JP3098806B2 - X-ray spectrometer and EXAFS measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a curved crystal monochromator.
-Ray spectroscopy apparatus using the same and EXAF provided with the same
It relates to an S measuring device.

[0002]

2. Description of the Related Art EXAFS stands for Extended X-ray Absorption Fine Structure, which has a higher energy than the absorption edge of the constituent atoms of a crystal sample or an amorphous sample. The absorption fine structure observed over a range of about 1 keV. In order to measure the EXAFS, the ratio between the X-ray intensity before passing through the sample and the X-ray intensity after passing through the sample may be obtained by changing the X-ray energy (that is, the wavelength).

As an EXAFS measuring apparatus of this type, an apparatus using a curved crystal monochromator and a rotating anti-cathode X-ray tube is known. FIG. 4 shows a conventional EXAFS of this kind.
FIG. 4 is a plan view showing a spectroscopic mechanism of the measuring device. In this spectroscopic mechanism, the X-ray source, the curved crystal monochromator, and the light receiving slit are always located on a Rowland circle having a constant radius.
This is a mechanism that can change the wavelength of X-rays reaching the light receiving slit. Sliders 6, 8 are slidably attached to two orthogonal guides 2, 4, respectively. Both ends of a link 10 having a length of 2R are rotatably connected to the two sliders 6 and 8. Slider 8
, An arm 12 is rotatably connected, and its rotation center coincides with the rotation center of the slider 8 and the link 10. A guide 14 fixed to the arm 12 has a slider 1
6 is slidably connected. Midpoint O of link 10
, One end of a link R having a length R is rotatably connected, and the other end of the link 18 is rotatably connected to the slider 16. The slider 8 can be driven by a pulse motor 22 via a screw 20, and the slider 16 can be driven by a pulse motor 26 via a screw 24.

An X-ray focal point F is disposed at a position where the center lines of two orthogonal guides 2 and 4 intersect. The guides 2, 4 and the X-ray focus F are spatially stationary. The connection point M between the link 10 and the slider 8 has a curved crystal monochrome
The curved crystal monochromator is fixed to the link 10 so that the center of the motor is centered. The middle point O of the link 10 is
The center of the land circle 28. The reflection surface of the curved crystal monochromator is arranged along the Rowland circle 28.
The center of the light receiving slit is located at the connection point S between the link 18 and the slider 16, and the light receiving slit is fixed to the slider 16. A sample and an X-ray detector are arranged behind the light receiving slit, and these are all fixed to the slider 16.

The distance from the X-ray focal point F to the center M of the curved crystal monochromator is R1, and the curved crystal monochromator is
The distance from the center M of the data to the center S of the light receiving slit is R2
It is. In this spectroscopic mechanism, the pulse motors 22 and 26 are interlocked and controlled so that R1 and R2 become equal. And
By changing the values of R1 and R2, the angle of incidence of the X-rays incident on the curved crystal monochromator changes, whereby the wavelength of the X-rays reaching the light receiving slit changes. When R1 and R2 are changed, the center O of the Rowland circle 28 moves in space, but the radius R of the Rowland circle 28 is constant.

[0006]

The conventional X-ray spectrometer described above requires control of two pulse motors in order to change the wavelength of X-rays, and has a complicated structure and control. When the wavelength is changed, the slider 8 moves, the angle of the arm 12 with respect to the slider 8 changes, and the position of the slider 16 with respect to the guide 14 also changes, so that the slider 16 draws a complicated trajectory.
Since the sample and the X-ray detector are fixed to the slider 16, if the slider 16 draws a complicated trajectory, there are the following disadvantages. That is, in this type of EXAFS measurement apparatus, a semiconductor detector is often used as an X-ray detector. However, since the semiconductor detector is heavy, when the slider 16 on which it is mounted draws a complicated trajectory, the spectrometer is used. It is necessary to increase the stiffness of each mechanism that constitutes. When the Roland circle 28 is in a horizontal plane, the weight of the semiconductor detector can be supported by, for example, floating the slider 16 with an air bearing. In order to support the weight of the vehicle, a very large load is applied to each mechanism.

An object of the present invention is to provide an X-ray spectrometer and an EXAFS measuring apparatus in which the driving source of the spectroscopic mechanism can be made one and the movements of the sample and the X-ray detector are not so complicated. .

[0008]

The X-ray spectrometer according to the first invention has the following configuration. (A) A parallel four-bar mechanism in which the lengths of the four links are equal to each other. (B) A stationary joint of the parallel four-bar mechanism is defined as a first link, a link parallel to the first link is defined as a third link, and two links connecting the first link and the third link are defined as a second link. And the fourth link are defined as the first connection, the connection connecting the first link and the second link, the second connection, the connection connecting the second link and the third link, and the third link and the fourth link. An X-ray source arranged at the position of the first treatment, where the treatment for connecting the links is defined as a third treatment, and the treatment for connecting the fourth link and the first link is defined as a fourth treatment. (C) A curved crystal monochromator arranged at the third facing position and fixed to the third link. (D) a slider that moves along a straight line passing through the first encounter and perpendicular to the first link. (E) It has the same length as each link of the parallel four-bar mechanism, and has one end rotatably connected to the second treatment and the other end rotatably connected to the slider via the fifth treatment. Fifth link. (F) A light receiving slit arranged at the fifth facing position.

According to a second aspect of the present invention, there is provided the X-ray spectrometer according to the first aspect, wherein any one of the rotational movement of the second link, the rotational movement of the fourth link, and the linear movement of the slider is used as a drive source. It is characterized in that the node mechanism is moved to change the wavelength of X-rays reaching the light receiving slit.

[0010] In a third aspect of the present invention, the above-mentioned X-ray spectrometer is provided by EX.
It is mounted on an AFS measurement device.

According to a fourth aspect of the present invention, in the third aspect, the first arm is arranged so as to always be located on a straight line passing through the first and third encounters, and the fifth arm is always arranged in the fifth arm. A second arc arranged to be located on a straight line passing through the third and third treatments
An X-ray tube and a divergence slit are fixed to a first arm, and a light receiving slit, a sample, and an X-ray detector are fixed to a second arm.

[0012]

The X-ray spectrometer and the EXAFS measuring apparatus of the present invention are characterized by their spectroscopic mechanisms. In particular, they employ a parallel four-bar mechanism and one slider mechanism and make the X-ray source rotatable. As a result, only one drive source for the spectroscopic mechanism is required. In the conventional spectroscopic mechanism shown in FIG. 4, the direction from the X-ray source toward the curved crystal monochromator is spatially fixed, and the X-ray tube may be fixed. Instead, two pulse motors are used. Interlocking control was required. On the other hand, in the present invention, the rotation of the X-ray source is required, but since only one drive source is required for the spectroscopic mechanism in principle, the entire mechanism is simplified. In addition, the slider moves over the spatially fixed guide and the center of the light receiving slit comes on this slider, so that the sample and the semiconductor detector do not move complicatedly even when changing the wavelength. Help me.

[0013]

FIG. 1 is a plan view of one embodiment of the X-ray spectrometer of the present invention. The spectroscopic mechanism of this spectroscopic device includes a parallel four-bar link mechanism, a slider mechanism, and the like, each link having the same length. The basic functions are the same as before,
An object of the present invention is to make it possible to change the wavelength of X-rays reaching the light receiving slit while always positioning the X-ray source, the curved crystal monochromator, and the light receiving slit on a Rowland circle having a constant radius.

The parallel four-bar mechanism comprises a first link 30, a second link 32, a third link 34, and a fourth link 36.
The length of each link is all R. Since the first link 30 is a stationary node, it can be replaced by a frame of the apparatus. The guide 38 is arranged along a straight line orthogonal to the first link through the connection point F between the first link 30 and the second link 32. A slider 40 is slidably attached to the guide 38. At a connection point O between the second link 32 and the third link 34, one end of a fifth link 42 having a length R is rotatably connected, and the other end of the fifth link 42 is rotatably connected to the slider 40. It is.

The above is the configuration of the basic part of the spectral mechanism.
Explaining the relationship between this mechanism and various elements of the EXAFS measurement device, an X-ray focal point is arranged at a connection point F between the first link 30 and the second link 32, and the third link 34 and the fourth link 3
The center of the curved crystal monochromator is set at the connection point M of No. 6, and the center of the light receiving slit is set at the connection point S of the fifth link 42 and the slider 40. Then, a connection point O between the second link 32, the third link 34, and the fifth link 42
Is the center of the Rowland circle 28.

Next, the mounting state of various elements of the EXAFS measuring device will be described. The first arm 44 is a component for always indicating the direction from the point F to the point M (that is, the direction from the X-ray source to the curved crystal monochromator). First
One end of the arm 44 is rotatably connected to the point F, and the other end is slidably connected to the point M. An X-ray tube is fixed to the first arm 44. The second arm 46 is a component for always indicating the direction from the point M to the point S (that is, the direction from the curved crystal monochromator to the light receiving slit). 2nd arm 46
Has one end rotatably connected to point S and the other end slidably connected to point M. And this second
A light receiving slit is fixed to the arm 44.

FIG. 3 is a plan view showing such an attached state. An X-ray tube 48 and a diverging slit 50 are fixed to the first arm 44. X-ray tube 48 is a rotating anti-cathode X-ray tube. A light receiving slit 52, a sample 54, and an X-ray detector 56 are attached to the second arm 46. In this embodiment, a semiconductor detector is used as the X-ray detector 56. In addition, a partial transmission type ion chamber 58 is disposed between the light receiving slit 52 and the sample 54. The ion chamber 58 measures the intensity of the X-rays before passing through the sample, but may be omitted as described later. The curved crystal monochromator 60 is fixed to the third link 34. This curved crystal monochromator 60 has a reflection surface whose radius of curvature is R and whose reflection surface is
8 along. On the other hand, the radius of curvature of the crystal lattice plane is 2R. That is, a Johansson-type curved crystal monochrome meter is used.

Next, the operation of the EXAFS measuring apparatus will be described. The divergence angle of the X-rays emitted from the X-ray focal point F is restricted by the divergence slit 50 and is incident on the curved crystal monochromator 60 at an incident angle θ. Then, only X-rays of a predetermined wavelength are reflected at the reflection angle θ and converge on the light receiving slit 52. Sample 5
The intensity of the X-rays before passing through the X-ray 4 is measured by the ion chamber 58, and the intensity of the X-rays after passing through the semiconductor detector 56.
Is detected by Then, the absorption intensity of the sample at that wavelength can be obtained by calculating the X-ray intensity ratio between the two. The EXAFS pattern of the sample can be obtained by changing the incident angle θ and measuring the absorption intensity each time. When the ion chamber 58 is omitted, the X-ray intensity before and after transmission of the sample can be measured only by the semiconductor detector 56 by putting the sample 54 in and out of the X-ray optical path.

Next, a driving method of the spectroscopic mechanism shown in FIG. 1 will be described. In order to change the state of the spectral mechanism, the angle of the second link 32 with respect to the first link 30 of the parallel four-bar mechanism may be changed. Therefore, a turntable having the X-ray focal point F as the center of rotation may be provided, the second link 32 may be fixed to the turntable, and the turntable may be rotated by a pulse motor. FIG.
2 shows a rotary table 62 of this type. FIG.
Is a state where the spectroscopic mechanism shown in FIG. 1 is moved to another state.

By the way, besides the above-mentioned driving method, several methods equivalent to this are conceivable. For example, the following alternative driving method can be adopted. (A) The rotation angle of the fourth link 36 with respect to the first link 30 is changed. That is, the rotational movement of the fourth link 36 is used as a drive source. (B) The slide position of the slider 40 with respect to the guide 38 is changed. That is, the linear motion of the slider 40 is used as a drive source. However, in this case, the first link 32 and the fifth link
When the link 42 is on a straight line, the direction of movement of the mechanism is undefined. That is, when the slider 40 is driven toward the X-ray focal point F in this state, the first link 32 can rotate both clockwise and counterclockwise. Therefore, in this state, some auxiliary driving source is required.

The three driving methods described above, that is, the second driving method
The method of using any one of the link 32, the fourth link 36, and the slider 40 as a driving source is the simplest in structure since the pulse motor can be fixedly mounted on a frame or the like. Further, the rotational movement of the first arm 44 can be used as a drive source. However, if the pulse motor itself can be moved spatially, the following driving method can be employed. (C) A pulse motor is mounted on the first arm 44, and an arbitrary position in the longitudinal direction of the slide groove 45 of the first arm 44 is M
Control to match the point. (D) A pulse motor is mounted on the second arm 46, and an arbitrary position in the longitudinal direction of the slide groove 47 of the second arm 46 is set to M
Control to match the point.

In the apparatus of this embodiment, the light receiving slit 52
Of the sample 54 and the semiconductor detector 56 are not so complicated. That is, the linear motion along the guide 48 is mainly performed, and the
There is only a change in direction due to the rotational movement of.

When the EXAFS measuring apparatus shown in FIG. 3 is constructed upright, for example, the curved crystal monochromator 6
In the case of disposing the upper part 0 and the guide 38 shown in FIG. 1 below, the weight of the semiconductor detector 56 can be received by the spatially fixed guide 38.
A large load is not applied to other link mechanisms.

In the case of the vertical arrangement as described above, the sample can be held horizontally. That is, only the sample is fixed to the slider 40 instead of the second arm 46. At that time, the sample surface is turned upward. In this case,
EXAFS measurement is possible even with a liquid sample. However, since the thickness of the sample through which the X-rays pass changes with the movement of the spectroscopic mechanism, it is necessary to consider this correction when analyzing the EXAFS pattern. Also, the receiving slit,
All of the sample and the X-ray detector can be fixed to the slider 40.

[0025]

According to the present invention, a single driving source for the spectroscopic mechanism is required by adopting the parallel four-bar mechanism and one slider mechanism and arranging the X-ray source rotatably. . In addition, since the slider moves over the spatially fixed guide and the center of the light receiving slit comes on this slider, the sample and the semiconductor detector do not move complicatedly even when changing the wavelength. Yes. Therefore, EXAF
It is also possible to arrange the S apparatus vertically, in which case the sample can be kept horizontal.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of an X-ray spectrometer of the present invention.

FIG. 2 is a plan view showing another state of the apparatus of FIG. 1;

FIG. 3 is a plan view of an EXAFS measurement device provided with the X-ray spectrometer of FIG. 1;

FIG. 4 is a plan view of a conventional X-ray spectrometer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 30 first link 32 second link 34 third link 36 fourth link 38 guide 40 slider 42 fifth link 44 first arm 46 second arm 48 X-ray tube 50 divergence slit 52 light receiving slit 54 sample 56 semiconductor Detector 60 Curved crystal monochromator F X-ray focal point M Center of curved crystal monochromator S Center of light receiving slit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 23/00-23/227 G21K 1/06

Claims (4)

(57) [Claims] 1. An X-ray spectrometer having the following configuration. (A) A parallel four-bar mechanism in which the lengths of the four links are equal to each other. (B) A stationary joint of the parallel four-bar mechanism is defined as a first link, a link parallel to the first link is defined as a third link, and two links connecting the first link and the third link are defined as a second link. And the fourth link are defined as the first connection, the connection connecting the first link and the second link, the second connection, the connection connecting the second link and the third link, and the third link and the fourth link. An X-ray source arranged at the position of the first treatment, where the treatment for connecting the links is defined as a third treatment, and the treatment for connecting the fourth link and the first link is defined as a fourth treatment. (C) A curved crystal monochromator arranged at the third facing position and fixed to the third link. (D) a slider that moves along a straight line passing through the first encounter and perpendicular to the first link. (E) It has the same length as each link of the parallel four-bar mechanism, and has one end rotatably connected to the second treatment and the other end rotatably connected to the slider via the fifth treatment. Fifth link. (F) A light receiving slit arranged at the fifth facing position. 2. The method according to claim 1, wherein one of the rotational movement of the second link, the rotational movement of the fourth link, and the linear movement of the slider is used as a driving source to move the parallel four-bar mechanism, and the X-rays reaching the light receiving slit are thereby reduced. The X-ray spectrometer according to claim 1, wherein the wavelength is changed. 3. An EXAFS measurement apparatus comprising the X-ray spectrometer according to claim 1. 4. A first arm, which is always positioned on a straight line passing through the first and third encounters, and always passes through the fifth and third encounters. An X-ray tube and a divergence slit are fixed to the first arm, and a light receiving slit, a sample, and an X-ray detector are fixed to the second arm. 4. The EXAFS measuring apparatus according to claim 3, wherein?