A method for regulating the progress of ion-molecule reactions in a photoionization source

Abstract

The present application relates to a method for regulating the ion-molecule reaction process in a photoionization source. The method comprises a sample gas, a sample inlet pipeline, a valve, a vacuum ultraviolet light source, an ionization source cavity, an inlet electrode, a light introduction electrode, an outlet electrode and a mass analyzer. The light emitted by the vacuum ultraviolet light source is perpendicular to the axis direction of the light introduction electrode. The range of the vacuum ultraviolet light emitted by the vacuum ultraviolet light source inside the light introduction electrode is the ionization zone. The region between the ionization zone and the outlet electrode constitutes the reaction zone. The sample gas flow q is regulated by the valve to change the ion movement speed v g in the gas flow field; or the voltage difference U applied to the light introduction electrode and the outlet electrode (i.e. the reaction zone) is regulated to change the ion movement speed v d in the electric field; the ion-molecule reaction time in the reaction zone is changed by changing v g and v d , so as to obtain the ion-molecule reaction process or regulate the ion-molecule reaction process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ion-molecule reactions, and particularly relates to a method for regulating ion-molecule reaction progress in a photoionization source. BACKGROUND

[0002] Ion-molecule reactions are an important class of reactions, and have played an important role in promoting the research of gas-phase chemistry.

[0003] By changing the time of ion-molecule reactions in the reaction zone, and combining the ion intensity and ion type measured by the mass analyzer, the ion type (species) and intensity (content) of ions at different reaction moments at the circular truncated cone-shaped through hole outside the ion source cavity and close to the exit electrode can be obtained, so that the ion-molecule reaction process or the regulation of the ion-molecule reaction progress can be known, the products of ion-molecule reactions at different stages can be obtained, and the understanding of the ion-molecule reaction mechanism can be deepened. SUMMARY

[0004] The present application provides a method for regulating ion-molecule reaction progress in a photoionization source.

[0005] To achieve the above object, the present application adopts the following technical scheme:

[0006] A method for regulating ion-molecule reaction progress in a photoionization source, which adopts a device comprising a photoionization source and a mass analyzer, wherein the photoionization source comprises a sample gas, a sample inlet pipeline, a valve A, a vacuum ultraviolet light source, an ion source cavity, an inlet electrode, a light introduction electrode, and an exit electrode.

[0007] The ion source cavity is a cylindrical structure with left and right open ends, a hollow circular ring-shaped light introduction electrode is arranged at the left open end of the ion source cavity, and a hollow insulating ring is arranged at the left open end of the light introduction electrode; the circular ring-shaped light introduction electrode and the insulating ring are coaxial with the ion source cavity, and the left and right side end faces of the circular ring-shaped light introduction electrode are in sealed connection with the right side end face of the insulating ring and the left open end of the ion source cavity, respectively.

[0008] The inlet electrode is arranged at the left open end of the insulating ring, and the exit electrode is arranged at the right open end of the ion source cavity.

[0009] The inlet electrode is a plate-shaped electrode with a gas inlet through hole in the middle, and serves as a repelling electrode, with the right side surface in sealed connection with the left side end face of the insulating ring.

[0010] The exit electrode is a plate-shaped electrode with a circular truncated cone-shaped through hole with a trapezoidal cross section in the middle, and is a vacuum differential electrode, with the circular truncated cone top surface (smaller side bottom surface) of the circular truncated cone-shaped through hole facing the inlet electrode, and the left side surface in sealed connection with the right open end of the ion source cavity.

[0011] The circular gas inlet hole of the inlet electrode and the circular frustum hole of the outlet electrode are coaxial with the cylindrical ionization source cavity;

[0012] A through hole for light inlet is formed on the sidewall (e.g., the upper sidewall) of the light introduction electrode in the radial direction, and the light emitted by the vacuum ultraviolet light source enters the area surrounded by the light introduction electrode in the radial direction of the light introduction electrode through the light inlet;

[0013] The sample gas outside the ionization source cavity is connected to the left end of the gas inlet hole in the middle of the inlet electrode through valve A;

[0014] A vacuum exhaust port is formed on the sidewall (e.g., the lower sidewall) of the ionization source cavity near the outlet electrode, and the vacuum exhaust port is connected to a vacuum pump through valve B to maintain the vacuum in the ionization source cavity;

[0015] A vacuum gauge is provided at the vacuum exhaust port to measure the gas pressure in the ionization source cavity;

[0016] A mass analyzer is provided outside the ionization source cavity near the circular frustum hole of the outlet electrode;

[0017] The sample gas flow rate q is adjusted through valve A to change the ion movement speed v in the gas flow field g , or the voltage difference U between the light introduction electrode and the outlet electrode (i.e., the reaction zone) is adjusted to change the ion movement speed v in the electric field d , and the ion molecular reaction time in the reaction zone is changed g or v d ,

[0018] By changing the ion molecular reaction time in the reaction zone, the ion intensity and ion type measured by the mass analyzer can be obtained, and the ion type (species) and intensity (content) of the ion at different reaction times near the circular frustum hole of the outlet electrode outside the ionization source cavity can be obtained, so as to obtain the ion molecular reaction process or control the ion molecular reaction process.

[0019] Further, in the above technical solution, the calculation formula of the ion molecular reaction time t in the reaction zone is

[0020]

[0021] q is the sample gas 1 flow rate at atmospheric pressure p0;

[0022] r is the inner radius of the ionization source cavity 5;

[0023] p is the gas pressure in the ionization source cavity 5, p0 = 760 Torr;

[0024] U is the voltage difference between the light introduction electrode 7 and the outlet electrode 13.

[0025] T is the temperature in the ionization source cavity 5, T0 = 273 K;

[0026] d is the distance between the left and right, light introduction electrode and outlet electrode (the length of the reaction zone from left to right);

[0027] K is the ion mobility; K0 is the reduced mobility at a temperature of 273 K and a gas pressure of 760 Torr.

[0028] Further, in the above technical solution, the exit light of the vacuum ultraviolet light source is perpendicular to the axis direction of the light introduction electrode, and the range of the vacuum ultraviolet light emitted by the vacuum ultraviolet light source inside the light introduction electrode is the ionization zone; the region between the ionization zone and the outlet electrode constitutes the reaction zone; along the direction of the ionization source cavity axis, the width range of the ionization zone is 0.1-4 mm (the length from left to right);

[0029] The inlet electrode and the outlet electrode are parallel plate structures; the central through hole of the inlet electrode and the outlet electrode are coaxial with the light introduction electrode.

[0030] Further, in the above technical solution, the sample gas injection amount q at atmospheric pressure controlled by the valve A is 5-500 mL / min, and the adjustment range of the injection amount q is 5-300 mL / min;

[0031] The inner radius r of the ionization source cavity is 0.1-10 cm; the gas pressure p of the ionization source cavity ranges from 0.1 to 760 Torr; the temperature T of the ionization source cavity ranges from 273 to 500 K;

[0032] The length d of the reaction zone (in the direction of the ionization source cavity axis) is 0.5-50 cm.

[0033] Further, in the above technical solution, the voltage difference U applied to the light introduction electrode and the outlet electrode ranges from 0.1 to 500 V, and the step (i.e. the adjustment range of the voltage difference U) is 0.1-10 V;

[0034] The reduced mobility K0 at a temperature of 273 K and a gas pressure of 760 Torr can be estimated as (2.0±0.2) cm 2 V -1 s -1 ;

[0035] According to the formula, the ion-molecule reaction time t can be calculated to be in the range of 1 μs-1 s.

[0036] Further, in the technical solution, the sample gas contains carrier gas, a substance that can be ionized by the vacuum ultraviolet light source, and molecules that can have ion-molecule reactions with the ions generated by ionization of the substance; the concentration of the substance that can be ionized by the vacuum ultraviolet light source in the carrier gas is 10 2 -10 5 ppmv; the concentration of the molecules that can have ion-molecule reactions with the ions generated by ionization of the substance in the carrier gas is 10 1 -10 5 ppmv.

[0037] The carrier gas is one or more of air, nitrogen, helium, and argon.

[0038] Further, in the technical solution, the substance that can be ionized by the vacuum ultraviolet light source is one or more of dichloromethane, dibromomethane, acetone, toluene, and anisole.

[0039] The molecules that can have ion-molecule reactions with the ions generated by ionization of the substance are one or more of water, methanol, ethanol, formaldehyde, and acetaldehyde.

[0040] Further, in the technical solution, the vacuum ultraviolet light source is a gas discharge lamp, an ultraviolet light-emitting diode, a synchrotron radiation source, or a laser light source.

[0041] The valves A and B are each one of a needle valve, a ball valve, a flapper valve, and a butterfly valve.

[0042] The sample ions flow out of the conical frustum-shaped through hole of the exit electrode and enter the mass analyzer for detection.

[0043] The mass analyzer is at least one of a magnetic mass analyzer, a quadrupole mass analyzer, an ion trap mass analyzer, a time-of-flight (TOF) mass analyzer, a Fourier transform ion cyclotron resonance (FT-ICR) mass analyzer, and an electrostatic field orbitrap mass analyzer.

[0044] Further, in the technical solution, the light exit port of the vacuum ultraviolet light source is in airtight connection with the outer sidewall of the light introduction electrode.

[0045] The ionization source cavity is a cylinder made of insulating material.

[0046] Further, in the technical solution, the inner diameter of the ring-shaped light introduction electrode and the inner diameter of the insulating ring are each equal to the inner diameter of the ionization source cavity.

[0047] Advantages

[0048] The present application can regulate the time and process of ion-molecule reactions, obtain products at different stages of ion-molecule reactions, and thus deepen the understanding of the mechanism of ion-molecule reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings further illustrate the present invention, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0050] Figure 1 The invention relates to a method for regulating the reaction process of ions and molecules in a photoionization source.

[0051] In the figure, 1. sample gas; 2. sampling line; 3. valve A; 4. vacuum ultraviolet light source; 5. ionization source cavity; 6. inlet electrode; 7. light introduction electrode; 8. ionization zone; 9. reaction zone; 10. valve B; 11. vacuum pump; 12. vacuum gauge; 13. outlet electrode; 14. mass analyzer.

[0052] Figure 2 This is the result of the ion-molecule reaction between the dichloromethane photoionization product ion CH2Cl+ and water. DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to specific embodiments.

[0054] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0055] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0056] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0057] The foregoing description, for purposes of explanation, only is exemplary and not limitative. There can be many modifications, variations and alternatives, and the embodiments disclosed herein are not the only ones that accomplish the disclosed examples. The specific embodiments were chosen and described in order to best explain the principles of operation and the best mode of utilising them. The use of certain terms in various places of this disclosure is only for the purpose of reference and does not imply a limitation on the claims. For example, it is clear that the singular also includes the plural unless indicated otherwise. It is also clear that "comprising" is inclusive and not exclusive, that is, that compositions comprising elements other than those listed are also contemplated. It has been noted that the use of certain terms, for example, "above" and "below", "up" and "down", and "top" and "bottom", are used for clarity's sake. None of the terms is intended to create a "critical plane" such that structures built in one plane can not be in another. It is clear that relative positional terms are intended to encompass different positional relationships to other parts.

[0058] In the description of the application, it is to be understood that the orientation or positional relationships indicated by terms such as "front", "back", "upper", "lower", "left", "right", "horizontal", "vertical", "top", "bottom", and the like are generally based on the orientation or positional relationships shown in the drawings and are merely for convenience of description and do not imply that the device or element must be in a particular orientation or constructed and operated in a particular orientation, and therefore cannot be construed as a limitation on the scope of protection of the present application. The orientation terms "inner" and "outer" refer to the inner and outer sides relative to the outline of the respective components.

[0059] Example 1

[0060] Referring to Figure 1 A method for regulating the reaction process of ion molecules in a photoionization source, the device comprises a photoionization source and a mass analyzer 14, the photoionization source comprises a sample gas 1, a sample inlet pipeline 2, a valve A 3, a vacuum ultraviolet light source 4, an ionization source cavity 5, an inlet electrode 6, a light introduction electrode 7, and an outlet electrode 13.

[0061] The ionization source cavity 5 is a cylindrical structure with left and right open ends. A hollow annular light introduction electrode 7 is arranged at the left open end of the ionization source cavity 5. An insulating ring is arranged at the left open end of the light introduction electrode 7. The annular light introduction electrode 7 and the insulating ring are coaxial with the ionization source cavity 5, and the left and right side end faces of the annular light introduction electrode 7 are in sealed connection with the right side end face of the insulating ring and the left open end of the ionization source cavity 5, respectively.

[0062] The inlet electrode 6 is a plate-shaped electrode with a gas inlet through hole in the middle, which is used as a repelling electrode and is in sealed connection with the left side end face of the insulating ring.

[0063] The inlet electrode 6 is a plate-shaped electrode with a gas inlet through hole in the middle, which is used as a repelling electrode and is in sealed connection with the left side end face of the insulating ring.

[0064] The exit electrode 13 is a plate-shaped electrode with a truncated cone-shaped through hole with a trapezoidal axial cross-section in the middle. It is a vacuum differential electrode. The upper bottom surface of the truncated cone-shaped through hole (the bottom surface on the side with a smaller area) faces the entrance electrode 6, and its left side surface is sealed and connected to the right open end of the ionization source chamber 5.

[0065] The circular air inlet through hole of the entrance electrode 6 and the truncated cone-shaped through hole of the exit electrode 13 are coaxial with the cylindrical ionization source cavity 5;

[0066] A through hole is provided in the radial direction on the upper side wall of the light introduction electrode 7 as a light inlet. The light emitted by the vacuum ultraviolet light source 4 passes through the light inlet and is incident in the radial direction of the light introduction electrode 7 into the area surrounded by the light introduction electrode 7.

[0067] The sample gas 1 outside the ionization source cavity 5 is connected to the left end of the gas inlet hole in the middle of the entrance electrode 6 through the valve A3;

[0068] A vacuum pumping port is provided on the lower side wall of the ionization source chamber 5 near the outlet electrode. The vacuum pumping port is connected to an external vacuum pump 11 through a valve B10 to maintain the vacuum in the ionization source chamber 5.

[0069] A vacuum gauge 12 is provided at the vacuum pumping port for measuring the air pressure in the ionization source cavity 5;

[0070] A mass analyzer 14 is provided outside the ionization source cavity 5 and near the truncated cone-shaped through hole of the exit electrode 13;

[0071] The light emitted by the vacuum ultraviolet light source 4 is perpendicular to the axis of the light introduction electrode 7. The range of the vacuum ultraviolet light emitted by the vacuum ultraviolet light source 4 inside the light introduction electrode 7 is the ionization zone 8. The area between the ionization zone 8 and the outlet electrode 13 constitutes the reaction zone 9.

[0072] The injection volume q of the sample gas 1 is adjusted by valve A3 to change the movement speed v of the ions in the air flow field. g Or by adjusting the voltage difference U applied between the light introduction electrode 7 and the outlet electrode 13 (ie, the reaction zone 9), changing the movement speed v of the ions in the electric field d By changing v g or v d The time of ion-molecule reaction in the reaction zone 9 can be changed.

[0073] By changing the time of the ion-molecule reaction in the reaction zone 9 and combining the ion intensity and ion type measured by the mass analyzer 14, the ion type (type) and intensity (content) of the ions at different reaction times at the conical through hole outside the ion source cavity near the exit electrode 13 can be obtained, thereby knowing the process of the ion-molecule reaction or regulating the progress of the ion-molecule reaction.

[0074] The time t of the ion-molecule reaction in the reaction zone 9 is calculated by the formula:

[0075]

[0076] q is the sample gas 1 injection amount at atmospheric pressure p0;

[0077] r is the inner radius of the ion source cavity 5;

[0078] p is the gas pressure in the ion source cavity 5, p0=760 Torr;

[0079] U is the voltage difference between the light introduction electrode 7 and the exit electrode 13;

[0080] T is the temperature in the ion source cavity 5, T0=273 K;

[0081] d is the distance between the light introduction electrode 7 and the exit electrode 13 from left to right (the length of the reaction zone 9 from left to right);

[0082] K is the ion mobility; K0 is the reduced mobility at a temperature of 273 K and a gas pressure of 760 Torr.

[0083] The width of the ionization zone 8 along the axis of the ion source cavity 5 is in the range of 2 mm (length from left to right);

[0084] The inlet electrode 6 and the exit electrode 13 are parallel plate structures; the central through hole of the inlet electrode 6 and the exit electrode 13 are coaxial with the light introduction electrode 7.

[0085] The light outlet of the vacuum ultraviolet light source 4 is in airtight connection with the outer side wall of the light introduction electrode 7;

[0086] The ion source cavity 5 is a cylinder made of insulating material.

[0087] The inner diameter of the circular ring-shaped light introduction electrode 7 and the inner diameter of the insulating ring are both equal to the inner diameter of the ion source cavity 5.

[0088] As one of the embodiments, the vacuum ultraviolet light source 4 is a gas discharge lamp, specifically a vacuum ultraviolet krypton lamp.

[0089] As one of the embodiments, the valve A3 is a needle valve and the valve B10 is a baffle valve.

[0090] The sample ions flow out of the conical frustum-shaped through hole of the exit electrode 13 and enter the mass analyzer 14 for detection;

[0091] As one of the embodiments, the mass analyzer is a time-of-flight (TOF) mass analyzer.

[0092] As one of the embodiments, the sample gas 1 is introduced at a constant rate q of 180 mL / min at atmospheric pressure by regulating the valve B (needle valve).

[0093] As one of the embodiments, the sample gas 1 is a mixture of 3000 ppmv dichloromethane (gas) and 400 ppmv water (gas), and the carrier gas is high-purity helium (99.999%). The dichloromethane (CH2Cl2) can be ionized into CH2Cl + ions by the vacuum ultraviolet light source 4. + The ions can have ion-molecule reactions with H2O molecules.

[0094] As one of the embodiments, the inner radius r of the ion source cavity 5 is 0.7 cm, the gas pressure p in the ion source cavity 5 is 3.76 Torr, and the temperature T in the ion source cavity 5 is 323 K. The gas flow velocity v g = 395 cm / s can be calculated.

[0095] As one of the embodiments, the length d of the reaction zone 9 (the distance between the light introduction electrode 7 and the exit electrode 13 from left to right) is 1 cm.

[0096] By adjusting the voltage applied to the light introduction electrode 7 and the exit electrode 13, the voltage difference U of the reaction zone 9 ranges from 0.3 V to 90.9 V, as shown in Table 1, the ion movement speed v d in the electric field can be changed, the ion-molecule reaction time in the reaction zone 9 is regulated, and thus the progress of the ion-molecule reaction is regulated.

[0097] The reduced mobility K0 at a temperature of 273 K and a gas pressure of 760 Torr can be estimated to be (2.0 ± 0.2) cm 2 V -1 s -1 ;

[0098] Table 1

[0099]

[0100] The voltage difference U of the reaction zone 9 ranges from 0.3 V to 90.9 V, and the ion-molecule reaction time t is calculated to range from 0.02 ms to 1.89 ms according to the above parameters, as shown in Figure 2 and Table 1. The specific calculation process for U = 2.3 V is given below, and the calculation method for other values is the same.

[0101]

[0102] It can be known from Figure 2 that the photoionization product ion CH2Cl +ion-molecule reaction with water, i.e. CH2Cl + intermediate ion CH2OH + intermediate ion CH2OH + further reaction with water to form water ion H3O + The reaction equation is as follows:

[0103] CH2Cl + + H2O → CH2OH + + HCl

[0104] CH2OH + + H2O → H3O + + CH2O

[0105] ion-molecule reaction with water, i.e. CH2Cl + ion-molecule reaction with water, i.e. CH2Cl + ion-molecule reaction with water, i.e. CH2Cl + .

[0106] Example 2

[0107] The process and conditions are the same as in Example 1, except that:

[0108] The voltage difference (i.e. the reaction zone 9) U applied on the light introduction electrode 7 and the outlet electrode 13 is fixed at 2.3V; the sample gas 1 is introduced at an atmospheric pressure with a flow rate q of 5-500 mL / min, which changes the ion movement speed v in the gas flow field g The ion-molecule reaction time in the reaction zone 9 is regulated, so as to regulate the ion-molecule reaction process. See Table 2 for details.

[0109] Table 2

[0110]

[0111] The technical principles of the present application are described above in combination with specific examples. These descriptions are only for explaining the principles of the present application, and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanations herein, other specific embodiments of the present application can be conceived by those skilled in the art without any creative effort, and these equivalent variations or replacements are all included in the scope defined by the claims of the present application.

[0112] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for regulating the progress of ion-molecule reactions in a photoionization source, characterized in that: The device comprises a photoionization source and a mass analyzer (14), wherein the photoionization source comprises a sample gas (1), a sample inlet line (2), a valve A (3), a vacuum ultraviolet light source (4), an ionization source cavity (5), an inlet electrode (6), a light introduction electrode (7), and an outlet electrode (13); The ionization source cavity (5) is a cylindrical structure with left and right ends open. A hollow annular light introduction electrode (7) is provided at the left open end of the ionization source cavity (5). A hollow insulating ring is provided at the left open end of the light introduction electrode (7). The annular light introduction electrode (7) and the insulating ring are coaxial with the ionization source cavity (5), and the left and right end faces of the annular light introduction electrode (7) are respectively sealed and connected to the right end face of the insulating ring and the left open end of the ionization source cavity (5). An entrance electrode (6) is provided on the left end surface of the insulating ring; an exit electrode (13) is provided on the right open end of the ionization source cavity (5); The inlet electrode (6) is a plate-shaped electrode with a circular air inlet hole in the middle, serving as a repelling electrode, and its right side surface is tightly connected to the left end face of the insulating ring; The outlet electrode (13) is a plate-shaped electrode with a truncated cone-shaped through hole with a trapezoidal axial cross section in the middle, and is a vacuum differential electrode. The upper bottom surface of the truncated cone-shaped through hole faces the inlet electrode (6), and the left side surface is sealed and connected to the right open end of the ionization source cavity (5); The circular air inlet through hole of the inlet electrode (6) and the truncated cone-shaped through hole of the outlet electrode (13) are both coaxial with the cylindrical ionization source cavity (5); A through hole serving as a light inlet is provided in a radial direction on a side wall surface of the light introduction electrode (7), and light emitted from the vacuum ultraviolet light source (4) passes through the light inlet and is incident in a radial direction of the light introduction electrode (7) into an area surrounded by the light introduction electrode (7); The sample gas (1) outside the ionization source cavity (5) is connected to the left open end of the circular gas inlet hole in the middle of the inlet electrode (6) through the valve A (3); A vacuum pumping port is provided on the side wall of the ionization source cavity (5) near the outlet electrode, and the vacuum pumping port is connected to an external vacuum pump (11) via a valve B (10) for maintaining the vacuum in the ionization source cavity (5); A vacuum gauge (12) for measuring the air pressure in the ionization source cavity (5) is provided at the vacuum pumping port; A mass analyzer (14) is provided outside the ionization source cavity (5) and at a truncated cone-shaped through hole close to the exit electrode (13); The light emitted by the vacuum ultraviolet light source (4) is perpendicular to the axis direction of the light introduction electrode (7). The range of the vacuum ultraviolet light emitted by the vacuum ultraviolet light source (4) inside the light introduction electrode (7) is the ionization zone (8). The area between the ionization zone (8) and the outlet electrode (13) constitutes the reaction zone (9). The injection volume of the sample gas (1) is adjusted by valve A (3) q , changing the speed of ions in the air flow field v g or by adjusting the voltage difference applied between the light introduction electrode (7) and the exit electrode (13), i.e., the reaction zone (9) U , changing the speed of ions in the electric field v d By changing v g or v d The time of the ion-molecule reaction in the reaction zone (9) can be changed. By changing the time of the ion-molecule reaction in the reaction zone (9), combined with the ion intensity and ion type measured by the mass analyzer (14), the ion type and intensity of the ions at different reaction times at the truncated cone-shaped through hole outside the ion source cavity and close to the exit electrode (13) can be obtained, thereby knowing the process of the ion-molecule reaction or regulating the progress of the ion-molecule reaction.

2. The method according to claim 1, wherein: The calculation formula for the time t of the ion-molecule reaction in the reaction zone (9) is: ； ； ； K is the ion mobility, K 0 is the reduced mobility at a temperature of 273 K and a pressure of 760 Torr; E The electric field strength between the light introduction electrode (7) and the exit electrode (13), i.e., the reaction zone (9); U The voltage difference between the light introduction electrode (7) and the exit electrode (13), i.e., the reaction zone (9); d The distance from left to right between the light introduction electrode (7) and the exit electrode (13) is the length of the reaction zone (9) from left to right; T is the temperature inside the ionization source cavity (5), T 0 = 273 K; p is the gas pressure in the ionization source cavity (5), p 0 = 760 Torr; q For the sample gas (1) at atmospheric pressure p The injection volume at 0; r is the inner radius of the ionization source cavity (5).

3. The method according to claim 1 or 2, characterized in that: Along the axis of the ionization source cavity (5), the width of the ionization region (8) ranges from 0.1 to 4 mm; The inlet electrode (6) and the outlet electrode (13) are parallel plate-type structures; the central through holes of the inlet electrode (6) and the outlet electrode (13) are coaxial with the light introduction electrode (7).

4. The method according to claim 1 or 2, characterized in that: The injection amount of the sample gas (1) at atmospheric pressure is controlled by the valve A (3) q 5-500 mL / min, injection volume q The adjustment range is 5-300 mL / min; The inner radius of the ionization source cavity (5) r 0.1-10 cm; the pressure of the ionization source cavity (5) p The range is 0.1-760Torr; the temperature of the ionization source cavity (5) T The range is 273-500 K; The length of the reaction zone (9) along the axis of the ionization source cavity (5) d 0.5-50 cm.

5. The method according to claim 1 or 2, characterized in that: The voltage difference applied to the light introduction electrode (7) and the exit electrode (13) U The range is 0.1-500 V, and the step size is the voltage difference U The adjustment range is 0.1-10 V; Ion-molecule reaction time t The range is 1 μs-1 s.

6. The method according to claim 1 or 2, characterized in that: The sample gas contains a carrier gas, a substance that can be ionized by the vacuum ultraviolet light source (4), and a molecule that can react with the ions generated by the ionization of the substance; the concentration of the substance that can be ionized by the vacuum ultraviolet light source (4) in the carrier gas is 10 2 -10 5 ppmv; the concentration of molecules in the carrier gas that can react with the ions produced by the ionization of the substance is 10 1 -10 5 ppmv; The carrier gas is one or more of air, nitrogen, helium, and argon.

7. The method according to claim 6, characterized in that: The substance that can be ionized by the vacuum ultraviolet light source (4) is one or more of dichloromethane, dibromomethane, acetone, toluene, and anisole; The molecules capable of undergoing ion-molecule reaction with the ions generated by ionization of the substance are one or more of water, methanol, ethanol, formaldehyde, and acetaldehyde.

8. The method according to claim 1, wherein: The vacuum ultraviolet light source (4) is one or more of a gas discharge lamp, an ultraviolet light emitting diode, a synchrotron radiation light source or a laser light source; The valve A (3) and valve B (10) are respectively one or more of a needle valve, a ball valve, a baffle valve, and a butterfly valve; The sample ions flow out from the truncated cone-shaped through hole of the outlet electrode (13) and enter the mass analyzer (14) for detection; The mass analyzer (14) is at least one or more of a magnetic mass analyzer, a quadrupole mass analyzer, an ion trap mass analyzer, a time-of-flight (TOF) mass analyzer, a Fourier transform ion cyclotron resonance (FT-ICR) mass analyzer, and an electrostatic field orbitrap (Orbitrap) mass analyzer.

9. The method according to claim 1, wherein: The edges around the light outlet of the vacuum ultraviolet light source (4) are tightly connected to the outer wall of the light introduction electrode (7); The ionization source cavity (5) is a cylinder made of insulating material.

10. The method according to claim 1, wherein: The inner diameter of the annular light introduction electrode (7) and the inner diameter of the insulating ring are both equal to the inner diameter of the ionization source cavity (5).

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