CN116246933A - High-efficiency space focusing VUV ionization source - Google Patents

High-efficiency space focusing VUV ionization source Download PDF

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Publication number
CN116246933A
CN116246933A CN202111493713.2A CN202111493713A CN116246933A CN 116246933 A CN116246933 A CN 116246933A CN 202111493713 A CN202111493713 A CN 202111493713A CN 116246933 A CN116246933 A CN 116246933A
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ion
electrode
cylindrical
cavity
cylindrical cavity
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CN202111493713.2A
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王卫国
黄卫
李杭
仓怀文
李海洋
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Dalian Institute of Chemical Physics of CAS
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Dalian Institute of Chemical Physics of CAS
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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
    • H01J49/06—Electron- or ion-optical arrangements
    • H01J49/062—Ion guides
    • H01J49/063—Multipole ion guides, e.g. quadrupoles, hexapoles
    • 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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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Abstract

The invention relates to an ionization source in an analysis instrument, in particular to a high-efficiency space focusing VUV ionization source, which comprises a hollow closed cylindrical cavity, wherein two ends of the closed cylindrical cavity are respectively provided with a VUV lamp, a convex lens and an ion outlet; the VUV lamp, the convex lens, the cylindrical cavity and the ion outlet are sequentially arranged; a sample inlet is arranged at one side of the closed cylindrical cavity close to the convex lens; an ionization reaction focusing area is arranged in the closed cylindrical cavity; at least one ion transmission area formed by two pairs of cylindrical electrodes is arranged in the closed cylindrical cavity and at one side close to the ion outlet; a tail gas outlet is arranged at one side of the closed cylindrical cavity and at the middle position of the cylindrical electrode; an ion extraction electrode is arranged on one side of the closed cylindrical cavity; the ionization source and mass spectrum or ion mobility spectrometry are combined, so that the focal point size of ions can be reduced, and the ion transmission efficiency and detection sensitivity when passing through sampling micropores are improved.

Description

High-efficiency space focusing VUV ionization source
Technical Field
The invention relates to an ionization source in an analysis instrument, in particular to a high-efficiency VUV photoelectric ionization source technology, which realizes that a sample and VUV light are overlapped in space with high efficiency through special design, improves ionization efficiency, simultaneously applies a radio frequency electric field to carry out space focusing on ions in an ionization reaction area, avoids ion loss caused by radial divergence, and improves ion utilization efficiency; and the convex lens is used for regulating and controlling the spot size of the light beam, and the ion utilization rate in the mass spectrum detection process is improved by combining with ion focusing.
Background
Ionization source is one of the key technologies of mass spectrum and ion mobility spectrometry plasma type detection instruments. 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.
The ionization sources are all surface ionization sources, and the diameter is usually more than 5mm; in order to ensure high vacuum of mass spectrum, sampling is usually carried out by using a sampling hole of a fraction of a millimeter. So that a large amount of product ions generated by ionization are lost. Moreover, a large amount of reactant ions are usually present in the atmospheric pressure ionization source, and can cause saturation of ion trap mass spectrum and quaternary rod mass spectrum storage, so that the number of target ions is limited, and the sensitivity is influenced; in addition, the coulomb repulsion generated by these ions can affect resolution.
Disclosure of Invention
The invention aims to solve the technical problems of overcoming the defects in the prior art, converging large-scale ionization sources under the atmospheric pressure into micro-focus to provide an interface which has ion utilization efficiency and can realize ion screening, thereby improving the sensitivity and resolution of mass spectrum.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a spatially focused VUV ionization source,
the device comprises a hollow closed cylindrical cavity, wherein two ends of the closed cylindrical cavity are respectively provided with a VUV lamp and an ion outlet; the light outlet of the VUV lamp faces the cavity, a convex lens is arranged at the light outlet of the VUV lamp, the emergent light of the VUV lamp is transmitted in the cavity along the axial direction of the cavity after passing through the convex lens, and the VUV lamp, the convex lens, the cylindrical cavity and the ion outlet are sequentially arranged from left to right;
the beam adjusting area formed by the VUV lamp and the convex lens adjusts the diameter of the beam according to the size of the ion outlet;
a sample inlet is arranged at one side of the closed cylindrical cavity close to the convex lens;
at least one quadrupole electrode formed by two pairs of cylindrical electrodes A is arranged in the closed cylindrical cavity and close to the left side of the convex lens, and the axis of the quadrupole electrode is coaxial with the axis of the cavity; as an ionization reaction focusing region;
at least one quadrupole electrode formed by two pairs of cylindrical electrodes B is arranged in the closed cylindrical cavity and at one side close to the ion outlet, and the axis of the quadrupole electrode is coaxial with the axis of the cavity; as an ion transport region;
a tail gas outlet is arranged on the side wall surface of the airtight cylindrical cavity between the cylindrical electrode A and the cylindrical electrode B;
an ion extraction electrode is arranged at the right end of the closed cylindrical cavity.
The ionization source, the cylindrical electrode A and the cylindrical electrode B are close to the inner wall surface of the closed cylindrical cavity, so that the sample is ionized and bound in the ionization reaction focusing area and bound in the ion transmission area; the diameter of the inner cavity of the quadrupole rod electrode surrounded by the cylindrical electrode A is smaller than that of the inner cavity of the quadrupole rod electrode surrounded by the cylindrical electrode B; the amplitude of the radio frequency power supply applied to the cylindrical electrode A is smaller than that applied to the cylindrical electrode B; the RF power frequency applied to the cylindrical electrode A is less than the RF power frequency applied to the cylindrical electrode B.
The ionization source is characterized in that two pairs of cylindrical electrodes of the ionization reaction focusing area are applied with radio frequency voltage and direct current voltage U1 with opposite phases; the two pairs of cylindrical electrodes of the ion transmission area are applied with radio frequency voltage and direct current voltage U2 with opposite phases; the ion extraction electrode is applied with a direct-current voltage U3; during positive ion detection, the potentials of the direct current voltages U1, U2 and U3 gradually decrease; during anion detection, the potentials of the direct current voltages U1, U2 and U3 are gradually increased;
the length of the cylindrical electrode pairs is more than 1 cm, and the number of the electrode pairs is not less than two. A radio frequency power supply for supplying power to the discharge electrode pair, wherein the frequency is 50Hz to 13.6 MHz; the power supply is an isolated power supply, and the isolation withstand voltage is 200 to 5000V. The ionization source is applied to mass spectrum or ion mobility spectrometry, and the ionization source and the mass spectrum or ion mobility spectrometry are combined, so that the focal point size of ions can be reduced, and the ion transmission efficiency and the detection sensitivity when passing through sampling micropores are improved.
The use of the ionization source in mass spectrometry or ion mobility spectrometry.
The application is characterized in that: the ionization source and mass spectrum or ion mobility spectrometry are combined, so that the focal point size of ions can be reduced, and the ion transmission efficiency and detection sensitivity when passing through sampling micropores are improved.
The invention has the advantages that: the invention provides a space focusing VUV ionization source, which is characterized in that a quaternary rod transmission area and an ionization reaction area are mutually impulsive, so that ionization and transmission efficiency are improved; and the secondary space is used for compressing and transmitting to reduce the size of ions, thereby being beneficial to improving the utilization efficiency and sensitivity of the ions.
Drawings
The invention is described in further detail below with reference to the attached drawings and examples:
FIG. 1 is a schematic diagram of the structure of a high efficiency VUV photoionization source. The device comprises a cylindrical cavity (1), a VUV lamp (2), a sample inlet (3), a tail gas outlet (4), a near ion outlet (5), a cylindrical electrode A (6), a cylindrical electrode B (7), a convex lens (8), an ion extraction electrode (11), an ionization reaction focusing region (9) and an ion transmission region (10).
Fig. 2 is a diagram of ionization source and ion trap mass spectrometry.
Figure 3 shows the mass spectrum of VUV photoionization source assay drugs.
Detailed Description
A spatially focused VUV ionization source,
the device comprises a hollow closed cylindrical cavity, wherein two ends of the closed cylindrical cavity are respectively provided with a VUV lamp and an ion outlet; the light outlet of the VUV lamp faces the cavity, a convex lens is arranged at the light outlet of the VUV lamp, the emergent light of the VUV lamp is transmitted in the cavity along the axial direction of the cavity after passing through the convex lens, and the VUV lamp, the convex lens, the cylindrical cavity and the ion outlet are sequentially arranged from left to right; the diameter of the inner part of the cavity is 8mm;
the beam adjusting area formed by the VUV lamp and the convex lens adjusts the diameter of the beam according to the size of the ion outlet; the beam diameter after adjustment is 5mm
A sample inlet is arranged at one side of the closed cylindrical cavity close to the convex lens; the diameter of the inlet is 5mm;
at least one quadrupole electrode formed by two pairs of cylindrical electrodes A is arranged in the closed cylindrical cavity and close to the left side of the convex lens, and the axis of the quadrupole electrode is coaxial with the axis of the cavity; as an ionization reaction focusing region; the diameter of the quadrupole rod is 6mm, and the length is 15mm;
at least one quadrupole electrode formed by two pairs of cylindrical electrodes B is arranged in the closed cylindrical cavity and at one side close to the ion outlet, and the axis of the quadrupole electrode is coaxial with the axis of the cavity; as an ion transport region; the diameter of the quadrupole rod is 8mm, and the length is 10mm;
a tail gas outlet is arranged on the side wall surface of the airtight cylindrical cavity between the cylindrical electrode A and the cylindrical electrode B;
an ion extraction electrode is arranged at the right end of the closed cylindrical cavity;
the ionization source, the cylindrical electrode A and the cylindrical electrode B are close to the inner wall surface of the closed cylindrical cavity, so that the sample is ionized and bound in the ionization reaction focusing area and bound in the ion transmission area; the diameter of the inner cavity of the quadrupole rod electrode surrounded by the cylindrical electrode A is smaller than that of the inner cavity of the quadrupole rod electrode surrounded by the cylindrical electrode B; the amplitude of the radio frequency power supply applied to the cylindrical electrode A is smaller than that applied to the cylindrical electrode B; the RF power frequency applied to the cylindrical electrode A is less than the RF power frequency applied to the cylindrical electrode B. The amplitude of the radio frequency power supply applied to the cylindrical electrode A is 700V; the amplitude of the voltage applied to the cylindrical electrode B is 400V; the frequency of the radio frequency power supply applied to the cylindrical electrode A is 500kHz; the frequency of the radio frequency power supply applied to the cylindrical electrode B is 1.5MHz;
the ionization source is characterized in that two pairs of cylindrical electrodes of the ionization reaction focusing area are applied with radio frequency voltage and direct current voltage U1 with opposite phases; the two pairs of cylindrical electrodes of the ion transmission area are applied with radio frequency voltage and direct current voltage U2 with opposite phases; the ion extraction electrode is applied with a direct-current voltage U3; during positive ion detection, the potentials of the direct current voltages U1, U2 and U3 gradually decrease; during anion detection, the potentials of the direct current voltages U1, U2 and U3 are gradually increased;
the ionization source is applied to mass spectrum or ion mobility spectrometry, and the ionization source and the mass spectrum are combined, so that the focal point size of ions can be reduced, and the ion transmission efficiency and the detection sensitivity when passing through sampling micropores are improved.
The invention utilizes VUV light to ionize the sample with high efficiency. The frequency of the radio frequency power supply is 50Hz, the waveform of the voltage is a sine wave, and the peak value of the voltage is 500V; the voltage of the DC power supply is 500V. The distance between the first annular electrode and the second annular electrode was 2mm, and the distance between the second annular electrode and the third annular electrode was 10mm. The first annular electrode and the radio frequency power supply respectively reduce the starting discharge power supply by introducing a third annular electrode, and the specific device is shown in figure 1. The sample to be tested enters the ionization region on one side of the power supply to ionize under the action of carrier gas, and enters detection equipment such as an ion mobility spectrometry through the ion outlet 10.
The ionization source described above was used in combination with an ion trap mass spectrum as an ionization source for an ion trap mass spectrum, the structure of which is shown in fig. 2. The instrument mainly comprises the following parts: the device comprises a cylindrical cavity 1, a VUV lamp 2, a sample inlet 3, a tail gas outlet 4, an ion outlet 5, a cylindrical electrode A6, a cylindrical electrode B7, a convex lens 8, an ionization reaction focusing region 9, an ion transmission region 10 and an ion extraction electrode 11. The process of detecting the sample is as follows: the sample is ionized under the action of photons emitted by the VUV lamp 2, the sample fully reacts in the ionization reaction focusing region 9, and the sample is efficiently transmitted in the ion transmission region 10; and the ion enters an ion trap mass spectrum 13 through a pulse sample injection interface 12 under the action of an ion extraction electrode 11 for detection.
Figure 3 shows the mass spectrum of VUV photoionization source assay drugs.

Claims (5)

1. A spatially focused VUV ionization source, characterized by:
comprises a hollow closed cylindrical cavity (1), and two ends of the closed cylindrical cavity are respectively provided with a VUV lamp (2) and an ion outlet (5); the light outlet of the VUV lamp (2) faces the inside of the cavity, a convex lens (8) is arranged at the light outlet of the VUV lamp (2), the emergent light of the VUV lamp is transmitted in the axis direction of the cavity after passing through the convex lens, and the VUV lamp (2), the convex lens (8), the cylindrical cavity (1) and the ion outlet (5) are sequentially arranged from left to right;
the beam adjusting area formed by the VUV lamp (2) and the convex lens (8) adjusts the diameter of the beam according to the size of the ion outlet (5);
a sample inlet (3) is arranged at one side of the closed cylindrical cavity (1) close to the convex lens (8);
at least one quadrupole electrode formed by two pairs of cylindrical electrodes A (6) is arranged inside the sealed cylindrical cavity (1) and close to the left side of the convex lens (8), and the axis of the quadrupole electrode is coaxial with the axis of the cavity (1); as an ionization reaction focal zone (9);
at least one quadrupole electrode formed by two pairs of cylindrical electrodes B (7) is arranged in the sealed cylindrical cavity (1) and at one side close to the ion outlet (5), and the axis of the quadrupole electrode is coaxial with the axis of the cavity (1); as an ion transport region (10);
a tail gas outlet (4) is arranged on the side wall surface of the airtight cylindrical cavity (1) between the cylindrical electrode A (6) and the cylindrical electrode B (7);
an ion extraction electrode (11) is arranged at the right end of the closed cylindrical cavity (1).
2. The ionization source of claim 1, wherein:
the cylindrical electrode A (6) and the cylindrical electrode B (7) are arranged close to the inner wall surface of the closed cylindrical cavity (1), so that the sample is ionized and bound in an ionization reaction focusing area (9) and bound in an ion transmission area (10);
the diameter of the inner cavity of the quadrupole rod electrode surrounded by the cylindrical electrode A (6) is smaller than that of the inner cavity of the quadrupole rod electrode surrounded by the cylindrical electrode B (7); the amplitude of the radio frequency power supply applied to the cylindrical electrode A (6) is smaller than that applied to the cylindrical electrode B (7); the RF power frequency applied to the cylindrical electrode A (6) is smaller than the RF power frequency applied to the cylindrical electrode B (7).
3. Ionization source according to claim 1 or 2, characterized in that:
the two pairs of cylindrical electrodes of the ionization reaction focusing region (9) are applied with radio frequency voltage and direct current voltage U1 with opposite phases;
the two pairs of cylindrical electrodes of the ion transmission area (10) are applied with radio frequency voltage and direct current voltage U2 with opposite phases;
the ion extraction electrode (8) is applied with a direct-current voltage U3;
during positive ion detection, the potentials of the direct current voltages U1, U2 and U3 gradually decrease; during anion detection, the potentials of the direct current voltages U1, U2 and U3 gradually rise.
4. Use of an ionization source according to any one of claims 1 to 3 in mass spectrometry or ion mobility spectrometry.
5. The use according to claim 4, characterized in that:
the ionization source and mass spectrum or ion mobility spectrometry are combined, so that the focal point size of ions can be reduced, and the ion transmission efficiency and detection sensitivity when passing through sampling micropores are improved.
CN202111493713.2A 2021-12-08 2021-12-08 High-efficiency space focusing VUV ionization source Pending CN116246933A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111493713.2A CN116246933A (en) 2021-12-08 2021-12-08 High-efficiency space focusing VUV ionization source

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202111493713.2A CN116246933A (en) 2021-12-08 2021-12-08 High-efficiency space focusing VUV ionization source

Publications (1)

Publication Number Publication Date
CN116246933A true CN116246933A (en) 2023-06-09

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202111493713.2A Pending CN116246933A (en) 2021-12-08 2021-12-08 High-efficiency space focusing VUV ionization source

Country Status (1)

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