IMS analysis device

Abstract

To provide an IMS analyzer with which it is possible to obtain an IMS spectrum with stable detection sensitivity, and which has improved quantitativity.SOLUTION: An IMS analyzer according to the present invention comprises an analysis chamber, an electron discharge element, an ion detection unit, a first gas injection unit which is provided so as to inject a sample gas into the analysis chamber, a second gas injection unit which is provided so as to inject a drift gas into the analysis chamber, a third gas injection unit which is provided so as to inject a primary ion generation gas into the analysis chamber, and an exhaust port. The first, second and third gas injection units and the exhaust port are provided so that the sample gas joins with the drift gas and the primary ion generation gas in a reaction region and is ejected from the exhaust port. The ion detection unit is disposed upstream of the reaction region in the drift gas flow, and the electron discharge element is disposed upstream of the reaction region in the primary ion generation gas flow.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an IMS analyzer. [Background technology]

[0002] Conventional IMS analyzers use radiation, corona discharge, etc. to ionize sample gases. Because radiation and corona discharge have high energy, the sample gas may be chemically decomposed during ionization. In this case, the detector detects many ions generated by the decomposition of the sample gas, resulting in many peaks appearing in the IMS spectrum. This makes it difficult to identify the sample gas in IMS analysis. An IMS analyzer is known that ionizes a sample gas using low-energy electrons emitted from an electron-emitting element (see, for example, Patent Document 1). This analyzer can prevent the sample gas from chemically decomposing, making it easier to identify the sample gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-186190 Summary of the Invention [Problem to be solved by the invention]

[0004] In IMS spectra obtained using an IMS analyzer that uses an electron emitter, the detection sensitivity can be unstable and the air peak can split, resulting in low quantitative accuracy in IMS analysis. The present invention has been made in view of the above circumstances, and provides an IMS analyzer that can obtain an IMS spectrum with stable detection sensitivity and improved quantitative performance. [Means for solving the problem]

[0005] The present invention provides an IMS analysis apparatus comprising: an analysis chamber; an electron emitter disposed in the analysis chamber; an ion detection unit disposed in the analysis chamber; a first gas injection unit configured to inject a sample gas into the analysis chamber; a second gas injection unit configured to inject a drift gas into the analysis chamber; a third gas injection unit configured to inject a gas for generating primary ions into the analysis chamber; and an outlet configured to discharge gas from the analysis chamber, wherein the first gas injection unit, the second gas injection unit, the third gas injection unit and the outlet are configured so that the sample gas joins with the drift gas and the gas for generating primary ions in a reaction region and is discharged from the outlet, the ion detection unit is disposed upstream of the reaction region in the flow of the drift gas, and the electron emitter is disposed upstream of the reaction region in the flow of the gas for generating primary ions. [Effects of the Invention]

[0006] The electron emitter is located upstream of the reaction region in the flow of the primary ion generation gas. This prevents the sample gas from reaching the electron emitter, stabilizing the gas composition near the electrode (surface electrode) on the electron emission side of the electron emitter (leading to a state in which the primary ion generation gas flows). The gas flow in the analysis chamber can also be stabilized. Near the electrode on the electron-emitting side of the electron-emitting element, electrons emitted from the electron-emitting element collide with gas and generate primary ions (negative ions or positive ions). Since the gas composition near the electrode is stabilized by the primary ion generating gas, the amount of primary ions generated can also be stabilized. In addition, the ion species of the primary ions can also be stabilized. These primary ions act as mediators. The generated primary ions migrate to the reaction region due to the flow of primary ion generation gas and the electric field formed in the analysis chamber. There, they transfer charge to the target component contained in the sample gas injected from the first gas injection unit, generating negative or positive ions (ion-molecule reaction). Because the flow of primary ion generation gas stabilizes the amount and ion species of primary ions and the gas flow in the analysis chamber, the amount of target component ions generated in the reaction region is stabilized. Furthermore, the ion species of target component ions generated in the reaction region are also stabilized. Because these ions reach and are detected in the ion detection unit, the detection sensitivity in the IMS spectrum can be stabilized even when the analysis is repeated multiple times. Furthermore, the intensity of the peaks appearing in the IMS spectrum can be stabilized. This improves the quantitative performance of IMS analysis. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of an IMS analyzer according to one embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view of an IMS analyzer according to one embodiment of the present invention. [Figure 3] (a) and (b) are explanatory diagrams of the structure of the IMS analyzer used for the IMS analysis, and (c) is an IMS spectrum. [Figure 4] (a) and (b) are explanatory diagrams of the structure of the IMS analyzer used for the IMS analysis, and (c) is an IMS spectrum. [Figure 5] (a) and (b) are explanatory diagrams of the structure of the IMS analyzer used for the IMS analysis, and (c) is an IMS spectrum. DETAILED DESCRIPTION OF THE INVENTION

[0008] The IMS analysis apparatus of the present invention comprises an analysis chamber, an electron emitter disposed in the analysis chamber, an ion detection unit disposed in the analysis chamber, a first gas injection unit configured to inject a sample gas into the analysis chamber, a second gas injection unit configured to inject a drift gas into the analysis chamber, a third gas injection unit configured to inject a gas for generating primary ions into the analysis chamber, and an outlet configured to discharge gas from the analysis chamber, wherein the first gas injection unit, the second gas injection unit, the third gas injection unit, and the outlet are configured so that the sample gas merges with the drift gas and the gas for generating primary ions in a reaction region and is discharged from the outlet, the ion detection unit is disposed upstream of the reaction region in the flow of the drift gas, and the electron emitter is disposed upstream of the reaction region in the flow of the gas for generating primary ions.

[0009] The first gas injector, the second gas injector and the third gas injector are preferably provided so as to inject gas into the analysis chamber from different positions. The third gas injection unit is preferably provided to inject the primary ion generating gas into the analysis chamber when the first gas injection unit is injecting the sample gas into the analysis chamber. The primary ion generating gas is preferably air containing moisture, an oxygen-containing gas, or a chlorine-containing gas, which allows primary ions to be stably generated near the surface electrode of the electron-emitting device. The pressure in the analysis chamber is preferably 630 hPa or more and 1120 hPa or less, which makes the pressure in the analysis chamber almost the same as atmospheric pressure, allowing the IMS analysis device to be made smaller.

[0010] Preferably, the third gas injection unit has an injection port provided to inject the primary ion generation gas into the analysis chamber, and the electron emitter is disposed between the injection port and the reaction region, thereby allowing the primary ion generation gas to flow stably around the electron emitter and enabling stable generation of primary ions near the surface electrode of the electron emitter. Preferably, the third gas injector is configured to inject air having a higher relative humidity than the drift gas into the analysis chamber, thereby increasing the detection sensitivity of the IMS analyzer. The third gas injector is preferably configured to inject air having a relative humidity of 0.5% to 10% into the analysis chamber, thereby increasing the detection sensitivity of the IMS analyzer.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The configurations shown in the drawings and the following description are merely examples, and the scope of the present invention is not limited to those shown in the drawings and the following description.

[0012] 1 and 2 are schematic cross-sectional views of the IMS analysis device of this embodiment. The IMS analysis apparatus 40 of the present invention comprises an analysis chamber 30, an electron emitter 2 arranged in the analysis chamber 30, an ion detection unit 6 arranged in the analysis chamber 30, a first gas injection unit 16 arranged to inject a sample gas into the analysis chamber 30, a second gas injection unit 15 arranged to inject a drift gas into the analysis chamber 30, a third gas injection unit 12 arranged to inject a gas for generating primary ions into the analysis chamber 30, and an outlet 20 arranged to discharge gas from the analysis chamber 30, wherein the first gas injection unit 16, the second gas injection unit 15, the third gas injection unit 12 and the outlet 20 are arranged so that the sample gas merges with the drift gas and the gas for generating primary ions in the reaction region 10 and is discharged from the outlet 20, and the ion detection unit 6 is arranged upstream of the reaction region 10 in the flow of the drift gas, and the electron emitter 2 is arranged upstream of the reaction region 10 in the flow of the gas for generating primary ions. The IMS analyzer 40 is an apparatus that analyzes a sample by ion mobility spectrometry (IMS). The analyzer 40 may be an ion mobility spectrometer. The analyzer 40 may be an IMS analyzer that performs analysis by a drift tube IMS. Furthermore, the sample gas analyzed by the IMS analyzer 40 may be a gas sample or a vaporized liquid sample.

[0013] The IMS analyzer 40 has an analysis chamber 30 (inside the housing 28) that analyzes target components contained in a sample gas. The housing 28 can have a rectangular or convex cross section. The IMS analyzer 40 shown in Figures 1 and 2 has a convex cross section. The analysis chamber 30 is equipped with an ion detection unit 6, an electron emitter 2, an electrostatic gate electrode 8, an electric field generating electrode 9, and the like. A sample gas is injected into the analysis chamber 30 through a first gas injection unit 16, a drift gas is injected into the analysis chamber 30 through a second gas injection unit 15, and a gas for generating primary ions is injected into the analysis chamber 30 through a third gas injection unit 12. Gas in the analysis chamber 30 is exhausted through an exhaust port 20. The analysis chamber 30 may have a reaction region 10 and an ion migration region 11. The pressure in the analysis chamber 30 may be set to 630 hPa or more and 1120 hPa or less. This allows the pressure in the analysis chamber 30 to be approximately the same as atmospheric pressure, making it possible to miniaturize the IMS analyzer. The reaction region 10 is a region where the components to be detected are ionized, and the ion migration region 11 is a region where the ionized components to be detected migrate to the ion detection unit against the flow of the drift gas.

[0014] The electron emitter 2 is provided to emit electrons from the surface electrode 4, and is an element that uses the emitted electrons to ionize gas in the vicinity of the electron emitter 2 (surface electrode 4) to generate primary ions (negative ions or positive ions). The electron emitter 2 has a lower electrode 3, a surface electrode 4, and an intermediate layer 5 disposed between the lower electrode 3 and the surface electrode 4. The electron emitter 2 can be disposed so that the surface electrode 4 faces the reaction region 10. This allows the primary ions generated near the surface electrode 4 to be stably supplied to the reaction region 10. The surface electrode 4 is an electrode located on the surface of the electron emitter 2. The surface electrode 4 may preferably have a thickness of 10 nm or more and 100 nm or less. The surface electrode 4 may be made of, for example, gold or platinum. The surface electrode 4 may also be made of multiple metal layers. Even if the surface electrode 4 has a thickness of 40 nm or more, it may have multiple openings, gaps, or thinned portions with a thickness of 10 nm or less. Electrons that flow through the intermediate layer 5 can pass through or penetrate these openings, gaps, or thinned portions, and can be emitted from the surface electrode 4. Such openings, gaps, or thinned portions can also be formed by applying a voltage between the lower electrode 3 and the surface electrode 4.

[0015] The lower electrode 3 is an electrode that faces the surface electrode 4 via the intermediate layer 5. The lower electrode 3 may be a metal plate, or a metal layer or a conductive layer formed on an insulating substrate or a film. When the lower electrode 3 is made of a metal plate, this metal plate may also be the substrate of the electron-emitting element 2. The material of the lower electrode 3 is, for example, aluminum, stainless steel, nickel, or the like. The thickness of the lower electrode 3 is, for example, 200 μm or more and 1 mm or less.

[0016] The intermediate layer 5 is a layer in which electrons flow due to an electric field formed by applying a voltage between the surface electrode 4 and the lower electrode 3. The intermediate layer 5 may be semiconductive. The intermediate layer 5 may contain at least one of an insulating resin, insulating fine particles, and a metal oxide. The intermediate layer 5 preferably contains conductive fine particles. The thickness of the intermediate layer 5 may be, for example, 0.5 μm or more and 1.8 μm or less. The intermediate layer 5 is, for example, a silicone resin layer having silver fine particles dispersed therein.

[0017] The surface electrode 4 and the lower electrode 3 can each be electrically connected to a control unit. The control unit is provided to control the magnitude of the voltage (driving voltage of the electron-emitting element 2) applied between the surface electrode 4 and the lower electrode 3. When the potential of the lower electrode 3 is made substantially the same as the potential of the surface electrode 4 using the control unit (driving voltage is set to 0 V), no current flows through the intermediate layer 5 and electrons are not emitted from the electron-emitting element 2. When a voltage (driving voltage) is applied between the lower electrode 3 and the surface electrode 4 using a control unit so that the potential of the lower electrode 3 is lower than the potential of the surface electrode 4, a current flows through the intermediate layer 5, and electrons that flow through the intermediate layer 5 pass through the surface electrode 4 and are emitted from the electron-emitting element 2. The voltage applied between the lower electrode 3 and the surface electrode 4 to emit electrons from the electron-emitting element 2 can be, for example, 5 V or more and 40 V or less.

[0018] The control unit is a part that controls the IMS analyzer. The control unit may include, for example, a microcontroller having a CPU, memory, timer, input / output ports, etc. The control unit may also include an electric field control unit, a gate control unit, a driving voltage control unit, a recovery current measurement unit, a power supply unit, etc.

[0019] The third gas injection unit 12 is a part that injects a primary ion generation gas into the analysis chamber 30. The primary ion generation gas is a gas that is supplied around the electron emitter 2 and receives electrons emitted from the electron emitter 2 to generate primary ions. The primary ion generation gas is, for example, moisture-containing air, oxygen-containing gas, oxygen gas, chlorine-containing gas, or chlorine gas. Preferably, the primary ion generation gas is air with a constant humidity (for example, a relative humidity (temperature 10°C to 30°C, 1 atmosphere) of 0.5% to 10%, or a moisture content (molar fraction) of 30 ppmv to 5000 ppmv). In addition, the relative humidity of the primary ion generation gas is preferably higher than that of the drift gas. This can increase the detection sensitivity of the IMS analyzer 40. By including oxygen molecules and water molecules in the primary ion generating gas, primary ions can be generated stably near the front electrode 4.

[0020] The third gas injection unit 12 may have an injection port for injecting a gas for generating primary ions into the analysis chamber 30. The third gas injection unit 12 may also include a gas cylinder, an air compressor, a blower, a humidity adjustment unit, etc. The humidity adjustment unit is provided so that the humidity of the gas for generating primary ions injected into the analysis chamber 30 is constant (for example, a humidity adjustment unit).

[0021] The primary ion generation gas injected into the analysis chamber 30 by the third gas injection unit 12 flows around the electron emitter 2 and into the reaction region 10. In other words, the electron emitter 2 is disposed upstream of the reaction region 10 in the flow of the primary ion generation gas. 1 and 2, a third gas injection unit 12 and an electron emitter 2 can be provided so that the primary ion generation gas injected into the analysis chamber 30 flows around the electron emitter 2 and reaches the reaction region 10. As shown in Fig. 1, the electron emitter 2 may be disposed between the injection port of the third gas injection unit 12 and the reaction region 10. Alternatively, as shown in Fig. 2, the third gas injection unit 12 may be provided so as to inject the primary ion generation gas from the side into the space behind the lower electrode 3 of the electron emitter 2.

[0022] By providing such a third gas injection part 12, it is possible to prevent the sample gas from reaching the electron emitter 2, and the air around the electron emitter 2 can be stably used as a gas for generating primary ions. As a result, it is possible to stabilize the amount and species of primary ions generated by the electrons emitted from the electron emitter 2, and it is possible to stabilize the detection sensitivity in the IMS spectrum. In addition, the amount of primary ions can be adjusted by adjusting the voltage applied between the surface electrode 4 and the lower electrode 3 (adjusting the amount of electrons emitted by the electron emitter 2), etc.

[0023] When electrons are emitted from the electron emitter 2 (surface electrode 4) into the primary ion generation gas, the electrons immediately collide with the components of the primary ion generation gas to form primary ions (negative ions or positive ions). When the electrons emitted from the electron emitter 2 attach to the gas components near the surface electrode 4 (electron attachment phenomenon), negative ions of the gas components are generated. When the energy of the electrons emitted from the electron emitter 2 is higher than the ionization energy of the gas components near the surface electrode 4, positive ions of the gas components are generated. When the primary ion generation gas is air containing moisture, the primary ions (negative ions) are, for example, O2 - , O.H. - And so on.

[0024] The primary ions generated near the electron emitter 2 (surface electrode 4) move to the reaction region 10 due to the electric field formed in the analysis chamber 30 by the electron emitter 2, electrostatic gate electrode 8, electric field forming electrode 9, etc., and the flow of primary ion generating gas injected into the analysis chamber 30 by the third gas injection unit 12. The primary ions act as charge transport mediators that transfer charge to the detection target components in the reaction region 10.

[0025] The electric field in the analysis chamber 30 is formed by controlling the potentials of the electron emitting device 2, the electrostatic gate electrode 8, the electric field forming electrode 9, the ion detection unit 6, and the like by the control unit. The control unit controls the potentials of the electron emitter 2, electrostatic gate electrode 8, electric field forming electrode 9, ion detection unit 6, etc. so that a potential gradient is formed that causes primary ions generated near the electron emitter 2 (surface electrode 4) to move toward the reaction region 10. The control unit also controls the potentials of the electron emitter 2, electrostatic gate electrode 8, electric field forming electrode 9, ion detection unit 6, etc. so that a potential gradient is formed that causes ions that have passed through the electrostatic gate electrode 8 to move toward the ion detection unit 6. The slope of the potential gradient formed is opposite when detecting the target gas contained in the sample gas as negative ions (negative ion mode) and when detecting the target gas contained in the sample gas as positive ions (positive ion mode).

[0026] The first gas injection unit 16 is a unit that injects a sample gas containing a component to be analyzed into the analysis chamber 30. The first gas injection unit 16 may also be provided to inject the sample gas together with a carrier gas into the analysis chamber 30. The first gas injection unit 16 may also be provided to inject the sample gas (or the sample gas plus a carrier gas) into the reaction region 10 of the analysis chamber 30. The first gas injection unit 16 may have an injection port for injecting sample gas into the analysis chamber 30. The first gas injection unit 16 may also include a gas cylinder, an air compressor, a blower, a sample vaporization chamber, etc. The first gas injection unit 16 may also include a mixing chamber for mixing a carrier gas with a sample (sample gas or liquid sample), or a dilution unit for diluting the sample gas with the carrier gas. The carrier gas is a gas that is injected into the analysis chamber 30 together with the sample gas, and is, for example, air, helium gas, argon gas, nitrogen gas, etc. The distance from the injection port of the first gas injection unit 16 to the electron emitter 2 can be set to 5 cm or more. This makes it possible to prevent the sample gas from reaching the electron emitter 2. In addition, the electron emitter 2 can be arranged so that the injection direction of the sample gas from the first gas injection unit 16 is parallel to the surface electrode 4 of the electron emitter 2. This makes it possible to prevent the sample gas from reaching the electron emitter 2.

[0027] The sample gas injected into the reaction region 10 from the first gas injection unit 16 merges in the reaction region 10 with the primary ion generation gas flowing from the electron emitter side and the drift gas flowing from the ion detection unit 6 side, and is then exhausted from the exhaust port 20. This airflow can prevent the sample gas from flowing toward the electron emitter 2. The exhaust port 20 may be provided so as to forcibly exhaust the gas in the analysis chamber 30 using an exhaust fan or the like, or may be provided so as to naturally exhaust the gas in the analysis chamber 30. The ratio of the injection flow rate of the sample gas (or sample gas + carrier gas) injected into the analysis chamber 30 using the first gas injection unit 16 to the injection flow rate of the gas for generating primary ions injected into the analysis chamber 30 using the third gas injection unit 12 can be, for example, 0.5 or more and 2 or less.

[0028] The inlet of the first gas inlet 16 can be provided adjacent to the reaction region 10. The outlet 20 can also be provided adjacent to the reaction region 10. When the housing 28 has a rectangular or convex cross section, the inlet of the first gas inlet 16 can be provided in a first side wall of the housing 28 that forms the analysis chamber 30 or protruding from this first side wall, and the outlet 20 can be provided in a second side wall opposite the first side wall or protruding from this second side wall. When the housing 28 has a rectangular or convex cross section, the inlet of the third gas inlet 12 can be provided in a third side wall of the housing 28 or protruding from the third side wall, and the inlet of the second gas inlet 15 can be provided in a fourth side wall opposite the third side wall or protruding from the fourth side wall. Also, when the housing 28 has a convex cross section, the inlet of the first gas inlet 16 and the inlet and outlet 20 of the third gas inlet 12 can be located in the protruding part (narrowed part) of the housing 28. When the housing 28 has a rectangular or convex cross section, the electron emitter 2 can be positioned at a position 5 cm or more away from the position where the inlet of the first gas injection section 16 is provided in the direction of the inlet of the third gas injection section 12, with the surface electrode 4 facing the reaction region 10.

[0029] In the reaction region 10, the sample gas, primary ion generation gas, and drift gas are mixed to form a mixed gas. Furthermore, primary ions are moved to the reaction region 10 by the electric field and the flow of the primary ion generation gas. These primary ions transfer charge to the detection target component contained in the sample gas in the reaction region 10, generating negative or positive ions of the detection target component contained in the sample gas (ion-molecule reaction). Because the amount and type of primary ions are stabilized by flowing the primary ion generation gas, the detection target component can be ionized stably (in terms of amount and type) in the reaction region 10.

[0030] The second gas injection unit 15 is a unit provided to inject drift gas into the analysis chamber 30. The drift gas is a gas that flows in the ion migration region 11 in the opposite direction to the ion migration direction and acts as a resistance when the ions move through the ion migration region 11. The drift gas may be purified atmospheric air (clean air), air supplied from a compressed air cylinder, or purified air exhausted from the analysis chamber 30 through the exhaust port 20. The drift gas may be helium gas, argon gas, or nitrogen gas. The second gas injection unit 15 and the exhaust port 20 are provided so that the drift gas flows from the ion detection unit side toward the electrostatic gate electrode side in the ion migration region 11. For example, the second gas injection unit 15 may be provided to supply the drift gas to the ion migration region 11 from the ion detection unit side. The flow rate of the drift gas injected into the analysis chamber 30 using the second gas injection unit 15 can be made greater than the total flow rate of the injection flow rate of the first gas injection unit 16 and the injection flow rate of the third gas injection unit 12. This stabilizes the airflow in the ion migration region 11, thereby improving the ion separation performance of the IMS analysis device 40.

[0031] The electrostatic gate electrode 8 is an electrode disposed between the reaction region 10 and the ion migration region 11, and controls the injection of ions generated in the reaction region 10 into the ion migration region 11 by utilizing the electrostatic interaction between the ions and the electrostatic gate electrode 8. The electrostatic gate electrode 8 is, for example, a grid-shaped electrode (shutter grid). The electrostatic gate electrode 8 can be arranged in a line together with a plurality of electric field forming electrodes 9. The electrostatic gate electrode 8 can be electrically connected to a control unit. The electrostatic gate electrode 8 is also provided so as to be able to change the potential gradient formed in the analysis chamber 30.

[0032] The control unit changes the potential of the electrostatic gate electrode 8 to instantaneously change from low potential side closed (a state in which the potential of the electrostatic gate electrode 8 is low and ions cannot pass through the electrostatic gate electrode 8 and move to the ion migration region 11) to high potential side closed (a state in which the potential of the electrostatic gate electrode 8 is high and ions cannot pass through the electrostatic gate electrode 8 and move to the ion migration region 11), or to instantaneously change from high potential side closed to low potential side closed. This allows the electrostatic gate electrode 8 to be in an open state for only a very short time, and ions can be injected into the ion migration region 11 only during this short time. Therefore, ions can be injected into the ion migration region 11 in a single pulse.

[0033] Negative or positive ions injected into the ion migration region 11 migrate through the ion migration region 11 toward the ion detection unit 6 due to the potential gradient formed in the analysis chamber 30, and reach the ion detection unit 6. At this time, the negative or positive ions move against the flow of the drift gas. This drift gas flow acts as a resistance for the negative or positive ions moving from the electrostatic gate electrode 8 toward the ion detection unit 6. The magnitude of this resistance (ion mobility) varies depending on the ion species. Generally, mobility is inversely proportional to the ion's collision cross-section (ion size). Therefore, the larger the ion's collision cross-section, the longer it takes for the ion to reach the ion detection unit 6. (The larger the ion, the more frequently it collides with air molecules in the drift gas, resulting in a slower migration speed and a longer arrival time at the ion detection unit 6.) Therefore, the time (arrival time, peak position) from when an ion is injected into the ion migration region 11 by the electrostatic gate electrode 8 to when it reaches the ion detection unit 6 varies depending on the ion species (negative or positive ion). Therefore, it is possible to identify negative or positive ions (detection target components contained in the sample) based on this arrival time (peak position). In addition, ions of multiple detection target components contained in the sample gas can be separated in the ion migration region 11.

[0034] The ion detection unit 6 is a metal member that collects the electric charge of negative or positive ions. The ion detection unit 6 can be electrically connected to a recovery current measurement unit of the control unit. This recovery current measurement unit is also configured to measure, in time series, the recovery current generated when negative or positive ions transfer their electric charge to the ion detection unit 6. This makes it possible to measure the current waveform (IMS spectrum) of the recovery current.

[0035] Multiple ions injected into the ion migration region 11 in a single pulse using the electrostatic gate electrode 8 are separated into various ions as they move through the ion migration region 11, and the various ions arrive at the ion detection unit 6 with a time delay. As a result, the current waveform (IMS spectrum) of the collected current exhibits peaks corresponding to the arrival times of the various ions. The mobility can be calculated from the peak positions (arrival times) and the ion components can be identified. This allows the detection and identification of the target components. Furthermore, because the peak heights or peak areas of the current waveform of the collected current correspond to the amount of charge transferred by the various ions to the ion detection unit 6, quantitative analysis of the target components can be performed based on the peak heights or peak areas.

[0036] In the present invention, the third gas injection unit 12 is used to supply primary ion generation gas around the electron emitter 2, thereby stabilizing the ion species and ion production amount of the primary ions generated near the surface electrode 4, and also stabilizing the ion species and ion production amount of the ions of the target component generated in the reaction region 10. This stabilizes the ion species and ion quantity of the ions of the target component that reach the ion detection unit 6, and also stabilizes the current waveform (IMS spectrum) of the collected current. As a result, the use of the IMS analysis device of the present invention can improve the quantitativeness of IMS analysis. Furthermore, it can simplify the detection and identification of the target component.

[0037] IMS analysis An IMS analysis was performed to analyze sample gas (air with a relative humidity of 80% or air with a relative humidity of 0.4%) using an IMS analysis device (comparative example) in which an electron-emitting device 2 was arranged as shown in Figures 3(a) and 3(b). This IMS analysis device does not have a third gas injection unit 12. Air with a relative humidity of 0.4% was used as the drift gas, and the electron-emitting device 2 was arranged so that the sample gas injected from the first gas injection unit 16 into the analysis chamber 30 hit the electron-emitting device 2. The driving voltage of the electron-emitting device 2 was 13V. Figure 3(c) shows the IMS spectrum when the sample gas was air with a relative humidity of 80% and the IMS spectrum when the sample gas was air with a relative humidity of 0.4%. As shown in the graph in Figure 3(c), a large peak appeared in the IMS spectrum when the sample gas was air with a relative humidity of 80%. On the other hand, no large peak appeared in the IMS spectrum when the sample gas was air with a relative humidity of 0.4%. This is thought to be because the relative humidity of the sample gas has a significant effect on the generation of ions by electrons emitted from the electron emitter 2.

[0038] An IMS analysis was performed to analyze a sample gas (air with a relative humidity of 80% or air with a relative humidity of 0.4%) using an IMS analysis device (comparative example) in which an electron-emitting device 2 was arranged as shown in Figures 4(a) and 4(b). In this IMS analysis device, the electron-emitting device 2 was arranged away from the injection port of the first gas injection part 16, and a third gas injection part 12 was not provided. Air with a relative humidity of 0.4% was used as the drift gas. The driving voltage of the electron-emitting device 2 was 16V. FIG. 4(c) shows the IMS spectrum when the sample gas was air with a relative humidity of 80% and the IMS spectrum when the sample gas was air with a relative humidity of 0.4%. As shown in the graph in Figure 4(c), when the relative humidity of the sample gas was 80%, a peak at approximately 10.8 ms (drift time) and a peak at approximately 11.4 ms appeared in the IMS spectrum. When the relative humidity of the sample gas was 0.4%, the peak at approximately 10.8 ms became smaller and the peak at approximately 11.4 ms became larger.

[0039] An IMS analysis was performed to analyze a sample gas (air with a relative humidity of 80% or 0.4%) using an IMS analyzer (embodiment) with an electron-emitting device 2 arranged as shown in Figures 5(a) and 5(b). This IMS analyzer was equipped with a third gas injection unit 12. Air with a relative humidity of 0.4% was used as the drift gas, and air with a relative humidity of 0.4% was used as the primary ion generation gas. The electron-emitting device 2 was positioned away from the injection port of the first gas injection unit 16, and the third gas injection unit 12 was installed so as to inject the primary ion generation gas into the analysis chamber 30 from behind the electron-emitting device 2 (the side of the lower electrode 3). The driving voltage of the electron-emitting device 2 was 18V. Figure 5(c) shows the IMS spectrum when the sample gas was air with a relative humidity of 80% and the IMS spectrum when the sample gas was air with a relative humidity of 0.4%. As shown in the graph in Figure 5(c), even when the relative humidity of the sample gas was changed, the intensity of the peaks that appeared in the IMS spectrum remained almost unchanged. This is thought to be because, even when the relative humidity of the sample gas was changed, primary ions were stably generated near the surface electrode of the electron emitter 2 by flowing the primary ion generation gas around the electron emitter 2. [Explanation of symbols]

[0040] 2: Electron emitter 3: Lower electrode 4: Surface electrode 5: Intermediate layer 6: Ion detection section 8: Electrostatic gate electrode 9: Electric field forming electrode 10: Reaction region 11: Ion migration region 12: Third gas injection section 15: Second gas injection section 16: First gas injection section 20: Outlet 28: Housing 30: Analysis chamber 40: IMS analysis device

Claims

1. an analysis chamber; an electron emitter disposed in the analysis chamber; an ion detector disposed in the analysis chamber; a first gas injection unit provided to inject a sample gas into a reaction region of the analysis chamber; a second gas injection unit provided to inject a drift gas into the analysis chamber; a third gas injection unit provided to inject a gas for generating primary ions into the analysis chamber; an exhaust port provided to exhaust gas from the analysis chamber; and an electrostatic gate electrode that controls the movement of ions, including ions generated near the surface of the electron emitter, toward the ion detector; the electrostatic gate electrode is disposed between the electron emitter and the ion detector; the first gas injection part, the second gas injection part, the third gas injection part and the exhaust port are provided so that the sample gas merges with the drift gas flowing from the ion detection part side and the primary ion generation gas flowing from the electron emitter side in the reaction region and is exhausted from the exhaust port; the ion detection unit is disposed upstream of the reaction region in the flow of the drift gas, the electron emitting device is disposed upstream of the reaction region in the flow of the primary ion generating gas; an outlet for discharging the primary ion generation gas injected from the third gas injection part is not provided on the ion detection part side of the electrostatic gate electrode, at a position overlapping with the electron emitter, or on the opposite side of the electron emitter from the electrostatic gate electrode side, but is provided only on the electrostatic gate electrode side of the electron emitter, on the electron emitter side of the electrostatic gate electrode side of the electrostatic gate electrode, and at a position overlapping with the first gas injection part.

2. An IMS analysis apparatus as described in claim 1, wherein the first gas injection section, the second gas injection section, and the third gas injection section are each configured to inject gas into the analysis chamber from different positions.

3. An IMS analysis apparatus as described in claim 1 or 2, wherein the third gas injection unit is configured to inject the primary ion generating gas into the analysis chamber when the first gas injection unit is injecting sample gas into the analysis chamber.

4. 4. The IMS analysis apparatus according to claim 1, wherein the gas for generating primary ions is air containing moisture, an oxygen-containing gas, or a chlorine-containing gas.

5. 5. The IMS analysis apparatus according to claim 1, wherein the pressure in the analysis chamber is 630 hPa or more and 1120 hPa or less.

6. The third gas injection unit has an injection port provided to inject the primary ion generating gas into the analysis chamber, 6. The IMS analysis apparatus according to claim 1, wherein the electron-emitting device is disposed between the injection port and the reaction region.

7. An IMS analysis device described in any one of claims 1 to 6, wherein the third gas injection section is configured to inject air having a higher relative humidity than the drift gas into the analysis chamber.

8. An IMS analysis device described in any one of claims 1 to 7, wherein the third gas injection section is configured to inject air having a relative humidity of 0.5% or more and 10% or less into the analysis chamber.

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