Segmented crystal and analysis device provided with same

Abstract

Provided are: a segmented crystal which can easily be manufactured, has little aberration, and can assume a large take-in angle; and an analyzer equipped with the segmented crystal. This segmented (100) diffracts X-rays generated from an X-ray source on a crystal plane and condenses the X-rays. The segmented crystal (100) comprises: a first crystal surface (111a) that is formed of spectroscopic crystals (111-113) along a Rowland circle; and second crystal surfaces (112a, 113a) that are formed of the spectroscopic crystals and are connected to the first crystal surface (111a). The second crystal surfaces (112a, 113a) are inclined with respect to the first crystal surface (111a).

Description

Segment crystal and analytical apparatus equipped therewith

[0001] The present invention relates to a segment crystal that diffracts and focuses X-rays generated from an X-ray source at its crystal plane, and an analytical apparatus equipped therewith.

[0002] Conventionally, in the field of X-ray spectroscopy, Johann-type crystals and Johansson-type crystals are known as optical elements using spectroscopic crystals (for example, Non-Patent Document 1). Johann-type crystals have a crystal surface formed by a spectroscopic crystal curved to a curved surface with a radius of curvature twice the radius of the Rowland circle, and are designed to efficiently focus X-rays of a specific wavelength. Johansson-type crystals are designed so that the curvature of the crystal strictly matches the Rowland circle, further reducing astigmatism and achieving higher wavelength resolution. In addition to the above, three-dimensional curved X-ray reflective lenses manufactured from crystal wafers have also been developed as optical elements using spectroscopic crystals (for example, Patent Document 1).

[0003] Figures 1(a) and 1(b) are schematic diagrams showing the positions of the light source point S1 and the focal point F1 for a Johann-type crystal M1 and a Johansson-type crystal M2, respectively. The Johann-type crystal M1 merely approximates the Rowland circle C2 by a curved crystal surface along a circle C1 (hereinafter referred to as the "Johann circle" for convenience) having a radius twice that of the Rowland circle. At positions away from the center of the crystal surface, the deviation of the Johann circle C1 from the Rowland circle C2 is large, and the focal point F1 of the actual optical path P2 is shifted from the focal point V1 of the hypothetical optical path P1, which assumes reflection of X-rays incident from the light source point S1 on the Rowland circle, resulting in aberration. Therefore, the usable capture angle for the Johann-type crystal M1 is small. In contrast, the crystal surface of the Johansson-type crystal M2 strictly coincides with the Rowland circle C2, so no aberration occurs and the X-rays from the light source point S1 are focused at the focal point F1.

[0004] Patric Zimmermann, Sergey Peredkov, Paula Macarena Abdala, Serena DeBeer, Moniek Tromp, Christoph Muller, Jeroen A. van Bokhoven, “Modern X-ray spectroscopy: XAS and XES in the laboratory”, UK, Coordination Group Publications, Coordination Chemistry Reviews 423 (2020) 213466

[0005] Japanese Patent Publication No. 2013-113782

[0006] On the other hand, while the crystal surface of a Johann-type crystal can be easily formed by a curved spectroscopic crystal, forming the crystal surface of a Johanson-type crystal requires further polishing of the curved spectroscopic crystal surface until it precisely matches the curvature of the Rowland circle. Therefore, the manufacturing process for Johanson-type crystals is extremely difficult compared to that for Johann-type crystals.

[0007] This invention has been made in view of these circumstances, and aims to provide a segment crystal that can be easily manufactured, has low aberrations, and allows for a wide intake angle, as well as an analytical apparatus equipped therewith.

[0008] (1) To achieve the above objective, the segment crystal of the present invention is a segment crystal that diffracts and focuses X-rays generated from an X-ray source on a crystal surface, and comprises a first crystal surface formed of a spectroscopic crystal along a Rowland circle, and a second crystal surface formed of a spectroscopic crystal and connected to the first crystal surface, wherein the second crystal surface is inclined with respect to the first crystal surface.

[0009] (2) In addition, the segment crystal described in (1) above is characterized in that the second crystal surface coincides with the Rowland circle at at least one point within the plane of the second crystal surface and has a radius of curvature of 1.9 to 2.1 times that of the Rowland circle.

[0010] (3) In addition, the segment crystal described in (2) above is characterized in that the second crystal surface has a curved shape in which the radius of curvature is corrected according to the angular position of the arc of curvature.

[0011] (4) Furthermore, in the segment crystal described in (2) above, the corrected curved shape is characterized in that the difference between the radius of curvature and the Rowland circle is large as it moves away from the point of coincidence between the second crystal surface and the Rowland circle.

[0012] (5) Furthermore, in the segment crystal described in (4) above, when the direction perpendicular to the first crystal surface at the center of the first crystal surface is defined as the y-direction, and the direction perpendicular to the y-direction is defined as the x-direction, the correction amount of the radius of curvature in the y-direction is characterized by being expressed as a cubic function of the x-direction distance from the point of coincidence between the second crystal surface and the Rowland circle.

[0013] (6) The segment crystal described in any of (1) to (5) above is further characterized in that it comprises a third crystal surface which is formed at an inclination with respect to the second crystal surface and is connected to at least the second crystal surface.

[0014] (7) Furthermore, in the segment crystal described in any of (1) to (6) above, the crystal plane of the spectroscopic crystal forming the second crystal surface is formed such that it has an angular relationship that focuses the X-rays received on the second crystal surface onto the focal point on the Rowland circle.

[0015] (8) Furthermore, the segment crystal described in any of (1) to (7) above is characterized in that it is a two-dimensional curved crystal in which the first crystal surface and a crystal surface connected to the first crystal surface are formed on a cylinder whose central axis is a straight line connecting the light source point and the focusing point on the Rowland circle.

[0016] (9) Furthermore, an analytical apparatus comprising a segment crystal as described in any of (1) to (8) above, characterized by comprising: an irradiation unit that focuses X-rays generated by an X-ray source with the segment crystal; a sample holding unit that holds a sample at the irradiation position of the focused X-rays; and a detection unit that detects radiation generated by the irradiation of the sample with X-rays.

[0017] (a) and (b) are diagrams showing the positions of the light source point and the focusing point for a Johann-type crystal and a Johanson-type crystal, respectively. This diagram shows the relationship between the reflection position and focusing for a Johann-type crystal. (a) and (b) are enlarged views and tables showing the relationship between the reflection position and aberration for a Johann-type crystal, respectively. This is a cross-sectional view showing the relationship between the crystal surface and crystal plane of a segment crystal of the first embodiment. This diagram shows the relationship between the reflection position and focusing for a segment crystal formed with a constant radius of curvature. (a) and (b) are enlarged views and the maximum incident angle deviation (Δθ) showing the relationship between the reflection position and the maximum incident angle deviation (Δθ) for a segment crystal formed with a constant radius of curvature, respectively. max This is a table showing the radius of curvature of the second crystal surface and the focal aberration (Δθ) at the crystal edge. This is a diagram showing the center of curvature of the second crystal surface. This is a diagram showing the relationship between the reflection position and focusing of the corrected segment crystal. (a) and (b) are enlarged views showing the reflection position of the corrected segment crystal and a table showing the radius of curvature and aberration at each position of the corrected segment crystal. This is a diagram showing the relationship between the reflection position and focusing of the segment crystal in which the third crystal surface is connected. (a) and (b) are enlarged views showing the relationship between the reflection positions of the segment crystal in which multiple crystal surfaces are connected and the maximum incident angle deviation (Δθ) max This is a table showing the ) and focal aberration (ΔF) at the crystal edge. This is a perspective view showing a segment crystal of the second embodiment. This is a schematic diagram showing the analytical apparatus of the third embodiment.

[0018] Next, embodiments of the present invention will be described with reference to the drawings. To facilitate understanding of the description, the same reference numerals are used for identical components in each drawing, and redundant descriptions are omitted.

[0019] [Principle] In Johann-type crystals, a curved surface shape with a radius of curvature twice the radius of the Rowland circle (focal circle) is formed on the crystal surface. Therefore, aberrations occur at reflection positions with large capture angles. The aberrations at each reflection position of the Johann-type crystal can be calculated by setting the center of the Rowland circle C2 as the origin, defining the direction perpendicular to the crystal surface of the Johann-type crystal at the origin as the y-direction, and the direction perpendicular to the y-direction as the x-direction.

[0020] Figure 2 shows the relationship between the reflection position and focusing of light in a Johann-type crystal. Figures 3(a) and 3(b) are enlarged views and tables, respectively, showing the relationship between the reflection position and aberration in a Johann-type crystal. At the center of the crystal surface of a Johann-type crystal, the Johann circle C1 and the Rowland circle C2 coincide, and there is no aberration in the optical path P11 where light is reflected at that center. On the other hand, aberration occurs in the optical path P12 where light is reflected at a position away from the center of the crystal surface of a Johann-type crystal.

[0021] When a simulation of aberrations occurring in a Johann-type crystal formed along a Johann circle C1 with a radius of 500 mm is performed, the results shown in Figure 3(b) are obtained. The X-ray used is AlKα １ (λ = 8.3395 Å) was used, and SiO was used as the spectroscopic crystal. ２ Using a crystal (d = 4.25 Å), diffracted X-rays with a diffraction angle θ = 78° are selected by a Johann-type crystal (the same applies hereafter).

[0022] As shown in Figure 3(b), the maximum diffraction angle shift Δθ occurs at a capture angle (angle position from the center of the crystal surface relative to the light source point) of ±2°. ｍａｘ The angle is 0.007°, and the shift in the position of the focal point ΔF is 0.8 μm. Then, as the acquisition angle increases to ±3° and ±4°, the shift in the maximum diffraction angle Δθ ｍａｘ Furthermore, it can be seen that the displacement ΔF of the focal point is significantly large. The error in the focal position is extremely small, but the error in the angle of incidence is relatively large. Since an error of 0.03° in the diffraction half-width occurs at an angular position of ±4°, the diffraction intensity at both ends is too weak when using crystal surfaces of ±4° in size. Therefore, when using segmented crystal surfaces, it is preferable to make the size of a single crystal surface ±2°.

[0023] To reduce this deviation, i.e., the deviation in diffraction angle and aberration, it is ideal to use a Johanson-type crystal, but it is difficult to manufacture and expensive to adopt. In such cases, it is effective to prepare multiple spectroscopic crystals having crystal surfaces equivalent to those of a Johanson-type crystal, tilt them, and connect them in a composite manner to create a segmented crystal. This makes it possible to achieve crystal planes with angles close to those of a Johanson-type crystal. The details of segmented crystals are described below.

[0024] [First Embodiment] (Basic Configuration) Figure 4 is a cross-sectional view of the segment crystal 100. The segment crystal 100 is formed by combining segmented spectroscopic crystals 111 to 113. Each of the spectroscopic crystals 111 to 113 has crystal surfaces 111a to 113a that are shifted by the necessary angle relative to each other, and the crystal surfaces 111a to 113a are continuously connected by joining the spectroscopic crystals 111 to 113. However, the inclination of the crystal surfaces 111a to 113a is discontinuous at the connection point. The spectroscopic crystals 111 to 113 can be fixed by attaching them to a frame or holder.

[0025] In the segment crystal 100, the crystal surface 112a (second crystal surface) is formed at an inclination with respect to the crystal surface 111a (first crystal surface) and is connected to the crystal surface 111a. The crystal plane of the second spectroscopic crystal only needs to be inclined at a certain angle with respect to the crystal surface 112a. This allows for easy manufacturing, reduced aberrations, and a larger capture angle. Note that the "inclination" of the crystal plane with respect to the crystal surface refers to the relationship shown in Figure 4.

[0026] Preferably, the crystal surface 112a coincides with a Rowland circle at at least one point within the plane of the crystal surface 112a and has a radius of curvature 1.9 to 2.1 times that of the Rowland circle. Note that "coincidence" includes "intersection" and "inscribed". For example, "inscribed" means that the distance between the centers of the two circles is the difference in their radii, and "circumscribed" means that the distance between the centers of the two circles is the sum of their radii.

[0027] The crystal planes and crystal surfaces of the segment crystal 100 are designed to focus X-rays generated from the X-ray source onto a focal point. That is, the inclination of the crystal planes must be changed according to the angle of incidence of the X-rays onto the crystal surface. Specifically, the crystal planes must be inclined by the angular difference of the angle of incidence to different crystal planes depending on the incident position of the X-rays.

[0028] Specifically, as shown in Figure 4, the inclination of the Rowland circle (focusing circle) inscribed in the second spectroscopic crystal, which is centered at an angle α (for example, α = 4°) from the center, is 2α. In other words, the second spectroscopic crystal is positioned at an angle of 2α. The crystal plane of the second crystal is tilted by α with respect to its crystal surface. Therefore, the angle of incidence of X-rays on the crystal plane shifted by angle α coincides with the angle of incidence on the crystal plane of the first crystal located at the center. In practice, each crystal is curved along a radius approximately twice the radius of the focusing circle.

[0029] A segmented crystal surface of the segmented crystal 100, including the center of the crystal surface, is defined as the first crystal surface. A crystal surface formed at an angle to the first crystal surface and connected to the first crystal surface can be defined as the second crystal surface. Specifically, in the segmented crystal 100, crystal surface 111a corresponds to the first crystal surface, and crystal surfaces 112a and 113a correspond to the second crystal surfaces.

[0030] Because the crystal surfaces 111a to 113a are connected at different inclinations, the crystal surface of the segment crystal 100 is formed generally along the Rowland circle. As a result, X-rays can be diffracted with small aberrations from the crystal plane of the spectroscopic crystal and focused to a focal point on the Rowland circle.

[0031] Furthermore, the crystal planes of the spectroscopic crystals 111 to 113 are formed such that, at positions where each crystal surface coincides with the Rowland circle, they have an angular relationship that focuses the X-rays diffracted at the crystal surface to a focal point on the Rowland circle C2. In other words, the spectroscopic crystals 111 to 113 are Johann-type crystals with adjusted crystal surface shapes and crystal orientations. This allows the X-rays to be focused to a focal point on the Rowland circle C2.

[0032] Note that the crystal surface 112a is preferably formed such that at least one point on the crystal surface 112a is located on the Rowland circle C2, and the crystal plane of the spectroscopic crystal 112 is preferably formed such that the center of the spectroscopic crystal 112 is inscribed in the Rowland circle C2. This facilitates the design for reducing aberration. Also, although FIG. 4 depicts each crystal in a planar manner, the actual segment crystals 111, 112, and 113 are curved with a curvature approximately twice that of the Rowland circle. Also, the joining structure does not necessarily have to match the example shown in the figure.

[0033] (Constant Radius of Curvature) Each spectroscopic crystal constituting the segment crystal 100 can be formed by curving with a constant radius of curvature. In this case, since the curved surface shape of the crystal plane is the same as the curved shape of the crystal surface, the segment crystal 100 can be easily designed and the manufacturing also becomes simple. Note that the corrected curved surface shape has a larger difference between the radius of curvature and the Rowland circle as it moves away from the coincidence point between the second crystal surface and the Rowland circle C2.

[0034] Define the center of the Rowland circle C2 as the origin, the direction perpendicular to the crystal surface of the segment crystal 100 as the y - direction, and the direction perpendicular to the y - direction on the optical path surface as the x - direction (the same applies hereinafter). The y - direction can also be said to be the direction perpendicular to the crystal surface 111a (the first crystal surface).

[0035] However, the center of curvature of the crystal surface 112a (the second crystal surface) needs to be shifted from the center of curvature of the crystal surface 111a (the first crystal surface). Thereby, a curved surface shape inclined from the crystal surface 111a can be formed as the crystal surface 112a, and a crystal surface inscribed in the Rowland circle C2 can be formed. When the center of curvature of the crystal plane of the spectroscopic crystal 112 is represented as (x ｃ , y ｃ ), the circle C12 with a radius of 500 representing the shape of the crystal surface 112a is represented by the following mathematical formula.

[0036] FIG. 5 is a diagram showing the relationship between the reflection position and the light collection of a segment crystal formed with a constant radius of curvature. FIGS. 6(a) and (b) are enlarged diagrams showing the relationship of the reflection positions of a segment crystal formed with a constant radius of curvature and the maximum value of the incident angle deviation (Δθ ｍａｘThis is a table showing the focal aberration (ΔF) at the crystal edge. Figure 7 shows the curvature center of the second crystal surface. The intake angle ∠R0S1R2x is determined by the center R0 of the crystal surface 111a (first crystal surface), the X-ray source point S1, and the reflection point R2x (e.g., R21, R22...) and the angle θ Ｒ This is expressed as follows. In the example shown in Figure 5, the reflection positions R21 to R25 of the X-ray optical paths P21 to P25 are each the angle θ of the acquisition angle. Ｒ This corresponds to +2°, 0°, -2°, -4°, and -6°.

[0037] Using x and y coordinates, the aberrations at each reflection position of the segment crystal 100 can be calculated. When a simulation is performed assuming a segment crystal 100 with a crystal surface formed along a Rowland circle with a diameter of 500 mm, the results shown in Figure 6(b) are obtained.

[0038] As mentioned above, in Johann-type crystals, aberrations become large in the region where the incorporation angle is 2° or more, so it is preferable to use a crystal surface with an incorporation angle of ±2°. For this reason, in the simulation, a first crystal surface with an incorporation angle of ±2° centered on R0 is provided, and a second crystal surface with a size of ±2°, whose curvature center is shifted by a 4° inclination, is provided so that its center coincides with the position of 4° (R24).

[0039] For the crystal surface 111a (the first crystal surface), the maximum diffraction angle shift Δθ occurs at a position where the acquisition angle (the angular position from the center of the crystal surface relative to the light source point) is ±2°. ｍａｘ The angle is 0.007°, and the shift in the position of the focal point ΔF is 0.8 μm. In contrast, for the crystal surface 112a (second crystal surface), the maximum diffraction angle shift Δθ is at a position where the incorporation angle is ±2°. ｍａｘ The plane displacement is 0.009°, and the displacement ΔF of the focal point is 41 μm. Therefore, the displacement of the crystal planes is reduced compared to the Johann-type crystal. However, the aberration of the focal point is large in the crystal of the second spectroscopic crystal. In the above example, a crystal surface with a size of ±2° is used as the second crystal surface, but other sizes of crystal surfaces such as ±1° can also be used.

[0040] (Corrected radius of curvature) As described above, when using crystal planes with a size of ±2° as the second crystal, aberrations occur in reflections at positions far from the crystal center. To further reduce these aberrations, it is effective to apply a correction to the radius of curvature of the second crystal surface.

[0041] Figure 8 shows the relationship between the reflection position and focusing of the corrected segment crystal. Figures 9(a) and 9(b) are enlarged views showing the reflection position of the corrected segment crystal and a table showing the radius of curvature and aberration at each position of the corrected segment crystal, respectively. In the example shown in the figure, the reflection positions R41 to R45 in the X-ray optical path P41 to P45 are the same as the angle θ of the acquisition angle. Ｒ This corresponds to -2°, -3°, -4°, -5°, and -6°.

[0042] In the simulation, a second crystal surface with an incorporation angle of ±2° is provided so that its center coincides with a position of 4° (R44). At this time, x = -34.79 at the center of the second crystal surface, x = -51.95 at a position +2° from the center of the second crystal surface, and x = -17.39 at a position -2° from the center.

[0043] In the example shown in Figure 8, the basic radius of curvature of the second crystal surface is set to twice the radius of the Rowland circle C2, and the curved surface shape is formed by correcting the radius of curvature according to the angular position of the curvature arc. This makes it possible to form a crystal surface with further reduced aberrations. This curved surface shape is shown as arc C12a. Note that in Figure 8, the difference between the Rowland circle C2 and arc C12a is very small, and they are almost indistinguishable.

[0044] As for the corrected curved surface shape, the correction value of the radius of curvature can be increased as the distance from the point of agreement between the second crystal surface and the Rowland circle C2 (the center position of the second crystal surface) within the plane of the second crystal surface increases. This makes it easy to design a crystal surface with further reduced aberrations. Specifically, the amount of correction of the radius of curvature in the y direction can be expressed as a cubic function of the x-direction distance from the point of agreement between the second crystal surface and the Rowland circle C2 (for example, the center) of the second crystal surface.

[0045] Examples of cubic functions include the following equation. Note that a is an adjustment coefficient used for fitting, and x ｃｅｎｔｅｒ This is the x-coordinate of the center position of the second crystal surface.

[0046] In this case, the radius of curvature R of the second crystal surface is expressed by the following formula. Note that when y = f(x) represents the curved shape of the second crystal surface, y' and y'' are the first derivative of y with respect to x and the second derivative of y with respect to x, respectively. y = f(x) can be obtained from formula (1) or formulas (1) and (2).

[0047] Using the above formulas and xy coordinates, the aberrations at each reflection position of the segment crystal 100 can be calculated, as shown in Figure 9(b). When a simulation is performed assuming a segment crystal 100 with a crystal surface formed along a Rowland circle with a diameter of 500 mm, the results shown in Figure 9(b) are obtained. For example, at a position where the acquisition angle (angle position from the center of the crystal surface relative to the light source point) is +2°, the maximum diffraction angle shift Δθ is obtained. ｍａｘ The angle is 0.0068°, and the shift ΔF of the focal point is 2.8 μm. Since it is kept below this level at other angular positions, it can be seen that aberrations have been reduced well.

[0048] (Multiple Connections) As described above, aberrations can be reduced by correcting the radius of curvature of the second crystal surface from a constant value, but to correct focal aberration, it is effective to add a new crystal surface. To form a new crystal surface, at least one more inclined crystal surface may be connected in series. Figure 10 shows the relationship between the reflection position and focusing of a segment crystal to which a third crystal surface is connected. Figures 11(a) and (b) are enlarged views showing the relationship between the reflection positions of a segment crystal to which multiple crystal surfaces are connected, and the maximum incident angle deviation (Δθ), respectively. max This is a table showing the focal aberration (ΔF) at the crystal edge. In the example shown in the figure, the reflection positions R51 to R55 of the X-ray optical paths P51 to P55 correspond to the angle θ of the third crystal surface along the arc C13a. Ｒ This represents -6°, -7°, -8°, -9°, and -10°.

[0049] For example, in the example shown in Figure 10, the segment crystal 100 is formed at an even greater inclination with respect to the second crystal surface and includes a third crystal surface connected to the second crystal surface. This makes it possible to form a crystal surface that reduces aberrations even at an angle of incorporation far from the center of the crystal surface of the segment crystal 100, and to take a large incorporation angle. The curved shape of the third crystal surface is shown as an arc C13a.

[0050] In the simulation, a third crystal surface with a size of ±2° incorporation angle, whose center of curvature is shifted by an 8° inclination, is provided such that its center coincides with the 8° position (R53). At this time, x = -68.91 at the center of the third crystal surface, x = -85.50 at a position -2° from the center of the third crystal surface, and x = -51.95 at a position +2° from the center.

[0051] In this case, the correction for the radius of curvature of the third crystal surface can be expressed by the following formula. Note that the coefficient a is x - x ｃｅｎｔｅｒ When it is positive, a ＋ Using x - x ｃｅｎｔｅｒ When it is negative, a － It uses this.

[0052] Using xy coordinates, the aberrations at each reflection position of the segment crystal 100 can be calculated. When a simulation is performed assuming a segment crystal 100 with a crystal surface formed along a Rowland circle with a diameter of 500 mm, the results shown in Figure 9(b) are obtained. For example, at a position where the acquisition angle (angle position from the center of the crystal surface relative to the light source point) is +2°, the maximum diffraction angle shift Δθ is obtained. ｍａｘ The aberration is 0.0068°, the shift ΔF at the focal point is 2.8 μm, and it is kept below this at other angular positions, indicating that aberrations have been significantly reduced.

[0053] In the above example, the segment crystal 100 has up to the third crystal surface, but it may also have a fourth crystal surface connected to the third crystal surface, and similarly, it may have an nth crystal surface (5 ≤ n).

[0054] [Second Embodiment] In applications requiring a large diffraction angle and high energy resolution, the size of the crystal in the axial direction is limited, making it difficult to achieve a large acquisition angle with a two-dimensional curved crystal that normally offers high energy resolution and low aberration. However, by applying the segment crystal 200 to a two-dimensional curved crystal, aberrations can be reduced, and the X-ray acquisition angle can be increased.

[0055] Figure 12 is a perspective view showing a segment crystal 200 configured as a two-dimensional curved crystal. The segment crystal 200 is a two-dimensional curved crystal in which a first crystal surface and a second crystal surface are formed on a cylinder whose central axis is a straight line connecting a light source point S1 and a focal point F1 on a Rowland circle. This allows a large number of X-rays to be captured by the two-dimensionally extending crystal surface and focused as high-intensity X-rays.

[0056] [Third Embodiment] The segment crystal 200 can be applied to applications requiring a large diffraction angle and high energy resolution, such as XPS. Figure 13 is a schematic diagram showing the analytical apparatus 300. The analytical apparatus 300 includes an irradiation unit 310, a segment crystal 200, a sample holding unit 330, an electrostatic hemispherical analyzer 350, and a detection unit 360.

[0057] The irradiation unit 310 has an electron source 312 and a target 315. When the electron beam emitted from the electron source 312 strikes the target 315, X-rays are generated. The segment crystal 200 focuses the generated X-rays. The sample holding unit 330 holds the sample S0 at the irradiation position of the focused X-rays.

[0058] The electrostatic hemispherical analyzer 350 collects electrons generated from the sample S0 at different locations according to their energy levels. The detection unit 360 detects electrons generated by X-ray irradiation of the sample S0. In this way, the segment crystal 200 can be applied to analytical devices such as XPS that require localized high-intensity X-ray irradiation.

[0059] This application claims priority based on Japanese Patent Application No. 2025-014804, filed on 31 January 2025, and the entire contents of Japanese Patent Application No. 2025-014804 are incorporated herein by reference.

[0060] 100, 200 Segment crystal 111-113 Spectroscopic crystal 111a-114a Crystal surface 300 Analytical device 310 Irradiation unit 312 Electron source 315 Target 330 Sample holder 350 Electrostatic hemispherical analyzer 360 Detection unit C1 Johann circle C12 Circle C12a, C13a Circular arc C2 Rowland circle F1 Focus point S1 Light source point V1 Virtual focus point M1 Johann type crystal M2 Johanson type crystal P1, P2 Optical path P11, P12 Optical path P21-P25 Optical path P41-P45 Optical path P51-P55 Optical path R21-R25 Reflection position R41-R45 Reflection position R51-R55 Reflection position R: Radius of curvature, S0: Sample, ΔF: Shift in the position of the focal point, Δθ: ｍａｘ Shift in the maximum diffraction angle

Claims

1. A segment crystal for focusing X-rays generated from an X-ray source by diffraction of the crystal surface, comprising: a first crystal surface formed of a spectroscopic crystal along a Rowland circle; and a second crystal surface formed of a spectroscopic crystal and connected to the first crystal surface, wherein the second crystal surface is inclined with respect to the first crystal surface.

2. The segment crystal according to claim 1, characterized in that the second crystal surface coincides with the Rowland circle at at least one point within the plane of the second crystal surface and has a radius of curvature of 1.9 to 2.1 times that of the Rowland circle.

3. The segment crystal according to claim 2, characterized in that the second crystal surface has a curved shape in which the radius of curvature is corrected according to the angular position of the curved arc.

4. The segment crystal according to claim 2, characterized in that the difference between the radius of curvature and the Rowland circle is greater as the corrected curved shape moves away from the point of coincidence between the second crystal surface and the Rowland circle.

5. The segment crystal according to claim 4, characterized in that, when the direction perpendicular to the first crystal surface at the center of the first crystal surface is defined as the y-direction and the direction perpendicular to the y-direction is defined as the x-direction, the correction amount of the radius of curvature in the y-direction is expressed as a cubic function of the distance in the x-direction from the point of coincidence between the second crystal surface and the Rowland circle.

6. The segment crystal according to any one of claims 1 to 5, further comprising a third crystal surface formed at an inclination with respect to the second crystal surface and connected to at least the second crystal surface.

7. The segment crystal according to any one of claims 1 to 6, characterized in that the crystal plane of the spectroscopic crystal forming the second crystal surface is formed such that it has an angular relationship that focuses the X-rays received on the second crystal surface to a focal point on the Rowland circle.

8. The segment crystal according to any one of claims 1 to 7, characterized in that the first crystal surface and a crystal surface connected to the first crystal surface are formed on a cylinder whose central axis is a straight line connecting the light source point and the focusing point on the Rowland circle, wherein the first crystal surface and a crystal surface connected to the first crystal surface are formed on the cylinder.

9. An analytical apparatus comprising a segment crystal according to any one of claims 1 to 8, the apparatus comprising: an irradiation unit for focusing X-rays generated by an X-ray source with the segment crystal; a sample holding unit for holding a sample at the irradiation position of the focused X-rays; and a detection unit for detecting radiation generated by the irradiation of the sample with X-rays.

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