Ionization device and mass spectrometer

Abstract

The present invention discloses an ionization device, which relates to the technical field of mass spectrometers. It includes a vacuum chamber, in which a light source and an ion transmission region are sequentially arranged from front to back. One end of the ion transmission region close to the light source is connected with a sample gas pipe, and the sample gas pipe can input sample gas into the vacuum chamber. The light source is installed at the front end of the vacuum chamber and can ionize the sample gas. A sleeve is also installed at the front end inside the vacuum chamber. The sleeve is sleeved outside the light source, and the sleeve is connected with a power supply. The power supply can apply a voltage to the sleeve to ionize the sample gas molecules in the sleeve and control the ion movement trajectory in the sleeve. The present invention also provides a mass spectrometer including the above ionization device. The present invention can reduce the mirror surface pollution of the light source, avoid the light intensity loss of the light source, and can control the ion flight trajectory in the sleeve.

Description

Technical Field

[0001] The present invention relates to the technical field of mass spectrometers, and in particular to an ionization device and a mass spectrometer. Background Art

[0002] Natural activities and human activities release a large amount of volatile organic compounds (VOCs) into the atmosphere. The VOCs in the atmosphere are transformed or removed through many physical and chemical processes. In the tropospheric atmosphere, they participate in the formation of ozone and secondary organic aerosols, pose hazards to human health, and damage regional air quality and the global climate. Some VOCs in the atmosphere have a lifespan of only a few seconds or minutes, and some concentrations are at parts per million (ppm) or even parts per trillion (ppt). Their high temporal variability and low concentrations bring higher difficulties to the detection of complex VOCs.

[0003] Mass spectrometers are widely used in the monitoring of trace VOCs in the atmosphere due to their high sensitivity and fast detection speed. The ion source in a mass spectrometer is mainly responsible for ionizing the sample molecules to be detected into ions, which largely determines the detection sensitivity, spectral specificity, analysis accuracy, and the range of analytes of the instrument. Vacuum ultraviolet single photon ionization (VUV-SPI) is a soft ionization technology. When photons irradiate on molecules, the molecules absorb the energy of a single photon and lose an electron to be ionized. Compared with traditional ionization technologies, it has fewer fragment peaks, easier spectral analysis, and higher universality.

[0004] Vacuum ultraviolet VUV lamps are a commonly used ultraviolet light source, with advantages such as small volume, low cost, and easy operation. They are one of the most widely used light sources for commercial single photon ionization mass spectrometry. However, during use, they are adsorbed and contaminated by un-ionized gas molecules, ions after ionization, etc., which affects the output light intensity, resulting in a decrease in the ionization efficiency of the light source, unstable instrument signal intensity, and reduced instrument sensitivity.

[0005] In existing patents, a MgF2 glass sheet is installed at the front end of the vacuum ultraviolet VUV lamp to separate the light source mirror surface from the ionization region. However, this method causes a loss of available light intensity of the light source and requires long-term replacement and cleaning of the glass sheet.

[0006] Therefore, there is an urgent need for a new ionization device and a mass spectrometer to solve the above problems existing in the prior art. Summary of the Invention

[0007] The purpose of the present invention is to provide an ionization device and a mass spectrometer to solve the problems existing in the above prior art, which can reduce the contamination of the light source mirror surface, avoid the loss of light intensity of the light source, and can control the ion flight trajectory in the sleeve.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] The present invention provides an ionization device, including a vacuum chamber. Inside the vacuum chamber, a light source and an ion transport region are sequentially arranged from front to back. One end of the ion transport region close to the light source is connected to a sample gas pipe, and the sample gas pipe can input sample gas into the vacuum chamber. The light source is installed at the front end of the vacuum chamber and can ionize the sample gas. A sleeve is also installed at the front end inside the vacuum chamber. The sleeve is sleeved outside the light source, and the sleeve is connected to a power supply. The power supply can apply a voltage to the sleeve to ionize the sample gas molecules inside the sleeve and control the ion movement trajectory inside the sleeve.

[0010] Preferably, the light source is detachably installed on the front side wall of the vacuum chamber through a flange, and a sealing ring is arranged at the connection between the light source and the vacuum chamber.

[0011] Preferably, the light source adopts a vacuum ultraviolet lamp.

[0012] Preferably, the light source includes a lamp body. The lamp body is installed inside the vacuum chamber. The sleeve is sleeved outside the lamp body, and the length of the sleeve is less than the length of the lamp body.

[0013] Alternatively, the light source includes a lamp body and a lamp nose connected to each other. The lamp body is located outside the vacuum chamber, the lamp nose is installed inside the vacuum chamber, the sleeve is sleeved outside the lamp nose, and the length of the sleeve is less than the length of the lamp nose.

[0014] Preferably, an electric connection pin is welded in the middle of the sleeve, and the electric connection pin is connected to the power supply.

[0015] Preferably, the ion transport region includes an ionization chamber and a transport electrode plate arranged from front to back. Both the ionization chamber and the transport electrode plate are connected to a power supply. An ionization cavity is arranged inside the ionization chamber. Openings are arranged on both the front and rear sides of the ionization cavity. Through holes for ions to pass through are arranged on the transport electrode plate. An air inlet is arranged on the ionization chamber. The air inlet is communicated with the ionization chamber and is connected to the sample gas pipe.

[0016] Preferably, multiple transport electrode plates are arranged from front to back. Adjacent transport electrode plates are separated by insulating gaskets. Through holes for ions to pass through are arranged on the insulating gaskets, and each transport electrode plate is individually applied with a voltage.

[0017] Preferably, an ion lens group is further provided at the rear side of the transmission pole piece. The ion lens group includes an ion lens. The ion lens is installed in the vacuum chamber through a lens base, and a focusing through hole for ions to pass through is provided on the ion lens.

[0018] Preferably, a grid is further provided between the sleeve and the ionization chamber, and a voltage is applied to the grid to block the transmission of ions to the light source.

[0019] Preferably, insulating gaskets are used to insulate between the sleeve, the grid, the ionization chamber, the transmission pole piece, and the ion lens group pairwise.

[0020] The present invention also provides a mass spectrometer, including the above ionization device.

[0021] The present invention has achieved the following technical effects compared with the prior art:

[0022] In the present invention, a sleeve is installed outside the light source to lengthen the distance between the light source and the ionization chamber and expand the ionization space of sample gas molecules. Moreover, the sleeve is connected to a power supply, and an adjustable voltage can be applied to the sleeve to ionize some un-ionized sample gas molecules diffused into the sleeve, reducing the contamination of the light source mirror surface and avoiding the loss of the light intensity of the light source. Furthermore, by adjusting the voltage, the flight trajectory of ions in the sleeve can be controlled, and the ions in the sleeve can be introduced into the ion transmission region, reducing ion loss. The present invention is simple and convenient to operate, and reduces the disassembly and assembly of the ion source part. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic structural diagram of the ionization device of the present invention;

[0025] Figure 2 It is an ion trajectory diagram of the ionization device of the present invention;

[0026] Figure 3 It is a diagram of the signal intensity change of benzene series compounds of the light source sleeve of the present invention under different voltages;

[0027] Wherein: 1 - vacuum ultraviolet lamp, 2 - flange, 3 - O-ring, 4 - sleeve, 5 - grid, 6 - ionization chamber, 7 - first transmission electrode plate, 8 - second transmission electrode plate, 9 - third transmission electrode plate, 10 - fourth transmission electrode plate, 11 - front base, 12 - ion lens, 13 - rear base, 14 - sample gas pipe, 15 - sample gas molecule, 16 - ion, 17 - vacuum chamber. Detailed implementation manners

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] The purpose of the present invention is to provide an ionization device and a mass spectrometer to solve the problems existing in the above-mentioned prior art, which can reduce the mirror surface pollution of the light source, avoid the loss of light intensity of the light source, and can control the ion flight trajectory in the sleeve.

[0030] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0031] As Figures 1 - 3 shown, this embodiment provides an ionization device, which mainly includes a vacuum chamber 17. Inside the vacuum chamber 17, a light source and an ion transmission area are sequentially arranged from front to back. One end of the ion transmission area close to the light source is connected with a sample gas pipe 14, and the sample gas pipe 14 can input sample gas into the vacuum chamber 17; the light source is installed at the front end of the vacuum chamber 17 and can ionize the sample gas molecules 15; a sleeve 4 is also installed at the front end inside the vacuum chamber 17. The sleeve 4 is sleeved outside the light source, and the sleeve 4 is connected with a power supply. The power supply can apply a voltage to the sleeve 4 to ionize the sample gas inside the sleeve 4 and control the movement trajectory of the ions 16 inside the sleeve 4. Among them, the sleeve 4 is made of a conductive material. In this embodiment, a metal material is used. The power supply is an adjustable power supply, which can apply an adjustable DC voltage to the sleeve 4 to ionize the un-ionized sample gas molecules 15 diffused into the inside of the sleeve 4, and by adjusting the voltage, the flight trajectory of the ions 16 inside the sleeve 4 can be controlled; specifically, by increasing the voltage, the ions 16 can move towards the ion transmission area.

[0032] In this embodiment, the end of the vacuum chamber 17 where the light source is installed is the front end, that is, the left end facing the paper surface is the front end, and the right end is the rear end; an opening is also provided at the rear end of the vacuum chamber, which can be connected to subsequent instruments for easy detection; alternatively, the detection instrument can be directly placed inside the vacuum chamber 17 for detection.

[0033] In this embodiment, the light source is detachably installed on the front side wall of the vacuum chamber 17 through a flange 2, and a sealing ring is provided at the connection between the light source and the vacuum chamber 17 for sealing; among them, the sealing ring preferably adopts an O-ring 3.

[0034] In this embodiment, the light source preferably adopts a vacuum ultraviolet lamp (VUV lamp), or other light sources can be selected according to specific working needs.

[0035] In this embodiment, the light source includes a lamp body, the lamp body is installed inside the vacuum chamber 17, a sleeve 4 is sleeved outside the lamp body, and the length of the sleeve 4 is less than the length of the lamp body;

[0036] Alternatively, in this embodiment, the light source preferably includes a lamp body and a lamp nose connected to each other. The lamp body is located outside the vacuum chamber 17, and the lamp nose is installed inside the vacuum chamber 17 and connected to the vacuum chamber 17 through an O-ring 3, so that the lamp nose is in a vacuum environment; the sleeve 4 is sleeved outside the lamp nose, and the length of the sleeve 4 is less than the length of the lamp body. In this embodiment, by moving the position of the lamp nose and the O-ring 3, the distance from the mirror surface of the light source to the ionization chamber 6 can be changed, and the ionization space of the sample can be expanded; specifically, by adjusting the connection position of the flange 2 on the lamp nose, the position of the lamp nose and the O-ring 3 can be adjusted, that is, the position of the lamp nose inside the vacuum chamber 17 can be adjusted.

[0037] In this embodiment, the sleeve 4 is in the shape of a long cylinder, and the length and inner diameter of the sleeve 4 are selected according to specific working needs; among them, the inner diameter of the sleeve 4 is preferably 10 mm to 50 mm, slightly larger than the diameter of the lamp nose or the lamp body, and the length of the sleeve 4 is preferably 20 to 70 mm, slightly larger than the length of the lamp nose or the lamp body, to ensure that there is an ionization space inside the sleeve 4 and prevent the lamp body or the lamp nose from protruding from the sleeve 4 and being contaminated; when part of the lamp body or the lamp nose is inside the vacuum chamber 17 and part is outside, the sleeve length can be slightly shorter than the length of the lamp nose or the lamp body, as long as there is an ionization space inside the sleeve 4.

[0038] In this embodiment, an electric connection needle is also welded in the middle of the sleeve 4, and the electric connection needle is connected to the power supply, and an adjustable DC voltage can be applied to the sleeve 4 through the electric connection needle.

[0039] In this embodiment, the ion transport region includes an ionization chamber 6 and a transport electrode plate arranged from front to back; an ionization cavity is arranged in the ionization chamber 6, which can provide space for the ionization of sample gas molecules 15. An air inlet is arranged on the ionization chamber 6, and the air inlet is communicated with the ionization chamber 6 and connected to the sample gas pipe 14, so that the sample gas can enter the ionization cavity; wherein, the sample gas pipe 14 is a capillary. Further, openings are arranged in the middle of the front and rear sides of the ionization cavity, and the light emitted by the light source can pass through the sleeve 4 and enter from the front side opening of the ionization cavity to ionize the sample gas molecules 15 in the ionization cavity. The ions 16 generated by ionization can enter the transport electrode plate from the rear side opening, and a through hole for the ions 16 to pass through is correspondingly arranged in the middle of the transport electrode plate.

[0040] In this embodiment, multiple transport electrode plates are arranged from front to back, and adjacent transport electrode plates are insulated from each other by insulating gaskets. Through holes for the ions 16 to pass through are correspondingly arranged on the insulating gaskets, and a DC voltage is applied to each transport electrode plate separately to enable the transport of the ions 16; wherein, preferably four transport electrode plates are arranged. The transport electrode plates are electrode plates with through holes in the middle, and the diameter of the through hole on the frontmost transport electrode plate is smaller than that of the through holes on the rear transport electrode plates.

[0041] In this embodiment, an ion lens group is further arranged at the rear side of the transport electrode plate. The ion lens group includes an ion lens 12, and the ion lens 12 is installed in the vacuum chamber 17 through a lens base. A focusing through hole for the ions 16 to pass through is arranged on the ion lens 12. Among them, the ion lens 12 includes two semi-circular electrode plates arranged up and down. A focusing through hole is formed between the connection parts of the two semi-circular electrode plates. The semi-circular electrode plates are connected to a power supply to apply a voltage. By applying a voltage to the two semi-circular electrode plates, the ions 16 can be moved towards the middle for focusing and then pass through the focusing through hole.

[0042] In this embodiment, the lens base includes a front base 11 and a rear base 13. The front base 11 and the rear base 13 are respectively arranged on the front side and the rear side of the ion lens 12, and the front base 11 and the rear base 13 are used to fix the ion lens 12 in the vacuum chamber 17; wherein, the front base 11 and the rear base 13 are circular metal bases and are grounded. The ion lens 12 is separated from the front base 11 and the rear base 13 by insulating gaskets; and a through hole for the ions 16 to pass through is also correspondingly arranged in the middle of the lens base.

[0043] In this embodiment, a metal grid 5 is further arranged between the sleeve 4 and the ionization chamber 6. A DC voltage is applied to the grid 5 to block the transmission of the ions 16 towards the light source.

[0044] In this embodiment, the light source, the sleeve 4, the opening of the ionization chamber 6, the through holes on the transfer electrode plate, and the focusing through holes on the ion lens 12 are coaxially arranged to facilitate the passage of light and ions 16; and insulating gaskets are used to insulate between the sleeve 4, the grid 5, the ionization chamber 6, the transfer electrode plate, and the ion lens group pairwise.

[0045] The present invention also provides a mass spectrometer, including the above ionization device.

[0046] As Figure 2 shown, in this embodiment, according to the specific structure of the ionization device, the model size in Simion is abstracted. The simulation object is 50 positively charged ions 16 with a charge of +1 valence and a mass-to-charge ratio of 78. It is simulated that the sample gas molecules 15 diffuse to the sleeve 4 and are ionized into ions 16. When a voltage higher than that of the ionization chamber 6 is applied to the sleeve 4, the ions 16 fly towards the ion transmission area from the sleeve 4.

[0047] As Figure 3 shown, it is found that when the voltage of the sleeve 4 is greater than or equal to the voltage (20 V) of the ionization chamber 6, the signal intensity of the ions 16 is significantly higher than the case where the sleeve 4 is grounded, indicating that some ions 16 reach the inside of the sleeve 4 or the sample gas molecules 15 are ionized in the lamp sleeve 4 and are introduced into the ion transmission area.

[0048] In this specification, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, based on the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An ionization device, characterized in that: It includes a vacuum chamber, in which a light source and an ion transmission area are arranged in sequence from front to back. A sample gas pipe is connected to one end of the ion transmission area close to the light source, and the sample gas pipe can input sample gas into the vacuum chamber. The light source is installed at the front end of the vacuum chamber and can ionize the sample gas. A sleeve is also installed at the front end of the vacuum chamber. The sleeve is sleeved outside the light source, and the light source does not protrude from the sleeve. An ionization space is provided inside the sleeve. And the sleeve is connected to a power supply, and the power supply can apply a voltage to the sleeve to ionize the sample gas molecules inside the sleeve and control the ion movement trajectory inside the sleeve. By increasing the voltage, the ions can be made to move towards the ion transmission area. The light source is detachably installed on the front side wall of the vacuum chamber through a flange, and a sealing ring is provided at the connection between the light source and the vacuum chamber. The sealing ring adopts an O-ring. The light source includes a lamp body and a lamp nose connected to each other. The lamp body is located outside the vacuum chamber, and the lamp nose is installed inside the vacuum chamber and connected to the vacuum chamber through the O-ring. The sleeve is sleeved outside the lamp nose. By adjusting the connection position of the flange on the lamp nose, the position of the lamp nose and the O-ring can be adjusted, so as to change the distance from the mirror surface of the light source to the ionization chamber of the ion transmission area and expand the ionization space of the sample gas.

2. The ionization device according to claim 1, characterized in that: The light source adopts a vacuum ultraviolet lamp.

3. The ionization device according to claim 1, characterized in that: A power connection pin is welded in the middle of the sleeve, and the power connection pin is connected to the power supply.

4. The ionization device according to claim 1, characterized in that: The ion transmission area includes an ionization chamber and a transmission pole piece arranged from front to back. Both the ionization chamber and the transmission pole piece are connected to the power supply. An ionization cavity is provided inside the ionization chamber, and openings are provided on both the front and back sides of the ionization cavity. Through holes for ions to pass through are provided on the transmission pole piece. An air inlet is provided on the ionization chamber, and the air inlet is communicated with the ionization chamber and is connected to the sample gas pipe.

5. The ionization device according to claim 4, characterized in that: A plurality of transmission pole pieces are arranged from front to back, and adjacent transmission pole pieces are separated by insulating gaskets. Through holes for ions to pass through are provided on the insulating gaskets, and each transmission pole piece is individually applied with a voltage.

6. The ionization device according to claim 4 or 5, characterized in that: An ion lens group is further provided at the rear side of the transmission pole piece. The ion lens group includes an ion lens. The ion lens is installed inside the vacuum chamber through a lens base, and a focusing through hole for ions to pass through is provided on the ion lens.

7. The ionization device according to claim 6, characterized in that: A grid is further provided between the sleeve and the ionization chamber, and a voltage is applied to the grid to block the ions from transmitting towards the light source.

8. The ionization device according to claim 7, wherein: Insulating gaskets are used for insulation between the sleeve, the grid, the ionization chamber, the transmission pole piece and the ion lens group in pairs.

9. A mass spectrometer, characterized in that: It includes an ionization device according to any one of claims 1-8.

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