Photoelectron spectrometer

Abstract

The photoelectron spectrometer comprises a main cavity and a gas injection device, an inner cavity is defined by the main cavity, and the gas injection device is located outside the inner cavity, communicated with the inner cavity and used for injecting inert gas into the inner cavity; a vacuumizing hole is formed in the main cavity and is used for communicating the vacuumizing device with the inner cavity, so that the inner cavity is vacuumized through the vacuumizing device; eight electronic time-of-flight spectrometers are arranged in the inner cavity, and the electronic time-of-flight spectrometers are located on the same plane and arranged around a center shaft extending in the Y direction; the main cavity is provided with an incident port, and the incident port is used for enabling light to be incident into the inner cavity and transmitting the light along the central axis. To-be-detected light interacts with inert gas in the inner cavity to generate photoelectrons, and each electron time-of-flight spectrometer is used for collecting and detecting the photoelectrons; and an electronics system is arranged outside the inner cavity, is electrically connected with the electronic time-of-flight spectrometers, and is used for determining the photoelectron kinetic energy according to the detection results of the electronic time-of-flight spectrometers.

Description

Technical Field

[0001] The present invention relates to the field of photoelectron energy detection, and more specifically to a photoelectron spectrometer. Background Art

[0002] At present, the free electron laser (XFEL) devices in operation and construction in the world mainly include self-amplified spontaneous emission (SASE) (see references 1 and 2 for details) and high-gain high-order harmonic amplifier (HGHG) (see references 3 and 4 for details). The radiation characteristics of the XFEL beam line operating in the self-amplified spontaneous emission mode will fluctuate between pulses due to the random SASE process. This random characteristic causes the energy spectrum distribution of each XFEL pulse to have non-negligible fluctuations and random jitter. Typically, this pulse-to-pulse energy spectrum fluctuation can randomly vary within the range of 0.1% to 5% of the relative bandwidth (see reference 5 for details). Therefore, real-time and high-precision measurement of the XFEL energy spectrum has become an urgent problem to be solved in the field of scientific research. This not only plays a vital role in beam control, beam transmission control and experimental station debugging, but is also an indispensable basic beam information for scientific research users to analyze experimental data.

[0003] Among them, document 1 is: Kondratenko, A. M.; Saldin, E. L. Generating of coherent radiation by a relativistic electron beam in an ondulator. Part. Accel. 1980, 10, 207–216; document 2 is: Bonifacio, R.; Pellegrini, C.; Narducci, L. M. Collective instabilities and high-gain regime in a free electron laser. Opt. Commun. 1984, 50, 373–378; document 3 is: Yu, L.-H. Generation of intense uv radiation by subharmonically seeded single-pass free-electron lasers. Phys. Rev. A 1991, 44, 5178; document 4 is: Yu, L.-H.; Babzien, M. High-gain harmonic-generation free-electron laser. Science 2000, 289, 932–935; Document 5 is: Bermúdez Macias IJ, Düsterer S, Ivanov R, et al. Study of temporal, spectral, arrival time and energy fluctuations of SASE FEL pulses. Optics Express. 2021 Mar; 29(7): 10491-10508. Summary of the invention

[0004] The object of the present invention is to provide a photoelectron spectrometer for measuring the kinetic energy of photoelectrons in real time and with high precision so as to determine the energy spectrum information of light through the kinetic energy of photoelectrons.

[0005] Based on the above purpose, the present invention provides a photoelectron energy spectrometer, including a main cavity and a gas injection device, the main cavity defines an inner cavity, the gas injection device is located outside the inner cavity and communicated with the inner cavity, and is used to inject an inert gas into the inner cavity; a vacuum hole is provided on the main cavity, and the vacuum hole is used to connect the vacuum device with the inner cavity so as to evacuate the inner cavity through the vacuum device; eight electron flight time spectrometers are provided in the inner cavity, each of which is located in the same plane and is arranged around a central axis extending along the Y direction; an incident port is provided on the main cavity, and the incident port is used for allowing the light to be measured to be incident into the inner cavity and transmitted along the central axis; the light to be measured interacts with the inert gas in the inner cavity to generate photoelectrons, and each of the electron flight time spectrometers is used to collect and detect the photoelectrons; an electronic system is provided outside the inner cavity, and the electronic system is electrically connected to each electron flight time spectrometer, and is used to determine the kinetic energy of the photoelectrons according to the detection results of each electron flight time spectrometer.

[0006] Furthermore, each electron time-of-flight spectrometer is divided into four groups, and the two electron time-of-flight spectrometers in each group are symmetrically arranged with respect to the central axis and are coaxial, the two electron time-of-flight spectrometers in the first group are arranged in the Z direction, the two electron time-of-flight spectrometers in the second group are arranged in the X direction, the third group and the fourth group intersect with each other, and the angle between the axis of the two electron time-of-flight spectrometers in the third group and the X direction and the angle between the axis of the two electron time-of-flight spectrometers in the fourth group and the X direction are both 54.7°.

[0007] Furthermore, the distance between the two electron time-of-flight spectrometers in each group is 50 mm.

[0008] Furthermore, each electron time-of-flight spectrometer includes a shell, in which an electrostatic lens, a field-free drift tube and a detector are arranged in sequence. One end of the shell is formed as a receiving part, and the receiving part is used to allow the photoelectrons to enter the shell. The photoelectrons pass through the electrostatic lens and the field-free drift tube in sequence and then reach the detector. The detector is used to detect the number of photoelectrons arriving at the detector at different times.

[0009] Furthermore, the electronics system is used to determine the kinetic energy of the photoelectrons according to the number of photoelectrons arriving at the detectors at different times detected by the detectors of each electron flight time spectrometer.

[0010] Furthermore, the electrostatic lens comprises a plurality of non-magnetic annular electrodes which are arranged in sequence and at intervals, and a voltage is applied to each of the annular electrodes.

[0011] Furthermore, the distance between any two adjacent annular electrodes is the same; a hollow insulating column is arranged between any two adjacent annular electrodes and between the field-free drift tube and the annular electrode adjacent thereto.

[0012] Furthermore, the field-free drift tube is a non-magnetic metal cylindrical barrel; the length of the field-free drift tube is 550 mm.

[0013] Furthermore, the gas injection device includes a gas storage bottle, an air pipe and a capillary gas injection rod, the gas storage bottle is connected to one end of the air pipe, the other end of the air pipe is connected to one end of the capillary gas injection rod, and the other end of the capillary gas injection rod extends into the inner cavity; a micro-leakage valve is provided on the air pipe.

[0014] Furthermore, Permalloy is embedded on the inner wall of the main cavity and the inner wall of the outer shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of a photoelectron spectrometer according to an embodiment of the present invention;

[0016] Figure 2 is a schematic structural diagram of an electron time-of-flight spectrometer of a photoelectron spectrometer according to an embodiment of the present invention;

[0017] Figure 3 is a schematic structural diagram of a gas injection device of a photoelectron spectrometer according to an embodiment of the present invention;

[0018] Figure 4 A schematic diagram of the flight trajectory of photoelectrons in Simion simulation according to an embodiment of the present invention;

[0019] Figure 5 FIG. 4 is a schematic diagram of a time-of-flight spectrum of photoelectrons according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0021] like Figure 1As shown, an embodiment of the present invention provides a photoelectron spectrometer, including a main cavity 100 and a gas injection device 200, the main cavity 100 defines an inner cavity 110, the gas injection device 200 is located outside the inner cavity 110 and communicated with the inner cavity 110, and is used to inject an inert gas into the inner cavity 110; a vacuum hole 120 is provided on the main cavity 100, and the vacuum hole 120 is used to connect the vacuum device (such as a molecular pump) with the inner cavity 110, so as to evacuate the inner cavity 110 through the vacuum device, so that the inner cavity 110 is in a vacuum environment with a vacuum degree that meets the experimental requirements; eight electron flight time spectrometers 300 are provided in the inner cavity 110, and the eight electron flight time spectrometers 300 are located in the same plane (such as the XZ plane) and are arranged around the central axis O, wherein The central axis O extends along the Y direction, which is a direction perpendicular to the XZ plane (i.e., a direction perpendicular to the paper surface); an incident port (not shown in the figure) is provided on the main cavity 100, and the incident port is used for allowing the light to be measured (such as X-rays) to be incident into the inner cavity 110 and transmitted along the central axis O; after the light to be measured enters the inner cavity 110, it will interact with the inert gas, and the gas atoms absorb the high-energy light to be measured and are ionized to generate photoelectrons; each electron flight time spectrometer 300 is used to collect photoelectrons and detect the collected photoelectrons; an electronic system 400 is provided outside the inner cavity 110, and the electronic system 400 is connected to each electron flight time spectrometer 300 (for example, electrically connected) to determine the kinetic energy of the photoelectrons according to the detection results of each electron flight time spectrometer 300.

[0022] In some embodiments, the inert gas may be argon, krypton, xenon, nitrogen, or the like.

[0023] In some embodiments, eight electron time-of-flight spectrometers 300 are divided into four groups, each group includes two electron time-of-flight spectrometers 300, and the two electron time-of-flight spectrometers 300 in each group are symmetrically arranged relative to the central axis O and are coaxial (the axes of the two electron time-of-flight spectrometers pass through point O). The two electron time-of-flight spectrometers 300 in the first group are arranged in the Z direction, the two electron time-of-flight spectrometers 300 in the second group are arranged in the X direction, the third group and the fourth group intersect with each other, and the angle α between the axes of the two electron time-of-flight spectrometers 300 in the third group and the X direction is 54.7°, and the angle β between the axes of the two electron time-of-flight spectrometers 300 in the fourth group and the X direction is also 54.7°.

[0024] In some embodiments, the distance between the two electron time-of-flight spectrometers 300 in each group is 50 mm.

[0025] like Figure 2As shown, in some embodiments, the electron time-of-flight spectrometer 300 includes a housing 310, in which an electrostatic lens 320, a field-free drift tube 330 and a detector 340 are arranged. One end of the housing 310 is formed as a receiving part 311, and the receiving part 311, the electrostatic lens 320, the field-free drift tube 330 and the detector 340 are arranged in sequence. Photoelectrons can enter the housing 310 from the receiving part 311, and pass through the electrostatic lens 320 and the field-free drift tube 330 in sequence, and then reach the detector 340. The detector 340 can detect the number of photoelectrons arriving at the detector 340 at different times.

[0026] The electronics system is connected to the detector 340 of each electron flight time spectrometer 300, and is used to obtain the number of photoelectrons detected by the detector 340 and arriving at the detector 340 at different times and determine the kinetic energy of the photoelectrons based on them. Specifically, the electronics system can determine the photoelectron generation time based on the trigger device pre-arranged in the inner cavity 110, and then for each photoelectron arriving at the detector 300 at a certain moment, the time is subtracted from the photoelectron generation time to obtain the flight time of the photoelectron at that moment. The flight time spectrum of the photoelectron can be obtained based on the flight time of the photoelectron and the number of photoelectrons at different moments. The flight time of the photoelectron is related to the photoelectron energy, and the photoelectron kinetic energy can be obtained based on the flight time. The photoelectron kinetic energy is the difference between the photon energy and the electron binding energy. The electron binding energy can be obtained in advance based on the type of inert gas, thereby obtaining the photon energy, and the energy spectrum information of the light can be obtained based on the photon energy and the number of photoelectrons (the number of photoelectrons is proportional to the light intensity).

[0027] In some embodiments, the electrostatic lens 320 includes a plurality of non-magnetic metal annular electrodes 321 arranged in sequence and spaced apart from each other. A voltage is applied to the annular electrodes 321 to generate an electrostatic field. The electrostatic field generated by each annular electrode 321 can focus photoelectrons.

[0028] In some embodiments, the spacing between any two adjacent annular electrodes 321 can be set to be the same. A hollow insulating column is provided between any two adjacent annular electrodes 321 and between the field-free drift tube 330 and the adjacent annular electrode 321 for isolation. There can be multiple (for example, three) hollow insulating columns. Each annular electrode 321 is fixed by a screw passing through the central hole of the insulating column. A pin hole for fixing the lead is provided on the outer diameter edge of each annular electrode 321.

[0029] In some embodiments, the number of annular electrodes 321 is thirteen.

[0030] In some embodiments, the field-free drift tube 330 is a non-magnetic metal cylindrical barrel structure. The length of the field-free drift tube is 550 mm.

[0031] In some embodiments, the receiving portion 311 is formed in a cone shape, and its receiving angle is ±3° (ie, α=β=3°).

[0032] In some embodiments, the inner wall of the main cavity 100 and the inner wall of the outer shell 310 are both embedded with Permalloy as a magnetic shielding structure to reduce or eliminate the interference of the external magnetic field on the movement of electrons.

[0033] like Figure 3 As shown, in some embodiments, the gas injection device 200 may include a gas cylinder 210, a gas pipe 220 and a capillary gas injection rod 230. The gas cylinder 210 is used to store inert gas. The gas cylinder 210 is connected to one end of the gas pipe 220. The other end of the gas pipe 220 is connected to one end of the capillary gas injection rod 230. The other end of the capillary gas injection rod 230 extends into the inner cavity 110 to inject the inert gas in the gas cylinder 210 into the inner cavity 110. The gas pipe 220 may be provided with a micro-leakage valve 240, and the micro-leakage valve 240 may be used to control the on-off of the gas and the size of the gas flow.

[0034] The space enclosed by each electron time-of-flight spectrometer 300 may be referred to as a target area, and the capillary gas injection tube 230 may extend to the target area, thereby injecting the inert gas into the target area.

[0035] The gas injection direction is in the horizontal plane and forms a 45° angle with the optical path.

[0036] In some embodiments, the outer diameter of the capillary gas injection rod 230 is 1 mm, and the inner diameter of the capillary gas injection rod 230 is 0.3 mm.

[0037] The trajectory and flight time spectrum of the electron flight time spectrometer 300 were analyzed using Simion software. The results showed that under the conditions of a spot size of 3 mm and an initial electron kinetic energy of 120 electron volts, after being decelerated, focused and transmitted by the electron flight time spectrometer 300, the energy of the photoelectrons after deceleration was 10 eV before reaching the detector 340. Figure 4 This is the flight trajectory of electrons in Simion simulation. Figure 5 The time-of-flight spectra are those with initial kinetic energies of 120 eV (right peak) and 120.03 eV (left peak). The energy resolution of the electron time-of-flight spectrometer 300 reaches 0.03 eV, and the transmission efficiency of electrons is as high as 90%.

[0038] The photoelectron spectrometer of the embodiment of the present invention can measure the kinetic energy of photoelectrons in real time and with high precision, so as to determine the energy spectrum information of light (such as free electron laser) through the kinetic energy of photoelectrons, thereby providing strong technical support for in-depth research in the fields of energy spectrum diagnosis of free electron laser devices, optoelectronics, materials science, biomedicine, etc.

[0039] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A photoelectron spectrometer, characterized in that: The invention comprises a main cavity and a gas injection device, wherein the main cavity defines an inner cavity, the gas injection device is located outside the inner cavity and communicated with the inner cavity, and is used to inject an inert gas into the inner cavity; a vacuum hole is provided on the main cavity, and the vacuum hole is used to communicate the vacuum device with the inner cavity, so as to evacuate the inner cavity through the vacuum device; eight electron flight time spectrometers are provided in the inner cavity, and each electron flight time spectrometer is located in the same plane and is arranged around a central axis extending along the Y direction; an incident port is provided on the main cavity, and the incident port is used for allowing the light to be measured to be incident into the inner cavity and transmitted along the central axis; the light to be measured interacts with the inert gas in the inner cavity to generate photoelectrons, and each of the electron flight time spectrometers is used to collect and detect the photoelectrons; an electronic system is provided outside the inner cavity, and the electronic system is electrically connected to each electron flight time spectrometer, and is used to determine the kinetic energy of the photoelectrons according to the detection results of each electron flight time spectrometer.

2. The photoelectron spectrometer according to claim 1, characterized in that: Each electron time-of-flight spectrometer is divided into four groups, and the two electron time-of-flight spectrometers in each group are symmetrically arranged with respect to the central axis and are coaxial. The two electron time-of-flight spectrometers in the first group are arranged in the Z direction, the two electron time-of-flight spectrometers in the second group are arranged in the X direction, the third group and the fourth group intersect with each other, and the angle between the axis of the two electron time-of-flight spectrometers in the third group and the X direction and the angle between the axis of the two electron time-of-flight spectrometers in the fourth group and the X direction are both 54.7°.

3. The photoelectron spectrometer according to claim 2, characterized in that: The distance between the two electron time-of-flight spectrometers in each group is 50 mm.

4. The photoelectron spectrometer according to claim 1, characterized in that: Each electron time-of-flight spectrometer includes a shell, in which an electrostatic lens, a field-free drift tube and a detector are arranged in sequence. One end of the shell is formed as a receiving part, and the receiving part is used to allow the photoelectrons to enter the shell. The photoelectrons pass through the electrostatic lens and the field-free drift tube in sequence and then reach the detector. The detector is used to detect the number of photoelectrons reaching the detector at different times.

5. The photoelectron spectrometer according to claim 4, characterized in that: The electronics system is used to determine the kinetic energy of photoelectrons according to the number of photoelectrons arriving at the detectors at different times detected by the detectors of each electron flight time spectrometer.

6. The photoelectron spectrometer according to claim 4, characterized in that: The electrostatic lens comprises a plurality of non-magnetic annular electrodes which are arranged in sequence and at intervals, and a voltage is applied to each of the annular electrodes.

7. The photoelectron spectrometer according to claim 6, characterized in that: The distance between any two adjacent annular electrodes is the same; a hollow insulating column is arranged between any two adjacent annular electrodes and between the field-free drift tube and the annular electrode adjacent thereto.

8. The photoelectron spectrometer according to claim 4, characterized in that: The field-free drift tube is a non-magnetic metal cylindrical barrel; the length of the field-free drift tube is 550 mm.

9. The photoelectron spectrometer according to claim 1, characterized in that: The gas injection device includes a gas storage bottle, an air pipe and a capillary gas injection rod. The gas storage bottle is connected to one end of the air pipe, the other end of the air pipe is connected to one end of the capillary gas injection rod, and the other end of the capillary gas injection rod extends into the inner cavity; a micro-leakage valve is provided on the air pipe.

10. The photoelectron spectrometer according to claim 4, characterized in that: Permalloy is embedded on the inner wall of the main cavity and the inner wall of the shell.

Images