JPH01133000A - Non-planar spectrocrystal - Google Patents

Abstract

PURPOSE:To take out outgoing X-ray in a constant direction while easing the setting of angle of diffraction by grinding either a first spectrocrystal or a second spectrocrystal of a channel cut spectroscope or both surface in non-planar form. CONSTITUTION:X-rays having serial spectra generated from an X-ray generator 1 perform incidence into a spectrocrystal 2, only a part of X-rays which have prescribed wave length is diffracted and the other X-rays having the other wave length are absorbed in the spectrocrystal 2. Diffracted X-rays enter into a spectrocrystal 3 and guided in a measuring device 4 after diffraction. The spectrocrystals 2, 3 are fixed on a crystal holder 5 and at the crystal holder 5 angle of diffraction is set by a rotating mechanism 7 to which a rotating angle read-out mechanism (encoder) 6 is attached. The spectrocrystals 2, 3 are cut off from a monocrystal and the crystal surface of the spectrocrystals 2, 3 is automatically maintained parallel. The position of outgoing X-ray taken out from the spectroscope can be maintained constant by grinding either the spectrocrystal 2 or the spectrocrystal 3 or both.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a non-planar structure that can simplify the drive mechanism, stabilize the exit position of the emitted X-rays, and simplify the optical axis adjustment of the channel-cut spectrometer. It concerns spectroscopic crystals.

[Conventional technology]

In recent years, there has been an increasing demand for atomic-level structural analysis of amorphous materials. Among these, structural analysis using X-rays is attracting particular attention. This type of analysis is performed by varying the wavelength of X-rays within a certain range and measuring quantities such as X-ray transmittance, fluorescent X-ray yield, or X-ray photoelectron yield for each wavelength.

Commonly used X-ray sources include electron beam-excited X-ray generators with a relatively low output intensity on a laboratory scale, or synchrotron radiation sources with a large output intensity on a large scale. In the case of any of the X-ray sources, the obtained X-rays have a continuous spectrum, so a technique for spectrally dispersing only the X-rays of desired wavelength components is required.

In order to improve measurement accuracy and simplify handling, the content of harmonic components is small, and the position of the X-rays extracted from the spectrometer (outgoing X-rays) can be kept constant regardless of the wavelength of the outgoing X-rays. The development of spectroscopic optical systems is urgently needed.

Next, the operating principle of the channel-cut spectrometer will be briefly described. In FIG. 3, continuous X-rays generated from the X-ray diffraction by crystal is Bragg
According to the law of
When the wavelength of the X-ray diffracted in the direction of the second spectroscopic crystal 3 is λ, 2dsinθ=nλ (1) holds between them. Here, n is a natural number called the order of Bragg. In the case of a single-crystal spectrometer that uses only one spectroscopic crystal as described above, the output (diffraction) from the first spectroscopic crystal 2
The emission direction of the X-rays changes each time θ is changed, which significantly limits the structure of the measurement system. Furthermore, a single crystal spectrometer generally includes X-rays of a desired wavelength, that is, X-rays when n≧2 in equation (1) in addition to the case where n=1 in equation (1).

It often introduces systematic errors in the measurement data.

In order to eliminate some of these drawbacks, a second spectroscopic crystal 3 is installed. When the distance between the first dispersing crystal 2 and the second dispersing crystal 3 is L, and the angle of incidence of the X-ray with respect to the crystal plane is θ, the X-ray emitted from the channel cut spectrometer is parallel to the incident X-ray, Moreover, it is emitted with a distance D=2Lcosθ (2) shifted from the extension line of the incident X-ray. Since the X-rays emitted from the channel-cut spectrometer are always parallel to the incident X-rays, restrictions on the structure of the measurement system are significantly relaxed compared to when a single crystal spectrometer is used.

Every time the incident angle θ of the X-rays to the first spectroscopic crystal 2 is changed, the position of the measuring instrument must be translated in accordance with equation (2).

In order to keep the position of the emitted X-rays taken out from the spectrometer constant even if the incident angle θ to the first spectroscopic crystal 2 is changed,
It is customary to use a two-crystal spectrometer as shown in FIG. However, in this case, the position of the second crystal in the X direction is
0. It had to be controlled with a certain level of accuracy and within several angle seconds of the angle of the second spectroscopic crystal, and a large-scale driving device was required. In addition, as a literature related to the above-mentioned device, Review of Scientific Instruments (Rev, Sci, In5tr,), 53
, Q. Yu, (1982) pp. 22-33.

[Problem that the invention seeks to solve]

In the above conventional technology, when obtaining monochromatic X-rays from continuous X-rays, the crystal plane of the first dispersing crystal and the crystal plane of the second dispersing crystal are always parallel, and in a channel-cut spectrometer with a simple driving mechanism, one The position of the emitted X-rays taken out from the spectrometer changes each time the incident angle θ of the incident X-rays to the crystal plane of the first spectroscopic crystal changes, and the position of the measuring instrument is changed to follow this change. The problem was that it had to be done. In addition, in a two-crystal spectrometer whose main purpose is to keep the position of the emitted X-rays unchanged, the position of the second dispersing crystal is controlled, and the crystal plane of the second dispersing crystal is set to the first dispersing crystal. It is necessary to provide a mechanism for parallelizing the crystal plane of the crystal, which poses a problem in that the drive mechanism becomes complicated.

The purpose of the present invention is to ensure that the output X-rays extracted from the spectrometer with only a simple drive mechanism, such as a channel-cut spectrometer, are
The object of the present invention is to obtain a non-planar channel cut spectrometer that can always be taken out in a fixed direction without being affected by the incident angle.

[Means for solving problems]

The above object is achieved by grinding the surface of one or both of the first analyzing crystal and the second analyzing crystal into a non-planar shape in the channel cut spectrometer.

[Effect]

In the spectroscopy crystal of the present invention, one
Since a set of spectroscopic crystals is used, the crystal plane of the first spectroscopic crystal and the crystal plane of the second spectroscopic crystal are automatically kept parallel. Therefore, the diffraction angle can be set using only one drive mechanism, instead of the three systems of drive mechanisms that were required in the conventional two-crystal spectrometer. Further, by grinding one or both surfaces of the first spectroscopic crystal and the second spectroscopic crystal to a non-planar surface, the position of the emitted X-rays taken out from the spectrometer can be kept constant.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 is a block diagram of a spectrometer using an embodiment of a non-planar spectroscopic crystal according to the present invention, and Fig. 2 is a diagram showing the shape of the above embodiment, where (a) is a front view and (b) is a side view. It is a diagram. In FIG. 1, X-rays having a continuous spectrum generated from an X-ray source 1 are incident on a first spectroscopic crystal 2, and a part of the X-rays, that is, an X-ray having a wavelength satisfying Bragg's equation (1)
Only the lines are diffracted.

X-rays having other wavelength components are absorbed by the first spectroscopic crystal 2. The diffracted X-rays enter the second spectroscopic crystal 3, undergo one diffraction, and then are guided to the measuring device 4.

The first spectroscopic crystal 2 and the second spectroscopic crystal 3 are fixed to a crystal holder 5, and the crystal holder 5 has a rotation angle reading mechanism (
In this embodiment, the rotational center of the rotational mechanism 6 is set at the center of the diffraction surface 7 of the first spectroscopic crystal 2. The shape of the spectroscopic crystal is as shown in FIGS. 2(a) and (b). The diffraction surface 8 of the second spectroscopic crystal 3 is in the coordinate system shown in FIG.

x('P)=L/5in(W) (3
)z (y)=-L/cos(y) (
4) It is ground to T≦45＠, and in this example, L=20.

In Figure 1, the angle of incidence of X-rays on the spectrometer is set to 4.
When setting θ to be an angle of 5 degrees or less, the X-rays diffracted by the first spectroscopic crystal 2 are reflected at the point X(θ)=L/5in(θ)(5 ) 2(θ)-L/cos(θ) (6). Therefore, the distance between the X-ray diffracted by the second spectroscopic crystal 3 and guided to the measuring instrument and the extension line of the incident X-ray is I)=J x(θ)"+z(θ)"X5in(2 =2
L (7), which is independent of θ, that is, constant.

According to this embodiment, the diffraction angle can be set using only one drive mechanism, and the position of the emitted X-rays can be kept constant, resulting in cost reduction and man-hour reduction. In addition, since the crystal planes of the first dispersing crystal 2 and the second dispersing crystal 3 are always parallel, it is much easier to adjust the optical axis, especially the tilt angle, compared to a normal two-crystal spectrometer. There is also the effect that it can be done.

〔Effect of the invention〕

As described above, the non-planar spectroscopic crystal according to the present invention is a non-planar spectroscopic crystal for a channel-cut spectrometer that is ground from a single single crystal, and the first spectroscopic crystal is placed on an incident X-ray beam generated from an X-ray generator. A second dispersing crystal is disposed on the X-ray diffracted by the first dispersing crystal, and one or both surfaces of the first dispersing crystal and the second dispersing crystal are formed into a non-flat surface. Since the crystal planes of the first and second spectroscopic crystals are always parallel, it is not only easy to set the diffraction angle, but also three systems of drive are required to set one diffraction angle with conventional two-crystal spectrometers. There is only one mechanism
This is possible with two drive mechanisms, and the output position of monochromatic X-rays taken out from the spectrometer can be kept constant, making it easy to adjust the optical axis and reducing the manufacturing cost of the spectrometer. can.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a spectrometer using an embodiment of a non-planar spectroscopic crystal according to the present invention, and Fig. 2 is a diagram showing the shape of the above embodiment, where (a) is a front view and (b) is a side view. 3 are diagrams showing the principle of a channel-cut spectrometer, and FIG. 4 is a diagram showing the operation of a two-crystal spectrometer. 1...X-ray generator! 2...First spectroscopic crystal 3...
2nd Spectroscopic Crystal Representative Patent Attorney Junnosuke Nakamura Figure 1 Figure 2 Figure I: X-ray inspiration purchase 2-year-old 1 minute υ table crystal 3;

Claims (1)

[Claims] 1. In a non-planar spectroscopic crystal of a channel-cut spectrometer that is ground from a single single crystal, a first spectroscopic crystal is placed on an incident X-ray beam generated from an X-ray generator, and diffraction by the first spectroscopic crystal is performed. A non-planar spectroscopic crystal, characterized in that a second spectroscopic crystal is disposed on the X-ray, and one or both of the first and second spectroscopic crystals have a non-planar surface.