Ion mobility spectrometer and method for analyzing sample by ion mobility spectrometry

Abstract

The invention relates to an ion mobility spectrometer having at least a first drift chamber and a first switchable ion gate for the controlled transfer of ions into the first drift chamber, in which: the first ion gate is designed as a field-switching ion gate having at least a first counter electrode and a first injection electrode; wherein a first ionization chamber, into which ions to be analyzed by ion mobility spectrometry can be fed from an ionization source, is formed between the first counter electrode and the first injection electrode. The invention also relates to an ion mobility spectrometer having at least a first drift chamber and a first switchable ion gate for controlled transfer of ions into the first drift chamber, and a second drift chamber separate from the first drift chamber and a second switchable ion gate for controlled transfer of ions into the second drift chamber. The invention also relates to a method for analyzing a sample by ion mobility spectrometry by means of an ion mobility spectrometer, such as an ion mobility spectrometer of the aforementioned type, in which ions to be analyzed are generated from the sample and provided in an ionization chamber of the ion mobility spectrometer by means of an ionization source.

Description

[0001] This application is a divisional application of a patent application with application number 201980037014.1, application date April 3, 2019, and invention name “Ion mobility spectrometer and method for analyzing samples by ion mobility spectrometry”. Technical Field

[0002] The present invention generally relates to the field of ion mobility spectrometers and to a method for analyzing a sample by ion mobility spectrometry. In this case, the abbreviation IMS is used both for the measuring method "ion mobility spectrometry" and for the measuring device "ion mobility spectrometer".

[0003] The present invention relates to an ion mobility spectrometer, which comprises at least a first drift chamber and a first switchable ion gate for controlled transfer of ions into the first drift chamber, wherein the first ion gate is embodied as a field switching ion gate comprising at least a first counter electrode and a first injection electrode, wherein a first ionization chamber is formed between the first counter electrode and the first injection electrode, and ionization chamber ions to be analyzed by ion mobility spectrometry can be fed into the first ionization chamber from an ionization source.

[0004] The invention also relates to an ion mobility spectrometer comprising at least a first drift chamber and a first switchable ion gate for controlled transfer of ions into the first drift chamber, and a second drift chamber separate from the first drift chamber and a second switchable ion gate for controlled transfer of ions into the second drift chamber.

[0005] The invention further relates to a method for analyzing a sample by ion mobility spectrometry by means of an ion mobility spectrometer, for example of the type described above, wherein ions to be analyzed are generated from the sample by means of an ionization source and provided in an ionization chamber of the ion mobility spectrometer. Background Art

[0006] Devices and methods for ion mobility spectrometry are known, for example, from DE 10 2015 112 869 A1 or EP 2 428 797 A1. Summary of the invention

[0007] The invention is based on the object of improving such an ion mobility spectrometer and a method for ion mobility spectrometry in terms of practical applicability.

[0008] The object is achieved by means of an ion mobility spectrometer, the ion mobility spectrometer comprising at least a first drift chamber and a first switchable ion gate for controlled transfer of ions into the first drift chamber, wherein the first ion gate is implemented as a field switching ion gate comprising at least a first counter electrode and a first injection electrode, wherein a first ionization chamber is formed between the first counter electrode and the first injection electrode, ionization chamber ions to be analyzed by ion mobility spectrometry can be fed from an ionization source into the first ionization chamber, wherein at least one first additional electrode is arranged between the first ion gate and the first drift chamber, and ions to be transferred into the first drift chamber by means of the first ion gate can additionally be influenced by the first additional electrode. With the additional presence of the first additional electrode (which does not originally exist in the ion mobility spectrometer with field switching ion gate), it is possible to realize a variety of extended functions of the ion mobility spectrometer, which enable the resolution and sensitivity of the ion mobility spectrometer to be improved. By generating a corresponding potential gradient between the electrodes, the first additional electrode can be able to realize, for example, a dual field switching method, an extended field switching method and a combination thereof, which are also described below, which are referred to as extended dual field switching methods. The outlay for realizing such an ion mobility spectrometer is relatively low, in particular because a field-switching ion gate can be used. Thus, the ion mobility spectrometer can be realized in a particularly compact and cost-effective manner in terms of its construction.

[0009] The field-switched ion gate comprises a counter electrode and an injection electrode. When a field-switched ion gate is used, ionization, i.e. the provision of ions from a sample, is achieved in a space without an electric field or with almost no electric field, which is also referred to as an ionization chamber. The ionization chamber is located between the counter electrode and the injection electrode, wherein the drift chamber of the ion mobility spectrometer is located behind the injection electrode as viewed from the ionization chamber. By means of a corresponding potential switching of the electrodes of the field-switched ion gate, the ions provided as ion packets in the ionization chamber can be transferred to the drift chamber, where they are guided by the electric field generated there along the ionization chamber as far as the ion detector, where the collision ions are detected. An ion mobility spectrometer of this design can be realized in a particularly compact and cost-effective manner in its structure, since in this case, an additional reaction chamber, such as known from DE 10 2015 112 869 A1, does not need to be arranged upstream of the drift chamber. Therefore, the ion mobility spectrometer can be embodied such that the electric field is generated in the ionization chamber only by the electrodes of the field-switching ion gate, so that no additional field generating means for generating the electric field in the ionization chamber is required.

[0010] The invention is based on the field switching principle for feeding ions from a corresponding ionization chamber into a corresponding drift chamber of an ion mobility spectrometer. The term "field switching" or "field switching ion gate" includes the following functions: the provision of ions to be analyzed, i.e. the ionization of analyte molecules, is achieved in an ionization space without an electric field or at least almost without an electric field, so that during this ionization phase, the provided ions have not yet moved in any direction due to the absence of an electric field. If an analysis step is subsequently intended, the electrodes of the field switching ion gate are switched accordingly, i.e. at least one electrode is switched, so that the ions are moved in the direction of the drift chamber.

[0011] Therefore, in the case of a field-switched ion gate, at least during the ionization phase, the ionization chamber is substantially free of an electric field. In order to achieve this state of no electric field in the ionization chamber, the same potential may exist between the counter electrode and the injection electrode of the field-switched ion gate. A small potential difference may also be applied between the counter electrode and the injection electrode to compensate for the field punch-through of the electric field from the drift chamber. However, in this case, the potential difference between the counter electrode and the injection electrode happens not to generate an electric field in the ionization chamber, but rather to offset the punch-through of the electric field of the drift chamber, and thus compensate for the state of the ionization chamber in the direction of the no electric field state.

[0012] The ion mobility spectrometer may comprise one first additional electrode or a plurality of first additional electrodes. Due to the presence of a plurality of first additional electrodes, the advantageous method steps described may also be performed in a variety of ways, for example in this case the compression of ion packets by double field switching may be performed as multi-field switching.

[0013] According to an advantageous development of the invention, the first additional electrode is arranged at the end of the first drift chamber facing the first ion gate. In this way, the ion mobility spectrometer can be further optimized in terms of structural dimensions. In addition, the first additional electrode can perform its desired function, for example for particularly effective shielding of the electric field in the drift chamber.

[0014] According to an advantageous development of the invention, the distance between the first additional electrode and the first injection electrode is smaller than the distance between the first counter electrode and the first injection electrode. In this way, the structural dimensions of the ion mobility spectrometer and the effectiveness of the first additional electrode can also be further increased. Thus, for example, the ion packets can be compressed particularly effectively in the second compression step, which is also described below.

[0015] According to an advantageous improvement of the invention, the first additional electrode is embodied in a potential non-switchable manner. Thus, the structure of the circuit hardware required for the operation of the ion mobility spectrometer is kept simple and the shielding effect is improved. For example, the ion mobility spectrometer can be embodied in a manner that the potential switching is achieved only at the first injection electrode.

[0016] The objects mentioned in the introduction are further achieved by means of an ion mobility spectrometer comprising at least a first drift chamber and a first switchable ion gate for controlled transfer of ions into the first drift chamber, and a second drift chamber separated from the first drift chamber and a second switchable ion gate for controlled transfer of ions into the second drift chamber, wherein the first ion gate and / or the second ion gate are embodied as field-switched ion gates. In this way, for example, an ion mobility spectrometer with bipolarity can be realized due to the fact that the part comprising the first drift chamber is configured for analyzing positive ions and the part comprising the second drift chamber is configured for analyzing negative ions. The realization of such an ion mobility spectrometer with one or two ion gates as field-switched ion gates enables a particularly compact structure to be realized during the measurement while having ultrahigh resolution capability and extremely high sensitivity.

[0017] According to an advantageous improvement of the present invention, the first ion gate comprises at least a first counter electrode and a first injection electrode, wherein a first ionization chamber is formed between the first counter electrode and the first injection electrode, and ions to be analyzed by ion mobility spectrometry can be fed from an ionization source into the ionization chamber. Therefore, in this case, the first ion gate is configured as a field switching ion gate. Here, similar to the previous description, the first injection electrode can be arranged closer to the first drift chamber than the first counter electrode.

[0018] According to an advantageous improvement of the present invention, the second ion gate comprises at least a second counter electrode and a second injection electrode, wherein a second ionization chamber is formed between the second counter electrode and the second injection electrode, and ions to be analyzed by ion mobility spectrometry can be fed from an ionization source into the ionization chamber. In this case, the second ion gate is configured as a field switching ion gate. Here, the second injection electrode can be arranged closer to the second drift chamber than the second counter electrode.

[0019] At the end of the first drift chamber away from the first injection electrode, the ion mobility spectrometer may include a first detector for detecting a first ion species, such as positive ions. At the end of the second drift chamber away from the second injection electrode, the ion mobility spectrometer may include a second detector for detecting a second ion species, such as negative ions.

[0020] The first ionization chamber formed between the first counter electrode and the first injection electrode can be connected to the second ionization chamber formed between the second counter electrode and the second injection electrode, or can be implemented as a common ionization chamber. Independently of this, but also in combination with these features, the ion mobility spectrometer can be embodied by a common ionization source, which provides ions of two polarities in the corresponding ionization chambers or the common ionization chamber.

[0021] According to an advantageous improvement of the present invention, the first ion gate and the second ion gate are formed by the arrangement of at least a first multifunctional electrode and a second multifunctional electrode, wherein the first multifunctional electrode is arranged upstream of the first drift chamber, and the second multifunctional electrode is arranged upstream of the second drift chamber, wherein the first multifunctional electrode forms the injection electrode of the first ion gate, and the second multifunctional electrode forms the counter electrode of the first ion gate, and the second multifunctional electrode forms the injection electrode of the second ion gate, and the first multifunctional electrode forms the counter electrode of the second ion gate. Therefore, a particularly simple structure of the ion gate can be achieved. Then a common ionization chamber including the first ionization chamber and the second ionization chamber can be formed between the multifunctional electrodes.

[0022] In the embodiment with multifunctional electrode described above, a pure counter electrode that performs only the function of a counter electrode can be omitted. Therefore, a simpler structure of an ion mobility spectrometer with two ion gates can be achieved, which requires fewer electrodes. A common ionization chamber that achieves higher positive and negative ion yields is also advantageous. In order to perform the extended field switching and extended dual field switching methods also described below, it is advantageous to provide two first additional electrodes and two second additional electrodes in different situations. In this case, the additional electrode positioned closest to the corresponding drift chamber can be maintained at a fixed potential; other additional electrodes arranged closer to the multifunctional electrode can be switched to different potentials.

[0023] The ion mobility spectrometer can be realized in such a way that the first drift chamber and the second drift chamber are arranged one behind the other on the same or at least substantially parallel axes. This enables a relatively long structural length and a small diameter of the ion mobility spectrometer.

[0024] According to an advantageous improved form of the present invention, the first drift chamber and the second drift chamber are arranged substantially parallel to each other. Therefore, the structural size of the ion migration spectrometer can be further reduced. Specifically, compared with the embodiment described above, the structural length is substantially halved. In the case of this design, the arrangement of the electrodes of the corresponding ion gates can be interchanged, that is, in this case, the first counter electrode can be arranged closer to the first drift chamber than the first injection electrode, and the second counter electrode can be arranged closer to the second drift chamber than the second injection electrode.

[0025] According to an advantageous improved form of the present invention, the first counter electrode and the second counter electrode are short-circuited to each other or are implemented as a common counter electrode. Therefore, the structure of the ion migration spectrometer can be further optimized with respect to both the structural size and the required components. In addition, the electrical structure can be further simplified. This embodiment is suitable, for example, for an ion migration spectrometer, in which the first drift chamber and the second drift chamber are arranged one after another on the same or at least substantially parallel axes. Alternatively, it can also be provided that the first injection electrode and the second injection electrode are short-circuited to each other or are implemented as a common injection electrode. For example, if the first drift chamber and the second drift chamber are arranged substantially parallel to each other, this is advantageous.

[0026] According to an advantageous development of the invention:

[0027] a) at least one first additional electrode is arranged between the first ion gate and the first drift chamber, the ions to be transferred into the first drift chamber by means of the first ion gate additionally being able to be influenced by the first additional electrode,

[0028] and / or

[0029] b) At least one second additional electrode is arranged between the second ion gate and the second drift chamber, the ions to be transferred into the second drift chamber by means of the second ion gate additionally being able to be influenced by the second additional electrode.

[0030] Thus, one or more first additional electrodes and / or one or more second additional electrodes may be present. The number of first additional electrodes and second additional electrodes respectively present may be different, ie the ion mobility spectrometer may also be embodied asymmetrically in that a single IMS tube is equipped with additional electrodes.

[0031] According to an advantageous development of the invention, the first additional electrode and / or the second additional electrode is embodied in a potential-switchable manner. This is particularly advantageous if extended field switching is intended. Thus, if the detector potential or gradient in the drift chamber is adapted to the situation of extended field switching, the potential of the corresponding additional electrode can be adapted.

[0032] According to an advantageous development of the invention, the ion mobility spectrometer comprises as ionization source an X-ray ionization source, an ultraviolet (UV) ionization source, a corona ionization source, a plasma ionization source, a dielectric barrier discharge source and / or an electron emitter. In this way, in particular in connection with a field-switched ion gate, the above-mentioned high sensitivity and resolving power can be further improved.

[0033] The ionization source can be arranged, for example, laterally next to the corresponding ionization chamber. In this case, it is advantageous to use an ionization source with a large penetration depth or at least a large aperture angle. It is also possible to combine the ionization source with the counter electrode (first counter electrode and / or second counter electrode), for example by integrating the ionization source structure into the counter electrode or in an embodiment as the counter electrode of the ionization source.

[0034] The ionization source may be a non-radioactive ionization source or a radioactive ionization source. For example, the counter electrode may be coated with a radioactive material.

[0035] As far as a general explanation is given about the field-switched ion gate and its counter-electrode and injection electrode, this applies both to the first ion gate and to the second ion gate, that is to say to the first and second counter-electrodes as well as to the first and second injection electrodes. The above-described embodiments of the ion mobility spectrometer with a first additional electrode can be advantageously combined in the case of an ion mobility spectrometer with unipolarity (with only one drift chamber) and in the case of the described embodiments with a first drift chamber and a second drift chamber. In the last-mentioned case, the second additional electrode can then be arranged upstream of the second drift chamber.

[0036] The objects mentioned in the foregoing are further achieved by means of a method for analyzing a sample by ion mobility spectrometry by means of an ion mobility spectrometer of the aforementioned type, wherein ions to be analyzed are generated from the sample by means of an ionization source and provided in a first ionization chamber, and the ions generated in the process are guided through a first drift chamber to a first ion detector under the control of a first ion gate, wherein the first ionization chamber is substantially field-free at least in the ion generation period, characterized by one or both of the following features a), b):

[0037] a) before the ion packets are transferred into the first drift chamber, the ion packets provided in the first ionization chamber are compressed for a first time in a first compression step by switching the potential difference between the first injection electrode and the first counter electrode, and after passing the first injection electrode, the ion packets are compressed for a second time in at least a second compression step by switching the potential difference between the first additional electrode and the first injection electrode,

[0038] b) At least during the ion generation period, ions generated in the first ionization chamber are substantially shielded from the electric field portion generated in the first drift chamber by the first additional electrode or at least the additional shielding electrode.

[0039] In this way, advantageous methods of double field switching or multi-field switching (feature a)), extended field switching (feature b)) or extended double field switching (combination of features a) and b) in a combined manner can be implemented. With the aid of these methods, the resolving power of the ion mobility spectrometer can be increased without the need for an extension of the drift chamber (which is otherwise required). It is also possible to construct an ion mobility spectrometer with comparable resolving power, i.e. with a shorter drift chamber, in a more compact manner.

[0040] Due to the ionization by means of an ionization source, the ions to be analyzed are provided in a first ionization chamber. These ions provided are also referred to as ion packets. By means of the switching of an ion gate, i.e., for example, the electrodes of a field-switched ion gate, the ions of the ion packet move in the direction of the drift chamber and are compressed for the first time in the process. In this case, the term "compression" relates to the range of the ion packet in the desired flight direction, i.e., the range in the drift direction through the drift chamber. Due to the compression of the ion packet, the ion packet becomes narrower, which leads to an enhanced resolution of the ion mobility spectrum. By using a first additional electrode in a second compression step to perform further (second) compression of the ion packet, the ion packet can be narrower when transferred to the drift chamber compared to the ion mobility spectrometry method of the prior art. The second compression step may be followed by one or more other compression steps (multi-field switching) to make the ion packet narrower. However, in many cases, the second compression step will be sufficient for practical applications.

[0041] The first compression step can be achieved by generating an electric field in the ionization chamber by means of the ion gate, i.e. by generating a potential difference between the injection electrode and the counter electrode. The second compression step can be achieved by generating another electric field between the ionization chamber and the drift chamber. For this purpose, for example, a potential difference can be generated between the injection electrode and the additional electrode.

[0042] In the case of an ion mobility spectrometer of the above type, in particular when a field switching ion gate is used, more particularly when the injection electrode is arranged very close to the drift chamber (which is of course desirable) to achieve a small structural size, field penetration of the electric field present in the drift chamber into the ionization chamber may occur. In some cases, ions in the influence area of ​​the field penetration may have entered the drift chamber, which leads to a certain transmittance of the ion gate even in the closed state. Therefore, a small amount of leakage current entering the drift chamber may occur, which may lead to a significant reduction in the sensitivity and selectivity of the ion mobility spectrometer. In order to counteract this effect, it is conceivable to generate a very low electric field in the ionization chamber opposite to the field of the drift chamber, for example by applying a so-called blocking voltage to the counter electrode. However, this has the effect of moving the ions in the ionization chamber in the direction of the counter electrode, which does prevent the ions from passing through the closed ion gate to a certain extent, but leads to ion losses at the counter electrode. This also reduces the sensitivity of the ion mobility spectrometer. In addition, other distinctions of specific ion species may occur. This can be prevented by the extended field switching method according to the present invention, in particular by shielding of the ions generated in the ionization chamber by shielding of the first additional electrode or at least the additional shielding electrode. The first additional electrode or shielding electrode is then arranged behind the first injection electrode as viewed from the ionization chamber. In this way, the ionization chamber can still be operated essentially without an electric field as long as the ion gate is closed. However, since the area through which the field is passed is shielded by the ionization chamber, undesired ions are prevented from passing through the closed ion gate. Thus, by this method, the sensitivity and selectivity of the ion mobility spectrometer can be increased in a simple manner and undesired discrimination of specific ion species can be avoided.

[0043] The objects mentioned in the foregoing are further achieved by means of a method for analyzing a sample by ion mobility spectrometry, wherein by means of an ionization source, ions to be analyzed are generated from the sample and provided in a first ionization chamber and / or a second ionization chamber, and the positive and negative ions generated in the process are guided to separate respective ion detectors through separate drift chambers under the control of respective first and second ionization gates, wherein the first ionization chamber and / or the second ionization chamber are substantially free of an electric field at least during the ion generation period. By means of this method, the advantages associated with field-switched ion gates can also be achieved.

[0044] The method that has been described can be used in any of the embodiments of the ion mobility spectrometer described above.

[0045] According to an advantageous development of the invention, the first counter electrode and the second counter electrode have the same potential. Thus, the circuit structure for driving the ion gate and the structure of the ion gate itself are simplified.

[0046] According to an advantageous improved form of the present invention, the opening and closing of the first ion gate and / or the second ion gate is realized by the potential switching of the injection electrode and / or the counter electrode of the corresponding ion gate. By this method, the electric drive of the ion gate is also simplified. Further potential switching at other electrodes or at multiple electrodes can be avoided.

[0047] According to an advantageous development of the invention, in the first compression step, the potential gradient between the first counter electrode and the first injection electrode is greater than the potential gradient in the drift chamber. Thus, effective compression of the ion packets in the first compression step can be achieved.

[0048] According to an advantageous development of the invention, in the second compression step, the potential gradient between the first injection electrode and the first additional electrode is greater than the potential gradient in the drift chamber. Thus, effective compression of the ion packets in the second compression step can be achieved.

[0049] According to an advantageous development of the invention, the potential gradient between the first injection electrode and the first additional electrode is greater in the second compression step than in the first compression step. Thus, a particularly large compression of the ion packets in the second compression step can be achieved.

[0050] According to an advantageous development of the invention, in the first compression step, the potential gradient between the first injection electrode and the first additional electrode is substantially equal to the potential gradient of the drift chamber. In this way, a uniform transfer of ion packets from the ion gate into the drift chamber can be achieved.

[0051] According to an advantageous development of the invention, in the first compression step, the potential gradient between the first injection electrode and the first additional electrode is greater than the potential gradient between the first counter electrode and the first injection electrode and greater than the potential gradient of the drift chamber. In this way, ion focusing can be advantageously achieved, which can be used, for example, in extended field switching.

[0052] According to an advantageous development of the invention, the potential gradient between the first injection electrode and the electrode for shielding (i.e. the first additional electrode or shielding electrode) is equal to zero or at least opposite to the potential gradient in the drift chamber during the ion generation period. In this way, a good shielding effect can be achieved in extended field switching without appreciable ion losses.

[0053] According to an advantageous development of the invention, when switching to the first compression step, the potential gradient between the first injection electrode and the first additional electrode is switched later than the potential gradient between the first counter electrode and the first injection electrode. In this way, undesirable fast ions can be eliminated.

[0054] According to an advantageous development of the invention, when leaving the first compression step, i.e., when changing to the second compression step, the potential gradient between the first counter electrode and the first injection electrode is switched earlier than the potential gradient between the first injection electrode and the first additional electrode. In this way, undesirable slow ions can be eliminated.

[0055] In this case, a potential gradient is understood to mean the gradient of the potential in the direction of the longitudinal axis of the drift chamber or in the desired drift direction of the ions in the drift chamber.

[0056] In the case of an ion mobility spectrometer with a second drift chamber, for example in the bipolar case, the features mentioned above with respect to the first ion gate, the first counter electrode, the first injection electrode, the first additional electrode and the first drift chamber can also be used as advantageous improved forms of the corresponding components of the second ion gate, i.e. the second counter electrode, the second injection electrode and the second additional electrode and / or the second drift chamber. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The present invention is explained in more detail below based on exemplary embodiments using the drawings.

[0058] In the attached picture:

[0059] Figure 1 An ion mobility spectrometer having two drift chambers is shown;

[0060] Figure 2 Another embodiment of an ion mobility spectrometer having two drift chambers is shown;

[0061] Figure 3 An ion mobility spectrometer having a drift chamber is shown;

[0062] Figure 4 shows that during double field switching, Figure 3 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0063] Figure 5 shows that during extended field switching, Figure 3 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0064] Figure 6 shows that during the extended double field switching period Figure 3 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0065] Figure 7 Another embodiment of an ion spectrometer having two drift chambers is shown;

[0066] Figure 8 Another embodiment of an ion mobility spectrometer having two drift chambers is shown; Fig. 9Shows the normal field or double field switching period according to Figure 8 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0067] Fig.10 An embodiment of an ion mobility spectrometer having two drift chambers and two multifunctional electrodes is shown;

[0068] Fig.11 , Fig.12 Show according to Fig.10 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0069] Fig.13 An ion mobility spectrometer having two drift chambers is shown;

[0070] Fig.14 , Fig.15 shows that during extended field switching, Fig.13 An exemplary potential distribution diagram in an ion mobility spectrometer of Fig.16 An ion mobility spectrometer having two drift chambers in one embodiment is shown;

[0071] Fig.17 Show according to Fig.16 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0072] Fig.18 shows an ion mobility spectrometer having two drift chambers in a parallel arrangement; Figures 19 to 22 Show according to Fig.18 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0073] Fig.23 Another embodiment of an ion mobility spectrometer having two drift chambers in a parallel arrangement is shown; Figure 24 to Figure 27 Show according to Fig.23 An exemplary potential distribution diagram in an ion mobility spectrometer of

[0074] Fig.28 Another embodiment of an ion mobility spectrometer having two drift chambers in a parallel arrangement is shown; and Figure 29 to Figure 32 Show according to Fig.28 An exemplary potential profile in an ion mobility spectrometer. DETAILED DESCRIPTION

[0075] Figure 1An ion mobility spectrometer 1, 2 having a substantially coaxial arrangement of two IMS tubes 1, 2 is shown. The IMS tube 1 comprises a first ion gate 10, which comprises a first counter electrode 11 and a first injection electrode 12. A first ionization chamber 13 is formed between the first injection electrode 12 and the first counter electrode 11. Behind the first injection electrode 12, a first drift chamber 14 is adjacent to the first ionization chamber 13 and ends at a first ion detector 16. In the region of the first drift chamber 14, there is a first field generating device 15, for example in the form of an annular electrode surrounding the first drift chamber 14. The first field generating device 15 can generate an electric field in the first drift chamber 14, which exerts a desired drift effect on the ions to be examined, so that the ions are transmitted from the first ion gate 10 to the first ion detector 16. A drift gas can flow through the first drift chamber 14, for example in a direction opposite to the drift direction of the ions. To this end, the first IMS tube 1 comprises a first drift gas inlet connection 17 and a first drift gas outlet connection 18. The drift gas may be introduced into the IMS tube 1 at a first drift gas inlet connection 17. The drift gas may be discharged from the IMS tube 1 at a first drift gas outlet connection 18.

[0076] The ion mobility spectrometer or the first IMS tube 1 and the second IMS tube 2 may comprise additional connections for introducing and discharging the sample gas. These connections may be arranged, for example, in the region of the first ionization chamber 13 and / or the second ionization chamber 23 .

[0077] The second IMS tube 2 is constructed in a similar manner to the first IMS tube 1, but is arranged mirror-symmetrically with respect thereto. The second IMS tube 2 includes a second ion gate 20 having a second counter electrode 21 and a second injection electrode 22, wherein a second ionization chamber 23 is formed between the second injection electrode 22 and the second counter electrode 21. Other components of the second IMS tube 2 are a second drift chamber 24, a second field generating device 25, a second ion detector 26, a second drift gas inlet connector 27 and a second drift gas outlet connector 28. The corresponding elements of the second IMS tube 2 have the same functions as those described above for the components of the first IMS tube 1. For example, the first IMS tube 1 can be used to analyze positive ions, and the second IMS tube 2 is used to analyze negative ions.

[0078] In this case, the first counter electrode 11 and the second counter electrode 21 may also be embodied as a common counter electrode or electrically interconnected counter electrodes.

[0079] The ion mobility spectrometer further comprises an ionization source 3 providing ions in the first ionization chamber 13 and the second ionization chamber 23. The first ion gate 10 and the second ion gate 20 are each implemented as a field switching ion gate.

[0080] Figure 2An advantageous embodiment of an ion mobility spectrometer is shown, which also comprises a first IMS tube 1 and a second IMS tube 2, and the remaining parts include those already described with reference to Figure 1 Parts of the description. Figure 1 In contrast to the embodiment of Figure 2 In the embodiment, the IMS tubes 1, 2 are arranged substantially parallel to each other, thus resulting in a shorter structural length of the arrangement. In this case, it is possible to form a common ionization chamber made of a first ionization chamber 13 and a second ionization chamber 23, which is formed as in Figure 1 As in the embodiment of FIG. 5 , ions are supplied from a common ionization source 3 .

[0081] In accordance with Figure 2 In the embodiment of the present invention, the first ion gate 10 and the second ion gate 20 can each be connected with Figure 1 The embodiments are constructed in the same manner, ie such that the respective injection electrode is arranged closer to the drift chamber facing the ion gate than the respective counter electrode. Figure 2 A modified arrangement in this regard is shown, in which the positions of the injection electrodes and counter electrodes of the corresponding ion gates 10, 20 are interchanged. Obviously, the first injection electrode 12 is further away from the first drift chamber 14, and the first counter electrode 11 is arranged closer to the first drift chamber 14. In a similar manner, the second injection electrode 22 is further away from the second drift chamber 24, and the second counter electrode 21 is closer to the second drift chamber 24. This allows the first counter electrode 11 and the second counter electrode 21 to be implemented as a common counter electrode or at least as an electrically interconnected counter electrode. This simplifies the construction of the ion mobility spectrometer and the circuit construction required for the electrical operation of the ion mobility spectrometer.

[0082] Figure 3 An ion mobility spectrometer having only one IMS tube 1 is shown. Figure 1 The first IMS tube 1 of the embodiment is of a comparable construction, specifically, wherein the components of the first ion gate 10 include a first counter electrode 11 and a first injection electrode 12, a first ionization chamber 13 is formed between the first counter electrode 11 and the first injection electrode 12, and a first drift chamber 14 is adjacent to the first ion gate 10, and a first field generating device 15 is arranged in the region of the first drift chamber. A first ion detector 16 is arranged at the end of the first drift chamber 14. In addition, there is a first drift gas inlet connector 17 and a first drift gas outlet connector 18.

[0083] As an additional component, according to Figure 3The ion migration spectrometer comprises an additional electrode 19, which is arranged behind the first injection electrode 12, for example at the beginning of the first drift chamber 14, as viewed from the first counter electrode 11. The first additional electrode 19 can be implemented, for example, as a ring electrode or a gate, similar to the first injection electrode 12 or the first counter electrode 11. By applying a suitable potential to the first additional electrode 19 and by switching at least one other potential of the first ion gate 10, for example the potential at the first injection electrode 12, methods for dual field switching, for extended field switching and for extended dual field switching can be implemented. Reference is made below to Figures 4 to 6 This is illustrated in the timing diagram in .

[0084] Figures 4 to 6 The potential difference U is shown relative to the longitudinal extent s of the IMS tube 1. The potential difference U is the corresponding potential difference relative to the first ion detector 16. The positions of the first counter electrode 11, the first injection electrode 12, the first additional electrode 19 and the first ion detector 16 are indicated by vertical lines. Figures 4 to 6 In all examples of FIG. 1 , it is assumed that a linear potential profile with a relatively low potential gradient D and thus a low field strength of the electric field is present in the first drift chamber 14 .

[0085] Figure 4 An example of double field switching is shown. In this case, the potential of the first injection electrode 12 switches back and forth between two values. The solid line A represents the potential distribution in which there is no electric field in the first ionization chamber 13, because no potential difference is generated between the first counter electrode 11 and the first injection electrode 12. In this stage, the ions to be analyzed can be generated by means of the ionization source 3 and provided to the first ionization chamber 13. Therefore, the first ion gate 10 is closed in this state.

[0086] If a sufficient number of ions to be analyzed have accumulated in the first ionization chamber 13, the potential at the first injection electrode 12 is switched so that the potential distribution represented by the dashed line B is established. Then, due to the falling potential distribution, the ion packet located in the first ionization chamber 13 moves from the first ionization chamber 13 in the direction toward the first drift chamber 14. In this case, a first compression of the ion packet is achieved. After a certain period of time, when it can be assumed that the ion packet has passed the first injection electrode 12 but has not yet passed the first additional electrode 19, the potential at the first injection electrode 12 is switched again to the value that first appeared, so that the potential distribution represented by the solid line A appears again. In this state, as described above, the field strength in the first ionization chamber is substantially equal to zero. Then there is a relatively steep potential gradient in the space between the first injection electrode 12 and the first additional electrode 19, and therefore a relatively strong electric field, which leads to a second compression of the ion packet located in the gap. The ion packet, which has now been compressed for the second time, is then transferred to the first drift chamber 14.

[0087] exist Figure 4 It is further evident that it may be advantageous to define a second potential value which is applied to the first injection electrode 12 and which results in a potential distribution according to the dashed line B, so that in this operating phase the potential gradient between the first injection electrode 12 and the first additional electrode 19 is at least substantially equal to the potential gradient D in the first drift chamber 14. In this way it is ensured that ion packets are uniformly transferred from the gap between the first injection electrode 12 and the first additional electrode 19 into the first drift chamber 14.

[0088] Figure 5 An example of extended field switching is shown. Here, the potential of the first injection electrode 12 is also switched back and forth between two different values. First, it should be assumed that the potential value resulting in the potential distribution represented by the solid line A is applied to the first injection electrode 12. In this state, the first ion gate 10 is in a closed state, that is, the first ionization chamber 13 is substantially free of an electric field. In addition, the potential at the first injection electrode 12 is selected so that the potential is also constant in the gap between the first injection electrode 12 and the first additional electrode 19, and therefore the space is also substantially free of an electric field. In this way, the electric field caused by the potential gradient D in the first drift chamber 14 can be prevented from penetrating into the first ionization chamber 13.

[0089] The potential at the first injection electrode 12 is then switched to a different value so that a potential distribution is established as indicated by the dashed line B. In this case, the potential gradient between the first counter electrode 11 and the first injection electrode 12 corresponds, for example, to Figure 4 The potential distribution represented by the dashed line B in FIG. 1 ; similarly, the potential distribution between the first injection electrode 12 and the first additional electrode 19 may correspond to the reference Figure 4 The potential distribution is represented by the dashed line B. Therefore, in this state, the first ion gate is switched to transmission, so that the ion packet moves from the first ionization chamber 13 to the first drift chamber 14.

[0090] Figure 6 shows an exemplary potential distribution in the case of extended double field switching, so the above reference Figure 4 and Figure 5 In this case, the potential at the first injection electrode 12 is switched between three different values. It should be assumed that the sequence starts with a potential distribution according to the solid line A. In this state, the first ion gate 10 is closed, or in other words, the state corresponds to the above reference Figure 5 According to the state illustrated by the solid line A, the first ionization chamber 13 and the gap between the first injection electrode 12 and the first additional electrode 19 are substantially free of electric field. Therefore, the first additional electrode 19 can perform its function to shield the field punch-through from the first drift chamber 14.

[0091] Then, the potential at the first injection electrode 12 is switched so that a potential distribution indicated by the dashed line B is generated. In this state, the first ion gate 10 is opened. The ion packets that have accumulated in the first ionization chamber 13 move in the direction toward the first drift chamber 14 and are compressed for the first time in the process. This corresponds to the above reference Figure 4 and Figure 5 The same sequence is produced in the case of the potential distribution according to the dashed line B in the illustrated example.

[0092] The potential of the first injection electrode 12 is then switched again, so that the potential distribution represented by the dotted line C is generated. In this state, the first ion gate 10 is closed again. Therefore, the first ionization chamber 13 is essentially free of an electric field. However, in contrast to the potential distribution represented by the solid line A, this field-free state of the first ionization chamber 13 is obtained at a higher potential value. Therefore, in the gap between the first injection electrode 12 and the first additional electrode 19, there is a relatively strong electric field, i.e., a significant potential gradient, so that the ions located in the gap are compressed a second time before being transferred to the first drift chamber 14. In this case, the potential distribution according to the dotted line C may correspond, for example, to the potential distribution according to Figure 4 The solid line A is the potential distribution.

[0093] The potential at the first injection electrode 12 is then switched again to the value mentioned first, so that the potential according to Figure 6 The solid line A is the potential distribution.

[0094] Figure 7 A further embodiment of an ion mobility spectrometer with two drift chambers is shown, which are arranged one behind the other, i.e. as in Figure 1 As in the embodiment of Figure 1 In contrast to the embodiment, Figure 7 The ion migration spectrometer in the embodiment comprises a first additional electrode 19 in the IMS tube 1 and a second additional electrode 29 in the IMS tube 2. Thus, an ion migration spectrometer with two drift chambers can be provided, for example an ion migration spectrometer with bipolarity, which has corresponding functions for performing dual field switching, extended field switching and extended dual field switching. In this case, the potentials at the respective injection electrodes of the first ion gate 10 and the second ion gate 20 will be as described above for a system with only one IMS tube 1. Figure 3 It goes without saying that if it is intended to analyze ions with different polarities in the respective IMS tubes 1 , 2 , the potentials at the first injection electrode 12 and the second injection electrode 22 are switched in an opposite manner.

[0095] Figure 8 Another embodiment of an ion mobility spectrometer is shown, which is similar to Figure 7 Embodiment of. Figure 7On the contrary, the first counter electrode 11 and the second counter electrode 21 are omitted. Therefore, a common ionization chamber made of the first ionization chamber 13 and the second ionization chamber 23 is also formed. Therefore, the construction of the ion mobility spectrometer is simplified. In addition, ion losses can be further minimized. Nevertheless, all functions of the ion mobility spectrometer can still be achieved, including the above-mentioned extensions to dual field switching, extended field switching and extended dual field switching.

[0096] Fig. 9 It is shown that when double field switching is implemented, Figure 8 Example potential distribution of an ion mobility spectrometer. Figures 4 to 6 , again showing the potential difference U relative to the longitudinal extent s of the ion mobility spectrometer. In addition, the positions of the first ion detector 16 and the second ion detector 26, the first injection electrode 12 and the second injection electrode 22 and the first additional electrode 19 and the second additional electrode 29 are shown. Here, in different cases, the potential at the first injection electrode 12 and the second injection electrode 22 switches back and forth between two different values. The potential distribution with the solid line A represents the state in which the ion gates 10, 20 are closed. In the common ionization chamber, there is therefore a space without an electric field, and ions can be provided by the ionization source 3.

[0097] The potentials at the first injection electrode 12 and the second injection electrode 22 are then switched in opposite ways, so that a potential distribution represented by a dotted line B is generated. In this way, the positive ions and the negative ions are separated from each other and transmitted as corresponding separated ion packets in the direction toward the corresponding first drift chamber 14 or second drift chamber 24. In this case, the first compression of the corresponding ion packets is achieved.

[0098] Once the corresponding ion packet has passed the injection electrode 12 or 22 respectively assigned to it, the potential distribution can be switched again to the distribution according to the solid line A. In this state, a relatively steep potential gradient exists in the corresponding gaps of the first injection electrode 12 / first additional electrode 19 and the second injection electrode 22 / second additional electrode 29. A second compression of the corresponding ion packet is thus achieved. In this case, the sequence corresponds to the one already referred to Figure 4 Sequence described for one IMS tube 1. Sequence for a second IMS tube 2 results in the same sequence but with opposite polarity.

[0099] In the case of such an ion gate comprising an injection electrode and a counter electrode, in many applications the injection electrode is arranged closer to the drift chamber assigned to the ion gate than the counter electrode. In some applications, such as in the case of an ion mobility spectrometer with bipolarity, the arrangement may also be reversed, i.e. in such cases the counter electrode is arranged closer to the drift chamber assigned to the ion gate than the injection electrode.

[0100] Even according to Figure 8In the embodiment of the ion migration spectrometer, the first counter electrode and the second counter electrode are not present as separate components, and the functions of the corresponding counter electrodes are still present in the case of the function of switching the potential at the injection electrode described. With respect to the IMS tube 1 to which the first ion gate 10 is assigned, the second injection electrode 22 performs the function of the first counter electrode. In a corresponding manner, with respect to the second IMS tube 2 to which the second ion gate 20 is assigned, the first injection electrode 12 performs the function of the second counter electrode. As is apparent, the first injection electrode 12 and the second injection electrode 22 in the present embodiment have the functions of the first multifunctional electrode and the second multifunctional electrode described above.

[0101] It is also possible to switch the potential at the corresponding counter electrode and the corresponding injection electrode of the ion gate respectively and use the arrangement consisting of the three electrodes mentioned above, namely the counter electrode, the injection electrode and the additional electrode, to perform a method of double field switching, extended field switching and / or extended double field switching.

[0102] Fig.10 An ion mobility spectrometer having two drift chambers 14, 24 arranged in axial alignment is shown, the spectrometer being compared to the reference Figure 8 The described embodiment is simplified to a greater extent. Fig.10 The embodiment of again comprises two multifunctional electrodes formed by a first injection electrode 12 and a second injection electrode 22. Figure 8 Compared with the embodiment, Fig.10 The embodiment lacks the first additional electrode 19 and the second additional electrode 29. Even with this further simplified embodiment of the dual ion mobility spectrometer, the desired function in ion analysis can be achieved.

[0103] Fig.11 An embodiment of the potential distribution in the drift chambers 14, 24 and in the common ionization chambers 13, 23 is shown. Fig.11 , in the ion generation cycle, there is Figure 8 The embodiment of the invention has substantially the same potential distribution, but there is no potential gradient between the corresponding injection electrode and the additional electrode, because Fig.10 In the embodiment of FIG. 1 , no additional electrodes are present. This is due to Fig.11 The solid line in . According to the field switching principle, there is a potential gradient A in the common ionization chamber 13, 23, due to which the ionization chambers 13, 23 are substantially free of an electric field. A drift field with a potential gradient D exists in the first drift chamber 14 and in the second drift chamber 24. If, after a sufficient number of ions have accumulated in the ionization chambers 13, 23, the field switching ion gates are switched so that the ions are transferred to the corresponding drift chambers 14, 24 (ion injection cycle), this is achieved by switching the potential at the injection electrodes 12, 22, as indicated by Fig.11. A relatively steep potential gradient B then exists in the ionization chambers 13, 23. The potential level is changed in the respective drift chambers 14, 24, respectively, wherein the potential gradient E, i.e. the respective slope of the potential over the distance s, remains the same and corresponds to the slope of the potential gradient D. This is achieved by switching the potential at the respective detectors 16, 26 to the same amplitude as the potential at the respective injection electrodes 12, 22.

[0104] and Fig.11 compared to, Fig.12 An alternative embodiment of switching the potential is shown. During the ion generation cycle, there is Fig.11 The same state, namely the substantially neutral potential gradient A in the common ionization chamber 13, 23 and the corresponding potential gradient D in the drift chamber 14, 24. During the switching of the field-switched ion gates for transferring ions into the respective drift chambers 14, 24, the same state as in accordance with Fig.11 The same potential switching at the injection electrodes 12, 22 as described above, i.e., the potential gradient B is generated in the common ionization chamber 13, 23. Fig.11 In contrast, the potential at the detectors 16, 26 is not switched. This results in the corresponding potential gradient E in the drift chambers 14, 24 being smaller in magnitude than the potential gradient D, so that Fig.11 Compared to the variant in FIG. 1 , the movement speed of the ions in the respective drift chamber 14 , 24 is initially lower, ie during the ion implantation period. Then a switch to a higher potential gradient, for example the potential gradient D, may be realized again.

[0105] The above reference Fig.10 The switching type of potential described in the embodiment of the ion mobility spectrometer can also be advantageously used according to Figure 8 In an embodiment of an ion mobility spectrometer. Figure 8 In the embodiment of the invention, in addition to the multifunctional electrode formed by the injection electrodes 12, 22, there are additional electrodes 19, 29. This is also considered to be based on Fig.13 The ion mobility spectrometer of the embodiment of the present invention is based on Figure 8 In the ion mobility spectrometer, according to Fig.14 In this case, the potential distribution and the switching between the potential gradients A and B correspond to Fig.11 Similarly, Fig.11 Similarly, in the respective drift chambers 14, 24, the potential gradient is displaced in parallel between the ion generation period (potential gradient D) and the ion injection period (potential gradient E), i.e., the period during which the ions are transferred to the respective drift chambers 14, 24. In this case, the potential gradients D, E extend in parallel, which is achieved by switching the potential at the respective detectors 16, 26.

[0106] In addition, in the ion generation period in the corresponding space between the first injection electrode 12 and the first additional electrode 19 or between the second injection electrode 22 and the second additional electrode 29, a potential gradient is set, which is largely neutral, that is, substantially corresponds to the potential gradient A, but in this case can have a slight slope opposite to the potential gradient D in the respectively assigned drift chamber 14, 24. In this way, the penetration of the electric field from the corresponding drift chamber 14, 24 into the common ionization chamber 13, 23 can be offset by the corresponding additional electrodes 19, 29.

[0107] The switching of the potential can also be based on Fig.15 To achieve this, the switching type of potential basically corresponds to Fig.12 In the embodiment of Fig.12 Like in Fig.15 In FIG. 1 , the potentials at the detectors 16 , 26 are not switched, which results in a potential gradient E that is smaller in magnitude than the potential gradient D. In FIG.

[0108] Fig.16 An embodiment of an ion mobility spectrometer having an axially arranged drift chamber 14, 24 is shown, wherein, in addition to the multifunctional electrodes, namely the first injection electrode 12 and the second injection electrode 22 and the first additional electrode 19 and the second additional electrode 29, there are also corresponding further first additional electrodes 31 and further second additional electrodes 32, and the additional electrodes 31, 32 are arranged upstream of the corresponding additional electrodes 19, 29 in the direction of the corresponding drift chamber 14, 24.

[0109] Fig.17 Show according to Fig.16 The potential distribution in the ion generation period is again represented by a solid line, and the potential distribution in the ion injection period is represented by a dotted line. In this way, extended field switching can be advantageously achieved without changing the potential or potential distribution D in the corresponding drift chamber 14, 24. In this case, the transition of the potential gradient between the ion gate and the corresponding drift chamber can be adjusted by the additional first additional electrode 31 and the additional second additional electrode 32.

[0110] Fig.18 An ion mobility spectrometer with drift chambers 14, 24 arranged in parallel is shown, which spectrometer corresponds essentially to Figure 2 The embodiments in . Figures 19 to 22shows a favorable potential distribution in the ion generation period and the ion injection period. In this case, the upper half of each figure shows the potential distribution in the upper half of the ion mobility spectrometer, and the lower half of the figure shows the potential distribution in the lower half of the ion mobility spectrometer. For further distinction, here, the potential distribution in the upper half of the ion mobility spectrometer is represented by a solid line, and the potential distribution in the lower half is represented by a dotted line. This distribution also applies to Figure 24 to Figure 27 and Figure 29 to Figure 32 .

[0111] Fig.19 shows the potential distribution during the ion generation period, and Fig. 20 The associated potential distribution during the ion injection period is shown. It is assumed here that the two field-switched ion gates use a common injection electrode 12, 22, or that these injection electrodes 12, 22 are at the same potential. A common counter electrode 11, 21 is also possible. In this case, Fig.19 and Fig. 20 An advantageous switching cycle is shown during normal field switching operation of the ion gates 10, 20. In this case, potential switching is performed only at the respective counter electrodes 11, 21.

[0112] In contrast, Fig.21 and Fig. 22 The potential distribution is shown, where potential switching is performed at both the injection electrodes 12, 22 and the counter electrodes 11, 21, which Fig. 22 leads to an intersecting distribution of the potentials in the ionization chambers 13 and 23. In this case, Fig.21 The potential distribution during the ion generation cycle is shown again, and Fig. 22 The potential distribution during the ion implantation cycle is shown.

[0113] according to Fig.21 and Fig. 22 The advantage of the embodiment of is that the same field strength exists between the corresponding pair of counter-electrodes and injection electrodes, but the potential difference between the counter-electrodes 11, 21 is smaller. Thus, for example, malfunctions can be prevented. In addition, the drive is simplified because some potentials can be used variably. As is obvious, if the same potential gradient is ultimately to be obtained in the drift chambers 14, 24, then essentially corresponding to Fig.11 , Fig.12 The basis of the method Fig.21 and Fig. 22 Embodiments of the invention require switching of the potential at the respective detector 16, 26. Alternatively, the potential at the respective detector may be kept constant, which results in a reduction of the potential gradient in the respective drift chamber 14, 24.

[0114] Fig.23 shows that it corresponds to a large extent Fig.18An ion mobility spectrometer according to an embodiment of the present invention. Fig.18 On the contrary, Fig.23 In the embodiment of the present invention, the respective first additional electrode 19 and the second additional electrode 29 are arranged upstream of the respective drift chamber 14, 24. Fig.23 In an embodiment, extended field switching can be advantageously performed in both ion gates.

[0115] Fig.24 and Fig.25 Show Fig.23 Possible potential distributions of embodiments of Fig.24 and Fig.25 The potential distribution corresponds largely to Fig.19 and Fig.29 In this case, in the space between the respective injection electrode and the additional electrode, a shielding field having an opposite gradient to the field in the respective drift chamber is generated in order to counteract the punch-through of the field from the drift chamber into the ionization chamber. In this case, Fig.24 shows the potential distribution during the ion generation period, and Fig.25 The potential distribution during the ion implantation period is shown.

[0116] Fig.26 and Fig. 27 Shown with Fig.21 and Fig. 22 Comparable potential distribution. Fig.21 and Fig. 22 On the contrary, Fig.26 and Fig. 27 In this case, a corresponding field between the injection electrode and the additional electrode is generated again to counteract the field punch-through. Fig.26 shows the potential distribution during the ion generation period, and Fig. 27 The potential distribution during the ion implantation period is shown.

[0117] Fig.28 shows that it corresponds to a large extent Fig.23 An embodiment of an ion mobility spectrometer of an embodiment of the invention. Fig.23 On the contrary, Fig.28 In the embodiment of the present embodiment, the already mentioned further first additional electrode 31 and the further second additional electrode 32 are also present. In this case, the further first additional electrode 31 is arranged upstream of the first additional electrode 19 in the direction of the drift chamber 14 and the further second additional electrode 32 is arranged upstream of the second additional electrode 29 in the direction of the second drift chamber 24.

[0118] exist Fig.28 In an embodiment of the present invention, this configuration of electrodes makes it possible to achieve both extended field switching and double field switching, ie compression of ion packets in a second compression step.

[0119] Fig.29 and Fig.30 Show according to Fig.28 The favorable potential distribution of the ion mobility spectrometer is similar to Fig.19 and Fig. 20 This is reflected by the switching logic in . Fig.29 shows the potential distribution during the ion generation period, and Fig.30 The potential distribution during the ion implantation period is shown.

[0120] Fig.31 and Fig.32 Shows something like Fig.21 and Fig. 22 It is obvious that, in particular during the ion generation period, a relatively steep potential gradient is generated in the space between the respective additional electrode and the further additional electrode. Fig.31 shows the potential distribution during the ion generation period, and Fig.32 The potential distribution during the ion implantation period is shown.

[0121] Therefore, based on the steep potential gradient, Fig.29 and Fig.31 Also shown is a possible potential distribution for the second compression step during double field switching.

[0122] Reference numerals list

[0123] 1,2 ion mobility spectrometer (first IMS tube, second IMS tube) 3 ionization source

[0124] 10The First Ion Gate

[0125] 11. First counter electrode

[0126] 12. First injection electrode

[0127] 13. The first ionization chamber

[0128] 14First Drift Room

[0129] 15First field generating device

[0130] 16 First ion detector

[0131] 17 First drift gas inlet connector

[0132] 18 First drift gas outlet connector

[0133] 19 first additional electrode

[0134] 20 Second Ion Gate

[0135] 21 Second counter electrode

[0136] 22 Second injection electrode

[0137] 23 Second ionization chamber

[0138] 24 Second Drift Room

[0139] 25 Second field generating device

[0140] 26 Second ion detector

[0141] 27 Second drift gas inlet connector

[0142] 28 Second drift gas outlet connector

[0143] 29 second additional electrode

[0144] 31 Another first additional electrode

[0145] 32 Another second additional electrode

[0146] A Solid Line

[0147] B Dashed Line

[0148] C Point Line

[0149] D Potential gradient

[0150] U potential

[0151] s Longitudinal extent.

Claims

1. An ion mobility spectrometer (1, 2), comprising at least: A first drift chamber (14); a first ionization chamber (13); a switchable first ion gate (10), the first ion gate being used for controlled transfer of ions from the first ionization chamber (13) to the first drift chamber (14); a second drift chamber (24) separated from the first drift chamber (14); a second ionization chamber (23); and a switchable second ion gate (20), the second ion gate being used for controlled transfer of ions from the second ionization chamber (23) to the second drift chamber (24), wherein the first ionization chamber (13) and the second ionization chamber (23) can be designed as a common ionization chamber, Wherein, by means of an ionization source (3), ions to be analyzed can be generated from a sample, and the ions to be analyzed can be provided in the first ionization chamber (13) and the second ionization chamber (23) or in the common ionization chamber, characterized in that: a) the first ion gate (10) is designed as a field switching ion gate having a first counter electrode (11) and a first injection electrode (12), wherein the first ionization chamber (13) or the common ionization chamber extends from the first counter electrode (11) to the first injection electrode (12), wherein the ion mobility spectrometer (1, 2) is arranged to: during an ion generation period, provide the ions to be analyzed in the first ionization chamber (13) or the common ionization chamber in a state where the ionization chamber is substantially free of an electric field, so that during this ionization phase, the provided ions have not yet moved in any direction due to the electric field; and in an analysis step, switch at least one electrode of the field switching ion gate, thereby causing the ions to move in the direction of the first drift chamber (14), at least one first additional electrode (19) being arranged between the first ion gate (10) and the first drift chamber (14), the additional electrode ions to be transferred into the first drift chamber (14) through the first ion gate (10) being affected by the first additional electrode (19), and b) the second ion gate (20) is designed as a field switching ion gate having a second counter electrode (21) and a second injection electrode (22), wherein the second ionization chamber (23) or the common ionization chamber extends from the second counter electrode (21) to the second injection electrode (22), wherein the ion migration spectrometer (1, 2) is arranged to: during an ion generation period, provide the ions to be analyzed in the second ionization chamber (23) or the common ionization chamber in a state where the ionization chamber is substantially free of an electric field, so that during this ionization phase, the provided ions have not yet moved in any direction due to the electric field; and in an analysis step, switch at least one electrode of the field switching ion gate, thereby causing the ions to move in the direction of the second drift chamber (24), at least one second additional electrode (29) being arranged between the second ion gate (20) and the second drift chamber (24), the additional electrode ions to be transferred to the second drift chamber (24) through the second ion gate (20) being affected by the second additional electrode (29).

2. The ion mobility spectrometer (1, 2) according to claim 1, characterized in that The first ion gate (10) has at least a first counter electrode (11) and a first injection electrode (12), wherein a first ionization chamber (13) is formed between the first counter electrode (11) and the first injection electrode (12), and ions to be analyzed by ion mobility spectrometry can be fed from an ionization source (3) into the first ionization chamber.

3. The ion mobility spectrometer (1, 2) according to claim 1 or 2, characterized in that: The second ion gate (20) has at least a second counter electrode (21) and a second injection electrode (22), wherein a second ionization chamber (23) is formed between the second counter electrode (21) and the second injection electrode (22), and ions to be analyzed by ion mobility spectrometry can be fed from an ionization source (3) into the second ionization chamber.

4. The ion mobility spectrometer (1, 2) according to claim 3, characterized in that: The first counter electrode (11) and the second counter electrode (21) are short-circuited to each other or are designed as a common counter electrode, or the first injection electrode (12) and the second injection electrode (22) are short-circuited to each other or are designed as a common injection electrode.

5. The ion mobility spectrometer (1, 2) according to claim 1, characterized in that: The first additional electrode (19) and / or the second additional electrode (29) are designed to be potential-switchable.

6. The ion mobility spectrometer (1, 2) according to claim 1, characterized in that: The first additional electrode (19) and / or the second additional electrode (29) are designed to be potential non-switchable.

7. The ion mobility spectrometer (1, 2) according to claim 1, characterized in that: The first ion gate (10) and the second ion gate (20) are formed by a configuration comprising at least a first multifunctional electrode and a second multifunctional electrode, wherein the first multifunctional electrode is arranged upstream of the first drift chamber (14), and the second multifunctional electrode is arranged upstream of the second drift chamber (24), wherein the first multifunctional electrode forms the injection electrode (12) of the first ion gate (10), and the second multifunctional electrode forms the counter electrode (11) of the first ion gate (10), the second multifunctional electrode forms the injection electrode (22) of the second ion gate (20), and the first multifunctional electrode forms the counter electrode (21) of the second ion gate (20).

8. The ion mobility spectrometer (1, 2) according to any one of claims 1 to 7, characterized in that: The first drift chamber (14) and the second drift chamber (24) are arranged substantially in parallel adjacent to each other.

9. An ion mobility spectrometer (1, 2) according to any one of the preceding claims, characterized in that The ion mobility spectrometer (1, 2) does not include an additional field generating device (15, 25) for generating an electric field in the first ionization chamber (13) and / or the second ionization chamber (23), so that the electric field can be generated in the first ionization chamber (13) only by the electrodes of the first ion gate (10), and / or the electric field can be generated in the second ionization chamber (23) only by the electrodes of the second ion gate (20).

10. The ion mobility spectrometer (1, 2) according to any one of the preceding claims, characterized in that The ion mobility spectrometer (1, 2) comprises an X-ray ionization source, a UV ionization source, a corona ionization source, a plasma ionization source, a dielectric barrier discharge source and / or an electron emitter as an ionization source (3).

11. A method for analyzing a sample by ion mobility spectrometry using an ion mobility spectrometer (1, 2) according to any one of the preceding claims, wherein ions to be analyzed are generated from the sample by means of an ionization source (3) and provided in a first ionization chamber (13) and a second ionization chamber (23) or in the common ionization chamber, and the positive ions and negative ions thus generated are guided through separate drift chambers (14, 24) to separate corresponding ion detectors (16, 26) under the control of corresponding first ion gates (10) and second ion gates (20), characterized in that: a) providing the ions to be analyzed in the first ionization chamber (13) or the common ionization chamber in a state where the ionization chamber is substantially free of an electric field during the ion generation period, so that during this ionization phase the provided ions have not yet been moved in any direction due to the electric field, and in the analysis step, switching at least one electrode of the field switching ion gate, thereby causing the ions to move in the direction of the first drift chamber (14), at least one first additional electrode (19) being arranged between the first ion gate (10) and the first drift chamber (14), the additional electrode ions to be transferred into the first drift chamber (14) through the first ion gate (10) being influenced by the first additional electrode (19), and b) providing the ions to be analyzed in the second ionization chamber (23) or the common ionization chamber in a state where the ionization chamber is substantially free of an electric field during the ion generation period, so that during this ionization phase the provided ions have not yet moved in any direction due to the electric field, and in the analysis step, switching at least one electrode of the field switching ion gate, thereby causing the ions to move in the direction of the second drift chamber (24), at least one second additional electrode (29) being arranged between the second ion gate (20) and the second drift chamber (24), the additional electrode ions to be transferred into the second drift chamber (24) through the second ion gate (20) being affected by the second additional electrode (29).

12. The method according to claim 11, characterized in that The first counter electrode (11) and the second counter electrode (21) have the same potential.

13. An ion mobility spectrometer (1, 2), comprising at least: A first drift chamber (14); a first ionization chamber (13); a switchable first ion gate (10), the first ion gate being used for controlled transfer of ions from the first ionization chamber (13) to the first drift chamber (14); a second drift chamber (24) separated from the first drift chamber (14); a second ionization chamber (23); and a switchable second ion gate (20), the second ion gate being used for controlled transfer of ions from the second ionization chamber (23) to the second drift chamber (24), wherein the first ionization chamber (13) and the second ionization chamber (23) can be designed as a common ionization chamber, Wherein, by means of an ionization source (3), ions to be analyzed can be generated from a sample, and the ions to be analyzed can be provided in the first ionization chamber (13) and the second ionization chamber (23) or in the common ionization chamber, characterized in that: a) the first ion gate (10) is designed as a field switching ion gate having a first counter electrode (11) and a first injection electrode (12), wherein the first ionization chamber (13) or the common ionization chamber extends from the first counter electrode (11) to the first injection electrode (12), wherein the ion mobility spectrometer (1, 2) is configured to: during an ion generation period, provide the ions to be analyzed in the first ionization chamber (13) or the common ionization chamber in a state where the ionization chamber is substantially free of an electric field, so that during this ionization phase, the provided ions have not yet moved in any direction due to the electric field; and in an analysis step, switch at least one electrode of the field switching ion gate, thereby causing the ions to move in the direction of the first drift chamber (14), at least one first additional electrode (19) being arranged between the first ion gate (10) and the first drift chamber (14), the additional electrode ions to be transferred into the first drift chamber (14) through the first ion gate (10) being affected by the first additional electrode (19), and b) the second ion gate (20) is designed as a field switching ion gate having a second counter electrode (21) and a second injection electrode (22), wherein the second ionization chamber (23) or the common ionization chamber extends from the second counter electrode (21) to the second injection electrode (22), wherein the ion migration spectrometer (1, 2) is configured to: during an ion generation period, provide the ions to be analyzed in the second ionization chamber (23) or the common ionization chamber in a state where the ionization chamber is substantially free of an electric field, so that during this ionization phase, the provided ions have not yet moved in any direction due to the electric field; and in an analysis step, switch at least one electrode of the field switching ion gate, thereby causing the ions to move in the direction of the second drift chamber (24), c) wherein the first counter electrode (11) and the second counter electrode (21) are short-circuited together or are designed as a common counter electrode, or the first injection electrode (12) and the second injection electrode (22) are short-circuited together or are designed as a common injection electrode.

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