JP2004004125A - Fluorescent x-ray analysis apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply switch from ordinary arrangement of a monochrometer to Cartesian arrangement. <P>SOLUTION: One end of a monochrometer 20 for exciting a monochro radiation source having an X-ray tube 10 at the other end thereof is fitted to a fluorescent X-ray analysis apparatus body 2 at two fitting angles different from each other by 90 degrees taking the optical axis of the monochro X-ray as the center of rotation. Thus, two incident angles different from each other by 90 degrees of monochro X-rays from the monochrometer for exciting the monochro radiation source are made to a sample, whereby the monochro X-ray to the sample can be easily switched between the ordinary incident direction and the Cartesian arrangement turned in a 90-degree arc from the incident direction. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a fluorescent X-ray analyzer.

In X-ray fluorescence analysis, a sample is irradiated with X-rays for excitation, X-rays generated from the sample are taken out through a diaphragm in response to the X-rays, and the X-ray fluorescence has a wavelength component corresponding to each element by a spectroscope. The X-rays are separated into spectra and the separated X-rays are detected by an X-ray detector, whereby qualitative analysis and quantitative analysis are performed. In the excitation of the sample by X-ray irradiation, a direct excitation that excites the sample with primary X-rays from an X-ray tube, and a monochrome source that excites the sample with X-rays (monochrome X-rays) of a specific wavelength in the primary X-rays Excitation is known.

Conventionally, X-ray fluorescence analysis by direct excitation using primary X-rays and X-ray fluorescence analysis by excitation of a monochromatic source using monochromatic rays include an X-ray tube or a monochromator and an X-ray tube as an X-ray source. It is performed by each dedicated X-ray fluorescence analyzer, or, for the same X-ray fluorescence analyzer, two X-rays: an X-ray tube for direct excitation, and an X-ray tube and a monochromator for excitation of a monochromatic source. This is achieved by setting up a source and switching between two X-ray sources depending on whether direct excitation or monochrome source excitation is performed.

In any case, in the conventional X-ray fluorescence analyzer, each X-ray source is installed in a state fixed to the analyzer main body. The reason why the X-ray source is fixed to the analyzer main body is to satisfy the positional relationship between the sample and the X-rays and the optical conditions for each excitation mode. For example, in the case of direct excitation, it is necessary to make the distance between the X-ray tube and the sample as short as possible in order to increase the irradiation accuracy and detection sensitivity of the primary X-ray to the sample. , The X-ray tube, the monochromator for exciting the monochromatic ray source, and the optical conditions must be positioned so as to satisfy the optical conditions. By fixing each X-ray source to the main body of the analyzer, it becomes easy to stably satisfy the above conditions.

However, to perform X-ray fluorescence analysis in two different excitation modes of direct excitation and monochromatic source excitation in a conventional X-ray fluorescence analyzer, it is necessary to use a dedicated X-ray fluorescence analyzer individually or to use two X-ray analyzers. In each case where the X-ray source of the fluorescent X-ray analyzer equipped with the X-ray source is switched and used, two X-ray tubes are provided, one for direct excitation and the other for monochromatic source excitation. And the cost of the X-ray analyzer increases.

When an X-ray source for direct excitation and an X-ray source for excitation of a monochromatic X-ray source are provided side by side in one X-ray fluorescence analyzer, the two X-ray sources are set in close proximity to the sample. Since it is necessary, it is difficult to satisfy the best optical conditions when each X-ray source is installed alone. For example, the best positional relationship or the best case such as making the distance between the sample and the X-ray tube different. Since it is installed in a state deviated from the optical conditions, the analysis performance such as the X-ray irradiation conditions for the sample and the intensity of X-rays detected from the sample is lower than when the X-ray source is installed alone. There is a problem of doing.

Also, in monochromatic source excitation, a Cartesian arrangement is known in which the monochromator is rotated by 90 degrees from a normal angle so that the polarization direction of the monochromatic source is the same as the plane direction formed by the monochromator. I have. A conventional X-ray fluorescence analyzer requires a separate X-ray source even in such a Cartesian arrangement.

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to perform X-ray excitation on a sample under optimum conditions for each excitation mode in X-ray fluorescence analysis. More specifically, it is an object of the present invention to provide an X-ray monochromator capable of performing X-ray excitation on a sample under optimal conditions for each excitation mode. An object of the present invention is to provide a fluorescent X-ray analyzer that can be performed under conditions.
In particular, it is an object of the present invention to provide a fluorescent X-ray analyzer that can easily switch a monochromator to a Cartesian arrangement.

The X-ray fluorescence spectrometer according to the present invention is characterized in that the other end of the monochromator for excitation of a monochromatic source having an X-ray tube at one end is at least 90% with respect to the main body of the X-ray fluorescence spectrometer with the optical axis of the monochromatic X-ray as a rotation center. It can be mounted at two different mounting angles. With this configuration, it is possible to set two incident angles different from each other by 90 degrees with respect to the sample of the monochrome X-ray from the monochromator for excitation of the monochrome source. Switching to the Cartesian arrangement rotated by 90 degrees from the direction can be easily performed.

Further, the present invention has a configuration in which a monochromator for excitation of a monochromatic ray source is switchably provided between the X-ray tube and the main body of the fluorescent X-ray analyzer, and the X-ray tube is directly attached to the main body of the fluorescent X-ray analyzer. Excitation and excitation of a monochromatic source by mounting an X-ray tube with a monochromator for monochromatic excitation in the X-ray fluorescence analyzer main body can be performed under optimal excitation conditions.

In the monochromator for excitation of a monochromatic ray source of the present invention, the shape of one end is the same as the shape of the attachment of the X-ray tube to the main body of the X-ray fluorescence analyzer, and the shape of the other end is the fluorescent X-ray to the X-ray tube. It can have the same shape as the mounting shape of the analyzer main body. By making each end of the monochromator for monochromatic excitation, the monochromator for excitation of the monochromatic source can be detached between the X-ray tube and the main body of the X-ray fluorescence analyzer. Therefore, when performing monochromatic X-ray source excitation, a monochromator for monochromatic X-ray source excitation is provided between the X-ray tube and the main body of the X-ray fluorescence spectrometer to emit monochromatic X-rays. On the other hand, when direct excitation is performed, an X-ray tube is provided directly on the main body of the X-ray fluorescence spectrometer, and the sample is irradiated with primary X-rays from the X-ray tube.

Further, in the X-ray fluorescence spectrometer of the present invention, the above-mentioned one end has the same shape as the attachment shape of the X-ray tube to the X-ray fluorescence main unit, and the other end has the attachment shape of the X-ray fluorescence main unit to the X-ray tube. A monochromator for monochromatic source excitation having the same shape as that of the X-ray tube and the main body of the X-ray fluorescence analyzer can be detachably provided, and the monochromator for monochromatic source excitation is removed, By directly attaching the X-ray tube to the main body of the X-ray fluorescence spectrometer, primary X-rays from the X-ray tube are irradiated to the sample to directly excite the sample, and between the X-ray tube and the main body of the X-ray fluorescence analyzer. The monochromator for monochromatic source excitation is attached to the monochromator to excite the monochromatic source using monochromatic X-rays from the monochromator for monochromatic source excitation. According to the present invention, the X-ray excitation of the sample can be performed under optimum conditions in both the direct excitation mode and the monochromatic source excitation mode.

As described above, the monochromator for excitation of the monochromatic source used to switch the mounting angle used in the apparatus of the present invention has one end having the same shape as the mounting shape of the X-ray tube with respect to the main body of the X-ray fluorescence analyzer, and the other end having the X-ray. The present invention can be applied to a monochromator for excitation of a monochromatic source having the same shape as the mounting shape of the main body of the X-ray fluorescence spectrometer with respect to the tube, or to a monochromator for excitation of a monochromatic source having a fixed X-ray tube. it can.

According to the X-ray fluorescence spectrometer of the present invention, the arrangement of the monochromator for the monochromatic source can be easily changed between the normal arrangement and the Cartesian arrangement, and the X-ray excitation for the sample is optimized for each excitation mode. Can be done with

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram for explaining a fluorescent X-ray analyzer to which the present invention is applied.
The X-ray fluorescence analyzer 1 includes an X-ray fluorescence measurement unit in a vacuum chamber of the X-ray fluorescence analyzer main body 2. In the fluorescent X-ray measurement unit, primary X-rays from the X-ray tube 10 are irradiated on the sample S, and secondary X-rays including fluorescent X-rays generated from the sample S are parallelized through the diaphragm and the solar slit 4 in response to the primary X-rays. The fluorescent X-rays are taken out as a beam, and the fluorescent X-rays are separated into a spectrum having a wavelength component corresponding to each element by the spectral crystal 5, and the separated fluorescent X-rays are detected by a detector 7 through a solar slit 6.

The intensity signal of the spectrum detected by the detector 7 is sent to the data processing unit 4 through a measuring unit including a linear amplifier, a pulse height analyzer, a scaler, and the like, and is subjected to analysis processing such as qualitative analysis and quantitative analysis. Data processing for obtaining X-ray intensity distribution data, element intensity distribution data and element content distribution data. The X-ray fluorescence analyzer main body 2 includes a mounting portion 3 having an opening at a primary X-ray incident position, and is detachably attached to the mounting portion 3 with an X-ray tube 10 or a monochromator 20 for exciting a monochromatic source. Mounted.

The first embodiment of the present invention will be described. The first aspect is characterized in that an X-ray tube and a monochromator for excitation of a monochromatic ray source are exchangeably attached to the X-ray fluorescence analyzer main body 2. FIG. 2 is a schematic diagram for explaining an X-ray tube and a monochromator for exciting a monochromatic source according to the present invention. 2, an X-ray tube 10 or a monochromator 20 for exciting a monochromatic source is detachably attached to the X-ray fluorescence analyzer main body 2.
The X-ray tube 10 is an X-ray source that generates primary X-rays. At one end of the X-ray tube 10, an X-ray mounting flange 11 for mounting the X-ray tube 10 to the X-ray fluorescence analyzer main body 2 is formed. You. The shape and size of the X-ray mounting flange 11 are formed corresponding to the mounting portion 3 on the X-ray fluorescence analyzer main body 2 side, and are mounted in a sealed state via an O-ring 12 and the like.

On the other hand, the monochromator for monochromatic source excitation monochromator 20 converts the primary X-rays from the X-ray tube 10 into monochromatic X-rays (monochromatic X-rays) having a specific wavelength. 25, a monochromator solar slit 26 is provided in order with a predetermined angular relationship. A monochromator incident side flange 21 for attaching the X-ray tube 10 is formed at an end where primary X-rays of the monochromator 20 for monochromatic source excitation are incident. Here, since the monochromator incident side flange 21 is formed in the same shape as the mounting portion 3 on the X-ray fluorescence analyzer main body 2 side, the monochromator incident side flange 21 and the X-ray mounting flange 11 must be fitted. Thereby, it can be attached in a sealed state via the O-ring 12 and the like.

{Circle around (2)} At the other end of the monochromator for monochromatic excitation, a monochromator mounting flange 23 for attaching the monochromator for monochromatic excitation 20 to the X-ray fluorescence analyzer main body 2 is formed. Here, the monochromator mounting flange 23 is formed in the same shape as the X-ray tube mounting flange 11 of the X-ray tube 10 and has a shape corresponding to the mounting portion 3 on the X-ray fluorescence analyzer main body 2 side. With this shape, the monochromator mounting flange 23 and the mounting portion 3 on the X-ray fluorescence analyzer main body 2 side are fitted to each other, so that the mounting can be performed in a sealed state via the O-ring 22 and the like.

Therefore, one end (monochromator mounting flange 23) of the monochromator 20 for excitation of the monochromatic ray source has the same shape as the shape of the mounting portion (X-ray tube mounting flange 11) of the X-ray tube 10 to the X-ray fluorescence analyzer main body 2, By making the other end (the flange 21 for monochromator incidence) the same as the shape of the attachment portion 3 of the X-ray fluorescence analyzer main body 2 with respect to the X-ray tube 10, the monochromator 20 for exciting the X-ray tube 10 or the monochromatic source can be obtained. Can be switchably attached to the X-ray fluorescence analyzer main body 2. Further, the X-ray tube 10 can be switchably attached to the monochromator 20 for monochromatic excitation.

Next, the excited state of the direct excitation by the X-ray tube 10 and the excited state of the monochromatic source excitation by the monochromator for monochromatic source excitation 20 to which the X-ray tube 10 is attached will be described with reference to FIGS.
In FIG. 3A, direct excitation by the X-ray tube 10 is performed by fitting the X-ray tube mounting flange 11 of the X-ray tube 10 to the mounting portion 3 of the X-ray fluorescence analyzer main body 2. The sample X placed in the X-ray fluorescence analyzer main body 2 is irradiated with the primary X-rays 30. As the X-ray tube 10, for example, an Rh window end window type can be used. The sample S is excited by the irradiation of the primary X-ray 30, and from the sample S, the fluorescent X-rays 33 and 34 and the scattered rays of the primary X-rays (the scattered rays 32 of the Rh characteristic X-rays and the continuous X-rays 35) are emitted. A secondary X-ray 31 is generated. This secondary X-ray 31 is converted into an electric signal corresponding to each wavelength by a spectroscope provided with a solar slit 4, a spectral crystal 5, a solar slit 6, and a detector 7 provided in the X-ray fluorescence analyzer 1. FIG. 4A schematically shows a spectrum in the case of the direct excitation.

In FIG. 3B, when the monochrome source is excited by the monochrome source excitation monochromator 20, the X-ray tube mounting flange of the X-ray tube 10 is attached to the monochromator incidence flange 21 of the monochrome source excitation monochromator 20. The X-ray tube 10 is mounted by fitting the X-ray tube 11, and the monochromator mounting flange 23 of the monochromator 20 for monochromatic excitation is fitted to the mounting portion 3 of the X-ray fluorescence analyzer main body 2. A parallel beam component is extracted by the solar slit 24 from the parallel X-ray, and is incident on the dispersive crystal 25 (eg, LiF) at an angle (θ = 8.78 °) at which a certain wavelength (eg, RhKα) is diffracted. . The monochromatic X-ray is diffracted from the spectral crystal 25 into a single wavelength RhKα, and the sample S is irradiated through the solar slit 26. From the sample S, secondary X-rays 41 including fluorescent X-rays 43 and scattered rays 42 of RhKα are generated. The secondary X-rays 41 correspond to respective wavelengths by a spectroscope including a solar slit 4, a spectral crystal 5, a solar slit 6, and a detector 7 provided in the X-ray fluorescence analyzer 1, as in the case of direct excitation. Converted to electrical signals.

FIG. 4 (b) schematically shows a spectrum in the case of excitation by the monochromatic source. Comparing the spectra of FIGS. 4A and 4B, the background of the fluorescent X-rays 43 excited by the monochromatic radiation source is significantly lower than the background of the fluorescent X-rays 33 excited by the direct excitation. As a result, the detection limit can be reduced according to the monochrome source excitation. Also, the fluorescent X-rays 34 by direct excitation in FIG. 4A are not detected because they are not excited by the monochromatic source excitation in FIG. 4B.

Next, a second embodiment according to the present invention will be described. The second aspect is characterized in that the mounting angle at which the monochromator for excitation of the monochromatic ray source is attached to the X-ray fluorescence analyzer main body 2 can be adjusted or changed. Adjust or change. In particular, it is suitable for switching between a normal arrangement in which monochrome X-rays enter the sample in a normal incident direction and a Cartesian arrangement rotated by 90 degrees from the normal incident direction.

Positioning portions that determine the mutual fitting positions are provided on the mounting portion 3 side of the fluorescent X-ray analyzer main body 2 and on the monochromator mounting flange 23 side of the monochromator 20 for excitation of a monochromatic source fitted to the mounting portion 3. Provide. The fitting position is formed in accordance with, for example, a normal arrangement in which monochrome X-rays are incident on the sample in a normal incident direction and a Cartesian arrangement rotated by 90 degrees from the normal incident direction.

FIGS. 5A and 5B show a state in which the monochromator 20 for exciting the monochromatic source is attached to the X-ray fluorescence analyzer main body 2 at two different mounting angles. FIG. 5A shows a normal arrangement in which monochrome X-rays are incident on a sample in a normal incident direction, and FIG. 5B shows a Cartesian arrangement rotated by 90 degrees from the normal incident direction. I have. According to the Cartesian arrangement, the incident direction is the same as the plane formed by the solar slit of the monochromator and the spectral crystal, and monochromatic X-rays that do not include 90-degree polarized light can be emitted.
Further, the mounting angle of the monochromator 20 for exciting the monochromatic ray source with respect to the X-ray fluorescence analyzer main body 2 is not limited to 90 degrees as described above, and may be any angle. By setting the attachment angle to an arbitrary angle, the incidence state of the monochrome X-rays on the sample S can be adjusted.

Note that the positioning portion may have any configuration such as a combination shape of a concave portion and a convex portion fitted to each other.
In the above-described example, a parallel beam system using a solar slit and a parallel crystal is adopted as the monochromator, but a focusing method using a curved crystal may be adopted. As the spectroscope used after the excitation, a wavelength-dispersion scanning spectrometer or a wavelength-dispersion fixed spectrometer may be used, or an energy-dispersion detector may be used.

According to the embodiment of the present invention, the switching between the direct excitation and the monochromatic source excitation can be performed by exchanging the X-ray tube and the monochromator for monochromatic source excitation with the fluorescent X-ray analyzer. In addition to maintaining the analysis accuracy of the apparatus, the cost of the apparatus can be reduced by using a common X-ray tube.

It is a schematic diagram for explaining a fluorescent X-ray analyzer to which the present invention is applied. FIG. 1 is a schematic diagram for explaining an X-ray tube and a monochromator for exciting a monochromatic ray source according to the present invention. FIG. 5 is a diagram illustrating an attached state of an X-ray tube and a monochromator for excitation of a monochromatic ray source to which the X-ray tube is attached to a main body of the X-ray fluorescence analyzer. FIG. 3 is a diagram showing a spectrum obtained by direct excitation and a spectrum obtained by monochrome source excitation. FIG. 3 is a diagram illustrating a state in which a monochromator for exciting a monochromatic ray source is attached to a main body of the X-ray fluorescence analyzer.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... X-ray fluorescence analyzer, 2 ... X-ray fluorescence analyzer main body, 3 ... Mounting part, 4, 6 ... Solar slit, 5 ... Spectral crystal, 7 ... Detector, 10 ... X-ray tube, 11 ... X-ray tube Mounting flange, 12, 22 O-ring, 20 monochromator for monochromatic source excitation, 21 monochromator incidence flange, 23 monochromator mounting flange, 24, 26 monochromator solar slit, 25 monochromator Dispersion crystal, 30 ... primary X-ray, 31 ... secondary X-ray, 32 ... scattering of characteristic X-ray of Rh, 33, 34 ... fluorescence X-ray, 35 ... scattering of continuous X-ray, 40 ... monochrome X-ray, 41: secondary X-ray, 42: scattered ray of RhKα, 43: fluorescent X-ray, S: sample.

Claims (1)

The other end of the monochromator for excitation of a monochromatic source having an X-ray tube at one end can be attached to the main body of the X-ray fluorescence analyzer at two different mounting angles different from each other by at least 90 degrees around the optical axis of the monochromatic X-ray. X-ray fluorescence analyzer.

Images