JP2023107744A - Method and system for simultaneously executing x-ray absorption spectroscopy and fluorescent x-ray spectroscopic analysis - Google Patents

Abstract

To provide a method and a system for simultaneously executing X-ray absorption spectroscopy and fluorescent X-ray spectroscopic analysis.SOLUTION: A system includes an X-ray light source 100, at least one X-ray condensing lens constituted so as to radiate X rays having an absorption end of an element detected from an object 200 from an X-ray light source and an energy bandwidth higher than X-ray energy corresponding to the absorption end, and a supporting rack constituted so as to support the object 200 to be inspected. The energy bandwidth includes the X-ray energy corresponding to the absorption end and at least the one X-ray condensing lens is constituted so as to condense one portion of the X rays in a measurement spot on the object having a condensation size less than 500 μm. The system includes: at least one spatial decomposition X-ray detection device 410 constituted so as to detect X rays through the object 200; and at least one fluorescent X-ray detection device 400 constituted so as to detect X rays scattered from the object 200.SELECTED DRAWING: Figure 1

Description

The present invention relates to methods and systems for enabling simultaneous X-ray absorption spectroscopy (XAS) in transmission geometry and X-ray fluorescence spectroscopy (XRF) in fluorescence geometry.

In X-ray absorption spectroscopy, detectors are placed before and after the sample to measure X-ray intensity, and absorption spectra are obtained by measuring the intensity of incident X-rays and transmitted X-rays along the X-ray optical path. , X-rays are made monochromatic (aligned wavelengths). X-ray absorption spectroscopy spectrum (XAS: X-ray Absorption Spectra) or X-ray absorption fine structure (XAFS: X-ray Absorption Fine Structure) is an X-ray absorption near edge structure (XANES: X-ray Absorption Near Edge Structure) and wide-area X-ray absorption fine structure (XAFS: X-ray Absorption Fine Structure).
In an X-ray absorption spectrometer, it has also been proposed to observe wavelength-dispersive X-ray absorption spectroscopy using a spectroscope in a transmitted light arrangement (see, for example, Patent Document 1). However, when using transmitted X-rays, it is necessary to process the sample into a thin piece having a thickness of, for example, about 100 μm, which poses a problem that the shape of the sample that can be measured is limited.

Fluorescent X-ray analysis is a method for qualitative or quantitative analysis of a substance by irradiating an unknown substance with X-rays and measuring the fluorescent X-rays generated therefrom (see, for example, Non-Patent Document 1). ).
When a substance is irradiated with X-rays, fluorescent X-rays (characteristic X-rays) having energy (wavelength) unique to the elements constituting the substance are generated. By measuring the energy of this fluorescent X-ray, the contained element can be identified (qualitative analysis), and the concentration of each element can be calculated from the intensity of the fluorescent X-ray (quantitative analysis). Methods of X-ray fluorescence analysis include a wavelength dispersive type (WDXRF) using an analyzing crystal and an energy dispersive type (EDXRF) using a semiconductor detector (EDS).

By the way, in the physical property analysis of a sample, if the X-ray absorption spectroscopic analysis and the fluorescent X-ray analysis are performed by different apparatuses, it is difficult to precisely match the X-ray irradiation position of the sample. Since the physical properties change dynamically, it is not suitable for the purpose of observing the process of dynamic change.
Therefore, in order to observe changes in proteins and biological molecules at the molecular level, X-ray absorption spectroscopy and fluorescent X-ray analysis are performed simultaneously in large facilities such as high-intensity synchrotron radiation facilities, which allows us to determine the X-ray irradiation position of the sample. Observation of the process of dynamic change has been performed with close matching. Examples of high-intensity synchrotron radiation facilities include the facility described in Non-Patent Document 2, Japan's SPring-8 (registered trademark), and the like.

However, a high-intensity synchrotron radiation facility such as SPring-8 (registered trademark) has a large site area of 141 ha, and requires a power supply of about 18 MW to operate the accelerator and experimental equipment. , 77kV special high voltage power receiving facilities are installed. For this reason, it is large and lacks versatility, and installation and operating costs are major issues. In addition, an experiment plan is submitted to the operating organization of the facility, and only when it is approved after screening can the allocation of experiment time be received. There is also the problem that the number of time slots that are actually available to users is rather limited.

Japanese Patent No. 6937380

Principle and application of fluorescence XAFS method Yoshio Takahashi (2010) http://pfwww. kek. jp/innovationPF/04_EVENT/XAFS_Seminor_1010/fl-xafs. pdf GORIL JAHRSENGENE, et. al. An EXAFS and XANES Study of V, Ni, and Fe Specification in Cokes for Anodes Used in Aluminum Production "Metallurgical and Materials Transactions B Volume 50B December 2019-2971

The present invention solves the above-mentioned problems, and although it has the same level of equipment as a conventional small general-purpose X-ray absorption spectrometer, it performs X-ray absorption spectroscopy in the transmission arrangement and fluorescent X-ray analysis in the fluorescence arrangement. are performed simultaneously to precisely match the X-ray irradiation position of the sample and to provide a method and system capable of observing the process of dynamic change.

[1] The method of the present invention for simultaneously performing X-ray absorption spectroscopy (XAS) in transmission configuration and X-ray fluorescence spectroscopy (XRF) in fluorescence configuration comprises:
irradiating the object with X-rays having an energy bandwidth higher than and including the energy corresponding to the absorption edge of the element;
acquiring an x-ray absorption spectrum from the object over an energy bandwidth including the absorption edge with an energy resolution greater than 3 eV using a spatially resolving x-ray detector;
Acquiring a fluorescent X-ray spectrum by detecting X-rays scattered from the object using a fluorescent X-ray detection device;
is a method of providing

[2] In the method [1] of the present invention, preferably, the X-ray absorption spectrum obtained from the object using the spatially resolving X-ray detection device has energy up to 200 eV on the high energy side from the absorption edge First energy bandwidth information for obtaining an X-ray absorption near-edge structure (XANES) across the bandwidth, and an extended X-ray absorption fine structure ( and/or second energy bandwidth information for obtaining EXAFS).
[3] In the method [1] of the present invention, preferably, the fluorescent X-ray spectrum is an energy bandwidth outside the region of interest with respect to the spectral intensity of the region of interest of the energy bandwidth including the absorption edge of the element. Then, for the spectral intensity of the second region of interest in the energy bandwidth of the background region that does not include the absorption edge of the element, the average value in the energy bandwidth of the background region is obtained as the noise spectral intensity, and the region of interest The noise spectral intensity may be subtracted from the spectral intensity of the region of interest to obtain the true measured spectral intensity of the region of interest.
[4] In the method [3] of the present invention, preferably, the spectral intensity of the region of interest (ROI) of the energy bandwidth including the absorption edge of the element is obtained by counting the X-rays detected by the fluorescent X-ray detector. The true value of the count number of the X-rays is the noise spectrum used for the subtraction process of the noise spectrum intensity from the count number of the fluorescence X-ray spectrum before the noise spectrum intensity is subtracted. A formula for a value obtained by subtracting the proportional division ratio (BW/BW _BG ) according to the bandwidth of the fluorescent X-ray spectrum:
It is preferable to be calculated by
Here, True ROI counts is the true value of the number of X-ray counts, Raw ROI counts is the count number of fluorescent X-ray spectra before noise spectrum intensity is subtracted, ROI _BG counts is the noise spectrum intensity, and BW is the region of interest. , BW _BG is the energy bandwidth of the background region.

[5] A system for simultaneously performing X-ray absorption spectroscopy (XAS) in transmission configuration and X-ray fluorescence spectroscopy (XRF) in fluorescence configuration according to the present invention includes, for example, an X-ray light source 100 and , an X-ray absorption near-edge structure (XANES) over an energy bandwidth of 200 eV or less on the high-energy side from the absorption edge, corresponding to the absorption edge of an element contained in the object, from the X-ray source, or at least one configured to emit X-rays having an energy bandwidth suitable for measurements to obtain an extended X-ray absorption fine structure (EXAFS) over an energy bandwidth of 2 keV or less on the high energy side of the absorption edge; an X-ray condensing lens;
a support base configured to support the object 200 to be measured;
The energy bandwidth includes the X-ray energy corresponding to the absorption edge, and the at least one X-ray collecting lens directs at least a portion of the X-rays to the object having a collection size of less than 500 μm. configured to focus light onto the measurement spot above,
at least one spatially resolving X-ray detection device 410 configured to detect X-rays transmitted through the object 200;
at least one fluorescent X-ray detection device 400 configured to detect X-rays scattered from the object 200;
The X-ray condensing lens includes a first X-ray condensing mirror 110a installed on the side of the X-ray light source, a analyzing crystal 120 on which the X-rays reflected by the first X-ray condensing mirror are incident, and the spectroscopic lens. A system consisting of a second X-ray collecting mirror 110b, a slit 160 and an aperture 170 on which X-rays separated by the crystal are incident.

[6] In the system [5] of the present invention, preferably, the spatially resolving X-ray detection device has diodes with a pixel size of 25 μm or more and 1000 μm or less arranged two-dimensionally, has detection sensitivity in the X-ray region, and photon It is preferable that the detecting element has a counting function.
[7] In the system [5] of the present invention, preferably, the fluorescent X-ray detection device is a detection element having an energy resolution higher than 150 eV.
[8] In the system [5] of the present invention, preferably, the fluorescent X-ray detection device has a function of adjusting the position and angle of the object with respect to the X-rays emitted to the object. Good to have.
[9] In the system [5] of the present invention, the system preferably has an arithmetic device 420 that processes detection signals from the fluorescent X-ray detector,
When obtaining the fluorescent X-ray spectrum, the arithmetic unit 420 determines the spectral intensity of the region of interest of the energy bandwidth including the absorption edge of the element, the energy bandwidth outside the region of interest, and the For the spectral intensity of the energy bandwidth of the background region not including the absorption edge, the average value in the energy bandwidth of the background region is obtained, and the noise spectral intensity is obtained,
The noise spectral intensity may be subtracted from the spectral intensity of the region of interest to obtain the true measured spectral intensity of the region of interest.
[10] In the system [9] of the present invention, preferably, the spectral intensity of the region of interest (ROI) of the energy bandwidth including the absorption edge of the element is the count of the X-rays detected by the fluorescent X-ray detector is determined from a number,
The true value of the count number of the X-rays is the bandwidth of the noise spectrum fluorescence X-ray spectrum used for the subtraction process of the noise spectrum intensity from the count number of the fluorescence X-ray spectrum before the noise spectrum intensity is subtracted. A formula with a value after deducting the corresponding proportional division ratio (BW/BW _BG ):
It is preferable to be calculated by
Here, True ROI counts is the true value of the number of X-ray counts, Raw ROI counts is the count number of fluorescent X-ray spectra before noise spectrum intensity is subtracted, ROI _BG counts is the noise spectrum intensity, and BW is the region of interest. , BW _BG is the energy bandwidth of the background region.

According to the method and system for simultaneously performing X-ray absorption spectroscopy (XAS) in the transmission arrangement and X-ray fluorescence spectroscopy (XRF) in the fluorescence arrangement of the present invention, the same as the conventional compact general-purpose X-ray absorption spectrometer Although it is a small facility, X-ray absorption spectroscopic analysis in the transmission arrangement and X-ray fluorescence analysis in the fluorescence arrangement can be performed at the same time, and the X-ray irradiation position of the sample can be strictly determined in both the X-ray absorption spectroscopy and the X-ray fluorescence spectroscopy. , the object to be measured can be observed.
Also, according to the method and system for simultaneously performing X-ray absorption spectroscopy (XAS) in the transmission configuration and X-ray fluorescence spectroscopy (XRF) in the fluorescence configuration of the present invention, both absorption and fluorescence XAS observations are possible ( whichever is better), and when X-ray fluorescence spectroscopy is performed, signals are obtained from thick samples and low density materials that "transmission" cannot handle.

1 is an overall configuration diagram of an X-ray spectrometer, showing an embodiment of the present invention; FIG. 2 is a flow chart illustrating the measurement process of the device shown in FIG. 1; FIG. 10 is a diagram showing measurement results of a fluorescent X-ray spectrum, showing an embodiment of the present invention, showing a case where excitation light is fixed; FIG. 3 is a 3D display diagram showing measurement results of a fluorescent X-ray spectrum, showing an embodiment of the present invention, showing a case where Ni is measured by scanning excitation light. FIG. 4 is a 2D view showing the measurement results of the fluorescent X-ray spectrum, showing the case where Ni is measured by scanning the excitation light. FIG. 2 is a diagram showing an example of setting multiple regions of interest (ROI) and procedures in X-ray fluorescence analysis; FIG. 6B is a diagram for explaining the relationship of subtracting BG (background) matching the corresponding ROI width from a certain fluorescent X-ray peak in FIG. 6A. FIG. 10 is a diagram showing another example of setting multiple regions of interest (ROI) and procedures in X-ray fluorescence analysis; FIG. 4 is a diagram showing measurement results of fluorescent X-ray spectra before BG removal processing; FIG. 10 is a diagram showing measurement results of BG fluorescence X-ray spectra used for BG removal processing; FIG. 10 is a diagram showing measurement results of fluorescent X-ray spectra after BG removal processing; 6A-C and 7A-C are flow charts illustrating the measurement process; It is a diagram showing the same measurement example of transmission XAS and fluorescence XAS, showing an embodiment of the present invention, showing a case of measuring Cu. 1 is a configuration block diagram of transmission and fluorescence XAS systems used in conventionally known high intensity synchrotron radiation facilities; FIG.

First, technical terms used in this specification are defined.
The transmission configuration is a configuration in which X-rays are irradiated to a measurement sample, absorption is estimated by comparing the intensity of the incident X-rays and transmitted X-rays, and the X-ray absorption spectrum is obtained by plotting against the energy of the incident X-rays. say.
Fluorescence configuration is to irradiate a measurement sample with X-rays, estimate pseudo absorption by comparing the intensity of incident X-rays and fluorescence X-rays generated by absorption of X-rays, and plot against the energy of incident X-rays. It refers to the arrangement for obtaining an X-ray absorption spectrum.
X-ray X-ray is a method of irradiating a sample to be measured with X-rays, estimating absorption by comparing the intensity of incident X-rays and transmitted X-rays, and plotting against the energy of incident X-rays to obtain an X-ray absorption spectrum. Refers to absorption spectroscopy (XAS).
Fluorescence XAS involves irradiating X-rays onto a measurement sample, estimating pseudo absorption by comparing the intensity of incident X-rays and the intensity of fluorescent X-rays generated by absorption of the X-rays, and plotting against the energy of the incident X-rays. X-ray absorption spectroscopy (XAS) to obtain an X-ray absorption spectrum.

Next, the present invention will be described with reference to the drawings.
FIG. 1 is an overall block diagram of an X-ray spectrometer, showing an embodiment of the present invention.
The X-ray spectrometer of the present invention comprises an X-ray light source 100, X-ray collecting mirrors 110a and 110b, an analyzing crystal 120, a rotating table 130, a motor 140, an encoder 150, a slit 160 and an aperture 170. Motor 140 and encoder 150 are positioned below rotary table 130 .
It also has a fluorescence spectroscopic device 400, a spatially resolved X-ray detector 410, and a PC (personal computer) 420 as detectors and arithmetic devices. The Si detector as the spatially resolving X-ray detection device 410 includes a Si detector light receiving section 410a and a Si detector conversion section 410b. There are also excitation X-rays 300a, 300b, a fluorescence reference gas 210, and a measurement object 200. FIG.

The X-ray light source 100 is a broadband X-ray source whose target is tungsten, rhodium, etc., and emits light in the X-ray region of several keV to several tens of keV (optical conversion wavelength: 0.12 nm to 0.6 nm). The X-ray source 100 generally comprises a sealed vacuum chamber or a vacuum environment (typically greater than 10 ⁻⁶ Torr) maintained by active pumping, with wires connected to a high voltage power supply outside the vacuum chamber. It has X-ray source 100 comprises an electron emitter that produces an electron beam, a target that the electron beam impinges on, and an electrostatic lens system for adjusting the dose and voltage of the electron beam provided by the electron emitter. An electrostatic lens system can scan, focus or defocus the electron beam onto a target comprising an x-ray generating structure.
X-rays from the X-ray source 100 have an energy bandwidth higher than and including the energy corresponding to the absorption edge of the element to be detected. This energy bandwidth is determined, for example, so that characteristic X-rays corresponding to Lα, Lβ, Kα, Kβ, etc. of the element to be detected can be identified in the X-ray fluorescence spectrum and X-ray absorption spectrum.

The X-ray condensing optical system acts as an X-ray condensing lens and is composed of X-ray condensing mirrors 110 a and 110 b, analyzing crystal 120 , slit 160 and aperture 170 .
X-ray collector mirrors 110a, 110b have reflective surfaces corresponding to one or more portions of a quadratic function such as toroidal mirrors, polycrystalline mirrors, Walter mirrors (e.g., parabolic and hyperbolic shapes). A line capillary lens can be included. X-ray collector mirrors 110a, 110b include, but are not limited to, X-ray optical lens arrays based on total external reflection. For X-rays incident on the surface of a material with atomic number Z at an angle θ, the reflectance is nearly 100% near the grazing angle (e.g., θ≈0°), a material- and X-ray energy-dependent critical It decreases for angles greater than angle θc. The critical angle is usually less than 2° and thus limits the angle acceptance of most x-ray optical systems.

The analyzing crystal 120 disperses broadband X-rays in a certain direction, and uses a crystal optical element such as Ge, Si, or highly oriented pyrolytic graphite (HOPG). The selection of the analyzing crystal for the wavelength to be spectroscopic depends on the following Bragg's equation, where 0<λ<2d.
2d·sin θ=nλ (1)
Here, d is the distance between crystal planes, θ is the incident angle of X-rays, and λ is the wavelength of the incident X-rays. n is an integer and indicates the order of reflection. When n=1, it represents first order reflection.
As the wavelength λ to be spectroscopy increases, the 2d value of the dispersing crystal must also increase. When the incident angle of X-rays is changed, strong reflection occurs when the incident angle satisfies the formula (1).
An analyzing crystal 120 is arranged on the rotary table 130, and gives a dispersion angle to the analyzing crystal 120 according to the angle. A motor 140 is a power source for the rotary table 130 . Encoder 150 is used for angular positioning of analyzing crystal 120 by reading and indicating the rotation angle of rotary table 130 .
The excitation X-rays 300 a are X-rays emitted from the X-ray light source 100 before the object 200 to be measured is irradiated. The excitation X-rays 300 b are X-rays that have been spectroscopically separated by the analyzing crystal 120 .

The slit 160 and the aperture 170 focus some of the X-rays collected by the X-ray collecting mirrors 110a, 110b and the analyzing crystal 120 to a focused spot on the measurement object 200 having a focused size of less than 500 μm. configured to allow
The slit 160 cuts out, from the X-rays 300b dispersed by the analyzing crystal 120, an X-ray monochromatic light having an energy bandwidth higher than and including the energy corresponding to the absorption edge of the element to be detected. and the resolution preferably has an energy resolution higher than 3 eV.
Aperture 170 reduces stray light and scattered light so that X-rays other than measurement object 200 are not irradiated, and a filter for cutting higher-order light may be attached. Aperture 170 is typically a small hole having a diameter corresponding to the size of the focused spot produced by the X-ray optical lens train, and the diameter of the stop may be typically 5-25 μm. The aperture may include slits oriented generally horizontally (ie, parallel to the sagittal plane). The diaphragm element itself may comprise a piece of metal (eg molybdenum or platinum) having a thickness less than the depth of focus of the optical system (eg about 20 μm thick).

A measurement object 200 is a target sample whose substance identification and state should be investigated by absorption and/or fluorescence X-ray spectroscopy. The object 200 to be measured is placed on a support base, and the object 200 to be measured can be translated and/or rotated by moving and rotating the support base. Therefore, the X-rays that have passed through the aperture 170 can irradiate different parts of the object 200 to be measured. This allows different positions of the measurement object 200 to be illuminated or illuminated from several angles of incidence during the scan.
The movement/rotation mechanism of this support table acts as a function of adjusting the position and angle of the measurement object 200 with respect to the X-rays emitted to the measurement object 200 in the fluorescence spectrometer 400 .

The fluorescence spectrometer 400 detects X-rays irradiated and scattered by the object 200 to be measured, and is a silicon drift detector (SDD), a compact spectroscope, or the like. Fluorescence spectroscopy device 400 may be a detector element with an energy resolution higher than 150 eV. Having an energy resolution higher than 150 eV makes it possible to identify characteristic X-rays corresponding to Kα, Kβ, etc. of the atomic element to be detected in the fluorescent X-ray spectrum.

The Si detector as the spatially resolving X-ray detection device 410 detects X-rays that have passed through the measurement object 200, and has detection sensitivity in the X-ray region. It is configured including a device conversion unit 410b. The Si detector light receiving part 410a is better if it is a ^two -dimensional Si detector because it improves convenience such as sample alignment and detection area selection. good. Furthermore, the Si detector light receiving unit 410a has, for example, two-dimensionally arranged diodes with a pixel size of 25 μm or more and 1000 μm or less, has detection sensitivity in the X-ray region, can perform photon counting, and absorbs atomic elements to be detected. Any device that obtains an X-ray absorption spectrum from the measurement object 200 over an energy bandwidth including edges may be used. The Si detector conversion section 410b amplifies the received light signal of each pixel of the Si detector light receiving section 410a, and is preferably capable of photon counting according to the energy level of the received light signal.

A PC (personal computer) 420 performs signal processing, control of each device, and calculation, and includes software. The PC 420 can simultaneously perform X-ray absorption spectroscopic analysis and fluorescent X-ray analysis using the Si detector as the fluorescence spectroscopic device 400 and the spatially resolving X-ray detection device 410. can be strictly matched between X-ray absorption spectroscopy and fluorescent X-ray spectroscopy to observe the object 200 to be measured. Also, the PC 420 can observe the measurement object 200 using either the signal from the fluorescence spectroscopic device 400 or the spatially resolving X-ray detection device 410 . Furthermore, the PC 420 has a function of adjusting the slit 160 and the aperture 170 and adjusting the position and posture of the support table on which the object 200 to be measured is placed. With this function that enables X-ray irradiation to any part of the measurement object 200, the alignment (positional relationship) between the X-ray irradiation position and the fluorescence detector and/or the X-ray absorption spectrometer and the measurement object 200 can be freely adjusted. A signal of X-ray fluorescence spectrum and/or X-ray absorption spectrum can be obtained under favorable conditions.
A fixed amount of the fluorescence reference gas 210, such as Ar or Kr, is supplied as an atmosphere gas, thereby eliminating the need for a vacuum device and enabling correction of the fluorescence intensity.

In the apparatus configured as described above, the fluorescent X-rays 310 generated by irradiating the measurement object 200 are detected by the fluorescence spectrometer 400 . By using a slit 160, an aperture 170, and a high-order light cut filter in front of the object 200 to be measured, fluorescence XAS can be obtained with high energy resolution while being small and versatile. In addition, although correction of intensity is a problem in fluorescence XAS, correction can be made using the fluorescence intensity of the atmospheric gas (for example, Ar or Kr) as a reference intensity.
The X-rays 320 transmitted through the object to be measured are detected by a spatially resolving X-ray detector 410, analyzed by a PC (personal computer) 420 based on the energy level of the received light signal, and subjected to X-ray absorption spectroscopic analysis. . X-ray absorption spectrum (XAS: X-ray Absorption Spectra) or X-ray absorption fine structure (XAFS: X-ray Absorption Fine Structure) is an X-ray absorption near-edge structure (XANES) and an extensive X-ray absorption fine structure (EXAFS) There is a distinction between In the structure near the X-ray absorption edge (XANES), the information of the first energy bandwidth over the energy bandwidth of 200 eV or less on the high energy side from the absorption edge effective for analysis of the electronic state and peripheral structure of the X-ray absorption element is included. Extensive X-ray absorption fine structure (EXAFS) contains information of a second energy bandwidth over an energy bandwidth below 2 keV on the high-energy side from the absorption edge.
In XANES and EXAFS, the range to be measured is determined by the energy of the element to be measured and the accuracy with which the analysis is performed. Therefore, with XANES, in many cases, sufficient analysis can be performed by measuring the energy bandwidth of 200 eV or less on the high-energy side from the absorption edge, but there is no problem even if the measurement exceeds 200 eV. In addition, in EXAFS, in many cases, sufficient analysis can be performed by measuring up to 2 keV, but there is no problem even if it exceeds 2 keV.
Fluorescent X-rays 310 generated by irradiating the object to be measured are received by the fluorescence spectrometer 400 to obtain a fluorescent X-ray spectrum.

FIG. 2 is a flow chart illustrating the measurement process of the apparatus shown in FIG.
First, the object 200 to be measured is set at a predetermined placement position behind the aperture 170 where the fluorescent X-rays 310 by the fluorescence spectrometer 400 and the transmitted X-rays 320 by the Si detector 410 can be received. The system is adjusted (S100).
X-rays having a predetermined X-ray energy are irradiated from the X-ray light source 100 to the measurement object 200 (S110). Using the motor 140 and the encoder 150, the rotating table 130 is rotated to the analyzing crystal angle corresponding to the target X-ray energy, and the analyzing crystal 120 is angularly positioned (S120).
Then, the Si detector serving as the spatially resolving X-ray detector 410 detects an absorption signal due to transmitted X-rays, and the fluorescence spectrometer 400 detects the fluorescence of the measurement object 200 based on scattered X-rays (S130).

It is determined whether there is the next target X-ray energy (S140). If YES, the process returns to S120 to rotate the rotating table 130 to the analyzing crystal angle corresponding to the next target X-ray energy. If NO, proceed to S150.
It is determined whether the measurement of the sample is transmission XAS (S150). If YES, proceed to S160; if NO, proceed to S180.
In the case of transmission XAS, the irradiation X-ray intensity _I0 is measured when there is no measuring object 200 (S160). Then, the absorption spectrum is calculated from the obtained signal data (S170). This arithmetic expression is, for example, the following expression.
Here, the mass absorption coefficient _μM is obtained by searching the literature value "International Tables for X-ray Crystallography, Vol. 3" or by the following Victoreen equation.
μ _M =Cλ ³ -Dλ ⁴ (2)
The coefficients C and D of Victoreen's formula are listed, for example, in "Basics and Applications of XAFS", Kodansha (2017), Appendix C.
When fluorescence XAS is measured instead of transmission XAS, a pseudo absorption spectrum in the fluorescence arrangement is calculated from the obtained signal data (S180).

FIG. 3 is a diagram showing the measurement result of the fluorescent X-ray spectrum, showing one embodiment of the present invention, and shows the case where the excitation light is fixed. The object to be measured is MnCr steel, and Kα of Fe has a peak near 6.4 keV, and Kβ has a peak near 7.0 keV. The Kα of Cr has a peak around 5.4 keV, and the Kα of Mn has a peak around 5.8 keV. Ar, which is the atmosphere gas, has a peak around 3 keV. Kα of Ge has a peak around 9.9 keV, and Kβ has a peak around 11.0 keV.

FIG. 4 is a 3D view showing the measurement result of the fluorescent X-ray spectrum, showing an embodiment of the present invention, showing the case of measuring Ni by scanning the excitation light. A region of interest (ROI) is a region showing energy levels of characteristic X-rays corresponding to Kα and Kβ of Ni.
According to the measurement result of the fluorescent X-ray spectrum, it can be decomposed for each decay line (Kα, Kβ) of Ni, which is the same element. Kα and Kβ cannot be separated by absorption XAS alone.

FIG. 5 is a 2D display showing the Kα, Kβ, and background signals of Ni when scanning the excitation light in FIG. Kα of Ni has a peak around 7.47 keV, and Kβ has a peak around 8.26 keV. The K absorption edge Kab of Ni is around 8.33 keV. In addition, the value of the absorption edge of each element can be obtained, for example, from Chapter 5 [4], Nondestructive Simultaneous Measurement of Metal Components (Energy Dispersive Fluorescent X-ray Analysis method) (https://www.env.go.jp/air/report/h19-03/manual/m05_4.pdf).
For example, the absorption edges of representative elements are as follows.
2.470 keV as the K absorption edge Kab of S (sulfur),
4.964 keV as the K absorption edge Kab of Ti (titanium),
5.463 keV as the K absorption edge Kab of V (vanadium),
5.988 keV as the K absorption edge Kab of Cr (chromium),
6.536 keV as the K absorption edge Kab of Mn (manganese),
7.110 keV as the K absorption edge Kab of Fe (iron),
7.708 keV as the K absorption edge Kab of Co (cobalt),
8.330 keV as the K absorption edge Kab of Ni (nickel);
8.979 keV as the K absorption edge Kab of Cu (copper),
9.660 keV as the K absorption edge Kab of Zn (zinc),
10.336 keV as the K absorption edge Kab of Ga (gallium),
11.102 keV as the K absorption edge Kab of Ge (germanium),
12.625 keV as the K absorption edge Kab of Se (selenium),
15.200 keV as the K absorption edge Kab of Rb (rubidium),
17.996 keV as the K absorption edge Kab of Zr (zirconium),
18.984 keV as the K absorption edge Kab of Nb (niobium),
The K absorption edge Kab of Mo (molybdenum) is 20.001 keV.

FIG. 6A is a diagram showing an example of setting multiple regions of interest (ROI) and procedures in fluorescent X-ray analysis. It shows a case where there are seven regions of interest (ROI), around 5.4 keV corresponding to Kα of Cr, around 6.4 keV corresponding to Kα of Fe, and 7.4 keV corresponding to Kβ of Fe. Near 0 keV, around 7.5 keV corresponding to Kα of Ni, around 9.9 keV corresponding to Kα of Ge, around 11.0 keV corresponding to Kβ of Ge, and around 14 to 17 keV as a background signal.

FIG. 6B is a diagram for explaining the relationship of subtracting the background that matches the width of the corresponding ROI from a certain fluorescent X-ray peak in FIG. 6A. A background signal per unit X-ray energy width is subtracted as a noise signal from the X-ray energy measurement value of the predetermined region of interest to obtain the signal strength of the X-ray energy of the target region of interest.

FIG. 6C is a diagram showing another example of setting multiple regions of interest (ROI) and procedures in X-ray fluorescence analysis. A W (tungsten) electrode is used as the X-ray light source, the applied voltage is 20 kV and 200 W, the energy hv of the X-ray beam is 9050 eV, and the irradiation time is 50 seconds. where h is Planck's constant and ν is the frequency of light. The sample is an iron alloy.
FIG. 6C shows L, M, and N channels as regions of interest (ROI) when using a multi-channel analyzer as one of the detectors, for example. The L channel is a region of 6.0 to 6.75 keV containing Kα of Fe as a signal component, the M channel is a region of 6.8 to 7.4 keV containing Kβ of Fe as a signal component, and the N channel is a background signal BG. The desired BG channel is in the region of 12 to 15.8 keV here. At this time, the true count number of the region of interest (ROI1) of the L channel is obtained by dividing the count number of the fluorescent X-ray spectrum before the BG removal process into the proportional division ratio according to the bandwidth of the BG fluorescent X-ray spectrum used for the BG removal process. is the value after deducting
Further, the true count number of the region of interest (ROI2) of the M channel is obtained by dividing the count number of the fluorescent X-ray spectrum before the BG removal process into the proportional division ratio according to the bandwidth of the BG fluorescent X-ray spectrum used for the BG removal process. It is a deducted value.

FIG. 7A is a diagram showing the measurement result of the fluorescent X-ray spectrum before the BG removal process, and was measured under the same conditions as those shown in FIG. 6C.
FIG. 7B is a diagram showing measurement results of BG fluorescent X-ray spectra used for BG removal processing.
FIG. 7C is a diagram showing measurement results of fluorescent X-ray spectra after BG removal processing. The measurement result of the BG fluorescence X-ray spectrum used for the BG removal process shown in FIG. 7B is subtracted from the measurement result of the fluorescence X-ray spectrum before the BG removal process shown in FIG. 7A. For example, focusing on the count number of Kα of Fe, it is about 2100 before BG removal, about 500 with BG, and about 1600 after BG removal.

FIG. 8 is a flow chart illustrating the measurement process shown in FIGS. 6A-C and 7A-C. Here, it is assumed that the object to be measured is a sample containing a mixture of multiple elements.
First, a region of interest is set for several fluorescent X-ray peaks (S200). Next, the energy of the irradiated X-ray is scanned and the region of interest count is stored (S210). Then, the background that matches the width of each region of interest is subtracted (S220). Fluorescence XAS is obtained by fluorescence X-ray analysis of irradiation X-ray energy (S230).

FIG. 9 is a diagram showing an example of the same measurement of transmission XAS and fluorescence XAS, showing an embodiment of the present invention, showing a case of measuring Cu. The K absorption edge Kab of Cu is around 8.98 keV, and the count value increases rapidly from this energy level.

FIG. 10 is a configuration block diagram of a transmission and fluorescence XAS system used in a conventionally known high-intensity synchrotron radiation facility. Monochromatic X-rays from a synchrotron enter a sample through an ionization chamber (ion chamber) for measuring X-ray intensity. The sample is irradiated with X-rays, transmitted X-rays are detected by the ionization chamber, and fluorescent X-rays are detected by the fluorescence detector. Here, in addition to the ion chamber for measuring the incident light intensity _I0 , there is a first ion chamber for measuring the transmitted X-ray intensity of the sample, and a reference metal foil transmitted through this first ion chamber. Fig. 3 shows a measurement system with a second ion chamber for measuring X-ray intensity;

Advantages of the measurement system of the present invention compared to transmission and fluorescence XAS systems used in such previously known high intensity synchrotron radiation facilities are the following.
(A): Since the measurement system of the present invention does not use synchrotron radiation or vacuum, it is portable and consumes less power than conventional high-intensity synchrotron radiation facilities.
(B): The measurement system of the present invention does not require the vacuum ionization chamber (ion chamber) used in conventional high-intensity synchrotron radiation facilities, and is normalized by the atmospheric rare gas fluorescence intensity.
(C): In the measurement system of the present invention, it is possible to irradiate any part of the sample with X-rays by adjusting the aperture and the slit, and by adjusting the position and posture of the support table on which the sample is placed. The alignment (positional relationship) between the X-ray detector and/or the absorption X-ray detector and the X-ray irradiation position of the sample can be made flexible, and signals can be obtained under favorable conditions.
(D): In the measurement system of the present invention, in combination with a two-dimensional detector, adjustments can be made while confirming the irradiated sample image or the irradiated position.
(E): According to the measurement system of the present invention, the absorption edge can be determined more accurately from the comparison of transmission XAS and fluorescence XAS as shown in FIG. Information such as the presence or absence of self-absorption and sample thickness effects can be obtained by comparison.
(F): In transmission XAS, measurement is not possible when the amount of the element to be measured is small, when the concentration of the element to be measured is low, and when the measurement sample is supported on a thick substrate that makes it difficult for X-rays to pass through. Although it is difficult, if the transmission XAS is difficult to measure, the fluorescence XAS can be used for the measurement.

In the above embodiment of the present invention, the first X-ray collecting mirror 110a installed on the side of the X-ray light source serves as the X-ray collecting lens, and the light reflected by the first X-ray collecting mirror A case has been shown in which the X-rays are incident on the analyzing crystal 120, the second X-ray collecting mirror 110b on which the X-rays dispersed by the analyzing crystal are incident, the slit 160 and the aperture 170, but the present invention is this. is not limited to For example, other X-ray optical systems such as Walter type I optical lenses, conical capillary lenses, polycapillary lenses, Kirkpatrick-Baez lenses, Montel lenses can be used as components of the optical lens train. Systems including filters and additional beam stops etc. can also be used. In addition, other X-ray optical elements such as Fresnel zone plates, cylindrical Wolter optical lenses, Wolter type II or III optical lenses, Schwarzschild optical lenses, diffraction gratings, crystal mirrors using Bragg diffraction, hole array lenses. , multiprism or "alligator" lenses, rolled x-ray prism lenses, "lobster eye" optical lenses, microchannel plate optical lenses, or in combination with those described above, certain Compound optical systems of embodiments of the present invention can be formed that direct X-rays in a manner.

In addition, in the above-described embodiment of the present invention, the case of the Si detector having the Si detector light receiving section 410a and the Si detector conversion section 410b was shown as the spatially resolved X-ray detection device. known in the art, including, but not limited to, CCD arrays (X-ray sensors), CMOS or S-CMOS detectors, flat panel sensors, or 1D linear detectors and 2D array detectors. There may be one or more position sensitive x-ray array detectors that convert x-ray intensity into electronic signals. Examples of position-sensitive detectors include linear detectors, position-sensitive array detectors, PIN diodes, proportional counters, spectrometers, photodiode detectors, scintillator-type and gas-filled array detectors, and the like. In some embodiments, any type of detector for detecting X-rays can be included, including proportional detectors and avalanche detectors or energy dispersive elements.
Further, in the above-described embodiment of the present invention, a case was shown in which an accurate absorption process can be observed by performing X-ray absorption spectroscopy and fluorescent X-ray spectroscopy of an object at the same time. is not limited to static measurements, but dynamic change processes can be observed by performing, for example, in situ measurements or operand measurements.

According to the method and system for simultaneously performing X-ray absorption spectroscopy and X-ray fluorescence spectroscopy of the present invention, information that cannot be seen with conventional transmission types alone (for example, dynamics of absorption and fluorescence) can be obtained for various substances. elucidation) can be obtained, for example, it can be used to observe changes in proteins and organisms at the molecular level.
In addition, according to the method and system for simultaneously performing X-ray absorption spectroscopy and X-ray fluorescence spectroscopy of the present invention, signals can be obtained even from thick samples and low-density materials that cannot be handled by the "transmission type", so observation A wide range of possible sample geometries is allowed.

100 X-ray light source 110a, 110b X-ray collecting mirror 120 Analysis crystal 130 Rotating table 140 Motor 150 Encoder 160 Slit 170 Aperture 200 Measurement object 210 Fluorescence reference gas 300a Excitation X-ray 300b Excitation X-ray (after spectroscopy)
310 Fluorescent X-ray 320 Transmitted X-ray 400 Fluorescence spectrometer 410 Spatial-resolved X-ray detector (Si detector)
410a Si detector light receiving unit 410b Si detector conversion unit 420 PC (arithmetic unit)
EXAFS Extended X-ray absorption fine structure XANES X-ray absorption near-edge structure XAS X-ray absorption spectroscopy XRF X-ray fluorescence spectroscopy

Claims (10)

A method for simultaneously performing X-ray absorption spectroscopy in transmission geometry and X-ray fluorescence spectroscopy in fluorescence geometry, comprising:
irradiating the object with an X-ray beam having an energy bandwidth higher than and including the energy corresponding to the absorption edge of the element;
acquiring an x-ray absorption spectrum from the object over an energy bandwidth including the absorption edge with an energy resolution greater than 3 eV using a spatially resolving x-ray detector;
Acquiring a fluorescent X-ray spectrum by detecting X-rays scattered from the object using a fluorescent X-ray detection device;
How to prepare. The X-ray absorption spectrum obtained from the object using the spatially resolved X-ray detection device is
Information on a first energy bandwidth for obtaining an X-ray absorption edge near-edge structure over an energy bandwidth of 200 eV or less on the high energy side from the absorption edge;
second energy bandwidth information for obtaining an extended X-ray absorption fine structure over an energy bandwidth of 2 keV or less on the high energy side from the absorption edge;
2. The method of claim 1, comprising at least one of: The fluorescent X-ray spectrum is
For the spectral intensity of a region of interest in the energy bandwidth containing the absorption edge of the element,
The spectral intensity of the energy bandwidth of the background region, which is an energy bandwidth outside the region of interest and does not include the absorption edge of the element, is averaged in the energy bandwidth of the background region, and noise is obtained. Let the spectral intensity be
subtracting the noise spectral intensity from the spectral intensity of the region of interest to obtain the true measured spectral intensity of the region of interest;
The method of claim 1. The spectral intensity of the region of interest (ROI) of the energy bandwidth including the absorption edge of the element is determined from the count number of the X-rays detected by the fluorescent X-ray detection device,
The true value of the count number of the X-rays is the bandwidth of the noise spectrum fluorescence X-ray spectrum used for the subtraction process of the noise spectrum intensity from the count number of the fluorescence X-ray spectrum before the noise spectrum intensity is subtracted. A formula with a value after deducting the corresponding proportional division ratio (BW/BW _BG ):
4. The method of claim 3, wherein the method is computed by:
Here, True ROI counts is the true value of the number of X-ray counts, Raw ROI counts is the count number of fluorescent X-ray spectra before noise spectrum intensity is subtracted, ROI _BG counts is the noise spectrum intensity, and BW is the region of interest. , BW _BG is the energy bandwidth of the background region. A system for simultaneously performing X-ray absorption spectroscopy in transmission configuration and X-ray fluorescence spectroscopy in fluorescence configuration, comprising:
an X-ray light source;
An X-ray absorption edge vicinity structure over an energy bandwidth of 200 eV or less on the high energy side from the absorption edge corresponding to the absorption edge of the element contained in the object from the X-ray light source, or high from the absorption edge at least one X-ray collecting lens configured to emit X-rays having an energy bandwidth suitable for measurements to obtain an extended X-ray absorption fine structure over an energy bandwidth of 2 keV or less on the energy side;
a support configured to support the object to be measured;
The energy bandwidth includes the X-ray energy corresponding to the absorption edge, and the at least one X-ray collecting lens directs at least a portion of the X-rays to the object having a collection size of less than 500 μm. configured to focus light onto the measurement spot above,
at least one spatially resolved X-ray detection device configured to detect X-rays transmitted through the object;
at least one fluorescent X-ray detector configured to detect X-rays scattered from the object;
The X-ray condensing lens includes a first X-ray condensing mirror installed on the X-ray light source side, an analyzing crystal into which the X-rays reflected by the first X-ray condensing mirror are incident, and the analyzing crystal. A system consisting of a second X-ray collection mirror, a slit and an aperture into which the spectroscopic X-rays are incident. 6. The system according to claim 5, wherein said spatially resolving X-ray detection device is a detection element having a two-dimensional arrangement of diodes with a pixel size of 25 μm or more and 1000 μm or less, having detection sensitivity in the X-ray region, and having a photon counting function. . 6. The system according to claim 5, wherein said fluorescent X-ray detector is a detector element having an energy resolution higher than 150 eV. 6. The system according to claim 5, wherein said fluorescent X-ray detector has a function of adjusting the position and angle of said object with respect to X-rays emitted to said object. The system has an arithmetic unit that processes detection signals from the fluorescent X-ray detector,
When obtaining the X-ray fluorescence spectrum, the computing device determines the spectral intensity of the region of interest of the energy bandwidth including the absorption edge of the element, the energy bandwidth outside the region of interest, and the absorption of the element. For the spectral intensity of the energy bandwidth of the background region not including the edge, find the average value in the energy bandwidth of the background region and use it as the noise spectral intensity,
subtracting the noise spectral intensity from the spectral intensity of the region of interest to obtain the true measured spectral intensity of the region of interest;
6. The system of claim 5. The spectral intensity of the region of interest (ROI) of the energy bandwidth including the absorption edge of the element is determined from the count number of the X-rays detected by the fluorescent X-ray detection device,
The true value of the count number of the X-rays is the bandwidth of the noise spectrum fluorescence X-ray spectrum used for the subtraction process of the noise spectrum intensity from the count number of the fluorescence X-ray spectrum before the noise spectrum intensity is subtracted. A formula with a value after deducting the corresponding proportional division ratio (BW/BW _BG ):
10. The system of claim 9, operated by:
Here, True ROI counts is the true value of the number of X-ray counts, Raw ROI counts is the count number of fluorescent X-ray spectra before noise spectrum intensity is subtracted, ROI _BG counts is the noise spectrum intensity, and BW is the region of interest. , BW _BG is the energy bandwidth of the background region.