiments, including those described above, is approximately circular with items “a” and “b” in
Although passageways 120 are described as being parabolic in shape from the outer electrode 110 to the inner electrode 110, other embodiments include passageways that are defined by differently curved shapes, for example, hyperbolic, ellipsoidal, exponential (described by an exponential function), logarithmic (described by a logarithm function), trigonometric (described by a trigonometric function), semi-cubical parabolic, serpentine (described by a serpentine curve), trident (described by a trident curve), linear segments, or piecewise functions of these shapes.
Although electrodes 110 are described as being ellipsoidal in shape, other embodiments include electrodes that are described by differently curved shapes, for example, one of or a combination of the following three-dimensional (3-D) shapes: paraboloid, hyperboloid, exponential, logarithmic, trigonometric (trigonometric functions), semi-cubical paraboloids, serpentine (described by serpentine curves), trident (described by trident curves), piecewise curves (multiple pieces of curves positioned end-to-end), and piecewise linear curves (multiple straight lines positioned end-to-end). It should be understood that the 3-D shapes described using two-dimensional (2-D) terminology refer to 3-D shapes formed by revolution, sweep, extrusion or other means of using the 2-D shape to form a 3-D shape. The shapes are chosen or combined so that the ion passageways are perpendicular to each individual electrode or have a small incident angle of no more than ten (10) degrees, and no more than twenty (20) degrees in some embodiments.
Embodiments of lenses 100 may be manufactured by subtractive or additive machining.
Depicted in
Embodiments of the ion lens can increase the total flux of ion beams generated from an ion source and produce ion beams with fluxes larger than the maximum flux achievable by an ion beam generator of a particular type. In at least some embodiments, the flux/current is improved by a factor equal to approximately the number of channels in the lens. For example, an ion lens focusing and merging 13 ion beams, each beam being generated from similar ion sources producing an ion beam with as high a flux as the source is capable, will produce a resultant ion beam with a total flux equal approximately 13 times the flux of a single ion beam. If using electrospray ion sources, each with a maximum flux of approximately 15 nA (nanoamperes), the lens can combine the ion beams from, for example, 13 electrospray ion sources and produce an ion beam with a total flux of approximately 0.5 μA (microamperes) to 1.0 μA (microamperes) by just using the ion lens.
While the embodiments illustrated in the figures depict electrodes 110 as being curved plates of unitary construction with apertures defining the passageways 120, other embodiments include electrodes 110 that are constructed of multiple components (such as electrodes constructed of smaller portions connected to one another that may, or may not, have gaps between the smaller portions) and electrodes 110 that may have additional apertures that are not used as ion beam passageways, such as perforated or mesh plates.
Elements depicted in
The following is a list of element numbers and at least one noun used to describe that element. It is understood that none of the embodiments disclosed herein are limited to these descriptions, and these element numbers can further include other words that would be understood by a person of ordinary skill reading and reviewing this disclosure in its entirety.
Reference systems that may be used herein can refer generally to various directions (for example, upper, lower, forward and rearward), which are merely offered to assist the reader in understanding the various embodiments of the disclosure and are not to be interpreted as limiting. Other reference systems may be used to describe various embodiments, such as referring to the direction of projectile movement as it exits the firearm as being up, down, rearward or any other direction.
While examples, one or more representative embodiments and specific forms of the disclosure have been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive or limiting. The description of particular features in one embodiment does not imply that those particular features are necessarily limited to that one embodiment. Some or all of the features of one embodiment can be used in combination with some or all of the features of other embodiments as would be understood by one of ordinary skill in the art, whether or not explicitly described as such. One or more exemplary embodiments have been shown and described, and all changes and modifications that come within the spirit of the disclosure are desired to be protected.
This application claims the benefit of U.S. Provisional Application No. 62/862,837, filed Jun. 18, 2019, the entirety of which is hereby incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/US2020/038525 | 6/18/2020 | WO |
Number | Date | Country | |
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62862837 | Jun 2019 | US |