CN117524840A - Spatially focused VUV photoinitiated ionization source - Google Patents
Spatially focused VUV photoinitiated ionization source Download PDFInfo
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- CN117524840A CN117524840A CN202210896713.5A CN202210896713A CN117524840A CN 117524840 A CN117524840 A CN 117524840A CN 202210896713 A CN202210896713 A CN 202210896713A CN 117524840 A CN117524840 A CN 117524840A
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- 150000002500 ions Chemical class 0.000 claims abstract description 43
- 238000001871 ion mobility spectroscopy Methods 0.000 claims description 22
- 230000003287 optical effect Effects 0.000 claims description 18
- 238000007789 sealing Methods 0.000 claims description 16
- 239000007789 gas Substances 0.000 claims description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000004949 mass spectrometry Methods 0.000 claims description 6
- 230000035945 sensitivity Effects 0.000 claims description 6
- 238000009413 insulation Methods 0.000 claims description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 238000000451 chemical ionisation Methods 0.000 claims description 4
- 229910052743 krypton Inorganic materials 0.000 claims description 3
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 claims description 3
- 230000002093 peripheral effect Effects 0.000 claims description 3
- 229910052786 argon Inorganic materials 0.000 claims description 2
- 239000001307 helium Substances 0.000 claims description 2
- 229910052734 helium Inorganic materials 0.000 claims description 2
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 229910052724 xenon Inorganic materials 0.000 claims description 2
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 2
- 238000004458 analytical method Methods 0.000 abstract description 2
- 230000005540 biological transmission Effects 0.000 abstract description 2
- 230000003247 decreasing effect Effects 0.000 abstract 2
- 230000002238 attenuated effect Effects 0.000 abstract 1
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- 238000005215 recombination Methods 0.000 abstract 1
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- 238000006243 chemical reaction Methods 0.000 description 5
- 239000003153 chemical reaction reagent Substances 0.000 description 5
- 238000001514 detection method Methods 0.000 description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 4
- 230000002285 radioactive effect Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
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- 238000010586 diagram Methods 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 230000005012 migration Effects 0.000 description 2
- 238000013508 migration Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 150000001793 charged compounds Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
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- 229940079593 drug Drugs 0.000 description 1
- 238000000132 electrospray ionisation Methods 0.000 description 1
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- 238000009434 installation Methods 0.000 description 1
- 230000005596 ionic collisions Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000941 radioactive substance Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
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- 238000000926 separation method Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 231100000167 toxic agent Toxicity 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/10—Ion sources; Ion guns
- H01J49/16—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission
- H01J49/161—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission using photoionisation, e.g. by laser
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/622—Ion mobility spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
- G01N27/64—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/10—Ion sources; Ion guns
- H01J49/14—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers
- H01J49/145—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers using chemical ionisation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/10—Ion sources; Ion guns
- H01J49/16—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission
- H01J49/161—Ion sources; Ion guns using surface ionisation, e.g. field-, thermionic- or photo-emission using photoionisation, e.g. by laser
- H01J49/162—Direct photo-ionisation, e.g. single photon or multi-photon ionisation
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Abstract
The invention relates to an ionization source in an analysis instrument, in particular to a spatially focused VUV photoinitiated ionization source, which comprises a VUV lamp, wherein at least two pairs of discharge electrodes are arranged outside the VUV lamp, and all electrodes are uniformly distributed on the outer surface of the VUV lamp; the same voltage is applied to the electrode pairs facing each other, and different voltages are applied to the adjacent electrodes; the advantages that a radio frequency trap is formed, ions generated by discharge cannot bombard the inner surface of the lamp to peel off and pollute the lamp, and signals are attenuated; designing a plurality of similar transmission electrode pairs at different positions in the axial direction of the rear of the radio frequency lamp, applying radio frequency voltage and superposing direct current voltage; the potential across the electrode pairs is gradually increased or decreased at different positions, gradually decreased in the positive ion mode and gradually increased in the negative ion mode. Its advantages are no recombination of product ions on surface, and high signal strength.
Description
Technical Field
The invention relates to an ionization source in an analysis instrument, in particular to a spatially focused VUV photoinitiation ionization source, which is characterized in that a radio frequency field is utilized to realize radial focusing of ions to avoid diffusion loss of the ions on the wall, and an axial driving of the ions is realized through a superimposed direct current electric field.
Background
Mass spectrometry and ion mobility spectrometry are two typical ion-type detection instruments, and the separation principle is that various compounds are characterized by mass spectra or mobility of gaseous ions respectively. The method is widely applied to detection of volatile organic pollutants in chemical toxic agents, drugs, dangerous goods and atmospheric environment.
Ionization sources are one of the key technologies for analytical instruments such as ion mobility spectrometry. The ionization source commonly used in conventional ion mobility spectrometry is radioactivity 63 Ni ionization source. 63 Ni can emit beta rays with average energy of 17Kev, and the beta rays and carrier gas undergo a series of complex reactions to finally form reagent ions H 3 O + (positive ion detection mode) and O 2 _ (negative ion detection mode), the reagent ions react with the sample to be detected again, so that the sample to be detected is ionized. Radioactivity (radioactivity) 63 Ni ionization sources are favored by scientists because of their simplicity, stability, no need for external power supply, etc., but are cumbersome to practical use due to their safety checks and special safety measures due to their radioactivity. In addition 63 The ion concentration generated by the Ni ionization source is not high enough, so that the traditional ion mobility spectrometry signal is weak, and the linear range is small. In recent years, non-radioactive ionization sources have therefore been actively sought in an effort to replace conventional radioactivity 63 Ni ionization source. Several non-radioactive ionization sources for ion mobility spectrometry are photoionization sources (including VUV lamps and lasers), corona discharge ionization sources, and electrospray ionization sources specifically for ionizing liquids, among others.
Li Haiyang et al, a radio frequency focusing enhanced vacuum ultraviolet mass spectrometry ionization source (patent number CN201711273062. X). The ultraviolet ionization source based on the radio frequency segmented quadrupole focusing enhancement for mass spectrometry comprises an ionization source cavity, a vacuum ultraviolet lamp, a repulsion electrode, a gas sampling tube, segmented quadrupole rods and a differential electrode. The ionization source utilizes the quadrupole rods to improve the ion collision frequency under the medium air pressure, enhances the performances of focusing and the like, improves the ion transmission efficiency and the probability of molecular ion reaction, realizes the enhancement of the ionization efficiency of the vacuum ultraviolet ionization source, and can greatly improve the instrument sensitivity. Meanwhile, the structure of the introduced segments can control the proper axial electric field, control the reaction rate and the dissociation energy to improve the selectivity of the ionization source. The method has the defects that the design and processing cost of the radio frequency segmented four-stage rod is relatively high, and the installation and the debugging are difficult.
Disclosure of Invention
The invention aims to solve the technical problems of overcoming the defects in the prior art, and providing the VUV photoinitiated ionization source capable of providing high-efficiency space focusing for stabilizing reagent ions, so that the surface of a cavity body is prevented from being sputtered and polluted by the ions in a radio frequency lamp, and the stability is improved. The ionization source is used for mass spectrum and ion mobility spectrometry, so that the use of a radioactive ionization source can be avoided, and the sensitivity of the ion mobility spectrometry is improved; meanwhile, a single sample ion peak is formed, so that high-selectivity detection is realized, and the industrialization of ion mobility spectrometry is facilitated.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a spatially focused VUV photoinitiated ionization source comprises a hollow cylindrical insulating discharge cavity and a hollow cylindrical ionization hollow cavity with left and right ends open;
the discharge cavity is a hollow closed cavity, and the cavity is filled with gas; a circular through hole serving as an optical window is formed in the right side wall surface of the insulating discharge cavity, an optical window sheet which transmits ultraviolet light is arranged at the window, and the window is sealed through the optical window sheet; the right side of the discharge cavity window is connected with the left opening end of the ionization hollow cavity in a sealing way, and the insulation discharge cavity, the window and the ionization hollow cavity are coaxially arranged; a gas inlet is arranged on the side wall of one side of the ionization hollow cavity, which is close to the optical window; the outer side wall surface of the discharge cavity is provided with 1 group or more than 2 groups of discharge electrode groups which are formed by 2N pairs of arc-shaped strip-shaped discharge electrodes (N is a positive integer) arranged along the same circumference along the axial direction, wherein the arc-shaped strip-shaped discharge electrodes refer to the fact that the cross sections of the inner surfaces of the electrodes perpendicular to the axial direction of the discharge cavity are arc lines, the shapes of the discharge electrodes are the same and the sizes of the discharge electrodes are equal, the arc lines of the cross sections of the inner surfaces of the electrodes in the discharge electrode groups are positioned on the circumference of the same circle with the circle center positioned on the axial line of the discharge cavity and are uniformly distributed at equal intervals on the circumference, the electrodes are arranged on the outer side wall surface of the discharge cavity, two electrodes in each pair of the discharge electrodes are oppositely arranged one by taking the axial line of the discharge cavity as a symmetrical axis, and the upper voltages and the phases of the electrode pairs in each group of the electrodes which are symmetrical by the axial line are the same; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated;
the outer side wall surface of the ionization hollow cavity is provided with 1 group or more than 2 groups of mutually-spaced focusing electrode groups formed by 2N pairs (N is a positive integer) of arc-shaped strip-shaped discharge electrodes arranged along the same circumference along the axial direction, wherein the arc-shaped strip-shaped discharge electrodes are arc lines on the inner surface of each electrode, the sections of the arc-shaped strip-shaped discharge electrodes are perpendicular to the axial direction of the ionization hollow cavity, the shapes of the discharge electrodes are identical in size, the arc lines on the sections of the inner surface of each electrode are positioned on the circumference of the same circle with the circle center positioned on the axis of the ionization hollow cavity, the arc lines are uniformly distributed on the circumference at equal intervals, the electrodes are arranged on the outer side wall surface of the ionization hollow cavity, and two electrodes in each pair of discharge electrodes are oppositely arranged one by taking the axis of the ionization hollow cavity as a symmetrical axis; 2 or more than 2 focusing electrode groups are arranged on the outer side wall surface of the ionization hollow cavity along the axial direction; the voltages on the electrodes which are symmetrical with the axis in each group of electrodes are equal, and the phases are the same; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated; the opening end of one side of the ionization hollow cavity far away from the cylindrical insulation discharge cavity is an ion outlet.
Alternating voltage is applied to the electrode group on the outer side wall surface of the ionization hollow cavity, wherein the amplitude of the alternating voltage is 500-3000V high voltage, and the frequency is 50-1000 MHz.
Alternating voltage is applied to electrode groups on the outer side wall surface of the cylindrical insulating discharge cavity, wherein the voltages on the electrodes which are symmetrical in axis in each group are equal, and the phases are the same; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated; the amplitude of the applied alternating voltage is high voltage of 200V-2000V, and the frequency is 100kHz to 1000MHz.
The ionization source gas is one or more of nitrogen, helium, argon, krypton, xenon and air.
The optical window sheet is a quartz glass sheet, and the peripheral edges of the quartz glass sheet are hermetically connected with the inner wall surface of the through hole of the window;
a sealing ring is arranged between the discharge cavity and the ionization hollow cavity, and sealing between the discharge cavity and the ionization hollow cavity is realized through the sealing ring.
Respectively superposing direct current voltage D on electrode pairs in each group of electrodes of the insulating discharge cavity and the ionization hollow cavity, wherein the voltage D superposed on the cylindrical insulating discharge cavity and the ionization hollow cavity is related to the polarity of ions to be detected; the voltage D superposed on each electrode group from left to right along the axis direction, and the superposed direct current voltage D is sequentially reduced when positive ions are detected; when negative ions are detected, the superimposed direct current voltage D is sequentially reduced and increased.
It can realize the switch between single photon ionization and chemical ionization: in a single photon ionization mode, a sample with lower energy than photons enters an ionization hollow cavity through a sample inlet for direct ionization; and the sample to be detected and the sample with higher photon energy enter the ionization hollow cavity through the sample inlet at the same time in the chemical ionization mode.
The ionization source is combined with a mass spectrum or an ion mobility spectrometry to improve the sensitivity of the mass spectrum or the ion mobility spectrometry.
The invention has the advantages that: the spatially focused VUV photoinitiated ionization source is used for mass spectrum and ion mobility spectrometry plasma detectors to replace the traditional radioactive source, so that radioactive substances can be avoided, the sensitivity and identification accuracy of the ion mobility spectrometry can be improved, the attenuation of light intensity can be avoided, the stability can be improved, and the industrialization of the ion mobility spectrometry can be facilitated.
The spatial ionization source of the present invention has particular advantages over other ionization sources. Inside the radio frequency field VUV lamp; in addition, the influence of the composition change of the ambient gas on the ionization efficiency is avoided when the ion source is in an open structure, and the ion source is more stable. The ionization source is simple to use, small in structure and beneficial to industrialization of the ion mobility spectrometer.
Drawings
FIG. 1 is a schematic diagram of a spatially focused VUV photoinitiated ionization source;
wherein the components are as follows: the ion discharge device comprises a discharge cavity (1), an ion outlet (2), a discharge electrode group (3), an optical window (4), a wire (5), a sealing ring (6), a sealing ring groove (7), a first focusing electrode pair (8) and a second focusing electrode pair (9); a third focusing electrode pair (10), an ionization hollow cavity (11), a gas inlet (12) and a fourth focusing electrode pair (13);
FIG. 2 is a schematic diagram of a combination of a high efficiency radio frequency VUV photoionization source and an ion mobility spectrometry;
FIG. 3 is a graph of ion mobility spectra of different reagents obtained from a high efficiency radio frequency VUV photoionization source.
Detailed Description
The invention utilizes VUV light generated by dielectric barrier discharge to carry out high-efficiency ionization on a sample, and a specific device is shown in figure 1.
A spatially focused VUV photoinitiated ionization source comprises a hollow cylindrical insulating discharge cavity 1, a hollow cylindrical ionization hollow cavity with left and right ends open;
the discharge cavity is a hollow closed cavity, and the cavity is filled with gas; a circular through hole serving as an optical window 4 is formed in the right side wall surface of the insulating discharge cavity, an optical window sheet which transmits ultraviolet light is arranged at the window, and the window is sealed through the optical window sheet; the right side of the window of the discharge cavity 1 is connected with the left opening end of the ionization hollow cavity 11 in a sealing way, and the insulation discharge cavity 1, the window and the ionization hollow cavity 11 are coaxially arranged; a gas inlet 12 is arranged on the side wall of the ionization hollow cavity 11, which is close to the optical window 4; the outer side wall surface of the discharge cavity 1 is provided with 1 group of discharge electrode groups 3 which are arranged along the same circumference and are formed by 2 pairs of arc-shaped strip-shaped discharge electrodes, wherein the section of the inner surface of each arc-shaped strip-shaped discharge electrode is an arc line perpendicular to the axial direction of the discharge cavity, the shapes of the discharge electrodes are the same, the sizes of the arc lines of the inner surfaces of the electrodes in the discharge electrode groups 3 are equal, the arc lines of the inner surfaces of the electrodes are positioned on the circumference of the same circle with the circle center on the axis of the discharge cavity, the arc lines are uniformly distributed on the circumference at equal intervals, the electrodes are arranged on the outer side wall surface of the discharge cavity, two electrodes in each pair of discharge electrodes are oppositely arranged one by taking the axis of the discharge cavity as a symmetry axis, and the voltages on the electrode pairs with the axis symmetry are the same, and the phases are the same; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated;
the outer side wall surface of the ionization hollow cavity 11 is provided with 2 groups of mutually-spaced focusing electrode groups which are respectively formed by 2 pairs of arc-shaped strip-shaped discharge electrodes arranged along the same circumference along the axial direction; the arc-shaped strip-shaped discharge electrodes are characterized in that the cross section of the inner surfaces of the electrodes perpendicular to the axial direction of the ionization hollow cavity is an arc line, the shapes of the discharge electrodes are identical in size, the arc lines of the inner surfaces of the electrodes are positioned on the circumference of the same circle with the circle center positioned on the axis of the ionization hollow cavity, the arc lines are uniformly distributed at equal intervals on the circumference, the electrodes are arranged on the outer side wall surface of the ionization hollow cavity, and two electrodes in each pair of discharge electrodes are oppositely arranged one by taking the axis of the ionization hollow cavity as a symmetry axis; 2 pairs of focusing electrode groups are arranged on the outer side wall surface of the ionization hollow cavity 11 along the axial direction; the voltages on a pair of electrodes which are symmetrical by the axis are equal and the phases are the same; the voltages applied to the other pair of electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated; the opening end of one side of the ionization hollow cavity 11 far away from the cylindrical insulation discharge cavity 1 is an ion outlet 2.
An alternating voltage is applied to the electrode group on the outer side wall surface of the ionization hollow cavity 11, wherein the amplitude of the voltage is 500V high voltage, and the frequency is 2MHz.
Applying alternating voltage to electrode groups on the outer side wall surface of the cylindrical insulating discharge cavity 1, wherein the voltages on the electrodes which are symmetrical with each other by the axis in each group are equal, and the phases are the same; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated; the amplitude of the applied alternating voltage is 500V high voltage with a frequency of 1MHz.
The ionization source gas is krypton.
The optical window sheet is a quartz glass sheet, and the peripheral edges of the quartz glass sheet are hermetically connected with the inner wall surface of the through hole of the window;
a sealing ring 6 is arranged between the discharge cavity 1 and the ionization hollow cavity 11, and the sealing between the discharge cavity 1 and the ionization hollow cavity 11 is realized through the sealing ring 6.
Respectively superposing direct current voltages D on electrode pairs of the insulating discharge cavity 1 and the ionization hollow cavity 11, and sequentially reducing the superposed direct current voltages D when positive ions are detected; when negative ions are detected, the superimposed direct current voltage D is sequentially reduced and increased.
Single photon ionization can be realized, and a sample with lower energy than photon energy enters the ionization hollow cavity 11 through the sample inlet 12 for direct ionization.
The ionization source is combined with a mass spectrum or an ion mobility spectrometry to improve the sensitivity of the mass spectrum or the ion mobility spectrometry.
The ionization source described above was used in combination with an ion mobility spectrometry as an ionization source of the ion mobility spectrometry, and the structure thereof is shown in fig. 2. The instrument mainly comprises the following parts: the ion discharge device comprises a discharge cavity 1, an ion outlet 2, a discharge electrode group 3, an optical window 4, a lead 5, a sealing ring 6, a sealing ring groove 7, a first focusing electrode pair 8 and a second focusing electrode pair 9; a third focusing electrode pair 10, an ionization hollow chamber 11, a gas inlet 12, a fourth focusing electrode pair 13, a reaction zone 14, an ion gate 15, a migration zone 16, a shielding grid 17, and an ion detector 18. The process of detecting the sample is as follows: acetone enters the ionization hollow cavity 11 through the gas inlet 12, and reactant ions are obtained under the action of vacuum ultraviolet light generated by the discharge cavity 1; the reagent ions are in the first focusing electrode pair 9; the second focusing electrode pair 10, the gas inlet 12 and the third focusing electrode pair 13 enter the reaction zone 14 under the action of the first focusing electrode pair; then enters the migration zone (16) through the ion gate (15); finally, the ion passes through the shielding grid 17 and is detected by the ion detector 18.
FIG. 3 shows a spectrum of acetone determination using the present ionization source in combination with ion mobility spectrometry.
Claims (8)
1. A spatially focused VUV photoinitiated ionization source characterized by: comprises a hollow cylindrical insulating discharge cavity (1) and a hollow cylindrical ionization hollow cavity (11) with left and right ends open;
the discharge cavity is a hollow closed cavity, and the cavity is filled with gas; the right side wall surface of the insulating discharge cavity is provided with a circular through hole serving as an optical window (4), an optical window sheet which transmits ultraviolet light is arranged at the window, and the window is sealed through the optical window sheet; the right side of the window of the discharge cavity (1) is connected with the left opening end of the ionization hollow cavity (11) in a sealing way, and the insulation discharge cavity (1), the optical window (4) and the ionization hollow cavity (11) are coaxially arranged; a gas inlet (12) is arranged on the side wall of the ionization hollow cavity (11) close to the optical window (4); the outer side wall surface of the discharge cavity (1) is provided with 1 group or more than 2 groups of discharge electrode groups (3) which are formed by 2N pairs (N is a positive integer) of arc-shaped strip-shaped discharge electrodes arranged along the same circumference along the axial direction, wherein the arc-shaped strip-shaped discharge electrodes are the inner surfaces of the electrodes, the cross sections perpendicular to the axial direction of the discharge cavity are arc lines, the shapes of the discharge electrodes are the same and the sizes are the same, the arc lines of the cross sections of the inner surfaces of the electrodes in the discharge electrode groups (3) are positioned on the circumference of the same circle with the circle center on the axis of the discharge cavity, the arc lines are uniformly distributed at equal intervals on the circumference, the electrodes are arranged on the outer side wall surface of the discharge cavity, the two electrodes in each pair of the discharge electrodes are arranged in a one-to-one opposite mode by taking the axis of the discharge cavity as a symmetrical axis, and the electrode pairs in each group of the electrodes which are symmetrical along the axis are the same in voltage and the phase; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated;
the outer side wall surface of the ionization hollow cavity (11) is provided with 1 group or more than 2 groups of mutually-spaced focusing electrode groups formed by 2N pairs (N is a positive integer) of arc-shaped strip-shaped discharge electrodes arranged along the same circumference along the axial direction, wherein the arc-shaped discharge electrodes refer to the inner surfaces of the electrodes, the cross sections perpendicular to the axial direction of the ionization hollow cavity are arc lines, the shapes of the discharge electrodes are the same and the sizes are equal, the arc lines of the cross sections of the inner surfaces of the electrodes are positioned on the circumference of the same circle with the circle center positioned on the axis of the ionization hollow cavity, the intervals on the circumference are equal and uniform, the electrodes are arranged on the outer side wall surface of the ionization hollow cavity, and two electrodes in each pair of discharge electrodes are oppositely arranged one by taking the axis of the ionization hollow cavity as a symmetry axis; the voltages on the electrodes which are symmetrical with the axis in each group of electrodes are equal, and the phases are the same; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated;
an opening end at one side of the ionization hollow cavity (11) far away from the cylindrical insulating discharge cavity (1) is an ion outlet (2).
2. The ionization source of claim 1, wherein: an alternating voltage is applied to the electrode group on the outer side wall surface of the ionization hollow cavity (11), wherein the amplitude of the voltage is 500-3000V high voltage, and the frequency is 50Hz to 1000MHz.
3. The ionization source of claim 1, wherein: alternating voltage is applied to electrode groups on the outer side wall surface of the cylindrical insulating discharge cavity (1), wherein the voltages on the electrodes which are symmetrical with each other with the axis in each group are equal, and the phases are the same; the applied voltages on the adjacent electrodes are equal, and the alternating voltages with 180 degrees of phase difference are generated; the amplitude of the applied alternating voltage is high voltage of 200V-2000V, and the frequency is 100kHz to 1000MHz.
4. The ionization source of claim 1, wherein: the gas is one or more of nitrogen, helium, argon, krypton, xenon and air.
5. The ionization source of claim 1, wherein: the optical window sheet is a quartz glass sheet, and the peripheral edges of the quartz glass sheet are hermetically connected with the inner wall surface of the through hole of the window;
a sealing ring (6) is arranged between the discharge cavity (1) and the ionization hollow cavity (11), and the sealing between the discharge cavity (1) and the ionization hollow cavity (11) is realized through the sealing ring (6).
6. The ionization source of claim 1, wherein: the direct current voltage D is respectively superposed on electrode pairs in each group of electrodes of the insulating discharge cavity (1) and the ionization hollow cavity (11), and the voltage D superposed on the cylindrical insulating discharge cavity (1) and the ionization hollow cavity (11) is related to the polarity of ions to be detected; the voltage D superposed on each electrode group from left to right along the axis direction, and the superposed direct current voltage D is sequentially reduced when positive ions are detected; when negative ions are detected, the superimposed direct current voltage D is sequentially reduced and increased.
7. The ionization source of claim 1, wherein: it can realize the switch between single photon ionization and chemical ionization: in a single photon ionization mode, a sample with lower energy than photons enters an ionization hollow cavity (11) through a sample inlet (12) for direct ionization; the sample to be detected and the sample with higher photon energy enter the ionization hollow cavity (11) through the sample inlet (12) at the same time in the chemical ionization mode.
8. Use of an ionization source according to any one of claims 1 to 7 in mass spectrometry or ion mobility spectrometry, in combination with mass spectrometry or ion mobility spectrometry, to increase the sensitivity of the mass spectrometry or ion mobility spectrometry.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210896713.5A CN117524840A (en) | 2022-07-28 | 2022-07-28 | Spatially focused VUV photoinitiated ionization source |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210896713.5A CN117524840A (en) | 2022-07-28 | 2022-07-28 | Spatially focused VUV photoinitiated ionization source |
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| Publication Number | Publication Date |
|---|---|
| CN117524840A true CN117524840A (en) | 2024-02-06 |
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| CN202210896713.5A Pending CN117524840A (en) | 2022-07-28 | 2022-07-28 | Spatially focused VUV photoinitiated ionization source |
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