Dual-frequency radiofrequency device for confining ions

Abstract

A radio frequency device for transverse confinement of ions in an ion region, comprising: a first set of electrodes arranged parallel to one another and arranged one behind the other along a direction of ion movement to define a first transverse boundary of the ion region, and which are supplied with a first radio-frequency voltage such that opposite phases of the first radio-frequency voltage are applied to adjacent electrodes of the first set; and a second set of electrodes arranged parallel to each other and arranged one behind the other along the direction of ion movement to define a second transverse boundary of the ion region, and which are supplied with a second radio-frequency voltage so that opposite phases of the second radio-frequency voltage are applied to adjacent electrodes of the second set, wherein the first and second transverse boundaries are opposite each other in a transverse direction of the ion region and the first radio-frequency voltage and the second radio-frequency voltage have different frequencies, wherein the electrodes of the first set have a relative distance equal to a relative distance of the electrodes of the second set, characterized in that that the arrangement of the electrodes of the second set is offset relative to the electrodes of the first set along the direction of ion movement by a predetermined amount.

Description

Field of the invention

[0001] The invention relates to radio frequency (RF) devices with stacked electrodes for transverse ion confinement, for example radio frequency ion guide systems and radio frequency ion traps, and systems incorporating these radio frequency devices, for example mass spectrometric systems. State of the art

[0002] High-frequency devices that include a stack of perforated electrodes are well-known in the field of mass spectrometry and ion mobility. Opposite phases of a high-frequency voltage (typically at a frequency of several hundred kilohertz up to several megahertz and a voltage of several hundred volts) are alternately applied to the perforated electrodes, which are arranged along a longitudinal axis of the high-frequency device. The forces generated by the high-frequency potentials repel the ions passing through the electrode openings. The effect of the so-called pseudopotentials generated by the high-frequency potentials and different operating procedures are described, for example, in an article by Gerlich (1992; Advances in Chemical Physics Series, Vol. LXXXII; Title: „INHOMOGENEOUS RF FIELDS: A VERSATILE TOOL FOR THE STUDY OF PROCESSES WITH SLOW IONS“) and in patent No. US 5 572 035 A.The ions are prevented from escaping through the gaps between the electrodes and are therefore transversely confined within the radiofrequency device. DC potentials or transient DC potentials can be additionally applied to the hole electrodes to actively drive the ions along the axis of the radiofrequency device or to store them along the axis inside the radiofrequency device.

[0003] Radiofrequency devices with stacked electrodes include both radiofrequency ion funnels, which are typically used to capture spatially distributed ions at a wide-open entrance and guide them into a narrow opening at the exit (Patent No. US 6 107 628 A), and radiofrequency ion tunnels, which contain electrodes with a constant opening area and which can be used to generate ion packets and actively propel them through the radiofrequency ion tunnel by applying multi-phase low-frequency or transient DC voltages to the electrodes, or as collision cells with an active propulsion (Patent No. US 6 693 276 B2).

[0004] Another example is disclosed in patent no. US 7,391,021 B2. Here, the radio-frequency devices each contain a stack of hole electrodes that allow the cross-sectional profile of an ion beam to be shaped to match the acceptance profile of a downstream region of the device. For this purpose, at least some of the hole electrodes do not have circular openings, but rather openings that shape the cross-sectional profile of the emerging ion beam in the desired manner. It is possible to obtain elliptical beam cross-sections, split ion beams, or ion beams focused in the form of a thin thread at the exit of the hole electrode stack.

[0005] The pseudopotential generated by the radiofrequency devices contains ripples from potential wells between the stacked electrodes. These pseudopotential wells tend to trap ions, especially when a damping gas is present, and can only be overcome by additional axial forces acting on the ions.

[0006] US 2015 / 0206731 A1, which is considered to represent the closest prior art, discloses an ion guide device for a mass spectrometer. In one design, a plurality of electrode sets are arranged along a central axis. Each electrode set is ring-shaped and comprises two electrode segments. The distribution of the respective electrode sets among the electrode segments gradually changes along the central axis. The electrode segments of a respective electrode set are subjected to different phases of an RF potential, and neighboring electrode segments are similarly subjected to different phases of the RF potential. The electrode segments of an electrode set are located at a uniform position along the central axis.

[0007] DE 10 2016 188 292 A1 describes an ion guide for a mass spectrometer, comprising two adjacent ion guide sections, each approximately forming a circular ring segment in cross-section perpendicular to an axial direction. The ion guide comprises electrodes arranged parallel to one another and extending along the axial direction, with adjacent electrodes connected in phase opposition to an RF voltage. The electrodes of the various ion guide sections can also be subjected to RF voltages of different frequencies.

[0008] US 2020 / 0294783 A1 discloses a linear ion trap mass analyzer with eight electrodes arranged around a central axis. The eight electrodes run parallel to this central axis. In one design, two adjacent electrodes are supplied with one phase of a first RF voltage, and the electrodes closest to these electrodes are supplied with the opposite phase of this first RF voltage. Opposite, two adjacent electrodes are supplied with one phase of a second RF voltage, and the electrodes closest to these electrodes are supplied with the opposite phase of this second RF voltage. The eight electrodes are arranged along the central axis between two end cap electrodes. Brief description of the invention

[0009] The invention provides a radio-frequency device for transverse ion confinement in an ion region. The radio-frequency device includes a first set of electrodes arranged parallel to one another along a direction of ion movement (longitudinal axis) to define a first transverse boundary of the ion region, and supplied with a first radio-frequency voltage such that opposite phases of the first radio-frequency voltage are applied to adjacent electrodes of the first set. The radio-frequency device further includes a second set of electrodes arranged parallel to one another along the direction of ion movement to define a second transverse boundary of the ion region, and supplied with a second radio-frequency voltage such that opposite phases of the second radio-frequency voltage are applied to adjacent electrodes of the second set.The first and second transverse boundaries are opposite each other in a transverse direction of the ion region, and the first radio-frequency voltage and the second radio-frequency voltage have different frequencies. The radio-frequency device includes first and second generators configured to generate the first and second voltages of different frequencies. The electrodes of the first set have a relative spacing equal to a relative spacing of the electrodes of the second set, wherein the arrangement of the electrodes of the second set is offset relative to the electrodes of the first set by a predetermined amount along the direction of ion movement.

[0010] Applying two different frequencies to two opposing sets of electrodes, in accordance with the invention in combination with a spatial offset between the sets of electrodes, has the advantage of generating two pseudopotential distributions independently of each other, thus minimizing the pseudopotential wells between the electrodes along the axis. The radiofrequency device according to the invention allows the focusing of ions toward the central surface between the first and second boundaries without preventing their movement in the central surface, particularly along the longitudinal axis. In contrast, the prior art describes focusing the ions toward a line without taking their movement along the line into account.

[0011] In an exemplary embodiment, the frequencies applied to the two sets of electrodes differ by more than 10% and may differ by more than 20%, or more advantageously by more than 50%. Preferably, the ratio of the two frequencies is not an integer to minimize resonant excitation of ion motion, for example, f1 / f2 = 1.2 / 0.86 or 1.8 / 1.2. The mean of the two frequencies may be between 0.3 and 10 MHz and is preferably about 1 MHz. The operating pressure may be less than 5,000 Pa, more preferably less than 1,000 Pa, and is typically between 200 and 700 Pa.

[0012] The electrodes of the respective first and second sets have a relative distance S along the ion movement, and the first and second transverse boundaries have a relative distance D from each other in the transverse direction, wherein the ratio D / S is preferably less than 10 in at least part of the radio-frequency device along the direction of ion movement, more preferably less than 5, most preferably between 1.5 and 3. A small D / S ratio has the advantage that the ions are not only confined in the ion region between the first and second boundaries, but are also focused in the transverse direction onto a central area between the first and second boundaries. The distances, as well as the D / S ratio, can be constant or can vary locally along the entire direction of ion movement.The radio-frequency device may, for example, have large separations or a large D / S ratio at the input, whereas the separations or the D / S ratio are relatively smaller towards the output or at the output. This variation allows for a larger storage volume at the input and stronger focusing towards the central area at the output, where ions are, for example, focused through a pinhole to a downstream pumping stage or analyzed according to their mass or mobility. In one version of the invention, the effective pseudopotential generated by the first and second electrodes is symmetric, and a Taylor series of the effective pseudopotential contains only even-order terms. In an asymmetric version, the Taylor series of the combined pseudopotentials contains even and odd terms, with the first-order (linear) term associated with a constant force toward one of the electrode sets.The amplitudes of the first and second high-frequency voltages can be different, in particular to adapt the effective pseudopotential to the symmetric version.

[0013] In an exemplary embodiment of the invention, the electrodes of the first set have a spacing corresponding to the spacing of the electrodes of the second set, and the arrangement of the electrodes of the second set is offset relative to the electrodes of the first set along the axis by half the spacing.

[0014] In a first embodiment, the electrodes of the first and second sets jointly enclose a cross-sectional profile of the ion region. The electrodes of the first set can at least partially interlock with the electrodes of the second set in an overlap region. The overlap area is preferably less than 20% of the inner boundary of the ion region.

[0015] In a second embodiment, the electrodes of the first and second sets do not completely enclose the ion region. Additional electrodes or electrode segments of the first and second electrodes are supplied with repulsive DC potentials to transversely confine the ions in the ion region in portions of the ion region that are not enclosed by the electrodes of the first or second sets. The repulsive DC potentials applied to the additional electrodes or electrode segments preferably have a DC offset relative to the DC potentials applied to adjacent electrodes of the first and second sets. The DC offset may be constant or vary along the axis.

[0016] A plurality of electrodes of the first and second sets may have a rod-shaped section with a round cross-section. The ratio of the diameter of the round cross-section to the spacing of the rod-shaped sections is preferably about two to three (2:3).

[0017] The cross-sectional profile of the ion region can be convex, i.e. for any two points within the cross-sectional profile, all points along a line segment between the two points also lie within the cross-sectional profile. A convex cross-sectional profile can, for example, be round, oval, elongated rectangular, or elongated rectangular with rounded lateral sections. The cross-sectional profile can also be non-convex, for example shaped like a horseshoe, serpentine, or shaped like the space between a closed outer boundary and a closed inner boundary, such as a circular ring. One advantage of a non-convex cross-sectional profile is that the influence of one charged ion on another is reduced and the number of ions that can be stored is increased.

[0018] The ion region may have an elongated cross-sectional profile perpendicular to the axis with a long dimension and a short dimension. Furthermore, the elongated cross-sectional profile may have mirror symmetry with respect to a plane containing the long axis of the ion region and the long dimension. The cross-sectional profile of the ion region may be constant or vary along the long axis of the ion region. The cross-sectional profile at the entrance of the radiofrequency device may be larger than at the exit, for example, to form a funnel for collecting the ions and to spatially focus them at the exit of the ion region.

[0019] The radio-frequency device may further include a DC voltage generator configured to apply additional DC potentials to the electrodes of the first and second sets and / or the additional electrodes. The additional DC potentials are not applied to transversely store ions in the ion region. These additional DC potentials may be repulsive and applied to the electrode of the first and / or second set near the entrance and exit of the ion region such that the ions are temporarily stored in the ion region along the longitudinal axis. By applying the additional DC potentials, ions may, for example, be accelerated axially into or within a gas-filled radio-frequency device to induce fragmentation through collisions with gas molecules.Ions or fragment ions can either be stored or actively driven by the radiofrequency device using the axial fields generated with the additional DC potentials. The additional DC potentials can be time-dependent, for example, to first store ions and then release them from the radiofrequency device, or to vary the fragmentation energy for collision-induced dissociation (CID) of the ions over time. The additional DC potentials can be transient DC potentials to generate a traveling wave within the radiofrequency device. The DC potentials applied to the electrodes of the radiofrequency device can be generated via a resistor chain or by a plurality of DC power supplies.

[0020] The radio-frequency device can be used for different purposes, for example as an ion guide device, ion trap, fragmentation cell, ion mobility separator, in particular as a storage ion mobility separator or as an ion accelerator / reflector, for example in a time-of-flight mass analyzer.

[0021] The invention further provides a mass spectrometric system comprising an ion source, the radio frequency device according to the invention and a mass analyzer.

[0022] The ion source can generate ions using, for example, spray ionization (e.g., electrospray ionization (ESI) or thermal spray ionization), desorption ionization (e.g., matrix-assisted laser desorption / ionization (MALDI) or secondary ionization), chemical ionization (CI), photoionization (PI), electron impact ionization (EI), or gas discharge ionization.

[0023] The mass spectrometric system may further include an ion guide and / or an ion trap between the functional components, wherein the radiofrequency device is part of the ion guide and / or the ion trap. As described above, DC potentials may be applied to electrodes of the first and / or second set of the radiofrequency device to temporarily store the ions in the ion region along the longitudinal axis and / or to drive the ions through the ion region.

[0024] The mass analyzer can be, for example, a time-of-flight analyzer (preferably with orthogonal ion injection), an electrostatic ion trap, an RF ion trap, an ion cyclotron resonance ion trap, or a quadrupole mass filter. The mass analyzer is preferably a time-of-flight mass analyzer and includes at least one accelerator for orthogonal ion injection, a flight path, or a reflector. The radio-frequency device can be integrated into at least one of these components of the time-of-flight mass analyzer.

[0025] Furthermore, the mass spectrometric system may include an ion mobility separator between the ion source and the mass analyzer, wherein the ion mobility separator includes the radio-frequency device according to the invention. The ion mobility separator may, for example, be a TIMS (storage ion mobility separator), preferably including a gas flow along the longitudinal axis of the ion region and a DC voltage generator. The DC voltage generator is configured to supply DC potentials to the electrodes of the first and second sets of the radio-frequency device to generate a DC electric field gradient along the axis that counteracts the force of the gas flow, so that the ions are separated and stored according to ion mobility during an accumulation phase.The DC voltage generator is further configured to vary the DC potentials applied to the electrodes of the first and second sets such that ions are released from the ion mobility separator during an elution phase in time according to their ion mobility. The ion region of the DC voltage device incorporated in the TIMS preferably has an elongated cross-sectional profile perpendicular to the longitudinal axis with a long dimension and a short transverse dimension.

[0026] Furthermore, the mass spectrometric system can contain a fragmentation cell between the ion source and the mass analyzer, wherein the fragmentation cell contains the radiofrequency device according to the invention. The fragmentation cell is preferably placed between the ion mobility separator and the mass analyzer. The ions can be fragmented in the fragmentation cell, for example, by collision-induced dissociation (CID), surface-induced dissociation (SID), photodissociation (PD), electron capture dissociation (ECD), electron transfer dissociation (ETD), collision activation after electron transfer dissociation (ETcD), activated ion-electron transfer dissociation (AI-ETD), or fragmentation by reactions with highly excited or radical neutral particles.For example, the fragmentation cell may include a DC voltage generator configured to apply DC potentials to the electrodes of the first and / or second set along the axis such that ions are accelerated within or into the gas-filled radio frequency device and fragment ions resulting from the collision-induced dissociation are driven through the ion region.

[0027] In addition, the mass spectrometric system may include a mass filter, which may be located upstream of the fragmentation cell, particularly between the ion mobility separator and the fragmentation cell. An additional mass filter may be located upstream of the ion mobility separator. Furthermore, a separation device, such as a liquid chromatograph or an electrophoresis device, may be part of the mass spectrometric system or coupled to it. Short description of the drawings Fig. shows a first embodiment of a radio frequency device according to the invention, which is part of a storage ion mobility separator (TIMS). Fig. shows first upper and lower electrodes of the high frequency device of Fig. . Fig. shows a schematic side view of the upper and lower electrodes of the high-frequency device of Fig. and applying high-frequency potentials to them. Fig. shows a schematic side view of the upper and lower electrodes of the high-frequency device of Fig. and applying DC potentials to them. Fig. is a graphical representation of opposing axial forces on ions in the radio frequency device from Fig. . Fig. is a graphical representation showing the effective velocity components for different ion types in the radio frequency device from Fig. shows. Fig. is a graphical representation like the one in Fig. , which facilitates the elution of ions from the radiofrequency device Fig. shows. Fig. shows a second embodiment of a high-frequency device according to the invention with simplified electrodes compared to the first embodiment. Fig. shows first upper and lower electrodes of the high frequency device of Fig. . Fig. shows the first upper and lower electrodes of the high frequency device from Fig. in the xy plane. Fig. shows an alternative configuration to that shown in Fig. shown, in which the electrodes have a long parallel section near the center of the ion region and curved edges at the lateral ends. Fig. is a schematic view of a version of the high frequency device from Fig. in which the cross-sectional profile of an ion region changes along the z-direction. Fig. shows a third embodiment of the high-frequency device according to the invention with electrodes that carry exclusively direct voltage for confining ions in one of the transverse directions. Fig. is a schematic side view of the electrodes of the high-frequency device of Fig. which shows the application of high frequency potentials to them. Fig. is a schematic side view of the electrodes of the high-frequency device of Fig. which shows the application of DC potentials to them. Fig. is a schematic view of a version of the embodiment of Fig. in which the cross-sectional profile of an ion region changes along the z-direction. Fig. shows a fourth embodiment of the radio frequency device according to the invention, wherein the ion region is not completely enclosed by the electrodes of the radio frequency device. Fig. is a schematic view of a version of the embodiment of Fig. in which the cross-sectional profile of an ion region changes along the z-direction. Fig. shows a fifth embodiment of the radio frequency device according to the invention, wherein the ion region is non-convex and has a ring shape defined by the space between the coaxially aligned inner and outer electrodes. Fig. is a schematic view of a version of the embodiment of Fig. in which the cross-sectional profile of an ion region changes along the z-direction. Fig. shows a sixth embodiment of the radio frequency device according to the invention, wherein the ion region is non-convex and has a mainly arcuate shape. Fig. is a schematic view of a version of the embodiment of Fig. in which the cross-sectional profile of an ion region changes along the z-direction. Fig. is an embodiment of a radio frequency device having an ion region that is non-convex and has a mainly serpentine shape. Fig. shows a mass spectrometric system containing at least one radio frequency device according to the invention. Detailed description of the invention

[0028] A first embodiment of the high-frequency device according to the invention is shown in Fig. shown.

[0029] Fig. shows a radio-frequency device 100 that is part of a storage ion mobility separator (TIMS). The radio-frequency device 100 includes an upper electrode set 101 and a lower electrode set 102, each with electrodes 101-1 to 101-N and 102-1 to 102-N. The upper electrodes 101 engage the lower electrodes 102 along the z-direction, i.e., portions of the electrodes of the lower set 102 are arranged between sections of the electrodes of the upper set 101. The radio-frequency device 100 has an ion region 110 that has an elongated cross-sectional profile perpendicular to the z-direction with a long dimension along the y-direction and a short dimension along the x-direction. The electrodes of the first and second sets (101, 102) together enclose the convex cross-sectional profile of the ion region 110.

[0030] Ions enter from one side of the ion region 110 and eventually move to the opposite side. The direction of movement along the ion region 110 is defined as the longitudinal axis of the radiofrequency device 100 (z-direction). The ions are the molecular components of a sample to be analyzed that have been ionized and introduced into the ion region 110. This is typically done using an ionization source of a known type, such as an electrospray ion source, a matrix-assisted laser desorption (MALDI) ion source, or a chemical ionization (CI) ion source.

[0031] In a storage ion mobility separator (TIMS), ions are temporarily stored in the ion region 110 along the longitudinal axis of the radiofrequency device at positions that depend on their mobility. The ions are separated along the longitudinal axis of the radiofrequency device according to their ion mobility using opposing forces (first / second force) that generate opposing velocity components. At least one of the two axial forces has an ion mobility-dependent effect on the ions, and at least one of the two axial forces varies spatially along the longitudinal axis of the radiofrequency device.

[0032] During an accumulation phase, the opposing forces are adjusted such that an equilibrium point with zero velocity exists in the ion region 110 for each ion species of interest. Since a mobility-dependent force affects ion species with different mobility differently, the spatial position along the longitudinal axis of the radiofrequency device for which the velocity of an ion species is zero depends on the mobility K of that ion species. During a subsequent elution phase, the stored ion species are finally released from the ion region 110 by a change in one or both forces, which changes the velocity components. One after the other, the ion species no longer have an equilibrium point in the ion region 110 and elute from the ion region according to their mobility K.This relative change in the opposing axial forces can be progressive, so that ion species of increasing or decreasing mobility K gradually leave the TIMS. In addition to the opposing axial forces, the ions are transversely confined in the ion region 110 of the radiofrequency device.

[0033] As discussed in more detail below, the first force can be generated by a constant-velocity gas flow, while the second force can be generated via a DC electric field gradient that increases along the z-direction from zero to a maximum value on a plateau. The radiofrequency device provides the DC electric field gradient as well as transverse confinement of the ions in the ion region 110. The storage ion mobility separator (TIMS) operates at a pressure between 10 and 5,000 Pa, typically between 200 and 700 Pa.

[0034] Fig. shows the first upper electrode 101-1 and the first lower electrode 102-1, both of which are substantially longer in the long dimension (y-direction) than in the short dimension (x-direction). Each electrode includes an elongated portion (101a-1, 102a-1) and two extended portions (101b-1 and 102b-1) located at the ends of each electrode, extending in the x-direction, and having a generally flat shape with an arcuate edge facing the ion region 110. The extended portions of the upper electrode 101-1 partially overlap the extended portions of the lower electrode 102-1 in the xy plane. In the present embodiment, the elongated portions are rod-shaped with a round cross-section, although other electrode shapes may be used, for example, with a rounded cross-section facing only the ion region.The elongated portions of the upper and lower sets define first and second transverse boundaries of the ion region 110. The extended portions define left and right boundaries of the ion region 110.

[0035] Fig. shows a schematic side view (xz plane) of the upper electrodes 101 and the lower electrodes 102. In this embodiment, two different radio-frequency potentials (RF1, RF2) with different frequencies are used, with RF1 being applied to the electrodes 101 and RF2 to the electrodes 102. As shown in the figure, along the z-direction, the electrodes 101 alternate with the electrodes 102, and two antiphases are used for each of the radio-frequency potentials. For example, a first phase of RF1 (RF1+) is applied to each odd-numbered upper electrode (101-1, 101-3, ...), while an antiphase RF1- (which has a phase difference of 180° with respect to RF1+) is applied to the even-numbered upper electrodes (101-2, 101-4, ...). Similarly, a first phase of RF2 (RF2+) is applied to each odd-numbered lower electrode (102-1, 102-3, ...), while an opposite phase, RF2-, is applied to the even-numbered lower electrodes (102-2, 102-4, ...). An important advantage of applying radiofrequency potentials of two different frequencies to the electrode arrays on the two sides and offsetting the electrode arrays on both sides is that essentially no pseudopotential wells are formed within the ion region, especially along the long axis. Ions are focused by the pseudopotential (generated by applying the radiofrequency potential to the elongated sections) onto the central area between the elongated upper and lower sections without hindering their movement in the central area, especially along the long axis. Focusing into this central area is important because the mobility resolution of the TIMS separator increases with gas velocity, and the gas flow velocity is highest in the central area.The ions are further confined to the left and right by pseudopotentials generated by applying the radiofrequency potentials to the extended sections.

[0036] Fig. shows a schematic side view (xz plane) of the upper electrodes 101 and lower electrodes 102 and the DC potentials applied to the electrodes of both sets (101, 102). As shown in Figure 1, a first DC potential DC101-1 is applied to the first upper electrode 101-1, while a DC potential DC101-N is applied to the nth upper electrode 101-N. Similarly, a DC potential DC102-1 is applied to the first lower electrode 102-1, and a DC potential DC102-N is applied to the nth lower electrode 102-N. Additional DC potentials are applied to each of the other upper and lower electrodes.These DC potentials are constant over time during the accumulation phase, varied during the elution phase, and used to generate a DC electric field gradient along the z-direction to control the ions in the ion domain, as discussed in more detail below.

[0037] An example of this embodiment has the following parameters, although those skilled in the art will understand that this is only an example and that the parameters can be varied depending on the application. Although the operating pressure of the TIMS can range from 10–5,000 Pa (0.1–50 mbar), in this particular example it is approximately 300 Pa (3 mbar). The ion region has a z-direction length of 100 mm, a y-direction width of 40 mm, and an x-direction height of 4 mm. The number of upper electrodes 101 in this version is 40 and the number of lower electrodes 102 is also 40. The high-frequency potentials enable transverse confinement of the ions in the ion region in both the x and y directions, with RF1 having a frequency of 0.86 MHz and RF2 a frequency of 1.2 MHz or RF1 having a frequency of 1.2 MHz and RF2 a frequency of 1.7 MHz.The elongated sections are circular, rod-shaped electrodes with a diameter of approximately 2 mm and a distance of 3 mm from neighboring electrode structures (both above and below the ion region). The elongated electrodes are preferably integrated into a printed circuit board (PCB) and are supplied with DC and radiofrequency potentials via lines on the PCB. Finally, the gas flow velocity is approximately between 50 and 100 m / s.

[0038] The effect of the opposing axial forces on the ions in the laterally extended TIMS is shown in the Fig. , each showing a curve of velocity (or effective velocity component) as a function of position along the z-axis. As shown in Fig. As shown, there is an essentially constant gas velocity, v gas, which drives the ions through the ion region in the direction of the z-axis. This movement is controlled by a DC electric field -E DC (t), which has a spatial gradient along the z-axis, which has the effective velocity component -v shown in the figures DC (t) which ranges from zero to a maximum at the longitudinal position z p rises to a plateau, which, as explained below, may be an elution point for ions, where the ions are no longer stored in the laterally extended TIMS. The negative value of the DC electric field is due to its opposing direction to the force of the gas and is plotted against time, since in this embodiment, the strength of the DC electric field is reduced during the elution of the various ion species.

[0039] Fig. resembles Fig. , but shows the “effective” velocity component -v DC due to the opposing direct electric field for each of the different ion types K n-1 , K n and K n+1 In the presence of a gas, this “effective” velocity component is mobility-dependent and the corresponding -v DC -Gradient is therefore shown in the figure with dashed lines for the respective ion types K n-1 , K n and K n+1 These gradients represent the velocity components that are assigned to the different ion types by the DC electric field E DC (t) in the absence of gas flow v gas would be transferred. That is, -v DCis the velocity component attributable to the direct current electric field for an ion in a stationary gas at a given pressure and temperature. This value is proportional to the strength of the direct current electric field and is different for each ion type with different mobility K (where: v DC = K · E DC ). For all ion types K n-1 , K n and K n+1 In the absence of the DC electric field, the gas flow generates the “effective” velocity v gas .

[0040] The DC electric field gradient along the z-axis leads to a corresponding gradient for -v DC , which is different for ion types with different mobility, as in Fig. shown. During a first accumulation phase of the ions, the strength of the DC electric field is chosen so that the position at which - v DCequal to the opposite velocity component v caused by the gas flow gas is different for each of the ion types. Due to the different -v DC -Gradients of the different ion types separate the ions of the different ion types and store them at different positions along the z-axis. The different ion types, K n-1 , K n and K n+1 , are in Fig. represented by circles of different sizes, with the larger circles corresponding to ion types with a larger cross section and thus with lower mobility K.

[0041] After separation of the different ion types, the ions can be eluted one after the other from the laterally extended TIMS and directed into a downstream component of a hybrid IMS-MS system or into an ion detector. During elution, the DC electric field gradient is gradually reduced, thereby reducing the magnitudes of the v DC -Reduce velocity component gradients accordingly, as in Fig. As these gradients are reduced, the point at which the opposing velocity components v gas and -v DC compensate for the ion concentrations, shifted for each of the ion species in the +z direction, ie towards the exit of the laterally extended TIMS. The electric field is structured in such a way that the gradient increases in the +z direction until it reaches the elution point z pa plateau is reached along the z-axis. Since the position for storing the ions is different for each of the ion types, the shifting of these storage positions by lowering the DC electric field gradient leads to the individual ion types arriving at the elution point z at different times. p Once an ion species has reached the elution point, it is no longer held back by the opposing velocity component and leaves the laterally extended TIMS in the +z direction, as for the ion species K n-1 in Fig. This results in the separated ion species being eluted from the laterally extended TIMS one after the other, from low mobility to high mobility.

[0042] A second embodiment of a high-frequency device according to the invention is shown in the Fig. shown.

[0043] Fig. shows a radio-frequency device 200, which can also be part of a (laterally extended) storage ion mobility separator (TIMS). Like the radio-frequency device 100, the radio-frequency device 200 includes an upper electrode set 201 and a lower electrode set 202, each with electrodes 201-1 to 201-N and 202-1 to 202-N. The upper electrodes 201 engage the lower electrodes 202 along the z-direction, forming the ion region 210. As in the embodiment above, the cross-sectional profile of the ion region 210 is convex and does not vary along the longitudinal axis of the radio-frequency device.

[0044] Two different radiofrequency potentials (RF1, RF2) with different frequencies are used, with RF1 being applied to electrodes 201 and RF2 being applied to electrodes 202. Along the z-direction, electrodes 201 alternate with electrodes 202, and two antiphases are used for each of the radiofrequency potentials. A first phase of RF1 (RF1+) is applied to each odd-numbered upper electrode (201-1, 201-3, ...), while an antiphase RF1- (which has a phase difference of 180° with respect to RF1+) is applied to the even-numbered upper electrodes (201-2, 201-4, ...). Similarly, a first phase of RF2 (RF2+) is applied to each odd-numbered lower electrode (202-1, 202-3, ...), while an opposite phase, RF2-, is applied to the even-numbered lower electrodes (202-2, 202-4, ...). The radiofrequency potentials confine the ions in the ion field transversely in both the x- and y-directions.The ion region 210 has an elongated cross-sectional profile perpendicular to the z-direction with a long dimension in the y-direction and a short dimension in the x-direction.

[0045] As in the embodiment shown above, DC potentials are also applied to the upper and lower electrodes (201, 202) to generate a DC electric field gradient that provides one of the opposing forces of the laterally extended TIMS. The other opposing force can again be generated by a gas flow at a uniform velocity.

[0046] Fig. shows the first upper electrode 201-1 and the first lower electrode 202-1, both of which are significantly longer in the long dimension (y-direction) than in the short dimension (x-direction). The upper and lower electrodes partially overlap in the regions 220 at both ends of the long dimension.

[0047] The upper and lower electrodes (201, 202) are simplified compared to the upper and lower electrodes (101, 102) of the above embodiment. The upper and lower electrodes (201, 202) have a uniform thickness, which makes their manufacture easier and less expensive. The upper and lower electrodes (201, 202) can be manufactured directly as metallized parts of a printed circuit board or by laser cutting metal plates, arranging a plurality of circuit boards with electrodes or the metal plates as a stack along the axis. For example, the thickness can be between 0.3 and 1 mm. Preferably, the thickness is about 0.5 mm, and the distance between the upper (and lower) electrodes is about 2.5 mm.

[0048] Fig. shows the first upper electrode 201-1 and the first lower electrode 202-1 in the xy-plane. Both electrodes have a common contour at both (left and right) overlapping regions 220. As shown, the cross-sectional profile is oval and symmetrical with respect to the yz-plane. However, the cross-sectional profile can also be oval only near the overlapping regions 220 and still consist of a long parallel section in the center. The cross-sectional profile can also contain notches, making it non-convex. The electrode curvature of each set 201 and 202 is preferably the same, but can be different for the upper set 201 than for the lower set 202 (with the exception of the overlap region 220). The curvature of the upper and lower electrodes can even be irregular, i.e., the curvature can contain irregular notches.

[0049] Fig. shows an alternative configuration in which two electrodes (201-1', 202-1') of an upper set 201' and a lower set 202' each have a long parallel section near the center of the ion region and curved edges at the lateral ends. The two sets (201', 202') overlap in the regions 220' at both ends of the long dimension. Like the upper and lower electrodes (201, 202) in Fig. The electrodes of sets 201' and 202' are compared to those in Fig. reproduced upper and lower electrodes (101, 102). The upper and lower electrodes (201', 202') of the embodiment of Fig. have a uniform thickness, which makes their production easier and cheaper. The cross-sectional profile is rounded at both (left and right) overlapping areas 220' and contains a long parallel section in the middle. In contrast to the upper and lower electrodes (201, 202) of Fig. contain the upper and lower movements (201', 202') from Fig. additional electrodes 201-1" and 202-1". The additional electrode 201-1" bridges the gap of the upper electrode 201-1' between the overlapping regions 220'. The additional electrode 202-1" bridges the gap of the lower electrode 202-1' between the overlapping regions 220'. Two different radiofrequency potentials having different frequencies are applied to the electrodes of the upper set 201' and the lower set 202', as described above for the upper and lower electrodes (201, 202) of Fig. described. As in the embodiment shown above, DC potentials can be applied to the upper electrodes 201' and lower electrodes 202' to create a DC electric field gradient that provides one of the opposing forces of a laterally extended TIMS in which the electrodes can be used. No radio-frequency potentials are applied to the additional electrodes 201-1" and 202-1", but rather the same DC potentials of the electrode of the upper and lower sets (201-1', 202-1') that sits in the same xy plane and for which the additional electrode bridges the gap between the overlapping regions 220'. The additional electrodes 201-1" and 202-1" improve the homogeneity of the DC electric field gradient.

[0050] Fig. shows a schematic view of an ion region of a radio frequency device 200'' in both the yz-plane and the xy-plane at the input and output of the radio frequency device 200". The radio frequency device 200" is similar to the radio frequency device 200 of Fig. Similar, but the cross-sectional profile is not constant along the z-direction, but varies from an oval cross-sectional profile at the entrance to a circular cross-sectional profile at the exit. The extent of the ion area along the x-direction remains constant, while the extent along the y-direction decreases, resulting in a spatial focusing of the ions along the y-direction. However, the cross-sectional profile can also change in both transverse directions.

[0051] A third embodiment of a high-frequency device according to the invention is shown in the Fig. shown.

[0052] Fig. shows a radio-frequency device 300 including an upper set of electrodes 301, a lower set of electrodes 302, a left set of electrodes 303, and a right set of electrodes 304 arranged in a stack along the axis (z-direction) of the radio-frequency device 300. The radio-frequency device 300 has an ion region 310 having a rectangular cross-sectional profile perpendicular to the z-direction, extending slightly further in the y-direction than in the x-direction, and not varying along the longitudinal axis of the radio-frequency device 300.

[0053] The electrodes of the upper set 301 do not engage the electrodes of the lower set 302 along the z-direction, but the electrodes of the left and right sets (303, 304) engage between the electrodes of the upper and lower sets (301, 302).

[0054] The electrodes of the four sets are rod-shaped. The rod-shaped electrodes of the upper and lower sets (301, 302) extend parallel to the y-direction. The rod-shaped electrodes of the left and right sets (303, 304) extend parallel to the x-direction along the left and right edges of the ion region 310. The electrodes can be fabricated, for example, as metallized parts of a circuit board supplied with suitable radio-frequency and DC potentials, and a plurality of such circuit boards with electrodes can be arranged in a stack along the axis.

[0055] Fig. shows a schematic side view (xz plane) of the upper electrodes 301, the lower electrodes 302, and the right electrodes 304. Radiofrequency potentials (RF301, RF302) are applied to the electrodes of the upper and lower sets (301, 302), but not to the electrodes of the right set 304 and not to the electrodes of the left set 303 (not shown). As explained above, the electrodes of the upper set 301 do not engage the lower electrodes 302 along the z-direction, but the electrodes of the left and right sets (303, 304) are arranged between the electrodes of the upper and lower sets (301, 302). In contrast to the above embodiments, the electrode sets 301, 302 to which radiofrequency potentials are applied do not completely surround the ion region 310, but only the upper and lower boundaries of the ion region 310.

[0056] The first high-frequency potential (RF1) is applied to the upper electrodes 301 and the second high-frequency potential (RF2) is applied to the lower electrodes 302. As in Fig. As shown, two antiphases are used for each of the radiofrequency potentials. For example, a first phase of RF1 (RF1-) is applied to each odd-numbered upper electrode (301-1, 301-3, ...), while an antiphase RF1+ (which has a phase difference of 180° with respect to RF1-) is applied to the even-numbered upper electrodes (301-2, 301-4, ...). Similarly, a first phase of RF2 (RF2-) is applied to each odd-numbered lower electrode (302-1, 302-3, ...), while an antiphase, RF2+, is applied to the even-numbered lower electrodes (302-2, 302-4, ...). Ions are therefore confined by a pseudopotential in the ion region 310 only in the x-direction, but not (or only in a very limited way) along the y-direction.An important advantage of applying radiofrequency potentials of two different frequencies to the electrode structures of the two boundaries is that essentially no pseudopotential wells are formed along the longitudinal axis within the ion region.

[0057] Fig. shows a schematic side view (xz-plane) of the upper electrodes 301, the lower electrodes 302 and the right electrodes 304 of the embodiment of Fig. . DC potentials (DC304-1, ... DC304-N) are applied to the electrodes of the right set 304 and DC potentials (DC303-1, ... DC303-N) are applied to the electrodes of the left set 303 (not shown).

[0058] DC potentials (DC301-1 to DC301-N) and (DC302-1 to DC302-N) may also be applied to the upper and lower electrodes (301, 302) to actively conduct ions through the radio frequency device 300, to accelerate ions into or within the radio frequency device 300, or to store ions within the radio frequency device 300 along the axis.

[0059] The DC potentials (DC303, DC304) applied to the left and right electrodes (303, 304) are repulsive and are used to transversely confine the ions along the y-direction in the ion region 310. Preferably, the DC potentials applied to the left and right electrodes (303, 304) have an offset with respect to the DC potentials applied to their immediate upper and lower neighboring electrodes, so that ions are transversely confined along the y-direction, even if the DC potential at the upper and lower electrodes (301, 302) changes along the axis, for example, to drive or store ions. This offset can be constant or vary along the axis. The DC potential applied to the nth electrode of the right set 304 is preferably equal to the DC potential applied to the nth electrode of the left set 303.

[0060] The radio-frequency device 300 can be filled with a gas and used as a cell for fragmenting ions by collision-induced dissociation (CID). By applying a DC voltage between an upstream component (not shown) and electrodes at the input of the radio-frequency device 300, ions can be axially accelerated into the radio-frequency device 300 and fragmented by collisions with gas molecules within the radio-frequency device 300. The ions can also be accelerated within the radio-frequency device 300 by applying suitable DC potentials along the axis to the electrodes of the radio-frequency device 300.

[0061] The radio-frequency device 300 can also be used as a radio-frequency ion guide or radio-frequency ion trap. DC potentials can be applied to the electrodes (301 to 304) to drive ions introduced into the radio-frequency device 300 or generated within the radio-frequency device 300 through the radio-frequency device 300 to the exit, particularly when it is filled with a damping gas or used as a CID fragmentation cell. By applying suitable DC potentials to the electrodes of the radio-frequency device 300, ions introduced into the radio-frequency device 300 or generated in the radio-frequency device 300 can be stored in the radio-frequency device 300. The radio-frequency device 300 can also be used as an ion mobility separator, particularly as a storage ion mobility separator.

[0062] The DC potentials applied to the electrodes of the radio-frequency device 300 can be time-dependent to vary the fragmentation energy for CID or to change the velocity of the ions within the radio-frequency device 300 over time. The DC potentials can, for example, be transient DC potentials for generating a traveling wave within the radio-frequency device 300. The DC potentials applied to the electrodes 301, 302, 303, and 304 can be generated via a resistor chain or by individual DC power supplies.

[0063] Fig. shows a schematic view of an ion region of a radio frequency device 300' in both the yz-plane and the xy-plane at the input and output of the radio frequency device 300'. The radio frequency device 300' is the radio frequency device 300 in Fig. Similar, but the cross-sectional profile is not constant along the z-direction, but varies from a square cross-sectional profile at the entrance to a rectangular cross-sectional profile at the exit. The extent of the ion field along the y-direction remains constant, while the extent along the x-direction decreases, resulting in spatial focusing of the ions along the x-direction. The radiofrequency device 300' can be used as a DC / RF ion funnel. The cross-sectional profile can also change in both transverse directions.

[0064] A fourth embodiment of a high-frequency device according to the invention is shown in the Fig. shown.

[0065] Fig. shows a radio-frequency device 400 including an upper set of electrodes 401 (401a, 401b, 401c) and a lower set of electrodes 402 (402a, 402b, 402c) arranged in a stack along the axis (z-direction) of the radio-frequency device 400. The radio-frequency device 400 has an ion region 410 having a rectangular cross-sectional profile perpendicular to the z-direction, extending further in the y-direction than in the x-direction, and not varying along the longitudinal axis of the radio-frequency device 400.

[0066] The upper and lower sets (401, 402) each contain an elongated electrode set (401b, 402b) between a left electrode set (401a, 402a) and a right electrode set (401c, 402c). Each electrode of the two sets (401, 402) is segmented and contains an elongated electrode between two short extensions, all arranged in a line along the y-direction. In contrast to the above embodiments, the ion region 400 is not completely surrounded by the upper and lower sets (401, 402). The ion region 400 is limited along the x-direction by the upper and lower electrode sets (401, 402) and along the y-direction to the region of the elongated electrode sets (401b, 402b). The electrodes of the upper set (401a, 401b, 401c) are offset along the z-direction from the electrodes of the lower set (402a, 402b, 402c).

[0067] In this embodiment, the electrodes of the upper and lower sets (401, 402) are rod-shaped with a circular cross-section. In other embodiments, the cross-sectional shape of the electrodes of the two sets need not be circular. For example, the rod-shaped electrodes may have a rounded surface only on one side facing the ion region 410. The segments of an electrode may be simplified as three thin conductive plates or fabricated as metallized parts of a circuit board. The thin conductive plates and the circuit boards are then arranged in a stack along the axis.

[0068] Two different radiofrequency potentials with different frequencies are applied to the upper and lower elongated electrodes (401b, 402b). The first radiofrequency potential RF1 is applied to the upper elongated electrodes 401b, and the second radiofrequency potential RF2 is applied to the lower elongated electrodes 402b. A first phase of RF1 is applied to each odd-numbered elongated upper electrode, while an opposite phase is applied to the even-numbered elongated upper electrodes. Similarly, a first phase of RF2 is applied to each odd-numbered elongated lower electrode, while an opposite phase is applied to the even-numbered elongated lower electrodes. Ions are therefore confined by a pseudopotential in the ion region 410 only in the x-direction, but not in the y-direction. Preferably, the radiofrequency potential applied to the elongated segment of an electrode is also applied to its short extension segments.

[0069] An important advantage of applying radiofrequency potentials of two different frequencies to the elongated upper and lower electrodes (401b, 402b) is that essentially no pseudopotential wells are formed along the axis within the ion region.

[0070] DC potentials are applied to the left electrode sets (upper 401a, lower 402a) and the right electrode sets (upper 401c, lower 402c). DC potentials can also be applied to the elongated electrode sets (upper 401b, lower 402b) to actively conduct ions through the radiofrequency device 400, to accelerate ions into or within the radiofrequency device 400, or to store ions within the radiofrequency device 400 along the axis.

[0071] The DC potentials applied to the left and right electrode sets (401a, 402a, 401c, 402c) are repulsive and are used to confine the ions transversely along the y-direction in the ion region 410. Preferably, the DC potentials applied to the left and right electrode sets (401a, 402a, 401c, 402c) have an offset with respect to the DC potentials applied to their directly adjacent, elongated neighboring electrodes, such that ions are confined transversely along the y-direction even if the DC potential at the elongated electrode sets (401b, 402b) changes along the axis, for example, to drive or store ions along the axis. The offset can be constant or vary along the axis. The DC potentials applied to the n-th electrodes in the stack of the left and right sets (401a, 402a, 401c, 402c) are preferably equal.

[0072] The DC potentials applied to the electrodes of the radio-frequency device 400 can be time-dependent, for example, to vary the fragmentation energy for CID or to change the velocity of the ions within the radio-frequency device 400 over time. The DC potentials can, for example, be transient DC potentials for generating a traveling wave within the radio-frequency device 400. The DC potentials applied to the electrodes 401a, 402a, 401b, 402b, 401c, and 402c can be generated via a resistor chain or by individual DC power supplies.

[0073] The radio frequency device 400 can be used as a radio frequency ion guide device, a radio frequency ion trap, a fragmentation cell, an ion mobility separator, in particular as a storage ion mobility separator, or in an ion accelerator / reflector of a time-of-flight mass analyzer.

[0074] Fig. shows a schematic view of an ion region of a radio frequency device 400' in both the yz-plane and the xy-plane at the input and output of the radio frequency device 400'. The radio frequency device 400' is the radio frequency device 400 in Fig. Similar, but the cross-sectional profile is not constant along the z-direction, but varies from a more elongated cross-sectional profile at the entrance to a less elongated cross-sectional profile at the exit. The extent of the ion region along the x-direction remains constant, while the extent along the y-direction decreases, resulting in a spatial focusing of the ions along the y-direction. The radio-frequency device 400' can therefore be used as a DC / RF ion funnel. The cross-sectional profile can also change in both transverse directions.

[0075] A fifth embodiment of a high-frequency device according to the invention is shown in Fig. shown.

[0076] Fig. shows a radio-frequency device 500 including an outer set of ring electrodes 501 and an inner set of ring electrodes 502 arranged in a stack along the axis (z-direction) of the radio-frequency device 500. The ion region is defined as the volume between the coaxially aligned inner and outer electrodes (501, 502). The cross-sectional profile does not change along the longitudinal axis of the radio-frequency device 500. The outer electrodes 501 are offset from the inner electrodes 502 along the z-direction.

[0077] In this embodiment, the cross-sectional profile of each ring electrode of the inner and outer electrode sets (501, 502) is annular. In other embodiments, the cross-sectional profiles of the electrodes do not have to be annular. For example, the shape of the electrodes can be rounded only on one side facing the ion region. The electrodes of the outer set can also be in the form of conductive plates with a round opening, while the electrodes of the inner set can be in the form of round conductive plates. The electrodes of the inner and outer sets can also be metallized parts of a circuit board. The conductive plates and circuit boards can then be arranged in a stack along the axis.

[0078] Two different radio-frequency potentials with different frequencies are applied to the inner and outer electrodes (501, 502). The first radio-frequency potential RF1 is applied to the outer electrodes 501, and the second radio-frequency potential RF2 is applied to the inner electrodes 502. A first phase of RF1 is applied to each odd-numbered outer electrode, while an opposite phase is applied to the even-numbered outer electrodes. Similarly, a first phase of RF2 is applied to each odd-numbered inner electrode, while an opposite phase is applied to the even-numbered inner electrodes. Ions are therefore confined in the ion region by a pseudopotential between the inner and outer electrodes. As described in the above embodiments, DC potentials can be applied to the inner and outer electrodes (501, 502).

[0079] In contrast to the above embodiments, the cross-sectional profile of the ion region in the Fig. The embodiment shown is non-convex, meaning that for any two points within the cross-sectional profile of the ion region, not all points along a line segment between the two points also lie within the cross-sectional profile. The advantage of a non-convex cross-sectional profile is that it reduces the influence of one charged ion on another and increases the number of ions that can be stored.

[0080] The radio frequency device 500 can be used, for example, as a radio frequency ion guide device, a radio frequency ion trap, a fragmentation cell, an ion mobility separator, and in particular as a storage ion mobility separator.

[0081] Fig. shows a schematic view of an ion region of a radio frequency device 500' in both the yz-plane and the xy-plane at the input and output of the radio frequency device 500'. The radio frequency device 500' is the radio frequency device 500 in Fig. similar, but the cross-sectional profile is not constant along the z-direction but varies, so that the annular volume decreases in both transverse directions, creating a spatial focusing of the ions.

[0082] A sixth embodiment of a high-frequency device according to the invention is shown in Fig. shown.

[0083] Fig. shows a radio-frequency device 600 including an outer set of arcuate electrodes 601 and an inner set of arcuate electrodes 602 arranged in a stack along the axis (z-direction) of the radio-frequency device 600. The outer arcuate electrodes 601 are offset from the inner arcuate electrodes 602 in the z-direction. An electrode 603 extending parallel to the longitudinal axis of the radio-frequency device 600 is arranged at one end of the two arcuate electrode sets (601, 602), and an electrode 604 is arranged at the other end of the two arcuate electrode sets (601, 602). The ion region is defined as the volume between the coaxially aligned arcuate electrodes (601, 602), bounded by the axially extended electrodes 603 and 604. The cross-sectional profile of the ion region does not vary along the longitudinal axis of the radio-frequency device 600.

[0084] In this embodiment, the electrodes of the outer and inner sets (601, 602) are curved with a circular cross-section, although in an alternative embodiment, the cross-section of the electrodes may be rounded only on one side facing the ion region (e.g., with a semicircular cross-section). The electrodes of the outer and inner sets (601, 602) may be replaced by conductive plates or may be metallized parts of a circuit board. The conductive plates and circuit boards may then be arranged in a stack along the axis. The extended electrodes (603, 604) may be segmented and may also be metallized parts of the same circuit board as the inner and outer arcuate electrodes.

[0085] Two different radio-frequency potentials with different frequencies are applied to the outer and inner arcuate electrodes (601, 602). The first radio-frequency potential RF1 is applied to the outer electrodes 601, and the second radio-frequency potential RF2 is applied to the inner electrodes 602. A first phase of RF1 is applied to each odd-numbered arcuate outer electrode, while an opposite phase is applied to the even-numbered arcuate outer electrodes. Similarly, a first phase of RF2 is applied to each odd-numbered arcuate inner electrode, while an opposite phase is applied to the even-numbered arcuate inner electrodes. Repulsive DC potentials are applied to the extended electrodes (603, 604).Ions are confined within the ion region by a pseudopotential generated by the arcuate radiofrequency electrodes (601, 602) and by the DC potential applied to the extended electrodes (603, 604). As described in the above embodiments, DC potentials can also be applied to the arcuate electrodes (601, 602).

[0086] As with the Fig. In the embodiment shown, the cross-sectional profile of the ion region is non-convex. The advantage of a non-convex cross-sectional profile is that it reduces the influence of one charged ion on another and increases the number of ions that can be stored.

[0087] Fig. shows a schematic view of an ion region of a radio frequency device 600' in both the yz-plane and the xy-plane at the input and output of the radio frequency device 600'. The radio frequency device 600' is similar to the radio frequency device 600 of Fig. similar, but the cross-sectional profile is not constant along the z-direction, the device instead has an azimuthal angle of the arcuate volume that decreases along the longitudinal axis of the radio frequency device.

[0088] Fig. shows a schematic view of an ion region of another radio-frequency device 600'' in both the yz-plane and the xy-plane at the input and output of the radio-frequency device 600''. Here, the cross-sectional profile does not vary along the longitudinal axis of the radio-frequency device 600'' and it contains three arcuate sections of the same curvature, forming a serpentine line. The electrodes defining the upper and lower boundaries can be as in the embodiment of Fig. The ions are confined between the upper and lower boundaries by applying two radiofrequency potentials with different frequencies to the upper and lower electrodes. Additional electrodes are arranged at each end of the serpentine line, to which repulsive DC potentials can be applied, as in the embodiment of Fig. shown.

[0089] Fig. is a schematic diagram of a mass spectrometric system 700, wherein a radio frequency device according to the invention can be used in various components of the mass spectrometric system 700.

[0090] The mass spectrometric system 700 may include two ion sources (711, 721), an ion mobility separator 734, a transfer ion guide 741, a mass filter 751, a fragmentation cell 761, and a mass analyzer 770. The ion mobility separator 734 is preferably a storage ion mobility separator (TIMS), more preferably a laterally extended TIMS, as shown in the Fig. described. The TIMS separator 734 is preferably operated in a parallel accumulation mode, i.e., the ions are accumulated in an upstream ion trap 731 while simultaneously analyzing the pre-accumulated ions in the TIMS separator 734. The mass filter 751 is preferably a quadrupole mass filter. The mass analyzer 770 is preferably an orthogonal ion injection time-of-flight analyzer (OTOF-MS). A separation device (not shown), such as a liquid chromatography device or an electrophoresis device, may be coupled to the mass spectrometric system 700.

[0091] The chamber 710 is at atmospheric pressure and contains, for example, an electrospray ion source 711 (ESI). Other possible types of ion sources include thermal spray ionization, desorption ionization (e.g., ionization by matrix-assisted laser desorption / ionization (MALDI) or secondary ionization), chemical ionization (CI), photoionization (PI), electron impact ionization (EI), or gas discharge ionization. Ions generated in the (ESI) ion source 711 are introduced into a first vacuum chamber 720 via a transfer capillary 712 and deflected into an RF ion funnel 723 using a repulsive DC electrical potential applied to a deflection electrode 722. The transfer capillary is preferably a short, large-bore capillary with an inner diameter of 1 mm or more and a length of 180 mm or less.

[0092] The vacuum chamber 720 is preferably under an elevated pressure between 1,000 Pa and 3,000 Pa and preferably comprises an ESI ion source 721 operated at negative pressure. The ions generated by the negative pressure ESI source 721 are deflected into the radio-frequency ion funnel 723 by a repulsive DC electrical potential applied to the deflection electrode 722. An additional MALDI source can be arranged at the position of the deflection electrode 722. The ESI ion sources 711 and 721 as well as the additional MALDI source can be operated simultaneously or separately. The radio-frequency ion funnel 723 can, for example, be a radio-frequency device according to the invention, for example as in one of the Fig. The ions can be driven through the radio-frequency ion funnel 723, for example, by an axial DC field generated within the radio-frequency ion funnel 723 or by a gas flow toward the exit of the radio-frequency ion funnel 723.

[0093] The pressure in the vacuum chamber 730 is preferably kept lower than the pressure in the upstream chamber 710, for example, between 100 Pa and 1,000 Pa. A gas flow toward the exit of the radio-frequency ion funnel 723 can be generated by pumping gas from the chamber 720 through an opening between the two chambers (720, 730). Ions are passed from the chamber 720 through the opening between the two chambers into the ion trap 731. The ion trap 731 is preferably a radio-frequency device according to the invention, for example, as shown in the Fig. described. The cross-sectional profile as well as the length of the ion trap 731 are preferably adapted to the cross-sectional profile and length of the downstream ion mobility separator 734, especially when the ion mobility separator 734 is a laterally extended TIMS. As described above, ions can be stored in the ion trap 731 and then actively driven out of the ion trap by an axial DC field. A repulsive DC electric potential applied to a deflection electrode 732 deflects the ions released from or passed through the ion trap 731 into the radiofrequency ion funnel 733. An additional MALDI source can be arranged at the position of the deflection electrode 732.

[0094] The radiofrequency ion funnel 733 collects the ions released from the ion trap 731 or the ions generated by the additional MALDI source in the chamber 730 and directs them to the ion mobility separator 734. The ion mobility separator is preferably a laterally extended TIMS, as in Fig. described. Preferably, the two opposing forces of the laterally extended TIMS 734 are a gas flow directed toward the exit of the laterally extended TIMS 734 and a DC field gradient.

[0095] The gas flow in the laterally extended TIMS 734 is generated by pumping gas at the outlet of the laterally extended TIMS 734 through a pump port (not shown) and through an opening between the two chambers (730, 740).

[0096] During an accumulation phase, the two opposing forces are in equilibrium, such that an equilibrium point with zero velocity exists for each ion species of interest in the laterally extended TIMS 734. During a subsequent elution phase, the stored ion species are finally released from the laterally extended TIMS 734 by changing the DC field gradient, with the ion species in the laterally extended TIMS 734 eluting sequentially according to their mobility K. The relative change of the opposing axial forces can be progressive, so that ion species of increasing mobility K gradually leave the laterally extended TIMS 734.

[0097] The ions released from the laterally extended TIMS 734 enter the downstream chamber 740 and are guided by the radiofrequency ion guide device 741 into the even further downstream chamber 750, in which the mass filter 751 is located. The radiofrequency ion guide device 741 may, for example, be a radiofrequency device according to the invention, for example as shown in the Fig. shown. Chamber 740 serves as a pressure stage between the fine vacuum of the laterally extended TIMS 734 and the high vacuum in which the mass filter 751 operates. Ions are directed or selected in the mass filter 751 according to their mass.

[0098] The ions passing through mass filter 751 are then directed to a fragmentation cell 761 in chamber 760, where ions can be fragmented to enable mass spectrometric measurement of the ion fragments. In the exemplary embodiment, fragmentation is performed by collision-induced dissociation (CID). However, other common fragmentation methods can also be used, including but not limited to: infrared many-photon dissociation (IRMPD) or ultraviolet photodissociation (UVPD), surface-induced dissociation (SID), photodissociation (PD), electron capture dissociation (ECD), electron transfer dissociation (ETD), collisional activation after electron transfer dissociation (ETcD), activated ion-electron transfer dissociation (AI-ETD), or fragmentation by reactions with highly excited or radical neutrals.

[0099] The fragmentation cell 761 may, for example, contain a radio frequency device according to the invention, for example as shown in the Fig. described. CID fragmentation can be turned on or off by instrumental parameters, for example, by an axial accelerating voltage. Precursor ions can be stored in the fragmentation cell 761 without being fragmented. Fragment ions can also be stored there when fragmentation is turned on. DC potentials can be applied to the electrodes of the fragmentation cell 761 to generate an axial DC field for ejecting stored ions into the downstream mass analyzer 770, which can be one of several different types of mass analyzer.

[0100] In the exemplary embodiment, the mass analyzer 770 is a time-of-flight mass analyzer with orthogonal ion injection, as known in the art. Other suitable mass analyzers include an electrostatic ion trap, an RF ion trap, an ion cyclotron resonance ion trap, and a quadrupole mass filter. The time-of-flight mass analyzer 770 includes an accelerator 771, a flight path 772, a reflector 773, and an ion detector 774. The flight path 772 is preferably field-free. An additional reflector may be arranged between the accelerator 771 and the ion detector 774 so that the ions are doubly reflected in the reflector 773 and travel in W-shaped instead of V-shaped trajectories. The high-frequency device according to the invention can be incorporated into the accelerator 771, the flight path 772 and / or the reflector 773.

Claims

[1] A radio frequency device for transverse confinement of ions in an ion region, comprising: a first set of electrodes arranged parallel to one another and arranged one behind the other along a direction of ion movement to define a first transverse boundary of the ion region, and which are supplied with a first radio-frequency voltage such that opposite phases of the first radio-frequency voltage are applied to adjacent electrodes of the first set; and a second set of electrodes arranged parallel to each other and arranged one behind the other along the direction of ion movement to define a second transverse boundary of the ion region, and which are supplied with a second radio-frequency voltage so that opposite phases of the second radio-frequency voltage are applied to adjacent electrodes of the second set, wherein the first and second transverse boundaries are opposite each other in a transverse direction of the ion region and the first radio-frequency voltage and the second radio-frequency voltage have different frequencies, wherein the electrodes of the first set have a relative distance equal to a relative distance of the electrodes of the second set, characterized by , that the arrangement of the electrodes of the second set is offset relative to the electrodes of the first set along the direction of ion movement by a predetermined amount. [2] The high frequency device according to claim 1, characterized by that the first and second high-frequency voltages differ by more than 10%. [3] The high-frequency device according to one of claims 1 or 2, characterized bythat the electrodes of the respective first and second sets have a relative distance S along the direction of ion movement and the first and second transverse boundaries have a relative distance D from each other in the transverse direction, the ratio D:S being less than 10 in at least one section of the radio frequency device along the direction of ion movement. [4] The high-frequency device according to any one of claims 1 to 3, characterized by that the predetermined amount by which the arrangement of the electrodes of the second set is offset relative to the electrodes of the first set along the direction of ion movement is equal to half of said relative distance. [5] The high-frequency device according to any one of claims 1 to 4, characterized by that the electrodes of the first and second sets together enclose a cross-sectional profile of the ion region. [6] The high frequency device according to claim 5, characterized by that the electrodes of the first set engage at least partially in an overlapping region with the electrodes of the second set. [7] The high-frequency device according to any one of claims 1 to 4, characterized by that the electrodes of the first and second sets do not completely enclose the cross-sectional profile of the ion region, wherein additional electrodes or electrode segments are supplied with repulsive DC potentials in order to transversely confine the ions in partial regions of the ion region which are not adjacent to the electrodes of the first or second set. [8] The high frequency device according to claim 7, characterized bythat DC potentials are applied to electrodes of the first or second set, wherein the repulsive DC potentials applied to the additional electrodes or electrode segments have a DC offset relative to the DC potentials applied to adjacent electrodes of the first and second sets. [9] The high-frequency device according to any one of claims 1 to 8, characterized by that a plurality of electrodes of the first and / or second set have a rod-shaped section with a round cross-section. [10] The high frequency device according to claim 9, characterized by that a ratio of a diameter of the round cross-section to a distance between the adjacent rod-shaped sections is approximately two to three (2:3). [11] The high-frequency device according to any one of claims 1 to 10, characterized by that a cross-sectional profile of the ion region is convex. [12] The high-frequency device according to any one of claims 1 to 10, characterized by that a cross-sectional profile of the ion region is non-convex. [13] The high-frequency device according to any one of claims 1 to 12, characterized by that the ion region has an elongated cross-sectional profile perpendicular to the direction of ion motion with a long dimension and a short dimension. [14] The high-frequency device according to any one of claims 1 to 13, characterized by that a cross-sectional profile of the ion region varies along the direction of ion movement. [15] The high frequency device according to claim 14, characterized by that the cross-sectional profile at the input of the high-frequency device is larger than at its output. [16] The high-frequency device according to any one of claims 1 to 15, further comprising a DC voltage generator configured to apply repulsive DC voltage potentials to electrodes of the first and / or second set near an entrance and an exit of the ion region such that ions are temporarily stored in the ion region along the direction of ion movement. [17] The radio frequency device of any one of claims 1 to 15, further comprising a DC voltage generator configured to apply DC potentials to the electrodes of the first and / or second set in the direction of ion movement so that ions are driven through the ion region, accelerated within or into the ion region, or released from the ion region. [18] A mass spectrometric system comprising: an ion source; a mass analyzer; and a radio frequency device for transverse confinement of ions in an ion region, comprising: a first set of electrodes arranged parallel to one another and arranged one behind the other along a direction of ion movement to define a first boundary of the ion region, and which are supplied with a first radio-frequency voltage such that opposite phases of the first radio-frequency voltage are applied to adjacent electrodes of the first set; and a second set of electrodes arranged parallel to each other and arranged one behind the other along said direction of ion movement to define a second boundary of the ion region, and which are supplied with a second radio-frequency voltage so that opposite phases of the second radio-frequency voltage are applied to adjacent electrodes of the second set, wherein the first and second transverse boundaries are opposite each other in a transverse direction, the first high-frequency voltage and the second high-frequency voltage have different frequencies, wherein the electrodes of the first set have a relative distance equal to a relative distance of the electrodes of the second set, characterized by , that the arrangement of the electrodes of the second set is offset relative to the electrodes of the first set along the direction of ion movement by a predetermined amount. [19] The mass spectrometric system according to claim 18, characterized bythat the electrodes of the respective first and second sets have a relative distance S along the direction of ion movement and the first and second boundaries have a relative distance D from each other in the transverse direction, the ratio D:S being less than 10 in at least a portion of the radio frequency device along the direction of ion movement. [20] The mass spectrometric system of any one of claims 18 or 19, further comprising an ion mobility separator between the ion source and the mass analyzer, said ion mobility separator comprising the radio frequency device. [21] The mass spectrometric system according to claim 20, characterized by that the ion mobility separator further comprises a gas flow along the direction of ion movement and a DC voltage generator, wherein the DC voltage generator is configured to supply DC potentials to the electrodes of the first and second sets to generate a DC electric field gradient along the direction of ion movement that counteracts a force of the gas flow so that ions are stored during an accumulation phase and separated according to ion mobility, and wherein the DC voltage generator is configured to vary the DC potentials applied to the electrodes of the first and second sets such that ions are released from the ion mobility separator during an elution phase separately in time according to the ion mobility. [22] The mass spectrometric system according to claim 21, characterized by that the ion region has an elongated cross-sectional profile perpendicular to the direction of ion motion with a long dimension and a short dimension. [23] The mass spectrometric system of any one of claims 18 to 22, further comprising a fragmentation cell between the ion source and the mass analyzer, said fragmentation cell comprising the radio frequency device. [24] The mass spectrometric system according to claim 23, characterized by that the fragmentation cell is filled with a collision gas and further comprises a DC voltage generator configured to apply DC potentials to the electrodes of the first and / or second set so that ions are accelerated into a collision gas and the fragment ions resulting from collision-induced dissociation are driven through the ion region. [25] The mass spectrometric system according to any one of claims 18 to 24, characterized bythat the mass analyzer is a time-of-flight mass analyzer and comprises the radio frequency device which is part of at least one orthogonal ion injection accelerator, a field-free flight path or a reflector.

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