JP7726044B2 - X-ray spectrometer and elemental analysis method - Google Patents

Description

This disclosure relates to an X-ray spectrometer and an elemental analysis method.

X-ray spectrometers are known as devices that disperse characteristic X-rays (fluorescent X-rays) emitted by a sample irradiated with excitation rays such as primary X-rays or electron beams, and detect the intensity of each wavelength. International Publication No. 2018/053272 (Patent Document 1) describes such an X-ray spectrometer in which a curved dispersing crystal and detector are arranged along the circumference of a single Rowland circle. The X-ray spectrometer described in Patent Document 1 focuses and simultaneously disperses characteristic X-rays from a light source positioned inside the Rowland circle using a curved dispersing crystal, which then detects the X-rays using a detector.

International Publication No. 2018/053272

However, in the X-ray spectrometer described in Patent Document 1, when a group of characteristic X-rays with different peak wavelengths is dispersed using a dispersing element such as a curved dispersing crystal, no consideration is given to the spectroscopic range of the dispersing element in which each of the characteristic X-rays of the group of characteristic X-rays should be dispersed. If the spectroscopic range is set to cover all peak wavelengths of the group of characteristic X-rays, the length along the Rowland circle of the spectroscopic surface of the dispersing element becomes large. When this length becomes large, the difference in the radius of curvature between the Rowland circle and the dispersing element causes a problem in that the detection accuracy of the characteristic X-rays by the detector decreases in areas of the dispersing element that are far from the Rowland circle.

This disclosure has been made in consideration of these circumstances, and one of its objectives is to provide an X-ray spectrometer capable of detecting characteristic X-rays with high accuracy using a detector.

An X-ray spectroscopic analysis apparatus according to one aspect of the present disclosure includes an excitation source, a curved dispersing element, a position-sensitive detector, and a calculation unit. The excitation source irradiates an excitation beam onto a sample held in a sample holder, generating a group of characteristic X-rays with different peak wavelengths. The curved dispersing element disperses the group of characteristic X-rays. The position-sensitive detector detects at least a portion of the group of characteristic X-rays dispersed by the dispersing element. The calculation unit analyzes the elements contained in the sample based on the detection results of the detector. The dispersing element and detector are arranged along the circumference of a single Rowland circle. The length of the dispersing surface of the dispersing element along the Rowland circle is shorter than the length of the irradiation surface of the excitation beam irradiated onto the sample holder within the plane of the Rowland circle. The dispersing element and sample holder are arranged so that the group of characteristic X-rays is dispersed within the common spectroscopic range of the dispersing element.

An elemental analysis method according to another aspect of the present disclosure includes the steps of irradiating an excitation ray onto a sample held in a sample holder to generate a group of characteristic X-rays having different peak wavelengths; directing the generated group of characteristic X-rays into a curved spectroscopic element, which disperses the incident group of characteristic X-rays, and causing a position-sensitive detector to detect at least a portion of the dispersed group of characteristic X-rays; and analyzing the elements contained in the sample based on the detection results of the detector, wherein the spectroscopic element and the detector are arranged along the circumference of a single Rowland circle, the length of the spectroscopic surface of the spectroscopic element along the Rowland circle is shorter than the length of the irradiation surface of the excitation ray irradiated onto the sample holder within the plane of the Rowland circle, and the spectroscopic element and sample holder are arranged so that the group of characteristic X-rays is dispersed within the common spectroscopic range of the spectroscopic element.

According to the present disclosure, the effective spectral range of the curved dispersing element can be limited to the area tangent to the circumference of the Rowland circle, preventing a decrease in the detection accuracy of characteristic X-rays due to differences in the radii of curvature between the Rowland circle and the dispersing element. This allows the detector to detect fluorescent X-rays with high accuracy.

1 is a diagram schematically illustrating the overall configuration of an X-ray spectroscopic analysis device. FIG. 1 is a diagram showing the relationship between an X-ray spectroscopic analyzer and Rowland circles. FIG. 10 is a diagram illustrating an example of a curved light-splitting element. FIG. 10 is a diagram showing the simulation results of a projected image of the Co Kα1 ray as viewed from the light receiving surface of the detector. FIG. 10 is a diagram showing the simulation results of a projected image of the Co Kα1 ray as viewed from the light receiving surface of the detector. FIG. 10 is a diagram showing analysis results based on the detection results of a detector. FIG. 10 is a diagram showing analysis results based on the detection results of a detector. FIG. 10 is a diagram showing analysis results based on the detection results of a detector. FIG. 10 is a diagram illustrating an example of a collimator. FIG. 10 is a diagram illustrating an example of a collimator. FIG. 10 is a diagram showing the relationship between an X-ray spectroscopic analysis apparatus according to Modification 1 and Rowland's circle. FIG. 10 is a diagram showing the relationship between an X-ray spectroscopic analysis apparatus according to Modification 2 and Rowland's circle. FIG. 10 is a diagram showing the relationship between an X-ray spectroscopic analysis apparatus according to Modification 3 and Rowland's circle. FIG. 10 is a diagram showing a sample holder and a rotation mechanism according to a fourth modified example.

Each embodiment will be described in detail below with reference to the drawings. Note that identical or equivalent parts in the drawings will be given the same reference numerals and their descriptions will not be repeated.

[X-ray spectrometer 10]
FIG. 1 is a diagram showing a schematic overall configuration of an X-ray spectrometer 10. As shown in FIG.

As shown in FIG. 1, the X-ray spectrometer 10 includes an X-ray tube 11 as an excitation source, a curved spectroscopic element 12, a position-sensitive detector 14, and a calculation unit 15.

The calculation unit 15 is configured to control the operation of the X-ray spectrometer 10 and to analyze the elements contained in the sample based on the detection results of the detector 14. The calculation unit 15 is composed of a processor, memory, etc. These components are connected to each other via a bus so that they can communicate with each other.

The processor is typically an arithmetic processing unit such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit). The processor controls the operation of each part of the X-ray spectrometer 10 by reading and executing programs stored in memory. The memory is realized by non-volatile memory such as RAM (Random Access Memory), ROM (Read Only Memory), and flash memory. The memory stores programs executed by the processor, data used by the processor, etc.

The X-ray tube 11 irradiates the sample held in the sample holder 108 with excitation X-rays (also simply referred to as "excitation rays"), generating a group of characteristic X-rays (multiple characteristic X-rays with different wavelength ranges) with different peak wavelengths. Specifically, the sample holder 108 has a rectangular irradiation surface 108a with a side length of L2. The irradiation surface 108a is the opening of the sample holder 108, and the excitation rays are irradiated onto the entire irradiation surface 108a. Because the sample is held entirely within this irradiation surface 108a, a group of characteristic X-rays is generated from the irradiation surface 108a.

The curved spectroscopic element 12 disperses the characteristic X-rays from the irradiation surface 108a. The position-sensitive detector 14 detects at least a portion of the characteristic X-rays dispersed by the spectroscopic element 12. Hereinafter, in this embodiment, the characteristic X-rays generated by excitation with X-rays are also referred to as "fluorescent X-rays."

The position-sensitive detector 14 may be a one-dimensional detector. The one-dimensional detector is, for example, a silicon strip detector. By using a one-dimensional detector as the position-sensitive detector 14, it is expected that the cost of the device will be lower than that of two-dimensional detectors such as CCD (Charge Coupled Device) cameras and CMOS (Complementary Metal Oxide Semiconductor) cameras. In addition, it eliminates the need to reconstruct two-dimensional data into one dimension.

The calculation unit 15 controls the X-ray tube 11 to emit excitation rays and acquires the detection results of the characteristic X-ray group detected by the detector 14 to analyze the elements contained in the sample. This allows the valence (average valence) of the elements in the sample to be analyzed. In valence analysis, the elements contained in the sample and the valence of the elements are known, and a standard curve (e.g., a linear function representing the relationship between energy and valence) showing the peak energy versus valence is created based on the peak energies of the characteristic X-rays (respective peak energies of the characteristic X-ray group) emitted from multiple standard samples with different valences. The valence value is obtained by measuring the sample using the X-ray spectrometer 10 and applying the energy values of each of the characteristic X-ray group obtained based on the detection results of the detector 14 to the standard curve. The X-ray spectrometer 10 may also include a rotation mechanism 110. The calculation unit 15 can control the rotation mechanism 110 to rotate the sample holder 108. The rotation mechanism 110 will be described later using FIG. 10 .

Here, L2 is the length of the irradiation surface 108a of the excitation beam irradiated onto the sample holder 108 within the plane of the Rowland circle 104 (Figure 2). L1 is the length of the spectroscopic surface of the spectroscopic element 12 along the Rowland circle 104. In this embodiment, the spectroscopic element 12 and the detector 14 are arranged along the circumference of one Rowland circle 104. A specific explanation will be given below using Figure 2.

Figure 2 shows the relationship between the X-ray spectrometer 10 and the Rowland circle 104. As shown in Figure 2, the sample holder 108 and X-ray tube 11 are arranged within the Rowland circle 104, which has a radius R. The spectroscopic surface of the spectroscopic element 12 is shaped and positioned along the circumference of the Rowland circle 104. In this embodiment, the detector 14 is positioned so that its detection surface intersects the circumference of the Rowland circle 104 at two points (focal points 134 and 138 in Figure 2) rather than tangent to a single point. Generally, the X-ray spectrometer 10 may need to detect X-rays of multiple energies emitted from a single element (e.g., Kα and Kβ rays) or X-rays of different energies emitted from multiple elements (e.g., Kα rays from Mn and Kα rays from Ni). Arranging the detector 14 as in this embodiment satisfies this requirement. In this manner, the X-ray spectrometer 10 can detect X-rays of different energies with high resolution. However, the spectroscopic element 12 and detector 14 may have shapes and arrangements different from those described above as long as the effects of the present invention are achieved.

First, excitation X-rays from the X-ray tube 11 irradiate the sample holder 108 within the irradiation surface 108a, generating fluorescent X-rays specific to the elements contained in the sample. Next, the fluorescent X-rays generated from the sample are Bragg-reflected by the dispersing element (dispersing crystal) 12 arranged along the circumference of the Rowland circle 104 and are detected by the detector 14 arranged so that its surface intersects the Rowland circle 104 at two points (foci 134, 138). It is desirable to arrange the sample holder 108 so that the irradiation surface 108a is perpendicular to the direction of incidence of the characteristic X-rays incident on the dispersing element 12 from the irradiation surface 108a. In this embodiment, L2 refers to the length when the irradiation surface 108a is perpendicular. The detector 14 may also be arranged along the circumference of the Rowland circle 104.

The sample can be any material containing a metal material that generates characteristic X-rays when irradiated with excitation rays, such as a battery or a catalyst. For example, the sample may contain the three elements Mn (manganese), Co (cobalt), and Ni (nickel). In a specific example, the sample may be a lithium-ion battery (LIB) containing Li(Mn _1/3 Co _1/3 Ni _1/3 )O ₂ as the positive electrode material. The sample may also contain Fe (iron).

In this case, first, fluorescent X-rays having a first peak wavelength (also referred to as the "first wavelength range") generated from Mn, one of the contained elements, emit from a first range 140 on the sample surface. The components reach the spectroscopic range 173 of the spectroscopic element 12 and are Bragg-reflected, pass through the ranges indicated by optical paths 116 and 118, and are focused at a focal point 138 on the Rowland circle 104.

Here, the virtual focus on the Rowland circle formed by connecting the first range 140 and the spectral range 173 is indicated by focus 128. Geometrically, it can be considered that fluorescent X-rays are emitted from focus 128 (the range indicated by optical paths 125 and 127), pass through the range indicated by optical paths 116 and 118, and are then focused at focus 138.

Furthermore, the fluorescent X-rays having a second peak wavelength (also referred to as the "second wavelength range") generated from Co emit components from a second range 142 on the sample surface, reach the spectroscopic range 173 of the spectroscopic element 12, undergo Bragg reflection, pass through the range indicated by optical paths 120 and 122, and are focused at the focus 136 on the Rowland circle.

Here, the virtual focus on the Rowland circle formed by connecting the second range 142 and the spectral range 173 is indicated by focus 130. Geometrically, it can be considered that fluorescent X-rays are emitted from focus 130 (the range indicated by optical paths 121 and 123), pass through the range indicated by optical paths 120 and 122, and are then focused at focus 136.

Furthermore, the fluorescent X-rays having a third peak wavelength (also referred to as the "third wavelength range") generated from Ni, the components emitted from the third range 144 on the sample surface, reach the spectroscopic range 173 of the spectroscopic element 12, undergo Bragg reflection, pass through the ranges indicated by optical paths 124 and 126, and are focused at the focal point 134 on the Rowland circle.

Here, the virtual focus on the Rowland circle formed by connecting the third range 144 and the spectral range 173 is indicated by focus 132. Geometrically, it can be considered that fluorescent X-rays are emitted from focus 132 (the range indicated by optical paths 117 and 119), pass through the range indicated by optical paths 124 and 126, and are then focused at focus 134.

In this way, the characteristic X-rays (fluorescent X-rays) contain a group of characteristic X-rays (multiple characteristic X-rays with different wavelength ranges; in this case, characteristic X-rays generated by Mn, Co, and Ni) with different peak wavelengths. In this embodiment, the spectroscopic element 12 and sample holder 108 are arranged so that these characteristic X-ray groups are dispersed within the common spectroscopic range of the spectroscopic element 12.

Specifically, as explained above, the characteristic X-rays generated from Mn, Co, and Ni are all dispersed in a common spectral range, "spectral range 173." The spectroscopic element 12 and sample holder 108 are arranged so that these are dispersed in spectral range 173. In this embodiment, the spectroscopic element 12 and sample holder 108 are arranged so that the length L1 of the spectroscopic surface of the spectroscopic element 12 along the Rowland circle 104 is shorter than the length L2 of the irradiation surface of the excitation light irradiated on the sample holder 108 within the plane of the Rowland circle 104.

If the spectral ranges of the characteristic X-ray groups are not common but different, the length L1 of the spectral surface of the spectral element 12 along the Rowland circle 104 will be long. If the spectral element 12 is a Johann type, its radius of curvature will be 2R. In this case, if the size of the spectral element 12 is large relative to the Rowland circle 104 of radius R, the deviation from the Rowland circle 104 will be large at the periphery of the spectral element 12, resulting in focus deviation due to optical aberration. This will reduce the detection accuracy of the detector 14.

Furthermore, in a configuration in which the spectral ranges of the characteristic X-ray groups are completely separated from one another, if there is a defect in the crystal, the fluorescent X-rays incident on the detector 14 will be misaligned, resulting in a peak shift. This may result in incorrect evaluation of the valence. For example, in WO 2018/053272, the spectral ranges of the multiple X-rays are 171, 173, and 175, respectively (Figure 2), and are completely separated.

In this embodiment, the characteristic X-rays are dispersed only within the common spectral range 173, and the spectral range of the spectral element 12 is configured to be small relative to the size of the sample. This allows the effective spectral range 173 of the curved spectral element 12 to be limited to the vicinity of the area tangent to the circumference of the Rowland circle 104, preventing a decrease in the detection accuracy of characteristic X-rays due to differences in the radii of curvature between the Rowland circle 104 and the spectral element 12. In this way, fluorescent X-rays can be detected with high accuracy in the detector 14.

This also has the following three advantages. First, by dispersing light in a common spectral range 173, the spectral element 12 can be made more compact, thereby reducing the manufacturing cost of the spectral element 12. Second, if there is a defect in the spectral element 12, the defect can be investigated by inspecting only one element. Third, even if there is a defect in the spectral element 12, no peak shift occurs because the spectral range 173 is common.

Figure 3 shows an example of a curved dispersing element 12. In this embodiment, as shown in Figure 3, the dispersing element 12 is a doubly curved dispersing crystal.

The spectroscopic element 12 is made by attaching a thin plate 1022, which serves as the spectroscopic crystal, to a base 1020 that has been polished to a curved surface. The base is made of a metal such as SUS or low-expansion glass. Suitable materials for the spectroscopic crystal include single crystals such as Si, Ge, LiF, and quartz.

The length L1 described in Figures 1 and 2 is the length of the spectroscopic surface of the spectroscopic element 12 along the Rowland circle 104. The x direction in Figure 3 is the direction along the Rowland circle 104 and is hereinafter also referred to as the "spectroscopic direction." The y direction is the direction along the spectroscopic element 12 that is perpendicular to the x direction and is hereinafter also referred to as the "light-collecting direction."

The size of the spectroscopic element 12 is Wx in the spectroscopic direction and Wy in the focusing direction. In the example shown in Figures 1 and 2, Wx = L1. Also, Wy = L1 x 6. However, this is not limited to these values.

The concave surface of the dispersing element 12 has a curvature of radius Rx in the dispersing direction (x direction) and radius Ry in the focusing direction (y direction). The exact solution that gives the optimal curvature is expressed as Rx = 2R and Ry = 2R × sin ² _θB , where R is the radius of the Rowland circle. Here, _θB is the Bragg reflection angle determined by the lattice spacing of the dispersing crystal (dispersing element 12) and the wavelength of the incident X-rays.

A silicon strip detector (SSD) is used as the detector 14. One example of an SSD is the Mythen2, a one-dimensional semiconductor array detector manufactured by Dectris (Switzerland). Mythen2 has a pixel size of 50 μm (x direction; direction along the Rowland circle 104) x 8 mm (y direction; direction along the detector perpendicular to the x direction), and integrates 1,280 pixels (channels) in the x direction. The total field of view size is 64 mm (x direction) x 8 mm (y direction).

[Simulation results of Co Kα1 line projection image]
4A and 4B are diagrams showing the simulation results of a projected image of the Co Kα1 ray as viewed from the light receiving surface of the detector 14. FIG.

Here, the direction along the Rowland circle 104 of the irradiation surface 108a of the excitation beam irradiated onto the sample holder 108 is defined as the x direction, and the direction along the irradiation surface 108a perpendicular to the x direction is defined as the y direction. L2, as described in the example of Figure 1, is the length of the irradiation surface 108a of the sample holder 108 in the x direction. The length of the irradiation surface 108a in the y direction is also defined as L2.

Figures 4A and 4B show the results of Monte Carlo simulation (ray tracing) calculations of the image that the CoKα1 line (6.9303 keV) projects onto the detection surface of the detector, assuming that CoKα1 radiation (6.9303 keV) is emitted uniformly from the irradiation surface (irradiation surface 108a in Figure 1) of a sample measuring L2 (x direction) x L2 (y direction). The dispersing crystal (dispersing element 12) is assumed to be a Ge(220) single crystal.

Figure 4A shows the simulation results when the size of the spectroscopic element 12 is Wx = L1, Wy = L1 x 6, and Figure 4B shows the simulation results when the size of the spectroscopic element 12 is Wx = L1 x 6, Wy = L1 x 6. In this embodiment, L2 = L1 x 4.

In the case of Figure 4B, aberration tailing is observed in the x direction on the detection surface of the detector 14. On the other hand, in the case of Figure 4A, no such tailing is observed, and it can be seen that good spectral characteristics are obtained.

As such, better spectral characteristics were obtained when the x-direction size of the spectroscopic element 12 was 1/6, that is, Wx = L1 (example of Figure 4B), than when the x-direction size of the spectroscopic element 12 was Wx = L1 × 6 (example of Figure 4B).

The simulation results showed that good detection characteristics were obtained by narrowing the size Wx (= L1 = L2/4) of the spectroscopic element 12 to at least 1/2 or less, and preferably 1/4 or less, of the length L2 in the x-direction of the irradiation surface 108a of the sample holder 108.

In the present embodiment described with reference to Figures 1 and 2, L1 (the length of the spectral surface of the spectral element 12 in the spectral range along the Rowland circle 104) is also designed to be 1/2 or less of L2 (the length of the irradiation surface within the plane of the Rowland circle 104).

The fluorescent X-ray waveform of the contained elements detected by the detector 14 is processed by software to calculate its peak center energy, half-width, and peak height, any one of which values is associated with the physical properties of the sample. For example, the peak center energy is correlated with the valence electron state of the contained elements, and minute changes in the peak center energy can indicate changes in the valence state of the sample. For more details, see Reference A below.

[Reference A] K. Sato, T. Yoneda, T. Izumi, T. Omori, S. Tokuda, S. Adachi, M. Kobayashi, T. Mukai, H. Tanaka and M. Yanagida, Analytical Chemistry, Vol. 92(1), pp. 758-765, 2020.
The Kα rays, which are fluorescent X-rays of Mn, Co, and Ni, are composed of two rays, Kα1 and Kα2. The energy of Mn is 5898.7 eV for the Kα1 ray and 5887.6 eV for the Kα2 ray. The energy of Co is 6930.3 eV for the Kα1 ray and 6915.3 eV for the Kα2 ray. The energy of Ni is 7478.1 eV for the Kα1 ray and 7460.9 eV for the Kα2 ray.

Generally, due to quantum mechanical fluctuations and noise in the detection system, the measured waveforms of Kα1 and Kα2 lines are peaks with a finite width, and the bases of these peaks are detected as partially overlapping. For this reason, it is preferable to separate the peaks using curve fitting, which requires continuous acquisition of data over a specified energy range (wavelength range) that includes both lines.

A good guideline for the energy range (wavelength range) suitable for waveform analysis is at least twice, and preferably three times, the difference in energy between the Kα1 and Kα2 lines. In this embodiment, the signal from the Kα line is acquired, but this is not limiting; it may also be configured to acquire a signal from the Kβ line. In that case, the suitable energy range (wavelength range) can be calculated by replacing the Kα1 line with the Kβ1,3 line and the Kα2 line with the Kβ' line.

Figures 5A to 5C show analysis results based on the detection results of detector 14. Figure 5A shows the results for Fe, Figure 5B shows the results for Co, and Figure 5C shows the results for Ni. As shown in Figure 5A, the Kα1 and Kα2 spectral peaks of Fe are clearly detected at a predetermined position in the x-direction of detector 14. Similarly, the Kα1 and Kα2 spectral peaks of Co and Ni are clearly detected.

[Modification]
Modifications of this embodiment will be described below.

<Modification 1>
In this embodiment, as shown in FIG. 2, the common spectral range 173 is configured to be defined by the length (L1) of the spectral surface of the spectral element 12 along the Rowland circle 104.

However, this is not a limitation, and collimators (collimators 180-183) may be provided to define (set) a common spectroscopic range. The collimators are arranged on the path of the characteristic X-rays from the sample holder 108, through the spectroscopic element 12, to the detector 14.

Figures 6A and 6B are diagrams showing examples of collimators (collimators 180, 183). Figure 6A shows a single-aperture collimator 180, and Figure 6B shows a multiple-aperture collimator 183.

The single-aperture collimator 180 has one aperture 181a, as shown in Figure 6A. In contrast, the multiple-aperture collimator 183 has three apertures (apertures 184a to 184c), as shown in Figure 6B.

Figure 7 is a diagram showing the relationship between the X-ray spectrometer 10a according to Variation 1 and the Rowland circle 104. The configuration of the X-ray spectrometer 10a is basically the same as that of the X-ray spectrometer 10, except that a collimator 180 is further provided, so a detailed description will be omitted.

As shown in Figure 7, the collimator 180 is disposed on the path of the characteristic X-rays from the sample holder 108 through the spectroscopic element 12 to the detector 14. Specifically, by being disposed near the spectroscopic element 12, the common spectroscopic range 173 is narrowed by the opening 181a of the collimator 180, thereby defining the spectroscopic range.

In other words, the common spectral range 173 is defined depending on the size of the opening 181a of the collimator 180, regardless of the size of the spectral element 12.

When signal X-rays hit the edge of the spectroscopic element 12, unintended scattered rays may be generated. Therefore, by providing the collimator 180 as described above, the generation of unintended scattered rays can be prevented.

<Modification 2>
8 is a diagram showing the relationship between an X-ray spectrometer 10b according to Modification 2 and the Rowland circle 104. The configuration of the X-ray spectrometer 10b is basically the same as that of the X-ray spectrometer 10, except that collimators 181 and 182 are further provided, and therefore a detailed description thereof will be omitted. The collimators 181 and 182 are single-aperture collimators, like the collimator 180.

As shown in FIG. 8 , collimators 181 and 182 are arranged on the path of the characteristic X-ray group from the sample holder 108 to the detector 14 via the spectroscopic element 12. Specifically, collimator 181 is arranged on the path of the characteristic X-ray group from the sample holder 108 to the spectroscopic element 12, and collimator 182 is arranged on the path of the characteristic X-ray group from the spectroscopic element 12 to the detector 14, thereby defining a common spectroscopic range 173.

<Modification 3>
9 is a diagram showing the relationship between an X-ray spectrometer 10c according to Modification 3 and the Rowland circle 104. The configuration of the X-ray spectrometer 10c is basically the same as that of the X-ray spectrometer 10, except that collimators 180 and 183 are further provided, and therefore a detailed description thereof will be omitted.

As shown in Figure 9, collimators 180 and 183 are arranged on the path of the characteristic X-rays from the sample holder 108 through the spectroscopic element 12 to the detector 14. Specifically, collimator 180 is arranged near the spectroscopic element 12, and collimator 183 is arranged near the sample holder 108.

Fluorescent X-rays generated from Mn pass through opening 184a of collimator 183 (range indicated by optical paths 125 and 127), fluorescent X-rays generated from Co pass through opening 184b of collimator 183 (range indicated by optical paths 121 and 123), and fluorescent X-rays generated from Ni pass through opening 184c of collimator 183 (range indicated by optical paths 117 and 119). Furthermore, the common spectral range 173 is narrowed by opening 181a of collimator 180, defining the spectral range.

In this way, the collimator may be one that passes light rays of each wavelength range separately (collimator 183). By blocking X-rays outside the wavelength range of interest, it is possible to avoid a decrease in the signal-to-noise ratio due to scattered rays.

<Modification 4>
10 is a diagram showing a sample holder 109 and a rotation mechanism 110 according to Modification 4. In this embodiment, the X-ray spectrometer 10 includes the rotation mechanism 110. The calculation unit 15 can control the rotation mechanism 110 to rotate the sample holder 108.

In this case, the sample holder 108 and the irradiation surface 108a are configured to be rectangular. However, this is not limited to this, and a rotation mechanism 110 for rotating the circular sample holder 109 and the irradiation surface 109a may also be provided. The diameter of the irradiation surface 109a is L2.

The sample in the sample holder 109 is not necessarily held in a uniform state due to defects or uneven distribution. If the sample is in such a non-uniform state, the peak intensity calculated based on the detection results of the detector 14 will change. As described above, by rotating the sample holder 108 that holds the sample, changes in peak intensity can be avoided, and high reproducibility in the analysis results can be expected. Note that the X-ray spectrometer 10 does not necessarily have to be equipped with a rotation mechanism 110.

<Other Modifications>
The spectroscopic element 12 may be a single crystal such as Si, Ge, LiF, or quartz, or may be an artificially deposited multilayer film for soft X-rays of 2 keV or less. Alternatively, a diffraction grating having the same effect as a curved crystal may be used. The curved shape of the spectroscopic element 12 may be a Johann type or a Johansson type.

The curved shape of the light-splitting element 12 may be a spherical surface or a toroidal surface. Furthermore, other shapes, such as an ellipsoid or a paraboloid, may be used as long as the central portion is close to a sphere. The curvatures of the light-splitting direction (x direction) and the light-collecting direction (y direction) are preferably determined by Rx = 2R and Ry = 2R × sin ² θ _B , as described above, but they do not have to be strictly the same. In particular, the light-collecting direction may have the same curvature as the light-splitting direction, taking ease of manufacture into consideration.

The excitation beam may be an X-ray, an electron beam, a neutron beam, or a proton beam. The position-sensitive detector 14 may also be a two-dimensional detector such as a CCD or CMOS camera.

[Aspects]
It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

(Item 1) An X-ray spectroscopic analysis device according to one embodiment includes an excitation source, a curved dispersing element, a position-sensitive detector, and a calculation unit. The excitation source irradiates an excitation beam onto a sample held in a sample holder, generating a group of characteristic X-rays with different peak wavelengths. The curved dispersing element disperses the group of characteristic X-rays. The position-sensitive detector detects at least a portion of the group of characteristic X-rays dispersed by the dispersing element. The calculation unit analyzes the elements contained in the sample based on the detection results of the detector. The dispersing element and detector are arranged along the circumference of a single Rowland circle. The length of the dispersing surface of the dispersing element along the Rowland circle is shorter than the length of the irradiation surface of the excitation beam irradiated onto the sample holder within the plane of the Rowland circle. The dispersing element and sample holder are arranged so that the group of characteristic X-rays is dispersed within the common spectroscopic range of the dispersing element.

The X-ray spectroscopic analysis device described in paragraph 1 can limit the effective spectroscopic range of the curved dispersing element to the vicinity of the area tangent to the circumference of the Rowland circle, preventing a decrease in the detection accuracy of characteristic X-rays due to differences in the radii of curvature between the Rowland circle and the dispersing element. This allows the detector to detect fluorescent X-rays with high accuracy.

(Item 2) In the X-ray spectrometer described in item 2, the detector is positioned so that its surface intersects the Rowland circle at two points.

The X-ray spectrometer described in paragraph 2 can detect X-rays of different energies with high resolution.

(Item 3) The X-ray spectrometer described in Item 1 further includes a collimator that defines a common spectroscopic range. The collimator is disposed on the path of the characteristic X-rays from the sample holder through the spectroscopic element to the detector.

The X-ray spectroscopic analysis device described in paragraph 3 can prevent unintended scattered radiation from the edge of the spectroscopic element.

(4) In the X-ray spectrometer described in paragraph 1 or 2, the collimator has multiple openings corresponding to each of the characteristic X-ray groups.

The X-ray spectrometer described in paragraph 4 can avoid a decrease in the signal-to-noise ratio due to scattered rays by blocking characteristic X-rays outside the peak wavelength (wavelength range) of interest.

(Item 5) In the X-ray spectroscopic analysis device described in any one of Items 1 to 4, the length of the spectroscopic surface of the spectroscopic element along the circumference of the Rowland circle in the spectroscopic range is equal to or less than half the length of the irradiation surface within the plane of the Rowland circle.

The X-ray spectroscopic analysis device described in paragraph 5 can limit the effective spectral range of the curved dispersing element to the area tangent to the circumference of the Rowland circle, preventing a decrease in the detection accuracy of characteristic X-rays due to differences in the radii of curvature between the Rowland circle and the dispersing element. This allows the detector to detect fluorescent X-rays with high accuracy.

(Item 6) In the X-ray spectrometer described in items 1 to 5, the detector is a one-dimensional detector.

The X-ray spectroscopic analysis device described in paragraph 6 is expected to reduce the cost of the device. It also eliminates the need to reconstruct two-dimensional data into one dimension, as is required with two-dimensional detectors.

(Item 7) The X-ray spectrometer described in any one of Items 1 to 6 further includes a rotation mechanism for rotating the sample holder.

The analytical X-ray spectrometer described in paragraph 7 can avoid changes in peak intensity, allowing for high reproducibility of analysis results.

The elemental analysis method described in paragraph 8 includes the steps of irradiating an excitation ray onto a sample held in a sample holder to generate a group of characteristic X-rays having different peak wavelengths; directing the generated group of characteristic X-rays into a curved spectroscopic element, which disperses the incident group of characteristic X-rays, and having a position-sensitive detector detect at least a portion of the dispersed group of characteristic X-rays; and analyzing the elements contained in the sample based on the detection results of the detector, wherein the spectroscopic element and detector are arranged along the circumference of a single Rowland circle, the length of the spectroscopic surface of the spectroscopic element along the Rowland circle is shorter than the length of the irradiation surface of the excitation ray irradiated onto the sample holder within the plane of the Rowland circle, and the spectroscopic element and sample holder are arranged so that the group of characteristic X-rays is dispersed within the common spectroscopic range of the spectroscopic element.

The elemental analysis method described in paragraph 8 allows the effective spectral range of the curved dispersing element to be limited to the vicinity of the area tangent to the circumference of the Rowland circle, preventing a decrease in the detection accuracy of characteristic X-rays due to differences in the radii of curvature between the Rowland circle and the dispersing element. This allows the detector to detect fluorescent X-rays with high accuracy.

The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims, not the above description, and is intended to include all modifications that are equivalent in meaning to and within the scope of the claims.

10, 10a, 10b, 10c X-ray spectroscopic analysis device, 11 X-ray tube, 12 spectroscopic element, 14 detector, 15 calculation unit, 104 Rowland circle, 108, 109 sample holder, 108a, 109a irradiation surface, 110 rotation mechanism, 116-127 optical path, 128, 130, 132, 134, 136, 138 focus, 140 first range, 142 second range, 144 third range, 173 spectroscopic range, 180-183 collimator, 181a, 184a-184c opening, 1020 base, 1022 thin plate.

Claims (8)

an excitation source that irradiates an excitation beam onto a sample held in a sample holder to generate a group of characteristic X-rays having different peak wavelengths;
a curved spectroscopic element that disperses the characteristic X-rays;
a position-sensitive detector that detects at least a part of the characteristic X-ray group dispersed by the spectroscopic element;
a calculation unit that analyzes elements contained in the sample based on the detection results of the detector,
the spectroscopic element and the detector are arranged along the circumference of one Rowland circle,
a length of the spectroscopic surface of the spectroscopic element along the Rowland circle is shorter than a length of an irradiation surface of the excitation beam irradiated onto the sample holder within the plane of the Rowland circle;
an X-ray spectroscopic analysis device, wherein the spectroscopic element and the sample holder are arranged so as to disperse the characteristic X-rays in a common spectroscopic range of the spectroscopic element; The X-ray spectrometer according to claim 1, wherein the detector is positioned so that its surface intersects the Rowland circle at two points. a collimator defining the common spectral range;
3. The X-ray spectrometer according to claim 1, wherein the collimator is disposed on a path of the characteristic X-rays from the sample holder through the spectroscopic element to the detector. The X-ray spectrometer according to claim 3, wherein the collimator has multiple openings corresponding to each of the characteristic X-ray groups. An X-ray spectroscopic analysis device according to any one of claims 1 to 4, wherein the length of the spectroscopic surface of the spectroscopic element along the circumference of the Rowland circle in the spectroscopic range is equal to or less than half the length of the irradiation surface within the plane of the Rowland circle. An X-ray spectrometer according to any one of claims 1 to 5, wherein the detector is a one-dimensional detector. The X-ray spectrometer according to any one of claims 1 to 6, further comprising a rotation mechanism for rotating the sample holder. 1. A method for elemental analysis comprising:
irradiating an excitation beam onto a sample held in a sample holder to generate a group of characteristic X-rays having different peak wavelengths;
making the generated group of characteristic X-rays incident on a curved spectroscopic element, dispersing the incident group of characteristic X-rays by the spectroscopic element, and detecting at least a part of the dispersed group of characteristic X-rays by a position-sensitive detector;
and analyzing the elements contained in the sample based on the detection result of the detector,
the spectroscopic element and the detector are arranged along the circumference of one Rowland circle,
a length of the spectroscopic surface of the spectroscopic element along the Rowland circle is shorter than a length of an irradiation surface of the excitation beam irradiated onto the sample holder within the plane of the Rowland circle;
The method for elemental analysis, wherein the spectroscopic element and the sample holder are arranged so as to disperse the characteristic X-rays in a common spectroscopic range of the spectroscopic element.