X-ray Absorption Spectrum Acquisition Device and Method

Abstract

The present invention relates to an X-ray absorption spectrum acquisition device and method. The device includes an undulator, a monochromator, an X-ray absorption element, a sample stage, a first current amplifier, a first voltage-to-frequency converter, a second current amplifier, a second voltage-to-frequency converter, a collector, and a host computer. The sample stage is used to place a sample. The first current amplifier is connected to the X-ray absorption element. The first voltage-to-frequency converter is connected to the first current amplifier. The second current amplifier is connected to the sample. The second voltage-to-frequency converter is connected to the second current amplifier. The collector is respectively connected to the first voltage-to-frequency converter and the second voltage-to-frequency converter. The host computer is connected to the collector. The X-ray absorption spectrum acquisition device and method of the present invention can improve the stability of the reference light and reduce the influence of the reference light flux oscillation on the X-ray absorption spectrum result.

Description

Technical Field

[0001] The present invention relates to the technical field of X-ray absorption spectrum acquisition, and more particularly 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. The study of the relationship between the transmitted intensity and the incident X-ray intensity is called X-ray absorption spectroscopy. X-ray absorption spectrum is a powerful material characterization means, which includes X-ray absorption near edge structure and extended X-ray absorption fine structure. X-ray absorption spectrum is a technique for studying the relationship between the intensity attenuation of X-rays passing 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, and the absorption effect is much greater than the scattering effect. Synchrotron radiation X-ray absorption spectrum includes two detection modes: total electron yield mode (TEY) and total fluorescence yield (TFY), which are respectively used for detecting the electronic structure information of the surface and bulk elements of substances. Among them, the TEY mode obtains the data of the X-ray absorption spectrum by measuring the total amount of photoelectrons generated on the sample surface due to X-ray excitation. In this mode, electrons in the sample surface or near-surface region are excited and escape, so the TEY mode is very sensitive to the sample surface. The TFY mode obtains the data of the X-ray absorption spectrum by measuring the fluorescence signal emitted by the sample due to X-ray excitation. In this mode, the information of the sample bulk is detected because the fluorescence signal can penetrate a deeper region of the sample. The undulator light source is a key component used in synchrotron radiation light 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 will oscillate under the action of the periodic magnetic field, thereby emitting optical radiation. For the 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 performing spectroscopy experiments, in order to maintain the maximum light flux, the GAP value at each energy point is different. Therefore, when reaching a new energy point, it is necessary to adjust the size of the GAP, which is the GAP joint adjustment.

[0003] In X-ray absorption spectrum experiments, the reference light signal and the sample signal are usually normalized to obtain the final X-ray absorption spectrum. In the X-ray absorption spectrum experiment, the GAP joint adjustment will cause the reference light flux to jitter, which will affect the measurement accuracy and repeatability of the X-ray absorption spectrum. Among them, the absorption spectrum signal of trace elements is weak, and the signal-to-noise ratio of the absorption spectrum is extremely susceptible to the influence of the reference light flux jitter. 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 the reference light and reduce the influence of the reference light flux oscillation on the X-ray absorption spectrum result.

[0005] Based on the above object, on the one hand, the present invention provides an X-ray absorption spectrum acquisition device, including an undulator, a monochromator, an X-ray absorption element, a sample stage, a first current amplifier, a first voltage-frequency converter, a second current amplifier, a second voltage-frequency converter, a collector and a host computer. The sample stage is used for placing a sample. The first current amplifier is connected to the X-ray absorption element. The first voltage-frequency converter is connected to the first current amplifier. The second current amplifier is connected to the sample. The second voltage-frequency converter is connected to the second current amplifier. The collector is respectively connected to the first voltage-frequency converter and the second voltage-frequency converter. The host computer is connected to the collector. The undulator is used for emitting X-rays. The monochromator is used for receiving the X-rays and adjusting the energy of the X-rays so that X-rays with different energies pass through the X-ray absorption element and the sample in sequence. The X-ray absorption element is used for generating a first photocurrent signal after being irradiated by X-rays. The first current amplifier is used for amplifying the first photocurrent signal into a first voltage signal. The first voltage-frequency converter is used for converting the first voltage signal into a first frequency signal. The sample generates a second photocurrent signal after being irradiated by X-rays. The second current amplifier is used for amplifying the second photocurrent signal into a second voltage signal. The second voltage-frequency converter is used for converting the second voltage signal into a second frequency signal. The collector is configured to collect the first frequency signal to obtain first acquisition data and collect the second frequency signal to obtain second acquisition data. The host computer is configured to determine the X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data.

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

[0007] Further, 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 for converting the first frequency signal and the second frequency signal into digital signals of 0 and 1 and transmitting the digital signals to the FPGA board. The FPGA board is used for collecting the digital signals of the first frequency signal and the second frequency signal to obtain the first acquisition data and the second acquisition data and transmitting the first acquisition data and the second acquisition data to the host computer through the switch.

[0008] Further, it further 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 configured to control the magnet spacing of the undulator and the energy of the X-ray emitted from the monochromator according to the control instruction sent by the host computer.

[0009] Further, when the X-ray emitted from the monochromator is at each energy, the controller simultaneously makes the magnet spacing of the undulator be the optimal value corresponding to the X-ray of this energy.

[0010] Further, the collector is specifically arranged as follows:

[0011] For the X-ray of each energy, within the preset external acquisition time, the first frequency signal is subjected to multiple pulse signal accumulations to obtain multiple first cumulative values as the first acquisition data; and the second frequency signal is subjected to multiple pulse signal accumulations to obtain multiple second cumulative values as the second acquisition data; wherein, the time for each pulse signal accumulation is the preset internal acquisition time.

[0012] Further, the host computer is specifically arranged as follows:

[0013] For the X-ray of each energy, the first cumulative values under the X-ray of this energy are respectively summed and averaged to obtain the total first cumulative value and the average first cumulative value under the X-ray of this energy; and the second cumulative values under the X-ray of this energy are respectively summed and averaged to obtain the total second cumulative value and the average second cumulative value under the X-ray of this energy;

[0014] The minimum value among the total first cumulative values under the X-rays of each energy and the minimum value among the total second cumulative values under the X-rays of each energy are obtained, and are respectively used as the minimum total first cumulative value and the minimum total second cumulative value;

[0015] For the X-ray of each energy, the number of first cumulative values to be excluded under the X-ray of this energy is determined according to the total first cumulative value, the average first cumulative value under the X-ray of this energy, and the minimum total first cumulative value; and the number of second cumulative values to be excluded under the X-ray of this energy is determined according to the total second cumulative value, the average second cumulative value under the X-ray of this energy, and the minimum total second cumulative value;

[0016] For the X-ray of each energy, the first cumulative values under the X-ray of this energy are excluded according to the number of first cumulative values to be excluded under the X-ray of this energy to obtain the excluded first cumulative values under the X-ray of this energy; and the second cumulative values under the X-ray of this energy are excluded according to the number of second cumulative values to be excluded under the X-ray of this energy to obtain the excluded second cumulative values under the X-ray of this energy;

[0017] For each energy of X-ray, sum up each of the first cumulative values after rejection under the X-ray of that energy to obtain the optimized total first cumulative value under the X-ray of that energy; and sum up each of the second cumulative values after rejection under the X-ray of that energy to obtain the optimized total second cumulative value under the X-ray of that energy.

[0018] For each energy of X-ray, determine the absorption coefficient under the X-ray of that energy according to the optimized total first cumulative value and the optimized total second cumulative value under the X-ray of that energy.

[0019] On the other hand, the present invention provides an X-ray absorption spectrum acquisition method, which includes:

[0020] Provide an X-ray absorption spectrum acquisition device as described above;

[0021] Make the undulator emit X-rays, adjust the energy of the X-rays emitted from the monochromator and the magnet spacing of the undulator through the host computer, and at each energy of X-ray, the magnet spacing of the undulator is the optimal value corresponding to that energy;

[0022] At 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 voltage-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 voltage-frequency converter converts the second voltage signal into a second frequency signal;

[0023] At each energy of X-ray, the collector collects the first frequency signal under the X-ray of that energy to obtain first acquisition data; and collects the second frequency signal under the X-ray of that energy to obtain second acquisition data;

[0024] 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 each energy.

[0025] Further, at each energy of X-ray, the collector collects the first frequency signal under the X-ray of that energy to obtain first acquisition data; and collects the second frequency signal under the X-ray of that energy to obtain second acquisition data, which specifically includes:

[0026] At each energy of X-ray, according to the external acquisition time and the internal acquisition time pre-sent by the host computer to the collector, the collector accumulates the first frequency signal multiple times within the external acquisition time to obtain multiple first cumulative values as the first acquisition data; and accumulates the second frequency signal multiple times to obtain multiple second cumulative values as the second acquisition data; wherein the time for each pulse signal accumulation is the internal acquisition time.

[0027] Further, the X-ray absorption spectrum of the sample is determined according to the first acquisition data and the second acquisition data under X-rays of each energy, specifically including:

[0028] For the X-rays of each energy, the first cumulative values under the X-rays of this energy are respectively summed and averaged to obtain the first cumulative total value and the first cumulative average value under the X-rays of this energy;

[0029] Obtain the minimum value among the first cumulative total values under the X-rays of each energy as the minimum first cumulative total value;

[0030] Obtain the minimum value among the second cumulative total values under the X-rays of each energy as the minimum second cumulative total value;

[0031] For the X-rays of each energy, determine the number of first cumulative values to be excluded under the X-rays of this energy according to the first cumulative total value, the first cumulative average value and the minimum first cumulative total value under the X-rays of this energy; and determine the number of second cumulative values to be excluded under the X-rays of this energy according to the second cumulative total value, the second cumulative average value and the minimum second cumulative total value under the X-rays of this energy;

[0032] For the X-rays of each energy, exclude the first cumulative values under the X-rays of this energy according to the number of first cumulative values to be excluded under the X-rays of this energy to obtain the excluded first cumulative values under the X-rays of this energy; and exclude the second cumulative values under the X-rays of this energy according to the number of second cumulative values to be excluded under the X-rays of this energy to obtain the excluded second cumulative values under the X-rays of this energy;

[0033] For the X-rays of each energy, sum the excluded first cumulative values under the X-rays of this energy to obtain the optimized first cumulative total value under the X-rays of this energy; and sum the excluded second cumulative values under the X-rays of this energy to obtain the optimized second cumulative total value under the X-rays of this energy;

[0034] For the X-rays of each energy, determine the absorption coefficient under the X-rays of this energy according to the optimized first cumulative total value and the optimized second cumulative total value under the X-rays of this energy.

[0035] The X-ray absorption spectrum acquisition device and method of the present invention. The collector synchronously acquires a plurality of first cumulative values and a plurality of second cumulative values under X-rays of each energy. By deleting a specified number of values from the plurality of first cumulative values and the plurality of second cumulative values, a more stable light intensity can be obtained, improving the intensity stability of different energy points of the reference light, and maintaining the signal synchronization of the X-ray absorption element and the sample. Thus, the influence of the reference light flux oscillation on the X-ray absorption spectrum result can be reduced, and a more accurate X-ray absorption spectrum can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 FIG. is a schematic structural diagram of an X-ray absorption spectrum acquisition device according to an embodiment of the present invention;

[0037] Figure 2 FIG. is a structural block diagram of a collector of an X-ray absorption spectrum acquisition device according to an embodiment of the present invention;

[0038] Figure 3 FIG. is a flowchart of an X-ray absorption spectrum acquisition method according to an embodiment of the present invention;

[0039] Figure 4 FIG. is a comparison diagram of an Fe element absorption spectrum obtained by using the device and method of the present invention and an Fe element absorption spectrum obtained by using an existing method. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] The following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings.

[0041] As Figure 1As shown in the figure, an embodiment of the present invention provides an X-ray absorption spectrum acquisition device, which includes an undulator 100, a monochromator 200, an X-ray absorption element 300, a sample stage 400, a first current amplifier 510, a first voltage-to-frequency converter 520, a second current amplifier 610, a second voltage-to-frequency converter 620, a collector 700, and a host computer 800. The sample stage 400 is used to place a sample 410. The first current amplifier 510 is connected to the X-ray absorption element 300, the first voltage-to-frequency converter 520 is connected to the first current amplifier 510, the second current amplifier 610 is connected to the sample 410, the second voltage-to-frequency converter 620 is connected to the second current amplifier 610, the collector 700 is respectively connected to the first voltage-to-frequency converter 520 and the second voltage-to-frequency converter 620, and the host computer 800 is connected to the collector 700. The undulator 100 is used to emit X-rays. The X-rays sequentially pass through the monochromator 200, the X-ray absorption element 300, and the sample 410. The monochromator 200 is used to adjust the energy of the X-rays. After the X-rays irradiate on the X-ray absorption element 300, part of them are absorbed by the X-ray absorption element 300, and the rest pass through the X-ray absorption element 300 and irradiate on the sample 410. After the X-ray absorption element 300 absorbs the X-rays, a first photocurrent signal is generated due to the photoelectric effect. The intensity of the first photocurrent signal is proportional to the intensity of the X-rays absorbed by the X-ray absorption element 300. 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 voltage-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 irradiating 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 sample 410. 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 voltage-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 first acquisition data and collect the second frequency signal to obtain second acquisition data. The host computer 800 is used to receive the first acquisition data and the second acquisition data and obtain the X-ray absorption spectrum of the sample 410 according to the first acquisition data and the second acquisition data.

[0042] In some embodiments, the X-ray absorption element 300 may be a gold mesh. The gold mesh is a mesh structure woven from gold wires. The weaving density of the gold mesh can be expressed in mesh count. The higher the mesh count, the more mesh holes the gold mesh has. Correspondingly, the X-ray absorption ability is weaker. For example, the mesh count of the gold mesh can be set to 500. At this time, when X-rays irradiate 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.

[0043] In some embodiments, both the X-ray absorption element 300 and the sample 410 are 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 respectively transmitted to the vacuum flange through vacuum wires. High-shielded wires are connected to the vacuum flange and are 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.

[0044] In some embodiments, both the first current amplifier 510 and the second current amplifier 610 can adopt a Stanford R570 model current amplifier, which has functions of high bandwidth, high gain, low drift, and low noise. It can suppress the input signal background dark current. Due to the built-in filter, high-frequency noise can be eliminated, and it can have a maximum gain of 1 picoampere (pA) / volt (V), with high sensitivity, and can convert weak current signals into larger voltage signals.

[0045] In some embodiments, both the first frequency signal and the second frequency signal are continuous rectangular pulse signals (logic level signals). The amplitude of the pulse signal can be set to 5V, so that the influence of electromagnetic interference and the like can be reduced during long-distance transmission. The first and second voltage-to-frequency converters can adopt a V2F100 model converter, which is a linear voltage-frequency converter for beam monitoring. It has two channels, and the voltage signal is converted into a frequency signal of 100 MHz.

[0046] In some embodiments, the collector 700 has the function of collecting high-speed rectangular waves, is used to collect the rectangular pulse signals output by the voltage-to-frequency converter, accumulates the number of pulse signals, stores them, and uploads them to the host computer 800. Specifically, as Figure 2As shown in the figure, 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 voltage-frequency converter into digital signals of 0 and 1, and transmit the digital signals to the FPGA board 720; among them, 0 represents the low-level signal in the logic level signal, and 1 represents the 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: internally setting the acquisition time t0, completing the digital signal waveform counting within the t0 time, storing it, and uploading it to the host computer 800 in real time. The FPGA chip can be an AMD KINTEX UltraScale chip, with the model number XCKU040-2FFVA1156I, which includes 4GB of high-speed DDR4 and SDRAM, and can quickly read the multi-channel digital signals provided by the FMC to double-row pin module 710.

[0047] In some embodiments, the functional circuit of the FPGA chip can be designed through VIVADO software to generate a bitstream file, which is solidified on the FPGA board 720 to achieve different functions. The FPGA chip includes multiple functional modules such as a pulse acquisition module, a multi-functional trigger module, a data storage module, and a network communication module. The functions of each module are as follows:

[0048] Pulse acquisition module: Accumulate rectangular pulse signals; by identifying the digital signals transmitted by the FMC to double-row pin module 710, record the total number of pulse signals within the t0 time, and output a value representing the pulse signal count within the t0 time.

[0049] Multi-functional trigger module: Set signal acquisition parameters; including internally setting the acquisition time t0 (also known as the first time) and the external acquisition time (also known as the second time). t0 represents the time to complete one accumulation of pulse signals, and t1 represents continuous multiple accumulations of pulse signals; that is, after setting t0 and t1, the pulse acquisition module will perform multiple accumulations of pulse signals, with a duration of t1, and the time for each accumulation of pulse signals is t0. Thus, n data are obtained, and these n data form a 1×n one-dimensional array, where n = t1 / t0. Therefore, t1 needs to be an integer multiple of t0.

[0050] Data storage module: Store data. Store the acquisition data generated in the pulse acquisition module, which can be read by the host computer 800.

[0051] Network communication module: Provide a high-speed communication protocol between the host computer 800 and the FPGA board for communication between the host computer and the FPGA board.

[0052] 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, the FPGA board can include 4 optical SFP interfaces of 10 Gbps, which are connected to the switch through optical fibers to achieve long-distance, high-bandwidth, and high-stability transmission of signals.

[0053] The clock source is used to provide the system clock for the functional circuits of the FPGA chip and drive the pulse acquisition module, multi-functional trigger module, data storage module, and network communication module to work. Specifically, a differential clock source of 200 MHz can be used to drive the pulse acquisition module, multi-functional trigger module, and data storage module to work, and a differential clock source of 150 MHz can be used to drive the network communication module to work. Since the pulse acquisition module is driven by 200 MHz to work and generates a clock signal every 5 nanoseconds, the FPGA chip can trigger a functional operation on one clock signal. Therefore, the pulse acquisition module can identify a digital signal within 5 nanoseconds, and the built-in acquisition time t0 can be as small as 5 nanoseconds at minimum.

[0054] A 10G communication switch can be used as the switch. It receives the signals from the FPGA chip, outputs the received signals to the host computer 800, and finally transmits the acquired data to the host computer 800.

[0055] 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. 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 sequentially pass through the X-ray absorption element 300 and the sample 410. 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. Therefore, 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 monochromatic mirror, and the grating and the monochromatic mirror are respectively driven by their own motors to move. The controller 900 can be respectively connected to the motors of the grating and the monochromatic mirror and adjust the energy of the X-rays emitted from the monochromator 200 by controlling the operation of the motors.

[0056] The acquisition principle of the X-ray absorption spectrum is as follows:

[0057] 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 the X-ray of each energy, the GAP of the undulator 100 is the optimal value corresponding to this energy, and the corresponding relationship between the optimal value of the GAP and the energy of the X-ray can be obtained in advance; for the X-ray of each energy, the X-ray of this energy will sequentially pass through the X-ray absorption element 300 and the sample 410, and cause the X-ray absorption element 300 and the sample 410 to generate the first photocurrent signal and the second photocurrent signal at this energy respectively. The collector 700 can be set to, under the X-ray of each energy, accumulate multiple pulse signals of the first frequency signal within the preset external acquisition time t1 to obtain multiple first cumulative values as the first acquisition data; and accumulate multiple pulse signals of the second frequency signal to obtain multiple second cumulative values as the second acquisition data; the time for each pulse signal accumulation is the preset internal acquisition time t0, so t1 / t0 first cumulative values and t1 / t0 second cumulative values can be obtained under the X-ray of each energy. 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.

[0058] In some embodiments, the method for the host computer 800 to calculate the X-ray absorption spectrum of the sample 410 according to each first acquisition data and each second acquisition data is as follows:

[0059] Assume that the number of different energies of the X-ray during the entire acquisition process is m, that is, the data under the X-ray of m energies are sequentially acquired; t1 / t0 = n, that is, under the X-ray of each energy, the collector 700 can acquire n first cumulative values and n second cumulative values. The host computer 800 can add the n first cumulative values under the X-ray of each energy to obtain the total first cumulative value under the X-ray of each energy. For example, the total first cumulative value under the X-ray of the i-th energy can be denoted as Ai (i = 1, 2... m). The n first cumulative values under the X-ray of each energy are averaged to obtain the average first cumulative value under the X-ray of each energy. For example, the average first cumulative value under the X-ray of the i-th energy can be denoted as Bi; then the minimum value Amin of each total first cumulative value can be obtained, Amin = min{A1, A2,..., Am}. According to the total first cumulative value, the average first cumulative value under the X-ray of each energy, and the minimum value of each total first cumulative value, the number of first cumulative value eliminations under the X-ray of this energy can be obtained. For example, the number of first cumulative value eliminations under the X-ray of the i-th energy , where Denote the ceiling of x; then, according to the first cumulative rejection count under the X-ray of each energy, reject each first cumulative value under the X-ray of that energy to obtain the remaining first cumulative values under the X-ray of that energy after rejection, and sum up the remaining first cumulative values under the X-ray of that energy after rejection again to obtain the optimized total first cumulative value under the X-ray of that energy. For example, for each first cumulative value under the X-ray of the i-th energy, the latter Ui of them can be rejected. After rejection, there are n - Ui first cumulative values, and adding them up can obtain the optimized total first cumulative value under the X-ray of the i-th energy, denoted as Ci; Similarly, the collector 700 can sum up the n second cumulative values under the X-ray of each energy to obtain the total second cumulative value under the X-ray of each energy. For example, the total second cumulative value under the X-ray of the i-th energy can be denoted as Di (i = 1, 2... m). Take the average of the n second cumulative values under the X-ray of each energy to obtain the average second cumulative value under the X-ray of each energy. For example, the average second cumulative value under the X-ray of the i-th energy can be denoted as Fi; Then, the minimum value Dmin of each total second cumulative value can be obtained, Dmin = min{D1, D2,..., Dm}. According to the total second cumulative value, the average second cumulative value, and the minimum value of each total second cumulative value under the X-ray of each energy, the rejection count of the second cumulative value under that energy can be obtained. For example, the rejection count of the second cumulative value under the X-ray of the i-th energy , where Denote the ceiling of x; then, according to the rejection count of the second cumulative value under the X-ray of each energy, reject each second cumulative value under the X-ray of that energy to obtain the remaining second cumulative values under the X-ray of that energy after rejection, and sum up the remaining second cumulative values under the X-ray of that energy after rejection again to obtain the optimized total second cumulative 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 of them can be rejected. After rejection, there are n - Vi second cumulative values, and adding them up can obtain the optimized total second cumulative value under the X-ray of the i-th energy, denoted as Hi; Then, according to the optimized total first cumulative value and the optimized total second cumulative value under the X-ray of each energy, the absorption coefficient under the X-ray of that energy can be obtained. For example, the absorption coefficient XASi under the X-ray of the i-th energy = Hi / Ci; Each energy and the absorption coefficient under the X-ray of each energy form the X-ray absorption spectrum of the sample 410.

[0060] In the X-ray absorption spectrum acquisition device according to an embodiment of the present invention, the collector 700 synchronously acquires a plurality of first cumulative values and a plurality of second cumulative values under X-rays of each energy. By deleting a specified number of values from the plurality of first cumulative values and the plurality of second cumulative values, a more stable light intensity can be obtained, the intensity stability of different energy points of the reference light is improved, and the signal synchronization of the X-ray absorption element 300 and the sample 410 is maintained. Thus, the influence of the reference light flux oscillation on the X-ray absorption spectrum result can be reduced, and a more accurate X-ray absorption spectrum can be obtained.

[0061] As Figure 3 shown, an embodiment of the present invention further provides an X-ray absorption spectrum acquisition method, which includes the following steps:

[0062] S1000: Provide an X-ray absorption spectrum acquisition device as described in the above embodiment;

[0063] S2000: Cause the undulator 100 to emit X-rays, and adjust the energy of the X-rays emitted from the monochromator 200 and the magnet gap (i.e., GAP) of the undulator 100 through the host computer 800, so that the X-rays emitted from the monochromator 200 are at different energies, and under X-rays of each energy, the magnet gap of the undulator 100 is the optimal value corresponding to this energy;

[0064] S3000: Under X-rays of each energy, 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 voltage-to-frequency 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 voltage-to-frequency converter 620 converts the second voltage signal into a second frequency signal;

[0065] S4000: Under X-rays of each energy, the collector 700 acquires the first frequency signal under the X-rays of this energy to obtain first acquisition data; and acquires the second frequency signal under the X-rays of this energy to obtain second acquisition data;

[0066] 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 X-rays of each energy.

[0067] In some embodiments, step S4000 specifically includes:

[0068] Under X-rays of each energy, according to the external acquisition time t1 and the internal acquisition time t0 pre-sent by the host computer 800 to the collector 700, the collector 700 accumulates the first frequency signal multiple times within the external acquisition time t1 to obtain multiple first cumulative values as the first acquisition data; and accumulates the second frequency signal multiple times to obtain multiple second cumulative values as the second acquisition data; where the time for each pulse signal accumulation is the internal acquisition time t0, so t1 / t0 first cumulative values and t1 / t0 second cumulative values can be obtained under X-rays of each energy.

[0069] In some embodiments, step S5000 specifically includes:

[0070] For X-rays of each energy, the host computer 800 sums and averages the respective first cumulative values under the X-rays of this energy to obtain the total first cumulative value and the average first cumulative value under the X-rays of this energy;

[0071] The host computer 800 obtains the minimum value among the total first cumulative values under X-rays of each energy as the minimum total first cumulative value;

[0072] For X-rays of each energy, the host computer 800 sums and averages the respective second cumulative values under the X-rays of this energy to obtain the total second cumulative value and the average second cumulative value under the X-rays of this energy;

[0073] The host computer 800 obtains the minimum value among the total second cumulative values under X-rays of each energy as the minimum total second cumulative value;

[0074] For X-rays of each energy, the host computer 800 determines the number of first cumulative value eliminations under the X-rays of this energy according to the total first cumulative value, the average first cumulative value and the minimum total first cumulative value under the X-rays of this energy; and determines the number of second cumulative value eliminations under the X-rays of this energy according to the total second cumulative value, the average second cumulative value and the minimum total second cumulative value under the X-rays of this energy; the calculation method is as follows: , , where Ui is the number of first cumulative value eliminations under the X-rays of the i-th energy, Ai is the total first cumulative value under the X-rays of the i-th energy, Amin is the minimum total first cumulative value, Bi is the average first cumulative value under the X-rays of the i-th energy, Vi is the number of second cumulative value eliminations under the X-rays of the i-th energy, Di is the total second cumulative value under the X-rays of the i-th energy, Dmin is the minimum total second cumulative value, and Fi is the average second cumulative value under the X-rays of the i-th energy;

[0075] For the X-rays of each energy, the host computer 800 eliminates each first cumulative value under the X-rays of this energy according to the first cumulative elimination number under the X-rays of this energy (for example, the first cumulative value after the elimination of the first cumulative elimination number) to obtain each eliminated first cumulative value under the X-rays of this energy; and, eliminates each second cumulative value under the X-rays of this energy according to the second cumulative elimination number under the X-rays of this energy (for example, the second cumulative value after the elimination of the second cumulative elimination number) to obtain each eliminated second cumulative value under the X-rays of this energy;

[0076] For the X-rays of each energy, the host computer 800 sums up each eliminated first cumulative value under the X-rays of this energy to obtain the optimized total first cumulative value under the X-rays of this energy; and, sums up each eliminated second cumulative value under the X-rays of this energy to obtain the optimized total second cumulative value under the X-rays of this energy;

[0077] For the X-rays of each energy, the host computer 800 determines the absorption coefficient under the X-rays of this energy according to the optimized total first cumulative value and the optimized total second cumulative value under the X-rays of this energy; the calculation method of the absorption coefficient is as follows: XASi = Hi / Ci; where, XASi is the absorption coefficient under the X-rays of the i-th energy, Hi is the total second cumulative value under the X-rays of the i-th energy, and Ci is the total first cumulative value under the X-rays of the i-th energy; the absorption coefficients of each energy and under the X-rays of each energy form the X-ray absorption spectrum of the sample 410.

[0078] In the X-ray absorption spectrum acquisition method of the embodiment of the present invention, the collector 700 synchronously acquires a plurality of first cumulative values and a plurality of second cumulative values under the X-rays of each energy. By deleting a specified number of values in the plurality of first cumulative values and the plurality of second cumulative values, a more stable light intensity can be obtained, the intensity stability of different energy points of the reference light is improved, and the signal synchronization of the X-ray absorption element 300 and the sample 410 is maintained. Thus, the influence of the reference light flux oscillation on the X-ray absorption spectrum result can be reduced, and a more accurate X-ray absorption spectrum can be obtained.

[0079] 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, set the starting value, ending value, and step value of the energy of the X-rays in the host computer 800. The energy of the X-rays starts to increase from the starting value, and each time it increases by the step value until it reaches the ending value; at the same time, set the optimal value of the magnet spacing corresponding to different energy points of the X-rays in the host computer 800. When the X-rays reach a certain energy, the magnet spacing is also at the optimal value corresponding to this energy; at the same time, set the external acquisition time and the internal acquisition time in the host computer 800; after setting, the device can automatically acquire the absorption spectrum of the Fe element. As Figure 4The figure shows 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. Among them, the solid line is the Fe element absorption spectrum obtained by the existing method, and the dashed line is the Fe element absorption spectrum obtained by using 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 an energy range of 690 eV to 707.4 eV. From Figure 4 It can be seen that the Fe element absorption spectrum obtained by using the device and method of the present invention is more stable and has less oscillation. 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%, greatly reducing the error.

[0080] The above are only the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various changes can be made to the above embodiments of the present invention. That is, any simple, equivalent changes and modifications made in accordance with the claims and the content of the specification of the present invention application shall fall within the scope of the claims of the present invention patent. The content not described in detail in the present invention is all conventional technical content.

Claims

1. An X-ray absorption spectrum acquisition device, characterized in that, It includes a wiggler, a monochromator, an X-ray absorption element, a sample stage, a first current amplifier, a first voltage-to-frequency converter, a second current amplifier, a second voltage-to-frequency converter, a collector and a host computer. The sample stage is used to place a sample. The first current amplifier is connected to the X-ray absorption element. The first voltage-to-frequency converter is connected to the first current amplifier. The second current amplifier is connected to the sample. The second voltage-to-frequency converter is connected to the second current amplifier. The collector is respectively connected to the first voltage-to-frequency converter and the second voltage-to-frequency converter. The host computer is connected to the collector. The wiggler 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 with different energies sequentially pass through the X-ray absorption element and the sample. The X-ray absorption element is used to generate a first photocurrent signal after being irradiated by X-rays. The first current amplifier is used to amplify the first photocurrent signal into a first voltage signal. The first voltage-to-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 by X-rays. The second current amplifier is used to amplify the second photocurrent signal into a second voltage signal. The second voltage-to-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 acquisition data and collect the second frequency signal to obtain second acquisition data. The host computer is configured to determine the X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data; The collector is specifically configured as follows: For X-rays of each energy, multiple pulse signal accumulations are performed on the first frequency signal within a preset external acquisition time to obtain multiple first cumulative values, which are used as the first acquisition data; And multiple pulse signal accumulations are performed on the second frequency signal to obtain multiple second cumulative values, which are used as the second acquisition data. Wherein, the time for each pulse signal accumulation is a preset internal acquisition time; The host computer is specifically configured as follows: For X-rays of each energy, the first cumulative values under the X-rays of this energy are respectively summed and averaged to obtain the total first cumulative value and the average first cumulative value under the X-rays of this energy. And, the second cumulative values under the X-rays of this energy are respectively summed and averaged to obtain the total second cumulative value and the average second cumulative value under the X-rays of this energy; The minimum value among the total first cumulative values under the X-rays of each energy and the minimum value among the total second cumulative values under the X-rays of each energy are obtained and used as the minimum total first cumulative value and the minimum total second cumulative value respectively; For the X-rays of each energy, determine the number of first cumulative value exclusions for the X-rays of this energy according to the first cumulative total value, the first cumulative average value, and the minimum first cumulative total value under the X-rays of this energy; and, determine the number of second cumulative value exclusions for the X-rays of this energy according to the second cumulative total value, the second cumulative average value, and the minimum second cumulative total value under the X-rays of this energy; For the X-rays of each energy, starting from the end of each first cumulative value of the X-rays of this energy, exclude the number of first cumulative values corresponding to the number of first cumulative value exclusions for the X-rays of this energy to obtain the excluded first cumulative values for the X-rays of this energy; and, starting from the end of each second cumulative value of the X-rays of this energy, exclude the number of second cumulative values corresponding to the number of second cumulative value exclusions for the X-rays of this energy to obtain the excluded second cumulative values for the X-rays of this energy; For the X-rays of each energy, sum the excluded first cumulative values for the X-rays of this energy to obtain the optimized first cumulative total value for the X-rays of this energy; and, sum the excluded second cumulative values for the X-rays of this energy to obtain the optimized second cumulative total value for the X-rays of this energy; For the X-rays of each energy, determine the absorption coefficient for the X-rays of this energy according to the optimized first cumulative total value and the optimized second cumulative total value for the X-rays of this energy.

2. The X-ray absorption spectrum acquisition device according to claim 1, wherein Both the first frequency signal and the second frequency signal are 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 acquisition data and the second acquisition data, and transmit the first acquisition data and the second acquisition data to the host computer through the switch.

4. The X-ray absorption spectrum acquisition device according to claim 1, characterized in that, It further 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.

5. The X-ray absorption spectrum acquisition device according to claim 4, wherein, When the X-rays emitted from the monochromator are of each energy, the controller simultaneously makes the magnet spacing of the undulator the optimal value corresponding to the X-rays of this energy.

6. A method for collecting X-ray absorption spectra, characterized in that, Comprising: Provide an X-ray absorption spectrum acquisition device as described in any one of claims 1-5; Make the undulator emit X-rays, adjust the energy of the X-rays emitted from the monochromator and the magnet spacing of the undulator through the host computer, and at the X-rays of each energy, the magnet spacing of the undulator is the optimal value corresponding to this energy; Under X-rays of each energy, a first current amplifier amplifies a first photocurrent signal generated by an X-ray absorption element into a first voltage signal, a first voltage-frequency converter converts the first voltage signal into a first frequency signal, a second current amplifier amplifies a second photocurrent signal generated by a sample into a second voltage signal, and a second voltage-frequency converter converts the second voltage signal into a second frequency signal; Under X-rays of each energy, according to an external acquisition time and an internal acquisition time pre-sent by a host computer to an acquirer, the acquirer accumulates the first frequency signal multiple times within the external acquisition time to obtain multiple first cumulative values as the first acquisition data; and accumulates the second frequency signal multiple times to obtain multiple second cumulative values as the second acquisition data; wherein the time for each pulse signal accumulation is the internal acquisition time; The host computer determines an X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data under X-rays of each energy; Determining the X-ray absorption spectrum of the sample according to the first acquisition data and the second acquisition data under X-rays of each energy specifically includes: For X-rays of each energy, sum and average the respective first cumulative values under X-rays of this energy to obtain a first total cumulative value and a first average cumulative value under X-rays of this energy; Obtain the minimum value among the first total cumulative values under X-rays of each energy as the minimum first total cumulative value; Obtain the minimum value among the second total cumulative values under X-rays of each energy as the minimum second total cumulative value; For X-rays of each energy, determine the number of first cumulative values to be excluded under X-rays of this energy according to the first total cumulative value, the first average cumulative value, and the minimum first total cumulative value under X-rays of this energy; and determine the number of second cumulative values to be excluded under X-rays of this energy according to the second total cumulative value, the second average cumulative value, and the minimum second total cumulative value under X-rays of this energy; For X-rays of each energy, starting from the end of the respective first cumulative values under X-rays of this energy, exclude the number of first cumulative values corresponding to the number of first cumulative values to be excluded under X-rays of this energy to obtain the excluded first cumulative values under X-rays of this energy; and starting from the end of the respective second cumulative values under X-rays of this energy, exclude the number of second cumulative values corresponding to the number of second cumulative values to be excluded under X-rays of this energy to obtain the excluded second cumulative values under X-rays of this energy; For X-rays of each energy, sum the excluded first cumulative values under X-rays of this energy to obtain an optimized first total cumulative value under X-rays of this energy; and sum the excluded second cumulative values under X-rays of this energy to obtain an optimized second total cumulative value under X-rays of this energy; For X-rays of each energy, determine the absorption coefficient under X-rays of this energy according to the optimized first total cumulative value and the optimized second total cumulative value under X-rays of this energy.

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