JPH0432603Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an X-ray analysis device that can remove background noise.

When a sample such as a polycrystalline sample of metal or the like is irradiated with X-rays of a specific wavelength from a certain direction, the direction is set under Bragg diffraction conditions (2dsinθ=nλ, d: crystal lattice spacing, θ: irradiation angle, n: integer , λ: wavelength of irradiated X-rays), diffracted X-rays are generated. Therefore, by arranging the sample and the detector coaxially and rotating them at a speed of 1:2, the angle (θ) at which the diffraction A diffractometer method is known in which a substance is identified by determining the lattice spacing d, or the substance is quantified from the intensity of diffracted X-rays.

When carrying out such an X-ray diffraction method, it is desirable that the irradiated X-rays have a single wavelength. However, the wavelength of X-rays emitted from commonly used X-ray tubes is not single, and there are strong X-rays with a sharp peak at the wavelength specific to the target material of the X-ray tube, so-called Kα rays, and weaker but still strong X-rays. There are characteristic X-rays such as peak-like Kβ rays and continuous X-rays.
Generally, only the Kα rays are extracted using a filter, etc., and irradiated onto the sample, but it is impossible to completely unify the Kα rays. Therefore, for Kα rays, there is a range of diffraction angles within which no diffracted X-rays should exist. However, it is detected as noise. Furthermore, even if a sample is irradiated with X-rays of a completely single wavelength, X-rays other than diffracted X-rays, such as fluorescent X-rays and scattered X-rays, enter the detector from the sample and become noise, resulting in erroneous observations. It was the cause of

In such cases, a method is known in which a double filter is used to detect only Kα rays. This method will be explained using the absorption curve shown in FIG. In the periodic table, the ratio of the absorption coefficients of two adjacent elements, such as cobalt and nickel, is almost constant outside the absorption edge region, λ ₁ to λ ₂ , of two elements such as cobalt and nickel. _cp /μ _Ni≈0.9 . Now, if we make two filters containing cobalt with a weight of P (g/cm ² ) and nickel with a weight of 0.9P per unit area, these two filters will be
The absorption of the two filters is the same for X-rays outside λ ₁ to _{λ 2} , but between λ ₁ and λ ₂ , the absorption of the nickel filter is very weak and the absorption of the cobalt filter is very strong. If measurements are made using the same X-ray source using a nickel filter and a cobalt filter separately, the difference in values between the two will represent the effect only from the spectral band λ ₁ to _{λ 2} . If a copper anticathode is used as an X-ray source, the above spectral band will consist mostly of CuKα rays (λ0) and only a very weak base. Therefore, the nickel-cobalt double filter is
It can be seen that CuKα rays can be separated. However, 2
When using heavy filters, measurements had to be taken twice before and after using each filter.

The purpose of this invention is to perform X-ray analysis that can continuously obtain diffracted X-rays of a constant wavelength corresponding to the incident angle of each X-ray in a single observation using an X-ray analyzer using the diffractometer method. The goal is to provide equipment.

In order to achieve the above object, the X-ray analyzer according to the present invention has an X-ray tube that irradiates the sample with X-rays, and a detection part whose front center is vertically aligned in order to receive diffracted X-rays generated at the same diffraction angle. Rotating the sample about an axis that passes through the intersection of an X-ray detector having first and second detection sections adjacent to each other on a line and incident X-rays from the X-ray tube. The detector is supported so that the central axis is aligned with the central axis, the detector is oriented toward the central axis, and the line is parallel to the central axis, and the sample surface and the detector are moved at a speed of 1:2. and a first member arranged in front of the first detection part of the detector and formed of a member whose absorption edge wavelength of X-rays is slightly shorter than the wavelength of the characteristic X-rays of the X-ray tube. a second filter disposed in front of the second detection section of the detector and formed of a member slightly longer than the wavelength of the X-rays;
a filter; first and second scalers that coefficient the pulse signals sent from the first and second detection sections; and receiving the outputs of the first and second scalers and sending out the difference therebetween. It consists of a computing unit.

The first or second filter can be supported so that its angle with respect to the incident direction of X-rays can be adjusted.

The present invention will be explained in more detail below with reference to the drawings and the like.

Fig. 2 is a configuration diagram showing an embodiment of the X-ray analyzer according to the invention, Fig. 3 is a front view showing an embodiment of the coefficient tube according to the invention, and Fig. 4 is a detailed view showing the filter section of the counter tube. be.

The sample 1 and the counter tube 2 are mounted on a θ rotary table 3 and a 2θ rotary table 4, which are coaxially provided, respectively, and can be rotated at a speed ratio of 1:2. The central axis of rotation includes the intersection of the surface of the sample 1 and the incident X-rays from the X-ray tube 5. The X-rays generated from the X-ray tube 5 pass through the solar slit 6 on the incident radiation side, and then pass through the diverging slit 7.
The light enters the sample 1 in a divergent manner through the beam, and after being diffracted, it passes through the scattering slit 8 and the Solar slit 9 on the diffraction line side, and converges at the position of the light receiving slit 10. The solar slits 6 and 9 are made by layering a large number of thin metal plates stacked in parallel at narrow intervals, and can create a wide bundle of parallel wires.

Next, the configuration of the counter tube 2 will be explained with reference to FIGS. 3 and 4. The counter tube 2 includes detection parts 21 and 22, which are made by dividing an airtight container into two with a separating foil 23, so that the same diffracted X-rays occurring at the same diffraction angle can be independently detected.
Core wires 24 and 25 are stretched parallel to the optical axis, and a separation foil 23 is attached to a solar slit 9 in order to equalize the sensitivity of the two detection sections.
An adjustment screw 26 is provided that allows the counter tube 2 to be moved up and down so that it is located at the center. detection unit 21,
Filters 29 and 30 are arranged on the front surface of 22 with filter frames 27 and 28 interposed therebetween, and filter holders 31 and
It is fixed at 32. The filter frames 27 and 28 are pivoted on a shaft 33 that is on the same plane as the separating foil and perpendicular to the optical axis, and can be adjusted using tilt adjustment screws 34 and 35 so that the effective thicknesses of the filters 29 and 30 are equal. . For example, when the target of the X-ray tube 5 is copper, the filter 29 is made of nickel, a material whose X-ray absorption edge is slightly shorter than the wavelength of copper's characteristic X-rays (Kα rays), and the filter 30 is made of nickel, a material whose Cobalt, a material whose absorption edge for X-rays is slightly longer than the wavelength of the radiation, is used to form a double filter that separates CuKα radiation.

The pulse signals sent out from the detection units 21 and 22 are waveform-shaped by preamplifiers 11 and 12, and then counted by scalers 13 and 14, respectively, and then sent to a computing unit 15.
The difference between the outputs is calculated and the result is recorded on the recorder 16.

As explained in detail above, the X-ray analyzer according to the present invention supports the sample and the detector and rotates the sample and the detector at a speed of 1:2 with the axis including the intersection of the sample surface and the incident X-rays from the X-ray tube as the central axis. Since a coaxial rotation mechanism is used, diffracted X-rays of a constant wavelength can be continuously obtained corresponding to each incident angle.

Further, first and second scalers are used to count the pulse signals sent out from the first and second detection sections, and upon receiving the outputs of the first and second scalers, the difference between them is sent out from an arithmetic unit. Since it is configured to do so, it is possible to continuously extract only the necessary wavelength components.

Furthermore, since the inclination angle of the filter can be adjusted, the effective thickness of the filter can be easily made equal, allowing highly accurate observation.

[Brief explanation of the drawing]

Fig. 1 is a graph for explaining the double filter, Fig. 2 is a configuration diagram showing an embodiment of the X-ray analyzer according to the invention, and Fig. 3 is a front view showing an embodiment of the counter of the invention device. , FIG. 4 is a detailed view showing the filter section of the counter tube. 1...sample, 2...counter tube, 3...θ rotating table,
4... 2θ rotating table, 5... X-ray tube, 6, 9... Solar slit, 7... Diverging slit, 8... Scattering slit, 10... Light receiving slit, 11, 12...
...Preamplifier, 13, 14... Scaler, 15...
... Arithmetic unit, 16 ... Recorder, 21, 22 ... Detection section, 23 ... Separation foil, 24, 25 ... Core wire, 2
6... Vertical adjustment screw, 27, 28... Filter frame, 29, 30... Filter, 31, 32... Filter holder, 33... Shaft, 34, 35... Tilt adjustment screw.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An X-ray tube that irradiates a sample with X-rays and an X-ray tube that is arranged so that each center of the front surface of the detection section is adjacent to each other on a vertical line in order to receive diffracted X-rays generated at the same diffraction angle. An X-ray detector having a first and second detecting section provided therein, and an axis passing through the intersection of incident X-rays from the X-ray tube as the central axis, and the central axis of rotation of the sample is the central axis. a mechanism that rotates the sample surface and the detector at a speed of 1:2, supporting the detector so as to face the central axis and with the line parallel to the central axis, and rotating the sample surface and the detector at a speed of 1:2; arranged in front of the first detection section of the detector;
a first filter formed of a member whose absorption edge wavelength is slightly shorter than the wavelength of the characteristic X-ray of the X-ray tube;
a second filter formed of a member slightly longer than the wavelength of the line; first and second scalers that count pulse signals sent from the first and second detection sections; An X-ray analysis device comprising: a computing unit that receives the output of the second scaler and sends out the difference thereof. (2) The X-ray analysis apparatus according to item 1, wherein the first or second filter is supported so that its angle with respect to the incident direction of the X-rays can be adjusted.