JP2000329714A - X-ray fluorescence analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray fluorescence analyzer which uses only a semiconductor detector as a detector, whose constitution is simple, whose accuracy and sensitivity are high and which can perform a sufficiently precise analysis. SOLUTION: A sample base 2, an X-ray source 4, a slit 11 which passes fluorescent X-rays 5 generated from a sample 1 and the like are provided at this X-ray fluorescence analyzer. In addition, a spectral element exchanger 14 which comprises a plurality of kinds of spectral elements 6 so as to be selected and which spectrally diffracts fluorescent X-rays 13 is provided, and a semiconductor detector 8 which measures the intensity of spectrally diffracted fluorescent X-rays 7 is provided. In addition, an interlocking means 10 by which the spectral element exchanger 14 and the semiconductor detector 8 are interlocked in such a way that, while the wavelength of the spectrally diffracted fluorescent X-rays 7 is being changed, the spectrally diffracted fluorescent X-rays 7 are incident on the semiconductor detector 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray fluorescence analyzer using only a semiconductor detector as a detector.

[0002]

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

[0003]

However, in such an apparatus, since at least two types of detectors must be provided, the structure is complicated, and the sensitivity of the apparatus is low due to the characteristics of the detector such as low energy resolution. Since the accuracy is not always sufficient, accurate analysis cannot be performed. On the other hand, a conventional so-called energy dispersive X-ray fluorescence spectrometer uses a semiconductor detector (SSD) having a high energy resolution. However, a large-scale cooling device is required for the detector, which makes scanning difficult. Because there is no spectral element
The resolution of the device is determined by the resolution of the detector. Here, in general, the resolution of a fluorescent X-ray analyzer is excellent in the wavelength dispersion type using an appropriate spectroscopic element in the analysis of elements as light as Al or Fe, and in semiconductor analysis in the analysis of elements heavier than Mo or more. Energy dispersing type using a vessel is excellent. Therefore, in the conventional energy dispersive X-ray fluorescence spectrometer, the accuracy of the device is not always sufficient for the analysis of an element as light as Al or Fe, so that another accurate analysis cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a fluorescent X-ray analyzer which has a simple configuration using only a semiconductor detector as a detector and has high accuracy and sensitivity and can perform sufficiently accurate analysis. The purpose is to provide.

[0005]

In order to achieve the above object, an X-ray fluorescence spectrometer according to a first aspect of the present invention comprises a sample stage on which a sample is placed and an X-ray for irradiating the sample with primary X-rays. Source,
And a slit for passing fluorescent X-rays generated from the sample. A spectroscopic element exchanger that has a plurality of types of spectroscopic elements and selectively advances to an optical path of the fluorescent X-rays passing through the slit to split the incident fluorescent X-rays; A semiconductor detector for measuring the intensity of the line. Further, while changing the wavelength of the fluorescent X-rays split by the spectroscopic element, the slit, so that the split fluorescent X-rays are incident on the semiconductor detector.
There is provided interlocking means for interlocking at least the spectral element exchanger and the semiconductor detector among the spectral element exchanger and the semiconductor detector.

According to the first aspect of the present invention, first, only the semiconductor detector is used as the detector, so that the configuration is simple.
In addition, in the analysis of an element as light as Al or Fe while selecting an appropriate spectroscopic element and using it, it is excellent in resolution and Mo, while responding to fluorescent X-rays in a wide wavelength range by such interlocking means.
In the analysis of an element that is heavier than that, a semiconductor detector is used, so that the resolution is also excellent. Therefore, highly accurate and sufficiently accurate analysis can be performed.

[0007] The fluorescent X-ray analyzer according to the second aspect is the first aspect.
In the apparatus, a moving means for moving the semiconductor detector to a position where the intensity of the fluorescent X-ray generated from the sample is measured without passing through the slit and the spectral element.

According to the second aspect of the present invention, the X-rays generated from the sample can be directly incident on the semiconductor detector without passing through a slit or a spectroscopic element by the moving means. For example, even when the intensity of the fluorescent X-ray is weak, it can be measured at a high S / N ratio. Therefore, highly sensitive and sufficiently accurate analysis can be performed.

According to a third aspect of the present invention, there is provided an X-ray fluorescence spectrometer comprising: a sample stage on which a sample is placed;
It has a radiation source and a slit for passing fluorescent X-rays generated from the sample. In addition, a total reflection mirror that reflects a part of the fluorescent X-rays passing through the slit, and a semiconductor detector that measures the intensity of the fluorescent X-rays reflected by the total reflection mirror are provided. Further, changing the wavelength band of the fluorescent X-rays reflected by the total reflection mirror, the slit, so that the reflected fluorescent X-rays are incident on the semiconductor detector.
A rotation means for rotating at least the total reflection mirror among the total reflection mirror and the semiconductor detector is provided.

According to the third aspect of the present invention, the configuration is simple because only the semiconductor detector is used as the detector.
In addition, in the analysis of elements as light as Al and Fe while reflecting the fluorescent X-rays in a wide wavelength range by such a rotating means, the total reflection mirror reflects only the fluorescent X-rays in a desired wavelength band, so that the resolution is excellent. In the analysis of elements heavier than Mo or higher, the resolution is also excellent because a semiconductor detector is used. Further, since a total reflection mirror having a much higher reflection efficiency than that of the spectral element is used, the S / N ratio is high as an apparatus. Therefore, highly accurate and sensitive analysis can be performed with sufficient accuracy.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to a first embodiment of the present invention will be described below. First, regarding the configuration of this device,
This will be described with reference to FIG. This apparatus allows a sample table 2 on which a sample 1 is mounted, 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 to pass therethrough. And a solar slit 11. Further, a spectroscopic element exchanger 14 having, for example, two types of spectroscopic elements 6, which selectively advances to the optical path of the fluorescent X-rays 13 passing through the solar slit 11 and splits the incident fluorescent X-rays 13, And a semiconductor detector 8 for measuring the intensity of the fluorescent X-rays 7 that have been spectrally separated. Further, while changing the wavelength of the fluorescent X-rays 7 separated by the spectral element 6, the spectroscopic element exchanger 14 and the semiconductor detector 8 are linked so that the separated fluorescent X-rays 7 enter the semiconductor detector 8. There is provided an interlocking means 10 for causing the operation.

Here, the two types of spectral elements 6A and 6B are:
For example, Pentaerythritol (PET) and LiF.
As the semiconductor detector 8, a silicon detector (Si (L
i)), a solid-state device such as a germanium detector, a silicon drift detector (SDD), and a superconducting radiation detector (STJ) can be used. In particular, Pert regardless of liquid nitrogen
The one that performs cooling by an ier element is compact and suitable for implementing the present invention.

The interlocking means 10 is a so-called goniometer. When the fluorescent X-rays 13 enter the spectroscopic element 6A at a certain incident angle θ, the extension line 9 of the fluorescent X-rays 13 and the spectroscopic element 6A
The fluorescent X-rays 7 spectrally (diffracted) at 2 form a spectral angle 2θ twice the incident angle θ, but the interlocking means 10 changes the spectral angle 2θ to change the wavelength of the fluorescent X-rays 7 In order that the separated fluorescent X-rays 7 enter the semiconductor detector 8,
The spectroscopic element 6A is rotated via the spectroscopic element exchanger 14 about an axis O perpendicular to the paper surface passing through the center of the surface of the spectroscopic element 6A, and the semiconductor detector 8 is rotated by twice the rotation angle. It is rotated (scanned) along the circle 12 around O. In the interlocking means 10, the incident angle θ and the spectral angle 2θ formed as a result of rotation of the spectroscopic element 6A and the semiconductor detector 8 are confirmed by, for example, a potentiometer attached to the axis O.

The interlocking means 10 is connected to the spectral element exchanger 1
4 and the semiconductor detector 8 may be mechanically connected by a drive mechanism such as a gear mechanism, and the gear mechanism or the like may be driven by a single drive source such as a motor, or the spectral element exchanger 14 and the semiconductor detector 8 may be driven by independent drive sources and drive mechanisms, and the above-described operation may be realized by appropriately controlling the drive sources.

[0015] Further, as shown in FIG.
The semiconductor detector 8 includes a moving unit 15 for moving the intensity of the fluorescent X-rays 5 generated from the sample 1 to a position where the intensity is measured without passing through the solar slit 11 and the spectral element 6. In this movement, the solar slit 11 and the spectral element exchanger 14
If it is necessary to evacuate to avoid interference,
5 also evacuates them. The moving means 15 also includes a driving source such as a motor and a driving mechanism such as a gear mechanism, but may be independent of the interlocking means 10.
At least part of the interlocking means 10 may be common.

Next, the operation of this device will be described.
First, when analyzing an element as light as Al, for example, the spectroscopic element exchanger 14 of FIG. 1 is rotated about a central axis P perpendicular to the plane of the drawing, and an appropriate PET spectroscopic element 6A is analyzed.
Is selected to enter the optical path of the fluorescent X-ray 13 passing through the solar slit 11. When the primary X-ray 3 is irradiated from the X-ray source 4 to the sample 1 placed on the sample stage 2, the fluorescent X-rays 5 generated from the sample 1
1 and is separated by the spectroscopic element 6A, and the intensity of the separated fluorescent X-ray 7 is measured by the semiconductor detector 8. here,
By interlocking the spectroscopic element 6A and the semiconductor detector 8 with the interlocking means 10, the fluorescent X-rays 5 generated from the sample 1 are passed through the solar slit 11 and first optically split into the respective wavelengths by the spectroscopic element 6A. In addition, the semiconductor detector 8 having a higher energy resolution and a wave height analyzer (not shown) electrically separate and detect the electric power.

In the case of analyzing an element heavier than Fe, for example, the spectroscopic element exchanger 14 is rotated about a central axis P perpendicular to the plane of the drawing, and an appropriate LiF spectroscopic element 6B is It is selected so as to enter the optical path of the fluorescent X-ray 13 passing through the slit 11. Thereafter, the fluorescent X-rays 5 of each wavelength are separated and detected in the same manner as described above.

As described above, according to the apparatus of the first embodiment, first, only the semiconductor detector 8 is used as the detector, so that the configuration is simple. In addition, in the analysis of elements as light as Al and Fe while selecting the appropriate spectroscopic elements 6A and 6B while using the interlocking means 10 to cope with the fluorescent X-rays 5 in a wide wavelength range, the resolution is excellent, and about Mo. In the analysis of heavy elements as described above, the semiconductor detector 8 is used, so that the resolution is also excellent. Therefore, highly accurate and sufficiently accurate analysis can be performed. Among the elements heavier than Fe,
For analysis of elements heavier than Mo, only electrical energy decomposition by the semiconductor detector 8 and the pulse height analyzer is sufficient, and the spectroscopic element 6 is not required.

Subsequently, when analyzing a minute portion of the sample 1 (including a case where the whole sample 1 is minute), the fluorescent X-ray 5
The operation in the case where the intensity is weak is described. First, as shown in FIG.
Is moved to a position where the intensity of the fluorescent X-rays 5 generated from the sample 1 is measured without passing through the solar slit 11 and the spectroscopic element 6, and is brought close to the sample 1 placed on the sample stage 2. When the sample 1 is irradiated with the primary X-rays 3 from the X-ray source 4, the fluorescent X-rays 5 generated from the sample 1 are directly incident on the semiconductor detector 8 and have high energy resolution. And electrically separated by a wave height analyzer. Thus, according to the apparatus of the first embodiment, the moving means 15 causes the fluorescent X-rays 5 generated from the sample 1 to directly enter the semiconductor detector 8 without passing through the solar slit 11 or the spectroscopic element 6. Therefore, even when the intensity of the fluorescent X-rays 5 generated from the sample 1 is weak, the measurement can be performed at a high S / N ratio. Therefore, highly sensitive and sufficiently accurate analysis can be performed.

Next, an apparatus according to a second embodiment of the present invention will be described. First, the configuration of this device will be described with reference to FIG. The apparatus includes a sample table 2 on which a sample 1 is placed and an X-ray tube or the like for irradiating the sample 1 with primary X-rays 3.
The apparatus includes a radiation source 4 and a solar slit 11 through which fluorescent X-rays 5 generated from the sample 1 pass. Further, a total reflection mirror 16 that reflects a part of the fluorescent X-rays 13 passing through the solar slit 11 and a semiconductor detector 8 that measures the intensity of the fluorescent X-rays 17 reflected by the total reflection mirror 16 are provided. ing. Further, the wavelength band of the fluorescent X-rays 17 reflected by the total reflection mirror 16 is changed, and the reflected fluorescent X-rays 1 are changed.
7 so that the total reflection mirror 1 is incident on the semiconductor detector 8.
6 and a rotation means 18 for rotating the semiconductor detector 8. Here, the total reflection mirror 16 is made of, for example, soda-lime glass, and the same semiconductor detector 8 as that of the first embodiment can be used.

The total reflection mirror 16 totally reflects the fluorescent X-rays 17 of which the critical angle of total reflection is larger than φ among the fluorescent X-rays 13 incident at the oblique angle φ, and absorbs the other fluorescent X-rays. I do. In general, a fluorescent X-ray having a lower energy, that is, a longer wavelength, has a larger total reflection critical angle. Therefore, if the viewing angle φ is set slightly smaller than the critical angle of the desired fluorescent X-ray 17, the desired fluorescent X-ray can be obtained. By causing the total reflection mirror 16 to absorb fluorescent X-rays having higher energy than the line 17, that is, having a shorter wavelength, unnecessary excitation lines 3 and the like can be removed.

The rotating means 18 changes the wavelength band of the fluorescent X-rays 17 reflected by the total reflection mirror 16 and makes the reflected fluorescent X-rays 17 enter the semiconductor detector 8. Specifically, the total reflection mirror 16 is placed on a paper surface passing through the center of its surface so that the viewing angle φ is slightly smaller than the critical angle of the fluorescent X-ray of the element to be analyzed having the shortest wavelength. Around an axis Q perpendicular to
The semiconductor detector 8 is rotated along the circle 12 about the axis Q, and the fluorescence X reflected at the reflection angle φ of the same angle as the viewing angle φ
It is located in the optical path of line 17. In the rotating means 10, for example, the incident angle φ and the reflection angle φ formed by rotating the total reflection mirror 16 and the semiconductor detector 8 are confirmed by a potentiometer or the like attached to the axis Q.

The fluorescent X-rays 17 reflected by the total reflection mirror 16 set at such a viewing angle φ include all the fluorescent X-rays in a desired wavelength band.
It is not necessary to rotate and scan the semiconductor detector 8 while rotating the spectroscopic element 6 as in the interlocking means 10 (FIG. 1) of the first embodiment. Further, the rotating means 18 may be a means for mechanically connecting the total reflection mirror 16 and the semiconductor detector 8 by a driving mechanism such as a gear mechanism, and driving the gear mechanism or the like by a driving source such as a single motor. Then, the total reflection mirror 16 and the semiconductor detector 8 may be driven by independent drive sources and drive mechanisms, and the drive sources may be appropriately controlled to realize the above-described operation.

Next, the operation of this device will be described.
First, when analyzing an element as light as Al, for example, the rotation angle is set so that the viewing angle φ is slightly smaller than the critical angle of the fluorescent X-ray of the element to be analyzed having the shortest wavelength. By means 16, the total reflection mirror 16 is rotated, and the semiconductor detector 8 is rotated so as to be located in the optical path of the fluorescent X-ray 17 reflected at the reflection angle φ.
Then, the sample 1 placed on the sample stage 2
When the next X-ray 3 is irradiated, the fluorescent X-rays 5 generated from the sample 1 pass through the solar slit 11, are partially reflected by the total reflection mirror 16, and the intensity of the reflected fluorescent X-rays 17 is detected by a semiconductor. It is measured by the measuring device 8. Here, by setting the viewing angle φ as described above, only the fluorescent X-rays 17 of the heaviest or lighter element among the elements to be analyzed are reflected by the total reflection mirror 16, and the desired element Are electrically separated and detected by the semiconductor detector 8 having a high energy resolution and a wave height analyzer (not shown).

Also, for example, when analyzing an element heavy as much as Mo or more, similarly, the critical angle of the fluorescent X-ray of the element to be analyzed having the shortest wavelength is determined by the critical angle.
The viewing angle φ is set to be slightly smaller, and the fluorescent X-rays 17 of the heaviest or lighter element among the elements to be analyzed are reflected by the total reflection mirror 16,
Among them, fluorescent X-rays of a desired element are electrically separated and detected by the semiconductor detector 8 having high energy resolution and a wave height analyzer (not shown). In this case, the wavelength band of the fluorescent X-rays 17 reflected by the total reflection mirror 16 is widened and the effect of the spectral reflection by the total reflection mirror 16 is reduced. Only electrical energy decomposition by the detector 8 and the pulse height analyzer is sufficient.

The rotation of the total reflection mirror 16 for changing the wavelength band of the reflected fluorescent X-rays 17 is performed by changing the wavelength of the fluorescent X-rays 7 to be changed in the apparatus of the first embodiment. Compared to the rotation (FIG. 1), it is much smaller, so if the width of the entrance of the semiconductor detector 8 is sufficiently large, the reflected fluorescent X-rays 17 can be incident even if the semiconductor detector 8 is fixed. Can be. In such a case, the rotation means 18 need only rotate the total reflection mirror 16 and does not need to rotate the semiconductor detector 8.

As described above, according to the device of the second embodiment, first, only the semiconductor detector 8 is used as the detector, so that the configuration is simple. Moreover, while analyzing the X-rays 5 in a wide wavelength range by the rotating means 18 and analyzing the elements as light as Al and Fe, the total reflection mirror 16 reflects only the X-rays 17 in a desired wavelength band. Therefore, in the analysis of elements heavier than Mo or so, the semiconductor detector 8 is used, so that the resolution is also excellent. Further, the total reflection mirror 16 having a much higher reflection efficiency than the spectral element
Is used, the S / N ratio is also high for the device. Therefore, highly accurate and sensitive analysis can be performed with sufficient accuracy.

In the apparatus of the first and second embodiments, a parallel optical system in which the solar slit 11 and the flat spectral element 6 or the total reflection mirror 16 are combined is used. A concentrated optical system combining a slit and a curved spectral element or a total reflection mirror may be used. When a concentrated optical system is used and the so-called Rowland circle is not moved, the interlocking means and the rotating means need to interlock and rotate the slit.

[0029]

As described in detail above, according to the present invention, a highly accurate and highly sensitive analysis can be performed with high accuracy and sensitivity with a simple configuration using only a semiconductor detector as a detector. In addition, as in an apparatus using a gas flow type proportional counter, P
Since the methane gas in the R gas does not stick to the core wire of the counter tube and the resolution does not decrease, maintenance is easy and stable and accurate analysis can be performed for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a fluorescent X-ray analyzer according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing the same apparatus when analyzing a minute part of a sample.

FIG. 3 is a schematic diagram showing a fluorescent X-ray analyzer according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... sample, 2 ... sample stage, 3 ... primary X-ray, 4 ... X-ray source, 5
... X-ray fluorescence emitted from the sample, 6 ... Spectroscopy element, 7 ... X-ray fluorescence separated by the spectroscopy element, 8 ... Semiconductor detector, 10 ...
Interlocking means, 11: slit, 13: fluorescent X-rays passing through the slit, 14: spectral element exchanger, 15: moving means, 1
6: total reflection mirror; 17: fluorescent X-ray reflected by the total reflection mirror; 18: rotating means.

Claims (3)

[Claims] A sample stage 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; A spectroscopic element exchanger that selectively advances into the optical path of the fluorescent X-rays passing through the slit and disperses the incident fluorescent X-rays; and a semiconductor detector that measures the intensity of the fluorescent X-rays separated by the spectroscopic element. While changing the wavelength of the fluorescent X-rays split by the spectroscopic element, at least one of the slit, the spectral element exchanger, and the semiconductor detector so that the split fluorescent X-rays enter the semiconductor detector. An X-ray fluorescence analyzer comprising: an interlock for interlocking an element exchanger and a semiconductor detector. 2. The X-ray fluorescence analyzer according to claim 1, further comprising a moving unit that moves the semiconductor detector to a position where the intensity of the X-ray fluorescence generated from the sample is measured without passing through the slit and the spectral element. apparatus. 3. A sample stage 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 total reflection mirror that reflects a part of the light, a semiconductor detector that measures the intensity of the fluorescent X-ray reflected by the total reflection mirror, and a wavelength band of the fluorescent X-ray that is reflected by the total reflection mirror, An X-ray fluorescence analyzer, comprising: a rotating means for rotating at least the total reflection mirror of the slit, the total reflection mirror, and the semiconductor detector so that the reflected X-rays are incident on the semiconductor detector.