JP3923151B2 - X-ray concentrator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an X-ray condensing apparatus suitably used for an apparatus that performs X-ray diffraction measurement by irradiating a micro area of a sample, such as a micro area X-ray diffractometer or a point focusing camera apparatus. The present invention relates to an X-ray condensing apparatus that condenses X-rays that diverge from an X-ray source and travel in a dot shape.
[0002]
[Prior art]
In an X-ray diffractometer such as a micro-region X-ray diffractometer, a point focusing camera device, a small angle scattering device, etc., X-rays emitted from an X-ray source are irradiated onto a micro region of a sample. Conventionally, in order to guide X-rays emitted from an X-ray source to a microscopic area of a sample, a so-called collimator is used to limit the cross-sectional diameter of the X-rays, or two reflectors or reflections arranged in a positional relationship orthogonal to each other. Techniques such as condensing X-rays using a mirror are used. When using a collimator, for example, as shown in FIG. 7, a collimator 51 is provided at an upstream position of the sample S on the X-ray optical path between the X-ray source F and the sample S. The collimator 51 irradiates the sample S while limiting the X-ray R to a parallel beam with a minute cross section.
[0003]
When two reflectors are used, a pair of slits 52 and 52 are provided on the optical axis between the X-ray source F and the sample S as shown in FIG. The reflectors 54 are arranged at a right angle relative to each other. Then, the X-ray R traveling while diverging is reflected in two by the reflectors 53 and 54 to bend the optical axis in two directions, and is focused on an irradiation object, for example, an X-ray film 55 in a dot shape.
[0004]
However, since the collimator 51 shown in FIG. 7 merely limits a part of the X-ray R to parallel light with a minute cross section, there is a limit to the light collecting performance of collecting light. The X-ray concentrator shown in FIG. 8 has a function of condensing X-rays, but is configured to bend the X-rays R in two directions, that is, to reflect the X-rays twice. There is a problem of significant attenuation.
[0005]
In order to solve the above problems, the present inventor disclosed in Japanese Patent Laid-Open Nos. 5-332954 and 8-128970, an X-ray reflecting mirror having a cylindrical surface is perpendicular to the X-ray optical path. An X-ray condensing device having a structure curved in a convex direction has been proposed. According to this X-ray condensing device, since only one reflecting mirror is used, it is possible to obtain special effects such as easy adjustment of the optical axis and minimization of X-ray intensity attenuation. it can.
[0006]
[Problems to be solved by the invention]
However, with respect to the X-ray reflecting mirrors disclosed in these publications, the X-ray reflecting surface must be formed in a cylindrical surface and must be curved with respect to the X-ray optical path. Processing for forming the X-ray reflecting surface into a cylindrical shape is very difficult, and it is also very difficult to curve the cylindrical X-ray reflecting surface with high accuracy.
The present invention has been made to solve the above-described problems, and provides an X-ray condensing apparatus which can form an X-ray condensing beam having a practically sufficient intensity and has a very simple structure. For the purpose.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an X-ray condensing apparatus according to the present invention is an X-ray condensing apparatus that condenses characteristic X-rays radiated from an X-ray source. A flat plate-shaped first flat plate monochromator disposed on the traveling path of the line, and a flat plate-shaped second flat plate monochromator disposed downstream of the first flat plate monochromator with respect to the X-ray traveling path has, wherein the first flat plate monochromator and the second flat monochromator are arranged in perpendicular position relative to each other, further wherein the first flat monochromator and a second flat monochromator is formed by a mosaic crystal It is characterized by that.
[0008]
In the above configuration, the “mosaic angle width” represents the angular spread of the diffraction line intensity generated due to the so-called crystal mosaic structure, and can be measured by, for example, a measurement system as shown in FIG. . In this measurement system, X-rays radiated from the X-ray source F are shaped into a parallel X-ray beam by the monochromator 56 and irradiated to the sample crystal S, and the sample crystal S is centered on the sample axis L in a minute angle range. The intensity of the diffraction line is measured by the X-ray counter 57 while rotating, so-called ω rotation. As shown in FIG. 4, the measurement result appears as a chevron-shaped diffraction line figure on a graph having the ω rotation angle (ω) and the diffraction line intensity (I) as orthogonal coordinate axes.
[0009]
The width W of such a diffraction line pattern indicates the mosaic angle width of the crystal S. Since the complete crystal formed of one crystal as a whole has almost no mosaic structure, the mosaic angle width W becomes very narrow as W ₂ . On the other hand, in a crystal in which a large number of microcrystal pieces are stacked to form a mosaic, that is, a so-called mosaic crystal, the mosaic angle width W is wide as W ₁ . Since the intensity of the X-ray diffracted by the crystal appears as the area of the diffraction line pattern, that is, an integral value, the crystal having a wide mosaic angle width W has a higher X-ray intensity than a crystal having a narrow mosaic angle.
[0010]
The “crystal with a wide mosaic angle width” used in the present invention means a crystal having a narrow mosaic angle width, for example, a perfect crystal made of a single crystal such as germanium or silicon. As such a “crystal with a wide mosaic angle width”, the above-mentioned mosaic crystal, for example, pyrolithic graphite, which is graphite formed by thermal synthesis, can be used.
[0011]
According to the X-ray condensing apparatus of the present invention having the above-described configuration, the flat monochromator is formed by the crystal having a wide mosaic angle width, so that the X-rays diffracted by the flat monochromator can be focused linearly. Since at least two flat monochromators are prepared and arranged so as to cross each other, the X-ray beam focused linearly by the action of the flat monochromator at the first stage is 2 By the action of the flat plate monochromator at the stage, it can be finally focused in a dot shape.
[0012]
If a spectroscopic optical system is configured using a crystal having a narrow mosaic angle width such as germanium or silicon, the energy resolution of the spectroscopic optical system may be high. However, since the diffracted X-ray obtained by the spectroscopic optical system has a narrow divergence angle, the intensity of the obtained X-ray becomes low. On the other hand, according to the present invention in which the spectroscopic optical system is configured using a crystal having a wide mosaic angle width, the divergence angle of the obtained diffracted X-rays is wide, so that a focused X-ray beam with high intensity can be obtained.
[0013]
For example, pyrolitec graphite can be used as “a crystal having a wide mosaic angle width”, and for this pyrolitek graphite, the mosaic angle width W in FIG. 4 is 0.3 to 0.5 ° in half width. Including the area of the skirt and the skirt, it is about 1 °. If a spectroscopic optical system is configured using such a crystal having a wide mosaic angle width, the divergence angle of the X-ray beam is increased, and therefore a focused X-ray beam having high intensity can be obtained.
[0014]
Further, as shown in FIG. 7, the X-ray optical system using the collimator 51 has a structure in which only the X-rays emitted from the X-ray source F are extracted from the X-ray source F that passes through the collimator 51. It is a very small part of the X-rays emitted from the X-ray source F. Therefore, the intensity of the obtained X-rays is very low. On the other hand, in the X-ray condensing apparatus according to the present invention having the above-described configuration, the X-ray beam having a small cross-sectional area is formed by converging the X-ray beam in a dot shape. Is very high compared to the device of FIG.
[0015]
Furthermore, in the X-ray condensing apparatus disclosed in Japanese Patent Laid-Open Nos. 5-332954 and 8-128970, the X-ray reflecting surface is formed in a cylindrical shape, and the X-ray reflecting surface travels through the X-ray reflecting surface. It must be curved with high accuracy so as to be convex in a direction perpendicular to the direction. It is very difficult to form the X-ray reflection surface in a cylindrical shape, and it is also very difficult to curve the X-ray reflection surface with high accuracy. On the other hand, in the X-ray condensing apparatus according to the present invention having the above-described configuration, the pair of flat plate monochromators need only be arranged at a right angle relative to each other.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 shows an embodiment in which the X-ray focusing apparatus according to the present invention is applied to a micro-region X-ray diffraction apparatus. First, the outline of the micro-region X-ray diffraction apparatus denoted as a whole by reference numeral 10 will be described. At the condensing point O where the X-ray R emitted from the X-ray source F provided in the X-ray tube 19 is condensed. Χ (chi) axis, ω axis, and φ axis that are orthogonal to each other and three-dimensionally are set. A holder 11 is provided on the ω axis, another holder 13 is provided on the χ axis passing through the end of the holder 11, and a sample holder 15 is provided on the φ axis passing through the end of the holder 13. .
[0017]
The holder 11 around the ω axis is driven and rotated by a pulse motor 12, the holder 13 around the χ axis is driven and rotated by a pulse motor 14, and the sample holder 15 is driven and rotated by a pulse motor 16. The sample S to be measured is attached to the X-ray condensing point O at the tip of the sample holder 15. By driving the three pulse motors 12, 14, and 16 to rotate the holders 11, 13, and 15, the sample S is rotated three-dimensionally. As a result, various regions on the surface of the sample S are X-rayed. It can be carried to the condensing point O of R.
[0018]
A PSPC (Position Sensitive Proportional Counter) 17 as an X-ray detector is disposed on the opposite side of the holders 11, 13, and 15 with respect to the sample S. The PSPC 17 is also called a position-sensitive X-ray detector, and its detailed structure is widely known and will not be described in detail. Basically, the PSPC 17 is internally passed through an arc-shaped opening 18. It is an X-ray detector that simultaneously measures positional information and X-ray intensity in the direction of diffraction angle 2θ with respect to X-rays to be captured. The X-ray diffracted by the sample S is taken into the PSPC 17 through the opening 18 and the positional information and the X-ray intensity regarding the X-ray are simultaneously measured. Based on the measurement result, the crystal structure inside the sample S is determined.
[0019]
In the microregion X-ray diffractometer 10 as described above, the X-ray condensing device 1 is disposed on the X-ray optical axis between the X-ray tube 19 and the sample S. As shown in FIG. 1, the X-ray condensing device 1 is disposed on a traveling path of X-rays R that are radiated from an X-ray source F and travel, and has a flat plate-shaped first flat plate monochromator 2a, It has the 2nd flat plate monochromator 2b of the flat plate shape arrange | positioned in the downstream position of the 1st flat plate monochromator 2a regarding the X-ray advancing path | route.
[0020]
Both of these monochromators 2a and 2b are made of pyrolithic graphite, that is, a crystalline material formed by thermal synthesis of graphite into a desired flat plate shape. This pyrolithic graphite has the characteristic that the mosaic angle width is wide as indicated by the symbol P in FIG. 4, and therefore has the characteristic that the diffracted X-ray divergence angle is large and the diffracted X-ray intensity is high.
[0021]
The first flat plate monochromator 2a and the second flat plate monochromator 2b are arranged so as to cross each other. In the present embodiment, the first flat monochromator 2a is arranged in the vertical direction and the second flat monochromator 2b is arranged in the horizontal direction. Although the relative angle between the two monochromators 2a and 2b is considered to be substantially a right angle, various values may be taken depending on the situation. What is important is that both the monochromators 2a and 2b are set at an appropriate relative angle so that the X-ray R can be focused in a point-like manner at the target focusing point O.
[0022]
Since the X-ray condensing apparatus 1 of the present embodiment is configured as described above, the X-rays generated from the dotted X-ray source F are 2 of the first flat plate monochromator 2a and the second flat plate monochromator 2b. After being diffracted by a single monochromator, the light is condensed in a spot shape at a condensing point O. Since the mosaic angle width of pyrolithic graphite constituting the first flat monochromator 2a is about 0.3 ° to 0.5 ° in half width, the X-ray diffracted by the first flat monochromator 2a is monochromatic. The light is condensed linearly at a position Q symmetrical about the X-ray source F with the meter 2a as the center. The angular width of the diffracted X-ray at that time corresponds to the mosaic angular width. By diffracting the X-rays collected linearly by the second flat plate monochromator 2b, the X-rays R can be finally focused on the target condensing point O. If a sample is placed at the condensing point O, a high-intensity X-ray can be irradiated to a minute region of the sample.
[0023]
According to the X-ray condensing apparatus of the present embodiment, when the X-ray optical system is configured using the collimator 51 as shown in FIG. 7, or using a crystal having a narrow mosaic angle width such as germanium or silicon. Compared with the case where a spectroscopic optical system is constructed, a focused X-ray beam having high intensity can be obtained. Moreover, in the X-ray condensing apparatus of this embodiment, it is not necessary to process the X-ray reflecting surface into a cylindrical surface shape or the like, and it is not necessary to curve the flat plate monochromators 2a and 2b. The device can be made very easily.
[0024]
Since there is a mechanical distance between the first flat plate monochromator 2a and the second flat plate monochromator 2b, the X-ray source F and the condensing point O are not strictly symmetrical. It will not be. In addition, regarding the monochromators 2a and 2b made of pyrolithic graphite, the X-rays penetrate into the interior of the monochromators 2a and 2b, so that the diffracted X-ray beam spreads in the thickness direction of the monochromators. There is a risk of blurring at the focal point. However, the blur can be reduced by reducing the thickness of the monochromators 2a and 2b. A specific thickness dimension is desirably the same as that of the X-ray source F, and is set to about 0.1 mm, for example.
[0025]
Note that, as shown in FIG. 5, the first flat plate monochromators 2a and 2b shown in FIG. However, these monochromators 2a and 2b can be curved so that the X-ray incident surface is concave as shown in FIG. The divergence angle θ2 of the incident X-ray R that can be taken into the monochromators 2a and 2b in the curved state shown in FIG. 6 can be made larger than the divergence angle θ1 in the planar state shown in FIG. As a result, the X-ray intensity of the characteristic X-ray obtained when the monochromators 2a and 2a are curved can be made stronger than the intensity in the planar state. That is, it is possible to obtain an X-ray beam having an angle wider than the mosaic angle width of Pyrolithic graphite by curving the flat plate chromometers 2a and 2b.
[0026]
The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the embodiments, and various modifications can be made within the scope of the invention described in the claims.
For example, in the above embodiment, pyrolithic graphite is used as a crystal having a wide mosaic angle width, but other crystals can be used as long as the crystal has a wider mosaic angle width than a complete crystal made of a single crystal such as germanium or silicon. Can also be used. Moreover, in the said embodiment, although the X-ray condensing apparatus of this invention was applied to the micro area | region X-ray-diffraction apparatus, this invention is applied to the other arbitrary X-ray apparatuses which need to condense an X-ray. Can do.
[0027]
【The invention's effect】
According to the X-ray concentrating device of claim 1, the X-rays generated from the X-ray source are punctured by diffracting the X-rays by a pair of flat plate monochromators formed of crystals having a wide mosaic angle width. Can be focused. Compared to the case where an X-ray optical system using a collimator is used, or a case where a spectroscopic optical system is configured using a crystal having a narrow mosaic angle width such as germanium or silicon, a focused X-ray beam having a higher intensity is used. Can be obtained. In addition, there is no need to process the X-ray reflecting surface into a cylindrical shape or to bend the entire monochromator with high accuracy, and the simple monochromator is used because it is simply a flat monochromator. it can.
[0028]
The X-ray condensing apparatus according to claim 2 can be formed using pyrolithic graphite which is readily available at present. Since this crystal has a larger mosaic angle width than a single crystal monochromator, it is possible to obtain diffracted X-rays with high intensity.
[0029]
According to the X-ray condensing apparatus of the third aspect, it is possible to obtain a wide mosaic angle width as compared with the single crystal monochromator, and thus to obtain a diffracted X-ray having a high intensity.
[0030]
According to the X-ray condensing apparatus of the fourth aspect, the divergence angle of the incident X-ray that can be taken into the monochromator can be increased, and therefore the intensity of the X-ray diffracted by the monochromator can be increased. .
[0031]
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of an X-ray focusing apparatus according to the present invention.
FIG. 2 is a perspective view showing an example of usage of the X-ray focusing apparatus.
FIG. 3 is a diagram schematically showing an example of an X-ray measurement system for measuring a mosaic angle width related to a crystal.
FIG. 4 is a graph showing the mosaic angle width for crystals.
FIG. 5 is a diagram showing a divergence angle of incident X-rays that can be captured by a flat plate monochromator.
FIG. 6 is a diagram showing a divergence angle of incident X-rays that can be captured by a curved flat plate monochromator.
FIG. 7 is a perspective view showing an example of a conventional X-ray optical system for narrowing the cross-sectional shape of an X-ray beam.
FIG. 8 is a perspective view showing an example of a conventional X-ray focusing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 X-ray condensing device 2a 1st flat plate monochromator 2b 2nd flat plate monochromator 10 Micro area | region X-ray diffractometer 11, 13, 15 Holder 12, 14, 16 Pulse motor 17 PSPC
18 Opening 19 X-ray tube F X-ray source L Sample axis R X-ray S Sample W Mosaic angle width O X-ray condensing point

Claims (4)

In an X-ray condensing apparatus for condensing characteristic X-rays emitted from an X-ray source,
A flat plate-shaped first flat plate monochromator disposed on the X-ray traveling path radiated from the X-ray source;
A flat plate-shaped second flat plate monochromator disposed downstream of the first flat plate monochromator with respect to the X-ray traveling path;
Wherein the first flat plate monochromator and the second flat monochromator are arranged in perpendicular position relative to each other, further wherein the first flat monochromator and a second flat monochromator, characterized in that it is formed by a mosaic crystal X-ray condensing device. In X-ray focusing device according to claim 1, mosaic angular width of the mosaic crystal, obtained when the mosaic crystal while applying a parallel X-ray beam on the mosaic crystal is rotated ω within a very small angle range An X-ray condensing device having a range of 0.3 ° to 1 ° when viewed at a ω angle of a diffraction line figure to be obtained. 3. The X-ray concentrating device according to claim 1, wherein the mosaic crystal forming the first flat plate monochromator and the second flat plate monochromator is formed of pyrolithic graphite. Line concentrator. In an X-ray condensing apparatus for condensing characteristic X-rays emitted from an X-ray source,
A first monochromator which is disposed on a traveling path of X-rays radiated from an X-ray source and is formed by bending a flat crystal so that its X-ray incident surface is concave;
A second monochromator that is disposed downstream of the first monochromator with respect to the X-ray traveling path and is formed by bending a flat crystal so that the X-ray incident surface is concave;
The first monochromator and the second monochromator are arranged such that their X-ray diffraction surfaces are perpendicular to each other,
The first monochromator and a second monochromator, X-rays condensing apparatus characterized by being formed by a mosaic crystal.

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