Method for regulating and controlling reaction process of ions and molecules in photo ionization source

Abstract

The invention relates to a method for regulating and controlling the reaction process of ions and molecules in a photo ionization source. Comprising a sample gas, a sample introduction 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. Emergent light of the vacuum ultraviolet light source is perpendicular to the axis direction of the light introduction electrode, the irradiation range of the vacuum ultraviolet light emitted by the vacuum ultraviolet light source in the light introduction electrode is an ionization area, and an area between the ionization area and the outlet electrode forms a reaction area. The sample size q of the sample gas is adjusted through a valve, and the movement speed vg of ions in the gas flow field is changed; or the movement speed vd of the ions in the electric field is changed by adjusting the voltage difference U applied to the light leading-in electrode and the light outlet electrode (namely the reaction area); the time of the ion molecule reaction in the reaction zone can be changed by changing the vg and the vd, so that the process of the ion molecule reaction is known or the process of the ion molecule reaction is regulated and controlled.

Description

Technical Field

[0001] The invention belongs to the field of ion-molecule reaction, and in particular relates to a method for regulating the process of ion-molecule reaction in a photoionization source. Background Art

[0002] Ion-molecule reactions are an important type of reaction and have played a significant role in promoting the research of gas-phase chemistry.

[0003] The present invention changes the time of ion-molecule reaction in the reaction zone, and in combination with the ion intensity and ion type measured by the mass analyzer, can obtain the ion type (type) and intensity (content) of ions at different reaction times at the truncated cone-shaped through hole outside the ion source cavity and close to the exit electrode, thereby knowing the history of the ion-molecule reaction or regulating the progress of the ion-molecule reaction, obtaining the products of the ion-molecule reaction at different stages, and deepening the understanding of the mechanism of the ion-molecule reaction. Summary of the invention

[0004] The invention provides a method for regulating the reaction process of ions and molecules in a photoionization source.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for regulating the ion-molecule reaction process in a photoionization source, using a device including a photoionization source and a mass analyzer, wherein the photoionization source includes a sample gas, a sample injection pipeline, a valve A, a vacuum ultraviolet light source, an ionization source cavity, an inlet electrode, a light introduction electrode, and an outlet electrode;

[0007] The ionization source cavity is a cylindrical structure with left and right ends open. A hollow annular light introduction electrode is provided at the left open end of the ionization source cavity, and a hollow insulating ring is provided at the left open end of the light introduction electrode. The annular light introduction electrode and the insulating ring are coaxial with the ionization source cavity, respectively, and the left and right side end faces of the annular light introduction electrode are respectively sealed and connected with the right side end face of the insulating ring and the left open end of the ionization source cavity.

[0008] An inlet electrode is provided at the left open end of the insulating ring; an outlet electrode is provided at the right open end of the ionization source cavity;

[0009] The inlet electrode is a plate-shaped electrode with an air inlet hole in the middle, serving as a repelling electrode, and its right side surface is tightly connected to the left end surface of the insulating ring;

[0010] The exit electrode is a plate-shaped electrode with a truncated cone-shaped through hole with a trapezoidal axial section in the middle, and 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, and the left side surface is tightly connected to the right open end of the ionization source cavity.

[0011] The circular air inlet through hole of the entrance electrode and the truncated cone-shaped through hole of the exit electrode are coaxial with the cylindrical ionization source cavity;

[0012] A through hole serving as a light inlet is radially provided on a side wall surface (e.g., an upper side wall) of the light introduction electrode, and an outgoing light beam from a vacuum ultraviolet light source passes through the light inlet and is incident along a radial direction of the light introduction electrode into an area surrounded by the light introduction electrode;

[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 entrance electrode through valve A;

[0014] A vacuum pumping port is provided on the side wall surface (e.g., lower side wall) of the ionization source cavity near the exit electrode, and the vacuum pumping port is connected to an external vacuum pump through valve B to maintain the vacuum in the ionization source cavity;

[0015] A vacuum gauge for measuring the air pressure in the ionization source cavity is provided at the vacuum pumping port;

[0016] A mass analyzer is provided outside the ionization source cavity and at a truncated cone-shaped through hole close to the exit electrode;

[0017] The injection volume q of the sample gas is adjusted by valve A to change the movement speed v of the ions in the gas flow field. g ; or by adjusting the voltage difference U applied to the light introduction electrode and the exit electrode (i.e., the reaction zone), changing the movement speed v of the ions in the electric field d ; By changing v g and v d The reaction time of ions and molecules in the reaction zone can be changed.

[0018] By changing the time of the ion-molecule reaction in the reaction zone and combining it with the ion intensity and ion type measured by the mass analyzer, the ion type (type) and intensity (content) of ions at different reaction times at the conical through hole outside the ion source cavity near the exit electrode can be obtained, thereby knowing the course of the ion-molecule reaction or regulating the progress of the ion-molecule reaction.

[0019] Furthermore, in the above technical solution, the calculation formula for the time t of the ion-molecule reaction in the reaction zone is,

[0020]

[0021]

[0022]

[0023] q is the injection volume of sample gas at atmospheric pressure;

[0024] r is the inner radius of the ionization source cavity;

[0025] p is the gas pressure in the ionization source cavity;

[0026] U is the voltage difference between the light introduction electrode and the exit electrode;

[0027] T is the temperature in the ionization source cavity;

[0028] d is the distance from left to right between the light introduction electrode and the exit electrode (the length of the reaction zone from left to right);

[0029] K is the ion mobility; K0 is the reduced mobility at a temperature of 273 K and a pressure of 760 Torr.

[0030] Furthermore, in the above technical solution, the light emitted by the vacuum ultraviolet light source is perpendicular to the axial 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, and the area between the ionization zone and the exit electrode constitutes the reaction zone; along the direction of the ionization source cavity axis, the width of the ionization zone ranges from 0.1 to 4 mm (length from left to right);

[0031] The inlet electrode and the outlet electrode are parallel plate structures; the middle through holes of the inlet electrode and the outlet electrode are coaxial with the light introduction electrode.

[0032] Further, in the above technical solution, the injection volume q of the sample gas at atmospheric pressure is controlled by the valve to be 5-500 mL / min, and the adjustment range of the injection volume q is 5-300 mL / min;

[0033] The inner radius r of the ionization source cavity is 0.1-10 cm; the gas pressure p of the ionization source cavity is in the range of 0.1-760 Torr; the temperature T of the ionization source cavity is in the range of 273-500K;

[0034] The length d of the reaction zone (along the axis of the ionization source cavity) is 0.5-50 cm.

[0035] Further, in the above technical solution, the voltage difference U applied to the light introduction electrode and the exit electrode ranges from 0.1 to 500 V, and the step length (i.e., the adjustment amplitude of the voltage difference U) is 0.1 to 10 V;

[0036] The reduced mobility K0 at 273K and 760Torr can be estimated to be (2.0±0.2)cm 2 V -1 s -1 ;

[0037] According to the formula in claim 1, it can be calculated that the range of the ion-molecule reaction time t is 1 μs-1s.

[0038] Furthermore, in the above technical solution, the sample gas contains a carrier gas, a substance that can be ionized by a vacuum ultraviolet light source, 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 a vacuum ultraviolet light source in the carrier gas is 10 2 -10 5 ppmv; the concentration of molecules in the carrier gas that can react with the ions of the substance is 10 1 -10 5 ppmv;

[0039] The carrier gas is one or more of air, nitrogen, helium and argon.

[0040] Furthermore, in the above 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;

[0041] 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.

[0042] Furthermore, in the above technical solution, the vacuum ultraviolet light source is a gas discharge lamp, an ultraviolet light emitting diode, a synchrotron radiation light source or a laser light source;

[0043] The valve A and valve B are respectively one of a needle valve, a ball valve, a baffle valve, and a butterfly valve;

[0044] The sample ions flow out from the truncated cone-shaped through hole of the exit electrode and enter the mass analyzer for detection;

[0045] 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 (Orbitrap) mass analyzer.

[0046] Furthermore, in the above technical solution, the edges around the light outlet of the vacuum ultraviolet light source are tightly connected to the outer wall surface of the light introduction electrode;

[0047] The ionization source cavity is a cylinder made of insulating material.

[0048] Furthermore, in the above technical solution, the inner diameter of the annular light introduction electrode and the inner diameter of the insulating ring are respectively equal to the inner diameter of the ionization source cavity.

[0049] Beneficial Effects

[0050] The present invention regulates the time and process of the ion-molecule reaction, and can obtain the products of the ion-molecule reaction at different stages, thereby deepening the understanding of the ion-molecule reaction mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The accompanying drawings further illustrate the present invention, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0052] Figure 1 The invention discloses a method for regulating the reaction process of ions and molecules in a photoionization source.

[0053] In the figure, 1. sample gas; 2. injection pipeline; 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.

[0054] Figure 2 This is the result of the ion-molecule reaction between the dichloromethane photoionization product ion CH2Cl+ and water. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with specific embodiments.

[0056] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments 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.

[0057] 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 by no means 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 creative work are within the scope of protection of the present invention.

[0058] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0059] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0060] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0061] Example 1

[0062] See also Figure 1 , which is a method for regulating the ion-molecule reaction process in a photoionization source of the present invention, the device includes a photoionization source and a mass analyzer 14, the photoionization source includes a sample gas 1, a sample injection pipeline 2, a valve A3, 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;

[0063] The ionization source cavity 5 is a cylindrical structure with left and right ends opened. A hollow annular light introduction electrode 7 is provided at the left open end of the ionization source cavity 5, and 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, respectively, and the left and right side end faces of the annular light introduction electrode 7 are respectively sealed and connected with the right side end face of the insulating ring and the left open end of the ionization source cavity 5;

[0064] An entrance electrode 6 is provided at the left opening end of the insulating ring; an exit electrode 13 is provided at the right opening end of the ionization source cavity 5;

[0065] The inlet electrode 6 is a plate-shaped electrode with an air inlet hole in the middle, serving as a repelling electrode, and its right side surface is tightly connected to the left end surface of the insulating ring;

[0066] The exit electrode 13 is a plate-shaped electrode with a truncated cone-shaped through hole with a trapezoidal axial section in the middle, and is a vacuum differential electrode. The upper bottom surface of the truncated cone of the truncated cone-shaped through hole (the bottom surface on the side with a smaller area) faces the entrance electrode 6, and the left side surface is sealed and connected to the right open end of the ionization source cavity 5;

[0067] 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;

[0068] A through hole is provided in the radial direction on the upper side wall of the light introduction electrode 7 as a light entrance, and the light emitted by the vacuum ultraviolet light source 4 passes through the light entrance and is incident in the radial direction of the light introduction electrode 7 into the area surrounded by the light introduction electrode 7;

[0069] 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;

[0070] A vacuum pumping port is provided on the lower wall of the ionization source cavity 5 near the exit electrode, and the vacuum pumping port is connected to an external vacuum pump 11 through a valve B10 to maintain the vacuum in the ionization source cavity 5;

[0071] A vacuum gauge 12 for measuring the air pressure in the ionization source cavity 5 is provided at the vacuum exhaust port;

[0072] 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;

[0073] The light emitted by the vacuum ultraviolet light source 4 is perpendicular to the axial 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.

[0074] 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 gas flow field. g or by adjusting the voltage difference U applied to 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 and v d The time of the ion-molecule reaction in the reaction zone 9 can be changed.

[0075] 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 course of the ion-molecule reaction or regulating the progress of the ion-molecule reaction.

[0076] The calculation formula for the time t of the ion-molecule reaction in the reaction zone 9 is:

[0077]

[0078]

[0079]

[0080] q is the injection volume of sample gas 1 at atmospheric pressure;

[0081] r is the inner radius of the ionization source cavity 5;

[0082] p is the gas pressure in the ionization source cavity 5;

[0083] U is the voltage difference between the light introduction electrode 7 and the exit electrode 13;

[0084] T is the temperature in the ionization source cavity 5;

[0085] d is the distance from left to right between the light introduction electrode 7 and the exit electrode 13 (the length of the reaction zone 9 from left to right);

[0086] K is the ion mobility; K0 is the reduced mobility at a temperature of 273 K and a pressure of 760 Torr.

[0087] Along the axis of the ionization source cavity 5, the width of the ionization region 8 is 2 mm (length from left to right);

[0088] The inlet electrode 6 and the outlet electrode 13 are parallel plate structures; the middle through holes of the inlet electrode 6 and the outlet electrode 13 are coaxial with the light introduction electrode 7 .

[0089] 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;

[0090] The ionization source cavity 5 is a cylinder made of insulating material.

[0091] The inner diameter of the annular light introduction electrode 7 and the inner diameter of the insulating ring are respectively equal to the inner diameter of the ionization source cavity 5 .

[0092] As one of the embodiments, the vacuum ultraviolet light source 4 is a gas discharge lamp, specifically a vacuum ultraviolet krypton lamp.

[0093] As one of the embodiments, the valve A3 is a needle valve, and the valve B10 is a flapper valve.

[0094] The sample ions flow out from the truncated cone-shaped through hole of the exit electrode 13 and enter the mass analyzer 14 for detection;

[0095] As one embodiment, the mass analyzer is a time-of-flight (TOF) mass analyzer.

[0096] As one of the embodiments, the injection volume q of the sample gas 1 at atmospheric pressure is adjusted to a constant 180 mL / min by valve B (needle valve).

[0097] As one of the embodiments, the composition of 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%). Dichloromethane (CH2Cl2) can be ionized into CH2Cl2 by the vacuum ultraviolet light source 4. + Ion, CH2Cl + The ions can react with H2O molecules in an ion-molecule reaction.

[0098] As one of the embodiments, the inner radius r of the ionization source cavity 5 is 0.7 cm, the air pressure p in the ionization source cavity 5 is 3.76 Torr, and the temperature T in the ionization source cavity 5 is 323 K; the air flow velocity v can be calculated. g =395cm / s.

[0099] As one of the embodiments, the length d of the reaction zone 9 (the distance from left to right between the light introduction electrode 7 and the exit electrode 13) is 1 cm.

[0100] By adjusting the voltage applied to the light introduction electrode 7 and the outlet electrode 13, the voltage difference U in the reaction zone 9 is in the range of 0.3V-90.9V, as shown in Table 1, and the movement speed v of the ions in the electric field can be changed. d , regulating the ion-molecule reaction time in the reaction zone 9, thereby regulating the progress of the ion-molecule reaction.

[0101] The reduced mobility K0 at 273K and 760Torr can be estimated to be (2.0±0.2)cm 2 V -1 s -1 ;

[0102] Table 1

[0103]

[0104] The voltage difference U of the reaction zone 9 ranges from 0.3V to 90.9V. Based on the above parameters, the ion molecule reaction time t ranges from 0.02ms to 1.89ms. Figure 2 and Table 1. The specific calculation process when U = 2.3V is given below, and the other calculation methods are the same.

[0105]

[0106] Depend on Figure 2 It can be known that the product ion of dichloromethane photoionization is CH2Cl + The process of the reaction between ion molecules and water, namely CH2Cl + Reacts with water to form the intermediate product ion CH2OH + , the intermediate product ion CH2OH + Further react with water to form water ions H3O + , the reaction equation is as follows:

[0107] CH2Cl + +H2O→CH2OH + +HCl

[0108] CH2OH + +H2O→H3O + +CH2O

[0109] CH2Cl + It reacts with H2O to form CH2OH + Finally converted into H3O + .

[0110] Example 2

[0111] The process and conditions are the same as in Example 1, except that:

[0112] The voltage difference U applied to the light introduction electrode 7 and the outlet electrode 13 (i.e., the reaction zone 9) is controlled to be fixed at 2.3V; the injection volume q of the sample gas 1 at atmospheric pressure is controlled to be 5-500mL / min by adjusting the valve 3, and the movement speed v of the ions in the gas flow field is changed. g , regulating the ion-molecule reaction time in the reaction zone 9, thereby regulating the progress of the ion-molecule reaction. See Table 2 for details.

[0113] Table 2

[0114]

[0115] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for regulating the reaction process of ions and molecules 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 injection 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); The ionization source cavity (5) is a cylindrical structure with two open ends on the left and right sides. 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), respectively. The left and right side end faces of the annular light introduction electrode (7) are respectively sealed and connected to the right side end face of the insulating ring and the left open end of the ionization source cavity (5). An inlet electrode (6) is provided on the left end surface of the insulating ring; an outlet electrode (13) is provided on the right opening 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 side end surface 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 of the truncated cone-shaped through hole (the bottom surface on the side with a smaller area) faces the direction of 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 radially provided on a side wall surface (e.g., an upper side wall) of the light introduction electrode (7), and an outgoing light beam from a vacuum ultraviolet light source (4) passes through the light inlet and is incident along 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 chamber (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 a side wall surface (e.g., lower side wall) of the ionization source chamber (5) near the exit electrode, and the vacuum pumping port is connected to an external vacuum pump (11) via a valve B (10) for maintaining a vacuum in the ionization source chamber (5); A vacuum gauge (12) for measuring the air pressure in the ionization source cavity (5) is provided at the vacuum exhaust 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 axial 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 q of the sample gas (1) is adjusted by valve A (3) to change the movement speed v of the ions in the gas flow field. g or by adjusting the voltage difference U applied to the light introduction electrode (7) and the outlet electrode (13) (i.e., the reaction zone (9)), changing the movement speed v of the ions in the electric field d ; By changing v g and 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 (type) and intensity (content) 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 course of the ion-molecule reaction or regulating the progress of the ion-molecule reaction.

2. The method according to claim 1, characterized in that: The calculation formula for the time t of the ion-molecule reaction in the reaction zone (9) is: q is the injection volume of sample gas (1) at atmospheric pressure; r is the inner radius of the ionization source cavity (5); p is the gas pressure in the ionization source cavity (5); U is the voltage difference between the light introduction electrode (7) and the exit electrode (13); T is the temperature in the ionization source cavity (5); d is the distance from left to right between the light introduction electrode (7) and the exit electrode (13) (the length of the reaction zone (9) from left to right); K is the ion mobility; K0 is the reduced mobility at a temperature of 273 K and a pressure of 760 Torr.

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 (length from left to right); The inlet electrode (6) and the outlet electrode (13) are parallel plate structures; the middle 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 valve (3) controls the injection volume q of the sample gas (1) at atmospheric pressure to be 5-500 mL / min, and the adjustment range of the injection volume q is 5-300 mL / min; The inner radius r of the ionization source cavity (5) is 0.1-10 cm; the gas pressure p of the ionization source cavity (5) is in the range of 0.1-760 Torr; the temperature T of the ionization source cavity (5) is in the range of 273-500 K; The length d of the reaction zone (9) (along the axis of the ionization source chamber (5)) is 0.5-50 cm.

5. The method according to claim 1, 2 or 4, characterized in that: The voltage difference U applied to the light introduction electrode (7) and the exit electrode (13) is in the range of 0.1-500V, and the step length (i.e., the adjustment amplitude of the voltage difference U) is 0.1-10V; The reduced mobility K0 at 273K and 760Torr can be estimated to be (2.0±0.2)cm 2 V -1 s -1 ; According to the formula in claim 1, it can be calculated that the range of the ion-molecule reaction time t is 1 μs-1s.

6. The method according to claim 1 or 2 or 4 or 5, characterized in that: The sample gas contains a carrier gas, a substance that can be ionized by a vacuum ultraviolet light source (4), and molecules that can react with 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, characterized in that: 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 the 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, characterized in that: The edges around the light outlet of the vacuum ultraviolet light source (4) are tightly connected to the outer wall surface 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, characterized in that: The inner diameter of the annular light introduction electrode (7) and the inner diameter of the insulating ring are respectively equal to the inner diameter of the ionization source cavity (5).

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