High-resolution coaxial speed imaging device

Abstract

The invention provides a high-resolution coaxial speed imaging device, and relates to the field of energy spectrum analysis equipment. The high-resolution coaxial speed imaging device provided by the invention comprises an analysis cavity, a gas sampling mechanism, a vacuum mechanism, an electrostatic lens and an image acquisition mechanism, one end of the analysis cavity is provided with a light inlet window suitable for allowing laser to pass through, and the image acquisition mechanism penetrates through one end of the analysis cavity and is communicated with an inner cavity of the analysis cavity; the gas sampling mechanism and the vacuum mechanism are both arranged on the side wall of the analysis cavity and are both communicated with an inner cavity of the analysis cavity, and the electrostatic lens is arranged in the inner cavity of the analysis cavity. The light path of the laser, the electrostatic lens and the image acquisition mechanism are located on the same axis, the axis is generally the central axis of the analysis cavity, and a reflector is further arranged in the electrode slice to reflect the laser, so that a momentum distribution image of electrons or ions on a polarization plane can be directly obtained.

Description

Technical Field

[0001] The invention relates to the field of energy spectrum analysis equipment, in particular to a high-resolution coaxial velocity imaging device. Background Art

[0002] In the research field of the interaction between strong lasers and atoms and molecules, the key goal is to obtain information such as the yield, energy distribution, angular distribution and velocity distribution of the product. Velocity imaging technology has become an important technical means to detect molecular microdynamics because it can simultaneously measure these interrelated quantities and reveal the reaction dynamics of atoms and molecules. Velocity imaging spectrometers are also popular because of their simple and easy-to-understand reaction principles, ultra-high energy resolution and 100%×4π full solid angle collection efficiency. They have become standard experimental tools for many atomic and molecular photophysics research groups.

[0003] However, in the design of traditional velocity imaging spectrometers, the polarization plane of the laser is perpendicular to the plane of the detector, and it is impossible to conduct angular distribution experiments of electrons or ions related to polarization. In order to overcome this limitation, coaxial velocity imaging spectrometers came into being. During the use of this velocity imaging spectrometer, the laser propagates along the axis of the spectrometer, and the polarization plane of the laser is parallel to the plane of the detector. Compared with traditional velocity imaging spectrometers, coaxial velocity imaging spectrometers can easily and accurately obtain angular distribution images of electrons or ions on the polarization plane, and show significant advantages in laser experiments involving multiple polarization characteristics. However, although the coaxial velocity imaging spectrometer can collect momentum distribution images on the polarization plane of the laser, the image acquisition mechanism it uses cannot withstand the energy of direct laser irradiation, so a specially customized image acquisition mechanism must be used to make way for the laser. This image acquisition mechanism is not only expensive but also very complex in structure, and is usually not adjusted after a single installation.

[0004] In summary, there is a need for a coaxial velocity imaging spectrometer that can avoid direct laser radiation. Summary of the invention

[0005] In order to solve the above problems, the invention provides a high-resolution coaxial velocity imaging device, which can reflect laser light and directly obtain the momentum distribution image of electrons or ions on the laser polarization plane.

[0006] The present invention provides a high-resolution coaxial velocity imaging device, comprising an analysis chamber, a gas injection mechanism, a vacuum mechanism, an electrostatic lens and an image acquisition mechanism; one end of the analysis chamber is provided with a light inlet window suitable for allowing laser light to pass through, the image acquisition mechanism passes through one end of the analysis chamber and is connected to the inner cavity of the analysis chamber; the gas injection mechanism and the vacuum mechanism are both arranged on the side wall of the analysis chamber and are both connected to the inner cavity of the analysis chamber, the electrostatic lens is arranged in the inner cavity of the analysis chamber; the electrostatic lens comprises a first electrode sheet group, a second electrode sheet group and a second electrode sheet group arranged in sequence along the axial direction of the analysis chamber. The first electrode sheet group and the third electrode sheet group, the first electrode sheet group is close to the light inlet window; the first electrode sheet group, the second electrode sheet group and the third electrode sheet group each include a plurality of electrode sheets, each of which is provided with a through hole; the gas injection mechanism includes a gas cylinder, an air inlet pipe assembly and a hollow needle connected in sequence, the hollow needle is located between two electrode sheets in the second electrode sheet group; a metal mesh is also provided in the through hole of the electrode sheet in the second electrode sheet group close to the third electrode sheet group, and a reflector is also provided on the metal mesh; the optical path of the laser, the reflector and the image acquisition mechanism are located on the same axis.

[0007] In a feasible embodiment of the present invention, a fixing rod is further provided in the inner cavity of the analysis chamber, and the fixing rod is sequentially passed through all the electrode sheets; a plurality of fixing nuts and a plurality of isolation washers are also provided on the fixing rod, wherein two of the fixing nuts are respectively located at the two ends of the fixing rod and all the electrode sheets are located between the two fixing nuts, and one or more isolation washers are provided between adjacent electrode sheets.

[0008] In a feasible embodiment of the present invention, the thickness of the isolation gasket is 1 to 5 mm; and / or, the thickness of the electrode sheet is 1 to 136 mm; and / or, the diameter of the opening in the electrode sheet is 15 to 88 mm; and / or, the transmittance of the metal mesh is ≥80%, the mesh number of the metal mesh is ≥180 mesh, and the wire diameter of the metal mesh is ≤0.015 mm; and / or, the thickness of the reflector is 1 to 3 mm, and the diameter of the reflector is 5 to 15 mm; and / or, the materials of the fixing rod, fixing nut and isolation gasket are all ceramic.

[0009] In a feasible embodiment of the present invention, the first electrode sheet group includes N electrode sheets, and the first electrode sheet group is used to protect the uniform electric field; the second electrode sheet group includes M electrode sheets, and the second electrode sheet group is used to form a uniform electric field; the third electrode sheet group includes P electrode sheets, and the third electrode sheet group is used to form a drift electric field; wherein N, M and P satisfy the following relationship

[0010] 4≤N+M+P≤16

[0011] 1≤N≤2, 2≤M≤8, 1≤P≤6.

[0012] In a feasible embodiment of the present invention, the first electrode sheet group includes 2 electrode sheets, namely electrode sheet No. 1 and electrode sheet No. 2; the second electrode sheet group includes 8 electrode sheets, namely electrode sheet No. 3 to electrode sheet No. 11; the third electrode sheet group includes 6 electrode sheets, namely electrode sheet No. 12 to electrode sheet No. 16; a drift tube is also provided in the electrode sheet No. 16; the hollow needle is located between electrode sheet No. 5 and electrode sheet No. 6; one or more resistors are provided between each of the electrode sheets No. 3 to No. 10; metal meshes are provided in the through holes of the electrode sheets No. 11 and No. 12, and a metal mesh is also provided in the through hole of the electrode sheet No. 6 near the image acquisition mechanism, and the reflector is provided on the metal mesh of the electrode sheet No. 11; the electrode sheets No. 1 to No. 3 and the electrode sheets No. 11 to No. 16 are all individually connected to high-voltage connectors.

[0013] In a feasible embodiment of the present invention, the thickness of electrode sheet No. 1 to electrode sheet No. 3 is 1mm, and the diameter of the through hole is 15mm; the thickness of electrode sheet No. 8 to electrode sheet No. 10 is 1mm, and the diameter of the through hole is 88mm; the thickness of electrode sheet No. 11 to electrode sheet No. 15 is 4mm, and the diameter of the through hole is 88mm; the total thickness of electrode sheet No. 16 is 131mm, the thickness of the drift tube is 123mm, the thickness of electrode sheet No. 16 located at both ends of the drift tube is 8mm, and the through hole diameter of electrode sheet No. 16 and the inner diameter of the drift tube are both 88mm; the transmittance of the metal mesh is 80%, the material of the metal mesh is 316L stainless steel, the mesh number of the metal mesh is 180 mesh, and the wire diameter of the metal mesh is 0.015mm; the diameter of the reflector is 10mm, the thickness is 0.3mm, the substrate of the reflector is silicon dioxide, the surface of the substrate is fully gold-plated, the front side is gold-plated with 150nm, and the side and back sides are gold-plated with 20nm.

[0014] In a feasible embodiment of the present invention, a magnetic shielding mechanism is also provided in the inner cavity of the analysis cavity, and the magnetic shielding mechanism includes a first magnetic shielding cavity, a second magnetic shielding cavity and a third magnetic shielding cavity arranged in sequence from the inside to the outside; the electrostatic lens is arranged in the first magnetic shielding cavity.

[0015] In a feasible embodiment of the present invention, the gas injection mechanism also includes a three-dimensional movable platform, the air intake pipe assembly includes a 1 / 4 inch tube and a 1 / 8 inch tube connected and communicated in sequence, one end of the 1 / 8 inch tube is connected and communicated with a hollow needle; the three-dimensional movable platform is arranged outside the 1 / 4 inch tube and connected to the 1 / 4 inch tube.

[0016] In a feasible implementation manner of the present invention, the image acquisition mechanism includes an MCP, a fluorescent screen and a camera which are sequentially arranged along the axial direction of the analysis cavity, and the MCP is close to the third electrode sheet group.

[0017] The present invention also provides a method for using a high-resolution coaxial velocity imaging device, which comprises at least the following steps:

[0018] 1) The laser enters the inner cavity of the analysis chamber through the light inlet window, and ionizes the sample molecules sprayed by the gas injection device in the reaction area to generate electrons and ions;

[0019] 2) The sample molecules are ionized to generate electrons and ions, which are focused on the image acquisition mechanism under the action of the electrostatic lens and are acquired by the image acquisition mechanism.

[0020] The high-resolution coaxial velocity imaging device provided by the present invention has the following beneficial effects:

[0021] 1) The optical path of the laser, the electrostatic lens and the image acquisition mechanism in the present invention are located on the same axis, which is usually the central axis of the analysis cavity, and a reflector is also provided in the electrode sheet to reflect the laser, so that the momentum distribution image of the electron or ion on the polarization plane can be directly obtained; at the same time, the structure of the present invention is not complicated, and the overall modularization is adopted, which relatively simplifies the difficulty of installation, operation and debugging.

[0022] 2) In a specific embodiment of the present invention, there are a total of 16 electrodes, and the voltage of each electrode is carefully designed to more accurately control the flight trajectory of electrons and ions, with a resolution of 1%@60eV.

[0023] 3) The present invention provides a first magnetic shielding cavity, a second magnetic shielding cavity and a third magnetic shielding cavity, which are assembled together using stainless steel screws and pads without contacting each other, so that the residual magnetism of the reaction area is less than 1mGs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0025] Figure 2 It is a cross-sectional view of the overall structure of the present invention.

[0026] Figure 3 It is a side view of the fixing rod and the electrostatic lens in the present invention.

[0027] Figure 4 Schematic diagram of the fixed rod and electrostatic lens in the present invention.

[0028] Figure 5 It is a schematic diagram of the structure of the electrode sheet in the present invention.

[0029] Figure 6 This is the momentum distribution image on the laser polarization plane captured by the present invention.

[0030] Reference numerals

[0031] Analysis chamber 1

[0032] Light intake window 11

[0033] Fixed rod 12

[0034] Fixing nut 13

[0035] Isolation washer 14

[0036] Gas injection mechanism 2

[0037] Cylinder 21

[0038] Intake pipe assembly 22

[0039] Hollow needle 23

[0040] 3D Mobile Platform 24

[0041] Vacuum mechanism 3

[0042] Image acquisition mechanism 4

[0043] MCP 41

[0044] Fluorescent screen 42

[0045] Camera 43

[0046] Reflector 5

[0047] Magnetic shielding mechanism 6

[0048] The first magnetic shielding cavity 61

[0049] The second magnetic shielding cavity 62

[0050] The third magnetic shielding cavity 63

[0051] Drift tube 7

[0052] The first electrode sheet group EpG1

[0053] The second electrode sheet group EpG2

[0054] The third electrode group EpG3

[0055] Electrode sheet Ep DETAILED DESCRIPTION

[0056] The technical solutions in the embodiments of the present invention will be described clearly and completely 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. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the scope of protection of the present invention. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "left side", "right side", "upper side", "lower side", "above", "below" and the like is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0059] Before describing the embodiment of the present invention, the mechanism of the velocity imaging spectrometer is briefly introduced: in the velocity imaging spectrometer, the sample molecules will contact the laser at the focus of the laser and be ionized by the laser, thereby generating electrons and ions, and the target electrons or ions will be captured by the image acquisition mechanism 4 under the action of the electrostatic lens; in the above process, the ionization area where the sample molecules contact the laser focus is called the reaction area. As an illustration, although the sample molecules will generate electrons and ions at the same time when they are ionized, only one can be selected in the same experiment to capture electrons or ions. Polarization plane of laser: refers to the direction of oscillation of the laser electric field. In the laser, the oscillation of the electric field can be confined to a specific plane, which is the so-called polarization plane. For a linearly polarized laser, its electric field is confined to a single plane, along the direction of laser propagation. This means that if you observe the laser beam, you will see that the electric field oscillates in a fixed plane, which is perpendicular to the propagation direction of the laser. The polarization plane is an important parameter to describe the polarization state of the laser beam, because it determines the characteristics of the interaction between the laser and the material, such as in the fields of material processing, optical measurement and communication.

[0060] The embodiment of the present invention provides a high-resolution coaxial velocity imaging device, referring to Figure 1 and Figure 2 , including an analysis chamber 1, a gas sampling mechanism 2, a vacuum mechanism 3, an electrostatic lens and an image acquisition mechanism 4; a light inlet window 11 is provided at one end of the analysis chamber 1, a laser emitter is usually installed outside the analysis chamber 1, the laser emitter is used to emit laser light and the laser light enters the analysis chamber 1 from the light inlet window 11, the image acquisition mechanism 4 passes through one end of the analysis chamber 1 and is connected to the inner cavity of the analysis chamber 1; the gas sampling mechanism 2 and the vacuum mechanism 3 are both arranged on the side wall of the analysis chamber 1 and are both connected to the inner cavity of the analysis chamber 1, the electrostatic lens is arranged in the inner cavity of the analysis chamber 1, and the vacuum mechanism 2 can usually be a combination of a molecular pump and a dry pump. Continue reading Figure 3 The electrostatic lens includes a first electrode sheet group EpG1, a second electrode sheet group EpG2 and a third electrode sheet group EpG3 which are sequentially arranged along the axial direction of the analysis chamber 1. The first electrode sheet group EpG1 is close to the light-entry window 11. The first electrode sheet group EpG1, the second electrode sheet group EpG2 and the third electrode sheet group EpG3 each include a plurality of electrode sheets Ep, each of which is provided with a through hole. For illustration, the electrode sheets Ep are essentially the same, but are divided into a plurality of groups because of their different functions. The first electrode sheet group EpG1 is used to protect the uniform electric field generated by the second electrode sheet group EpG2, the second electrode sheet group EpG2 is used to form a uniform electric field, and the third electrode sheet group EpG3 is used to form a drift electric field. Continue reading Figure 1 The gas injection mechanism 2 includes a gas cylinder 21, an air inlet pipe assembly 22 and a hollow needle 23 connected in sequence, and the hollow needle 23 is located between two electrode sheets Ep in the second electrode sheet group EpG2. In a specific embodiment, the gas injection mechanism 2 and the vacuum mechanism 3 are coaxially arranged, and the axis is usually a diameter of the analysis chamber 1. In a preferred embodiment, as Figure 1 As shown, in order to make the gas beam ejected from the hollow needle 23 hit the blades of the molecular pump (the vacuum mechanism 3 usually includes a molecular pump, and the molecular pump is connected to the analysis chamber 1), there is a certain offset between the molecular pump and the gas injection mechanism 2 in the axial direction of the analysis chamber 1. Figure 1, a metal mesh is also provided in the through hole of the electrode sheet Ep near the third electrode sheet group EpG3 in the second electrode sheet group EpG2, and a reflector 5 is also provided on the metal mesh; the optical path of the laser, the reflector 5 and the image acquisition mechanism 4 are all located on the same axis, which is usually the central axis of the analysis cavity 1. As an explanation, the function of the reflector 5 is to reflect the laser beam. Generally speaking, the image acquisition mechanism 4 cannot withstand the intensity of the laser. Therefore, as mentioned in the background technology, most of the current laser incident directions are perpendicular to the axial direction of the analysis cavity 1 to avoid the image acquisition mechanism 4 being directly irradiated by the laser, or although the momentum distribution image on the laser polarization plane can be collected in the coaxial velocity imaging mechanism, the conventional image acquisition mechanism 4 cannot withstand the energy of the laser, so a specially customized image acquisition mechanism 4 must be used. This image acquisition mechanism 4 is not only expensive but also very complex in structure, and is usually not adjusted after a single installation. Therefore, the role of the reflector 5 in the present invention is crucial. The reflector 5 can reflect the laser back to prevent the laser from directly irradiating the image acquisition mechanism 4. At the same time, because the optical path of the laser and the image acquisition mechanism 4 are located on the same axis, the momentum distribution image of the electron or ion on the polarization plane can be directly obtained. In summary, the optical path of the laser, the electrostatic lens and the image acquisition mechanism 4 in the present invention are located on the same axis, which is usually the central axis of the analysis cavity 1, and the electrode sheet Ep is also provided with a reflector 5 to reflect the laser, so that the momentum distribution image of the electron or ion on the polarization plane can be directly obtained; at the same time, the structure of the present invention is not complicated, and the overall modularization is adopted, which relatively simplifies the difficulty of installation, operation and debugging.

[0061] The high-resolution coaxial velocity imaging device provided by the embodiment of the present invention is referred to Figure 3 The inner cavity of the analysis chamber 1 is also provided with a fixing rod 12, and the fixing rod 12 is sequentially inserted into all the electrode sheets Ep. The fixing rod 12 is also provided with a plurality of fixing nuts 13 and a plurality of isolation washers 14, wherein two fixing nuts 13 are respectively located at the two ends of the fixing rod 12 and all the electrode sheets Ep are located between the two fixing nuts 13, and one or more isolation washers 14 are provided between adjacent electrode sheets Ep. In a specific embodiment, refer to Figure 3 and Figure 4 , including four fixing rods 12, the four fixing rods 12 are simultaneously arranged in all electrode sheets Ep, preferably, the four fixing rods 12 can be used as four vertices of a rectangle on a radial plane, and the electrode sheet Ep is also provided with mounting holes matching the outer diameters of the four fixing rods 12, and in terms of the radial plane facing the electrode sheet Ep, the mounting holes in each electrode sheet Ep are respectively located at the upper left, lower left, upper right and lower right of the electrode sheet Ep, and the through hole is located at the center of the electrode sheet Ep, for details, please refer to Figure 3 and Figure 4When installing the electrode sheet Ep, first install a fixing nut 13 to one end of the fixing rod 12, then install the electrode sheet Ep and the isolation gasket 14 in sequence, until all the electrode sheets Ep and the isolation gaskets 14 are installed, and then install another fixing nut 13 to the other end of the fixing rod 12. After the installation is completed, the electrode sheet Ep is completely fixed on the fixing rod 12 and cannot move, and the centers of all the electrode sheets Ep are located on the same axis, which is usually the central axis of the analysis chamber 1. Here, we briefly explain how the fixing rod 12 is installed in the inner cavity of the analysis chamber 1, see Figure 2 and Figure 3 The end of the fixing rod 12 is connected to a multi-stage flange, and the flanges are assembled by screws and nuts, and the centers of all flanges are located on the same axis, which is usually the central axis of the analysis chamber 1. The outermost large flange in the multi-stage flange is installed to one end of the analysis chamber 1, so that the fixing rod 12 is in the inner cavity of the analysis chamber 1. In addition, some components in the image acquisition mechanism 4 (not mentioned above, see below for details), such as: MCP41 and fluorescent screen 42 are located in the opening in the middle of the multi-stage flange.

[0062] In the high-resolution coaxial velocity imaging device provided in the embodiment of the present invention, the first electrode sheet group EpG1 includes N electrode sheets Ep, and the first electrode sheet group EpG1 is used to protect the uniform electric field generated by the second electrode sheet group EpG2; the second electrode sheet group EpG2 includes M electrode sheets Ep, and the second electrode sheet group EpG2 is used to form a uniform electric field; the third electrode sheet group EpG3 includes P electrode sheets Ep, and the third electrode sheet group EpG3 is used to form a drift electric field; wherein N, M and P satisfy the following relationship,

[0063] 4≤N+M+P≤16

[0064] 1≤N≤2, 2≤M≤8, 1≤P≤6.

[0065] In the high-resolution coaxial velocity imaging device provided in the embodiment of the present invention, following the above embodiment, the number of N is 2, the number of M is 8, and the number of P is 6, that is, the first electrode sheet group EpG1 includes 2 electrode sheets Ep, namely electrode sheet No. 1 Ep and electrode sheet No. 2 Ep, the second electrode sheet group EpG2 includes 8 electrode sheets Ep, namely electrode sheets No. 3 Ep to No. 11 Ep, the third electrode sheet group EpG3 includes 6 electrode sheets Ep, namely electrode sheets No. 12 Ep to No. 16 Ep, and the electrode sheet No. 16 is also provided with a drift tube 7, which can be specifically as follows Figure 3 Continue reading Figure 1 to Figure 3The hollow needle 23 is located between electrode sheet No. 5 Ep and electrode sheet No. 6 Ep. One or more resistors are arranged between electrode sheets No. 3 Ep to No. 10 Ep. Metal meshes are arranged in the through holes of electrode sheets No. 11 Ep and No. 12 Ep. A metal mesh is also arranged in the through hole of electrode sheet No. 16 Ep near the end of image acquisition mechanism 4. A reflector 5 is arranged on the metal mesh of electrode sheet No. 11 Ep. Electrode sheets No. 1 to Ep No. 3 and electrode sheets No. 11 to Ep No. 16 are all connected to external high-voltage connectors separately.

[0066] In the high-resolution coaxial velocity imaging device provided by the embodiment of the present invention, following the above embodiment, the thickness of the isolation gasket 14 is 1-5 mm; and / or, the thickness of the electrode sheet Ep is 1-136 mm; and / or, the diameter of the opening in the electrode sheet Ep is 15-88 mm; and / or, the transmittance of the metal mesh is ≥80%, the mesh number of the metal mesh is ≥180 mesh, and the wire diameter of the metal mesh is ≤0.015 mm; and / or, the thickness of the reflector 5 is 1-3 mm, the diameter of the reflector 5 is 5-15 mm, and the diameter of the reflector 5 should be smaller than the diameter of the opening in the electrode sheet EP; and / or, the materials of the fixing rod 12, the fixing nut 13 and the isolation gasket 14 are all ceramics. Through the design of the above metal mesh and the reflector 5, not only can the laser be smoothly reflected out of the analysis cavity 1, but also the interference and distortion of the electron or ion angular distribution caused by the support of the reflector 5 (that is, the metal mesh) is significantly reduced.

[0067] In a specific embodiment, the thickness of electrode sheet No. 1 Ep to electrode sheet No. 3 is 1 mm, and the diameter of the through hole is 15 mm; the thickness of electrode sheet No. 4 Ep to electrode sheet No. 7 is 1 mm, and the diameter of the through hole is 76 mm; the thickness of electrode sheet No. 8 Ep to electrode sheet No. 10 is 1 mm, and the diameter of the through hole is 88 mm; the thickness of electrode sheet No. 11 Ep to electrode sheet No. 15 is 4 mm, and the diameter of the through hole is 88 mm; the total thickness of electrode sheet No. 16 Ep is 131 mm, the thickness of drift tube 7 is 123 mm, and the thickness of electrode sheet No. 16 Ep at both ends of drift tube 7 is 8 mm. The through hole diameter of electrode sheet Ep No. 16 and the inner diameter of drift tube 7 are both 88mm. The through holes of electrode sheet Ep No. 11, electrode sheet Ep No. 12 and electrode sheet Ep No. 16 near image acquisition mechanism 4 are all provided with a metal mesh with a transmittance of 80%, a material of 316L stainless steel, a mesh number of 180 and a wire diameter of 0.015mm. The metal mesh can shield the adjacent electric field. A reflector 5 is provided on the metal mesh of electrode sheet Ep No. 11. The reflector 5 has a diameter of 10mm and a thickness of 0.3mm. The substrate is silicon dioxide. The substrate surface is fully gold-plated, with 150nm gold-plated on the front and 20nm gold-plated on the side and back. In addition, refer to Figure 3, 3 isolation washers 14 are arranged between electrode sheet 1 Ep and electrode sheet 2 Ep, 2 isolation washers 14 are arranged between electrode sheet 2 Ep and electrode sheet 3 Ep, and only one ceramic washer is arranged between every two adjacent electrode sheets Ep, and the thickness of each ceramic washer is 3 mm. 10MΩ resistors are connected between electrode sheets 3 Ep to 5 Ep, and electrode sheets 6 to 10 Ep, and two 10MΩ resistors are connected between electrode sheets 5 Ep to 6 Ep. When in use, a negative voltage is applied to electrode sheet 3 Ep, and a positive voltage is applied to electrode sheet 10 Ep. By voltage division, a uniform electric field setting between electrode sheet 3 Ep and electrode sheet 10 Ep can be achieved, which can save 6 high-voltage electrode joints and can conveniently control the voltage of all electrode sheets Ep. Furthermore, by performing simulation in a computer, the voltage values ​​required for each of the 16 electrode sheets Ep can be obtained. As an illustration, the flight trajectory of the product particles is controlled by an electrostatic lens. By adjusting the voltage applied to the 16 electrode sheets Ep, the flight trajectory of the electrons or ions can be controlled, that is, the working mode of the electrostatic lens is changed to achieve the purpose of focusing the electrons or ions. The voltage of each electrode in this embodiment is carefully designed, which can more accurately control the flight trajectory of electrons and ions, and the resolution can reach 1%@60eV.

[0068] 4) In the high-resolution coaxial velocity imaging device provided in the embodiment of the present invention, refer to Figure 1 and Figure 2A magnetic shielding mechanism 6 is also provided in the inner cavity of the analysis cavity 1, and the magnetic shielding mechanism 6 includes a first magnetic shielding cavity 61, a second magnetic shielding cavity 62 and a third magnetic shielding cavity 63 which are arranged in sequence from the inside to the outside; the electrostatic lens is arranged in the first magnetic shielding cavity 61. Specifically, the central axes of the first magnetic shielding cavity 61, the second magnetic shielding cavity 62 and the third magnetic shielding cavity 63 all coincide with the central axis of the analysis cavity 1, the inner diameters of the first magnetic shielding cavity 61, the second magnetic shielding cavity 62 and the third magnetic shielding cavity 63 decrease step by step, and they are combined with screws and pads made of stainless steel or aluminum alloy, so that magnetic flux lines do not flow between each other. The material of the first magnetic shielding cavity 61, the second magnetic shielding cavity 62 and the third magnetic shielding cavity is generally Permalloy (1J85), which has higher initial magnetic permeability and maximum magnetic permeability, higher saturation magnetic induction intensity and lower coercive force under weak magnetic field, and its magnetic properties are less sensitive to external interference factors, so it is widely used in magnetic field shielding engineering design. As an illustration, in addition to the electric field, the product particles emitted by the source region are not only pulled by the electric field of the electrostatic lens on the way to the detector, but also disturbed by the stray magnetic field in space (the earth's magnetic field and the magnetic field generated by electrical appliances, etc.). For high-resolution spectrometers, the influence of these stray magnetic fields on the flight trajectory of photoelectrons cannot be ignored. Therefore, in the high-resolution speed imaging device provided by the present invention, the electrode sheet Ep, the fixed rod 12, the fixed nut 13 and the isolation washer 14 are all made of non-magnetic and vacuum-friendly materials, such as aluminum alloy, stainless steel or ceramic. Preferably, the fixed rod 12, the isolation washer 14 and the fixed nut 13 are made of ceramic material, and the electrode sheet Ep is made of aluminum alloy. The first magnetic shielding cavity, the second magnetic shielding cavity and the third magnetic shielding cavity in the present invention are combined with stainless steel screws and pads between each other, and do not contact each other, so that the residual magnetism of the reaction area is less than 1mGs.

[0069] In the high-resolution coaxial velocity imaging device provided in the embodiment of the present invention, referring to Figure 1The gas injection mechanism 2 also includes a three-dimensional mobile platform 24. The gas inlet pipe assembly 22 includes a micro-leak valve, a 1 / 4-inch tube and a 1 / 8-inch tube that are connected and communicated in sequence. One end of the 1 / 8-inch tube is connected and communicated with a hollow needle 23. The three-dimensional mobile platform 24 is arranged outside the 1 / 4-inch tube and connected to the 1 / 4-inch tube. The three-dimensional mobile platform 24 can usually be a three-dimensional mobile platform 24 with a model of TTX63-100-100-S from Kurt J.Lesker Company. The 1 / 4-inch tube can be welded to the flange of the three-dimensional mobile platform 24. As an illustration, the micro-leak valve and the gas cylinder 21 are located outside the analysis chamber 1. When the gas injection mechanism 2 is in use, the sample molecules flow out from the gas cylinder 21, and the size of the gas flow is controlled by the micro-leak valve. After passing through the 1 / 4-inch tube and the 1 / 8-inch tube, the sample molecules are sprayed into the analysis chamber 1 from the end of the hollow needle 23. The background vacuum degree in the inner cavity of the analysis chamber 1 can reach 5×10 -10 mbar, so the gas ejected from the end of the hollow needle 23 enters the inner cavity of the analysis chamber 1 by adiabatic expansion. The material of the analysis chamber 1 is usually stainless steel, preferably 316L stainless steel. In a specific embodiment, the hollow needle 23 is made of stainless steel, with an outer diameter of 0.2 mm and an inner diameter of 0.09 mm.

[0070] In the high-resolution coaxial velocity imaging device provided in the embodiment of the present invention, referring to Figure 1 and Figure 2 The image acquisition mechanism 4 includes MCP41, a fluorescent screen 42 and a camera 43 arranged in sequence along the axial direction of the analysis chamber 1, and the MCP41 is close to the third electrode sheet group EpG3. The gas ejected from the end of the hollow needle 23 intersects the laser perpendicularly at the laser focus (reaction zone, usually located between the No. 5 electrode sheet Ep and the No. 6 electrode sheet Ep), the sample molecules are ionized by the laser, and electrons and ions are generated. The target electrons or ions are focused on the MCP41 under the action of the electrostatic lens. The charged particles collide with the MCP41, and the signal will be amplified. The amplified signal bombards the fluorescent screen 42 behind the MCP41, and fluorescent bright spots will be generated. The distribution images of these bright spots are photographed and recorded by the camera 43, which is the original image generated by the sample ionized by the laser. As an illustration, the MCP41 is a microchannel plate, and the microchannel plate (MCP Micro Channel Plate) is a particle multiplication detector with high spatial resolution.

[0071] The present invention also provides a method for using a high-resolution coaxial velocity imaging device, which comprises at least the following steps:

[0072] 1) The laser enters the inner cavity of the analysis chamber 1 through the light inlet window 11, and ionizes the sample molecules injected by the gas injection device 2 in the reaction area to generate electrons and ions;

[0073] 2) The sample molecules are ionized to generate electrons and ions, which are focused on the image acquisition mechanism 4 under the action of the electrostatic lens and are collected by the image acquisition mechanism 4. Figure 6 This is an image of the momentum distribution of electrons or ions captured by the present invention on the polarization plane of the laser.

[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A high-resolution coaxial velocity imaging device, characterized in that: It comprises an analysis chamber (1), a gas sampling mechanism (2), a vacuum mechanism (3), an electrostatic lens and an image acquisition mechanism (4); One end of the analysis chamber (1) is provided with a light intake window (11) suitable for allowing laser light to pass through; the image acquisition mechanism (4) passes through one end of the analysis chamber (1) and is connected to the inner cavity of the analysis chamber (1); the gas injection mechanism (2) and the vacuum mechanism (3) are both arranged on the side wall of the analysis chamber (1) and are both connected to the inner cavity of the analysis chamber (1); the electrostatic lens is arranged in the inner cavity of the analysis chamber (1); The electrostatic lens comprises a first electrode sheet group (EpG1), a second electrode sheet group (EpG2) and a third electrode sheet group (EpG3) which are sequentially arranged along the axial direction of the analysis chamber (1), wherein the first electrode sheet group (EpG1) is close to the light entrance window (11); the first electrode sheet group (EpG1), the second electrode sheet group (EpG2) and the third electrode sheet group (EpG3) each comprise a plurality of electrode sheets (Ep), and each of the electrode sheets (Ep) is provided with a through hole; The gas sampling mechanism (2) comprises a gas cylinder (21), an air inlet pipe assembly (22) and a hollow needle (23) which are connected in sequence, and the hollow needle (23) is located between two electrode sheets (Ep) in the second electrode sheet group (EpG2); A metal mesh is also provided in the through hole of the electrode sheet (Ep) in the second electrode sheet group (EpG2) close to the third electrode sheet group (EpG3), and a reflector (5) is also provided on the metal mesh; the optical path of the laser, the reflector (5) and the image acquisition mechanism (4) are located on the same axis.

2. The high-resolution coaxial velocity imaging device according to claim 1, characterized in that: A fixing rod (12) is also provided in the inner cavity of the analysis chamber (1), and the fixing rod (12) is sequentially inserted into all the electrode sheets (Ep); a plurality of fixing nuts (13) and a plurality of isolation washers (14) are also provided on the fixing rod (12), wherein two fixing nuts (13) are respectively located at two ends of the fixing rod (12) and all the electrode sheets (Ep) are located between the two fixing nuts (13), and one or more isolation washers (14) are provided between adjacent electrode sheets (Ep).

3. The high-resolution coaxial velocity imaging device according to claim 2, characterized in that: The thickness of the isolation gasket (14) is 1 to 5 mm; and / or the thickness of the electrode sheet (Ep) is 1 to 136 mm; and / or the diameter of the opening in the electrode sheet (Ep) is 15 to 88 mm; and / or the transmittance of the metal mesh is ≥80%, the mesh number of the metal mesh is ≥180 mesh, and the wire diameter of the metal mesh is ≤0.015 mm; and / or the thickness of the reflector (5) is 1 to 3 mm, and the diameter of the reflector (5) is 5 to 15 mm; and / or the materials of the fixing rod (12), the fixing nut (13) and the isolation gasket (14) are all ceramic.

4. The high-resolution coaxial velocity imaging device according to claim 1, characterized in that: The first electrode sheet group (EpG1) includes N electrode sheets (Ep), and the first electrode sheet group (EpG1) is used to protect a uniform electric field; the second electrode sheet group (EpG2) includes M electrode sheets (Ep), and the second electrode sheet group (EpG2) is used to form a uniform electric field; the third electrode sheet group (EpG3) includes P electrode sheets (Ep), and the third electrode sheet group (EpG3) is used to form a drift electric field; wherein N, M and P satisfy the following relationship 4≤N+M+P≤16 1≤N≤2, 2≤M≤8, 1≤P≤6.

5. The high-resolution coaxial velocity imaging device according to claim 4, characterized in that: The first electrode sheet group (EpG1) comprises two electrode sheets (Ep), namely electrode sheet No. 1 (Ep) and electrode sheet No. 2 (Ep); the second electrode sheet group (EpG2) comprises eight electrode sheets (Ep), namely electrode sheets No. 3 (Ep) to No. 11 (Ep); the third electrode sheet group (EpG3) comprises six electrode sheets (Ep), namely electrode sheets No. 12 (Ep) to No. 16 (Ep); the electrode sheet No. 16 (Ep) is further provided with a drift tube (7); The hollow needle (23) is located between electrode sheet No. 5 (Ep) and electrode sheet No. 6 (Ep); one or more resistors are provided between each of electrode sheets No. 3 (Ep) to No. 10 (Ep); metal meshes are provided in the through holes of electrode sheets No. 11 (Ep) and No. 12 (Ep); a metal mesh is also provided in the through hole of electrode sheet No. 6 (Ep) near the end of the image acquisition mechanism 4; the reflector (5) is provided on the metal mesh of electrode sheet No. 11 (Ep); electrode sheets No. 1 (Ep) to No. 3 (Ep) and electrode sheets No. 11 (Ep) to No. 16 (Ep) are all individually connected to high-voltage connectors.

6. The high-resolution coaxial velocity imaging device according to claim 5, characterized in that: The thickness of electrode sheet No. 1 (Ep) to electrode sheet No. 3 (Ep) is 1 mm, and the diameter of the through hole is 15 mm; the thickness of electrode sheet No. 8 (Ep) to electrode sheet No. 10 (Ep) is 1 mm, and the diameter of the through hole is 88 mm; the thickness of electrode sheet No. 11 (Ep) to electrode sheet No. 15 (Ep) is 4 mm, and the diameter of the through hole is 88 mm; the total thickness of electrode sheet No. 16 (Ep) is 131 mm, the thickness of drift tube (7) is 123 mm, and the No. 16 electrode sheet located at both ends of drift tube (7) is 131 mm. The thickness of the electrode sheet (Ep) is 8 mm, the through hole diameter of the No. 16 electrode sheet (Ep) and the inner diameter of the drift tube (7) are both 88 mm; the transmittance of the metal mesh is 80%, the material of the metal mesh is 316L stainless steel, the mesh number of the metal mesh is 180 mesh, and the wire diameter of the metal mesh is 0.015 mm; the diameter of the reflector (5) is 10 mm, the thickness is 0.3 mm, the substrate of the reflector (5) is silicon dioxide, the surface of the substrate is fully gold-plated, the front side is gold-plated with 150 nm, and the side and back sides are gold-plated with 20 nm.

7. The high-resolution coaxial velocity imaging device according to claim 1, characterized in that: A magnetic shielding mechanism (6) is also provided in the inner cavity of the analysis cavity (1), and the magnetic shielding mechanism (6) comprises a first magnetic shielding cavity (61), a second magnetic shielding cavity (62), and a third magnetic shielding cavity (63) which are arranged in sequence from the inside to the outside; the electrostatic lens is arranged in the first magnetic shielding cavity (61).

8. The high-resolution coaxial velocity imaging device according to claim 1, characterized in that: The gas injection mechanism (2) also includes a three-dimensional movable platform (24); the gas inlet pipe assembly (22) includes a 1 / 4-inch tube and a 1 / 8-inch tube that are connected and communicated in sequence; one end of the 1 / 8-inch tube is connected and communicated with a hollow needle (23); and the three-dimensional movable platform (24) is arranged outside the 1 / 4-inch tube and connected to the 1 / 4-inch tube.

9. The high-resolution coaxial velocity imaging device according to claim 1, characterized in that: The image acquisition mechanism (4) comprises an MCP (41), a fluorescent screen (42) and a camera (43) which are sequentially arranged along the axial direction of the analysis chamber (1); the MCP (41) is close to the third electrode sheet group (EpG3).

10. A method for using the high-resolution coaxial velocity imaging device according to any one of claims 1 to 9, characterized in that: At least the following steps are included: 1) The laser enters the inner cavity of the analysis chamber (1) through the light entrance window (11), and ionizes the sample molecules injected by the gas injection mechanism (2) in the reaction zone, generating electrons and ions; 2) The sample molecules are ionized to generate electrons and ions, which are focused on the image acquisition mechanism (4) under the action of the electrostatic lens and are collected by the image acquisition mechanism (4).

Images