Beam combining device and method for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy

Abstract

The invention provides a beam combining device and method for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, and relates to the field of X-ray photoelectron spectroscopy experimental instruments. Comprising a vacuum cavity, the two ends of the vacuum cavity are externally connected with an X-ray free electron laser emitter and an experiment station terminal respectively, and the side wall of the vacuum cavity is externally connected with a pumping laser emitter, a vacuum pump set and a photoelectric detector. A beam combiner is arranged in an inner cavity of the vacuum cavity, and a beam combiner opening is formed in the beam combiner; the light path of the X-ray free electron laser passes through the hole of the beam combiner, and the light path of the pumping laser is reflected by the beam combiner and then is overlapped with the light path of the X-ray free electron laser to form a combined light beam.

Description

Technical Field

[0001] The invention relates to the field of X-ray photoelectron spectroscopy experimental instruments, in particular to a device and method for combining a pump laser and an X-ray free electron laser in an ultrafast X-ray photoelectron spectroscopy. Background Art

[0002] The interaction between X-rays and matter can excite photoelectrons. By detecting the energy and direction of the released photoelectrons, the electronic structure information of the occupied states and core energy levels with element resolution in different chemical environments can be obtained. This is the basic principle of X-ray photoelectron spectroscopy. X-ray free electron lasers can produce ultrashort and ultra-intense X-ray pulses with a pulse time length of the order of 10 fs. Using the properties of ultrashort pulses of X-ray free electron lasers, ultrafast X-ray photoelectron spectroscopy detection can be carried out. The experimental method is X-ray pump detection: generally, a laboratory laser is used to generate ultrashort laser pulses as pump light (energy is mainly in the infrared band) to pump the electrons in the sample to an excited state. By setting the delay time between the X-ray free electron laser and the pump laser, the X-ray free electron laser is used to detect the electron excitation and de-excitation processes in the material, and the non-equilibrium electronic structure of the material is studied.

[0003] The study of the non-equilibrium electronic structure of matter can detect materials in multiple dimensions and obtain relevant multi-dimensional information. In this research method, the choice of pump laser is relatively broad, and lasers of different wavelengths can be selected according to research needs. Commercial laboratory lasers can meet most needs, such as lasers with wavelengths of 1030, 800, 400 and 200nm. Currently, only X-ray free electron laser devices can provide lasers in the X-ray band, so ultrafast X-ray photoelectron spectroscopy research with femtosecond time resolution can only be carried out on this type of large scientific device. Therefore, a beam combining device for pump lasers and X-ray free electron lasers is a necessary condition for realizing the above experimental technology. Without a beam combining device, related research cannot be carried out.

[0004] In summary, there is a need for a device that can combine X-ray free electron laser and pump laser beams to carry out research on the non-equilibrium electronic structure of matter. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a beam combining device and method for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, which can realize the beam combining of pump laser and X-ray free electron laser, perform multi-dimensional detection of materials, and obtain relevant multi-dimensional information.

[0006] The present invention provides a beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, comprising a vacuum cavity, one end of the vacuum cavity is used to connect an X-ray free electron laser emitter, and the other end is used to connect an experimental station terminal, and the side wall of the vacuum cavity is used to connect a pump laser emitter, a vacuum pump group and a photodetector; the X-ray free electron laser emitter is suitable for emitting X-ray free electron laser; the pump laser emitter is suitable for emitting pump laser; the vacuum pump group is suitable for achieving an ultra-vacuum environment of the vacuum cavity; the experimental station terminal is suitable for loading samples and receiving the light spot of the combined beam; the photodetector is suitable for achieving time overlap of the combined beam; a beam combining mirror is provided in the inner cavity of the vacuum cavity, and a beam combining mirror opening is provided in the beam combining mirror; the light path of the X-ray free electron laser passes through the beam combining mirror opening, and the light path of the pump laser is reflected by the beam combining mirror and overlaps with the light path of the X-ray free electron laser to form a combined beam.

[0007] In a feasible implementation manner provided by the present invention, an X-ray free electron laser emitter interface and an experimental station terminal interface are respectively provided at both ends of the vacuum cavity, the X-ray free electron laser interface is externally connected to the X-ray free electron laser emitter through a flange, and the experimental station terminal interface is externally connected to the experimental station terminal through a flange; a pump laser emitter interface and a vacuum pump group interface are provided on the side wall of the vacuum cavity, the pump laser emitter interface is externally connected to the pump laser emitter through a flange, and the vacuum pump group interface is externally connected to the vacuum pump group through a flange.

[0008] A feasible implementation manner provided by the present invention further includes a beam combining mirror adjustment mechanism, which is arranged in the inner cavity of the vacuum chamber; the beam combining mirror adjustment mechanism includes a translation stage, a support stage and a fixed stage connected in sequence, and the beam combining mirror is arranged in the fixed stage.

[0009] In a feasible implementation manner provided by the present invention, an extended cavity extending along the radial direction of the vacuum cavity is further provided on the side wall of the vacuum cavity, and the inner cavity of the vacuum cavity is connected with the inner cavity of the extended cavity; the displacement stage is located in the inner cavity of the extended cavity.

[0010] In a feasible implementation manner provided by the present invention, two pump laser emitter interfaces are provided on the side wall of the vacuum cavity, and the two pump laser emitter interfaces are arranged sequentially along the axial direction of the vacuum cavity. Two extended cavities extending along the radial direction of the vacuum cavity are provided on the side wall of the vacuum cavity, and the two extended cavities are arranged sequentially along the axial direction of the vacuum cavity; the positions of the two pump laser emitter interfaces correspond one-to-one to the positions of the two extended cavities.

[0011] In a feasible implementation manner provided by the present invention, an observation window is further provided on the side wall of the extended cavity.

[0012] In a feasible implementation manner provided by the present invention, an electrode interface is further provided on the side wall of the extension cavity, and the electrode interface is suitable for switching electrode lines.

[0013] In a feasible implementation manner provided by the present invention, a photodetector interface is further provided on the side wall of the vacuum chamber; and a photodetector adjustment mechanism is also included, wherein the photodetector adjustment mechanism includes a three-dimensional adjustment platform and an adapter plate connected in sequence, wherein the photodetector is provided on the adapter plate, and the three-dimensional adjustment platform is suitable for moving the adapter plate to the optical path of the combined light beam; the three-dimensional adjustment platform is located outside the vacuum chamber and the end of the three-dimensional adjustment is connected to the photodetector interface, and the adapter plate and the photodetector are located in the inner cavity of the vacuum chamber through the photodetector interface.

[0014] In a feasible implementation manner provided by the present invention, the material of the vacuum chamber is stainless steel; and / or the vacuum degree of the vacuum chamber is 1×10 -8 Pa.

[0015] The present invention also provides a method for using a beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, which is characterized by comprising the following steps:

[0016] 1) Adjust the optical path of the X-ray free electron laser and the position of the beam combiner so that the optical path of the X-ray free electron laser can pass through the opening of the beam combiner, and then adjust the optical path of the pump laser so that the pump laser is emitted toward the mirror surface of the beam combiner and the light spot can cover the opening of the beam combiner, and the pump laser is reflected by the mirror surface of the beam combiner;

[0017] 2) A combined beam is formed between the X-ray free electron laser that passes through the opening of the beam combiner and the pump laser that is reflected by the beam combiner, and the spot of the combined beam hits the sample at the terminal of the experimental station.

[0018] The present invention provides a beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, which has the following beneficial effects:

[0019] The present invention can realize the beam combination of pump laser and X-ray free electron laser, and can perform multi-dimensional detection of materials to obtain relevant multi-dimensional information, including real-space high-resolution imaging of materials, momentum-space electronic structure information, momentum-space electron spin information and ultrafast electron dynamics processes, and ultrafast electron dynamics photoelectron energy spectrum testing. It can be used to measure the electronic structure (including electron spin) and dynamics processes of quantum materials and functional materials (such as semiconductor materials and energy materials), and can also be used to study the mechanism of solid chemical reactions and catalytic processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1It is a side view of the present invention.

[0021] Figure 2 It is a front view of the present invention.

[0022] Figure 3 It is a structural schematic diagram of the beam combiner in the present invention.

[0023] Figure 4 It is a schematic diagram of the structure of the beam combiner adjustment mechanism and the beam combiner in the present invention.

[0024] Figure 5 It is a structural schematic diagram of the photoelectric detector and the photoelectric detector adjustment mechanism in the present invention.

[0025] Reference numerals

[0026] Vacuum chamber 1

[0027] X-ray free electron laser emitter interface 11

[0028] Experimental station terminal interface 12

[0029] Pump laser transmitter interface 13

[0030] Vacuum pump group interface 14

[0031] Photodetector interface 15

[0032] Beam combiner 2

[0033] Beam combiner opening 21

[0034] Beam combiner adjustment mechanism 3

[0035] Translation stage 31

[0036] Support table 32

[0037] Fixed table 33

[0038] Extended cavity 4

[0039] Observation window 41

[0040] Electrode interface 42

[0041] Photoelectric detector adjustment mechanism 5

[0042] Three-dimensional adjustment table 51

[0043] Adapter plate 52 DETAILED DESCRIPTION

[0044] 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.

[0045] 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.

[0046] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0047] The present invention provides a beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, referring to Figure 1 and Figure 2 , comprising a vacuum chamber 1, one end of which is used to connect to an X-ray free electron laser emitter, and the other end is used to connect to an experimental station terminal, and the side wall of the vacuum chamber 1 is used to connect to a pump laser emitter, a vacuum pump group and a photodetector. In a specific embodiment, the inner cavity environment of the vacuum chamber 1 is an ultra-vacuum environment, and the vacuum degree is ≤1×10 -8 Pa, and the material of the vacuum chamber 1 is stainless steel. As an illustration, the X-ray free electron laser emitter is suitable for emitting X-ray free electron laser; the pump laser emitter is suitable for emitting pump laser; the vacuum pump group is suitable for achieving an ultra-vacuum environment of the vacuum chamber 1; the experimental station terminal is suitable for loading samples and receiving the light spot of the combined beam; the photodetector is suitable for achieving the time overlap of the combined beam. Figure 1 and Figure 3The inner cavity of the vacuum chamber 1 is provided with a beam combiner 2, and the beam combiner 2 is provided with a beam combiner opening 21. The beam combiner 2 has only one side that can reflect the pump laser, and this side is called the mirror surface of the beam combiner 2. The description of "reflected by the beam combiner 2" in the following text is expressed as "reflected by the mirror surface of the beam combiner 2". The optical path of the X-ray free electron laser passes through the beam combiner opening 21. After being reflected by the beam combiner 2, the optical path of the pump laser overlaps with the optical path of the X-ray free electron laser and forms a combined beam. As a supplementary explanation, the optical path of the X-ray free electron laser is a straight line. Figure 1 The direction of the middle arrow indicates the direction of the free electron laser. This straight line usually coincides with the central axis of the vacuum chamber 1. The optical path of the pump laser is a broken line, and the broken angle is usually a right angle. Figure 2 The direction of the middle arrow indicates the direction of the pump laser before it is reflected by the beam combiner 2. The pump laser first irradiates the beam combiner 2 and covers the beam combiner opening 21. Then the pump laser is reflected by the beam combiner 2. The optical path of the reflected pump laser overlaps with the optical path of the X-ray free electron laser to form a combined beam. Generally speaking, the optical path of the pump laser before being reflected by the beam combiner 2 is on the same horizontal plane as the optical path of the X-ray free electron laser but is perpendicular to each other. The positional relationship between the pump laser and the X-ray free electron laser can be referred to. Figure 1 and Figure 2 Arrows in . As a supplementary explanation, regarding the beam combiner 2: the beam combiner opening 21 is usually cut obliquely to ensure that the X-ray free electron laser can pass through the beam combiner opening 21 when the beam combiner 2 is tilted. The spot size of the X-ray free electron laser is very small (generally several to tens of microns), so the diameter of the beam combiner opening 21 is 1 to 2 mm to meet the X-ray free electron laser passing through, and the pump laser spot size is larger (generally several millimeters), so the reflection of the pump laser is not affected under the opening size of 1 to 2 mm. The present invention can realize the beam combination of the pump laser and the X-ray free electron laser, perform multi-dimensional detection of materials, and obtain relevant multi-dimensional information, including real-space high-resolution imaging of materials, momentum-space electronic structure information, momentum-space electron spin information and ultrafast electron dynamics process, ultrafast electron dynamics photoelectron spectrum test, which can be used to measure the electronic structure (including electron spin) and dynamics process of quantum materials and functional materials (such as semiconductor materials, energy materials), and can also be used for mechanism research of solid chemical reactions and catalytic processes.

[0048] In the beam combining device of the pump laser and the X-ray free electron laser provided by the present invention, refer to Figure 1, an X-ray free electron laser emitter interface 11 and an experimental station terminal interface 12 are respectively provided at both ends of the vacuum chamber 1, wherein the X-ray free electron laser emitter interface 11 is externally connected to the X-ray free electron laser emitter through a flange, and the experimental station terminal interface 12 is externally connected to the experimental station terminal through a flange; a pump laser emitter interface 13 and a vacuum pump group interface 14 are provided on the side wall of the vacuum chamber 1, wherein the pump laser emitter interface 13 is externally connected to the pump laser emitter through a flange, and the vacuum pump group interface 14 is externally connected to the vacuum pump group through a flange. As an illustration, the X-ray free electron laser emitter interface 11, the experimental station terminal interface 12, the pump laser emitter interface 13 and the vacuum pump group interface 14 are all standard CF flange interfaces. As an example, the X-ray free electron laser emitter may be the Shanghai soft X-ray free electron laser device, the experimental station terminal may be an ultrafast physics experimental station or an ultrafast chemistry experimental station, and the pump laser emitter may be the Legend Elite Duo HE + , the vacuum pump set can be nEXT240 CF100.

[0049] In the beam combining device of the pump laser and the X-ray free electron laser provided by the present invention, refer to Figure 1 and Figure 4 , and also includes a beam combining mirror adjustment mechanism 3, which is arranged in the inner cavity of the vacuum chamber 1; the beam combining mirror adjustment mechanism 3 includes a displacement stage 31, a support stage 32 and a fixing stage 33 connected in sequence, and the beam combining mirror 2 is arranged in the fixing stage 33. As a supplementary explanation, regarding the fixing stage 33: refer to Figure 4 The fixed platform 33 can clamp and fix the beam combiner 2, and the fixed platform 33 includes two piezoelectric ceramic motors compatible with ultra-high vacuum. The movement of the two piezoelectric ceramic motors can control the pitch angle of the beam combiner 2, thereby changing the optical path of the pump laser, achieving the overlap of the reflected optical path of the pump laser and the X-ray free electron laser, and converging the light spots of the two to the sample point. The model of the fixed platform 33 can be Newport-8822-UHV. About the support platform 32: See Figure 4 The support platform 32 is made of stainless steel. Generally speaking, the support platform 32 is connected to the fixed platform 33 and the displacement platform 31 by means of threaded holes and bolts. Figure 4The translation stage 31 includes two ultra-high vacuum mechanical motors for controlling the movement in the horizontal and vertical directions. The horizontal and vertical directions mentioned here are relative to the plane where the optical path of the X-ray free electron laser or the optical path of the combined beam is located. The accuracy of the two ultra-high vacuum mechanical motors is ≤1μm. By moving the translation stage 31 in the horizontal and vertical directions, the beam combining mirror opening 21 can be moved to the optical path of the X-ray free electron laser, so that the X-ray free electron laser can pass through the beam combining mirror opening 21 smoothly, ensuring the beam combining of the X-ray free electron laser and the pump laser. The model of the translation stage 31 can be VSM17-XZ-050-LS.

[0050] In the beam combining device of the pump laser and the X-ray free electron laser provided by the present invention, refer to Figure 1 , the side wall of the vacuum cavity 1 is also provided with an extended cavity 4 extending along the radial direction of the vacuum cavity 1, and the inner cavity of the vacuum cavity 1 is connected with the inner cavity of the extended cavity 4; the displacement stage 31 is located in the inner cavity of the extended cavity 4. As an illustration, the end of the extended cavity 4 is usually closed with a flange, and the displacement stage 31 is usually arranged on the flange used to close the end of the extended cavity 4. With reference to the optical path of the X-ray free electron laser, the position of the extended cavity 4 should be slightly behind the pump laser emitter interface 13. If the position of the extended cavity 4 is ahead of the pump laser emitter interface 13, the pump laser cannot hit the beam combiner 2.

[0051] In the beam combining device of the pump laser and the X-ray free electron laser provided by the present invention, refer to Figure 1 , two pump laser emitter interfaces 13 are provided on the side wall of the vacuum cavity 1, and the two pump laser emitter interfaces 13 are sequentially arranged along the axial direction of the vacuum cavity 1; two extended cavities 4 extending along the radial direction of the vacuum cavity 1 are provided on the side wall of the vacuum cavity 1, and the two extended cavities 4 are sequentially arranged along the axial direction of the vacuum cavity 1; the positions of the two pump laser emitter interfaces 13 correspond to the positions of the two extended cavities 4. As an illustration, in the process of using the present invention, usually only one set of corresponding pump laser emitter interfaces 13 and extended cavities 4 is used, and the extra set of pump laser emitter interfaces 13 and one extended cavity 4 are used as backup.

[0052] In the beam combining device of the pump laser and the X-ray free electron laser provided by the present invention, refer to Figure 1 An observation window 41 is also provided on the side wall of the extended cavity 4 , and the observation window 41 is used to observe the current state of the beam combiner adjustment mechanism 3 .

[0053] In the beam combining device of the pump laser and the X-ray free electron laser provided by the present invention, refer to Figure 1An electrode interface 42 is also provided on the side wall of the extended cavity 4 , and the electrode interface 42 is suitable for switching electrode lines. The electrode lines are usually connected to the beam combiner adjustment mechanism 3 to supply power to the beam combiner adjustment mechanism 3 .

[0054] In the beam combining device of the pump laser and the X-ray free electron laser provided by the present invention, refer to Figure 1 and Figure 5 , a photodetector interface 15 is also provided on the side wall of the vacuum chamber 1; it also includes a photodetector adjustment mechanism 5, the photodetector adjustment mechanism 5 includes a three-dimensional adjustment platform 51 and an adapter plate 52 connected in sequence, the photodetector is arranged on the adapter plate 52, the three-dimensional adjustment platform 51 is suitable for moving the adapter plate 52 to the optical path of the combined light beam; the three-dimensional adjustment platform 51 is located outside the vacuum chamber 1 and the end of the three-dimensional adjustment platform 51 is connected to the photodetector interface 15, the adapter plate 52 and the photodetector are located in the inner cavity of the vacuum chamber 1 through the photodetector interface 15. About the photodetector: The function of the photodetector is to convert the optical signal into an electrical signal, and the response time is in the order of picoseconds. With the help of photoelectric signal reading, the time window of the pump laser and the X-ray free electron laser can be compressed to the order of tens of picoseconds. In addition to spatial overlap, time overlap is also achieved. The model of the photodetector can be UPD-35-UVIR-P. About the three-dimensional adjustment table 51: The three-dimensional adjustment table 51 can realize the motion control of the photodetector in the three directions of xyz, so that the combined beam formed by the pump laser and the X-ray free electron laser can hit the probe of the photodetector and generate a photoelectric signal. The model of the three-dimensional adjustment table 51 can be XYZ-CF63-35. As an illustration, the photodetector is not always in the optical path of the combined beam. When the pump laser and the X-ray free electron laser complete spatial overlap, the photodetector is moved to the optical path of the combined beam through the three-dimensional adjustment table 51 to achieve the time overlap of the combined beam. When the time overlap is completed, the photodetector is moved out of the optical path of the combined beam again through the three-dimensional adjustment table 51 so that the combined beam can hit the sample at the terminal of the experimental station.

[0055] The embodiment of the present invention further provides a method for using a beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, comprising the following steps:

[0056] 1) Adjust the optical path of the X-ray free electron laser and the position of the beam combiner 2 so that the optical path of the X-ray free electron laser can pass through the beam combiner opening 21, and then adjust the optical path of the pump laser so that the pump laser is emitted toward the mirror surface of the beam combiner 2 and the light spot can cover the beam combiner opening 21, and the pump laser is reflected by the mirror surface of the beam combiner 2;.

[0057] 2) The X-ray free electron laser that passes through the beam-combining mirror opening 21 and the pump laser that is reflected by the beam-combining mirror 2 form a combined light beam, and the light spot of the combined light beam hits the sample at the terminal of the experimental station; further, the photodetector is moved into the light path of the combined light beam through the photodetector adjustment mechanism 5 to achieve time overlap of the combined light beam, and then the photodetector is moved out of the light path of the combined light beam through the photodetector, so that the light spot of the combined light beam hits the sample at the terminal of the experimental station.

[0058] 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 beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy, characterized in that: It comprises a vacuum chamber (1), one end of the vacuum chamber (1) is used to connect to an X-ray free electron laser emitter, and the other end is used to connect to an experimental station terminal, and the side wall of the vacuum chamber (1) is used to connect to a pump laser emitter, a vacuum pump group and a photoelectric detector; The X-ray free electron laser emitter is suitable for emitting X-ray free electron laser; The pump laser emitter is suitable for emitting pump laser; The vacuum pump assembly is suitable for achieving an ultra-vacuum environment in the vacuum chamber (1); The experimental station terminal is suitable for loading samples and receiving the light spot of the combined light beam; The photoelectric detector is suitable for achieving the time coincidence of the combined light beams; A beam combining mirror (2) is provided in the inner cavity of the vacuum cavity (1), and a beam combining mirror opening (21) is provided in the beam combining mirror (2); the optical path of the X-ray free electron laser passes through the beam combining mirror opening (21), and the optical path of the pump laser is reflected by the beam combining mirror (2) and overlaps with the optical path of the X-ray free electron laser to form a combined beam.

2. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 1, characterized in that: An X-ray free electron laser emitter interface (11) and an experimental station terminal interface (12) are respectively provided at two ends of the vacuum chamber (1), wherein the X-ray free electron laser emitter interface (11) is externally connected to the X-ray free electron laser emitter via a flange, and the experimental station terminal interface (12) is externally connected to the experimental station terminal via a flange; A pump laser emitter interface (13) and a vacuum pump group interface (14) are provided on the side wall of the vacuum cavity (1); the pump laser emitter interface (13) is externally connected to the pump laser emitter via a flange, and the vacuum pump group interface (14) is externally connected to the vacuum pump group via a flange.

3. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 2, characterized in that: It also comprises a beam combining mirror adjustment mechanism (3), which is arranged in the inner cavity of the vacuum chamber (1); the beam combining mirror adjustment mechanism (3) comprises a displacement platform (31), a support platform (32) and a fixing platform (33) which are connected in sequence, and the beam combining mirror (2) is arranged in the fixing platform (33).

4. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 3, characterized in that: An extended cavity (4) extending in the radial direction of the vacuum cavity (1) is also provided on the side wall of the vacuum cavity (1); the inner cavity of the vacuum cavity (1) is connected to the inner cavity of the extended cavity (4); and the displacement stage (31) is located in the inner cavity of the extended cavity (4).

5. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 4, characterized in that: Two pump laser emitter interfaces (13) are provided on the side wall of the vacuum cavity (1), and the two pump laser emitter interfaces (13) are arranged in sequence along the axial direction of the vacuum cavity (1); two extended cavities (4) extending in the radial direction of the vacuum cavity (1) are provided on the side wall of the vacuum cavity (1), and the two extended cavities (4) are arranged in sequence along the axial direction of the vacuum cavity (1); the positions of the two pump laser emitter interfaces (13) correspond one-to-one to the positions of the two extended cavities (4).

6. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 4 or 5, characterized in that: An observation window (41) is also provided on the side wall of the extended cavity (4).

7. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 4 or 5, characterized in that: An electrode interface (42) is also provided on the side wall of the extended cavity (4), and the electrode interface (42) is suitable for switching electrode lines.

8. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 1, characterized in that: The vacuum chamber (1) is also provided with a photodetector interface (15) on the side wall thereof; and further comprises a photodetector adjustment mechanism (5), wherein the photodetector adjustment mechanism (5) comprises a three-dimensional adjustment platform (51) and an adapter plate (52) connected in sequence, wherein the photodetector is arranged on the adapter plate (52), and the three-dimensional adjustment platform (51) is suitable for moving the adapter plate (52) to the optical path of the combined light beam; The three-dimensional adjustment platform (51) is located outside the vacuum chamber (1) and an end of the three-dimensional adjustment platform (51) is connected to a photodetector interface (15); the adapter plate (52) and the photodetector pass through the photodetector interface (15) and are located in the inner cavity of the vacuum chamber (1).

9. The beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to claim 1, characterized in that: The material of the vacuum chamber (1) is stainless steel; and / or the vacuum degree of the vacuum chamber (1) is 1×10 -8 Pa.

10. A method for using the beam combining device for pump laser and X-ray free electron laser in ultrafast X-ray photoelectron spectroscopy according to any one of claims 1 to 9, characterized in that: The steps include: 1) adjusting the optical path of the X-ray free electron laser and the position of the beam combiner (2) so that the optical path of the X-ray free electron laser can pass through the beam combiner opening (21), and then adjusting the optical path of the pump laser so that the pump laser is emitted toward the mirror surface of the beam combiner (2) and the light spot can cover the beam combiner opening (21), and at the same time, the pump laser is reflected by the mirror surface of the beam combiner (2); 2) The X-ray free electron laser passing through the beam combining mirror opening (21) and the pump laser reflected by the beam combining mirror (2) form a combined beam, and the spot of the combined beam is projected onto the sample at the terminal of the experimental station.

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