X-ray spectrophotometers and elemental analysis methods

Abstract

The beam splitter (12) and detector (14) are arranged along the circumference of a Rowland circle (104). The length of the beam splitter surface of the beam splitter (12) along the Rowland circle (104) is shorter than the length of the irradiation surface of the excitation rays irradiating the sample holder (108) within the plane of the Rowland circle (104). The beam splitter (12) and sample holder (108) are arranged such that the characteristic X-ray group is split through the common beam splitter range of the beam splitter (12).

Description

Technical Field

[0001] This disclosure relates to X-ray spectrophotometers and elemental analysis methods. Background Technology

[0002] X-ray spectrophotometers are known as devices that detect the intensity of characteristic X-rays (fluorescent X-rays) emitted from a sample irradiated with excitation rays such as single X-rays or electron beams by dispersing the light. International Publication No. 2018 / 053272 describes such an X-ray spectrophotometer as having a curved spectrophotometer and detector arranged along the circumference of a Rowland circle. The X-ray spectrophotometer described in International Publication No. 2018 / 053272 disperses the characteristic X-rays from a light source arranged inside the Rowland circle using a curved spectrophotometer, and then detects them using a detector. Summary of the Invention

[0003] In the X-ray spectrophotometer described in International Publication No. 2018 / 053272, when using a spectrophotometer such as a curved spectrophotometer to disperse characteristic X-ray groups with different peak wavelengths, no consideration was given to which dispersive range of the spectrophotometer should be used to disperse the characteristic X-rays of each characteristic X-ray group. If the dispersive range is set in a way that covers all peak wavelengths of the characteristic X-ray group, the length of the dispersive surface of the spectrophotometer along the Rowland circle becomes larger. If this length becomes larger, due to the difference in the radius of curvature between the Rowland circle and the spectrophotometer, a problem arises where the detection accuracy of characteristic X-rays in the detector decreases in the region of the spectrophotometer outside the Rowland circle.

[0004] This disclosure was made in view of the above-mentioned circumstances, and its purpose is to provide an X-ray spectrophotometer capable of detecting characteristic X-rays with high precision in a detector.

[0005] An X-ray spectrophotometer according to one embodiment of this disclosure includes an excitation source, a curved beam splitter, a position-sensitive detector, and a processing unit. The excitation source irradiates a sample held in a sample holder with excitation rays, generating characteristic X-ray groups with different peak wavelengths. The curved beam splitter disperses the characteristic X-ray groups. The position-sensitive detector detects at least a portion of the characteristic X-ray groups dispersed by the beam splitter. The processing unit analyzes the elements contained in the sample based on the detector's detection results. The beam splitter and detector are arranged along the circumference of a Rowland circle. The length of the beam splitting surface of the beam splitter along the Rowland circle is shorter than the length of the irradiation surface of the excitation rays irradiating the sample holder within the plane of the Rowland circle. The beam splitter and sample holder are arranged such that the characteristic X-ray groups are dispersed through a common beam splitting range of the beam splitter.

[0006] An elemental analysis method according to another aspect of this disclosure includes: irradiating a sample held in a sample holder with excitation rays to generate a set of characteristic X-rays with different peak wavelengths; incidenting the generated set of characteristic X-rays onto a curved beam-splitting element, splitting the incident set of characteristic X-rays by the beam-splitting element, and detecting at least a portion of the split set of characteristic X-rays by a position-sensitive detector; and analyzing the elements contained in the sample based on the detector's detection results. The beam-splitting element and the detector are arranged along the circumference of a Rowland circle, the length of the beam-splitting surface of the beam-splitting element along the Rowland circle being shorter than the length of the irradiation surface of the excitation rays irradiating the sample holder within the surface of the Rowland circle. The beam-splitting element and the sample holder are arranged such that the set of characteristic X-rays is split through a common beam-splitting range of the beam-splitting element.

[0007] The above and other objects, features, solutions and advantages of the present invention will be set forth in the following detailed description relating to the invention, which will be understood in conjunction with the accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a diagram that roughly shows the overall structure of an X-ray spectrophotometer.

[0009] Figure 2 This is a diagram showing the relationship between the X-ray spectrophotometer and the Rowland circle.

[0010] Figure 3 This is a diagram showing an example of a beam splitter with a curved shape.

[0011] Figure 4A , Figure 4B This is a diagram showing the simulation results of the projected image of Co's Kα1 rays as observed from the light-receiving surface of the detector.

[0012] Figures 5A-5C This is a graph showing the analysis results based on the detector's detection results.

[0013] Figure 6A , Figure 6B This is a diagram showing an example of a collimator.

[0014] Figure 7 This is a diagram showing the relationship between the X-ray spectrophotometer of Modified Example 1 and the Rowland circle.

[0015] Figure 8 This is a diagram showing the relationship between the X-ray spectrophotometer of Modified Example 2 and the Rowland circle.

[0016] Figure 9 This is a diagram showing the relationship between the X-ray spectrophotometer of Modified Example 3 and the Rowland circle.

[0017] Figure 10This is a diagram showing the specimen support and rotating mechanism of modified Example 4. Detailed Implementation

[0018] Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be labeled with the same reference numerals and their descriptions will not be repeated.

[0019] [X-ray Spectrophotometer 10]

[0020] Figure 1 This is a diagram that roughly shows the overall configuration of the X-ray spectrophotometer 10.

[0021] like Figure 1 As shown, the X-ray spectrophotometer 10 includes an X-ray tube 11 as an excitation source, a curved spectrophotometer 12, a position-sensitive detector 14, and a processing unit 15.

[0022] The arithmetic unit 15 is configured to control the operation of the X-ray spectrophotometer 10 and analyze the elements contained in the sample based on the detection results of the detector 14. The arithmetic unit 15 consists of a processor and a memory, etc. These units are interconnected via a bus.

[0023] The processor is typically a CPU (Central Processing Unit) or MPU (Microprocessor Unit). The processor controls the operation of various parts of the X-ray spectrophotometer 10 by reading and executing programs stored in memory. The memory is implemented using non-volatile memory such as RAM (Random Access Memory), ROM (Read Only Memory), and flash memory. The memory stores programs executed by the processor or data used by the processor.

[0024] X-ray tube 11 irradiates the sample held in sample holder 108 with excitation X-rays (also simply referred to as "excitation rays"), producing characteristic X-ray groups (multiple characteristic X-rays with different wavelength ranges) with different peak wavelengths. Specifically, sample holder 108 has a rectangular irradiation surface 108a with one side length L2. Irradiation surface 108a is the opening of sample holder 108, and excitation rays are irradiated onto the entire irradiation surface 108a. Since the sample is held within the entire irradiation surface 108a, characteristic X-ray groups are generated from the irradiation surface 108a.

[0025] A curved beam-splitting element 12 disperses the characteristic X-ray group from the irradiation surface 108a. A position-sensitive detector 14 detects at least a portion of the characteristic X-ray group dispersed by the beam-splitting element 12. Hereinafter, in this embodiment, the characteristic X-rays generated by X-ray excitation will also be referred to as "fluorescent X-rays".

[0026] The position-sensitive detector 14 can also be a one-dimensional detector. A one-dimensional detector is, for example, a silicon microstrip detector. By using a one-dimensional detector as the position-sensitive detector 14, compared to CCD (Charge-Coupled Device) cameras and CMOS (Complementary Metal Oxide Semiconductor) cameras, which are two-dimensional detectors, lower device costs can be expected. Furthermore, the effort of reconstructing two-dimensional data into one-dimensional data is eliminated.

[0027] The computation unit 15 controls the X-ray tube 11 to irradiate the 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 for the analysis of the valence (average valence) of the elements in the sample. In the valence analysis, the elements contained in the sample and their valences are known, and a standard curve showing the peak energy relative to the valence (e.g., a curve representing the relationship between energy and valence using a linear function) is generated based on the peak energies of the characteristic X-rays emitted from multiple standard samples with different valences (the peak energies of each characteristic X-ray group). The valence value is obtained by measuring the sample using the X-ray spectrophotometer 10 and applying the energy values ​​of each characteristic X-ray group obtained based on the detection results of the detector 14 to the standard curve. Furthermore, the X-ray spectrophotometer 10 may also include a rotation mechanism 110. The computation unit 15 can control the rotation mechanism 110 to rotate the sample holder 108. Regarding the rotation mechanism 110, using... Figure 10 To be described later.

[0028] Here, L2 is the irradiation surface 108a of the excitation rays irradiating the sample holder 108 in the Rowland circle 104 ( Figure 2 L1 is the length of the beam-splitting surface of the beam-splitting element 12 along the Rowland circle 104. In this embodiment, the beam-splitting element 12 and the detector 14 are arranged along the circumference of a Rowland circle 104. Hereinafter, the term L1 will be used... Figure 2 To explain in detail.

[0029] Figure 2 This is a diagram showing the relationship between the X-ray spectrophotometer 10 and the Rowland circle 104. (See diagram for example.) Figure 2As shown, the sample holder 108 and X-ray tube 11 are arranged within a Rowland circle 104 of radius R. The beam-splitting surface of the beam-splitting element 12 has a shape and arrangement along the circumference of the Rowland circle 104. In this embodiment, the detector 14 is configured such that its detection surface does not connect with the circumference of the Rowland circle 104 at point 1, but at point 2 (…). Figure 2 The focal points 134 and 138 intersect. Typically, in the X-ray spectrophotometer 10, there are situations where it is necessary to detect X-rays of multiple energies emitted from a single element (e.g., Kα rays and Kβ rays), and X-rays of different energies emitted from multiple elements (e.g., Kα rays from Mn and Kα rays from Ni). This requirement can be met by configuring the detector 14 as described in this embodiment. Therefore, the X-ray spectrophotometer 10 can detect X-rays of different energies with high resolution. However, the spectrophotometer 12 and detector 14 can also have different shapes and configurations than described above, within the scope of achieving the effects of this invention.

[0030] First, excitation X-rays from X-ray tube 11 irradiate the sample holder 108 within the irradiation surface 108a, generating fluorescent X-rays inherent to the elements contained in the sample. Next, the fluorescent X-rays generated from the sample undergo Bragg reflection at a spectrometer (spectral crystal) 12 arranged along the circumference of the Rowland circle 104, and are detected by a detector 14 whose surface intersects the Rowland circle 104 at two points (foci 134, 138). It is desirable that the sample holder 108 be arranged perpendicular to the incident direction of the characteristic X-rays incident from the irradiation surface 108a to the spectrometer 12; in this embodiment, L2 refers to the length when the irradiation surface 108a is set perpendicular. The detector 14 may also be arranged along the circumference of the Rowland circle 104.

[0031] The sample can be any metallic material containing an excitation ray, such as a battery or catalyst, that produces characteristic X-rays. For example, the sample can contain the elements Mn (manganese), Co (cobalt), and Ni (nickel). In a specific example, the sample can also contain Li (Mn... 1 / 3 Co 1 / 3 Ni 1 / 3 Lithium-ion batteries (LIBs) using O2 as the positive electrode material. The sample may also contain Fe (iron).

[0032] In this case, firstly, in the fluorescent X-rays having a first peak wavelength (also called the "first wavelength range") produced by Mn as one of the containing elements, the component that emits light from the first range 140 on the sample surface reaches the spectral range 173 of the spectrometer 12 and undergoes Bragg reflection, and converges to the focal point 138 on the Rowland circle 104 through the range shown by optical paths 116, 118.

[0033] Here, focal point 128 is shown as a virtual focal point on the Rowland circle that connects the first range 140 and the beam splitting range 173. Geometrically, it can be assumed that fluorescent X-rays are emitted from focal point 128 (with the ranges shown by optical paths 125, 127) and then converge at focal point 138 through the ranges shown by optical paths 116, 118.

[0034] Furthermore, in the fluorescent X-rays with a second peak wavelength (also known as the "second wavelength range") generated by Co, the component that emits light from the second range 142 on the sample surface reaches the beam splitting range 173 of the beam splitting element 12 and undergoes Bragg reflection, passing through the range shown by optical paths 120, 122, and the focal point 136 on the Rowland circle becomes the converging position.

[0035] Here, focal point 130 refers to the virtual focal point on the Rowland circle that connects the second range 142 with the beam splitting range 173. Geometrically, it can be assumed that fluorescent X-rays are emitted from focal point 130 (with the ranges shown by optical paths 121 and 123) and then converge at focal point 136 through the ranges shown by optical paths 120 and 122.

[0036] Furthermore, in the fluorescent X-rays having a third peak wavelength (also known as the "third wavelength range") generated by Ni, the component that emits light from the third range 144 on the sample surface reaches the beam splitting range 173 of the beam splitting element 12 and undergoes Bragg reflection, converging at the focal point 134 on the Rowland circle through the range shown by optical paths 124, 126.

[0037] Here, focal point 132 refers to the virtual focal point on the Rowland circle that connects the third range 144 with the beam splitting range 173. Geometrically, it can be assumed that fluorescent X-rays are emitted from focal point 132 (with the ranges shown by optical paths 117 and 119) and then converge at focal point 134 through the ranges shown by optical paths 124 and 126.

[0038] Thus, the characteristic X-rays (fluorescent X-rays) comprise groups of characteristic X-rays with different peak wavelengths (multiple characteristic X-rays with different wavelength ranges, in this case characteristic X-rays generated from Mn, Co, and Ni respectively). Furthermore, in this embodiment, a spectrometer 12 and a sample holder 108 are provided so that these groups of characteristic X-rays are dispersed through the common spectrometer range of the spectrometer 12.

[0039] Specifically, as explained above, the characteristic X-rays generated from any of Mn, Co, and Ni are also dispersed through a common dispersion range, "dispersion range 173". Furthermore, the dispersion element 12 and sample holder 108 are configured such that they are dispersed through dispersion range 173. In this embodiment, the dispersion element 12 and sample holder 108 are configured such that the length L1 of the dispersion surface of the dispersion element 12 along the Rowland circle 104 is shorter than the length L2 of the irradiation surface of the excitation rays irradiating the sample holder 108 within the plane of the Rowland circle 104.

[0040] When the beam-splitting ranges of the characteristic X-ray groups are not common but different, the length L1 of the beam-splitting surface of the beam-splitting element 12 along the Rowland circle 104 becomes longer. In the case of a John von Neumann type beam-splitting element 12, its radius of curvature is 2R. In this case, if the size of the beam-splitting element 12 is larger than the Rowland circle 104 with radius R, the offset from the Rowland circle 104 at the periphery of the beam-splitting element 12 becomes larger, resulting in a focal shift caused by optical aberrations. Consequently, the detection accuracy of the detector 14 decreases.

[0041] Furthermore, when the spectral ranges of the characteristic X-ray group are completely separated, the presence of crystal defects can cause a shift in the position of the fluorescent X-rays incident on detector 14, resulting in peak shift problems. Therefore, it may be impossible to accurately evaluate the valence. For example, in International Publication No. 2018 / 053272, the spectral ranges of multiple X-rays are 171, 173, 175 (…). Figure 2 And completely separated.

[0042] In this embodiment, the characteristic X-ray group is configured to be dispersed only through a common dispersive range 173, thus reducing the dispersive range of the dispersive element 12 relative to the sample size. This limits the effective dispersive range 173 of the curved dispersive element 12 to the region near the circumference of the Rowland circle 104, preventing a decrease in the detection accuracy of the characteristic X-rays due to the difference in curvature radii between the Rowland circle 104 and the dispersive element 12. Consequently, fluorescent X-rays can be detected with high precision in the detector 14.

[0043] Furthermore, this offers three advantages. First, by using a common beam-splitting range 173, the beam-splitting element 12 can be made more compact, reducing its manufacturing cost. Second, in the event of a defect in the beam-splitting element 12, the defect can be investigated by examining only one element. Third, even in the presence of a defect in the beam-splitting element 12, peak shift is avoided because the beam-splitting range 173 is common.

[0044] Figure 3This is a diagram illustrating an example of a beam splitter 12 with a curved shape. In this embodiment, as... Figure 3 As shown, the beam splitter 12 is a double-bend type beam splitter crystal.

[0045] The beam-dispersing element 12 is fabricated by attaching a thin plate 1022, which is a beam-dispersing crystal, to a base 1020 that has been ground into a curved surface. The base is made of a metal such as SUS or a low-expansion glass. The beam-dispersing crystal is preferably made of a single crystal such as Si, Ge, LiF, or quartz.

[0046] exist Figure 1 , Figure 2 The length L1 described herein is the length of the beam-splitting surface of the beam-splitting element 12 along the Rowland circle 104. Figure 3 The x-direction is along the direction of the Rowland circle 104, hereinafter also referred to as the "splitting direction". The y-direction is along the direction of the beam splitting element 12, which is perpendicular to the x-direction, hereinafter also referred to as the "converging direction".

[0047] The dimensions of the beam-splitting element 12 are Wx in the beam-splitting direction and Wy in the beam-converging direction. Figure 1 , Figure 2 In the example shown, Wx = L1. Furthermore, Wy = L1 × 6. However, it is not limited to these values.

[0048] The concave surface of the beam-splitting element 12 has a curvature of radius Rx in the beam-splitting direction (x-direction) and radius Riy in the converging direction (y-direction). If the radius of the Rowland circle is set to R, then the exact solution for the optimal curvature is given by Rx = 2R and Riy = 2R × sin 2 θ B Indicated by θ. B The Bragg reflection angle is determined by the lattice spacing of the spectroscopic crystal (spectral element 12) and the wavelength of the incident X-rays.

[0049] As detector 14, a Si microstrip detector (SSD) is used. As an example of an SSD, the Mythen2, a one-dimensional semiconductor array detector manufactured by Decris (Switzerland), can be used. The Mythen2 accumulates 1280 pixels (channels) in the x-direction with a pixel size of 50 μm (x-direction; along the Rowland circle 104) × 8 mm (y-direction: perpendicular to the x-direction along the detector direction). The total field of view is 64 mm (x-direction) × 8 mm (y-direction).

[0050] [Simulation results of the projected image of Co's Kα1 rays]

[0051] Figure 4A , Figure 4BThis is a diagram showing the simulation results of the projected image of Co's Kα1 rays observed from the light-receiving surface of detector 14.

[0052] Here, the direction along the Rowland circle 104 of the irradiation surface 108a of the excitation rays irradiating the sample holder 108 is defined as the x-direction, and the direction perpendicular to the x-direction along the irradiation surface 108a is defined as the y-direction. Figure 1 In the example, L2 is the length of the irradiation surface 108a in the x-direction of the sample holder 108. Furthermore, the length of the irradiation surface 108a in the y-direction is also set as L2.

[0053] exist Figure 4A , Figure 4B The diagram shows the irradiation surface of a sample assuming a size of L2 (x-direction) × L2 (y-direction). Figure 1 When the irradiation surface 108a) uniformly emits CoKα1 rays (6.9303 keV), the projection image formed by this ray on the detection surface of the detector is calculated by Monte Carlo simulation (ray tracing). The spectroscopic crystal (spectral element 12) is assumed to be a single crystal of Ge (220).

[0054] Figure 4A The simulation results are for the case where the dimensions of the beam splitter 12 are Wx = L1 and Wy = L1 × 6. Figure 4B These are simulation results for the case where the dimensions of the beam splitter 12 are Wx = L1 × 6 and Wy = L1 × 6. In this embodiment, L2 = L1 × 4.

[0055] exist Figure 4B In the case of [the aforementioned situation], a trailing effect caused by aberration is observed in the x-direction within the detection surface of detector 14. On the other hand, it is known that [the following text is incomplete and requires further context: "in the case of [the aforementioned situation], a trailing effect caused by aberration is observed in the x-direction. On the other hand, it is known that in..."] Figure 4A In such cases, such trailing is not visible, and good spectral characteristics can be obtained.

[0056] Thus, in the case where the dimension in the x-direction of the beam splitter 12 is Wx = L1 × 6 ( Figure 4B Compared to the example), in the case where the size of the beam splitter 12 in the x-direction is 1 / 6 of Wx = L1 ( Figure 4B (The example) obtained good spectroscopic characteristics.

[0057] According to the simulation results, good detection characteristics were obtained by reducing the size Wx (=L1=L2 / 4) of the beam splitter 12 to at least 1 / 2 or less, preferably 1 / 4 or less, of the length L2 in the x direction of the irradiation surface 108a in the sample holder 108.

[0058] exist Figure 1 , Figure 2In the embodiment described herein, L1 (the length of the beam-splitting surface in the beam-splitting range along the beam-splitting surface of the beam-splitting element 12 of the Rowland circle 104) is designed to be less than half of L2 (the length of the irradiation surface within the surface of the Rowland circle 104).

[0059] The fluorescent X-ray waveforms containing the element detected by detector 14 are processed by software to calculate their peak center energy, half-width at half-maximum (FWHM), and peak height, and any of these values ​​are correlated with the physical properties of the sample. For example, the peak center energy is related to the valence electron state of the element, and a small change in the peak center energy can indicate a change in the valence number of the sample. Details are provided in reference A below.

[0060] [Document 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.

[0061] In addition, the Kα rays, which are the fluorescent X-rays of Mn, Co, and Ni, consist of two rays: Kα1 and Kα2. The energy of Mn in the Kα1 ray is 5898.7 eV, and in the Kα2 ray it is 5887.6 eV. The energy of Co in the Kα1 ray is 6930.3 eV, and in the Kα2 ray it is 6915.3 eV. The energy of Ni in the Kα1 ray is 7478.1 eV, and in the Kα2 ray it is 7460.9 eV.

[0062] Generally, due to quantum fluctuations and noise in the detection system, the measured waveforms of Kα1 and Kα2 rays become peaks with a finite width, whose bottom portions overlap and are thus detected. Therefore, it is preferable to separate the peaks separately by curve fitting. For this purpose, it is necessary to continuously acquire data covering a specified energy range (wavelength range) for both rays.

[0063] As a suitable energy range (wavelength range) for waveform analysis, a reference standard is defined as the energy difference between Kα1 rays and Kα2 rays being at least twice, and preferably at least three times. In this embodiment, a Kα ray signal is acquired, but it is not limited to this; a Kβ ray signal can also be acquired. In this case, the Kα1 ray can be replaced with Kβ1,3 rays, and the Kα2 ray with Kβ' rays to calculate the suitable energy range (wavelength range).

[0064] Figures 5A-5C This is a graph showing the analysis results based on the detection results of detector 14. Figure 5A The results are about Fe. Figure 5BThe results are about Co. Figure 5C The results pertain to Ni. For example... Figure 5A As shown, the Kα1 and Kα2 spectral peaks of Fe can be appropriately detected at a specified position in the x-direction of detector 14. The Kα1 and Kα2 spectral peaks can also be appropriately detected for Co and Ni.

[0065] [Variation Example]

[0066] The following describes variations of this embodiment.

[0067] <Variation Example 1>

[0068] In this embodiment, such as Figure 2 As shown, the common beam splitting range 173 is configured to be defined by the length (L1) of the beam splitting surface of the beam splitting element 12 along the Rowland circle 104.

[0069] However, it is not limited to this; a collimator (collimator 180-183) may also be provided, which defines (determines) the common spectral range. The collimator is arranged on the path of the characteristic X-ray group from the sample holder 108 through the spectral element 12 to the detector 14.

[0070] Figure 6A , 6B This is a diagram showing an example of a collimator (collimator 180, 183). Figure 6A This is a diagram showing a single-aperture collimator 180. Figure 6B This is a diagram showing a collimator 183 with multiple openings.

[0071] like Figure 6A As shown, the single-aperture collimator 180 has one opening 181a. In contrast, as... Figure 6B As shown, the multi-aperture collimator 183 has three openings (openings 184a to 184c).

[0072] Figure 7 This is a diagram showing the relationship between the X-ray spectrophotometer 10a and the Rowland circle 104 in Modified Example 1. The configuration of the X-ray spectrophotometer 10a is basically the same as that of the X-ray spectrophotometer 10, except that it is further equipped with a collimator 180, so detailed description is omitted.

[0073] like Figure 7 As shown, the collimator 180 is disposed on the path of the characteristic X-ray group from the sample holder 108 through the beam splitter 12 to the detector 14. Specifically, by being disposed near the beam splitter 12, the common beam splitting range 173 is narrowed by the opening 181a of the collimator 180, thereby defining the beam splitting range.

[0074] That is, the common beam splitting range 173 is defined by the size of the opening 181a of the collimator 180, rather than by the size of the beam splitting element 12.

[0075] If the X-rays that become the signal irradiate the end of the beam splitter 12, unwanted scattered rays may sometimes be generated. Therefore, by arranging the collimator 180 as described above, the generation of unwanted scattered rays can be prevented.

[0076] <Variation Example 2>

[0077] Figure 8 This diagram shows the relationship between the X-ray spectrophotometer 10b and the Rowland circle 104 in Modified Example 2. The configuration of the X-ray spectrophotometer 10b is basically the same as that of the X-ray spectrophotometer 10, except that it is further equipped with collimators 181 and 182; therefore, detailed description is omitted. Collimators 181 and 182 are single-aperture collimators, the same as collimator 180.

[0078] like Figure 8 As shown, collimators 181 and 182 are disposed on the path of the characteristic X-ray group from the sample holder 108 through the beam splitter 12 to the detector 14. Specifically, collimator 181 is disposed on the path of the characteristic X-ray group from the sample holder 108 to the beam splitter 12, and collimator 182 is disposed on the path of the characteristic X-ray group from the beam splitter 12 to the detector 14, thereby defining a common beam splitting range 173.

[0079] <Variation Example 3>

[0080] Figure 9 This is a diagram showing the relationship between the X-ray spectrophotometer 10c of Modified Example 3 and the Rowland circle 104. The configuration of the X-ray spectrophotometer 10c is basically the same as that of the X-ray spectrophotometer 10, except that it is equipped with collimators 180 and 183, so detailed description is omitted.

[0081] like Figure 9 As shown, collimators 180 and 183 are disposed along the path of the characteristic X-ray group from the sample holder 108 through the beam splitter 12 to the detector 14. Specifically, collimator 180 is disposed near the beam splitter 12, and collimator 183 is disposed near the sample holder 108.

[0082] Fluorescent X-rays generated from Mn pass through the opening 184a of collimator 183 (shown by optical paths 125 and 127), fluorescent X-rays generated from Co pass through the opening 184b of collimator 183 (shown by optical paths 121 and 123), and fluorescent X-rays generated from Ni pass through the opening 184c of collimator 183 (shown by optical paths 117 and 119). Furthermore, the common beam splitting range 173 is narrowed by the opening 181a of collimator 180, thus defining the beam splitting range.

[0083] Thus, the collimator can also be a collimator that allows light of each wavelength range to pass through individually (collimator 183). By shielding X-rays outside the wavelength range of interest, the reduction in the SN ratio caused by scattered rays can be avoided.

[0084] <Variation Example 4>

[0085] Figure 10 This is a diagram showing the sample holder 109 and the rotation mechanism 110 of Modified Example 4. In this embodiment, the X-ray spectrophotometer 10 includes the rotation mechanism 110. The arithmetic unit 15 can control the rotation mechanism 110 to rotate the sample holder 108.

[0086] In this case, the sample holder 108 and the irradiation surface 108a are rectangular. However, it is not limited to this, and a rotation mechanism 110 can also be provided to rotate the circular sample holder 109 and the irradiation surface 109a. The diameter of the irradiation surface 109a is L2.

[0087] The sample within the sample holder 109 may not be held in a uniform state due to defects or bias. 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 higher reproducibility can be expected in the analysis results. Alternatively, the X-ray spectrophotometer 10 may not include the rotation mechanism 110.

[0088] <Other variations>

[0089] The beam splitter 12 can be a single crystal such as Si, Ge, LiF, or quartz, or it can use artificially added multilayer films for soft X-rays below 2keV. Alternatively, a diffraction grating with the same effect as a bent crystal can be used. The bending shape of the beam splitter 12 can be either Johann type or Johannson type.

[0090] The curved shape of the beam-splitting element 12 can be spherical or toroidal. Alternatively, if the central portion is close to a sphere, it can also be an elliptical, parabolic, or other shapes. As described above, the curvature of the beam-splitting direction (x-direction) and the converging direction (y-direction) is preferably Rx = 2R and Ry = 2R × sin 2 θ B The decision can be made, but strict consistency is not necessary. In particular, regarding the convergence direction, the curvature can be set to be the same as the beam splitting direction to consider ease of manufacturing.

[0091] The excitation beam can be X-rays, or it can be an electron beam, neutron beam, or proton beam. In addition, the position-sensitive detector 14 can also be a CCD or CMOS camera, which serves as a two-dimensional detector.

[0092] [plan]

[0093] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following solutions.

[0094] (Solution 1) The X-ray spectrophotometer of one solution includes an excitation source, a curved beam splitter, a position-sensitive detector, and a processing unit. The excitation source irradiates a sample held in a sample holder with excitation rays, generating characteristic X-ray groups with different peak wavelengths. The curved beam splitter disperses the characteristic X-ray groups. The position-sensitive detector detects at least a portion of the characteristic X-ray groups dispersed by the beam splitter. The processing unit analyzes the elements contained in the sample based on the detector's detection results. The beam splitter and detector are arranged along the circumference of a Rowland circle. The length of the beam splitting surface of the beam splitter along the Rowland circle is shorter than the length of the irradiation surface of the excitation rays irradiating the sample holder within the plane of the Rowland circle. The arrangement of the beam splitter and sample holder allows the characteristic X-ray groups to be dispersed through the common beam splitting range of the beam splitter.

[0095] According to the X-ray spectrophotometer described in the first embodiment, since the effective dispersive range of the curved-shaped spectrophotometer can be limited to the area near the circumference of the Rowland circle, the reduction in the detection accuracy of characteristic X-rays due to the difference in curvature radii between the Rowland circle and the spectrophotometer can be prevented. Therefore, fluorescent X-rays can be detected with high precision in the detector.

[0096] (Second Scheme) In the X-ray spectrophotometer described in the second scheme, the detector is configured such that its surface intersects the Rowland circle at two points.

[0097] The X-ray spectrophotometer described in Scheme 2 is capable of detecting X-rays of different energies at high resolution.

[0098] (Third embodiment) The X-ray spectrophotometer described in claim 1 further includes a collimator that defines a common spectrophotometric range. The collimator is disposed on the path of the characteristic X-ray group from the sample holder through the spectrophotometer to the detector.

[0099] The X-ray spectrophotometer according to the third embodiment can prevent the generation of unwanted scattered rays from the ends of the spectrophotometer.

[0100] (Solution 4) In the X-ray spectrophotometer described in Solution 1 or Solution 2, the collimator and each group of characteristic X-ray groups have multiple openings.

[0101] According to the X-ray spectrophotometer described in Scheme 4, by shielding characteristic X-rays outside the wavelength range of interest, the reduction in the SN ratio caused by scattered rays can be avoided.

[0102] (Fifth Scheme) In any one of the Schemes 1 to 4, the length of the beam-splitting surface of the beam-splitting element along the circumference of the Rowland circle, within the beam-splitting range, is less than 1 / 2 of the length of the irradiation surface within the surface of the Rowland circle.

[0103] According to the X-ray spectrophotometer described in the fifth embodiment, since the effective dispersive range of the curved-shaped spectrophotometer can be limited to the area near the circumference of the Rowland circle, the reduction in the detection accuracy of characteristic X-rays due to the difference in curvature radii between the Rowland circle and the spectrophotometer can be prevented. Therefore, fluorescent X-rays can be detected with high precision in the detector.

[0104] (Sixth Scheme) In the X-ray spectrophotometer described in Schemes 1 to 5, the detector is a one-dimensional detector.

[0105] According to the X-ray spectrophotometer described in Scheme 6, cost reduction of the device can be expected. Furthermore, there is no need to reconstruct two-dimensional data from a two-dimensional detector into one-dimensional data.

[0106] (Seventh embodiment) The X-ray spectrophotometer described in any one of the first to sixth embodiments further includes a rotation mechanism for rotating the sample holder.

[0107] According to the X-ray spectrophotometer described in Scheme 7, variations in peak intensity can be avoided, and high reproducibility of the analysis results can be expected.

[0108] The elemental analysis method according to Scheme 8 includes: irradiating an excitation beam onto a sample held in a sample holder to generate a set of characteristic X-rays with different peak wavelengths; incidenting the generated set of characteristic X-rays onto a curved beam-splitting element, splitting the incident set of characteristic X-rays by the beam-splitting element, and detecting at least a portion of the split set of characteristic X-rays by a position-sensitive detector; and analyzing the elements contained in the sample based on the detector's detection results. The beam-splitting element and the detector are arranged along the circumference of a Rowland circle, the length of the beam-splitting surface of the beam-splitting element along the Rowland circle is shorter than the length of the irradiation surface of the excitation beam irradiating the sample holder within the surface of the Rowland circle, and the beam-splitting element and the sample holder are arranged such that the set of characteristic X-rays is split through the common beam-splitting range of the beam-splitting element.

[0109] According to the elemental analysis method described in Scheme 8, since the effective dispersive range of the curved-shaped spectrometer can be limited to the area near the circumference of the Rowland circle, the reduction in the detection accuracy of characteristic X-rays due to the difference in curvature radii between the Rowland circle and the spectrometer can be prevented. Therefore, fluorescent X-rays can be detected with high precision in the detector.

[0110] The embodiments of the present invention have been described above, but it should be considered that the embodiments disclosed herein are illustrative rather than restrictive in all respects. The scope of the invention is set forth in the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. An X-ray spectrophotometer, characterized in that, have: An excitation source irradiates the sample held in the sample holder with excitation rays, producing a group of characteristic X-rays with different peak wavelengths. A curved beam-splitting element is used to split the characteristic X-ray group. A position-sensitive detector that detects at least a portion of the characteristic X-ray group after it has been dispersed by the spectroscopic element; The computing unit analyzes the elements contained in the sample based on the detection results of the detector. The beam splitter and the detector are arranged along the circumference of a Rowland circle. The length of the beam-splitting surface of the beam-splitting element along the Rowland circle is shorter than the length of the irradiation surface of the excitation rays irradiating the sample holder within the plane of the Rowland circle. The spectrometer and the sample holder are configured to separate the characteristic X-ray group through the common spectrometer range of the spectrometer. The beam splitting range is defined by the length of the beam splitting surface of the beam splitting element along the Rowland circle.

2. The X-ray spectrophotometer as described in claim 1, characterized in that, The detector is configured such that its surface intersects the Rowland circle at two points.

3. The X-ray spectrophotometer as described in claim 1, characterized in that, The length of the beam-splitting surface of the beam-splitting element along the circumference of the Rowland circle, within the beam-splitting range, is less than 1 / 2 of the length of the irradiation surface within the surface of the Rowland circle.

4. The X-ray spectrophotometer as described in claim 1, characterized in that, The detector is a one-dimensional detector.

5. The X-ray spectrophotometer as described in claim 1, characterized in that, It further includes a rotation mechanism for rotating the sample holder.

6. An X-ray spectrophotometer, characterized in that, have: An excitation source irradiates the sample held in the sample holder with excitation rays, producing a group of characteristic X-rays with different peak wavelengths. A curved beam-splitting element is used to split the characteristic X-ray group. A position-sensitive detector that detects at least a portion of the characteristic X-ray group after it has been dispersed by the spectroscopic element; A collimator is disposed on the path of the characteristic X-ray group from the sample holder through the beam-dispersing element to the detector; The computing unit analyzes the elements contained in the sample based on the detection results of the detector. The beam splitter and the detector are arranged along the circumference of a Rowland circle. The length of the beam-splitting surface of the beam-splitting element along the Rowland circle is shorter than the length of the irradiation surface of the excitation rays irradiating the sample holder within the plane of the Rowland circle. The spectrometer and the sample holder are configured to separate the characteristic X-ray group through the common spectrometer range of the spectrometer. The beam splitting range is defined by the collimator.

7. The X-ray spectrophotometer as described in claim 6, characterized in that, The collimator has multiple openings corresponding to each group of the characteristic X-ray groups.

8. An elemental analysis method, characterized in that, include: The step of irradiating a sample held in a sample holder with excitation rays to produce a group of characteristic X-rays with different peak wavelengths; The steps include: incident the generated characteristic X-ray group onto a curved beam splitter, splitting the incident characteristic X-ray group by the beam splitter, and detecting at least a portion of the split characteristic X-ray group by a position-sensitive detector; The step of analyzing the elements contained in the sample based on the detection results of the detector. The beam splitter and the detector are arranged along the circumference of a Rowland circle. The length of the beam-splitting surface of the beam-splitting element along the Rowland circle is shorter than the length of the irradiation surface of the excitation rays irradiating the sample holder within the plane of the Rowland circle. The spectrometer and the sample holder are configured to separate the characteristic X-ray group through the common spectrometer range of the spectrometer. The beam splitting range is defined by the length of the beam splitting surface of the beam splitting element along the Rowland circle or by the collimator.

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