An anion photoelectron velocity imaging device and method with 45° sampling

Abstract

This invention relates to an anion photoelectron velocity imaging device and method with 45° sampling. The device comprises a mass-selective ion sampling and beam modulation module and a laser-induced photoelectron velocity imaging module. The mass-selective ion sampling and beam modulation module includes a screen electrode plate, a base, and an ion beam modulation section. The screen electrode plate is used to mass-select target ions and change their flight trajectory when a pulse voltage is applied. The ion beam modulation section is used to reduce the beam diameter, adjust the spatial position, and focus the target ions whose motion trajectory has been changed. The laser-induced photoelectron velocity imaging module is used to apply laser-induced electron desorption to the pulsed beam of the mass-selected and beam-modulated target ions, generating photoelectrons. Using the BASEX program, based on the photoelectron position distribution information, the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ions are obtained. This invention can be widely used in the field of photoelectron velocity imaging technology.

Description

Technical Field

[0001] This invention relates to the field of photoelectron velocity imaging technology, and in particular to an anion photoelectron velocity imaging device and method with 45° sampling. Background Technology

[0002] Clusters are relatively stable microscopic aggregates composed of several to thousands of atoms, molecules, or ions bound together by physical or chemical forces. Their physical and chemical properties vary with the number of atoms they contain, representing a new level of material structure between atoms, molecules, and macroscopic solids. The structure of clusters differs from that of solids; the addition or removal of even a single atom or electron can cause structural changes. Gas-phase cluster systems are ideal models for studying chemical reactions and catalytic mechanisms on metal surfaces. Elucidating the evolution of their physicochemical properties with size also contributes to a deeper understanding of the structure-activity relationship of condensed matter.

[0003] Anion photoelectron spectroscopy (PES) is a method that uses the photoelectric effect to measure the energy, intensity, and angular distribution of photoelectrons ejected from a material surface under laser excitation, thereby analyzing the electronic structure and chemical composition of the material surface. In experimental-computational studies, the coupling of PES with mass spectrometry has been widely applied in cluster science to help determine the electronic and geometric structures of mass-selected species. By recording the velocity distribution of cluster ions of mass-selected species, not only can dissociation ionization dynamics be revealed, but additional information about the cluster structure can also be obtained.

[0004] Combining velocity-map imaging (VMI) with cluster reactions and mass spectrometry provides a platform for comprehensively revealing electronic structure and reaction kinetics. However, most commercial time-of-flight mass spectrometers, as well as many custom instruments in the laboratory, operate in upright reflection mode, which presents challenges for integration with VMI instruments. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide an anion photoelectron velocity imaging device and method capable of being coupled with a custom instrument for 45° sampling.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: On the one hand, it provides an anion photoelectron velocity imaging device with 45° sampling, including a mass-selected ion sampling and beam modulation module and a laser-induced photoelectron velocity imaging module;

[0007] The selected ion sampling and beam modulation module includes a screen electrode plate, a base, and an ion beam modulation section. Several screen electrode plates are evenly spaced at 45° angles on the base. The top and bottom screen electrode plates are grounded, while the middle screen electrode plate is connected via a voltage divider resistor. An inlet for the ion beam modulation section is located on one side of the base. The screen electrode plates are used to select the target ions by mass and change their flight trajectory when a pulse voltage is applied. The ion beam modulation section is used to reduce the beam diameter, adjust the spatial position, and focus the target ions whose flight trajectories have been changed.

[0008] The outlet of the ion beam modulation section is connected to the laser-induced photoelectron velocity imaging module. The laser-induced photoelectron velocity imaging module is used to perform laser-induced electron desorption onto the target ion pulse beam after quality selection and beam modulation to generate photoelectrons. Using the BASEX program, the photoelectron velocity distribution, photoelectron kinetic energy spectrum and electron binding energy spectrum of the target ion are obtained based on the photoelectron position distribution information.

[0009] Furthermore, the ion beam modulation section includes an ion beam modulation inlet lens, upper and lower deflection electrodes, a first grounded zero potential plate, left and right deflection electrodes, a second grounded zero potential plate, a first zero potential lens, a focusing lens, and a second zero potential lens.

[0010] One side of the ion beam modulation inlet lens is connected to one side of the base, and the other side of the ion beam modulation inlet lens is connected to the laser-induced photoelectron velocity imaging module in sequence through the coaxial upper and lower deflection electrodes, the first ground zero potential plate, the left and right deflection electrodes, the second ground zero potential plate, the first zero potential lens, the focusing lens, and the second zero potential lens.

[0011] The ion beam modulation inlet lens is used to eliminate stray ions with excessive incident angles, thereby reducing the beam diameter of the target ions.

[0012] The upper and lower deflection electrodes and the left and right deflection electrodes are used to change the orientation of the target ion's flight direction in the vertical and horizontal directions by applying different DC voltages in the vertical and horizontal directions of the target ion's flight direction.

[0013] The first and second grounded zero potential plates are used to block diverging ions.

[0014] The first zero-potential lens, the focusing lens, and the second zero-potential lens are used to focus the target ions after adjusting their spatial position.

[0015] Furthermore, both the first zero-potential lens and the second zero-potential lens are Einzel lenses.

[0016] Furthermore, the laser-induced photoelectron velocity imaging module includes a VMI photoelectron modulation section, a laser device, a magnetic / electric shielding cylinder, a rigid aluminum cylinder support, a fluorescent screen support, a CCD light-shielding cylinder, a CCD support plate, a grounded rigid aluminum cylinder, a photoelectron detector, a CCD camera, and a host computer.

[0017] One side of the VMI photoelectronic modulation section is connected to the second zero-potential lens. The VMI photoelectronic modulation section is provided with an incident window for laser incidence of the laser device. The other side of the VMI photoelectronic modulation section extends into the grounded rigid aluminum cylinder. The VMI photoelectronic modulation section and the grounded rigid aluminum cylinder are fitted with the magnetic / electric shielding cylinder. The other side of the grounded rigid aluminum cylinder is connected to one side of the fluorescent screen support through a rigid aluminum cylinder bracket. The fluorescent screen support is provided with the photoelectronic detector. The other side of the fluorescent screen support is connected to the CCD support plate through the CCD light-shielding cylinder. The microchannel plate, the photoelectronic detector, and the CCD light-shielding cylinder are coaxially arranged. The CCD support plate is provided with the CCD camera, which is also connected to the host computer.

[0018] The laser device is used to emit a desorption laser through the incident window perpendicular to the direction of movement of the target ions, which intersects with the ion beam in the ionization region.

[0019] The VMI photoelectronic modulation section is used to hit the target ion modulated by the ion beam modulation section with the desorption laser to generate photoelectrons of the target ion.

[0020] The grounded rigid aluminum cylinder is used to ensure that desorbed electrons can fly freely in a vacuum without a field.

[0021] The magnetic / electric shielding cylinder is used to shield external influences on spin electrons;

[0022] The photoelectron detector is used to amplify the obtained photoelectron signal and convert it into a fluorescence signal;

[0023] The CCD camera is used to capture fluorescence signals and record photoelectron position distribution information;

[0024] The host computer is used to obtain the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion based on the photoelectron position distribution information using the BASEX program.

[0025] Furthermore, the VMI optoelectronic modulation section includes a sampling reference lens, a sampling beam collimating lens, a grid accelerating electrode plate, a first electrostatic lens plate, a second electrostatic lens plate, a third electrostatic lens plate, a fourth electrostatic lens plate, a fifth electrostatic lens plate, a sixth electrostatic lens plate, a seventh electrostatic lens plate, and an optoelectronic extraction plate arranged sequentially. Among these, every two adjacent plates of the first to seventh electrostatic lens plates are connected by an equal resistance, and an additional DC current is applied to the relevant plates.

[0026] The target ions modulated by the ion beam modulation section enter through the sampling reference lens and are collimated by the sampling beam collimating lens. They are then struck by the desorption laser beam of the laser device at the midpoint between the grid accelerating electrode plate and the first electrostatic lens plate. The photoelectrons generated by photodesorption are accelerated and pushed towards the photoelectron detector through the second, third, fourth, fifth, sixth, and seventh electrostatic lens plates and the photoelectron extraction plate.

[0027] Furthermore, the photoelectron detector includes a microchannel plate and a photoelectron detection fluorescent screen;

[0028] The microchannel plate is used to multiply the photoelectrons of the generated target ions through secondary electrons.

[0029] The photoelectron detection fluorescent screen is used to convert the multiplied photoelectron signal into a fluorescent signal.

[0030] Furthermore, the laser-induced photoelectron velocity imaging module is arranged perpendicularly to or coaxially with the mass-selected ion sampling and beam modulation module.

[0031] Furthermore, when the laser-induced photoelectron velocity imaging module is set perpendicularly to the mass-selected ion sampling and beam modulation module, the mass-selected ion sampling and beam modulation module is set on one side of the vertical laser-induced photoelectron velocity imaging module, corresponding to the position of the axis of the mass-selected ion sampling and beam modulation module. The ion beam, the desorption laser of the laser device, and the laser-induced photoelectron velocity imaging module are orthogonal to each other. A time-of-flight mass spectrometry (MCP) detector for determining the timing of the target ion and the desorption laser is set at the radial end of the ion beam.

[0032] On the other hand, an imaging method based on an anion photoelectron velocity imaging device with 45° sampling is provided, including:

[0033] Apply pulse voltage, and select the target ions by controlling the pulse timing mass selection ion sampling and beam modulation module. Use 45° sampling method to change the ion flight trajectory so that the target ions enter the beam modulation channel of the ion beam modulation section.

[0034] The ion beam modulation section reduces the beam diameter, adjusts the spatial position, and focuses the target ions introduced into the beam modulation channel. The modulated target ions then fly to the laser-induced photoelectron velocity imaging module.

[0035] The laser-induced photoelectron velocity imaging module uses a pulsed laser to induce electron desorption into the target ion pulse beam after quality selection and beam modulation, generating photoelectrons. Using the BASEX program, the module obtains the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion based on the photoelectron position distribution information.

[0036] Furthermore, the laser-induced photoelectron velocity imaging module uses a pulsed laser to perform laser-induced electron desorption onto a mass-selected and beam-modulated target ion pulsed beam, generating photoelectrons. Using the BASEX program, based on the photoelectron position distribution information, it obtains the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion, including:

[0037] The VMI optoelectronic modulation section aligns the quality-selected and beam-modulated target ions with the desorption laser emitted by the laser device in time and space. At the laser desorption point, the target ions interact with the linearly polarized beam to generate optoelectronics.

[0038] The photoelectron detector amplifies the generated photoelectron signal, converts it into a fluorescence signal, records the photoelectron position distribution information, and transmits it to the host computer via optical fiber.

[0039] The host computer uses the BASEX program to transform the photoelectron position distribution information through transpose, Abelian transformation and radial integration to obtain the required photoelectron velocity distribution, photoelectron kinetic energy spectrum and electron binding energy spectrum.

[0040] The present invention has the following advantages due to the adoption of the above technical solutions:

[0041] 1. This invention is at 45 o The ion sampling-based imaging device is designed to be integrated with upright reflectance time-of-flight mass spectrometry (Re-TOFMS) instruments and exhibits good sensitivity and resolution.

[0042] 2. The present invention has two sets of deflection electrodes in the ion beam modulation section. Each set of deflection electrodes consists of two electrode plates, which are located in the four directions of up, down, left and right of the ion movement direction. By applying different DC voltages to the two electrode plates, the ion movement direction can be directionally changed.

[0043] 3. The electrostatic lens set in the ion beam modulation section of this invention is similar in principle to an optical convex lens that can focus light. Ion beams can also be focused by equipotential lines with a specific shape. An Einzel lens is used, which is composed of coaxially arranged metal cylinders. The same voltage (usually grounded) is applied to the first zero potential lens and the second zero potential lens. The focus of the ion lens is adjusted by changing the voltage on the focusing lens.

[0044] 4. This invention provides a compatible switchable laser-induced photoelectron velocity imaging module and two experimental methods: horizontal and orthogonal installation of the ion beam. The choice can be made for different experimental requirements of ion beam intensity and resolution.

[0045] In summary, this invention can be widely applied in the field of photoelectronic velocity imaging technology. Attached Figure Description

[0046] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0047] Figure 1 This is a horizontally mounted cross-sectional view of the laser-induced photoelectron velocity imaging module in an anion photoelectron velocity imaging device provided in an embodiment of the present invention.

[0048] Figure 2 This is a front view of an anion photoelectron velocity imaging device provided in an embodiment of the present invention;

[0049] Figure 3 This is a front view of a laser-induced photoelectron velocity imaging module vertically arranged in an anion photoelectron velocity imaging device provided in an embodiment of the present invention;

[0050] Figure 4 This is a schematic diagram of iodine ion photoelectron velocity imaging and photoelectron spectrum of an anion photoelectron velocity imaging device provided in an embodiment of the present invention.

[0051] Appendix Figure 1 The symbols in the text are represented as follows:

[0052] 1-Screen electrode plate; 2-Triangular base; 3-Ion beam modulation inlet lens; 4-Upper and lower deflection electrodes; 5-First grounding aperture baffle; 6-Left and right deflection electrodes; 7-Second grounding aperture baffle; 8-First zero potential lens; 9-Focusing lens; 10-Second zero potential lens; 11-Sampling reference lens; 12-Magnetic / electric shielding cylinder; 13-Hard aluminum cylinder support; 14-Fluorescent screen support; 15-CCD light shielding cylinder; 16-CCD support plate; 17-Sampling beam collimating lens; 18-Grid accelerating electrode plate; 19-25-Resistive connected stepped voltage divider ion lens electrode plate assembly (i.e., first to seventh electrostatic lens electrode plates); 26-Photoelectron extraction electrode plate; 27-Grounded hard aluminum cylinder; 28-Photoelectron detector.

[0053] Appendix Figure 3 The symbols in the text are represented as follows:

[0054] 1-Sieve electrode plate; 2-Triangular base; 3-Ion beam modulation inlet lens; 4-Upper and lower deflection electrodes; 5-First grounding aperture baffle; 6-Left and right deflection electrodes; 7-Second grounding aperture baffle; 8-First zero potential lens; 9-Focusing lens; 10-Second zero potential lens; 11-Sampling reference lens; 12-Magnetic / electric shielding cylinder; 13-Hard aluminum cylinder support; 14-Fluorescent screen support; 15-CCD light shielding cylinder; 16-CCD support plate; 29-Time-of-flight mass spectrometer (MCP) detector. Detailed Implementation

[0055] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0056] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0057] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0058] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "above," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0059] The anion photoelectron velocity imaging device and method with 45° sampling provided in this invention includes a mass-selected ion sampling and beam modulation module. Figure 1 Components 1-10 in the middle) and laser-induced photoelectron velocity imaging module ( Figure 1 Components 11-28 can be coupled with custom instruments to acquire mass spectra of target anion clusters and alter the trajectory of ions vertically reflected by time-of-flight mass spectra to obtain secondary mass spectra and photoelectron spectra of mass-selected anion clusters.

[0060] Example 1

[0061] like Figure 1 , Figure 2 As shown, this embodiment provides an anion photoelectron velocity imaging device with 45° sampling, including a selective ion sampling and beam modulation module and a laser-induced photoelectron velocity imaging module. The selective ion sampling and beam modulation module includes several screen electrode plates 1, a triangular base 2 and an ion beam modulation part.

[0062] Several screen electrode plates 1 are evenly spaced at a 45° angle on the hypotenuse of a triangular base 2. The top and bottom screen electrode plates 1 are grounded, while the middle screen electrode plates 1 (e.g., three plates) are connected via voltage divider resistors (e.g., the voltages of the three screen electrode plates 1 can be U, 2 / 3U, and 1 / 3U, where U is the sampling voltage set according to the desired deflection cluster). The screen electrode plates 1 are used to perform mass selection on target ions and change their flight trajectory when a pulsed voltage is applied, so that they can enter the downstream ion beam modulation section and the laser-induced photoelectron velocity imaging module. An inlet for the ion beam modulation section is provided on one side of the triangular base 2. The ion beam modulation section is used to reduce the beam diameter, adjust the spatial position, and focus the beam of the introduced target ions.

[0063] The outlet of the ion beam modulation section is connected to the laser-induced photoelectron velocity imaging module. The laser-induced photoelectron velocity imaging module is used to perform laser-induced electron desorption on the target ion pulse beam after quality selection and beam modulation to generate photoelectrons. Using the BASEX program, the photoelectron velocity distribution, photoelectron kinetic energy spectrum and electron binding energy spectrum of the target ion are obtained based on the photoelectron position distribution information.

[0064] In a preferred embodiment, the ion beam modulation section includes an ion beam modulation inlet lens 3, upper and lower deflection electrodes 4, a first grounded zero potential electrode 5, left and right deflection electrodes 6, a second grounded zero potential electrode 7, a first zero potential lens 8, a focusing lens 9, and a second zero potential lens 10.

[0065] One side of the ion beam modulation inlet lens 3 is connected to one side of the triangular base 2. The other side of the ion beam modulation inlet lens 3 is connected to the laser-induced photoelectron velocity imaging module through the coaxial upper and lower deflection electrodes 4, the first ground zero potential plate 5, the left and right deflection electrodes 6, the second ground zero potential plate 7, the first zero potential lens 8, the focusing lens 9, and the second zero potential lens 10.

[0066] The ion beam modulation inlet lens 3 is used to eliminate stray ions with excessive incident angles, thereby reducing the beam diameter of the target ions.

[0067] The vertical deflection electrode 4 and the horizontal deflection electrode 6 are used to adjust the spatial position of the target ions by applying different DC voltages in the vertical and horizontal directions of the target ion flight direction.

[0068] The first grounded zero potential plate 5 and the second grounded zero potential plate 7 are used to block diverging ions, which can regulate the ion beam diameter to a certain extent.

[0069] The first zero-potential lens 8, the focusing lens 9, and the second zero-potential lens 10 are used to properly focus the target ions after adjusting their spatial position, so as to ensure that they have a reasonable beam diameter when they reach the laser-induced photoelectron velocity imaging module.

[0070] Specifically, the first zero-potential lens 8 and the second zero-potential lens 10 are both designed based on the Einzel lens group principle. The lengths of the first zero-potential lens 8 and the second zero-potential lens 10 are 35mm, and the length of the focusing lens 9 is 16mm.

[0071] In a preferred embodiment, the laser-induced photoelectron velocity imaging module includes a VMI photoelectron modulation section, a laser device, a magnetic / electric shielding cylinder 12, a rigid aluminum cylinder support 13, a fluorescent screen support 14, a CCD light-shielding cylinder 15, a CCD support plate 16, a grounded rigid aluminum cylinder 27, a photoelectron detector 28, a CCD camera, and a host computer.

[0072] One side of the VMI photoelectronic modulation section is connected to the second zero-potential lens 10. The VMI photoelectronic modulation section is provided with an incident window for laser incident on the laser device. The other side of the VMI photoelectronic modulation section extends into the grounded rigid aluminum cylinder 27. A magnetic / electric shielding cylinder 12 is sleeved on the outside of the VMI photoelectronic modulation section and the grounded rigid aluminum cylinder 27. The other side of the grounded rigid aluminum cylinder 27 is connected to one side of the fluorescent screen support 14 through the rigid aluminum cylinder bracket 13. A photoelectronic detector 28 is provided on the fluorescent screen support 14. The other side of the fluorescent screen support 14 is connected to the CCD support plate 16 through the CCD light shielding cylinder 15. The microchannel plate, the photoelectronic detector 28 and the CCD light shielding cylinder 15 are coaxially arranged. A CCD camera is provided on the CCD support plate 16. The CCD camera is also connected to the host computer.

[0073] The laser device emits a desorption laser through the incident window perpendicular to the direction of movement of the target ions, which intersects with the ion beam in the ionization region.

[0074] The VMI optoelectronic modulation section is used to hit the target ion, which has been modulated by the ion beam modulation section, with the desorption laser. At the laser desorption point, the target ion interacts with the linearly polarized beam to generate optoelectronics.

[0075] The grounded rigid aluminum cylinder 27 is used to ensure that desorbed electrons can fly freely in a vacuum without a field.

[0076] The magnetic / electric shielding tube 12 is used to shield the spin electrons from external influences.

[0077] The photoelectron detector 28 is used to amplify the obtained photoelectron signal and convert it into a fluorescence signal.

[0078] CCD cameras are used to capture fluorescence signals, record photoelectron position distribution information, and transmit it to a host computer via optical fiber.

[0079] The host computer is used to obtain the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion based on the photoelectron position distribution information using the BASEX program.

[0080] Specifically, the magnetic / electric shielding cylinder 12 can be a permalloy electromagnetic shielding cylinder.

[0081] Specifically, the photoelectron detector 28 includes a microchannel plate (MCP) and a photoelectron detection fluorescent screen. The microchannel plate is used to multiply the photoelectrons of the generated target ions through secondary electrons, resulting in a stronger electron flow. The photoelectron detection fluorescent screen is used to convert the multiplied photoelectron signal into a fluorescence signal. Through the cooperation of the microchannel plate and the photoelectron detection fluorescent screen, the photoelectron position distribution information is obtained.

[0082] Specifically, the CCD camera is protected by three sets of CCD light shields 15 to prevent external light sources from affecting the CCD camera.

[0083] Specifically, the photoelectron detector 28 is located at 270 mm from the sampling reference lens 11.

[0084] In a preferred embodiment, the VMI optoelectronic modulation section includes sampling reference lenses 11 (or L) arranged sequentially. R The system includes a sampling beam collimating lens 17, a grid accelerating electrode plate 18 (or L1, with an applied pulse voltage U1), a first electrostatic lens plate 19 (or L2, with an applied DC voltage U2), a second electrostatic lens plate 20, a third electrostatic lens plate 21 (or L3, with an applied DC voltage U3), a fourth electrostatic lens plate 22, a fifth electrostatic lens plate 23, a sixth electrostatic lens plate 24, a seventh electrostatic lens plate 25 (or L4, grounded or with an applied DC voltage U4), and a photoelectron extraction plate 26 (grounded). Each pair of adjacent plates in the first to seventh electrostatic lens plates 19 to 25 is connected with an equal resistance to achieve a stepped voltage division function. Additional DC voltage is applied to the relevant plates (L1, L2, L3, L4) to improve the photoelectron kinetic energy resolution. The target ions modulated by the ion beam modulation section enter through the sampling reference lens 11 and are collimated by the sampling beam collimating lens 17. They are then struck by the desorption laser beam of the laser device at the midpoint between the grid accelerating electrode plate 18 and the first electrostatic lens plate 19. The photoelectrons generated by photodesorption are accelerated and pushed towards the photoelectron detector 28 through the second electrostatic lens plate 20, the third electrostatic lens plate 21, the fourth electrostatic lens plate 22, the fifth electrostatic lens plate 23, the sixth electrostatic lens plate 24, the seventh electrostatic lens plate 25 and the photoelectron extraction plate 26.

[0085] Specifically, the distance between the grid accelerating electrode plate 18 and the first electrostatic lens plate 19 is greater than the distance between adjacent plates of the subsequent second to seventh electrostatic lens plates 20 to 25, so as to reduce the noise signal generated by the desorption laser acting on the electrostatic lens plate.

[0086] Specifically, the first to seventh electrostatic lens plates 19-25 of the grid accelerating electrode plate 18 are all 1.5 mm thick and 50 mm in outer diameter. The inner diameter of the first electrostatic lens plate 19 is 10 mm, and the inner diameter of the other electrostatic lens plates is 25 mm. The distance between the grid accelerating electrode plate 18 and the first electrostatic lens plate 19 is 13 mm, and the distance between the other electrostatic lens plates is 5 mm. The grid accelerating electrode plate 18 is set to pulsed voltage, and the other electrostatic lens plates are set to regulated DC voltage.

[0087] In a preferred embodiment, such as Figure 1 and Figure 2 As shown, the laser-induced photoelectron velocity imaging module is coaxially arranged with the mass-selected ion sampling and beam modulation module. In this preferred embodiment, both the VMI photoelectron modulation section and the ion flight path are enclosed by a cylinder with a μ metal shielding layer to shield the influence of the Earth's magnetic field on the electron flight path.

[0088] In a preferred embodiment, such as Figure 3 As shown, the laser-induced photoelectron velocity imaging module is vertically positioned with the mass-selected ion sampling and beam modulation module.

[0089] Specifically, the selected ion sampling and beam modulation module is positioned on one side of the vertical laser-induced photoelectron velocity imaging module, corresponding to the axis of the selected ion sampling and beam modulation module. The ion beam, the desorption laser of the laser device, and the laser-induced photoelectron velocity imaging module are orthogonal to each other. A time-of-flight mass spectrometry (TOF-MS) detector 29 is located at the radial end of the ion beam to determine the timing of the target ion and the desorption laser, and to serve as the basis for beam optimization in the ion beam modulation section. More specifically, the TOF-MS detector can be a microchannel plate.

[0090] Example 2

[0091] This embodiment provides a 45° sampling anion photoelectron velocity imaging method, including the following steps:

[0092] 1) Set up the anion photoelectron velocity imaging device with 45° sampling as described in Example 1.

[0093] 2) Apply a suitable pulse voltage, and select the target ion mass by controlling the pulse timing mass selection ion sampling and beam modulation module. Use a 45° sampling method to change the ion flight trajectory so that the target ion is introduced into the beam modulation channel of the ion beam modulation section.

[0094] 3) The ion beam modulation section performs beam diameter reduction, spatial position adjustment, and focusing modulation on the target ions introduced into the beam modulation channel. The modulated target ions then fly to the laser-induced photoelectron velocity imaging module, specifically:

[0095] 3.1) When the target ions enter the ion beam modulation section, they first pass through the ion beam modulation inlet lens 3 to eliminate stray ions with excessive incident angles and reduce the beam diameter of the target ions.

[0096] 3.2) After the beam diameter is reduced, the target ions are deflected by the upper and lower deflection electrodes 4 and the left and right deflection electrodes 6. Different DC voltages are applied in the vertical and horizontal directions of the ion flight direction, so that the flight direction of the target ions is oriented in the vertical and horizontal directions, thereby adjusting the spatial position of the target ions.

[0097] 3.3) By blocking diverging ions through the first grounded zero potential plate 5 and the second grounded zero potential plate 7, the ion beam diameter is regulated to a certain extent.

[0098] 3.4) The target ions after adjusting their spatial position are properly focused by the first zero-potential lens 8, the focusing lens 9 and the second zero-potential lens 10 so as to have a reasonable beam diameter when they reach the laser-induced photoelectron velocity imaging module. The focused target ions fly to the laser-induced photoelectron velocity imaging module.

[0099] 4) The laser-induced photoelectron velocity imaging module uses a pulsed laser (e.g., 10Hz) to induce electron desorption of the target ion pulsed beam (e.g., 10Hz) after mass selection and beam modulation, generating photoelectrons. Using the BASEX program, based on the photoelectron position distribution information, the module obtains the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion. Specifically:

[0100] 4.1) The VMI photoelectronic modulation section aligns the target ions after quality selection and beam modulation with the desorption laser emitted by the laser device in time and space. At the laser desorption point, the target ions interact with the linearly polarized beam to generate photoelectrons.

[0101] Specifically, the grid accelerating electrode plate 18 and the first to seventh accelerating electrode plates 19-25 can be loaded with a fully negative voltage: 0>U3>U2>U1 (pulse), or a combination of positive and negative voltages can be used, for example: U1 (pulse). <U2=0<U3<U4。

[0102] 4.2) The photoelectron detector 28 amplifies the generated photoelectron signal and converts it into a fluorescence signal. After recording the photoelectron position distribution information, it transmits the signal to the host computer via optical fiber.

[0103] 4.3) The host computer uses the BASEX program to obtain the photoelectron velocity distribution, photoelectron kinetic energy spectrum and electron binding energy spectrum of the target ion based on the photoelectron position distribution information.

[0104] Specifically, the BASEX program can transform the photoelectron position distribution information into the desired photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum through transpose, Abelian transformation, and radial integration.

[0105] When the laser-induced photoelectron velocity imaging module is set perpendicular to the mass-selected ion sampling and beam modulation module, step 4.1) is preceded by:

[0106] The time-of-flight mass spectrometer (TOF-MS) MCP detector 29 provides real-time monitoring as an aid, optimizing the target ion deflection voltage adjustment at the beam front end and applying a pulse voltage for test ion deflection to the VMI photoelectronic modulation section to obtain accurate timing of the ion beam reaching the laser desorption region.

[0107] The above embodiments are only used to illustrate the present invention. The structure, connection method and manufacturing process of each component can be varied. All equivalent transformations and improvements made on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.

Claims

1. A 45° sampling anion photoelectron velocity imaging device, characterized in that, Includes a selective ion sampling and beam modulation module and a laser-induced photoelectron velocity imaging module; The selected ion sampling and beam modulation module includes a screen electrode plate, a base, and an ion beam modulation section. Several screen electrode plates are evenly spaced at 45° angles on the base. The top and bottom screen electrode plates are grounded, while the middle screen electrode plate is connected via a voltage divider resistor. An inlet for the ion beam modulation section is located on one side of the base. The screen electrode plates are used to select the target ions by mass and change their flight trajectory when a pulse voltage is applied. The ion beam modulation section is used to reduce the beam diameter, adjust the spatial position, and focus the target ions whose flight trajectories have been changed. The outlet of the ion beam modulation section is connected to the laser-induced photoelectron velocity imaging module. The laser-induced photoelectron velocity imaging module is used to perform laser-induced electron desorption onto the target ion pulse beam after quality selection and beam modulation to generate photoelectrons. Using the BASEX program, the photoelectron velocity distribution, photoelectron kinetic energy spectrum and electron binding energy spectrum of the target ion are obtained based on the photoelectron position distribution information.

2. The anion photoelectron velocity imaging device with 45° sampling as described in claim 1, characterized in that, The ion beam modulation section includes an ion beam modulation inlet lens, upper and lower deflection electrodes, a first grounded zero potential plate, left and right deflection electrodes, a second grounded zero potential plate, a first zero potential lens, a focusing lens, and a second zero potential lens. One side of the ion beam modulation inlet lens is connected to one side of the base, and the other side of the ion beam modulation inlet lens is connected to the laser-induced photoelectron velocity imaging module in sequence through the coaxial upper and lower deflection electrodes, the first ground zero potential plate, the left and right deflection electrodes, the second ground zero potential plate, the first zero potential lens, the focusing lens, and the second zero potential lens. The ion beam modulation inlet lens is used to eliminate stray ions with excessive incident angles, thereby reducing the beam diameter of the target ions. The upper and lower deflection electrodes and the left and right deflection electrodes are used to change the orientation of the target ion's flight direction in the vertical and horizontal directions by applying different DC voltages in the vertical and horizontal directions of the target ion's flight direction. The first and second grounded zero potential plates are used to block diverging ions. The first zero-potential lens, the focusing lens, and the second zero-potential lens are used to focus the target ions after adjusting their spatial position.

3. The anion photoelectron velocity imaging device with 45° sampling as described in claim 2, characterized in that, Both the first zero-potential lens and the second zero-potential lens are Einzel lenses.

4. The anion photoelectron velocity imaging device with 45° sampling as described in claim 2, characterized in that, The laser-induced photoelectron velocity imaging module includes a VMI photoelectron modulation section, a laser device, a magnetic / electric shielding cylinder, a rigid aluminum cylinder support, a fluorescent screen support, a CCD light-shielding cylinder, a CCD support plate, a grounded rigid aluminum cylinder, a photoelectron detector, a CCD camera, and a host computer. One side of the VMI photoelectronic modulation section is connected to the second zero-potential lens. The VMI photoelectronic modulation section is provided with an incident window for laser incidence of the laser device. The other side of the VMI photoelectronic modulation section extends into the grounded rigid aluminum cylinder. The VMI photoelectronic modulation section and the grounded rigid aluminum cylinder are fitted with the magnetic / electric shielding cylinder. The other side of the grounded rigid aluminum cylinder is connected to one side of the fluorescent screen support through a rigid aluminum cylinder bracket. The fluorescent screen support is provided with the photoelectronic detector. The other side of the fluorescent screen support is connected to the CCD support plate through the CCD light-shielding cylinder. The microchannel plate, the photoelectronic detector, and the CCD light-shielding cylinder are coaxially arranged. The CCD camera is provided on the CCD support plate. The CCD camera is also connected to the host computer. The laser device is used to emit a desorption laser through the incident window perpendicular to the direction of movement of the target ions, which intersects with the ion beam in the ionization region. The VMI photoelectronic modulation section is used to hit the target ion modulated by the ion beam modulation section with the desorption laser to generate photoelectrons of the target ion. The grounded rigid aluminum cylinder is used to ensure that desorbed electrons can fly freely in a vacuum without a field. The magnetic / electric shielding cylinder is used to shield external influences on spin electrons; The photoelectron detector is used to amplify the obtained photoelectron signal and convert it into a fluorescence signal; The CCD camera is used to capture fluorescence signals and record photoelectron position distribution information; The host computer is used to obtain the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion based on the photoelectron position distribution information using the BASEX program.

5. The anion photoelectron velocity imaging device with 45° sampling as described in claim 4, characterized in that, The VMI optoelectronic modulation section includes a sampling reference lens, a sampling beam collimating lens, a grid accelerating electrode plate, a first electrostatic lens plate, a second electrostatic lens plate, a third electrostatic lens plate, a fourth electrostatic lens plate, a fifth electrostatic lens plate, a sixth electrostatic lens plate, a seventh electrostatic lens plate, and an optoelectronic extraction plate arranged sequentially. Among them, every two adjacent plates of the first to seventh electrostatic lens plates are connected by an equal resistance, and an additional DC current is applied to the relevant plates. The target ions modulated by the ion beam modulation section enter through the sampling reference lens and are collimated by the sampling beam collimating lens. They are then struck by the desorption laser beam of the laser device at the midpoint between the grid accelerating electrode plate and the first electrostatic lens plate. The photoelectrons generated by photodesorption are accelerated and pushed towards the photoelectron detector through the second, third, fourth, fifth, sixth, and seventh electrostatic lens plates and the photoelectron extraction plate.

6. The anion photoelectron velocity imaging device with 45° sampling as described in claim 4, characterized in that, The photoelectron detector includes the microchannel plate and the photoelectron detection fluorescent screen; The microchannel plate is used to multiply the photoelectrons of the generated target ions through secondary electrons. The photoelectron detection fluorescent screen is used to convert the multiplied photoelectron signal into a fluorescent signal.

7. The anion photoelectron velocity imaging device with 45° sampling as described in claim 4, characterized in that, The laser-induced photoelectron velocity imaging module is arranged perpendicularly to or coaxially with the selective ion sampling and beam modulation module.

8. The anion photoelectron velocity imaging device with 45° sampling as described in claim 7, characterized in that, When the laser-induced photoelectron velocity imaging module is set perpendicularly to the mass-selected ion sampling and beam modulation module, the mass-selected ion sampling and beam modulation module is set on one side of the vertical laser-induced photoelectron velocity imaging module, corresponding to the position of the axis of the mass-selected ion sampling and beam modulation module. The ion beam, the desorption laser of the laser device, and the laser-induced photoelectron velocity imaging module are orthogonal to each other. A time-of-flight mass spectrometry (MCP) detector for determining the timing of the target ion and the desorption laser is set at the radial end of the ion beam.

9. A 45° sampling anion photoelectron velocity imaging method based on the 45° sampling anion photoelectron velocity imaging device according to any one of claims 1 to 8, characterized in that, include: Apply pulse voltage, and select the target ions by controlling the pulse timing mass selection ion sampling and beam modulation module. Use 45° sampling method to change the ion flight trajectory so that the target ions enter the beam modulation channel of the ion beam modulation section. The ion beam modulation section reduces the beam diameter, adjusts the spatial position, and focuses the target ions introduced into the beam modulation channel. The modulated target ions then fly to the laser-induced photoelectron velocity imaging module. The laser-induced photoelectron velocity imaging module uses a pulsed laser to induce electron desorption into the target ion pulse beam after quality selection and beam modulation, generating photoelectrons. Using the BASEX program, the module obtains the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion based on the photoelectron position distribution information.

10. The method as described in claim 9, characterized in that, The laser-induced photoelectron velocity imaging module uses a pulsed laser to induce electron desorption into the target ion pulsed beam after quality selection and beam modulation, generating photoelectrons. Using the BASEX program, based on the photoelectron position distribution information, it obtains the photoelectron velocity distribution, photoelectron kinetic energy spectrum, and electron binding energy spectrum of the target ion, including: The VMI optoelectronic modulation section aligns the quality-selected and beam-modulated target ions with the desorption laser emitted by the laser device in time and space. At the laser desorption point, the target ions interact with the linearly polarized beam to generate optoelectronics. The photoelectron detector amplifies the generated photoelectron signal, converts it into a fluorescence signal, records the photoelectron position distribution information, and transmits it to the host computer via optical fiber. The host computer uses the BASEX program to transform the photoelectron position distribution information through transpose, Abelian transformation and radial integration to obtain the required photoelectron velocity distribution, photoelectron kinetic energy spectrum and electron binding energy spectrum.

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