X-ray spectrometer and elemental analysis method

Abstract

To provide an X-ray spectroscopic analysis apparatus capable of accurately detecting characteristic X-rays with a detector.SOLUTION: A spectroscopic element 12 and a detector 14 are disposed along a circumference of one Rowland circle 104. The spectroscopic element 12 has a spectral surface whose length, measured along the Rowland circle 104, is shorter than a length in a plane of the Rowland circle 104, of an irradiation surface irradiated with excitation beams emitted to a sample holder 108. The spectroscopic element 12 and the sample holder 108 are disposed to separate a group of characteristic X-rays within a common spectral range of the spectroscopic element 12.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an X-ray spectrometer and an elemental analysis method. [Background technology]

[0002] X-ray spectrometers are known as devices that disperse characteristic X-rays (fluorescent X-rays) emitted from 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 a detector are arranged along the circumference of a Rowland circle. The X-ray spectrometer described in Patent Document 1 simultaneously collects and disperses characteristic X-rays from a light source positioned inside the Rowland circle using a curved dispersing crystal, and detects the collected X-rays using a detector. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 053272 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the X-ray spectrometer described in Patent Document 1, when a group of characteristic X-rays having different peak wavelengths is dispersed using a dispersing element such as a curved dispersing crystal, no consideration is given to the dispersing 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 dispersing range is set to cover all peak wavelengths of the group of characteristic X-rays, the length along the Rowland circle of the dispersing surface of the dispersing element becomes large. If this length becomes large, a problem occurs 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 due to the difference in the radius of curvature between the Rowland circle and the dispersing element.

[0005] The present disclosure has been made in view of the above circumstances, and has an object to provide an X-ray spectrometer capable of detecting characteristic X-rays with high accuracy in a detector. [Means for solving the problem]

[0006] 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 computing unit. The excitation source irradiates an excitation beam onto a sample held in a sample holder to generate a group of characteristic X-rays having 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 computing unit analyzes elements contained in the sample based on the detection results of the detector. The dispersing element and the detector are arranged along the circumference of one 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 the sample holder are arranged so that the group of characteristic X-rays is dispersed within a common spectral range of the dispersing element.

[0007] 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 dispersing 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 elements contained in the sample based on the detection results of the detector, wherein the dispersing element and the 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 within the plane of the Rowland circle of the irradiation surface of the excitation ray irradiated onto the sample holder, and the dispersing element and the sample holder are arranged so that the group of characteristic X-rays is dispersed within a common dispersing range of the dispersing element. [Effects of the Invention]

[0008] According to the present disclosure, the effective spectral range of the curved dispersing element can be limited to the vicinity of the area tangent to the circumference of the Rowland circle, thereby preventing a decrease in the detection accuracy of characteristic X-rays due to the difference in the curvature radius between the Rowland circle and the dispersing element, thereby enabling the detector to detect fluorescent X-rays with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an outline of the overall configuration of an X-ray spectroscopic analysis device. [Figure 2] FIG. 1 is a diagram showing the relationship between an X-ray spectroscopic analyzer and Rowland's circle. [Figure 3] FIG. 10 is a diagram illustrating an example of a curved light-splitting element. [Figure 4A] FIG. 10 is a diagram showing the simulation results of a projected image of the Co Kα1 ray as seen from the light receiving surface of the detector. [Figure 4B] FIG. 10 is a diagram showing the simulation results of a projected image of the Co Kα1 ray as seen from the light receiving surface of the detector. [Figure 5A] FIG. 10 is a diagram showing analysis results based on the detection results of a detector. [Figure 5B] FIG. 10 is a diagram showing analysis results based on the detection results of a detector. [Figure 5C] FIG. 10 is a diagram showing analysis results based on the detection results of a detector. [Figure 6A] FIG. 10 is a diagram illustrating an example of a collimator. [Figure 6B] FIG. 10 is a diagram illustrating an example of a collimator. [Figure 7] FIG. 10 is a diagram showing the relationship between an X-ray spectroscopic analysis apparatus according to Modification 1 and Rowland's circle. [Figure 8] FIG. 10 is a diagram showing the relationship between an X-ray spectroscopic analysis apparatus according to Modification 2 and Rowland's circle. [Figure 9] FIG. 10 is a diagram showing the relationship between an X-ray spectroscopic analysis apparatus according to Modification 3 and Rowland's circle. [Figure 10] FIG. 10 is a diagram showing a sample holder and a rotation mechanism according to a fourth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, each embodiment will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and the description thereof will not be repeated.

[0011] [X-ray spectrometer 10] FIG. 1 is a diagram schematically showing the overall configuration of an X-ray spectrometer 10. As shown in FIG.

[0012] As shown in FIG. 1, the X-ray spectrometer 10 includes an X-ray tube 11 as an excitation source, a curved dispersing element 12, a position-sensitive detector 14, and a calculation unit 15.

[0013] 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, a memory, etc. These units are connected to each other via a bus so that they can communicate with each other.

[0014] The processor is typically an arithmetic processing unit such as a CPU (Central Processing Unit) or an 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 the memory. The memory is realized by a non-volatile memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), or a flash memory. The memory stores programs executed by the processor, data used by the processor, etc.

[0015] The X-ray tube 11 irradiates a sample held in the sample holder 108 with excitation X-rays (also simply referred to as "excitation rays") to generate a group of characteristic X-rays (plurality of characteristic X-rays with different wavelength ranges) having different peak wavelengths from one another. Specifically, the sample holder 108 has a rectangular irradiation surface 108a with a side length L2. The irradiation surface 108a is an opening of the sample holder 108, and the excitation rays are irradiated onto the entire irradiation surface 108a. Since the sample is held within the entire irradiation surface 108a, a group of characteristic X-rays is generated from the irradiation surface 108a.

[0016] The curved spectroscopic element 12 disperses the characteristic X-rays from the irradiation surface 108a. The position-sensitive detector 14 detects at least a part 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."

[0017] 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, the cost of the device can be expected to be lower than that of a two-dimensional detector such as a CCD (Charge Coupled Device) camera or a CMOS (Complementary Metal Oxide Semiconductor) camera. In addition, the effort of reconstructing two-dimensional data into one dimension is unnecessary.

[0018] The calculation unit 15 controls the X-ray tube 11 to irradiate 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 the valence analysis, the elements contained in the sample and the valences 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 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 with reference to FIG. 10.

[0019] 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 (FIG. 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 description will be given below with reference to FIG. 2.

[0020] FIG. 2 is a diagram showing the relationship between the X-ray spectrometer 10 and the Rowland circle 104. As shown in FIG. 2, the sample holder 108 and the X-ray tube 11 are arranged within the Rowland circle 104, which has a radius R. The spectroscopic surface of the spectroscopic element 12 has a shape and arrangement that follows the circumference of the Rowland circle 104. In this embodiment, the detector 14 is arranged so that its detection surface does not contact the circumference of the Rowland circle 104 at a single point but intersects with it at two points (focal points 134 and 138 in FIG. 2). 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 the detector 14 may have shapes and arrangements different from those described above as long as the effects of the present invention are achieved.

[0021] First, excitation X-rays from the X-ray tube 11 irradiate the sample holder 108 in 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 with 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 be arranged along the circumference of the Rowland circle 104.

[0022] 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 three elements: Mn (manganese), Co (cobalt), and Ni (nickel). In a specific example, the sample contains Li(Mn) as a positive electrode material. 1 / 3Co 1 / 3 Ni 1 / 3 The sample may be a lithium ion battery (LIB) containing O2. The sample may contain Fe (iron).

[0023] In this case, first, the 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, and 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.

[0024] Here, a 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 collected at focus 138.

[0025] In addition, the fluorescent X-rays having a second peak wavelength (also referred to as the "second wavelength range") generated from Co have components emitted from a second range 142 on the sample surface, which reach the spectroscopic range 173 of the spectroscopic element 12 and are Bragg-reflected, pass through the range indicated by optical paths 120 and 122, and are focused at a focus 136 on the Rowland circle.

[0026] Here, a 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 collected at focus 136.

[0027] Furthermore, the fluorescent X-rays having a third peak wavelength (also referred to as the "third wavelength range") generated from Ni have components emitted from a third range 144 on the sample surface, which reach the spectroscopic range 173 of the spectroscopic element 12 and are Bragg-reflected, pass through the ranges indicated by optical paths 124 and 126, and are focused at a focus 134 on the Rowland circle.

[0028] Here, a 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 collected at focus 134.

[0029] In this way, the characteristic X-rays (fluorescent X-rays) include a group of characteristic X-rays (plurality of characteristic X-rays with different wavelength ranges, in this case, characteristic X-rays generated respectively from Mn, Co, and Ni) with different peak wavelengths. In this embodiment, the spectroscopic element 12 and the sample holder 108 are arranged so that the group of characteristic X-rays is dispersed in a common spectroscopic range of the spectroscopic element 12.

[0030] Specifically, as explained above, the characteristic X-rays generated from any of Mn, Co, and Ni are dispersed in a common spectral range, the "spectral range 173." The spectroscopic element 12 and the sample holder 108 are arranged so that these X-rays are dispersed in the spectral range 173. In this embodiment, the spectroscopic element 12 and the 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 beam irradiated on the sample holder 108 within the plane of the Rowland circle 104.

[0031] 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 becomes long. If the spectral element 12 is a Johann type, its radius of curvature is 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 at the periphery of the spectral element 12 becomes large, resulting in defocusing due to optical aberration. This reduces the detection accuracy of the detector 14.

[0032] 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 position of the fluorescent X-rays incident on the detector 14 may be shifted, resulting in a peak shift. This may result in an inaccurate evaluation of the valence. For example, in International Publication No. 2018 / 053272, the spectral ranges of the multiple X-rays are 171, 173, and 175, respectively (Figure 2), and are completely separated.

[0033] 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 makes it possible to limit the effective spectral range 173 of the curved spectral element 12 to the vicinity of the area tangent to the circumference of the Rowland circle 104, thereby preventing a decrease in the detection accuracy of the characteristic X-rays due to the difference in the radius of curvature between the Rowland circle 104 and the spectral element 12. In this way, the detector 14 can detect fluorescent X-rays with high accuracy.

[0034] This also has the following three advantages. First, by dispersing light in a common spectral range 173, the spectroscopic element 12 can be made more compact, thereby reducing the manufacturing cost of the spectroscopic element 12. Second, if the spectroscopic element 12 has a defect, the defect can be investigated by inspecting only one element. Third, even if the spectroscopic element 12 has a defect, no peak shift occurs because the spectroscopic range 173 is common.

[0035] Fig. 3 is a diagram showing an example of a curved dispersing element 12. In this embodiment, as shown in Fig. 3, the dispersing element 12 is a doubly curved dispersing crystal.

[0036] The dispersing element 12 is fabricated by attaching a thin plate 1022 serving as a dispersing crystal to a curved, polished base 1020. The base is made of a metal such as SUS or low-expansion glass. The dispersing crystal is preferably made of a single crystal such as Si, Ge, LiF, or quartz.

[0037] 1 and 2 is the length of the spectroscopic surface of the spectroscopic element 12 along the Rowland circle 104. The x direction in FIG. 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."

[0038] The size of the light-splitting element 12 is Wx in the light-splitting direction and Wy in the light-collecting direction. In the example shown in Figures 1 and 2, Wx = L1. Also, Wy = L1 x 6. However, the values are not limited to these.

[0039] The concave surface of the light-splitting element 12 has a curvature of radius Rx in the light-splitting direction (x direction) and a curvature of radius Ry in the light-collecting direction (y direction). The exact solution that gives the optimal curvature is Rx=2R, Ry=2R×sin 2 θ B where θ B is the Bragg reflection angle determined by the lattice spacing of the dispersing crystal (dispersing element 12) and the wavelength of the incident X-ray.

[0040] The detector 14 is a Si strip detector (SSD). One example of an SSD is the one-dimensional semiconductor array detector Mythen2 manufactured by Dectris (Switzerland). Mythen2 has a pixel size of 50 μm (x direction; direction along the Rowland circle 104) × 8 mm (y direction; direction along the detector perpendicular to the x direction), and integrates 1280 pixels (channels) in the x direction. The total field of view is 64 mm (x direction) × 8 mm (y direction).

[0041] [Simulation results of the Co Kα1 line projection image] 4A and 4B are diagrams showing the simulation results of a projected image of the Kα1 line of Co as viewed from the light receiving surface of the detector 14. FIG.

[0042] 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 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.

[0043] 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 the CoKα1 line (6.9303 keV) is uniformly emitted from the irradiation surface (irradiation surface 108a in Fig. 1) of a sample with dimensions L2 (x direction) × L2 (y direction). The dispersing crystal (dispersing element 12) is assumed to be a Ge(220) single crystal.

[0044] Fig. 4A shows the simulation results when the size of the spectroscopic element 12 is Wx = L1, Wy = L1 × 6, and Fig. 4B shows the simulation results when the size of the spectroscopic element 12 is Wx = L1 × 6, Wy = L1 × 6. In this embodiment, it is assumed that L2 = L1 × 4.

[0045] In the case of Fig. 4B, a trailing aberration is observed in the x direction on the detection surface of the detector 14. On the other hand, in the case of Fig. 4A, no such trailing is observed, and it can be seen that good spectral characteristics are obtained.

[0046] As described above, better spectral characteristics were obtained when the x-direction size of the spectroscopic element 12 was Wx=L1 (example of FIG. 4B), which is 1 / 6 of the x-direction size of the spectroscopic element 12 (example of FIG. 4B), than when the x-direction size of the spectroscopic element 12 was Wx=L1×6 (example of FIG. 4B).

[0047] 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, preferably 1 / 4 or less, of the x-direction length L2 of the irradiation surface 108a of the sample holder 108.

[0048] In the present embodiment described with reference to Figures 1 and 2, L1 (the length of the spectral surface of the spectral element 12 along the Rowland circle 104 in the spectral range) 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).

[0049] The fluorescent X-ray waveform of the contained elements detected by detector 14 is processed by software to calculate its peak center energy, half-width, and peak height, and any of these values is associated with the physical properties of the sample. For example, the peak center energy correlates 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.

[0050] [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 line, which is the fluorescent X-ray of Mn, Co, and Ni, is composed of two lines: Kα1 line and Kα2 line. The energy of Mn is 5898.7 eV for Kα1 line and 5887.6 eV for Kα2. The energy of Co is 6930.3 eV for Kα1 line and 6915.3 eV for Kα2. The energy of Ni is 7478.1 eV for Kα1 line and 7460.9 eV for Kα2.

[0051] Generally, due to quantum mechanical fluctuations and noise in the detection system, the waveforms measured for Kα1 and Kα2 rays appear as peaks with a finite width, and the bases of these peaks are detected as partially overlapping. Therefore, 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 rays.

[0052] A suitable energy range (wavelength range) for waveform analysis is at least twice, and preferably three times, the difference in energy between the Kα1 and Kα2 lines. While the present embodiment is configured to acquire Kα line signals, this is not limiting and the system may be configured to acquire Kβ line signals. In this 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.

[0053] 5A to 5C are diagrams showing analysis results based on the detection results of detector 14. FIG. 5A shows the results for Fe, FIG. 5B shows the results for Co, and FIG. 5C shows the results for Ni. As shown in FIG. 5A, the Kα1 and Kα2 spectral peaks of Fe are preferably detected at predetermined positions in the x direction of detector 14. Similarly, the Kα1 and Kα2 spectral peaks of Co and Ni are preferably detected.

[0054] [Variations] Modifications of this embodiment will be described below.

[0055] <Variation 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.

[0056] However, the present invention is not limited to this, and a collimator (collimators 180 to 183) may be provided to define (set) a common spectroscopic range. The collimator is arranged on the path of the characteristic X-rays from the sample holder 108 through the spectroscopic element 12 to the detector 14.

[0057] 6A and 6B are diagrams showing examples of collimators (collimators 180, 183). Fig. 6A is a diagram showing a single-aperture collimator 180, and Fig. 6B is a diagram showing a multiple-aperture collimator 183.

[0058] As shown in Fig. 6A, the single-aperture collimator 180 has one aperture 181a. In contrast, as shown in Fig. 6B, the multiple-aperture collimator 183 has three apertures (apertures 184a to 184c).

[0059] 7 is a diagram showing the relationship between an X-ray spectrometer 10a according to Modification 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, and therefore detailed description thereof will be omitted.

[0060] 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 disposing the collimator 180 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.

[0061] That is, the common spectroscopic range 173 is defined depending on the size of the opening 181 a of the collimator 180 , without depending on the size of the spectroscopic element 12 .

[0062] Unintended scattered rays may occur when X-rays serving as signals hit the end of the spectroscopic element 12. For this reason, by providing the collimator 180 as described above, it is possible to prevent the occurrence of unintended scattered rays.

[0063] <Variation 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.

[0064] 8, collimators 181 and 182 are disposed on the path of the characteristic X-rays from the sample holder 108 through the spectroscopic element 12 to the detector 14. Specifically, collimator 181 is disposed on the path of the characteristic X-rays from the sample holder 108 to the spectroscopic element 12, and collimator 182 is disposed on the path of the characteristic X-rays from the spectroscopic element 12 to the detector 14, thereby defining a common spectroscopic range 173.

[0065] <Variation 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 detailed description thereof will be omitted.

[0066] 9, the collimators 180 and 183 are disposed on the path of the characteristic X-rays from the sample holder 108 through the spectroscopic element 12 to the detector 14. Specifically, the collimator 180 is disposed near the spectroscopic element 12, and the collimator 183 is disposed near the sample holder 108.

[0067] The fluorescent X-rays generated from Mn pass through opening 184a of collimator 183 (range indicated by optical paths 125 and 127), the fluorescent X-rays generated from Co pass through opening 184b of collimator 183 (range indicated by optical paths 121 and 123), and the 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 to define the spectral range.

[0068] In this way, the collimator may be one that passes light rays of each wavelength range separately (collimator 183). By blocking X-rays other than the wavelength range of interest, it is possible to avoid a decrease in the signal-to-noise ratio due to scattered rays.

[0069] <Variation 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.

[0070] In this case, the sample holder 108 and the irradiation surface 108a are configured to be rectangular. However, this is not limiting, and a rotation mechanism 110 for rotating the circular sample holder 109 and the irradiation surface 109a may be provided. The diameter of the irradiation surface 109a is L2.

[0071] 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 include the rotation mechanism 110.

[0072] <Other variations> 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. It may also be a diffraction grating that has the same effect as a curved crystal. The curved shape of the spectroscopic element 12 may be a Johann type or a Johansson type.

[0073] 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 in the light-splitting direction (x direction) and the light-collecting direction (y direction) are, as described above, Rx = 2R, Ry = 2R × sin 2 θ B In particular, the curvature of the light collection direction may be the same as that of the light dispersion direction, taking into consideration ease of manufacture.

[0074] The excitation beam may be an X-ray, an electron beam, a neutron beam, or a proton beam. The position-sensitive detector 14 may be a two-dimensional detector such as a CCD or CMOS camera.

[0075] [Aspect] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0076] (Item 1) An X-ray spectroscopic analysis apparatus according to one aspect 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 to generate a group of characteristic X-rays having 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 the detector are arranged along the circumference of one 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 the sample holder are arranged so that the group of characteristic X-rays is dispersed within a common spectroscopic range of the dispersing element.

[0077] According to the X-ray spectroscopic analysis device described in paragraph 1, the effective spectroscopic range of the curved dispersing element can be limited to the vicinity of the area tangent to the circumference of the Rowland circle, thereby preventing a decrease in the detection accuracy of characteristic X-rays due to the difference in the curvature radius between the Rowland circle and the dispersing element, thereby enabling the detector to detect fluorescent X-rays with high accuracy.

[0078] (Item 2) In the X-ray spectrometer described in item 2, the detector is disposed so that its surface intersects with the Rowland circle at two points.

[0079] According to the X-ray spectrometer described in item 2, X-rays of different energies can be detected with high resolution.

[0080] (Item 3) The X-ray spectrometer according to 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.

[0081] According to the X-ray spectroscopic analysis device described in the third aspect, it is possible to prevent the generation of unintended scattered rays from the end of the spectroscopic element.

[0082] (Item 4) In the X-ray spectrometer according to item 1 or 2, the collimator has a plurality of openings corresponding to the respective characteristic X-ray groups.

[0083] According to the X-ray spectrometer described in item 4, by blocking characteristic X-rays other than the peak wavelength (wavelength range) of interest, it is possible to avoid a decrease in the signal-to-noise ratio due to scattered rays.

[0084] (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 1 / 2 or less of the length of the irradiation surface within the plane of the Rowland circle.

[0085] According to the X-ray spectroscopic analysis device described in paragraph 5, the effective spectroscopic range of the curved dispersing element can be limited to the vicinity of the area tangent to the circumference of the Rowland circle, thereby preventing a decrease in the detection accuracy of characteristic X-rays due to the difference in the curvature radius between the Rowland circle and the dispersing element, thereby enabling the detector to detect fluorescent X-rays with high accuracy.

[0086] (Item 6) In the X-ray spectrometer described in items 1 to 5, the detector is a one-dimensional detector.

[0087] According to the X-ray spectroscopic analysis device described in item 6, it is expected that the cost of the device can be reduced. Also, it does not require the effort of reconstructing two-dimensional data into one dimension as with a two-dimensional detector.

[0088] (Item 7) The X-ray spectrometer according to any one of items 1 to 6 further comprises a rotation mechanism that rotates the sample holder.

[0089] According to the analytical X-ray spectrometer described in item 7, it is possible to avoid changes in peak intensity, and high reproducibility of analysis results can be expected.

[0090] 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; making the generated group of characteristic X-rays incident on a curved dispersing element, which disperses the incident group of characteristic X-rays; and causing a position-sensitive detector to detect at least a part 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 dispersing element and the detector are arranged along the circumference of one Rowland circle, the length of the dispersing surface of the dispersing element along the Rowland circle is shorter than the length within the plane of the Rowland circle of the irradiation surface of the excitation ray irradiated onto the sample holder, and the dispersing element and the sample holder are arranged so that the group of characteristic X-rays is dispersed within a common dispersing range of the dispersing element.

[0091] According to the elemental analysis method described in paragraph 8, the effective spectroscopic range of the curved dispersing element can be limited to the vicinity of the area tangent to the circumference of the Rowland circle, thereby preventing a decrease in the detection accuracy of characteristic X-rays due to the difference in the curvature radius between the Rowland circle and the dispersing element, thereby enabling the detector to detect fluorescent X-rays with high accuracy.

[0092] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0093] 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 to 127 optical path, 128, 130, 132, 134, 136, 138 focus, 140 first range, 142 second range, 144 third range, 173 spectroscopic range, 180 to 183 collimator, 181a, 184a to 184c aperture, 1020 base, 1022 thin plate.

Claims

1. 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;

2. 2. The X-ray spectrometer according to claim 1, wherein the detector is disposed so that its surface intersects with the Rowland circle at two points.

3. 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.

4. 4. The X-ray spectrometer according to claim 3, wherein the collimator has a plurality of openings corresponding to the respective characteristic X-ray groups.

5. 5. The X-ray spectroscopic analysis apparatus according to claim 1, wherein a 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 of a length of the irradiation surface within the plane of the Rowland circle.

6. 6. The X-ray spectrometer according to claim 1, wherein the detector is a one-dimensional detector.

7. 7. The X-ray spectrometer according to claim 1, further comprising a rotation mechanism for rotating the sample holder.

8. 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.

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