JP2003107021A - Fluorescent x-ray analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small and low cost fluorescent X-ray analyzer in which analysis can be conducted in a short time from a light element to a heavy element. SOLUTION: The fluorescent X-ray analyzer comprises a spectroscopic element 6 and a means 10 for rotating a detector 8 at an angular velocity ratio of 1:2. A semiconductor detector 8 cooled by a Peltier element is employed as the detector 8 and an artificial multilayer film lattice having a constant lattice plane interval where two elements having different atomic numbers are laid in multilayer is employed as the spectroscopic element 6 without providing an exchanger for exchanging the spectroscopic element 6.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fluorescent X-ray analysis apparatus.

[0002]

2. Description of the Related Art In a conventional so-called wavelength dispersive X-ray fluorescence analyzer, a gas flow type proportional counter (FP) is used as a detector, for example, for the analysis of elements lighter than Al.
For C), a scintillation counter (SC) is used for analysis of elements heavy such as Fe, Sn, etc., and an optical system such as a spectroscopic element suitable for each detector is combined for spectral analysis.

However, in such an apparatus, since at least two types of detectors must be provided, the structure is complicated, and the characteristics of the detector, such as low energy resolution,
Since the sensitivity and accuracy of the equipment are not always sufficient, another accurate analysis cannot be performed. On the other hand, in the conventional so-called energy dispersive X-ray fluorescence analyzer, a semiconductor detector (SSD) with high energy resolution is used, but a large cooling device is often required for the detector, which makes scanning difficult. Since the spectroscopic element is not used, the resolution of the device determines the resolution of the detector. Here, in general, the resolution of a fluorescent X-ray analyzer is superior to that of a wavelength dispersion type using an appropriate spectroscopic element for the analysis of elements that are as light as Al and Fe.
The energy dispersive type using a semiconductor detector is excellent in the analysis of elements that are heavier than a certain degree. Therefore, in conventional energy dispersive X-ray fluorescence analyzers, Al and Fe
The accuracy of the device is not always sufficient for the analysis of moderately light elements, and it is still not possible to perform accurate analysis.

Therefore, an X-ray fluorescence analyzer using only a semiconductor detector as a detector has been proposed (Japanese Patent Laid-Open No. 200-200200).
0-329714).

[0005]

However, since the analyzer is equipped with a crystal exchanger for rotating and exchanging crystals, the structure of the device is complicated, which causes a large size and high cost. . In addition, when analyzing both light elements and heavy elements, it is necessary to rotate (scan) both the spectroscopic element and the semiconductor detector over a wide angle range before and after replacing the crystal. Therefore, the measurement time becomes long.

Therefore, an object of the present invention is to provide a fluorescent X-ray analyzer which is small in size, low in cost, and capable of analyzing light elements to heavy elements in a short time.

[0007]

In order to achieve the above object, an X-ray fluorescence analyzer of the present invention comprises a spectroscopic element and a rotating means for rotating a detector at an angular velocity ratio of 1: 2. Fluorescent X
In the line analysis device, a semiconductor detector that is cooled by a Peltier element is used as the detector, and a multi-layered structure of two elements having different atomic numbers is provided as the spectroscopic element without providing an exchanger for exchanging the spectroscopic element. It is characterized in that an artificial multi-layered film lattice having a fixed lattice plane interval is adopted.

According to the present invention, first of all, the crystal exchanger is not provided and only the semiconductor detector is used as the detector, so that the structure is remarkably simplified. In the analysis of elements as light as Al and Fe, the artificial multi-layered film lattice is used, so that excellent resolution can be obtained due to the dispersive ability of the artificial multi-layered film lattice. On the other hand, in the analysis of elements heavier than Mo, since the semiconductor detector is used, the resolution is also excellent. Therefore, highly accurate and sufficiently accurate analysis from light elements to heavy elements becomes possible.

[0009]

DETAILED DESCRIPTION OF THE INVENTION An apparatus according to an embodiment of the present invention will be described below with reference to the drawings. First, the configuration of this device will be described. This apparatus passes a sample table 2 on which a sample 1 is placed, an X-ray source 4 such as an X-ray tube for irradiating the sample 1 with primary X-rays 3, and a fluorescent X-ray 5 generated from the sample 1. It is provided with a solar slit 11. In addition, the present device is provided in the optical path of the fluorescent X-rays 13 passing through the solar slits 11, and the spectroscopic element 6 that disperses the incident fluorescent X-rays 13,
A semiconductor detector 8 for measuring the intensity of the fluorescent X-ray 7 dispersed by the spectroscopic element 6. Further, the present apparatus changes the wavelength of the fluorescent X-rays 7 dispersed by the spectroscopic element 6 so that the spectroscopic X-rays 7 are incident on the semiconductor detector 8, and the spectroscopic element 6 and the semiconductor detector 8 are arranged. A rotating means 10 for rotating in an interlocking state is provided.

As the X-ray source 4, it is preferable to use an air-cooled X-ray tube from the viewpoint of miniaturization, and in the present embodiment, a small X-ray tube of about 50 W can be used.

The semiconductor detector 8 is, for example, a silicon drift detector (SDD) that is cooled by a Peltier element instead of liquid nitrogen.

The rotating means 10 is a so-called goniometer, which separates the spectroscopic element 6 and the semiconductor detector 8 from the point O at an angular velocity ratio of 1: 2.
To rotate around. When the fluorescent X-ray 13 enters the spectroscopic element 6 at an incident angle θ, the fluorescent X-ray 13
The extension line 9 and the fluorescent X-ray 7 which is spectrally (diffracted) by the spectroscopic element 6 form a spectral angle 2θ which is twice the incident angle θ, but the rotating means 1
0 changes the spectroscopic element 6 of the spectroscopic element 6 so that the spectroscopic fluorescent X-ray 7 is incident on the semiconductor detector 8 while changing the spectral angle 2θ and changing the wavelength of the spectroscopic X-ray 7. The semiconductor detector 8 is rotated (scanned) along the circle 12 about the axis O by twice the rotation angle of the axis O which is perpendicular to the plane of the paper passing through the center of the surface.

The rotating means 10 mechanically connects the spectroscopic element 6 and the semiconductor detector 8 with a drive mechanism such as a gear mechanism, and drives the gear mechanism with a drive source such as a single motor. Alternatively, the spectroscopic element 6 and the semiconductor detector 8 may be driven by independent driving sources and driving mechanisms, and the driving sources may be appropriately controlled to realize the above-described operation.

Here, as the spectroscopic element 6, an artificial multilayer film lattice 6 in which a large number of two elements having different atomic numbers are laminated is used. As shown in FIG. 1 (b), the artificial multilayer film lattice 6
Have a constant lattice spacing d.

The artificial multilayer lattice 6 is formed by repeatedly laminating a large number of first layers 61 and second layers 62. First
The layer 61 has a reflection surface 60 that reflects a part of the fluorescent X-rays 13, and the first element having an atomic number of 42 or more (for example, molybdenum Mo (42), tungsten W (74), rhenium Re ( No. 75)), and is generally formed as a single body. On the other hand, the second layer 62 has a second atomic number of 14 or less.
Elemental simple substance (for example, beryllium Be (No. 4), carbon C (No. 6), silicon Si (No. 14), etc.) and compound (B
₄ C) formed. Note that, in general, W and C or Si
It is preferred to use a combination of

The thickness of the second layer 62 is the same as that of the first layer 61.
It is generally preferable to set the thickness to about 3 times, and at least twice the thickness. As a result, a sufficient lattice spacing d is obtained and X due to an element with a large atomic number
This is to reduce the absorption of the lines 13 and 7 as much as possible.

Next, the operation of this device will be described.
From the X-ray source 4 to the primary X-ray 3 on the sample 1 placed on the sample table 2.
Is irradiated, the fluorescent X-rays 5 generated from the sample 1 pass through the solar slit 11 and are dispersed by the artificial multilayer film grating 6, and the intensity of the dispersed fluorescent X-rays 7 is measured by the semiconductor detector 8. . Here, by rotating the spectroscopic element 6 and the semiconductor detector 8 in conjunction with each other by the rotating means 10, the fluorescent X-rays 5 generated from the sample 1 are allowed to pass through the solar slit 11, and first the spectroscopic element 6 respectively. Of the wavelength, and further separated electrically in detail by the semiconductor detector 8 having a high energy resolution and a wave height analyzer (not shown) for detection.

The artificial multilayer film grating 6 disperses the fluorescent X-rays 13 according to the following Bragg's equation. 2dsin θ = nλ d: lattice spacing, θ: incident angle, λ: wavelength

Therefore, by setting the lattice spacing d within a predetermined range, the incident angle θ has an appropriate value in relation to the wavelength of the X-ray to be spectrally separated. That is, in general, the lattice spacing d is preferably 10 to 100 angstroms, and more preferably 20 to 40 angstroms, so that the incident angle θ is in the range of 0 ° to 60 °. as a result,
As the range of rotation for scanning becomes narrower, X-ray fluorescence 1
In light element analysis with a long wavelength of 3, the incident angle θ
Becomes larger and an appropriate dispersibility is obtained.

On the other hand, since the incident angle θ in the heavy element analysis is extremely small, the artificial multi-layered lattice 6 has a low wavelength dispersion ability. However, for heavy elements, the semiconductor detector 8 has excellent resolution due to energy dispersion, and thus high analysis accuracy can be obtained.

In the apparatus of the above embodiment, the parallel optical system in which the solar slit 11 and the flat plate-shaped spectroscopic element 6 are combined is used, but the combination of the pinhole or linear hole slit and the curved spectroscopic element is concentrated. An optical system may be used. When the so-called Roland circle is not moved in the case of using the concentrated optical system, the rotating means needs to rotate the slits in conjunction with each other.

[0022]

As described above in detail, according to the present invention, the crystal exchanger is not required, so that the structure of the apparatus is remarkably simplified. In particular, it is possible to analyze light elements to heavy elements by scanning the artificial multilayer lattice and the semiconductor detector only once by the rotating means, and therefore the analysis time is shortened. Further, since the lattice plane spacing of the artificial multi-layered film lattice is much larger than that of the dispersive crystal, the rotation angle becomes smaller, and the analysis time becomes shorter. In addition, for light elements, the resolution of the semiconductor detector is low, whereas the wavelength λ of such fluorescent X-rays of light elements is long, so the angle of incidence θ is large, and therefore the wavelength is sufficiently dispersed by the artificial multilayer film grating. Since it is obtained, highly accurate analysis becomes possible. On the other hand, for heavy elements, since the incident angle θ is small, the spectra are close to each other, so that the dispersive power of the artificial multilayer lattice is low, but a high resolution can be obtained by the semiconductor detector.

Moreover, by using an artificial multi-layered film lattice having a large atomic number of an element in the reflective layer, the X-ray reflectance is improved about 10 times that of the crystal, so that the X-ray intensity of the X-ray source is small. Also improves analysis accuracy and sensitivity.

Furthermore, since the structure of the tip portion of the X-ray tube becomes compact by adopting the air-cooled X-ray tube,
It is possible to bring the X-ray tube close to the sample. Therefore, the device becomes extremely compact.

[Brief description of drawings]

FIG. 1 is a schematic view showing an X-ray fluorescence analyzer according to an embodiment of the present invention and an enlarged sectional view of an artificial multilayer film lattice.

[Explanation of symbols]

1 ... Sample, 2 ... Sample stage, 3 ... Primary X-ray, 4 ... X-ray source, 5
... Fluorescent X-rays generated from the sample, 6 ... Spectroscopic element, 7 ... Fluorescent X-rays dispersed by the spectroscopic element, 8 ... Semiconductor detector, 10 ...
Rotating means, 11 ... Slit, 13 ... Fluorescent X-ray passing through the slit.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) G21K 1/06 G21K 1/06 T

Claims (3)

[Claims] 1. A sample table on which a sample is placed, an X-ray source for irradiating the sample with primary X-rays, a slit for passing fluorescent X-rays generated from the sample, and a fluorescent X-ray passing through the slit. A spectroscopic element that is provided in the optical path for spectroscopically incident fluorescent X-rays, a detector that measures the intensity of the fluorescent X-rays that are spectroscopically dispersed by the spectroscopic element, and a wavelength of the fluorescent X-rays that is spectroscopically spectroscopically dispersed However, in a fluorescent X-ray analyzer including the spectroscopic element and a rotating unit that rotates the detector at an angular velocity ratio of 1: 2 so that the spectral X-ray fluorescence is incident on the detector. A semiconductor detector that is cooled by a Peltier element is used as the detector, and a plurality of layers of two elements having different atomic numbers are stacked as the spectroscopic element without providing an exchanger for exchanging the spectroscopic element. Artificial poly with lattice spacing An X-ray fluorescence analyzer characterized by employing a layered film lattice. 2. The artificial multilayer film lattice according to claim 1, wherein the artificial multilayer film lattice includes a first layer containing a first element having an atomic number of 42 or more and a second layer having an atomic number of 14 or less. A plurality of layers are alternately laminated, the lattice plane spacing d of the artificial multilayer lattice is set to 20 to 40 angstroms, and the thickness of the second layer is equal to the thickness of the first layer. An X-ray fluorescence analyzer set to double or more. 3. The fluorescent X-ray analyzer according to claim 1, wherein an air-cooled X-ray tube is used as the X-ray source.