X-ray absorption spectrum acquisition device and method

Abstract

The invention relates to an X-ray absorption spectrum collecting device and method.The device comprises an undulator, a monochromator, an X-ray absorption element, a sample table, a first current amplifier, a first volt-frequency converter, a second current amplifier, a second volt-frequency converter, a collector and an upper computer; the first current amplifier is connected with the X-ray absorption element, the first volt-frequency converter is connected with the first current amplifier, the second current amplifier is connected with the sample, the second volt-frequency converter is connected with the second current amplifier, and the second current amplifier is connected with the X-ray absorption element. The collector is respectively connected with the first volt-frequency converter and the second volt-frequency converter, and the upper computer is connected with the collector. According to the X-ray absorption spectrum acquisition device and method, the reference light stability can be improved, and the influence of reference luminous flux oscillation on an X-ray absorption spectrum result is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray absorption spectrum acquisition, and more specifically to an X-ray absorption spectrum acquisition device and method. Background Art

[0002] After X-rays pass through a sample, their intensity attenuates and the degree of attenuation is closely related to the structure and composition of the sample. This study of the relationship between the transmission intensity and the incident X-ray intensity is called X-ray absorption spectroscopy. X-ray absorption spectroscopy is a powerful means of material characterization. It includes X-ray absorption near-edge structure and extended X-ray absorption fine structure. X-ray absorption spectroscopy is a technique for studying the relationship between the intensity attenuation of X-rays after they pass through a sample and the structure and composition of the sample. This attenuation is related to the absorption and scattering of X-rays by the sample, in which the absorption effect is much greater than the scattering effect. Synchrotron radiation X-ray absorption spectroscopy includes two detection modes: total electron yield mode (TEY) and total fluorescence yield (TFY), which are used to detect the electronic structure information of the surface interface and bulk elements of the material, respectively. The TEY mode obtains X-ray absorption spectrum data by measuring the total amount of photoelectrons generated by X-ray excitation on the sample surface. In this mode, electrons on the surface or near-surface area of ​​the sample are excited and escape, so the TEY mode is very sensitive to the surface of the sample. The TFY mode obtains X-ray absorption spectrum data by measuring the fluorescence signal emitted by the sample due to X-ray excitation. In this mode, the information of the sample bulk phase is detected because the fluorescence signal can penetrate deeper areas of the sample. The undulator light source is a key component used in synchrotron radiation sources and free electron lasers. It is a periodic magnetic structure composed of a series of dipole magnets, which can be permanent magnets or superconducting magnets. When a high-energy electron beam passes through the undulator, it oscillates under the action of a periodic magnetic field, thereby emitting light radiation. For an undulator light source, GAP refers to the distance between the magnets. At each energy point, the GAP value at which the undulator can output the maximum light intensity is different. When doing spectroscopy experiments, in order to maintain the maximum light flux, the GAP value of each energy point is different, so when reaching a new energy point, the size of the GAP needs to be adjusted, which is GAP joint modulation.

[0003] In X-ray absorption spectrum experiments, the reference light signal and sample signal are usually normalized to obtain the final X-ray absorption spectrum. In X-ray absorption spectrum experiments, GAP joint adjustment will cause reference light flux jitter, which will affect the measurement accuracy and repeatability of X-ray absorption spectrum. The absorption spectrum signal of trace elements is weak, and the signal-to-noise ratio of the absorption spectrum is easily affected by the jitter of the reference light flux. When characterizing and measuring some weak signals, it will affect the experimenter's judgment of the results. Summary of the invention

[0004] The object of the present invention is to provide an X-ray absorption spectrum acquisition device and method to improve the stability of reference light and reduce the influence of reference light flux oscillation on X-ray absorption spectrum results.

[0005] Based on the above purpose, the present invention provides an X-ray absorption spectrum acquisition device on one hand, including an undulator, a monochromator, an X-ray absorption element, a sample stage, a first current amplifier, a first volt-frequency converter, a second current amplifier, a second volt-frequency converter, a collector and a host computer, wherein the sample stage is used to place a sample, the first current amplifier is connected to the X-ray absorption element, the first volt-frequency converter is connected to the first current amplifier, the second current amplifier is connected to the sample, the second volt-frequency converter is connected to the second current amplifier, the collector is connected to the first volt-frequency converter and the second volt-frequency converter respectively, and the host computer is connected to the collector; the undulator is used to emit X-rays, the monochromator is used to receive the X-rays and adjust the energy of the X-rays so that X-rays of different energies pass through the X-rays in sequence. The X-ray absorption element and the sample, the X-ray absorption element is used to generate a first photocurrent signal after being irradiated with X-rays, the first current amplifier is used to amplify the first photocurrent signal into a first voltage signal, and the first volt-frequency converter is used to convert the first voltage signal into a first frequency signal; the sample generates a second photocurrent signal after being irradiated with X-rays, the second current amplifier is used to amplify the second photocurrent signal into a second voltage signal, and the second volt-frequency converter is used to convert the second voltage signal into a second frequency signal; the collector is configured to collect the first frequency signal to obtain first collection data, and to collect the second frequency signal to obtain second collection data; the host computer is configured to determine the X-ray absorption spectrum of the sample based on the first collection data and the second collection data.

[0006] Furthermore, the first frequency signal and the second frequency signal are both continuous rectangular pulse signals.

[0007] Furthermore, the collector includes an FMC to double-row pin module, an FPGA board and a switch, wherein the FMC to double-row pin module is used to convert the first frequency signal and the second frequency signal into digital signals of 0 and 1, and transmit the digital signals to the FPGA board; the FPGA board is used to collect the digital signals of the first frequency signal and the second frequency signal to obtain the first collected data and the second collected data, and transmit the first collected data and the second collected data to the host computer through the switch.

[0008] Furthermore, it also includes a controller, the host computer is connected to the controller, and the controller is respectively connected to the undulator and the monochromator, and is used to control the magnet spacing of the undulator and the energy of the X-rays emitted from the monochromator according to the control instructions sent by the host computer.

[0009] Furthermore, when the controller makes the X-rays emitted from the monochromator have each energy, the controller simultaneously makes the magnet spacing of the undulator become the optimal value corresponding to the X-rays of the energy.

[0010] Furthermore, the collector is specifically configured as follows: For each energy of X-ray, the first frequency signal is accumulated multiple times by pulse signal accumulation within the preset external acquisition time to obtain multiple first accumulated values ​​as the first acquisition data; and the second frequency signal is accumulated multiple times by pulse signal accumulation to obtain multiple second accumulated values ​​as the second acquisition data; wherein the time for each pulse signal accumulation is the preset internal acquisition time.

[0011] Furthermore, the host computer is specifically configured as follows: For each energy of X-ray, the first accumulated values ​​under the energy of X-ray are summed and averaged to obtain a first accumulated total value and a first accumulated average value under the energy of X-ray; and the second accumulated values ​​under the energy of X-ray are summed and averaged to obtain a second accumulated total value and a second accumulated average value under the energy of X-ray; Obtaining a minimum value among the first cumulative total values ​​under each energy of the X-ray and a minimum value among the second cumulative total values ​​under each energy of the X-ray, as the minimum first cumulative total value and the minimum second cumulative total value, respectively; For each energy of X-rays, the number of first cumulative values ​​of the X-rays under the energy to be eliminated is determined according to the first cumulative total value and the first cumulative average value of the X-rays under the energy and the minimum first cumulative total value; and the number of second cumulative values ​​of the X-rays under the energy to be eliminated is determined according to the second cumulative total value and the second cumulative average value of the X-rays under the energy and the minimum second cumulative total value; For each energy of X-ray, first cumulative values ​​of X-rays under the energy are eliminated according to the first cumulative elimination number of X-rays under the energy, so as to obtain first cumulative values ​​after elimination of X-rays under the energy; and second cumulative values ​​of X-rays under the energy are eliminated according to the second cumulative elimination number of X-rays under the energy, so as to obtain second cumulative values ​​after elimination of X-rays under the energy; For each energy of X-ray, sum the first cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized first cumulative total value under the X-ray of the energy; and sum the second cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized second cumulative total value under the X-ray of the energy; For each energy of X-ray, the absorption coefficient of the X-ray under the energy is determined according to the optimized first cumulative total value and the optimized second cumulative total value under the X-ray of the energy.

[0012] Another aspect of the present invention provides an X-ray absorption spectrum acquisition method, which comprises: Provide an X-ray absorption spectrum collection device as described above; The undulator emits X-rays, and the energy of the X-rays emitted from the monochromator and the magnet spacing of the undulator are adjusted by the host computer, and under each energy of the X-rays, the magnet spacing of the undulator is the optimal value corresponding to the energy; Under each energy of X-ray, the first current amplifier amplifies the first photocurrent signal generated by the X-ray absorption element into a first voltage signal, the first volt-frequency converter converts the first voltage signal into a first frequency signal, the second current amplifier amplifies the second photocurrent signal generated by the sample into a second voltage signal, and the second volt-frequency converter converts the second voltage signal into a second frequency signal; Under each energy of X-ray, the collector collects the first frequency signal under the energy of X-ray to obtain first collected data; and collects the second frequency signal under the energy of X-ray to obtain second collected data; The host computer determines the X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data under the X-rays of various energies.

[0013] Further, under each energy of X-ray, the collector collects a first frequency signal under the energy of X-ray to obtain first collected data; and collects a second frequency signal under the energy of X-ray to obtain second collected data, specifically including: Under each energy of X-ray, according to the external acquisition time and the built-in acquisition time sent in advance to the collector by the host computer, the collector accumulates the pulse signals of the first frequency signal multiple times within the external acquisition time to obtain multiple first accumulated values ​​as the first acquisition data; and accumulates the pulse signals of the second frequency signal multiple times to obtain multiple second accumulated values ​​as the second acquisition data; wherein the time for each pulse signal accumulation is the built-in acquisition time.

[0014] Further, determining the X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data under the X-ray of each energy specifically includes: For each energy of the X-ray, summing and averaging the first accumulated values ​​of the X-ray of the energy to obtain a first accumulated total value and a first accumulated average value of the X-ray of the energy; Obtaining a minimum value among the first cumulative total values ​​under the X-ray of each energy as a minimum first cumulative total value; Obtaining a minimum value among the second cumulative total values ​​under the X-rays of each energy as a minimum second cumulative total value; For each energy of X-ray, the number of first cumulative values ​​of the X-ray under the energy to be eliminated is determined according to the first cumulative total value, the first cumulative average value and the minimum first cumulative total value of the X-ray under the energy; and the number of second cumulative values ​​of the X-ray under the energy to be eliminated is determined according to the second cumulative total value, the second cumulative average value and the minimum second cumulative total value of the X-ray under the energy; For each energy of X-ray, first cumulative values ​​of X-rays under the energy are eliminated according to the first cumulative elimination number of X-rays under the energy, so as to obtain first cumulative values ​​after elimination of X-rays under the energy; and second cumulative values ​​of X-rays under the energy are eliminated according to the second cumulative elimination number of X-rays under the energy, so as to obtain second cumulative values ​​after elimination of X-rays under the energy; For each energy of X-ray, sum the first cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized first cumulative total value under the X-ray of the energy; and sum the second cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized second cumulative total value under the X-ray of the energy; For each energy of X-ray, the absorption coefficient of the X-ray under the energy is determined according to the optimized first cumulative total value and the optimized second cumulative total value under the X-ray of the energy.

[0015] In the X-ray absorption spectrum acquisition device and method of the present invention, the collector synchronously acquires multiple first cumulative values ​​and multiple second cumulative values ​​under each energy of X-ray, and by deleting a specified number of values ​​among the multiple first cumulative values ​​and the multiple second cumulative values, a more stable light intensity can be obtained, the intensity stability of the reference light at different energy points is improved, and the signal synchronization of the X-ray absorption element and the sample is maintained, thereby reducing the influence of the reference light flux oscillation on the X-ray absorption spectrum result, and obtaining a more accurate X-ray absorption spectrum. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of an X-ray absorption spectrum acquisition device according to an embodiment of the present invention; Figure 2 is a structural block diagram of a collector of an X-ray absorption spectrum collection device according to an embodiment of the present invention; Figure 3is a flow chart of a method for collecting X-ray absorption spectra according to an embodiment of the present invention; Figure 4 The figure is a comparison diagram of the Fe element absorption spectrum obtained by using the device and method of the present invention and the Fe element absorption spectrum obtained by using the existing method. DETAILED DESCRIPTION

[0017] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0018] like Figure 1As shown, an embodiment of the present invention provides an X-ray absorption spectrum acquisition device, including an undulator 100, a monochromator 200, an X-ray absorption element 300, a sample stage 400, a first current amplifier 510, a first volt-to-frequency converter 520, a second current amplifier 610, a second volt-to-frequency converter 620, a collector 700 and a host computer 800, wherein the sample stage 400 is used to place the sample 410, the first current amplifier 510 is connected to the X-ray absorption element 300, the first volt-to-frequency converter 520 is connected to the first current amplifier 510, the second current amplifier 610 is connected to the sample 410, and the second volt-to-frequency converter 620 is connected to the second The current amplifier 610 is connected, the collector 700 is connected to the first V / F converter 520 and the second V / F converter 620 respectively, and the host computer 800 is connected to the collector 700; the undulator 100 is used to emit X-rays, and the X-rays pass through the monochromator 200, the X-ray absorption element 300 and the sample 410 in sequence. The monochromator 200 is used to adjust the energy of the X-rays. After the X-rays are irradiated on the X-ray absorption element 300, part of them is absorbed by the X-ray absorption element 300, and the rest passes through the X-ray absorption element 300 and irradiates on the sample 410. After the X-rays are absorbed by the X-ray absorption element 300, the first light is generated due to the photoelectric effect. The first current amplifier 510 is used to receive the first photocurrent signal generated by the X-ray absorption element 300 and amplify the first photocurrent signal into a first voltage signal. The first volt-to-frequency converter 520 is used to receive the first voltage signal and convert the first voltage signal into a first frequency signal. The X-rays irradiated on the sample 410 are partially absorbed by the sample 410, and the rest pass through the sample 410. After the sample 410 absorbs the X-rays, a second photocurrent signal is generated due to the photoelectric effect. The intensity of the second photocurrent signal is proportional to the intensity of the X-rays absorbed by the X-ray absorption element 300. The second current amplifier 610 is used to receive the second photocurrent signal generated by the sample 410 and amplify the second photocurrent signal into a second voltage signal. The second volt-to-frequency converter 620 is used to receive the second voltage signal and convert the second voltage signal into a second frequency signal. The collector 700 is used to collect the first frequency signal to obtain the first collection data, and to collect the second frequency signal to obtain the second collection data. The host computer 800 is used to receive the first collection data and the second collection data, and obtain the X-ray absorption spectrum of the sample 410 according to the first collection data and the second collection data.

[0019] In some embodiments, the X-ray absorption element 300 may be a gold mesh. The gold mesh is a mesh structure woven by gold wires. The weaving density of the gold mesh can be expressed by the mesh number. The higher the mesh number, the more mesh holes the gold mesh has, and the weaker the X-ray absorption ability is. For example, the mesh number of the gold mesh can be set to 500. At this time, when X-rays are irradiated on the gold mesh, 10% of the X-rays will be absorbed by the gold mesh, and the remaining 90% of the X-rays will pass through the gold mesh. In other embodiments, the X-ray absorption element 300 may also be a gold foil or a copper mesh.

[0020] In some embodiments, the X-ray absorption element 300 and the sample 410 are both located in a vacuum environment, while the first current amplifier 510 and the second current amplifier 610 are located in an atmospheric environment. The first photocurrent signal generated by the X-ray absorption element 300 and the second photocurrent signal generated by the sample 410 can be transmitted to the vacuum flange through vacuum wires, respectively. The vacuum flange is connected to a high-shielded wire and is respectively connected to the first current amplifier 510 and the second current amplifier 610 through BNC (Bayonet Nut Connector) connectors, thereby realizing the transmission of signals from the vacuum environment to the atmospheric environment.

[0021] In some embodiments, the first current amplifier 510 and the second current amplifier 610 can both adopt Stanford R570 model current amplifiers, which have the functions of high bandwidth, high gain, low drift, and low noise, can suppress the background dark current of the input signal, and can eliminate high-frequency noise due to the built-in filter. It also has a maximum gain of 1 picoampere (PA) / volt (V), high sensitivity, and can convert weak current signals into larger voltage signals.

[0022] In some embodiments, the first frequency signal and the second frequency signal are both continuous rectangular pulse signals (logic level signals), and the amplitude of the pulse signal can be set to 5V, so that the influence of electromagnetic interference can be reduced during long-distance transmission. The first and second volt-to-frequency converters can use V2F100 model converters, which are linear voltage frequency converters for beam monitoring, which have two channels, and the voltage signal is converted into a frequency signal of 100MHz.

[0023] In some embodiments, the collector 700 has the function of collecting high-speed rectangular waves, and is used to collect rectangular pulse signals output by the volt-to-frequency converter, accumulate the number of pulse signals, store them, and upload them to the host computer 800. Specifically, Figure 2As shown, the collector 700 may include an FMC to double-row pin module 710, an FPGA (field programmable gate array) board 720 and a switch 730. The FMC to double-row pin module 710 is used to convert the logic level signal of the volt-frequency converter into a digital signal of 0 and 1, and transmit the digital signal to the FPGA board 720; wherein 0 represents a low-level signal in the logic level signal, and 1 represents a high-level signal in the logic level signal. The FPGA board 720 includes an FPGA chip, an optical module interface, a clock source, etc. The functions implemented by the FPGA board 720 include: built-in acquisition time t0, completing the digital signal waveform counting within the t0 time, storing and uploading to the host computer 800 in real time. The FPGA chip can be an AMD KINTEX UltraScale chip, model XCKU040-2FFVA1156I, including 4GB high-speed DDR4 and SDRAM, which can quickly read the multi-channel digital signal provided by the FMC to double-row pin module 710.

[0024] In some embodiments, the functional circuit of the FPGA chip can be designed by VIVADO software, a bitstream file can be generated, and the bitstream file can be solidified on the FPGA board 720 to realize different functions. The FPGA chip includes multiple functional modules such as a pulse acquisition module, a multi-function trigger module, a data storage module, and a network communication module. The functions of each module are as follows: Pulse acquisition module: accumulates rectangular pulse signals; records the total number of pulse signals within time t0 by identifying the digital signal transmitted by the FMC to double-row needle module 710, and outputs a value representing the pulse signal count within time t0.

[0025] Multi-function trigger module: Set signal acquisition parameters; including built-in acquisition time t0 (also called the first time) and external acquisition time (also called the second time). t0 represents the time to complete a pulse signal accumulation, and t1 represents continuous accumulation of multiple pulse signals; that is, after setting t0 and t1, the pulse acquisition module will accumulate multiple pulse signals, with a duration of t1 and each pulse signal accumulation time of t0, thereby obtaining n data, which form a 1×n one-dimensional array, where n=t1 / t0, so t1 needs to be an integer multiple of t0.

[0026] Data storage module: stores data. It stores the collected data generated in the pulse collection module and can be read by the host computer 800.

[0027] Network communication module: provides high-speed communication protocol between the host computer 800 and the FPGA board, used for communication between the host computer and the FPGA board.

[0028] The optical module interface can be an SFP (Small Form-factor Pluggable) interface, which can convert gigabit electrical signals into optical signals, and has the characteristics of high-speed data transmission and physical compactness. For example, an FPGA board may include four 10Gbps optical SFP interfaces, which are connected to switches through optical fibers to achieve long-distance, high-bandwidth, and highly stable transmission of signals.

[0029] The clock source is used to provide the system clock for the functional circuit of the FPGA chip, and to drive the pulse acquisition module, the multi-function trigger module, the data storage module and the network communication module to work. Specifically, a 200MHz differential clock source can be used to drive the pulse acquisition module, the multi-function trigger module and the data storage module to work, and a 150MHz differential clock source can be used to drive the network communication module to work. Since the pulse acquisition module is driven by 200MHz, it generates a clock signal every 5 nanoseconds, and the FPGA chip can trigger a functional operation on a clock signal. Therefore, the pulse acquisition module can recognize a digital signal within 5 nanoseconds, and the built-in acquisition time t0 can be as small as 5 nanoseconds.

[0030] The switch may be a 10G communication switch, which receives a signal from the FPGA chip, outputs the received signal to the host computer 800, and finally transmits the collected data to the host computer 800.

[0031] In some embodiments, the X-ray absorption spectrum acquisition device may further include a controller 900, the host computer 800 is connected to the controller 900, and the controller 900 is respectively connected to the undulator 100 and the monochromator 200, and the controller 900 is used to control the GAP of the undulator 100 and the energy of the X-rays emitted from the monochromator 200 according to the control instructions sent by the host computer 800, so that X-rays of different energies can pass through the X-ray absorption element 300 and the sample 410 in sequence. Specifically, the GAP of the undulator 100 can be achieved by moving the magnet, and the movement of the magnet is usually driven by a magnet motor, so the controller 900 can be connected to the magnet motor and adjust the GAP of the undulator 100 by controlling the operation of the magnet motor; the monochromator 200 includes a grating and a monochromator, and the grating and the monochromator are respectively driven by their own motors to move, and the controller 900 can be respectively connected to the motors of the grating and the monochromator, and adjust the energy of the X-rays emitted from the monochromator 200 by controlling the operation of the motors.

[0032] The principle of X-ray absorption spectrum collection is as follows: The host computer 800 adjusts the GAP of the undulator 100 and the energy value of the X-ray of the monochromator 200, so that the X-ray of the monochromator 200 is at different energies. For each energy of X-ray, the GAP of the undulator 100 is the optimal value corresponding to the energy, wherein the correspondence between the optimal value of the GAP and the energy of the X-ray can be obtained in advance; for each energy of X-ray, the X-ray of the energy will pass through the X-ray absorption element 300 and the sample 410 in turn, and the X-ray absorption element 300 and the sample 410 will respectively generate the first photocurrent signal and the second photocurrent signal under the energy. The collector 700 can be set to accumulate multiple pulse signals of the first frequency signal within a preset external acquisition time t1 under each energy of X-ray, and obtain multiple first accumulated values ​​as the first acquisition data; and accumulate multiple pulse signals of the second frequency signal to obtain multiple second accumulated values ​​as the second acquisition data; the time for each pulse signal accumulation is the preset built-in acquisition time t0, so t1 / t0 first accumulated values ​​and t1 / t0 second accumulated values ​​can be obtained under each energy of X-ray. The host computer 800 can calculate the X-ray absorption spectrum of the sample 410 according to each first acquisition data and each second acquisition data.

[0033] In some embodiments, the method in which the host computer 800 calculates the X-ray absorption spectrum of the sample 410 according to each first acquisition data and each second acquisition data is as follows: Assume that the number of different X-ray energies during the entire acquisition process is m, that is, data under X-rays of m energies are collected in sequence; t1 / t0=n, that is, under each energy of X-ray, the collector 700 can collect n first cumulative values ​​and n second cumulative values, and the host computer 800 can add up the n first cumulative values ​​under each energy of X-ray to obtain the first cumulative total value under each energy of X-ray. For example, the first cumulative total value under the i-th energy of X-ray can be recorded as Ai (i=1,2...m), and the n first cumulative values ​​under each energy of X-ray can be recorded as Ai (i=1,2...m). The first cumulative values ​​are averaged to obtain the first cumulative average value under each energy of X-ray, for example, the first cumulative average value under the i-th energy of X-ray can be recorded as Bi; then the minimum value Amin of each first cumulative total value can be obtained, Amin=min{A1, A2..., Am}, according to the first cumulative total value and the first cumulative average value under each energy of X-ray and the minimum value of each first cumulative total value, the number of first cumulative values ​​eliminated under the energy of X-ray can be obtained, for example, the number of first cumulative values ​​eliminated under the i-th energy of X-ray ,in, Indicates that x is rounded up; then, the first cumulative values ​​under the X-ray of each energy are eliminated according to the first cumulative elimination number of the X-ray of that energy to obtain the eliminated first cumulative values ​​under the X-ray of that energy, and the eliminated first cumulative values ​​under the X-ray of that energy are re-summed to obtain the optimized first cumulative total value under the X-ray of that energy. For example, for the first cumulative values ​​under the i-th energy of the X-ray, the last Ui of them can be eliminated, and there are n-Ui first cumulative values ​​after elimination. By adding them up, the optimized first cumulative total value under the i-th energy of the X-ray can be obtained, which is recorded as Ci; similarly, the collector 700 can add the n second cumulative values ​​under each energy of the X-ray, The second cumulative total value under each energy of X-ray is obtained, for example, the second cumulative total value under the i-th energy of X-ray can be recorded as Di (i=1,2...m), and the n second cumulative values ​​under each energy of X-ray are averaged to obtain the second cumulative average value under each energy of X-ray, for example, the second cumulative average value under the i-th energy of X-ray can be recorded as Fi; then the minimum value Dmin of each second cumulative total value can be obtained, Dmin=min{D1, D2..., Dm}, according to the second cumulative total value and the second cumulative average value under each energy of X-ray and the minimum value of each second cumulative total value, the number of second cumulative values ​​to be eliminated under the energy can be obtained, for example, the number of second cumulative values ​​to be eliminated under the i-th energy of X-ray ,in, Indicates that x is rounded up; then, the second cumulative values ​​under the X-ray of each energy are eliminated according to the second cumulative elimination number under the X-ray of that energy to obtain the eliminated second cumulative values ​​under the X-ray of that energy, and the eliminated second cumulative values ​​under the X-ray of that energy are re-summed to obtain the optimized second cumulative total value under the X-ray of that energy. For example, for each second cumulative value under the X-ray of the i-th energy, the latter Vi can be eliminated, and there are n-Vi second cumulative values ​​after elimination. By adding them up, the optimized second cumulative total value under the X-ray of the i-th energy can be obtained, which is recorded as Hi; then the absorption coefficient under the X-ray of each energy is obtained according to the optimized first cumulative total value and the optimized second cumulative total value, for example, the absorption coefficient under the X-ray of the i-th energy is XASi=Hi / Ci; each energy and the absorption coefficient under the X-ray of each energy form the X-ray absorption spectrum of sample 410.

[0034] In the X-ray absorption spectrum acquisition device of the embodiment of the present invention, the collector 700 synchronously acquires multiple first cumulative values ​​and multiple second cumulative values ​​under each energy of X-rays, and a more stable light intensity can be obtained by deleting a specified number of values ​​from the multiple first cumulative values ​​and the multiple second cumulative values, thereby improving the intensity stability of the reference light at different energy points and maintaining the signal synchronization between the X-ray absorption element 300 and the sample 410, thereby reducing the influence of the reference light flux oscillation on the X-ray absorption spectrum results and obtaining a more accurate X-ray absorption spectrum.

[0035] like Figure 3 As shown, an embodiment of the present invention further provides an X-ray absorption spectrum acquisition method, which includes the following steps: S1000: providing an X-ray absorption spectrum acquisition device as described in the above embodiment; S2000: The undulator 100 emits X-rays, and the upper computer 800 adjusts the energy of the X-rays emitted from the monochromator 200 and the magnet spacing (i.e., GAP) of the undulator 100, so that the X-rays emitted from the monochromator 200 are at different energies, and under each energy of the X-rays, the magnet spacing of the undulator 100 is the optimal value corresponding to the energy; S3000: Under each energy of X-ray, the first current amplifier 510 amplifies the first photocurrent signal generated by the X-ray absorption element 300 into a first voltage signal, the first V / F converter 520 converts the first voltage signal into a first frequency signal, the second current amplifier 610 amplifies the second photocurrent signal generated by the sample 410 into a second voltage signal, and the second V / F converter 620 converts the second voltage signal into a second frequency signal; S4000: Under each energy of X-ray, the collector 700 collects a first frequency signal under the energy of X-ray to obtain first collected data; and collects a second frequency signal under the energy of X-ray to obtain second collected data; S5000: The host computer 800 determines the X-ray absorption spectrum of the sample 410 according to the first acquisition data and the second acquisition data under the X-rays of different energies.

[0036] In some embodiments, step S4000 specifically includes: Under each energy of X-ray, according to the external acquisition time t1 and the internal acquisition time t0 sent in advance by the host computer 800 to the collector 700, the collector 700 accumulates the pulse signals of the first frequency signal multiple times within the external acquisition time t1 to obtain multiple first accumulated values ​​as the first acquisition data; and accumulates the pulse signals of the second frequency signal multiple times to obtain multiple second accumulated values ​​as the second acquisition data; wherein the time for each pulse signal accumulation is the internal acquisition time t0, and therefore t1 / t0 first accumulated values ​​and t1 / t0 second accumulated values ​​can be obtained under each energy of X-ray.

[0037] In some embodiments, step S5000 specifically includes: For each energy of the X-ray, the host computer 800 sums and averages the first accumulated values ​​of the X-ray of the energy to obtain a first accumulated total value and a first accumulated average value of the X-ray of the energy; The host computer 800 obtains the minimum value of the first cumulative total values ​​under the X-ray of each energy as the minimum first cumulative total value; For each energy of the X-ray, the host computer 800 sums and averages the second accumulated values ​​of the X-ray of the energy to obtain the second accumulated total value and the second accumulated average value of the X-ray of the energy; The host computer 800 obtains the minimum value of the second cumulative total values ​​under the X-rays of each energy as the minimum second cumulative total value; For each energy of X-ray, the host computer 800 determines the number of first cumulative values ​​of X-rays of the energy to be removed according to the first cumulative total value, the first cumulative average value and the minimum first cumulative total value of the X-rays of the energy; and determines the number of second cumulative values ​​of X-rays of the energy to be removed according to the second cumulative total value, the second cumulative average value and the minimum second cumulative total value of the X-rays of the energy; the calculation method is as follows: , , where Ui is the number of first cumulative values ​​eliminated under the i-th energy of X-rays, Ai is the first cumulative total value under the i-th energy of X-rays, Amin is the minimum first cumulative total value, Bi is the first cumulative average value under the i-th energy of X-rays, Vi is the number of second cumulative values ​​eliminated under the i-th energy of X-rays, Di is the second cumulative total value under the i-th energy of X-rays, Dmin is the minimum second cumulative total value, and Fi is the second cumulative average value under the i-th energy of X-rays; For each energy of X-ray, the host computer 800 removes each first cumulative value of the X-ray of the energy according to the first cumulative number of X-rays removed under the energy (for example, the first cumulative value of the first cumulative number of removals that can be removed), and obtains each first cumulative value after removal under the X-ray of the energy; and removes each second cumulative value of the X-ray of the energy according to the second cumulative number of X-rays removed under the energy (for example, the second cumulative value of the second cumulative number of removals that can be removed), and obtains each second cumulative value after removal under the X-ray of the energy; For each energy of X-ray, the host computer 800 sums up the first cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized first cumulative total value under the X-ray of the energy; and sums up the second cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized second cumulative total value under the X-ray of the energy; For each energy of X-ray, the upper computer 800 determines the absorption coefficient under the energy of X-ray according to the optimized first cumulative total value and the optimized second cumulative total value under the energy of X-ray; the calculation method of the absorption coefficient is as follows: XASi=Hi / Ci; wherein, XASi is the absorption coefficient under the i-th energy of X-ray, Hi is the second cumulative total value under the i-th energy of X-ray, and Ci is the first cumulative total value under the i-th energy of X-ray; each energy and the absorption coefficient under each energy of X-ray forms the X-ray absorption spectrum of sample 410.

[0038] In the X-ray absorption spectrum acquisition method of the embodiment of the present invention, the collector 700 synchronously acquires multiple first cumulative values ​​and multiple second cumulative values ​​under each energy of X-rays, and a more stable light intensity can be obtained by deleting a specified number of values ​​from the multiple first cumulative values ​​and the multiple second cumulative values, thereby improving the intensity stability of the reference light at different energy points and maintaining the signal synchronization between the X-ray absorption element 300 and the sample 410, thereby reducing the influence of the reference light flux oscillation on the X-ray absorption spectrum results and obtaining a more accurate X-ray absorption spectrum.

[0039] To verify the effect, the acquisition device and method of the embodiment of the present invention are used to acquire the absorption spectrum of the Fe element. First, the starting value, ending value and step value of the X-ray energy are set in the host computer 100. The energy of the X-ray increases from the starting value, and the step value is increased each time until the ending value is reached. At the same time, the optimal value of the magnet spacing corresponding to different energy points of the X-ray is set in the host computer 100. When the X-ray reaches a certain energy, the magnet spacing is also at the optimal value corresponding to the energy. At the same time, the external acquisition time and the built-in acquisition time are set in the host computer 100. After setting, the device can automatically acquire the absorption spectrum of the Fe element. Figure 4The figure shows a comparison of the Fe element absorption spectrum obtained by the device and method of the present invention and the Fe element absorption spectrum obtained by the existing method, wherein the solid line is the Fe element absorption spectrum obtained by the existing method, and the dotted line is the Fe element absorption spectrum obtained by the device and method of the present invention. The small box in the upper right corner is an enlarged view of the X-ray absorption spectrum with energy from 690eV to 707.4eV. Figure 4 It can be seen that the Fe element absorption spectrum obtained by the device and method of the present invention is more stable and has smaller oscillations. The measurement error of the Fe element absorption spectrum obtained by the existing method is 0.5%, while the measurement error of the Fe element absorption spectrum obtained by the device and method of the present invention is 0.1%, which greatly reduces the error.

[0040] 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. An X-ray absorption spectrum acquisition device, characterized in that: The device comprises an undulator, a monochromator, an X-ray absorption element, a sample stage, a first current amplifier, a first volt-frequency converter, a second current amplifier, a second volt-frequency converter, a collector and a host computer. The sample stage is used to place samples. The first current amplifier is connected to the X-ray absorption element, the first volt-frequency converter is connected to the first current amplifier, the second current amplifier is connected to the sample, the second volt-frequency converter is connected to the second current amplifier, the collector is connected to the first volt-frequency converter and the second volt-frequency converter respectively, and the host computer is connected to the collector. The undulator is used to emit X-rays, the monochromator is used to receive the X-rays and adjust the energy of the X-rays so that X-rays of different energies pass through the X-ray absorption element and the sample in sequence. The X-ray absorption element is used to generate a first photocurrent signal after being irradiated with X-rays, the first current amplifier is used to amplify the first photocurrent signal into a first voltage signal, and the first volt-frequency converter is used to convert the first voltage signal into a first frequency signal; the sample generates a second photocurrent signal after being irradiated with X-rays, the second current amplifier is used to amplify the second photocurrent signal into a second voltage signal, and the second volt-frequency converter is used to convert the second voltage signal into a second frequency signal; the collector is configured to collect the first frequency signal to obtain first collection data, and to collect the second frequency signal to obtain second collection data; the host computer is configured to determine the X-ray absorption spectrum of the sample based on the first collection data and the second collection data.

2. The X-ray absorption spectrum acquisition device according to claim 1, characterized in that: The first frequency signal and the second frequency signal are both continuous rectangular pulse signals.

3. The X-ray absorption spectrum acquisition device according to claim 1, characterized in that: The collector includes an FMC to double-row pin module, an FPGA board and a switch. The FMC to double-row pin module is used to convert the first frequency signal and the second frequency signal into digital signals of 0 and 1, and transmit the digital signals to the FPGA board; the FPGA board is used to collect the digital signals of the first frequency signal and the second frequency signal to obtain the first collected data and the second collected data, and transmit the first collected data and the second collected data to the host computer through the switch.

4. The X-ray absorption spectrum acquisition device according to claim 1, characterized in that: It also includes a controller, the host computer is connected to the controller, and the controller is respectively connected to the undulator and the monochromator, and is used to control the magnet spacing of the undulator and the energy of the X-ray emitted from the monochromator according to the control instructions sent by the host computer.

5. The X-ray absorption spectrum acquisition device according to claim 4, characterized in that: When the controller makes the X-ray emitted from the monochromator have each energy, the controller simultaneously makes the magnet spacing of the undulator become the optimal value corresponding to the X-ray of the energy.

6. The X-ray absorption spectrum acquisition device according to claim 1, characterized in that: The collector is specifically configured as follows: For each energy of X-ray, the first frequency signal is accumulated multiple times in a preset external acquisition time to obtain multiple first accumulated values ​​as first acquisition data; The second frequency signal is subjected to multiple pulse signal accumulation to obtain multiple second accumulated values ​​as second acquisition data; wherein the time for each pulse signal accumulation is a preset built-in acquisition time.

7. The X-ray absorption spectrum acquisition device according to claim 6, characterized in that: The host computer is specifically configured as follows: For each energy of the X-ray, summing and averaging the first accumulated values ​​of the X-ray of the energy to obtain a first accumulated total value and a first accumulated average value of the X-ray of the energy; and respectively summing and averaging the second accumulated values ​​under the X-ray energy to obtain a second accumulated total value and a second accumulated average value under the X-ray energy; Obtaining a minimum value among the first cumulative total values ​​under each energy of the X-ray and a minimum value among the second cumulative total values ​​under each energy of the X-ray, as the minimum first cumulative total value and the minimum second cumulative total value, respectively; For each energy of X-ray, determine the number of first cumulative values ​​of the X-ray of the energy to be removed according to the first cumulative total value and the first cumulative average value of the X-ray of the energy and the minimum first cumulative total value; And, determining the number of second cumulative values ​​to be eliminated under the energy of the X-ray according to the second cumulative total value, the second cumulative average value and the minimum second cumulative total value under the energy of the X-ray; For each energy of X-ray, first cumulative values ​​of X-rays under the energy are eliminated according to the first cumulative elimination number of X-rays under the energy, so as to obtain first cumulative values ​​after elimination of X-rays under the energy; and second cumulative values ​​of X-rays under the energy are eliminated according to the second cumulative elimination number of X-rays under the energy, so as to obtain second cumulative values ​​after elimination of X-rays under the energy; For each energy of X-ray, sum the first cumulative values ​​after elimination under the energy of X-ray to obtain the optimized first cumulative total value under the energy of X-ray; and summing up the eliminated second cumulative values ​​under the X-ray energy to obtain the optimized second cumulative total value under the X-ray energy; For each energy of X-ray, the absorption coefficient of the X-ray under the energy is determined according to the optimized first cumulative total value and the optimized second cumulative total value under the X-ray of the energy.

8. A method for collecting X-ray absorption spectra, characterized in that: include: Provide an X-ray absorption spectrum acquisition device as described in any one of claims 1 to 7; The undulator emits X-rays, and the energy of the X-rays emitted from the monochromator and the magnet spacing of the undulator are adjusted by the host computer, and under each energy of the X-rays, the magnet spacing of the undulator is the optimal value corresponding to the energy; Under each energy of X-ray, the first current amplifier amplifies the first photocurrent signal generated by the X-ray absorption element into a first voltage signal, the first volt-frequency converter converts the first voltage signal into a first frequency signal, the second current amplifier amplifies the second photocurrent signal generated by the sample into a second voltage signal, and the second volt-frequency converter converts the second voltage signal into a second frequency signal; Under each energy of X-ray, the collector collects the first frequency signal under the energy of X-ray to obtain first collected data; and collects the second frequency signal under the energy of X-ray to obtain second collected data; The host computer determines the X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data under the X-rays of various energies.

9. The X-ray absorption spectrum acquisition method according to claim 8, characterized in that: Under each energy of X-ray, the collector collects a first frequency signal under the energy of X-ray to obtain first collected data; The second frequency signal under the energy of X-ray is collected to obtain second collected data, which specifically includes: Under each energy of X-ray, according to the external acquisition time and the built-in acquisition time sent in advance to the collector by the host computer, the collector accumulates the pulse signals of the first frequency signal multiple times within the external acquisition time to obtain multiple first accumulated values ​​as the first acquisition data; and accumulates the pulse signals of the second frequency signal multiple times to obtain multiple second accumulated values ​​as the second acquisition data; wherein the time for each pulse signal accumulation is the built-in acquisition time.

10. The X-ray absorption spectrum collection method according to claim 9, characterized in that: Determining the X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data under the X-ray of each energy specifically includes: For each energy of the X-ray, summing and averaging the first accumulated values ​​of the X-ray of the energy to obtain a first accumulated total value and a first accumulated average value of the X-ray of the energy; Obtaining a minimum value among the first cumulative total values ​​under the X-ray of each energy as a minimum first cumulative total value; Obtaining a minimum value among the second cumulative total values ​​under the X-rays of each energy as a minimum second cumulative total value; For each energy of X-ray, the number of first cumulative values ​​of the X-ray under the energy to be eliminated is determined according to the first cumulative total value, the first cumulative average value and the minimum first cumulative total value of the X-ray under the energy; and the number of second cumulative values ​​of the X-ray under the energy to be eliminated is determined according to the second cumulative total value, the second cumulative average value and the minimum second cumulative total value of the X-ray under the energy; For each energy of X-ray, first cumulative values ​​of X-rays under the energy are eliminated according to the first cumulative elimination number of X-rays under the energy, so as to obtain first cumulative values ​​after elimination of X-rays under the energy; and second cumulative values ​​of X-rays under the energy are eliminated according to the second cumulative elimination number of X-rays under the energy, so as to obtain second cumulative values ​​after elimination of X-rays under the energy; For each energy of X-ray, sum the first cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized first cumulative total value under the X-ray of the energy; and sum the second cumulative values ​​after elimination under the X-ray of the energy to obtain the optimized second cumulative total value under the X-ray of the energy; For each energy of X-ray, the absorption coefficient of the X-ray under the energy is determined according to the optimized first cumulative total value and the optimized second cumulative total value under the X-ray of the energy.

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