CN101093211B - Transient Drift Electric Field Method for Ion Mobility Spectrometer Drift Tube - Google Patents

Abstract

The present invention is a kind of transient electric field method for drift tube of ion mobility spectrometer, relates to detection technology, and it uses transient electric field as the drift electric field in the drift tube of ion mobility spectrometer (IMS), namely at time (T +mΔT) to (T+(m+1)ΔT), the ion clusters all drift to the area between the m+1th, m+2th, and m+3th drift electrodes. , m+2th and m+3th drift electrodes respectively apply voltages V _(m+1)(m+1) , V _(m+1)(m+2) and V _{(m+1)(m+ 3)} Satisfy V _(m+1)(m+1) -V _(m+1)(m+2) = V _(m+1)(m+2) -V _(m+1)(m+3) =EL, the region between the m+1th, m+2th and m+3th drift electrodes of the drift tube constitutes a transient electric field with an intensity of E. The transient drift electric field method of the invention can greatly reduce the required voltage, and is beneficial to the integration of the ion mobility spectrometer circuit, and the integration of the ion mobility spectrometer micro-drift tube and the circuit.

Description

Transient Drift Electric Field Method for Ion Mobility Spectrometer Drift Tube

technical field

The invention relates to the technical field of detection, belongs to ion mobility spectrometer (IMS: Ion Mobility Spectrometer) technology, and in particular relates to a transient electric field and a method for generating a transient electric field used in a drift tube of an ion mobility spectrometer.

Background technique

Ion mobility spectrometry is a new detection technology developed in the late 1960s. It is somewhat similar to time-of-flight mass spectrometry, but ion mobility spectrometry does not require high vacuum conditions like mass spectrometry , but work at atmospheric pressure. Ion mobility spectrometer has good selectivity and high detection sensitivity, and is an effective tool for detecting trace explosives, drugs, and biochemical warfare agents.

The ion mobility spectrometer separates different substances according to the difference in the mobility of ions in a weak electric field (about 200V/cm order) under atmospheric pressure. It is mainly composed of drift tube, peripheral circuit, gas system and sampling system. The drift tube is the place where ions form and drift, and is the most important special device in the ion mobility spectrometer (IMS). Its performance directly determines the index of the entire ion mobility spectrometer; the gas circuit system and the sampling system provide The working environment and conditions of the ion mobility spectrometer; the peripheral circuit completes the process control, signal acquisition and data processing functions of the ion mobility spectrometer.

The drift tube is mainly composed of four parts: 1 ionization chamber; 2 ion drift region; 3 ion control gate located between the ionization chamber and ion drift region; 4 Faraday disk as ion detector. When using an ion mobility spectrometer (IMS) to detect a sample, the analyte (which can be a gas or a particle) is first ionized in the ionization chamber to form charged ions, and then the ions enter the ion drift region through the ion control gate, under the action of an electric field After a certain time of drifting to the Faraday disk, the ion mobility can be calculated by measuring the time it takes for the ion to pass through the ion drift region. Ion mobility is affected by external factors such as drift gas, temperature, and pressure. Under certain conditions, the mobility of small ions mainly depends on its molecular weight, while the mobility of large ions is mainly determined by the collision cross section. Since the mobilities of ions of various substances are different under certain conditions, the relevant information of the sample can be indirectly obtained by measuring the drift time.

Compared with general chemical analysis instruments, ion mobility spectrometer (IMS) has the advantages of small size, light weight, and low power consumption. Its detection sensitivity for explosives, drugs and other substances is as high as 10 ^-8 -10 ^-14 g or ppb (10 ^-9 )-ppt(10 ^-12 ) level, especially suitable for real-time detection of luggage packages.

In the schematic diagram of the ion mobility spectrometer (IMS) shown in Figure 1, there are multiple drift electrodes in the ion drift region, and the ion mobility spectrometer (IMS) instrument of the traditional structure is to add a constant voltage to each drift electrode, Establish a drift electric field with a required strength of about 200V/cm in the entire space of the drift region, which requires the use of a high-voltage power supply of the order of 1000V. The circuit is not easy to integrate, and it is even more difficult to use relatively mature IC technology to achieve.

Contents of the invention

The purpose of the present invention is to provide a kind of transient electric field idea and the method that produce for ion mobility spectrometer (IMS) drift tube. Using the present invention can produce drift electric field in ion mobility spectrometer (IMS) drift tube The required voltage is reduced to tens of volts or even several volts, and it is relatively easy to use ordinary IC circuits to generate drift electric fields, which is beneficial to the integration of ion mobility spectrometer (IMS) circuits and the miniature drift of ion mobility spectrometers (IMS). The integration of tubes and circuits is of great significance.

In order to achieve the above object, the technical solution of the present invention is to provide a kind of transient electric field method for ion mobility spectrometer drift tube, it uses transient electric field as the drift electric field in the ion mobility spectrometer drift tube, i.e. Between the time (T+mΔT) and (T+(m+1)ΔT), the ion clusters all drift to the area between the m+1th, m+2, and m+3th drift electrodes, where the drift tube Voltages V (m+1)(m+1), V _(m+1)(m+2) and V ( _{m+1) are applied to the m+1, m+2} and _m +3 drift electrodes respectively _)(m+3) , V _(m+1)(m+1) , V _(m+1)(m+2) and V _(m+1)(m+3) satisfy V _{(m+1)( m+1)} -V _(m+1)(m+2) ＝V _(m+1)(m+2) -V _(m+1)(m+3) ＝EL, in the m+1th drift tube , The region between the m+2th and m+3th drift electrodes constitutes a transient electric field with a strength E.

Described transient drift electric field method, its steps are:

S1. Under the action of a drift electric field with an intensity of E, the time required for the ions to be detected to pass through the area between adjacent drift electrodes with a distance of L is ΔT=L/EK, where K is the mobility of ions, then at time T Between (T+ΔT), apply voltages V ₁₁ , V ₁₂ and V 13 to the first, second and third drift electrodes _of the drift tube respectively, and V ₁₁ , V ₁₂ and V ₁₃ satisfy V ₁₁ -V ₁₂ =V ₁₂ -V ₁₃ =EL, a transient electric field with intensity E is formed in the area between the first, second and third drift electrodes of the drift tube, during this time the ion cluster to be detected is located at the first drift tube , In the region between the second and the third drift electrodes and subjected to the transient electric field, the T is the moment when all the ion clusters enter the ion drift region;

S2. Between the time (T+ΔT) and (T+2ΔT), the ion cluster drifts to the area between the second, third, and fourth drift electrodes, where the second, third, and fourth electrodes of the drift tube Voltages V ₂₂ , V ₂₃ and V ₂₄ are respectively applied to the drift electrodes, and V ₂₂ , V ₂₃ and V ₂₄ satisfy V ₂₂ -V ₂₃ =V ₂₃ -V ₂₄ =EL, in the second, third and fourth of the drift tube The region between the drift electrodes constitutes a transient electric field with a strength E;

S3. Between the time (T+2ΔT) and (T+3ΔT), the ion cluster drifts to the area between the third, fourth, and fifth drift electrodes, where the third, fourth, and fifth electrodes of the drift tube Voltages V ₃₃ , V ₃₄ and V 35 are respectively applied to the drift electrodes _. V ₃₃ , V ₃₄ and V ₃₅ satisfy V ₃₃ -V ₃₄ =V ₃₄ -V ₃₅ =EL. The region between the drift electrodes constitutes a transient electric field with a strength E;

S4. Repeat steps S1, S2, and S3 above to control the voltages of three adjacent drift electrodes to form a transient electric field with an intensity of E in the area between them. Every time ΔT passes, the controlled drift electrodes move backward Move one in order, so that the space region where the ion cluster to be detected always has a transient electric field with an intensity of E;

S5. Make all the ion clusters to be detected drift to the Faraday disk.

In the described transient drift electric field method, the voltage applied to different drift electrodes has a waveform of a square wave, a triangular wave, a sawtooth wave, a sine wave, or a superposition of the above-mentioned various waveforms, or an irregular waveform .

The invention uses a low voltage to generate a transient electric field that moves with the ion drift of the measured substance to replace the steady state drift electric field generated by a high voltage in a traditional ion mobility spectrometer (IMS). The present invention adds transient voltages to different drift electrodes of the drift tube to generate the required drift electric field. The frequency of the voltage applied to the drift electrodes in the drift region is determined by the mobility of the measured object and the size of the drift region. The size is determined by the required drift electric field strength and the distance between the drift electrodes. The waveform of the voltage applied to the drift electrodes in the drift region and the phase relationship of the voltages on different drift electrodes can be adjusted according to theoretical analysis and experimental data.

The idea and method of the transient drift electric field proposed by the present invention greatly reduce the voltage required by the ion mobility spectrometer (IMS) to establish the drift electric field, which is beneficial to the integration of the ion mobility spectrometer (IMS) circuit.

Description of drawings

Fig. 1 is the structure diagram of ion mobility spectrometer (IMS);

Fig. 2 is the schematic diagram of voltage applied on the drift electrode of traditional ion mobility spectrometer (IMS);

Fig. 3 is a kind of schematic diagram of voltage applied to each drift electrode of the ion mobility spectrometer (IMS) drift tube illustrating the basic principle of the transient drift electric field of the method of the present invention;

Fig. 4 is a schematic diagram of voltages applied to each drift electrode of an ion mobility spectrometer (IMS) drift tube that realizes a transient drift electric field according to the method of the present invention;

Fig. 5 is another kind of ion mobility spectrometer (IMS) drift tube voltage schematic diagram that realizes the drift electric field of another kind of the present invention;

Fig. 6 is a schematic diagram of the voltages applied to each drift electrode of the drift tube of an ion mobility spectrometer (IMS) improved by the method of the present invention to realize the transient drift electric field.

Detailed ways

The principle of the transient electric field method used in the ion mobility spectrometer drift tube of the present invention is as follows:

When the charged ions are accelerated and moved forward under the action of the drift electric field, they will collide with the neutral drift gas molecules and decelerate, and then the ions will continue to be accelerated by the electric field, and then decelerate after collision, and so on. This microscopic movement of ions is manifested in the macroscopic view that ions obtain an average drift velocity v _d , in the case of a weak electric field, it is proportional to the electric field strength E: v _d =KE, the proportionality constant K in the formula is the ion's Mobility is a physical quantity related to factors such as the mass, size, collision cross section, and dipole moment of ions and drift gas molecules. It is also affected by external factors such as temperature and air pressure. The ion mobility K is a characteristic of a compound (or a functional group, an ion), which is related to a moving gas. Under a low electric field strength, the mobility of a specific ion can be calculated according to the Mason-Schamp equation [E A Mason, Ion mobility: Its role in plasma chromartograhpy, TW Carr, Ed., New York: Plenum Press, 1984, 43] and other theoretical and experimental data to determine.

The movement of ions in the drifting electric field is determined by the force on the ions, and the electric field force on the ions at a moment is only related to the electric field in the area where it is at this moment. That is to say, theoretically, if the electric field strength in the region where the ions are located is always E at each moment during the drift process, the movement of the ions is the same as that in a steady and uniform electric field with the strength E. According to this principle, it is not necessary to maintain the electric field of the entire ion drift region during the whole process of drifting, but only need to maintain the drift electric field of the region where the ion is located. The macroscopic performance of ions moving in the ion drift region is well known. According to the electric field strength of the ion drift region and the mobility K of a specific ion, the position of the ion in the ion drift region at a certain moment can be known, and only the required drift can be established in this region. The electric field is enough to ensure the drift of the ions, which can significantly reduce the voltage required to establish the drift electric field.

For the convenience of discussion, referring to FIG. 1 , it is assumed that there are N drift electrodes 6 uniformly arranged in the drift tube of the ion mobility spectrometer (IMS) shown in FIG. 1 , and the distance between them is L. The mobility of a particular ion we need to detect is K. Then under the action of the drift electric field with the intensity E, the time ΔT=L/KE required for the ions to pass through the region between adjacent electrodes 6 .

Consider the motion of a specific ion with mobility K in a drift electric field.

In a traditional ion mobility spectrometer (IMS), by applying a constant voltage (V ₀ -nEL) to the nth electrode 6 (where n=1, 2, 3...N, V ₀ is a constant) To obtain a drift electric field of strength E requires a power supply with a voltage of at least ((N-1)EL). And in the method of the present invention, between moment T to (T+ΔT), ion is in the region between the first, the second electrode 6, during this period of time on the first, the second electrode 6 respectively Apply voltages V ₁₁ , V ₁₂ , V ₁₁ and V ₁₂ satisfy V ₁₁ -V ₁₂ =EL; between time (T+ΔT) and (T+2ΔT), ions have moved to the second and third electrodes 6 During this period, voltages V ₂₂ and V 23 are respectively applied to the second and third electrodes 6, and V ₂₂ and _{V 23 satisfy} V ₂₂ -V ₂₃ =EL;...at time (T+(n -1) Between ΔT) and (T+nΔT), ions move to the area between the nth and (n+1)th drift electrodes 6, at time (T+(n-1)ΔT) to (T+ nΔT) time, apply voltages V _nn and V _{n(n+1) to the nth and (n+1} )th drift electrodes 6 respectively, and V _nn and V _n(n+1) satisfy V _nn -V _{n( n+1)} = EL (n=1, 2, 3...N in the formula), so that the required power supply voltage only needs to be higher than (EL), which is only 1/N-1 of the voltage used in the traditional method .

The above discussion is only the basic principle of the present invention. In fact, because the ion clusters are distributed in a certain space, and the switching of the voltage on the drift electrode 6 takes a certain time, only the ion mobility of the drift electric field is established between two adjacent drift electrodes 6. The performance of the spectrometer (IMS) is very poor, and only a very small number of ions in the ion cluster can complete the drift process. Considering the distribution of ion clusters, voltage switching, and uniformity of the drift electric field, a drift electric field should be established between at least three adjacent drift electrodes. The present invention is used for the transient drift electric field method of the ion mobility spectrometer drift tube, and the steps of establishing a drift electric field between three adjacent drift electrodes are:

S1. Under the action of a drift electric field with an intensity of E, the time required for the ions to be detected to pass through the area between adjacent drift electrodes with a distance of L is ΔT=L/KE, where K is the mobility of ions, then at time Between T and (T+ΔT), voltages V ₁₁ , V ₁₂ and V 13 are respectively applied to the first, second and third drift electrodes 6 _of the drift tube, and V ₁₁ , V ₁₂ and V ₁₃ satisfy V ₁₁ - V ₁₂ =V ₁₂ -V ₁₃ =EL, the region between the first, second and third drift electrodes 6 of the drift tube constitutes a transient electric field with an intensity of E, and during this time the ion clusters to be detected are located in the drift The region between the first, second and third drift electrodes 6 of the tube is subjected to the transient electric field. Any voltage can be applied to other drift electrodes 6 of the drift tube except the first, second and third drift electrodes 6 or they can be in a suspended state. The T is the moment when all the ion clusters enter the ion drift region.

S2. Between the time (T+ΔT) and (T+2ΔT), the ion cluster drifts to the area between the second, third and fourth drift electrodes 6, where the second, third and fourth drift tubes Voltages V ₂₂ , V ₂₃ and V 24 are applied to each drift electrode 6 respectively, and V ₂₂ , V ₂₃ and _{V 24 satisfy} V ₂₂ -V ₂₃ =V ₂₃ -V ₂₄ =EL, and the second, third and third drift tubes The region between the four drift electrodes 6 constitutes a transient electric field with a strength E. Any voltage can be applied to other drift electrodes 6 of the drift tube except the second, third and fourth drift electrodes 6 or they can be in a suspended state.

S3. Between the time (T+2ΔT) and (T+3ΔT), the ion cluster drifts to the area between the third, fourth and fifth drift electrodes 6, where the third, fourth and fifth drift tubes Voltages V ₃₃ , V ₃₄ and V 35 are respectively applied to each drift electrode 6, and V ₃₃ , _{V 34} and V ₃₅ satisfy V ₃₃ -V ₃₄ =V ₃₄ -V ₃₅ =EL. The region between the five drift electrodes 6 constitutes a transient electric field with a strength E. Any voltage can be applied to other drift electrodes 6 of the drift tube except the third, fourth, and fifth drift electrodes 6 or they can be in a suspended state.

S4. Repeat the above steps to control the voltages of the three adjacent drift electrodes to form a transient electric field with an intensity E in the area between them. Every time ΔT passes, the controlled drift electrodes will move backward one by one, A transient electric field with an intensity E always exists in the spatial region where the ion cluster to be detected is located.

That is, between the time (T+mΔT) and (T+(m+1)ΔT), the ion cluster drifts to the area between the m+1th, m+2th, and m+3th drift electrodes, where Voltages V (m+1)(m+1), V _(m+1)(m+2) and V _{(m+1) are respectively applied to the m+1, m+2 and m} +3 drift electrodes 6 _)(m+3) , V _(m+1)(m+1) , V _(m+1)(m+2) and V _(m+1)(m+3) satisfy V _{(m+1)( m+1)} -V _(m+1)(m+2) ＝V _(m+1)(m+2) -V _(m+1)(m+3) ＝EL, in the m+1th drift tube The regions between the , m+2, and m+3 drift electrodes 6 form a transient electric field with an intensity E. Any voltage can be applied to other drift electrodes 6 of the drift tube except the m+1th, m+2th, and m+3rd drift electrodes 6 or they can be in a suspended state.

S5 , causing all the ion clusters to be detected to drift to the Faraday disk 7 .

Assuming that the distribution length of the ion clusters to be detected in the drift direction is l, if l and L satisfy l<L, then at time T, all the ion clusters are located in the area between the first and second drift electrodes. Under the action of the state drift electric field, all the ions in the ion cluster can drift to the Faraday disk 7 (the collision loss and diffusion of ions are not considered and the transient drift electric field is assumed to be a uniform electric field).

If l and L cannot satisfy l<L, it is impossible to make the ion clusters to be detected drift to the area between the m+1th and m+2th drift electrodes at the time (T+mΔT), that is, the area before this time Between the last two drift electrodes among the three adjacent drift electrodes forming the transient electric field during the ΔT time period, it is impossible to make all the ions of the ion cluster drift to the Faraday disk 7 under the action of the transient electric field.

It is assumed that l<hL, where h is an integer greater than 1. In order to make all the ions in the ion cluster drift to the Faraday disk 7 to improve the sensitivity of the ion mobility spectrometer (IMS), a transient electric field should be established between at least h+1 adjacent drift electrodes. The method is similar to the method of establishing a transient electric field between three adjacent drift electrodes: control the voltage of adjacent h+1 drift electrodes to form a transient electric field with an intensity of E in the area between them, and every time At the time of ΔT, the controlled drift electrode will move backwards one by one, so that the space region where the ion cluster to be detected is located always has a transient electric field with an intensity of E.

The concrete implementation method of the present invention is illustrated below in conjunction with accompanying drawing:

Figure 1 shows the schematic diagram of the principle and structure of an ion mobility spectrometer (IMS). In the figure, sample inlet 1, ionization source 2, ionization chamber 3, ion control gate 4, ion drift region 5, drift electrode 6, Faraday disk 7, drift gas inlet 8, drift gas outlet 9, peripheral circuit 10, etc. , the specific structure is a known technology, and will not be described in detail here.

The sample enters the ionization chamber 3 from the injection port 1. After the ionization chamber 3 is ionized, it enters the ion drift region 5 through the ion control gate 4, and passes through the ion drift region 5 under the action of an electric field, and the ions are detected by the Faraday disk 7. The relevant information of the sample can be obtained by analyzing the drift spectrum. There are a plurality of drift electrodes 6 in the ion drift region 5, and the ion mobility spectrometer (IMS) instrument of traditional structure is to add a constant voltage at each drift electrode 6, and establishes the required drift electric field in the whole space of the drift region 5 (such as 200V/cm), it needs to use a high voltage of thousands of volts, which is difficult to realize with integrated circuits.

FIG. 2 is a schematic diagram of voltage applied to each drift electrode 6 in a conventional ion mobility spectrometer (IMS). In the figure, the voltage applied to each drift electrode 6 is a constant voltage, and the voltage difference applied to adjacent drift electrodes 6 with a spacing of L is EL, so that a steady and constant drift electric field with an intensity E is formed in the entire drift region 5 . To form the drift electric field, a power source with a voltage of at least (N−1)EL is used, where N is the number of drift electrodes 6 .

Fig. 3 is a schematic diagram of voltage applied to each drift electrode 6 of the drift tube of an ion mobility spectrometer (IMS) illustrating the basic principle of the transient drift electric field of the method of the present invention. The voltage applied to each drift electrode 6 in the figure has only two states, which are V and V+EL respectively. The waveform of the voltage applied to control each drift electrode 6 is shown in Figure 3. Then, during the time period from T to (T+ΔT), Since the applied voltages on the adjacent drift electrodes 11 and drift electrodes 12 with a spacing of L are V+EL and V respectively, a drift electric field with an intensity of E is formed in the space between the drift electrodes 11 and the drift electrodes 12; the same principle, in During the time period from (T+ΔT) to (T+2ΔT), the space between the drift electrode 12 and the drift electrode 13 forms a drift electric field with a strength of E... During (T+(n-1)ΔT) to (T+nΔT) During the period of time, the space between the drift electrodes (n+10) and the drift electrodes (n+11) forms a drift electric field with a strength E, where n=1, 2...N-1, N is the number of drift electrodes. In this way, a transient drift electric field that moves with time can be formed in the entire ion drift region. Adjusting the time parameter ΔT can make the moving speed of the electric field the same as the drift speed of the ion to be detected. The motion in the steady drift electric field is the same, but the power supply voltage required by the method of the present invention only needs to be higher than EL, which is only 1/N-1 of the voltage used in the traditional method.

Fig. 4, Fig. 5 are respectively two kinds of other ion mobility spectrometer (IMS) drift tubes of the present invention that realize the transient drift electric field. and triangular wave, it can be guaranteed that in the time period from T to (T+ΔT), there is a drift electric field with an intensity of E in the space between the adjacent drift electrodes 11 and 12 with a spacing of L; (T+2ΔT) time period, there is a drift electric field with strength E in the space between the adjacent drift electrodes 12 and 13 with a distance of L..., which can form an instant moving with time in the entire ion drift region state drift electric field.

The proposed transient drift electric field of the inventive method can be used for various forms of ion mobility spectrometer (IMS) drift tubes. Transient drift electric field of drift tube of instrument (IMS).

The transient drift electric field proposed by the present invention can have various forms, and Fig. 4 and Fig. 5 are just two examples thereof. According to the type of substance to be detected, professionals can easily select many other forms of transient drift electric field from the idea of the present invention. The content of the present invention includes but not limited to the transient drift electric field shown in Figures 3, 4, and 5 Implementation. The waveform of the voltage applied to each drift electrode 6 of the drift tube may be a square wave, a triangle wave, a sawtooth wave, a sine wave, etc., or a superposition of the above-mentioned various waveforms, or various irregular waveforms.

It should be pointed out that Fig. 3, Fig. 4, and Fig. 5 are only schematic diagrams illustrating the method of the present invention, without considering factors such as the certain spatial distribution of ion clusters, the time required for electrode voltage switching, and the uniformity of the drift electric field. After considering the above factors, only a small proportion of ions in the ion cluster can pass through the transient electric field drift shown in Figure 3, Figure 4, and Figure 5. In order to improve the performance of the transient electric drift field, it is necessary to establish the electric drift field between at least three adjacent drift electrodes at the same time.

FIG. 6 is a schematic diagram of voltages applied to each drift electrode 6 to simultaneously establish a drift electric field between three adjacent drift electrodes 6 in the method of the present invention. The voltage applied to each drift electrode 6 in the figure has only three states, which are V, V+EL, and V+2EL respectively. The waveform of the voltage applied to control each drift electrode 6 is shown in Figure 6. ) time period, since the applied voltages on the adjacent drift electrodes 11, 12, and 13 with a spacing of L are V+2EL, V+EL, and V respectively, the space between the drift electrodes 11, 12, and 13 forms an intensity of E The drift electric field; the same principle, in the time period from (T+ΔT) to (T+2ΔT), the space between the drift electrodes 12, 13, 14 forms a drift electric field with an intensity of E...at (T+(n-1) During the period from ΔT) to (T+nΔT), the space between the drift electrodes (n+10), (n+11), (n+12) forms a drift electric field with a strength of E, where n=1, 2...N -2, where N is the number of drift electrodes. In this way, a transient electric field that moves with time can be formed in the entire ion drift region 5, and adjusting the time parameter ΔT can make the moving speed of the electric field the same as the drift speed of the ion cluster to be detected, that is, in (T+(n-1) ΔT) to (T+nΔT), the ion group moves from the space between the drift electrodes (n+10) and (n+11) to the space between the drift electrodes (n+11) and (n+12) space. This can ensure that the electric field strength in the area where the ion cluster is located is always E, and the motion of the ion cluster is the same as the motion in the steady drift electric field whose strength is E, and the required power supply voltage required by the method of the present invention only needs to be higher than 2EL That's it. In the same principle, the same transient electric field as shown in FIG. 6 can also be realized by adding voltage signals of other waveforms such as triangular wave and sine wave to the three adjacent drift electrodes 6 .

In the method of the present invention, the frequency of the voltage signal applied to the drift electrode 6 is determined by the mobility of the measured object and the size of the drift region. Generally, the drift speed of ions in a weak electric field of 200V/cm is about 5-10m/s. If the distance L between the drift electrodes 6 is on the order of millimeters or centimeters, the time ΔT required for ions to pass through the area between adjacent drift electrodes 6 On the order of 10 ^-4 seconds or 10 ^-3 seconds, the frequency of the voltage signal applied to the drift electrode 6 is on the order of 10 KHz or less. With the reduction of the size of the drift region and the increase of the number of drift electrodes 6, the frequency of the voltage signal will increase, but it is still within the achievable range of the integrated circuit.

Claims (3)

1. production method that is used for the transient state drift field of ion migration ratio spectrometer drift tube, it is characterized in that: use transient electric field as the drift field in the ion migration ratio spectrometer drift tube, promptly constantly between (T+m Δ T) to (T+ (m+1) Δ T), ionic group all floats to the zone between m+1, m+2, the m+3 drift electrode, distinguishes making alive V on drift tube m+1, m+2 and m+3 drift electrode _{(m+1) (m+1)}, V _{(m+1) (m+2)}And V _{(m+1) (m+3)}, V _{(m+1) (m+1)}, V _{(m+1) (m+2)}And V _{(m+1) (m+3)}Satisfy V _{(m+1) (m+1)}-V _{(m+1) (m+2)}=V _{(m+1) (m+2)}-V _{(m+1) (m+3)}=EL is the transient electric field of E at drift tube m+1, m+2 and m+3 zone formation intensity of drifting about between the electrode.

2. the production method of transient state drift field as claimed in claim 1 is characterized in that: step is:

S1, be under the drift field effect of E in intensity, the ion that need to detect is that regional required time is Δ T=L/KE between the adjacent drift electrode of L by spacing, wherein K is the mobility of ion, then arrive between (T+ Δ T) difference making alive V on first, second, third drift of drift tube electrode at moment T ₁₁, V ₁₂And V ₁₃, V ₁₁, V ₁₂And V ₁₃Satisfy V ₁₁-V ₁₂=V ₁₂-V ₁₃=EL, it is the transient electric field of E that zone between first, second, third drift of drift tube electrode constitutes intensity, in the zone of the ionic group that needs during this period of time to detect between first, second, third of drift tube drift electrode and be subjected to this transient electric field effect, described T is the moment that ionic group all enters the ion drift district;

S2, constantly between (T+ Δ T) to (T+2 Δ T), ionic group float to second, third, the zone between the 4th drift electrode, making alive V respectively on drift tube second, third and the 4th drift electrode ₂₂, V ₂₃And V ₂₄, V ₂₂, V ₂₃And V ₂₄Satisfy V ₂₂-V ₂₃=V ₂₃-V ₂₄=EL, drift tube second, third, to constitute intensity be the transient electric field of E in the 4th zone of drift between the electrode;

S3, constantly between (T+2 Δ T) to (T+3 Δ T), ionic group floats to the the 3rd, the 4th, the 5th zone between the drift electrode, making alive V respectively on drift tube the 3rd, the 4th and the 5th drift electrode ₃₃, V ₃₄And V ₃₅, V ₃₃, V ₃₄And V ₃₅Satisfy V ₃₃-V ₃₄=V ₃₄-V ₃₅=EL, it is the transient electric field of E that the zone between the the 3rd, the 4th, the 5th drift of drift tube electrode constitutes intensity;

S4, repeat above S1, S2, S3 step, the voltage of controlling adjacent three drift electrodes is the transient electric field of E with formation intensity of the zone between it, every time through Δ T, in check drift electrode just backward order pass 1, making the area of space that needs the ionic group place detected that intensity always be arranged is that the transient electric field of E exists;

S5, the ionic group that needs are detected all float to faraday's dish.

3. the production method of transient state drift field as claimed in claim 1 or 2, it is characterized in that: the described voltage that is added on the different drift electrodes, its waveform is square wave, triangular wave, sawtooth wave, sine wave, or the stack of above-mentioned various waveforms, or irregular waveform.

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