Manipulation of gaseous ion beams with acoustic fields

Abstract

An apparatus for manipulation of a gaseous ion beam advantageously uses an ultrasonic acoustic field rather than physical structures, which can become contaminated or electromagnetic fields, which require high field strengths. Such apparatuses comprise an ion source having an outlet configured to release the gaseous ion beam at a flow rate along a first path; a transducer configured to generate an acoustic field along a second path that intersects or overlaps with the first path; and an ion detector. Aspects of the disclosure also provide methods of using the same to deflect, gate, focus, and separate gaseous ion beams.

Description

MANIPULATION OF GASEOUS ION BEAMS WITH ACOUSTIC FIELDSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 525,416, filed July 7, 2023, and U.S. Provisional Patent Application No. 63 / 668,468, filed July 8, 2024, which are incorporated by reference as if disclosed herein in their entirety.BACKGROUND

[0002] Approaches to control the motion and direction of ionized particles and molecules have been pursued for more than three centuries. Measuring the responses of gaseous charged species within a controlled external forcefield led to the development of mass spectrometry (MS) and ion mobility spectrometry (IMS) which have become cornerstones in contemporary chemical analyses. The ability to produce intact gaseous ions for these techniques is often performed at atmospheric-pressure (AP) due ease of sample introduction, high ionization efficiencies, and minimal fragmentation. However, diffusion and electrostatic repulsion between ions hinders the transport of gaseous ions into the lower-pressure environment of the IMS or MS. Conventional ion optics, that use electric or magnetic fields, can guide ions at AP, but require high field strengths to overcome the dominating aerodynamic effects.

[0003] Ion-based spectrometries are a resource for accurate and sensitive chemical analysis. Techniques such as mass spectrometry (MS) and ion mobility spectrometry (IMS) have superb detection limits, and provide physical data such as structure or elemental composition. To reach these low detection limits, however, it is necessary to maximize the throughput of gaseous ions from the source to the detector. Efficient transfer of ions is accomplished with electric- and magnetic-field-based devices, called ion optics. Analogous to light optics, these components are used to focus, deflect, separate, and guide ion beams throughout the instrument.

[0004] Ion gates, also referred to as ion shutters, are an ion optic, as they control the flow of ions. When the gate is open, ions can proceed into a designated region, and when the gate is closed, they are blocked. Pulsed ion spectrometries, such as time-of-flight (TOF) MS and drift tube (DT) IMS, rely on these gates to form discrete ion packets. The opening of the gate is timed with the application of an injection pulse, which sends ions into the analysis region. When the gate is closed, however, separation between the ion packets is achieved and newions are prevented from entering the analysis region prematurely. The formation of ion packets and controlled release of ions from the gate region ultimately impacts the sensitivity and resolution of the technique. Separation of ion packets and uniformity of injection helps to reduce peak broadening for time dispersive techniques such as TOF-MS and DT-IMS. Other instruments, such as linear ion traps (LITs) use gates in the form of endcap electrodes to ensure that ions remain in storage long enough to undergo fragmentation or other chemical processes before ejection and analysis.

[0005] Bradbury-Nielsen gates (BNGs) are commonly used in IMS instrumentation due to their ability to open and close within nanoseconds. This gate is formed from interdigitated wires (FIG. 20A) where every other wire is biased relative to a reference potential. The spacing of the wires can range from 50 pm to greater than 1 mm depending on the application. For the gate to transmit (gate is open), the wires are placed at the same potential as a reference potential. The gate is closed by re-establishing an orthogonal electric field, which will cause the ions to deviate from their initial path and not reach the detector. Interactions between the orthogonal field and drift field behind the gate lead to the formation of a depletion region, where ions that have not traveled far enough past the gate will be pulled back towards the gate and neutralized. Recent work has also shown that a depletion region exists on the ionization side of the gate, due to the penetration of the closing field of the BNG into the ionization region. Additionally, ions can collide with the wires of the gate, which neutralizes the ions on the wire surface leading to contamination and poorer sensitivity. In typical use scenarios, about 2% of the gate cross section is covered by wires, but it can increase to up to 20% when the wire spacing is decreased. Physical contact with the gate can also lead to contamination through deposition of material on the wires, and thus it is necessary to periodically clean the shutter. This type of maintenance becomes challenging, as it can disrupt the wire spacing and lead to changes in the efficacy of the shutter. Gates with smaller wire spacings (<75 pm) will be more sensitive to this, as less than 10 pm precision in the wire placement leads to inconsistent deflection of ions and a less effective gate.

[0006] The Tyndall-Powell ion gate (TPG) relies on a similar principle of pulsed electrostatic fields to deflect ions. Whereas a BNG is a single frame with wires of opposite potentials, a TPG consists of two wire grids held at opposite potentials and spaced apart by ~1 mm (FIG. 20B). The sequence of grid potentials used depends on the polarity of ions to be gated. In the case of gating positive ions, the first and second grid are set to negative and positivepotentials, respectively, when the gate is closed. To open the gate, the potentials are reversed. While TPGs are simpler to construct and easier to maintain, there are several drawbacks. The finite spacing of the meshes leads to an increased depletion region and there is more surface area for ion losses and contaminations due to the presence of a second mesh. Additionally, the comparatively thick geometry of the TPG increases the time needed for the ions to traverse the gate when open, which limits the ability to form narrow ion packets.SUMMARY

[0007] To address the above issues, some embodiments of the present technology are directed to systems that utilize low-power acoustic fields to move, shape, gate and separate beams of gaseous ions at atmospheric pressure, referred to herein as Acoustic Ion Manipulation Spectrometry (AIMS). In one embodiment of an AIMS system, a standing acoustic wave was formed with two ultrasonic speakers and placed between an ionization source and ion detector. In some embodiments, a traveling acoustic wave can be formed with one or more ultrasonic speakers and placed between an ionization source and ion detector. Ion beams preferentially travel through regions of stable pressure gradients (z.e., nodes) and deflect from unstable regions (z.e., antinodes).

[0008] Shadowgraphy revealed that the ions are separated from a neutral gas stream. In an embodiment, a standing acoustic wave was formed by aligning two ultrasonic speakers towards each other. The result is an ultrasonic standing wave with equally spaced nodes (ie., static pressure) and anti-nodes (z.e., rapidly varying pressure). When a gas-stream containing ions was pointed at an antinode of the resonator, the ions were deflected and only detected in an adjacent node.

[0009] Aspects of the present disclosure are directed to apparatuses for manipulation of a gaseous ion beam comprising: an ion source having an outlet configured to release the gaseous ion beam at a flow rate along a first path; a resonator configured to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path; and an ion detector.

[0010] In some embodiments, the ion source comprises a plasma ionization source, e.g., a flowing atmospheric pressure afterglow source. In some embodiments, the ion source comprises a direct analysis in real time (DART) source. In some embodiments, the ion source comprises an electrospray ionization (ESI) source, a nanoelectrospray ionization (nESI)source, a desorption electrospray ionization (DESI) source, and atmospheric-pressure chemical ionization (APCI) source, or an atmospheric-pressure photoionization (APPI) source.

[0011] In some embodiments, the flow rate comprises between about 0.0001 L min'1and about 0.1 L min'1, between about 0.1 L min'1and about 0.2 L min'1, between about 0.2 L min'1and about 0.3 L min'1, between about 0.3 L min'1and about 0.4 L min'1, between about 0.4 L min'1and about 0.5 L min'1, between about 0.5 L min'1and about 0.6 L min'1, between about 0.6 L min'1and about 0.7 L min'1, between about 0.7 L min'1and about 0.8 L min'1, between about 0.8 L min'1and about 0.9 L min'1, between about 0.9 L min'1and about 1.0 L min'1, between about 1.0 L min'1and about 1.1 L min'1, between about 1.1 L min'1and about 1.2 L min'1, between about 1.2 L min'1and about 1.3 L min'1, or between about 1.4 L min'1and about 1.5 L min'1.

[0012] In some embodiments, the apparatus further comprises a discharge gas inlet configured to receive a discharge gas and release it to a discharge chamber of the ion source. Suitable discharge gases comprise air, helium, neon, argon, xenon, nitrogen, oxygen, sulfur hexafluoride (SFe), and mixtures thereof. In some embodiments, the discharge gas comprises a mixture of any of these gases with oxygen and / or hydrogen, e.g., air / hydrogen, helium / hydrogen, neon / hydrogen, argon / hydrogen, xenon / hydrogen, nitrogen / hydrogen, oxygen / hydrogen, sulfur hexafluoride / hydrogen, air / oxygen, helium / oxygen, neon / oxygen, argon / oxygen, xenon / oxygen, nitrogen / hydrogen, or sulfur hexafluoride / oxygen.

[0013] In some embodiments, the resonator comprises a first transducer and a first reflector. In some embodiments, the resonator comprises a first transducer and a second transducer. In some embodiments, the apparatus further comprising a second resonator. In some embodiments, the second resonator comprises a third transducer and a second reflector. In some embodiments, the second resonator comprises a third transducer and a fourth transducer.

[0014] In some embodiments, the resonator is configured to produce a resonance frequency between about 1 kHz and about 5 kHz, between about 5 kHz and about 10 kHz, between about 10 kHz and about 15 kHz, between about 15 kHz and about 20 kHz, between about 20 kHz and about 25 kHz, between about 25 kHz and about 30 kHz, between about 30 kHz and about 35 kHz, between about 35 kHz and about 40 kHz, between about 40 kHz and about45 kHz, between about 45 kHz and about 50 kHz, between about 50 kHz and about 55 kHz, between about 55 kHz and about 60 kHz, between about 60 kHz and about 65 kHz, between about 65 kHz and about 70 kHz, between about 70 kHz and about 75 kHz, between about 75 kHz and about 80 kHz, between about 80 kHz and about 85 kHz, between about 85 kHz and about 90 kHz, between about 90 kHz and about 95 kHz, or between about 85 kHz and about 100 kHz.

[0015] In some embodiments, the ion detector comprises a mass spectrometer, an ion charge- coupled device, or a Faraday collector. In some embodiments, the ion detector comprises an inlet positioned opposite to the outlet and at least partially aligned with the first path. In some embodiments, ion detector comprises an inlet positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path by up to about 1 mm, up to about 2 mm, up to about 3 mm, up to about 4 mm, up to about 5 mm, up to about 6 mm, up to about 7 mm, up to about 8 mm, up to about 9 mm, or up to about 10 mm.

[0016] Aspects of the present disclosure are directed to methods of deflecting a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer(s) sufficient to at least partially deflect the gaseous ion beam around the antinode; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

[0017] In some embodiments, the peak voltage is between about 5 Vp.pand about 10 Vp.p, between about 10 Vp.pand about 15 Vp.p, between about 15 Vp.pand about 20 Vp.p, between about 20 Vp.p and about 25 Vp.p, between about 25 Vp.pand about 30 Vp.p, between about 30 Vp-p and about 35 Vp.p, between about 35 Vp.pand about 40 Vp.p, between about 40 Vp.pand about 45 Vp.p, between about 45 Vp.pand about 50 Vp.p, between about 50 Vp.pand about 55 Vp.p, between about 55 Vp.pand about 60 Vp.p, between about 60 Vp.pand about 65 Vp.p, between about 65 Vp.pand about 70 Vp.p, between about 70 Vp.pand about 75 Vp.p, between about 75 Vp.p and about 80 Vp.p, between about 80 Vp.pand about 85 Vp.p, between about 85 Vp.p and about 90 Vp.p, between about 90 Vp.pand about 95 Vp.p, between about 95 Vp.pand about 100 Vp.p, between about 100 Vp.pand about 105 Vp.p, between about 105 Vp.pand about 110 Vp.p, between about 110 Vp.pand about 115 Vp.p, between about 115 Vp.pand about120 Vp.p, between about 120 Vp.pand about 125 Vp.p, between about 125 Vp.pand about130 Vp.p, between about 130 Vp.pand about 135 Vp.p, between about 135 Vp.pand about140 Vp.p, between about 140 Vp.pand about 145 Vp.p, between about 145 Vp.pand about150 Vp.p, between about 150 Vp.pand about 155 Vp.p, between about 155 Vp.pand about160 Vp.p, between about 160 Vp.pand about 165 Vp.p, between about 165 Vp.pand about170 Vp.p, between about 170 Vp.pand about 175 Vp.p, between about 175 Vp.pand about180 Vp.p, between about 180 Vp.pand about 185 Vp.p, between about 185 Vp.pand about190 Vp.p, between about 190 Vp.pand about 195 Vp.p, between about 195 Vp.pand about200 Vp.p, between about 200 Vp.pand about 205 Vp.p, between about 205 Vp.pand about210 Vp.p, between about 210 Vp.pand about 215 Vp.p, between about 215 Vp.pand about220 Vp.p, between about 220 Vp.pand about 225 Vp.p, between about 225 Vp.pand about230 Vp.p, between about 230 Vp.pand about 235 Vp.p, between about 235 Vp.pand about240 Vp.p, between about 240 Vp.pand about 245 Vp.p, between about 245 Vp.pand about250 Vp.p, between about 250 Vp.pand about 255 Vp.p, between about 255 Vp.pand about260 Vp.p, between about 260 Vp.pand about 265 Vp.p, between about 265 Vp.pand about270 Vp.p, between about 270 Vp.pand about 275 Vp.p, between about 275 Vp.pand about280 Vp.p, between about 280 Vp.pand about 285 Vp.p, between about 285 Vp.pand about290 Vp.p, between about 290 Vp.pand about 295 Vp.p, or between about 295 Vp.pand about 300 Vp.p.

[0018] In some embodiments, the first path is colinear with the second path. In some embodiments, an angle between the first path and the second path is between about 0.01 degrees and about 5 degrees, between about 5 degrees and about 10 degrees, between about 10 degrees and about 15 degrees, between about 15 degrees and about 20 degrees, between about 20 degrees and about 25 degrees, between about 25 degrees and about 30 degrees, between about 30 degrees and about 35 degrees, between about 35 degrees and about 40 degrees, between about 40 degrees and about 45 degrees, between about 45 degrees and about 50 degrees, between about 50 degrees and about 55 degrees, between about 55 degrees and about 60 degrees, between about 60 degrees and about 65 degrees, between about 65 degrees and about 70 degrees, between about 70 degrees and about 75 degrees, between about 75 degrees and about 80 degrees, between about 80 degrees and about 85 degrees, between about 85 degrees and about 90 degrees, between about 90 degrees and about 95 degrees, between about 95 degrees and about 100 degrees, between about 100 degrees and about 105 degrees, between about 105 degrees and about 110 degrees, between about 110degrees and about 115 degrees, between about 115 degrees and about 120 degrees, between about 120 degrees and about 125 degrees, between about 125 degrees and about 130 degrees, between about 130 degrees and about 135 degrees, between about 135 degrees and about 140 degrees, between about 140 degrees and about 145 degrees, between about 145 degrees and about 150 degrees, between about 150 degrees and about 155 degrees, between about 155 degrees and about 160 degrees, between about 160 degrees and about 165 degrees, between about 165 degrees and about 170 degrees, between about 170 degrees and about 175 degrees, or between about 175 degrees and about 180 degrees. In some embodiments, the angle is about 90 degrees.

[0019] Aspects of the present disclosure are directed to methods of gating a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer(s) sufficient to block a percentage of ions from the gaseous ion beam from entering the inlet of the mass spectrometer.

[0020] In some embodiments, the percentage is between about 5% and about 10%, between about 10% and about 15%, between about 15% and about 20%, between about 20% and about 25%, between about 25% and about 30%, between about 30% and about 35%, between about 35% and about 40%, between about 40% and about 45%, between about 45% and about 50%, between about 50% and about 55%, between about 55% and about 60%, between about 60% and about 65%, between about 60% and about 70%, between about 70% and about 75%, between about 75% and about 80%, between about 80% and about 85%, between about 85% and about 90%, between about 90% and about 95%, or between about 95% and about 100%.

[0021] Aspects of the present disclosure are directed to methods of focusing a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a first resonator to generate a first node and a first antinode along a second path that intersects with the first path,wherein the node is positioned at least partially within the first path; and configuring a second resonator to generate a second node and a second antinode along a third path that intersects with the first path, wherein the second node is positioned at least partially within the first path. In some embodiments, the third path intersects the second path.

[0022] Aspects of the present disclosure are directed to methods of separating a first ion and a second ion in a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer(s) sufficient to enrich a concentration of the first ions from the gaseous ion beam that enter the inlet of the mass spectrometer; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

[0023] Aspects of the present disclosure are directed to apparatuses for manipulation of a gaseous ion beam comprising: an ion source having an outlet configured to release the gaseous ion beam at a flow rate along a first path; an acoustic field generator configured to generate a travelling acoustic wave along a second path that intersects with the first path; and an ion detector.

[0024] In some embodiments, the ion source comprises a plasma ionization source, e.g., a flowing atmospheric pressure afterglow source. In some embodiments, the ion source comprises a direct analysis in real time (DART) source. In some embodiments, the ion source comprises an electrospray ionization (ESI) source, a nanoelectrospray ionization (nESI) source, a desorption electrospray ionization (DESI) source, and atmospheric-pressure chemical ionization (APCI) source, or an atmospheric-pressure photoionization (APPI) source.

[0025] In some embodiments, the flow rate comprises between about 0.0001 L min'1and about 0.1 L min'1, between about 0.1 L min'1and about 0.2 L min'1, between about 0.2 L min'1and about 0.3 L min'1, between about 0.3 L min'1and about 0.4 L min'1, between about 0.4 L min'1and about 0.5 L min'1, between about 0.5 L min'1and about 0.6 L min'1, between about 0.6 L min'1and about 0.7 L min'1, between about 0.7 L min'1and about 0.8 L min'1, between about 0.8 L min'1and about 0.9 L min'1, between about 0.9 L min'1and about 1.0 Lmin'1, between about 1.0 L min'1and about 1.1 L min'1, between about 1.1 L min'1and about 1.2 L min'1, between about 1.2 L min'1and about 1.3 L min'1, or between about 1.4 L min'1and about 1.5 L min'1.

[0026] In some embodiments, the apparatus further comprising a discharge gas inlet configured to receive a discharge gas and release it to a discharge chamber of the ion source. Suitable discharge gases comprise air, helium, neon, argon, xenon, nitrogen, oxygen, sulfur hexafluoride (SFe), and mixtures thereof. In some embodiments, the discharge gas comprises a mixture of any of these gases with oxygen and / or hydrogen, e.g., air / hydrogen, helium / hydrogen, neon / hydrogen, argon / hydrogen, xenon / hydrogen, nitrogen / hydrogen, oxygen / hydrogen, sulfur hexafluoride / hydrogen, air / oxygen, helium / oxygen, neon / oxygen, argon / oxygen, xenon / oxygen, nitrogen / hydrogen, or sulfur hexafluoride / oxygen.

[0027] In some embodiments, the acoustic field generator comprises a first transducer and a first acoustic absorbing material. In some embodiments, the acoustic field generator comprises a first transducer and a second transducer. In some embodiments, the apparatus further comprises a second acoustic field generator. In some embodiments, the second acoustic field generator comprises a third transducer and a second acoustic absorbing material. In some embodiments, the second acoustic field generator comprises a third transducer and a fourth transducer.

[0028] In some embodiments, the acoustic field generator is configured to produce a travelling acoustic wave having a frequency between about 1 kHz and about 5 kHz, between about 5 kHz and about 10 kHz, between about 10 kHz and about 15 kHz, between about 15 kHz and about 20 kHz, between about 20 kHz and about 25 kHz, between about 25 kHz and about 30 kHz, between about 30 kHz and about 35 kHz, between about 35 kHz and about 40 kHz, between about 40 kHz and about 45 kHz, between about 45 kHz and about 50 kHz, between about 50 kHz and about 55 kHz, between about 55 kHz and about 60 kHz, between about 60 kHz and about 65 kHz, between about 65 kHz and about 70 kHz, between about 70 kHz and about 75 kHz, between about 75 kHz and about 80 kHz, between about 80 kHz and about 85 kHz, between about 85 kHz and about 90 kHz, between about 90 kHz and about 95 kHz, or between about 85 kHz and about 100 kHz.

[0029] In some embodiments, the first path is colinear with the second path. In some embodiments, an angle between the first path and the second path is between about 0.01degrees and about 5 degrees, between about 5 degrees and about 10 degrees, between about 10 degrees and about 15 degrees, between about 15 degrees and about 20 degrees, between about 20 degrees and about 25 degrees, between about 25 degrees and about 30 degrees, between about 30 degrees and about 35 degrees, between about 35 degrees and about 40 degrees, between about 40 degrees and about 45 degrees, between about 45 degrees and about 50 degrees, between about 50 degrees and about 55 degrees, between about 55 degrees and about 60 degrees, between about 60 degrees and about 65 degrees, between about 65 degrees and about 70 degrees, between about 70 degrees and about 75 degrees, between about 75 degrees and about 80 degrees, between about 80 degrees and about 85 degrees, between about 85 degrees and about 90 degrees, between about 90 degrees and about 95 degrees, between about 95 degrees and about 100 degrees, between about 100 degrees and about 105 degrees, between about 105 degrees and about 110 degrees, between about 110 degrees and about 115 degrees, between about 115 degrees and about 120 degrees, between about 120 degrees and about 125 degrees, between about 125 degrees and about 130 degrees, between about 130 degrees and about 135 degrees, between about 135 degrees and about 140 degrees, between about 140 degrees and about 145 degrees, between about 145 degrees and about 150 degrees, between about 150 degrees and about 155 degrees, between about 155 degrees and about 160 degrees, between about 160 degrees and about 165 degrees, between about 165 degrees and about 170 degrees, between about 170 degrees and about 175 degrees, or between about 175 degrees and about 180 degrees. In some embodiments, the angle is about 90 degrees.

[0030] In some embodiments, the ion detector comprises a mass spectrometer, an ion charge- coupled device, or a Faraday collector. In some embodiments, the ion detector comprises an inlet positioned opposite to the outlet and at least partially aligned with the first path. In some embodiments, the ion detector comprises an inlet positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path by up to about 1 mm, up to about 2 mm, up to about 3 mm, up to about 4 mm, up to about 5 mm, up to about 6 mm, up to about 7 mm, up to about 8 mm, up to about 9 mm, or up to about 10 mm.

[0031] Aspects of the present disclosure are directed to methods of deflecting a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an acoustic field generator to generate a travelling acoustic wave along a second path that intersects with the first path, wherein the acoustic fieldgenerator comprises a transducer and is further configured to increase a peak voltage of the transducer sufficient to at least partially deflect the gaseous ion beam from the first path; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

[0032] In some embodiments, the peak voltage is between about 5 Vp.pand about 10 Vp.p, between about 10 Vp.pand about 15 Vp.p, between about 15 Vp.pand about 20 Vp.p, between about 20 Vp.p and about 25 Vp.p, between about 25 Vp.pand about 30 Vp.p, between about 30 Vp-p and about 35 Vp.p, between about 35 Vp.pand about 40 Vp.p, between about 40 Vp.pand about 45 Vp.p, between about 45 Vp.pand about 50 Vp.p, between about 50 Vp.pand about 55 Vp.p, between about 55 Vp.pand about 60 Vp.p, between about 60 Vp.pand about 65 Vp.p, between about 65 Vp.pand about 70 Vp.p, between about 70 Vp.pand about 75 Vp.p, between about 75 Vp.p and about 80 Vp.p, between about 80 Vp.pand about 85 Vp.p, between about 85 Vp.p and about 90 Vp.p, between about 90 Vp.pand about 95 Vp.p, between about 95 Vp.pand about 100 Vp.p, between about 100 Vp.pand about 105 Vp.p, between about 105 Vp.pand about 110 Vp.p, between about 110 Vp.pand about 115 Vp.p, between about 115 Vp.pand about 120 Vp.p, between about 120 Vp.pand about 125 Vp.p, between about 125 Vp.pand about130 Vp.p, between about 130 Vp.pand about 135 Vp.p, between about 135 Vp.pand about140 Vp.p, between about 140 Vp.pand about 145 Vp.p, between about 145 Vp.pand about150 Vp.p, between about 150 Vp.pand about 155 Vp.p, between about 155 Vp.pand about160 Vp.p, between about 160 Vp.pand about 165 Vp.p, between about 165 Vp.pand about170 Vp.p, between about 170 Vp.pand about 175 Vp.p, between about 175 Vp.pand about180 Vp.p, between about 180 Vp.pand about 185 Vp.p, between about 185 Vp.pand about190 Vp.p, between about 190 Vp.pand about 195 Vp.p, between about 195 Vp.pand about200 Vp.p, between about 200 Vp.pand about 205 Vp.p, between about 205 Vp.pand about210 Vp.p, between about 210 Vp.pand about 215 Vp.p, between about 215 Vp.pand about220 Vp.p, between about 220 Vp.pand about 225 Vp.p, between about 225 Vp.pand about230 Vp.p, between about 230 Vp.pand about 235 Vp.p, between about 235 Vp.pand about240 Vp.p, between about 240 Vp.pand about 245 Vp.p, between about 245 Vp.pand about250 Vp.p, between about 250 Vp.pand about 255 Vp.p, between about 255 Vp.pand about260 Vp.p, between about 260 Vp.pand about 265 Vp.p, between about 265 Vp.pand about270 Vp.p, between about 270 Vp.pand about 275 Vp.p, between about 275 Vp.pand about280 Vp.p, between about 280 Vp.pand about 285 Vp.p, between about 285 Vp.pand about290 Vp.p, between about 290 Vp.pand about 295 Vp.p, or between about 295 Vp.pand about 300 Vp.p.

[0033] Aspects of the present disclosure are directed to methods of gating a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring an acoustic field generator to generate a travelling acoustic wave along a second path that intersects with the first path, and wherein the acoustic field generator comprises a transducer and is further configured to increase a peak voltage of the transducer sufficient to block a percentage of ions from the gaseous ion beam from entering the inlet of the mass spectrometer.

[0034] In some embodiments, the percentage is between about 5% and about 10%, between about 10% and about 15%, between about 15% and about 20%, between about 20% and about 25%, between about 25% and about 30%, between about 30% and about 35%, between about 35% and about 40%, between about 40% and about 45%, between about 45% and about 50%, between about 50% and about 55%, between about 55% and about 60%, between about 60% and about 65%, between about 60% and about 70%, between about 70% and about 75%, between about 75% and about 80%, between about 80% and about 85%, between about 85% and about 90%, between about 90% and about 95%, or between about 95% and about 100%.

[0035] Aspects of the present disclosure are directed to methods of focusing a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a first acoustic field generator to generate a first travelling acoustic wave along a second path that intersects with the first path; and configuring a second acoustic field generator to generate a second travelling acoustic wave along a third path that intersects with the first path. In some embodiments, the third path intersects the second path.

[0036] Aspects of the present disclosure are directed to methods of separating a first ion and a second ion in a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an acoustic field generator to generate a travelling acoustic wave along a second path that intersects with the first path, andwherein the acoustic field generator comprises a transducer and is further configured to increase a peak voltage of the transducer sufficient to enrich a concentration of the first ion from the gaseous ion beam that enter the inlet of the mass spectrometer; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings show embodiments of the disclosed subject matter for the purpose of illustrating the invention. However, it should be understood that the present application is not limited to the precise arrangements and instrumentalities shown in the drawings, wherein:

[0038] FIG. 1 A is a schematic representation of a system for ion beam mapping according to some embodiments of the present disclosure;

[0039] FIG. IB is a graph of measured relative sound pressure level (SPL) according to some embodiments of the present disclosure;

[0040] FIG. 1C is a graph showing the ion trajectory of C>2+at m / z 32 in the absence of the standing acoustic wave within the resonator according to some embodiments of the present disclosure;

[0041] FIG. ID is a graph showing the ion trajectory of C>2+at m / z 32 in the presence of the standing acoustic wave within the resonator according to some embodiments of the present disclosure;

[0042] FIG. 2 is side by side images obtained by direct observation, with the defocusing shadowgraphy method, of a gas stream travelling through an antinode (bright regions in panel b) within an acoustic resonator according to some embodiments of the present disclosure;

[0043] FIG. 3 A is a schematic of an acoustic-ion manipulation configuration used for ion fractionation and / or gating according to some embodiments of the present disclosure;

[0044] FIG. 3B is a graph showing ion separation through differences in attenuation with acoustic field strength, shown as ultrasonic transducer voltage according to some embodiments of the present disclosure;

[0045] FIG. 4A is a schematic of a 2D acoustic resonator array for atmospheric-pressure ion focusing according to some embodiments of the present disclosure;

[0046] FIG. 4B is a graph showing the y-z slice of the ion at m / z 37 mapped in 3D space according to some embodiments of the present disclosure;

[0047] FIG. 4C is a graph showing the center slice of the acoustic field that was determined experimentally according to some embodiments of the present disclosure;

[0048] FIG. 4D is a graph showing the ion abundances of m / z 32 and 37 at the “focal point” with and without the acoustic field according to some embodiments of the present disclosure;

[0049] FIG. 5 is a schematic showing experimental geometry in three-dimensional view (no perspective was used to render this image) according to some embodiments of the present disclosure;

[0050] FIG. 6 is a schematic of a FAPA source according to some embodiments of the present disclosure;

[0051] FIG. 7 is a graph showing a typical background mass spectrum acquired with a nitrogen-based FAPA source on the LTQ-XL mass spectrometer according to some embodiments of the present disclosure;

[0052] FIG. 8 is a schematic of an ultrasonic driver circuit according to some embodiments of the present disclosure;

[0053] FIG. 9 is a schematic of a circuit for sound pressure measurement according to some embodiments of the present disclosure;

[0054] FIG. 10A is a graph showing ion trajectories of (H2O)2‘H+at m / z 37 according to some embodiments of the present disclosure;

[0055] FIG. 10B is a graph showing ion trajectories of (H2O)2‘H+at m / z 37 without the resonance acoustic field according to some embodiments of the present disclosure;

[0056] FIG. 10C is a graph showing Ion trajectories of (H2O)2‘H+at m / z 37 with the resonance acoustic field according to some embodiments of the present disclosure;

[0057] FIG. 11 is a schematic of defocusing (DF) shadowgraphy system according to some embodiments of the present disclosure;

[0058] FIG. 12 is an averaged camera image of a resonant acoustic field, the time-dependent averaged pixel signal in the inner box, and the energy spectrum after Fourier transform of the averaged pixel signal in the outer box according to some embodiments of the present disclosure;

[0059] FIG. 13 is an illustration the real and imaginary parts of the camera image from FIG. 12 with a band-pass filter at 0.4 Hz according to some embodiments of the present disclosure;

[0060] FIG. 14 is a graph showing ion-specific response functions of water-related ions according to some embodiments of the present disclosure;

[0061] FIG. 15A is a schematic of an offset configuration according to some embodiments of the present disclosure;

[0062] FIG. 15B is a graph showing ion-specific response curves according to some embodiments of the present disclosure;

[0063] FIG. 16 is a schematic of 2D transducer-array framework according to some embodiments of the present disclosure;

[0064] FIG. 17 is a schematic of an ion focusing apparatus according to some embodiments of the present disclosure;

[0065] FIG. 18A is an isosurface that shows the region where the ion beam flowed through according to some embodiments of the present disclosure;

[0066] FIG. 18B are slices that shows the region where the ion beam flowed through according to some embodiments of the present disclosure;

[0067] FIG. 19 is a graph showing ion counts according to some embodiments of the present disclosure;

[0068] FIG. 20A is a schematic of a Bradbury Nielsen gate (the wires are of alternating potentials when the gate is closed) according to the prior art;

[0069] FIG. 20B is a schematic of a Tyndall-Powell gate (the sequencing of potentials on the two different grids varies depending on what ion polarity the gate is meant to block) according to the prior art;

[0070] FIG. 21 is a schematic of the experimental set-up, with the lonCCD as a sample detector (the lonCCD is oriented with the array along the y-axis) according to some embodiments of the present disclosure;

[0071] FIG. 22A is a graph showing changes to ion beam position in the presence of an antinode with the lonCCD array along the y-axis according to some embodiments of the present disclosure;

[0072] FIG. 22B is a graph showing no changes to ion beam position, but ion signal decrease, in the presence of an antinode with the lonCCD array along the x-axis according to some embodiments of the present disclosure;

[0073] FIG. 23 A is a graph showing a comparison of transmission through a closed gate for the lonCCD, Faraday collector and MS with the same source conditions (flow rate: 0.75 L min'1, discharge current: 3 mA, front plate bias: 50V) and acoustic field conditions (37.8 kHz, 20 Vp.p) according to some embodiments of the present disclosure;

[0074] FIG.23B is a graph showing total ion chronogram for the MS at the given source and field conditions (shaded regions indicate the gate is closed, according to some embodiments of the present disclosure;

[0075] FIG. 24 is a graph of total ion signal transmitting through the acoustic gate as a function of voltage applied to the ultrasonic transducers of ions reach the MS inlet relative to the amplitude of one of the sine waves in the standing wave (source conditions were a flow rate of 0.5 L min'1and a discharge current of 15 mA) according to some embodiments of the present disclosure;

[0076] FIG. 25A is a graph showing the transmission through an antinode based on potential difference between the source and MS inlet (the source was operated with a helium flow rate of 0.75 L min'1, and a discharge current of 10 mA) according to some embodiments of the present disclosure;

[0077] FIG. 25B is a graph showing the transmission of ions through an antinode into a mass spectrometer depends on the linear velocity of the ion beam (in L min'1, the flow rates are 0.25, 0.5, 0.75 and 1.0 L min'1; the source was run with a discharge current of 15 mA) according to some embodiments of the present disclosure;

[0078] FIG. 26 is a graph of the total ion current at optimized conditions (flow rate: 0.5 LPM, discharge current: 15 mA, 0V applied bias) with one ion gate (shaded regions indicate the gate is closed) according to some embodiments of the present disclosure;

[0079] FIG. 27A is a graph showing the total ion current of single and dual ion gating (the symbol “1G” indicates one gate is present in the ion beam path, while “2G” indicates two gates are present; the source conditions were a flow rate of 0.5 L min'1and a discharge current of 15 mA) according to some embodiments of the present disclosure;

[0080] FIG. 27B is a graph of the average ion signals are given for when zero, one or two acoustic gates are present in the ion beam path according to some embodiments of the present disclosure according to some embodiments of the present disclosure; and

[0081] FIG. 28 is a graph of a comparison of the total ion chronogram and extracted ion chronogram for aniline (m / z 94.07), where shaded regions indicate the gate is closed according to some embodiments of the present disclosure.DETAILED DESCRIPTION

[0082] Because ionized particles and molecules are charged, nearly all approaches to control the motion and direction of these species utilize strong electromagnetic forces to align or orient dipoles of the ions within the surrounding potential gradients; the electrostatic and / or Lorentz forces come from external electric fields and magnetic fields, respectively. The ability to carefully control and then measure the responses of charged species within an external forcefield has led to a myriad of instrumental and technological developments towards analytical and industrial applications. The presence of a well-defined forcefield can cause predictable spatial and temporal dispersions of different ionic species, resulting in the information on ion identities that can be translated to useful chemical information. Based on these discoveries, methods such as electrophoresis, ion chromatography, mass spectrometry (MS) and ion mobility spectrometry (IMS) have become cornerstones in contemporary sample purification and chemical analyses.

[0083] While targeted guiding of ions, such as defining ion trajectories and trapping, in controlled environments (e.g., vacuum and controlled gas environment) are well established, many attempts have been made to achieve similar performances under ambient conditions. In comparison with low-pressure (e.g., high vacuum) conditions, the high collisional frequencies at atmospheric conditions can dampen the coulombic forces and, ultimately, require higher field strengths to manipulate ( / . e. , focus, transport, guide, and gate) ions at elevated pressure. For instance, voltages ranging from a few to several -tens of kilovolts are commonly used to overcome the dominating aerodynamic effects. The consequences of frequent collisions between a target molecule and the surrounding gas species can be detrimental to electric- and magnetic-field manipulation methods and even optical methods. Since coulombic interactions are being dominated by collision-induced behavior when moving towards higher densities / pressures, shifting the paradigm to exploiting the charge dependent collision behavior appears to be the preferrable route. The collision-controlled dynamics in continuous media thus far is most commonly used in chromatography and IMS applications, in which a mere retardation according to the interaction cross section is achieved. However, methods that exploit bulk medium interactions ( / . e. , acoustics) to enable controlled trajectories of a travelling ensemble certainly exist and have been gaining increased attention in recent years. This specific class of methods are commonly referred to as acoustic levitation and acoustic tweezers. These use a rapidly alternating acoustic pressure gradient that effectively reaches a balance and exhibits static properties. The result is that a target object can be moved and controlled on a much larger time scale e.g., seconds to minutes) compared to that of a periodic acoustic field (e.g., micro- to milliseconds).

[0084] Non-contact object handling and spatial confinement of objects enabled discoveries in many fields. Certainly, the convenience and potential to avoid surfaces draw attentions from a perspective that aims at chemical identification, especially along the concept of direct mass- spectrometric analyses. More specifically, the concept of ambient desorption / ionization mass spectrometry (ADI-MS) led to the development of plasma-based ionization sources for MS that utilize reagent ions produced by an electrical discharge for highly efficient chemical detection and quantification; examples include direct analysis in real-time (DART), flowing atmospheric-pressure afterglow (FAP A) and low-temperature plasma (LTP) probe. While both acoustic object handling and ADI methods are simple, the combination of these two has not been proposed. Conceptually, analytes in condensed phase samples held within an acoustic levitator could be desorbed and ionized by an ADI source, and transported to a massspectrometer for detection and identification. However, during attempts to do this with a analyte-containing levitated droplet, no analyte signal from species within the droplet was detected. Surprisingly, ions that were produced by the source and carried by the thin gas stream (e.g., -2 mm diameter at 3-5 m / s linear velocity) did not reach the ion detector at all with the presence of an acoustic levitator as the droplet sample holder. Without wishing to be bound by theory, the presence of a resonant acoustic field might have blocked the ion beam from entering the atmospheric-pressure inlet of the mass spectrometer. In other words, the ion trajectory was unexpectedly altered by the acoustic force field, even if the ions were carried and shielded by a neutral stream of gas.

[0085] Again without wishing to be bound by theory, because it is improbable that the source-produced ions were fully consumed or neutralized by travelling through a resonant acoustic field in the open air, the spatial distribution of ions measured by MS and the acoustic pressure field were mapped in two dimensional space (FIG. 1 A, Example 1). To rule out possible medium interactions, nitrogen was used as discharge gas instead of commonly used helium, where the speed-of-sound of helium is nearly three-times of that of air. In some embodiments, a low nitrogen flow rate (0.85 L min'1) a long cylindrical exit tube from the source ensured a laminar flow for species exiting the ion source. In some embodiments, a corona discharge sustained at 5 kV, which required -0.67 pA of current, was chosen so the ion-containing gas stream would be approximately the same temperature as the ambient gas within the resonator. Without wishing to be bound by theory, when the ion-containing gas stream and the ambient gas within the resonator are at approximately the same temperature, potential issues with buoyancy of the ion-containing stream and therm al -related acousticmedium interactions can be avoided.

[0086] Aspects of the present disclosure are directed to an apparatus for manipulation of a gaseous ion beam comprising: an ion source having an outlet configured to release the gaseous ion beam at a flow rate along a first path; a resonator configured to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path; and an ion detector.

[0087] In some embodiments, the ion source comprises a plasma ionization source, e.g., a flowing atmospheric pressure afterglow (FAP A) source or a direct analysis in real time (DART) source. In some embodiments, the ion source employs electrospray ionization (ESI),nanoelectrospray ionization (nESI), desorption electrospray ionization (DESI), atmospheric- pressure chemical ionization (APCI), or atmospheric-pressure photoionization (APPI).

[0088] In some embodiments, the flow rate comprises between about 0.0001 L min'1and about 0.1 L min'1, between about 0.1 L min'1and about 0.2 L min'1, between about 0.2 L min'1and about 0.3 L min'1, between about 0.3 L min'1and about 0.4 L min'1, between about 0.4 L min'1and about 0.5 L min'1, between about 0.5 L min'1and about 0.6 L min'1, between about 0.6 L min'1and about 0.7 L min'1, between about 0.7 L min'1and about 0.8 L min'1, between about 0.8 L min'1and about 0.9 L min'1, between about 0.9 L min'1and about 1.0 L min'1, between about 1.0 L min'1and about 1.1 L min'1, between about 1.1 L min'1and about 1.2 L min'1, between about 1.2 L min'1and about 1.3 L min'1, or between about 1.4 L min'1and about 1.5 L min'1.

[0089] In some embodiments, the apparatus further comprises a discharge gas inlet configured to receive a discharge gas and release it to a discharge chamber of the ion source. Suitable discharge gases comprise helium, argon, or nitrogen.

[0090] In some embodiments, the resonator comprises a first transducer and a first reflector. In some embodiments, the resonator comprises a first transducer and a second transducer. In some embodiments, the apparatus further comprising a second resonator. In some embodiments, the second resonator comprises a third transducer and a second reflector. In some embodiments, the second resonator comprises a third transducer and a fourth transducer.

[0091] In some embodiments, the resonator is configured to produce a resonance frequency between about 1 kHz and about 5 kHz, between about 5 kHz and about 10 kHz, between about 10 kHz and about 15 kHz, between about 15 kHz and about 20 kHz, between about 20 kHz and about 25 kHz, between about 25 kHz and about 30 kHz, between about 30 kHz and about 35 kHz, between about 35 kHz and about 40 kHz, between about 40 kHz and about 45 kHz, between about 45 kHz and about 50 kHz, between about 50 kHz and about 55 kHz, between about 55 kHz and about 60 kHz, between about 60 kHz and about 65 kHz, between about 65 kHz and about 70 kHz, between about 70 kHz and about 75 kHz, between about 75 kHz and about 80 kHz, between about 80 kHz and about 85 kHz, between about 85 kHz and about 90 kHz, between about 90 kHz and about 95 kHz, or between about 85 kHz and about 100 kHz.

[0092] In some embodiments, the ion detector comprises a mass spectrometer, an ion charge- coupled device, or a Faraday collector. In some embodiments, the ion detector comprises an inlet positioned opposite to the outlet and at least partially aligned with the first path. In some embodiments, ion detector comprises an inlet positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path by up to about 1 mm, up to about 2 mm, up to about 3 mm, up to about 4 mm, up to about 5 mm, up to about 6 mm, up to about 7 mm, up to about 8 mm, up to about 9 mm, or up to about 10 mm.

[0093] Aspects of the present disclosure are directed to methods of deflecting a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer(s) sufficient to at least partially deflect the gaseous ion beam around the antinode; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

[0094] In some embodiments, the peak voltage is between about 5 Vp.pand about 10 Vp.p, between about 10 Vp.pand about 15 Vp.p, between about 15 Vp.pand about 20 Vp.p, between about 20 Vp.p and about 25 Vp.p, between about 25 Vp.pand about 30 Vp.p, between about 30 Vp-p and about 35 Vp.p, between about 35 Vp.pand about 40 Vp.p, between about 40 Vp.pand about 45 Vp.p, between about 45 Vp.pand about 50 Vp.p, between about 50 Vp.pand about 55 Vp.p, between about 55 Vp.pand about 60 Vp.p, between about 60 Vp.pand about 65 Vp.p, between about 65 Vp.pand about 70 Vp.p, between about 70 Vp.pand about 75 Vp.p, between about 75 Vp.p and about 80 Vp.p, between about 80 Vp.pand about 85 Vp.p, between about 85 Vp.p and about 90 Vp.p, between about 90 Vp.pand about 95 Vp.p, between about 95 Vp.pand about 100 Vp.p, between about 100 Vp.pand about 105 Vp.p, between about 105 Vp.pand about 110 Vp.p, between about 110 Vp.pand about 115 Vp.p, between about 115 Vp.pand about 120 Vp.p, between about 120 Vp.pand about 125 Vp.p, between about 125 Vp.pand about130 Vp.p, between about 130 Vp.pand about 135 Vp.p, between about 135 Vp.pand about140 Vp.p, between about 140 Vp.pand about 145 Vp.p, between about 145 Vp.pand about150 Vp.p, between about 150 Vp.pand about 155 Vp.p, between about 155 Vp.pand about160 Vp.p, between about 160 Vp.pand about 165 Vp.p, between about 165 Vp.pand about170 Vp.p, between about 170 Vp.pand about 175 Vp.p, between about 175 Vp.pand about180 Vp.p, between about 180 Vp.pand about 185 Vp.p, between about 185 Vp.pand about190 Vp.p, between about 190 Vp.pand about 195 Vp.p, between about 195 Vp.pand about200 Vp.p, between about 200 Vp.pand about 205 Vp.p, between about 205 Vp.pand about210 Vp.p, between about 210 Vp.pand about 215 Vp.p, between about 215 Vp.pand about220 Vp.p, between about 220 Vp.pand about 225 Vp.p, between about 225 Vp.pand about230 Vp.p, between about 230 Vp.pand about 235 Vp.p, between about 235 Vp.pand about240 Vp.p, between about 240 Vp.pand about 245 Vp.p, between about 245 Vp.pand about250 Vp.p, between about 250 Vp.pand about 255 Vp.p, between about 255 Vp.pand about260 Vp.p, between about 260 Vp.pand about 265 Vp.p, between about 265 Vp.pand about270 Vp.p, between about 270 Vp.pand about 275 Vp.p, between about 275 Vp.pand about280 Vp.p, between about 280 Vp.pand about 285 Vp.p, between about 285 Vp.pand about290 Vp.p, between about 290 Vp.pand about 295 Vp.p, or between about 295 Vp.pand about300 Vp.p.

[0095] Referring now to FIG. 1 A-1D, ion deflection was experimentally visualized within an ultrasonic resonator according to some embodiments of the present disclosure. Referring now to FIG. 1 A, some embodiments of the present disclosure are directed to system 100 for ion beam 103 mapping that comprises ion source 101, transducers 102, and mass spectrometer inlet 104. In some embodiments, the outer diameter of the transducers 102 was 16 mm, which can be used as a graphical scale. Still referring to FIG. 1 A, in some embodiments, ion beam 103 is deflected between two antinodes 105. Additional information can be found in Examples 1 and 2.

[0096] Referring now to FIG. IB, measured relative sound pressure level (SPL) was calculated based on the decibel definition. In some embodiments, the number reflects the relative, rather than absolute, SPL reading. An exemplary acoustic sensing circuit is shown in FIG. 8 and comprises clock source 801, gate driver 802, MOSFET 803, isolation network 804, coupling transformer 805, matching inductor 806, transducer 807, and monitoring network 808. The ion trajectory of O2 at m / z 32 in the absence (FIG. 1C) and presence (FIG. ID) of the standing acoustic wave within the resonator was graphed. Still referring to FIG. ID, the simultaneously measured acoustic pressure field 115 is superimposed with the ion trajectory. The origin, (x, y, z), is defined by the outlet of the ion source, where (x = 0, z = 0) is defined on the center line aligned with the outlet, and the (y = 0) is defined at a point 5-mm away from the source outlet.

[0097] Without the presence of the acoustic field, the ion trajectory was nearly straight towards the mass spectrometer inlet (FIG. 1 C), which is expected given the laminar gas flow exiting the course. With C>2+at m / z 32 as an example, presence of a standing acoustic field immediately deflected ions away from their original trajectory (FIG. ID). The superimposed acoustic field contour and the deflected ion trajectory indicated that the ions followed the static pressure gradient, found in the node of the resonator. A similar effect was also observed for (H2O)2H+at m / z 37 (see FIGs. 10 A- 10C). Notably, the strength of the acoustic field used here was quite weak. In fact, it was only capable of levitating a -2 mm diameter polystyrene foam bead with a mass of ~50 pg or -5% of water with equivalent volume. Levitating a water droplet would require a sound pressure greater than 100 SPL-unit (-120 Vp.p) on the current scale, implying the SPL-unit used here is similar to the true dB unit. This finding indicates that ions or an ion-containing stream are more sensitive to acoustic fields than larger, neutral objects. Ion deflection requires significantly less acoustic power compared to levitation.

[0098] Without wishing to be bound by theory, one aspect that is unlikely to cause acoustic- induced ion deflection is the possible electric field inside the acoustic resonator. In the deflection experiment shown above, the voltage on the transducers were -30 Vp.p, which translates to maximum possible electric field strength of 1.6 V / mm, which is several orders of magnitude lower that that used in electric-field-based ion deflectors, despite the voltage drop on the transducer by sound emissions. Furthermore, these transducers have a grounded case and mesh covering the speaker, so there was no measurable electric field in the resonator area.

[0099] Again without wishing to be bound by theory, another possibility that has been ruled out is the direct gas deflection and the consequential ion movements due to the carrier-role of the discharge gas. To measure this possibility, a trace amount of acetone vapor was added to the discharge camber as a contrast agent to directly visualize the gas stream in the acoustic field through defocusing shadowgraphy (Example 3).

[0100] Without wishing to be bound by theory, one possible hypothesis for the cause of acoustic ion manipulation is the additional long-range interaction force due to the presence of ions. More specifically, the effective distance of electrostatic forces or Coulombic forces are significantly greater than that of van der Waals forces (e.g., London dispersion force, Keesom force and Debye forces). The consequent increments in the effective collision cross-sectionincreases. More specifically, the compressibility of an ion-containing gas stream, i.e., this case, became greater.

[0101] Referring now to FIG. 2, the defocusing shadowgraphy method was used for direct observation of a gas stream travelling through an antinode (bright regions in panel b) within the acoustic resonator described in the exemplary embodiments above. The gas velocity and the voltage applied on the transducer remain unchanged to the ion deflection experiment.

[0102] Aspects of the present disclosure are directed to methods of gating a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer(s) sufficient to block a percentage of ions from the gaseous ion beam from entering the inlet of the mass spectrometer.

[0103] In some embodiments, the percentage is between about 5% and about 10%, between about 10% and about 15%, between about 15% and about 20%, between about 20% and about 25%, between about 25% and about 30%, between about 30% and about 35%, between about 35% and about 40%, between about 40% and about 45%, between about 45% and about 50%, between about 50% and about 55%, between about 55% and about 60%, between about 60% and about 65%, between about 60% and about 70%, between about 70% and about 75%, between about 75% and about 80%, between about 80% and about 85%, between about 85% and about 90%, between about 90% and about 95%, or between about 95% and about 100%.

[0104] Having demonstrated that the presence of an acoustic field could deflect ions, which is similar to an ion gate but with an improved efficiency as described in the exemplary embodiments above, the acoustic pressure was increased, by changing the transducer voltages, to reveal a more complete picture of the acoustic-ion interaction. Referring now to FIG. 3 A, the outlet of the ion source 111 and the inlet of the mass spectrometer 114 were aligned with each other, increasing the ion transmission / detection. In this manner a gating mode can be achieved whereby antinode 105 gates ion beams 103 from reaching the inlet ofthe mass spectrometer 114. Referring now to FIG. 3B, upon careful inspection, ion signal with respect to the transducer voltage shows a dependency on ion identity, e.g., m / z and / or collision cross-section, was observed. The solid markers are the experimentally measured data, while the solid traces are sigmoidal fits to these data. The value of the transducer peakvoltage was same as the maximum sound pressure in SPL-unit as discussed above. Still referring to FIG. 3B, the gating response is shown for C>2+, (H2O+NH3+H)+, protonated acetone (CsHeO+H) , and a pronated methanol acetonitrile cluster (CH3OH+CH3CN+H) at m / z 32, 36, 59, and 74, respectively. These ions were selected because they have different chemical origin. One obvious feature is that protonated acetone at m / z 59 was deflected at a weaker acoustic field compared to other species. Without wishing to be bound by theory, it is possible that the permanent dipole associated with the carbonyl group on acetone results stronger intermolecular interactions compared to other ambient species, which could be reflected as changes in gas compressibility that can be further translated into a greater ionacoustic sensitivity. Again without wishing to be bound by theory, ions that stemmed from the same chemical origin exhibited similar acoustic responses (e.g., NH at m / z 18, H2ONH4 at m / z 36, (H2O)2*H+at m / z 37 (see FIG. 14), suggesting that these ions were produced inside the mass spectrometer, but existed in a clustered form outside.

[0105] Aspects of the present disclosure are directed to methods of focusing a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a first resonator to generate a first node and a first antinode along a second path that intersects with the first path, wherein the node is positioned at least partially within the first path; and configuring a second resonator to generate a second node and a second antinode along a third path that intersects with the first path, wherein the second node is positioned at least partially within the first path. In some embodiments, the third path intersects the second path.

[0106] While the disclosure above used a one-dimensional standing acoustic wave for ion manipulation, more complex two- and three-dimensional acoustic patterns can be utilized to enhance the ion-optic capabilities of AIM shown above (z.e., gating, focusing, deflection, and ion separation). Aspects of the present disclosure are also directed to manipulating gaseous ion beams using travelling waves. In some embodiments of ion focusing, the field structure shown in FIGs. 4A and 17 can be achieved with four ultrasonic transducers 102. Based oncalculations, the dimension of this planar resonator should have produced a hollow nodal structure in the center than allows ions to flow through a confined region. However, the experimentally determined sound-pressure distribution was more complicated (FIG. 4C, 3D views are shown in FIGs. 18A and 18B). Nonetheless, the desired structures were still obtained (FIG. 4C, node ABCD). By aligning the outlet of the ion source towards one node channel (z.e., point A in FIG. 4C), the spatial distribution of an ion at m / z 37 (z.e., (H2O)2*H+) was mapped. Compared to the monotonic ion decay further away from the ion source without the acoustic field (FIG. 10B), the presence of resonance acoustic field generated a “hot spot” at which the ion abundance was significantly higher than the rest of the regions.

[0107] Semi-quantitatively, the effect of ion focusing can be assessed by aligning the mass-spectrometer inlet 114 in-line with the ion source outlet 111 at the focal point, z.e., an absolute distance of 7.5 mm or -2.5 mm on the relative axis (FIG. 17). By enabling and disabling the acoustic field, the relative abundances of example ions, C>2+at m / z 32 and (H2O)2*H+at m / z 37 increased significantly. The absolute abundances of m / z 32 and 37 were increased by 50% and 300%, respectively.

[0108] Ion-acoustic interactions provide approaches to manipulate charged species in the open air, reducing the magnitude of voltages and / or magnetic fields for high-pressure ion optics. Moreover, the wave-nature of sound and the recent advances in ultrasound phased array can lead to a generalized platform, where complicated ion guides can be synthesized in real-time and in situ. Furthermore, the underlying mechanism of ion-acoustic responses appeared to pertain to the collision cross-section theoretical framework, which is the foundation of EVIS and similar differential mobility apparatus. Namely, exploiting the ionacoustic interactions might lead to analytical strategies that are more flexible and efficient.

[0109] Aspects of the present disclosure are directed to characterization of an acoustic ion gate, beginning with a comparison across detection methods(z.e., vacuum pull and external electric fields).

[0110] An lonCCD was used to provide spatial information about changes to the ion beam path after interaction with the antinode that could lead to an ion-gate effect. Conditions for the ionization source and acoustic field were chosen to maximize signal stability and AIM interactions. For these experiments, the acoustic field was operated at 37.8 kHz, with 20 Vp.psine waves on each transducer. The ionization source used a discharge gas flow rate of 1 Lmin'1, a discharge current of 3 mA, and an electrical bias on the front plate of +50 V. The support gas flow rate was selected to improve mass transport of ions from the source to detector, while the discharge current was kept low to prevent possible photon interference at the lonCCD detector. The electrical bias was selected for two purposes: to provide a potential difference from source to detector that would aid in mass transport, and to enhance the unipolarity of the ion beam towards positive ions.

[0111] Referring now to FIG. 22A, initially, the lonCCD was aligned parallel to the direction of acoustic field propagation (FAPA source conditions were a flow rate of 0.75 L min'1, a discharge current of 3 mA, and a front plate bias of 50 V. The acoustic field was driven with sine waves at 37.8 kHz, 20 Vp.p). The center of the antinode was aligned in the path of the ion beam. However, with an acoustic antinode present, the ion beam was shifted 2 mm above or below the neutral beam position. The direction of beam shift was determined by the source position — if the source was aligned to be slightly above the antinode, the ion beam shifted to 2 mm above, and if the source was slightly below the antinode, the ion beam shifted to 2 mm below. Cumulatively, these shifts indicate approximately 4 mm of vertical space that the ions could not pass through, which corresponds to the distance between nodes in a standing acoustic wave at 37.8 kHz.

[0112] Referring now to FIG. 22B, the lonCCD was then aligned perpendicular to the acoustic field structure to determine whether the beam shift occurred in multiple dimensions. In this alignment, ion signal decreased by 88% without any horizontal shift to the beam position. The decrease in signal is attributed to the ion beam being deflected above or below the detector pixels, which are only 1.5-mm tall and therefore smaller than the distance between nodes and antinodes (2 mm). This orientation most closely resembled the use of alternate detectors, such as the Faraday collector and MS, where gate function also depends on the deflection of ions outside of an acceptance region. However, some signal is still observed on the lonCCD after deflection, indicating that some ions can pass through the antinode region.

[0113] The observation of changes to the ion beam in the y and x planes established a baseline of ion gate function that could be compared with the use of different detection methods based on transmission through the closed gate. Transmission through the open gate is assumed to be 100%, as there is no physical obstruction in the ion beam path, unlike electrostatic gates. Closed gate transmission was calculated as shown in Equation 1:Equation 1%T 100

[0114] where %T is the transmission, Io is the signal when the gate is open, and I is the signal when the gate is closed. For example, transmission was calculated to be 12.8% for the horizontal lonCCD experiment, based on the integrated ion current across the detector. For the Faraday collector and mass spectrometer, transmission was calculated based on ion current or ion count rate, respectively. The transmission through an antinode was determined to be 18.2±2.0% when observed with a Faraday collector, and 66.5±2.8% when observed with a MS (FIGs. 23 A-23B).

[0115] Ionization source and acoustic field parameters were not re-optimized for the Faraday collector or MS, rather the same conditions were used from the lonCCD experiments.Smaller differences in transmission (z.e., between lonCCD and Faraday collector) can be attributed to the ionization source conditions. The conditions were chosen for signal stability on the lonCCD without an acoustic field present. Certain parameters, such as front plate bias and flow rate, provide the same mass transport and polarity benefits for the lonCCD and Faraday plate. Discharge current, however, was minimized to ensure that the plasma ionization source did not produce photons that would interfere with the lonCCD readings. Without wishing to be bound by theory, as the Faraday collector is not sensitive to light, it is likely that the discharge current parameter was not correctly optimized for that detection technique. The most notable discrepancies in transmission are between the Faraday-based detectors and the mass spectrometer. The pull of the vacuum environment of the mass spectrometer through the atmospheric-pressure interface produces a negative pressure region and offers an additional force to the ions towards the MS inlet. Without wishing to be bound by theory, ion transmission with an MS detector could have been higher because the vacuum can help pull the ions through the antinode. Again without wishing to be bound by theory, the vacuum of the MS inlet could pull in slow-moving ions after they have been deflected.

[0116] As mass spectrometry is a widely used and popular ion spectroscopy technique, optimizing the source and field conditions for AIM gating of an API-MS instrument was chosen to focus on. First, the effect of acoustic field strength was observed. For this experiment, arbitrary ionization source conditions that gave stable signal on the MS were chosen. The acoustic gate was formed from the interference of two sine waves with an amplitude of 20 Vp.p, which led to a combined amplitude of 40 Vp.pin the antinode. At lowamplitudes, such as 0-20 Vp.p, little change was observed in the total ion chronogram (FIG. 24). However, at 30 Vp.psignal was reduced by ca. 50%, and then almost completely blocked at 40 Vp.p. The driving voltage of a transducer can be related to acoustic power as shown in Equation 2:Equation 2

[0117] where Pavgis the average acoustic power, Fpeak is the peak voltage of the sine wave, and R is the resistance of the transducer. As such, increasing the driving voltage of the transducers will increase the output acoustic power in a squared relationship, which forms a stronger acoustic field and leads to the deflection of more ions. Acoustic power in the antinode has also previously been linked to the density of objects which can be manipulated with sound, where denser objects require more power. The relation between acoustic power and transmission indicates that the alignment of source, antinode, and detector is advantageously along the center axis of the three components, as that is where the driving voltage will be at its peak potential. It is unlikely that the acoustic field strength is responsible for the discrepancy between the detection methods, as ion signal decreased dramatically in these experiments with a drive voltage of 20 Vp.p, the same as was used in the method comparison experiments.

[0118] For a FAPA source, control of the discharge current, support gas flow rate, and / or applied electrical biases can help achieve a stable ion signal. Discharge current was not observed to have an impact on gate transmission in one embodiment. The FAPA source can be operated at currents between 3-25 mA without leading to significant changes in ion gate function in some embodiments. While higher discharge currents can lead to a greater number density of ions in the beam, there are no significant changes to plasma structure or the produced atmospheric reagent ions, which, without wishing to be bound by theory, can explain why minimal impact on AIM gating was observed.

[0119] Support gas flow rate and external electric fields are parameters for the kinetic properties of the ion beam as it exits the FAPA source. A higher support gas flow rate leads to a higher average linear velocity of ions based on Equation 3:Equation 3 Q = vA

[0120] Where Q is the gas flow rate (in cm3s'1), v is the linear velocity (in cm / s), and A is cross sectional area of the gas tube (in cm2). Generally, transmission through an acoustic antinode ion gate increases as average ion linear velocity increases (FIG. 25A). There is a small discrepancy between the slowest two velocities, 38.1 and 76.2 cm s'1, but it is not statistically significant.

[0121] The application of an electrical potential to the ionization source can also impact the kinetic properties of the ion beam. By floating the exit capillary of the FAPA between 0 V and 100 V, the ions will be directed to a counter electrode, the detector, with different velocities based on the potential difference. Ion velocity and electric field can be related by Equation 4:Equation 4 vd= KE

[0122] where vdis the drift velocity of an ion, K is the ion mobility, and E is the electric field strength. This equation is used because ion mobility reflects the properties of the ions at atmospheric pressure and temperature. As the ion beam is composed of many different ions with different mobilities, an overall velocity for the bulk ion beam based on the electric field cannot be calculated, and the discussion is based on the applied electric field, which relates linearly to an increase in velocity for all species. At atmospheric pressure, it is known that after the initial acceleration of the ions from the external DC-field given to the ions by the electrical bias of the ionization source, the ions travel with a constant velocity due to the short mean free path. As in the case of ion velocity determined by flow rate, an increase in the ion velocity determined by an external electric field led to an increased transmission of ions through the antinode gate (FIG. 25B).

[0123] Without wishing to be bound by theory, it is likely that the increased transmission observed at higher flow rates and applied potentials is a result of fewer ions being deflected. Changes to these parameters can be related to a variety of physical properties of the ions through average ion velocity, such as momentum or kinetic energy through typical kinematic equations. Previous work has shown that increases to the average velocity of hollow microparticles in solution decrease the efficacy of acoustic trapping with a single lens focused ultrasound. This is due to the increased drag forces on the particle approaching the trapping force of the transducer used, so that the trapping force is no longer enough to lead to interaction between the particle and speaker. Again without wishing to bebound by theory, it is likely that the ions move at too high a speed and have counteracting forces to the deflection mechanism, which leads them to either be deflected at shallower angles or pass directly through the antinode as high gas flow rates and potential biases.

[0124] The identification of flow rate and electrical bias as sensitive parameters for controlling ion gate transmission improves the ability of an acoustic ion gate to interface with API-MS. Because gating was more effective for slow ions, the ionization source was operated with a support gas flow rate of 0.5 LPM and no applied electrical bias. A discharge current of 15 mA was used to generate a sufficient number of ions for reasonable signal stability. Using these improved conditions, the gate transmission as observed with MS was 2.0 ± 0.9% for a single ion gate (FIG. 26). Unlike a BNG, which can obstruct ion passage by up to 20% even when the gate is open, the acoustic ion gate allows all ions through when in the open state. Not only does this increase ion throughput for the open gate, it also eliminates risks of contamination due to interactions with a physical surface. Additionally, with gating times estimated to be on the scale of tens of microseconds, it is on par with the operation time required for IMS, typically between 50 and 200 ps. While traditional BNGs can be floated at least 40 V above the drift potential in IMS instruments to reach the onset voltage for gating, at sufficient ion velocities the acoustic gate blocked more than 97% of ions at low driving voltages using commercially available power supplies.

[0125] In operation, BNGs and TPGs are capable of blocking more than 99% of ions. In order to be comparable to this, a second acoustic ion gate was introduced for little additional cost. In these experiments, the acoustic ion gates were powered from the same function generator, and no additional materials were required aside from a second set of transducers. By using the second gate, transmission was decreased to 0.2±0.1% for a flow rate of 0.5 L min'1(FIG. 27A-27B). Without wishing to be bound by theory, non-zero transmission was attributed to ions penetrating through the antinode due to their unique speed or alignment with the acoustic field (ie., ions within the laminar flow of the beam can move faster or slower than the average linear velocity of the beam and can be aligned with the area between the node and antinode rather than with the antinode itself.) As such, the introduction of another gate can cause ions to undergo multiple deflection events and further decrease transmission. Again without wishing to be bound by theory, the presence of two gates can help to decrease transmission even with higher flow rates. For a flow rate of 1 L min'1, thetransmission through two gates is 3.8±1.1%. However, the source-to-detector distance was increased to 16 mm.

[0126] Ion gates are part of ion spectroscopic instrumentation, such as for IMS and MS. Both techniques frequently analyze small molecules, such as pesticides or narcotics. Aniline is a common commodity chemical and could be of interest due to its presence in many organic syntheses. In order to confirm that acoustic ion gates are capable of interacting with small molecules not produced in the atmosphere by the ionization source, the ion beam was doped with aniline (m / z 94.07) and the transmission of the analyte was observed. Referring now to FIG. 28, protonated aniline ions exhibited transmission of 10.9 ± 9.2% through the ion gate, comparable to the bulk ion transmission of 8.8±6.6%.

[0127] Some embodiments of the present technology, therefore, provide a low-power, acoustic-based ion gate. Unlike several popular ion gates, such as a Bradbury-Nielsen or Tyndall gate, an acoustic ion gate would be optically transparent in some embodiments, which reduces the possibility of analyte ion loss or sample contamination due to physical collisions with the gate mesh. Because there are no electric fields in some embodiments, this gate will not impact sensitivity due to the presence of a depletion region. Additionally, some embodiments can be constructed and powered with commercial electronics, eliminating the need for custom built components. Some embodiments of an acoustic ion gate according to the present technology are capable of operating at high pressures, such as for IMS analysis, and can interface with atmospheric pressure inlets, such as on a mass spectrometer.EXAMPLES

[0128] Example 1. Experimental Geometry

[0129] The setup for acoustic ion manipulation with mass spectrometry detection and acoustic pressure field mapping is shown in FIG. 5. The acoustic resonator that comprises two ultrasonic transducers 102 was aligned in a face-to-face fashion. Compared to the transducer-reflector configuration, this two-transducer resonator produced acoustic field that was concentric with the transducers, while retaining the center symmetry for the z-direction (z.e., up and down). The outlet of the ion source was pointed at the center-of-symmetry of the acoustic resonator.

[0130] An additional ultrasonic transducer 106 was used to measure the sound strength, while a mass spectrometer was used to detect ion signals. The sensing transducer 106 and mass spectrometer remained stationary throughout this work. The sensing transducer 106 was connected to a peak detector in passive mode as described below. The sound guide 116 was a section of stainless-steel tubing with an outer diameter of 0.8 mm to reduce the probing slit width, which provided adequate spatial resolution for acoustic measurements. For mapping measurements, the acoustic resonator and the ion source 201 were placed on a xyz translational stage, and were moved together with respect to the MS inlet 104 and ultrasonic sensor. The x=0 mm and z=0 mm planes were defined when the outlet of the ionization source 201 and the inlet of the mass spectrometer 104 were in-line with each other. Meanwhile, the y=0 mm plane was defined by the distance between the ends of the ion source outlet and mass spectrometer inlet. A minimal distance was 8 mm to avoid overloading the mass spectrometer. At this position, the tip of the acoustic sensor was at the geometric center of the acoustic resonator.

[0131] Chemicals: Ultrahigh purity helium (UHP300, Airgas, Radnor, PA) and compressed nitrogen (NI300, Airgas, Radnor, PA) were used as discharge gas. All other detected species mentioned in this work were due to the laboratory air.

[0132] Ionization source: A flowing atmospheric-pressure afterglow (FAP A) source 201 was used to generate the ion beam, which primarily comprised of positively charged reagent ions such as protonated water cluster (z.e., (H20)n*H+) and oxygen radical cation (z.e., O2 ). The geometry of the FAPA 201 source was described elsewhere. Briefly, a FAPA source 201 of pin-to-capillary geometry was used (FIG. 5), which comprise a capillary anode and a stainless steel pin cathode. In most examples shown in this work, nitrogen gas at 0.40 L min'1was supplied into the chamber of the FAPA source 201 as discharge medium. Otherwise, it will be specified in the context when helium is used. Referring now to FIG. 6, a FAPA source 201 can comprise cathode needle 202, discharge gas inlet 204, discharge chamber 205, and anode capillary 211 from which ion beam 103 is released. FAPA sources 201 commonly use helium as discharge gas. It is also possible to operate this source with nitrogen. However, due to the high discharge barrier of molecular gas, the voltage across the two electrodes were significantly higher, while the current was reduced. Consequently, the glow discharge with helium was replaced by corona-to-glow discharge when nitrogen was used. In the present disclosure, the voltage that was applied on the FAPA assembly (including a 10 k currentlimiting resistor) was 4.94 kV (5 kV); the current through this assembly was 0.67 qA. The typical time-averaged mass spectrum acquired with the mass spectrometer can be found in FIG. 7, which shows a typical background mass spectrum acquired with a nitrogen-based FAPA source on the LTQ-XL mass spectrometer is shown.

[0133] Mass Spectrometer: In this study, a unit-resolution linear ion trap mass spectrometer (LTQ-XL, Thermo Scientific, San Jose, CA) was used to record low-mass ion signals. The mass range was set to m / z 20-200 with the injection RF set to 15 (manufacture unit) to be able to detect ions down to m / z 20. The capillary temperature and maximum injection time were set to 275 °C and 20 ms, respectively. Because the reagent ions were the primary targets, no further tuning was performed on the instrument.

[0134] Ultrasonic Driver: An ultrasonic driver circuit was built in-house to power all the acoustic sources used in this work (FIG. 8). The main clock signal at 40 kHz was generated with a pulse-width modulation (PWM) controller integrated circuit (TL494) 801. To avoid thermal accumulation on the clock circuit, which can cause frequency drifting, a gate driver IC (MC34151) 802 was used to buffer the signal. A power metal-oxide-semiconductor fieldeffect transistor 803 (MOSFET, IRF540N) was used to drive the coupling transformer 805 (home-made ferrite-core transformer), where the secondary was used to power the transducers 807 (TCT40-16). In this study, the number of transducers used were one, two, and four. In each individual case, matched inductors 806 were used to ensure the 40 kHz resonance frequency. Additionally, a monitoring network 808 was used to manually regulate the voltage applied across the transducer(s) 807; this voltage dictates the travel distance of the piezo surface, which is essentially the output sound pressure.

[0135] In order to map the acoustic field, an independent ultrasonic transducer (TCT40-16) 901 was used for sensing. Referring now to FIG. 9, the transducer 901 was encapsulated in a 3D-printed cavity with a capillary (1.0 mm OD, 0.9 mm ID, stainless steel) protruding to improve the spatial resolution. The probing site of this capillary 902 was aligned with the mass spectrometer inlet capillary. This sensing assembly was not calibrated; thus, absolute sound pressure was not measured. However, it was sufficient to determine the spatial distribution of the acoustic field. To record the relative sound pressure, a peak detector 903 was used (FIG. 9). The sensor transducer 901 was capacitively coupled to a buffer operating amplifier (Op-Amp, LM324) 904, which also had a gain of -100 to amplify the signal. Thereafter, the signal was sent through a peak detector circuit 903, from which the maximalamplitude can be determined. The final peak voltage was then digitized by the on-board analog-to-digital converter on a microcontroller (MCU, ATMEGA2560, Atmel) with 10 bit resolution. Notably, for each sampling point, the peak values were recorded and averaged 500 times to gain statistical validity. To achieve this goal, the MCU sent out a trigger signal to the MOSFET to discharge the accumulation capacitor in the peak detection loop every time after reading out the peak voltages. The final digitized peak voltages were sent to a controlling computer, synchronizing with the position (x, y, z) of the motorized stage. The firmware on the MCU was programmed and compiled with Atmel Studio 7.0.

[0136] Example 2. Trajectories of (EEO^’EE With and Without Resonance Acoustic Field

[0137] Referring now to FIGs. 10A-10C, ion trajectories of (EhO^’EH- at m / z 37 without (FIG. 10B) and with (FIG. 10C) the resonance acoustic field. The ion trajectories were determined from the same dataset as shown in FIG. 1.

[0138] Example 3. Schlieren Setup Geometry and Additional Results

[0139] The visualization of the transient acoustic field and the neutral gas stream was achieved by a variant of a phase-sensitive technique termed defocusing (DF) shadowgraphy, where a detailed description of the theory and quantitative capability are given elsewhere. Briefly, the DF shadowgraphy setup similar components compared to a co-linear schlieren imaging system. The difference is that the razor blade at the first focal point or at the Fraunhofer plane was removed. Instead, the objective in front of the imaging sensor was defocused, which acted as a retarder that translates the commonly invisible phase distortion into observable fringes.

[0140] Referring now to FIG. 11, a schematic of the setup of the defocusing (DF) shadowgraphy system is shown. The distance between the lens and the image focusing position is denoted by the symbol “ .” The emission spectrum and the quantum efficiency of the image detector (EO5012M, Edmund Optics) are shown in panel a) with solid and open circle traces, respectively. In panel b), a sectional view of the assembly housing the acoustic resonator and the ion source is provided. The outer diameter of the transducer is 16 mm, serving as a reference.

[0141] In this optical characterization section, a function generator (DG1062Z, Rigol) was used to power the ultrasonic transducers instead of the home-built power supply for accuratetime-base synchronization. A sine wave with various peak-to-peak voltages was used to drive the ultrasonic transducers. The sine wave was strictly clocked to 40 kHz. Meanwhile, the second channel on the function generator was used to generate a pulse-width modulation signal at 39.9996 kHz, i.e. Af = 0.4 Hz, with a pulse width of 3 ps to enable stroboscopic acquisition on the camera. The camera was operated at 4 frames per second (maximum possible framerate at 2560x1920) with the internal trigger to record the gas stream and the transient acoustic field simultaneously.

[0142] In the present disclosure, the ultrasonic transducers were operated under quite low power even though the peak-to-peak voltages used here are higher than the manufacturer- recommended value (usually 10V).

[0143] Referring now to FIG. 12, energy spectrum analysis was used to extract the resonant acoustic field. The averaged camera image is shown in on the left. The graph at the top right shows the time-dependent averaged pixel signal in the box bounded by comers 1201. The graph at the bottom right presents the energy spectrum after Fourier transform of the averaged pixel signal in the box bounded by comers 1202. Referring now to FIG. 13, the left and right panels illustrate the real and imaginary parts, respectively, of the image with a band-pass filter at 0.4 Hz.

[0144] Example 4. Additional Ion-Specific Response Functions

[0145] Referring now to FIG. 14, ion-specific response functions of water-related ions are graphed. The dashed black curve is the sigmoidal fit for the listed species.

[0146] In addition to the in-line mode, some embodiments employ another configuration for a deflection mode, which was achieved by shifting the inlet of the mass spectrometer vertically by half of the wavelength of the acoustic standing wave. Referring now to FIG. 15 A, a schematic shows the offset of the inlet capillary 114 from the ion exit 111 (e.g., 2.23 mm), antinodes 105, and ion trajectories 103. The ions would travel on the extension line of the ion outlet capillary 111, and ended up on top of the mass-spectrometer inlet 114 (FIG. 15 A). Consequently, the ions would not be detected without the presence of the resonance acoustic field. Referring now to FIG. 15B, by increasing the strength of the acoustic field, ions began to be detected until a certain point. Further increasing the strength causes blockage effect (FIG. 15B Transducer Vp.pgreater than about 32 V). Without wishing to be bound by theory, the ions could no longer pass through the acoustic filed due to the highfield strength. In this sense, the response curves for different ions were fitted with a double- sigmoidal function, where one contributed to the ion deflection towards the ion detector, and another one for blocking the ions from entering the resonance acoustic field. However, and again without wishing to be bound by theory, comparing to the blockage mode (FIGs. 3 A- 3B), the mass dependency was no longer as straight forward due to the complicated physical processes involved.

[0147] Aspects of the present disclosure are directed to methods of separating a first ion and a second ion in a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer sufficient to enrich a concentration of the first ions from the gaseous ion beam that enter the inlet of the mass spectrometer; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

[0148] Example 5. 2D Transducer Array

[0149] Rather than using sophisticated phased arrays, a simple 2D resonator was designed for an initial test. The geometry of the framework can be found in FIG. 16. In some embodiments, the structure is central symmetric. In some embodiments, the factor “a” can be set to about 37 mm. This prototype was 3D-printed in-house with polylactic acid (PLA). Due to the limited available space for this setup, the framework was designed to be compact. However, the high density of PLA comparing to air can be considered sound-hard surface, which caused severe reflection within the central cavity of this framework. Thus, the experimentally determined sound-pressure distribution was quite different from the simulated case, where a center node was not found. Instead, the node-A (FIG. 4C) that contained the expected feature was used.

[0150] After determining the focal point of this 2D array, the setup shown in FIG. 17 was used. Note that the outlet 111 of the FAP A source 201 was placed inside the cavity of framework 122. The reason for this arrangement was due the periodic distribution of nodes and antinodes. The node-A was not only surrounded by antinodes in the x-z plane (parallel to the array). Along the y-axis, there were two adjacent antinodes as well. If the FAPA source201 is shifted back (far from the 2D resonator), the antinode between the 2D resonator and FAPA outlet would block the ions from entering the node. Consequently, the ions were blocked from being detected by the mass spectrometer.

[0151] In contrast, exiting the 2D array was not restrained by the acoustic field. The acoustic field blocks the ions from entering but does not consume the momentums of the ions that were already inside the resonance acoustic field. Thus, the ion spatial distribution was mapped and the focal point was experimentally determined (FIG. 4B). While mapping the ion distribution as show in FIG. 4B, the FAPA outlet 111 was already at this position.Throughout this work, the FAPA source 201 and the ultrasound resonators were moved together at all times.

[0152] Referring now to FIGs. 18A-18B, 3D views of the hollow node are shown. The node- A was the same as that shown in FIG. 4A. FIG. 19 shows the corresponding ion counts.

[0153] Calculating the total ion abundance: Based on the typical mass spectrum shown in FIG. 7 and assuming the transmission efficiency of this mass spectrometer to 10'6, the total ion abundance would be on the order of 109~l 010ions / s. From the diameter the atmospheric- pressure inlet of the mass spectrometer, e.g., 0.67 mm, and the first-stage vacuum, e.g., 0.9 Torr or 1.2 mBar, the inlet flow rate can be calculated to be roughly 0.7 L / min. Thus, the ion abundance can be determined to be on the order of 1010cm’3. Comparing to the number of neutral molecules at atmospheric pressure, ~2.7xl019cm’3, the ion abundance is nine-orders of magnitudes lower.

[0154] Example 6. Acoustic Ion Gates

[0155] Ionization source: A pin-to-capillary Flowing Atmospheric Pressure Afterglow (FAPA) ionization source was used to generate a partially ionized beam of gas. The exact source design used here has been described in detail elsewhere. Briefly, an atmospheric- pressure glow discharge was maintained between a pin cathode and tube-shaped anode in a gastight chamber. The plasma was operated at a discharge current between 5 and 15 mA with a custom-built high-voltage power supply (Prosolia, Inc. Indianapolis, IN) and sustained in an ultra-high purity helium support gas (99.999% pure, AirGas, Radnor, PA) with a flow rate between 0.5 and 1.5 L min'1(model C50L-AL-DD-2-PV2-V0-SCR, Sierra Instruments, Monterey, CA). For some experiments, a voltage between 0 and 100 V was applied to theexit capillary of the FAPA with a DC-power supply (model 230-01F, Spellman, Valhalla, NY).

[0156] Standing acoustic wave ion gate: A standing acoustic wave was formed with two opposing piezoelectric ultrasonic speaker (TCT40-16R / T, HiLetgo, Guangdong, China) spaced 16 mm apart. The transducers were driven at 37.8 kHz with a 20 Vp.psine wave (unless otherwise stated) from an arbitrary waveform generator (model AG2052F, Owon Technology Inc., Zhangzhou, China). Standing wave formation was confirmed with an oscilloscope (InfiniiVision DSQ-X 2024A, Keysight Technologies Inc., Santa Rosa, CA). To do this, one transducer was used as a transmitter and connected to the function generator and oscilloscope. The second transducer was used as a receiver and connected to only the oscilloscope. The transmitted and received waveform could be visualized on the oscilloscope and real time adjustments could be made to achieve the desired interference pattern. Additionally, a piece of Styrofoam was levitated in the node of the acoustic field. Levitated Styrofoam beads were also used to identify the locations of nodes and antinodes 105 for alignment with the ionization source and detector. The spacing of nodes in a standing wave formed with 37.8 kHz speakers was predicted to be -4 mm and validated based on Styrofoam levitation.

[0157] Ion detection methods: Three different detection methods were used to analyze ion beam behaviors. A Q-Exactive mass spectrometer (Thermo Scientific, Bremen, Germany) was used to detect ion species and signal. Relevant instrument parameters include injection time, which was set to 200 ms, and resolution, which was set to 70,000. The mass range was m / z 50 to m / z 200 record low-mass ions produced from the FAPA source. To observe ion behavior without the effects of a vacuum, a Faraday plate with a picoammeter (model 51097A, Keithley Instruments Inc., Cleveland, OH) was used for ion-current measurements. An insulating mask with a 7 -mm2round hole was placed over the Faraday plate to limit the detection region. Ion beam position and signal were monitored using an lonCCD detector array (IDS-2030, OI Analytical, College Station, TX) 124. The ID-array detector 124 consists of 2126 pixels, each 21 pm by 1500 pm with -88% pixel area ratio, and was oriented in different directions to observe ion profiles. In vertical alignment, the array 124 was oriented in the same direction as the longitudinal acoustic wave propagation, while in horizontal alignment the lonCCD 124 was oriented orthogonal to the acoustic-field structure(FIG. 21). During gate operation, the ionization source 201 and detector 124 were separated by ~16 mm to accommodate the transducers 102 for standing wave formation.

[0158] Ion beam doping with aniline: The ion beam was doped with aniline (INFO) by flowing ultra-high purity nitrogen (99.999% pure, AirGas, Radnor, PA) over a small amount contained in a small vial. Fused silica capillaries were punched through the lid of the vial to provide an inlet for the nitrogen gas, and an outlet for the gas containing aniline. The flow rate of the nitrogen gas was controlled using a mass flow controller (GR116-06, Fathom Technologies, Georgetown, TX) and was typically 60 cm3min'1. The outlet of the vial was placed between the exit capillary of the FAPA source and the acoustic resonator.

[0159] Although the invention has been described and illustrated with respect to exemplary embodiments thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions and additions can be made therein and thereto, without parting from the spirit and scope of the present invention.

Claims

CLAIMS1. An apparatus for manipulation of a gaseous ion beam comprising: an ion source having an outlet configured to release the gaseous ion beam at a flow rate along a first path; a resonator configured to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path; and an ion detector.

2. The apparatus of claim 1, wherein the ion source comprises a plasma ionization source.

3. The apparatus of claim 2, wherein the plasma ionization source comprises a flowing atmospheric pressure afterglow source.

4. The apparatus of claim 1, wherein the ion source comprises a direct analysis in real time (DART) source.

5. The apparatus of claim 1, wherein the ion source comprises an electrospray ionization (ESI) source, a nanoelectrospray ionization (nESI) source, a desorption electrospray ionization (DESI) source, and atmospheric-pressure chemical ionization (APCI) source, or an atmospheric-pressure photoionization (APPI) source.

6. An apparatus as in any preceding claim, wherein the flow rate comprises between about 0.0001 L min'1and about 0.1 L min'1, between about 0.1 L min'1and about 0.2 L min'1, between about 0.2 L min'1and about 0.3 L min'1, between about 0.3 L min'1and about 0.4 L min'1, between about 0.4 L min'1and about 0.5 L min'1, between about 0.5 L min'1and about 0.6 L min'1, between about 0.6 L min'1and about 0.7 L min'1, between about 0.7 L min'1and about 0.8 L min'1, between about 0.8 L min'1and about 0.9 L min'1, between about 0.9 L min'1and about 1.0 L min'1, between about 1.0 L min'1and about 1.1 L min'1, between about 1.1 L min'1and about 1.2 L min'1, between about 1.2 L min'1and about 1.3 L min'1, or between about 1.4 L min'1and about 1.5 L min'1.

7. An apparatus as in any preceding claim further comprising a discharge gas inlet configured to receive a discharge gas and release it to a discharge chamber of the ion source.

8. The apparatus of claim 7, wherein the discharge gas comprises helium, argon, or nitrogen.

9. An apparatus as in any of the preceding claims, wherein the resonator comprises a first transducer and a first reflector.

10. An apparatus as in any one of claims 1-8, wherein the resonator comprises a first transducer and a second transducer.

11. An apparatus as in any of the preceding claims further comprising a second resonator.

12. The apparatus of claim 11, wherein the second resonator comprises a third transducer and a second reflector.

13. The apparatus of claim 11, wherein the second resonator comprises a third transducer and a fourth transducer.

14. An apparatus as in any of the preceding claims, wherein the resonator is configured to produce a resonance frequency between about 1 kHz and about 5 kHz, between about 5 kHz and about 10 kHz, between about 10 kHz and about 15 kHz, between about 15 kHz and about 20 kHz, between about 20 kHz and about 25 kHz, between about 25 kHz and about 30 kHz, between about 30 kHz and about 35 kHz, between about 35 kHz and about 40 kHz, between about 40 kHz and about 45 kHz, between about 45 kHz and about 50 kHz, between about 50 kHz and about 55 kHz, between about 55 kHz and about 60 kHz, between about 60 kHz and about 65 kHz, between about 65 kHz and about 70 kHz, between about 70 kHz and about 75 kHz, between about 75 kHz and about 80 kHz, between about 80 kHz and about 85 kHz, between about 85 kHz and about 90 kHz, between about 90 kHz and about 95 kHz, or between about 85 kHz and about 100 kHz.

15. An apparatus as in any of the preceding claims, wherein the first path is colinear with the second path.

16. An apparatus as in any one of claims 1-14, wherein an angle between the first path and the second path is between about 0.01 degrees and about 5 degrees, between about 5 degrees and about 10 degrees, between about 10 degrees and about 15 degrees, between about 15 degrees and about 20 degrees, between about 20 degrees and about 25 degrees, between about 25 degrees and about 30 degrees, between about 30 degrees and about 35 degrees, between about 35 degrees and about 40 degrees, between about 40 degrees and about 45 degrees, between about 45 degrees and about 50 degrees, between about 50 degrees and about 55 degrees, between about 55 degrees and about 60 degrees, between about 60 degrees and about 65 degrees, between about 65 degrees and about 70 degrees, between about 70 degrees and about 75 degrees, between about 75 degrees and about 80 degrees, between about 80 degrees and about 85 degrees, between about 85 degrees and about 90 degrees, between about 90 degrees and about 95 degrees, between about 95 degrees and about 100 degrees, between about 100 degrees and about 105 degrees, between about 105 degrees and about 110 degrees, between about 110 degrees and about 115 degrees, between about 115 degrees and about 120 degrees, between about 120 degrees and about 125 degrees, between about 125 degrees and about 130 degrees, between about 130 degrees and about 135 degrees, between about 135 degrees and about 140 degrees, between about 140 degrees and about 145 degrees, between about 145 degrees and about 150 degrees, between about 150 degrees and about 155 degrees, between about 155 degrees and about 160 degrees, between about 160 degrees and about 165 degrees, between about 165 degrees and about 170 degrees, between about 170 degrees and about 175 degrees, or between about 175 degrees and about 180 degrees.

17. The apparatus of claim 16, wherein the angle is about 90 degrees.

18. An apparatus as in any of the preceding claims, wherein the ion detector comprises a mass spectrometer.

19. An apparatus as in any one of claims 1-17, wherein the ion detector comprises an ion charge-coupled device.

20. An apparatus as in any one of claims 1-17, wherein the ion detector comprises a Faraday collector.

21. An apparatus as in any of the preceding claims, wherein the ion detector comprises an inlet positioned opposite to the outlet and at least partially aligned with the first path.

22. An apparatus as in any one of claims 1-20, wherein the ion detector comprises an inlet positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path by up to about 1 mm, up to about 2 mm, up to about 3 mm, up to about 4 mm, up to about 5 mm, up to about 6 mm, up to about 7 mm, up to about 8 mm, up to about 9 mm, or up to about 10 mm.

23. A method of deflecting a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator comprises a transducer and is further configured to increase a peak voltage of the transducer sufficient to at least partially deflect the gaseous ion beam around the antinode; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

24. The method of claim 23, wherein the peak voltage is between about 5 Vp.pand about10 Vp-p, between about 10 Vp.pand about 15 Vp.p, between about 15 Vp.pand about20 Vp-p, between about 20 Vp.pand about 25 Vp.p, between about 25 Vp.pand about30 Vp-p, between about 30 Vp.pand about 35 Vp.p, between about 35 Vp.pand about40 Vp-p, between about 40 Vp.pand about 45 Vp.p, between about 45 Vp.pand about50 Vp-p, between about 50 Vp.pand about 55 Vp.p, between about 55 Vp.pand about60 Vp-p, between about 60 Vp.pand about 65 Vp.p, between about 65 Vp.pand about70 Vp-p, between about 70 Vp.pand about 75 Vp.p, between about 75 Vp.pand about80 Vp-p, between about 80 Vp.pand about 85 Vp.p, between about 85 Vp.pand about90 Vp-p, between about 90 Vp.pand about 95 Vp.p, between about 95 Vp.pand about100 Vp-p, between about 100 Vp.pand about 105 Vp.p, between about 105 Vp.pandabout 110 Vp.p, between about 110 Vp.pand about 115 Vp.p, between about 115 Vp.pand about 120 Vp.p, between about 120 Vp.pand about 125 Vp.p, between about 125 Vp.p and about 130 Vp.p, between about 130 Vp.pand about 135 Vp.p, between about 135 Vp.p and about 140 Vp.p, between about 140 Vp.pand about 145 Vp.p, between about 145 Vp.pand about 150 Vp.p, between about 150 Vp.pand about 155 Vp. p, between about 155 Vp.pand about 160 Vp.p, between about 160 Vp.pand about 165 Vp.p, between about 165 Vp.pand about 170 Vp.p, between about 170 Vp.pand about 175 Vp.p, between about 175 Vp.pand about 180 Vp.p, between about 180 Vp.pand about 185 Vp.p, between about 185 Vp.pand about 190 Vp.p, between about 190 Vp.p and about 195 Vp.p, between about 195 Vp.pand about 200 Vp.p, between about 200 Vp.p and about 205 Vp.p, between about 205 Vp.pand about 210 Vp.p, between about 210 Vp.pand about 215 Vp.p, between about 215 Vp.pand about 220 Vp. p, between about 220 Vp.pand about 225 Vp.p, between about 225 Vp.pand about 230 Vp.p, between about 230 Vp.pand about 235 Vp.p, between about 235 Vp.pand about 240 Vp.p, between about 240 Vp.pand about 245 Vp.p, between about 245 Vp.pand about 250 Vp.p, between about 250 Vp.pand about 255 Vp.p, between about 255 Vp.p and about 260 Vp.p, between about 260 Vp.pand about 265 Vp.p, between about 265 Vp.pand about 270 Vp.p, between about 270 Vp.pand about 275 Vp.p, between about 275 Vp.pand about 280 Vp.p, between about 280 Vp.pand about 285 Vp. p, between about 285 Vp.pand about 290 Vp.p, between about 290 Vp.pand about 295 Vp.p, or between about 295 Vp.pand about 300 Vp.p.

25. A method of gating a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned at least partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer sufficient to block apercentage of ions from the gaseous ion beam from entering the inlet of the mass spectrometer.

26. The method of claim 25, wherein the percentage is between about 5% and about 10%, between about 10% and about 15%, between about 15% and about 20%, between about 20% and about 25%, between about 25% and about 30%, between about 30% and about 35%, between about 35% and about 40%, between about 40% and about 45%, between about 45% and about 50%, between about 50% and about 55%, between about 55% and about 60%, between about 60% and about 65%, between about 60% and about 70%, between about 70% and about 75%, between about 75% and about 80%, between about 80% and about 85%, between about 85% and about 90%, between about 90% and about 95%, or between about 95% and about 100%.

27. A method of focusing a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a first resonator to generate a first node and a first antinode along a second path that intersects with the first path, wherein the node is positioned at least partially within the first path; and configuring a second resonator to generate a second node and a second antinode along a third path that intersects with the first path, wherein the second node is positioned at least partially within the first path.

28. The method of claim 27, wherein the third path intersects the second path.

29. A method of separating a first ion and a second ion in a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring a resonator to generate a node and an antinode along a second path that intersects with the first path, wherein the antinode is positioned atleast partially within the first path, and wherein the resonator is further configured to increase a peak voltage of the transducer sufficient to enrich a concentration of the first ion from the gaseous ion beam that enter the inlet of the mass spectrometer; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

30. An apparatus for manipulation of a gaseous ion beam comprising: an ion source having an outlet configured to release the gaseous ion beam at a flow rate along a first path; an acoustic field generator configured to generate a travelling acoustic wave along a second path that intersects with the first path; and an ion detector.

31. The apparatus of claim 30, wherein the ion source comprises a plasma ionization source.

32. The apparatus of claim 31, wherein the plasma ionization source comprises a flowing atmospheric pressure afterglow source.

33. The apparatus of claim 30, wherein the ion source comprises a direct analysis in real time (DART) source.

34. The apparatus of claim 30, wherein the ion source comprises an electrospray ionization (ESI) source, a nanoelectrospray ionization (nESI) source, a desorption electrospray ionization (DESI) source, and atmospheric-pressure chemical ionization (APCI) source, or an atmospheric-pressure photoionization (APPI) source.

35. An apparatus as in any one of claims 30-34, wherein the flow rate comprises between about 0.0001 L min'1and about 0.1 L min'1, between about 0.1 L min'1and about 0.2 L min'1, between about 0.2 L min'1and about 0.3 L min'1, between about 0.3 L min'1and about 0.4 L min'1, between about 0.4 L min'1and about 0.5 L min'1, between about 0.5 L min'1and about 0.6 L min'1, between about 0.6 L min'1and about 0.7 Lmin'1, between about 0.7 L min'1and about 0.8 L min'1, between about 0.8 L min'1and about 0.9 L min'1, between about 0.9 L min'1and about 1.0 L min'1, between about 1.0 L min'1and about 1.1 L min'1, between about 1.1 L min'1and about 1.2 L min'1, between about 1.2 L min'1and about 1.3 L min'1, or between about 1.4 L min'1and about 1.5 L min'1.

36. An apparatus as in any one of claims 30-35 further comprising a discharge gas inlet configured to receive a discharge gas and release it to a discharge chamber of the ion source.

37. The apparatus of claim 36, wherein the discharge gas comprises helium, argon, or nitrogen.

38. An apparatus as in any one of claims 30-37, wherein the acoustic field generator comprises a first transducer and a first acoustic absorbing material.

39. An apparatus as in any one of claims 30-37, wherein the acoustic field generator comprises a first transducer and a second transducer.

40. An apparatus as in any one of claims 30-39 further comprising a second acoustic field generator.

41. The apparatus of claim 40, wherein the second acoustic field generator comprises a third transducer and a second acoustic absorbing material.

42. The apparatus of claim 40, wherein the second acoustic field generator comprises a third transducer and a fourth transducer.

43. An apparatus as in any one of claims 30-42, wherein the acoustic field generator is configured to produce a travelling acoustic wave having a frequency between about 1 kHz and about 5 kHz, between about 5 kHz and about 10 kHz, between about10 kHz and about 15 kHz, between about 15 kHz and about 20 kHz, between about20 kHz and about 25 kHz, between about 25 kHz and about 30 kHz, between about30 kHz and about 35 kHz, between about 35 kHz and about 40 kHz, between about40 kHz and about 45 kHz, between about 45 kHz and about 50 kHz, between about50 kHz and about 55 kHz, between about 55 kHz and about 60 kHz, between about60 kHz and about 65 kHz, between about 65 kHz and about 70 kHz, between about70 kHz and about 75 kHz, between about 75 kHz and about 80 kHz, between about 80 kHz and about 85 kHz, between about 85 kHz and about 90 kHz, between about 90 kHz and about 95 kHz, or between about 85 kHz and about 100 kHz.

44. An apparatus as in any one of claims 30-43, wherein the first path is colinear with the second path.

45. An apparatus as in any one of claims 30-43, wherein an angle between the first path and the second path is between about 0.01 degrees and about 5 degrees, between about 5 degrees and about 10 degrees, between about 10 degrees and about 15 degrees, between about 15 degrees and about 20 degrees, between about 20 degrees and about 25 degrees, between about 25 degrees and about 30 degrees, between about 30 degrees and about 35 degrees, between about 35 degrees and about 40 degrees, between about 40 degrees and about 45 degrees, between about 45 degrees and about 50 degrees, between about 50 degrees and about 55 degrees, between about 55 degrees and about 60 degrees, between about 60 degrees and about 65 degrees, between about 65 degrees and about 70 degrees, between about 70 degrees and about 75 degrees, between about 75 degrees and about 80 degrees, between about 80 degrees and about 85 degrees, between about 85 degrees and about 90 degrees, between about 90 degrees and about 95 degrees, between about 95 degrees and about 100 degrees, between about 100 degrees and about 105 degrees, between about 105 degrees and about 110 degrees, between about 110 degrees and about 115 degrees, between about 115 degrees and about 120 degrees, between about 120 degrees and about 125 degrees, between about 125 degrees and about 130 degrees, between about 130 degrees and about 135 degrees, between about 135 degrees and about 140 degrees, between about 140 degrees and about 145 degrees, between about 145 degrees and about 150 degrees, between about 150 degrees and about 155 degrees, between about 155 degrees and about 160 degrees, between about 160 degrees and about 165 degrees, between about 165 degrees and about 170 degrees, between about 170 degrees and about 175 degrees, or between about 175 degrees and about 180 degrees.

46. The apparatus of claim 45, wherein the angle is about 90 degrees.

47. An apparatus as in any one of claims 30-46, wherein the ion detector comprises a mass spectrometer.

48. An apparatus as in any one of claims 30-47, wherein the ion detector comprises an ion charge-coupled device.

49. An apparatus as in any one of claims 30-47, wherein the ion detector comprises a Faraday collector.

50. An apparatus as in any one of claims 30-49, wherein the ion detector comprises an inlet positioned opposite to the outlet and at least partially aligned with the first path.

51. An apparatus as in any one of claims 30-49, wherein the ion detector comprises an inlet positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path by up to about 1 mm, up to about 2 mm, up to about 3 mm, up to about 4 mm, up to about 5 mm, up to about 6 mm, up to about 7 mm, up to about 8 mm, up to about 9 mm, or up to about 10 mm.

52. A method of deflecting a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an acoustic field generator to generate a travelling acoustic wave along a second path that intersects with the first path, wherein the acoustic field generator comprises a transducer and is further configured to increase a peak voltage of the transducer sufficient to at least partially deflect the gaseous ion beam from the first path; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

53. The method of claim 52, wherein the peak voltage is between about 5 Vp.pand about10 Vp-p, between about 10 Vp.pand about 15 Vp.p, between about 15 Vp.pand about20 Vp-p, between about 20 Vp.pand about 25 Vp.p, between about 25 Vp.pand about30 Vp-p, between about 30 Vp.pand about 35 Vp.p, between about 35 Vp.pand about40 Vp.p, between about 40 Vp.pand about 45 Vp.p, between about 45 Vp.pand about50 Vp.p, between about 50 Vp.pand about 55 Vp.p, between about 55 Vp.pand about60 Vp.p, between about 60 Vp.pand about 65 Vp.p, between about 65 Vp.pand about70 Vp.p, between about 70 Vp.pand about 75 Vp.p, between about 75 Vp.pand about80 Vp.p, between about 80 Vp.pand about 85 Vp.p, between about 85 Vp.pand about90 Vp.p, between about 90 Vp.pand about 95 Vp.p, between about 95 Vp.pand about100 Vp.p, between about 100 Vp.pand about 105 Vp.p, between about 105 Vp.pand about 110 Vp.p, between about 110 Vp.pand about 115 Vp.p, between about 115 Vp.pand about 120 Vp.p, between about 120 Vp.pand about 125 Vp.p, between about 125 Vp.p and about 130 Vp.p, between about 130 Vp.pand about 135 Vp.p, between about 135 Vp.p and about 140 Vp.p, between about 140 Vp.pand about 145 Vp.p, between about 145 Vp.pand about 150 Vp.p, between about 150 Vp.pand about 155 Vp. p, between about 155 Vp.pand about 160 Vp.p, between about 160 Vp.pand about 165 Vp.p, between about 165 Vp.pand about 170 Vp.p, between about 170 Vp.pand about 175 Vp.p, between about 175 Vp.pand about 180 Vp.p, between about 180 Vp.pand about 185 Vp.p, between about 185 Vp.pand about 190 Vp.p, between about 190 Vp.p and about 195 Vp.p, between about 195 Vp.pand about 200 Vp.p, between about 200 Vp.p and about 205 Vp.p, between about 205 Vp.pand about 210 Vp.p, between about 210 Vp.pand about 215 Vp.p, between about 215 Vp.pand about 220 Vp. p, between about 220 Vp.pand about 225 Vp.p, between about 225 Vp.pand about 230 Vp.p, between about 230 Vp.pand about 235 Vp.p, between about 235 Vp.pand about 240 Vp.p, between about 240 Vp.pand about 245 Vp.p, between about 245 Vp.pand about 250 Vp.p, between about 250 Vp.pand about 255 Vp.p, between about 255 Vp.p and about 260 Vp.p, between about 260 Vp.pand about 265 Vp.p, between about 265 Vp.pand about 270 Vp.p, between about 270 Vp.pand about 275 Vp.p, between about 275 Vp.pand about 280 Vp.p, between about 280 Vp.pand about 285 Vp. p, between about 285 Vp.pand about 290 Vp.p, between about 290 Vp.pand about 295 Vp.p, or between about 295 Vp.pand about 300 Vp.p.

54. A method of gating a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path;configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring an acoustic field generator to generate a travelling acoustic wave along a second path that intersects with the first path, and wherein the acoustic field generator comprises a transducer and is further configured to increase a peak voltage of the transducer sufficient to block a percentage of ions from the gaseous ion beam from entering the inlet of the mass spectrometer.

55. The method of claim 54, wherein the percentage is between about 5% and about 10%, between about 10% and about 15%, between about 15% and about 20%, between about 20% and about 25%, between about 25% and about 30%, between about 30% and about 35%, between about 35% and about 40%, between about 40% and about 45%, between about 45% and about 50%, between about 50% and about 55%, between about 55% and about 60%, between about 60% and about 65%, between about 60% and about 70%, between about 70% and about 75%, between about 75% and about 80%, between about 80% and about 85%, between about 85% and about 90%, between about 90% and about 95%, or between about 95% and about 100%.

56. A method of focusing a gaseous ion beam comprising: configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and at a second position along the first path; and configuring a first acoustic field generator to generate a first travelling acoustic wave along a second path that intersects with the first path; and configuring a second acoustic field generator to generate a second travelling acoustic wave along a third path that intersects with the first path,.

57. The method of claim 56, wherein the third path intersects the second path.

58. A method of separating a first ion and a second ion in a gaseous ion beam comprising:configuring an outlet of an ion source to be positioned at a first position along a first path; configuring an acoustic field generator to generate a travelling acoustic wave along a second path that intersects with the first path, and wherein the acoustic field generator comprises a transducer and is further configured to increase a peak voltage of the transducer sufficient to enrich a concentration of the first ion from the gaseous ion beam that enter the inlet of the mass spectrometer; and configuring an inlet of a mass spectrometer to be positioned opposite to the outlet and offset from the first path along an axis that is parallel to the second path.

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