JP7328135B2 - X-ray analysis device, analysis method, and program - Google Patents

Description

TECHNICAL FIELD The present invention relates to an X-ray analysis apparatus for analyzing particulate matter using secondary X-rays generated from the particulate matter, an analysis method, and a program for causing a computer system to execute the analysis method.

It is known that when a substance is irradiated with X-rays, X-rays peculiar to that substance (called secondary X-rays) are generated. The main secondary X-rays generated by irradiating a substance with X-rays are fluorescent X-rays derived from the elements contained in the substance, and scattered X-rays generated when the incident X-rays are scattered by the substance. be.

Further, it is known to detect the secondary X-rays generated from the above substances and analyze the elements contained in the substances using the fluorescent X-rays among the detected secondary X-rays (for example, See Patent Document 1).

Patent No. 6096419

In recent years, there has been an increasing demand for techniques for analyzing elements contained in particulate matter present in gases such as exhaust gas. As a technique for analyzing elements contained in particulate matter, the above-described method using fluorescent X-rays is conceivable. This is because the elemental analysis method using fluorescent X-rays can accurately measure the elements contained in the substance at a level of the order of several ppm.

On the other hand, the intensity of fluorescent X-rays generated from particulate matter is determined not only by the amount of elements contained in the particulate matter, but also by the amount of particulate matter present in the measurement area and the amount of particulate matter in the measurement area. It also depends on the state. Therefore, in order to accurately measure the content of elements contained in particulate matter using fluorescent X-rays, it is necessary to determine whether the amount of particulate matter present in the measurement area is appropriate and whether the amount of particulate matter It is necessary to grasp the state in which is present in the measurement area.

SUMMARY OF THE INVENTION An object of the present invention is to grasp the state of particulate matter in a measurement region by a simple method in the analysis of particulate matter using secondary X-rays.

A plurality of aspects will be described below as means for solving the problem. These aspects can be arbitrarily combined as needed.
An X-ray analysis apparatus according to the present invention is an apparatus that analyzes particulate matter using fluorescent X-rays generated from particulate matter. An X-ray analysis apparatus includes a sample stage, an X-ray source, a detector, and a computing section.
Particulate matter is placed on the sample stage. The X-ray source irradiates the particulate matter placed on the sample stage with X-rays. The detector detects secondary X-rays generated by irradiating the particulate matter with X-rays. The computing unit acquires state information about the state of the particulate matter on the sample stage based on the intensity of the secondary X-rays detected by the detector. Further, the calculation unit analyzes elements contained in the particulate matter based on secondary X-rays generated from the particulate matter.
As a result, the X-ray analyzer according to the present invention can easily grasp the state (state information) of the particulate matter on the sample table using the secondary X-rays generated from the particulate matter. Also, using this state information, it is possible to determine whether or not the particulate matter, which is the sample to be measured, is suitable for performing fluorescent X-ray analysis.

The computing unit obtains information about the surface state of the particulate matter placed on the sample stage based on the intensity of the low-energy secondary X-rays having energy equal to or lower than the first energy among the secondary X-rays. good too.
Accordingly, the surface state of the particulate matter placed on the sample stage can be grasped using the property that secondary X-rays having low energy are generated on the surface of the matter.

The computing unit may obtain information about the surface area of the particulate matter placed on the sample stage based on the intensity of the low-energy secondary X-rays.
By using the property that secondary X-rays having low energy are generated on the surface of the substance, the surface area of the particulate matter placed on the sample stage can be grasped.

The computing unit may acquire information about the particle size of the particulate matter placed on the sample stage based on the intensity of the low-energy secondary X-rays.
Accordingly, the particle size of the particulate matter can be grasped using the property that secondary X-rays having low energy are generated on the surface of the matter.

The computing unit acquires information about the thickness of the particulate matter placed on the sample stage based on the intensity of the high-energy secondary X-rays having energy higher than the first energy among the secondary X-rays. good.
By using the characteristic that secondary X-rays having high energy are also generated from the inside of the substance, the thickness of the particulate matter placed on the sample stage can be grasped.

The computing unit may acquire the state information based on the intensity of the scattered X-rays generated from the particulate matter among the secondary X-rays.
Accordingly, the state of the particulate matter placed on the sample stage can be grasped regardless of the elements contained in the particulate matter.

The computing unit may acquire the state information based on the intensity of the fluorescent X-rays derived from the elements contained in the particulate matter among the secondary X-rays.
As a result, the state of the particulate matter placed on the sample stage can be grasped more accurately.

The above X-ray analysis apparatus may further include a calibration sample, an opening member, and a switching section. A calibration sample is used to calibrate X-rays detected by the detector. The aperture member is provided with an aperture through which the X-rays generated from the X-ray source pass. The switching unit switches and arranges the calibration sample or the aperture of the aperture member between the X-ray source and the sample stage.
Calibration of the X-ray analyzer and analysis of particulate matter placed on the sample stage are performed by switching which of the calibration sample and the aperture member is arranged between the X-ray source and the sample stage by the switching unit. can be easily switched between.

At least the surface of the sample stage on which the particulate matter is placed may have electrical conductivity.
Thereby, when removing the particulate matter from the sample table, it is possible to suppress the particulate matter from remaining on the sample table due to static electricity.

The surface of the sample stage may be coated with a conductive material. As a result, the surface of the sample table, which does not have conductivity, can be made conductive.

The material coated on the surface of the sample stage may be a conductive metal or diamond-like carbon. As a result, the surface of the sample table can be easily made conductive by the coating.

The sample stage may be made of conductive metal or graphite. As a result, the entire sample stage can be made conductive.

An analysis method according to another aspect of the present invention is a method for analyzing particulate matter using an X-ray analysis device provided with a sample stage. The analytical method includes the following steps.
A step of irradiating the particulate matter placed on the sample stage with X-rays.
A step of detecting secondary X-rays generated by irradiating the particulate matter with X-rays.
A step of obtaining state information about the state of the particulate matter on the sample stage based on the intensity of the detected secondary X-rays.
A step of analyzing elements contained in the particulate matter based on secondary X-rays generated from the particulate matter.
Thereby, the state information of the particulate matter on the sample stage can be easily grasped using the secondary X-rays generated from the particulate matter. Also, using this state information, it is possible to determine whether or not the particulate matter, which is the sample to be measured, is suitable for performing fluorescent X-ray analysis.

A program according to still another aspect of the present invention is a program that causes a computer to execute the following steps.
A step of irradiating the particulate matter placed on the sample stage with X-rays.
A step of detecting secondary X-rays generated by irradiating the particulate matter with X-rays.
A step of obtaining state information about the state of the particulate matter on the sample stage based on the intensity of the detected secondary X-rays.
A step of analyzing elements contained in the particulate matter based on secondary X-rays generated from the particulate matter.
Thereby, the state information of the particulate matter on the sample stage can be easily grasped using the secondary X-rays generated from the particulate matter. Also, using this state information, it is possible to determine whether or not the particulate matter, which is the sample to be measured, is suitable for performing fluorescent X-ray analysis.

Using the properties of secondary X-rays generated from particulate matter, the state of particulate matter on the sample stage can be grasped by a simple method.

The figure which shows the structure of an X-ray-analysis apparatus. The figure which shows the structure of an opening member. FIG. 4 is a diagram showing paths of X-rays when an aperture is arranged between the X-ray source and the sample stage; FIG. 4 is a diagram showing paths of X-rays when a calibration sample is placed between an X-ray source and a sample stage; 4 is a flow chart showing the operation of the X-ray analysis device; FIG. 3 is a diagram showing an example of a spectrum of secondary X-rays; FIG. 4 is a diagram showing an example of a case in which the intensity of high-energy secondary X-rays changes; FIG. 4 is a diagram schematically showing the relationship between the intensity of high-energy secondary X-rays and the thickness of particulate matter; FIG. 4 is a diagram showing an example of changing the intensity of low-energy secondary X-rays; FIG. 4 is a diagram schematically showing the relationship between the intensity of low-energy secondary X-rays and the state of particulate matter in the vicinity of the sample table; FIG. 4 is a diagram schematically showing the relationship between the particle diameter of particulate matter and the filling rate; FIG. 4 is a diagram showing the relationship between the particle size of particulate matter and the intensity of low-energy secondary X-rays;

1. First Embodiment (1) X-ray Analysis Apparatus An X-ray analysis apparatus 100 according to the first embodiment will be described below. The X-ray analyzer 100 detects fluorescent X-rays generated by irradiating the particulate matter P with X-rays, and performs fluorescent X-ray spectrum measurement or fluorescent X-ray analysis for analyzing elements contained in a sample. device. In the following, the terms "elemental analysis" and "analysis" are used to include "qualitative" and "quantitative" of elements.
The X-ray analysis apparatus 100 is arranged, for example, at or near the generation source of the particulate matter P to be measured, and identifies the element contained in the particulate matter P generated at the source and determines the content of the element on the spot. It can be measured by observation (in-line measurement).
The X-ray analysis device 100 that performs in-line measurement is arranged, for example, in the flue of exhaust gas discharged from incinerators and various factories, and particulate matter P (for example, particles containing heavy metals, etc.) contained in the exhaust gas. can be analyzed.

The X-ray analyzer 100 analyzes general particulate matter P such as, for example, cosmetic powder, food powder such as wheat, cornstarch and potato starch, and crystal powder such as salt, in addition to particulate matter contained in the exhaust gas. is also possible.

A specific configuration of the above-described X-ray analysis apparatus 100 will be described below with reference to FIG. FIG. 1 is a diagram showing the configuration of an X-ray analysis apparatus. The X-ray analysis apparatus 100 mainly includes a sample support section 1 , an X-ray source 2 , a detector 3 , an aperture member 4 , a shield 5 and a calculation section 6 .

(2) Sample Supporting Section The sample supporting section 1 has a horizontal plate shape, and supports the particulate matter P to be measured by placing the particulate matter P thereon. The sample support section 1 has a base section 13 and a detachable section 12 that is detachable from the base section 13 . The base portion 13 and the attachment/detachment portion 12 are both formed with a through hole 11 and have a substantially flat plate shape. An X-ray transparent film 14 is stretched so as to block the through hole 11 , and the X-ray transparent film 14 is sandwiched and fixed between the base portion 13 and the detachable portion 12 . With the detachable portion 12 removed, the X-ray permeable film 14 is stretched over the through hole 11 of the base portion 13, and the detachable portion 12 is attached to the base portion 13, whereby the X-ray permeable film 14 is fixed.

A sample stage 15 is provided on the side of the through-hole 11 opposite to the side on which the X-ray permeable film 14 is stretched. Particulate matter P to be measured is placed on a sample stage 15 . The sample stage 15 prevents particulate matter P from entering the optical system (X-ray source 2, detector 3, etc.) of the X-ray analysis apparatus 100. FIG.
The sample table 15 is, for example, a plate-shaped member made of resin or plastic containing carbon elements, such as acrylic resin or polycarbonate. At least the surface (upper surface) of the sample table 15 on which the particulate matter P is placed is coated with a conductive material. In addition, the conductive material may be coated on the entire sample table 15 .

The conductive coating on the sample table 15 can be realized by coating the surface of the sample table 15 with a conductive metal such as gold, for example, by vapor deposition. Moreover, in order to prevent the conductive coating from peeling off from the sample stage 15, the surface of the sample stage 15 may be coated with another metal or the like before the conductive coating.
In addition, it is preferable that the material used for the conductive coating does not generate fluorescent X-rays having the same energy as or close to that of the fluorescent X-rays from the element to be measured when irradiated with X-rays.

In another embodiment, the conductive metal coating can be realized by applying a paste-like liquid containing a high concentration of metal powder such as nickel paste to the sample table 15 and drying it. can also

In yet another embodiment, for example, the surface of the sample stage 15 can be coated with diamond-like carbon. Since the diamond-like carbon coating film has high flatness, the particulate matter P can be easily removed from the sample stage 15 .

When the sample table 15 made of a transparent material such as acrylic resin or polycarbonate is coated, the coating film may be made thin so that the sample table 15 can transmit light.
As a result, the state of the particulate matter P placed on the sample stage 15 can be photographed by the imaging device 9, which will be described later. In addition, the conductive coating film can be made thin because it is sufficient if the conductive coating is sufficiently conductive to allow the charge to escape from the sample table 15 .

Alternatively, by coating the sample table 15 with a conductive transparent film, charging of the sample table 15 can be prevented and the particulate matter P can be photographed by the imaging device 9 .

In yet another embodiment, the sample stage 15 itself may be made of a conductive metal such as graphite or gold. Thereby, the entire sample table 15 can be made conductive.

In this embodiment, the sample stage 15 is connected to ground potential. Thereby, when the particulate matter P is removed from the sample table 15, it is possible to suppress the particulate matter P from remaining on the sample table 15 due to static electricity.
In another embodiment, the sample stage 15 may be connected to a voltage generator for applying a predetermined potential. The voltage generator applies a potential having the same polarity as the potential (positive potential, negative potential) of the particulate matter P to the sample stage 15 . As a result, a repulsive force acts between the sample table 15 and the particulate matter P, and it is possible to suppress the particulate matter P from remaining on the sample table 15 due to static electricity.

(3) X-Ray Source The X-ray source 2 is arranged at a position that irradiates the lower surface of the particulate matter P placed on the sample table 15 with X-rays obliquely from below. The X-ray source 2 is configured using an X-ray tube, and is arranged so that the X-ray emitting end is directed toward the through hole 11 of the sample support 1 .
As will be described later, in this embodiment, scattered X-rays are used to acquire information (state information) about the state of the particulate matter P placed on the sample stage 15 . Therefore, in order to generate scattered X-rays from the particulate matter P, the X-rays output from the X-ray source 2 preferably have energy of 10 keV or less. As such an X-ray source 2, for example, an X-ray source with a palladium target or an X-ray source with a rhodium target can be used.

(4) Detector The detector 3 is arranged at a position where it can detect secondary X-rays emitted obliquely downward from the lower surface of the particulate matter P placed on the sample stage 15 . The detector 3 is configured using, for example, an X-ray detection element such as a Si element (for example, a silicon drift detector (SDD)). placed towards.

By arranging the X-ray source 2 and the detector 3 as described above, X-rays are irradiated from the X-ray source 2 to the particulate matter P on the sample table 15, and the particulate matter P generates secondary X-rays. do. This secondary X-ray is detected by the detector 3 . In FIG. 1, X-rays emitted from the X-ray source 2 toward the sample table 15 and secondary X-rays incident on the detector 3 from the sample table 15 are indicated by broken lines.

(5) Aperture Member The aperture member 4 is arranged directly below the sample support section 1 and on the X-ray path from the X-ray source 2 to the sample support section 1 . The aperture member 4 is a member having an aperture through which the X-rays output from the X-ray source 2 pass. A specific configuration of the opening member 4 will be described below with reference to FIG. FIG. 2 is a diagram showing the configuration of the opening member.
The aperture member 4 is, for example, a plate-shaped member made of tantalum, and is formed with a plurality of apertures 41, 42, and 43 having different diameters through which X-rays pass. Note that the number of openings is not limited to three, and may be two or four or more. The plurality of openings 41, 42, 43 are arranged in a horizontal plane along a direction intersecting the direction in which the X-ray source 2 and the detector 3 are arranged.

A window portion 45 is provided in the opening member 4 . The window part 45 is configured using a transparent member such as an acrylic plate, for example. The window part 45 is provided at a position along the direction in which the openings 41, 42, 43 are arranged.

Furthermore, the aperture member 4 is provided with a calibration sample 44 . The calibration sample 44 is a sample for calibrating X-rays detected by the detector 3 . The calibration sample 44 is provided, for example, on the opposite side of the window portion 45 along the direction in which the openings 41, 42, and 43 are arranged.

Here, calibration performed in the X-ray analysis apparatus 100 will be described.
Calibration performed in the X-ray analysis device 100 using secondary X-rays includes energy calibration for calibrating the device so that the peak position of the fluorescent X-rays generated from the particulate matter P is at the correct energy position, and X-ray and intensity calibration for calibrating the intensity of

Among the above, energy calibration can be performed using fluorescent X-rays generated from the particulate matter P placed on the sample stage 15 if the elements contained in the particulate matter P to be measured are known.
On the other hand, intensity calibration cannot be performed using secondary X-rays generated from the particulate matter P placed on the sample stage 15 . This is because the intensity of secondary X-rays detected by the detector 3 varies depending on the particulate matter P placed on the sample table 15 .

Therefore, in this embodiment, the calibration sample 44 provided in the opening member 4 is a sample for intensity calibration. As a strength calibration sample, for example, a copper (Cu) plate member can be used.

In addition, when the element contained in the particulate matter P to be measured is unknown, a sample for energy correction may be provided as the calibration sample 44 . As a sample for energy correction, for example, a substance containing a predetermined amount of a predetermined element, such as a standard substance defined by NIST (National Institute of Standards & Technology), can be used.

As shown in FIG. 2 , the opening member 4 is connected to the switching section 7 via a shaft 71 . The switching unit 7 switches and arranges one of the openings 41 , 42 , 43 of the opening member 4 , the calibration sample 44 , or the window 45 between the X-ray source 2 and the sample stage 15 . The switching unit 7 can be configured by, for example, a known mechanism for moving a shaft 71 having one longitudinal end connected to the opening member 4 in its longitudinal direction.

3A and 3B, X-ray paths when the openings 41, 42, 43 or the calibration sample 44 are alternately arranged between the X-ray source 2 and the sample stage 15 will be described. . FIG. 3A is a diagram showing paths of X-rays when an aperture is placed between the X-ray source and the sample table. FIG. 3B is a diagram showing paths of X-rays when a calibration sample is placed between the X-ray source and the sample table.
When any one of the openings 41, 42, 43 is arranged between the X-ray source 2 and the sample table 15, the X-rays generated from the X-ray source 2 pass through the X-ray source 2 and the sample stage 15 as shown in FIG. It passes through one of the openings 41 , 42 , 43 arranged between the sample stages 15 . As a result, the X-rays output from the X-ray source 2 are adjusted in beam diameter (intensity) according to the diameters of the openings 41, 42, and 43, and reach the particulate matter P placed on the sample stage 15. do.

On the other hand, when the calibration sample 44 is arranged between the X-ray source 2 and the sample stage 15, the X-rays generated from the X-ray source 2 are scattered in the calibration sample 44 as shown in FIG. 3B. and passes through the opening 51 provided in the shield 5 . X-rays passing through the opening are detected by the detector 3 .

Further, when the window portion 45 is arranged between the X-ray source 2 and the sample table 15, the imaging element 9 (for example, CCD image sensor, CMOS image sensor, etc.) arranged directly below the through-hole 11 ( 1), the particulate matter P placed on the sample table 15 can be photographed.

By switching between the calibration sample 44 or the apertures 41, 42, and 43 of the aperture member 4 to be arranged between the X-ray source 2 and the sample stage 15 by the switching unit 7, the calibration of the X-ray analysis apparatus 100 can be performed. and the analysis of the particulate matter P placed on the sample table 15 can be easily and automatically switched and executed.

(6) Shield The shield 5 is a member made of, for example, aluminum and/or copper. A shield 5 is arranged at a position intermediate the X-ray source 2 and the detector 3 .
Also, the shield 5 is coupled to the opening member 4 . Accordingly, the shield 5 is adapted to move together with the opening member 4 . Further, an aperture 51 (FIG. 3B) is provided in the portion of the shield 5 corresponding to the position of the aperture member 4 where the calibration sample 44 is provided.

By arranging the shield 5 at the position described above and providing the opening 51 in the shield 5, when the particulate matter P is analyzed, the exit 21 of the X-ray source 2 and the entrance of the detector 3 X-rays passing through the path connecting the X-ray source 2 and the detector 3 are prevented from entering directly from the X-ray source 2 .
On the other hand, during calibration of the X-ray analysis apparatus 100, the X-rays output from the exit port 21 of the X-ray source 2 are scattered by the calibration sample 44, pass through the opening 51, and reach the detector 3. do.

(7) Operation Unit The operation unit 6 is a computer system having a CPU (Central Processing Unit), a storage device such as a RAM, a ROM, a hard disk, and an SSD (Soil State Disk), a display unit, various interfaces, and the like. be.
A part or all of each function of the calculation unit 6 described below may be implemented by a program stored in the storage device of the computer system. Moreover, some or all of the functions of the constituent elements of the calculation unit 6 may be realized by a semiconductor device such as a custom IC.

The calculation unit 6 implements a function of controlling each component (the X-ray source 2, the detector 3, the switching unit 7) of the X-ray analysis apparatus 100. FIG. Further, based on the intensity of secondary X-rays (scattered X-rays, fluorescent X-rays) detected by the detector 3, information on the state of the particulate matter P on the sample stage 15 (hereinafter referred to as state information) is obtained. Realize the function to get.

Furthermore, the calculation unit 6 executes signal processing for analysis of the particulate matter P. FIG. Specifically, the calculation unit 6 acquires the relationship between the energy of the X-rays detected by the detector 3, that is, the secondary X-rays generated from the particulate matter P and the count number, that is, the spectrum of the secondary X-rays. process.

The calculation unit 6 further realizes a function of performing qualitative analysis or quantitative analysis of elements contained in the particulate matter P using fluorescent X-rays contained in the secondary X-rays. Specifically, the element contained in the particulate matter P can be specified from the peak position of the fluorescent X-ray, and the content of the element can be calculated from the peak intensity of the fluorescent X-ray.

As shown in FIG. 1 , a display unit 8 is connected to the computing unit 6 . The display unit 8 is, for example, a display such as a liquid crystal display or an organic EL display.
At the time of analysis, the calculation unit 6, for example, the spectrum of the secondary X-ray detected by the detector 3, the content of the element to be measured contained in the particulate matter P (change in content over time, current content ) and the like are displayed on the display unit 8 .
In addition, the calculation unit 6 displays, for example, a list of the types of particulate matter P to be measured, elements to be measured, and the like on the display unit 8 .

Furthermore, the X-ray analysis apparatus 100 may include a device for measuring the state of the particulate matter P placed on the sample stage 15 . For example, a device for measuring the deposition thickness of the particulate matter P by irradiating the particulate matter P with an ultrasonic wave, a laser, or the like may be provided.
In this case, the calculation unit 6 may calculate the volume thickness and the like of the particulate matter P based on the intensity and the like of the ultrasonic wave and/or the laser.

(8) Operation of the X-ray analysis device (8-1) Overall operation Hereinafter, the overall operation until the particulate matter P is analyzed by the secondary X-rays detected by the detector 3 will be described using FIG. do. FIG. 4 is a flow chart showing the overall operation of the X-ray analysis apparatus.
When the X-ray analysis apparatus 100 starts operating, first, the calculation unit 6 commands the X-ray source 2 to output X-rays in step S1. As a result, the particulate matter P placed on the sample stage 15 is irradiated with the X-rays output from the X-ray source 2 .

While the particulate matter P is being irradiated with X-rays, the spectrum of secondary X-rays generated from the particulate matter P is acquired in step S2. Specifically, first, the detector 3 outputs the count number of detected secondary X-rays to the calculation unit 6 . After that, the calculation unit 6 acquires the spectrum of the secondary X-rays from the input count number of the secondary X-rays.

After acquiring the spectrum of the secondary X-rays, in step S3, the computing unit 6 acquires state information based on the intensity of the secondary X-rays acquired in step S2. The state information acquisition process in step S3 will be described later in detail.

After acquiring the state information, the computing unit 6 determines the state of the particulate matter P on the sample table 15 based on the state information in step S4, and determines whether or not to perform the elemental analysis of the particulate matter P. decide.
Based on the state information, for example, if it is determined that a sufficient amount of particulate matter P is placed on the sample table 15 and part of the particulate matter P is not floating from the sample table 15 ( "Yes" in step S4) That is, when it is determined that the state of the particulate matter P is suitable for elemental analysis, the computing unit 6 performs elemental analysis of the particulate matter P in step S5.

In step S5, the calculation unit 6 may perform elemental analysis using the secondary X-ray spectrum acquired in step S2, or newly acquire a secondary X-ray spectrum in step S5. However, elemental analysis may be performed.

On the other hand, based on the state information, for example, it may be determined that a sufficient amount of particulate matter P is not placed on the sample table 15, or part of the particulate matter P is floating from the sample table 15. If it is determined ("No" in step S4), that is, if it is determined that the state of the particulate matter P is unsuitable for elemental analysis, the computing unit 6 determines in step S6 that the state of the particulate matter P is an elemental Perform processing as appropriate for the analysis. For example, more particulate matter P is placed on the sample table 15 or the sample table 15 is vibrated to fill the gap between the particulate matter P and the sample table 15 .
After that, the calculation unit 6 executes the above steps S1 to S4 in order to confirm whether or not the state of the particulate matter P has become suitable for elemental analysis as a result of execution of step S6.
In another embodiment, the calculation unit 6 may decide not to analyze the particulate matter P in step S6.

(8-2) Acquisition of state information (8-2-1) State information obtained from secondary X-rays (outline)
Acquisition of status information executed in step S3 will be described below. First, state information obtained from the secondary X-ray spectrum will be described in detail. In the following description, it is assumed that the secondary X-ray spectrum as shown in FIG. 5 was acquired during a certain measurement. FIG. 5 is a diagram showing an example of a secondary X-ray spectrum.
In FIG. 5, the solid line represents the spectrum of the secondary X-rays generated from the particulate matter P, and the X-rays detected when the particulate matter P is not placed (that is, the X-rays output from the X-ray source 2). The spectrum of X-rays (X-rays) is represented by a dotted line.

In FIG. 5, peaks appearing with energy values E1, E2, and E3 are assumed to be peaks derived from the target of the X-ray source 2. In FIG. On the other hand, it is assumed that the peaks appearing at the energy values E4 and E5 are peaks due to fluorescent X-rays of elements contained in the particulate matter P (the peaks may be fluorescent X-ray peaks from the same element, or peaks from different elements). It may be the peak of fluorescent X-rays from ).

(8-2-2) State information obtained from high-energy secondary X-rays This time, when the same particulate matter P was placed on the sample table 15 and secondary X-ray spectra were acquired multiple times, Fig. 6 , the intensity of secondary X-rays (referred to as high-energy secondary X-rays) in an energy range greater than a predetermined threshold value (referred to as first energy Et) fluctuated more greatly in some cases. FIG. 6 is a diagram showing an example in which the intensity of high-energy secondary X-rays changes.
The value of the first energy Et was, for example, 3 keV.

As a result of examination, it was found that there is a correlation between the fluctuations in the intensity of the high-energy secondary X-rays and the height (thickness) of the particulate matter P placed on the sample stage 15 . This correlation indicates that the high-energy X-rays output from the X-ray source 2 propagate to a deeper position (larger thickness position) in the particulate matter P, and from a deep position in the particulate matter P to a high-energy secondary It was found that this was due to the ability to generate X-rays.
The above consideration will be schematically described below with reference to FIG. FIG. 7 is a diagram schematically showing the relationship between the intensity of high-energy secondary X-rays and the thickness of particulate matter.

That is, when the case shown in FIG. 7A is used as a reference, when the thickness of the particulate matter P on the sample stage 15 is large as shown in FIG. Most of the high-energy X-rays are used to generate high-energy secondary X-rays from the particulate matter P because they can propagate deep into the particulate matter P. As a result, the intensity of the high-energy secondary X-rays obtained when the thickness of the particulate matter P is large is greater than the intensity of the high-energy secondary X-rays obtained in the case of (A) in FIG. .

On the other hand, when the thickness of the particulate matter P on the sample table 15 is small as shown in FIG. 7C, most of the X-rays on the high energy side pass through the particulate matter P. Only a small fraction of the X-rays on the side are used to generate high-energy secondary X-rays from the particulate matter P. As a result, the intensity of the high-energy secondary X-rays obtained when the thickness of the particulate matter P is small is lower than the intensity of the high-energy secondary X-rays obtained in the case of (A) in FIG. .

Based on the above principle, the calculation unit 6 uses the characteristic that high-energy secondary X-rays are also generated from the inside of the substance, and based on the intensity of the high-energy secondary X-rays, the sample stage 15 is placed on the Information about the thickness of the particulate matter P can be obtained as state information.

For example, when the intensity of the high-energy secondary X-rays is smaller than a predetermined threshold value, the calculation unit 6 performs an analysis in which the thickness (mounting amount) of the particulate matter P placed on the sample stage 15 is appropriate. can be determined to be insufficient to do.
The above-mentioned "predetermined threshold value" may be, for example, a measured value of the intensity of high-energy secondary X-rays obtained when an appropriate amount of particulate matter P is placed on the sample table 15, or a theoretical calculation It may be a calculated theoretical value. The “predetermined threshold value” is stored in the storage device of the calculation unit 6 .

Further, the calculation unit 6 may acquire the state information based on the intensity of the secondary X-rays at a specific energy value among the high-energy secondary X-rays, or obtain the state information in the energy range of the high-energy secondary X-rays The state information may be acquired using the integrated intensity obtained by integrating the intensity.

In this case, the calculation unit 6 may display, for example, a warning on the display unit 8 or the like that the thickness (mounting amount) of the particulate matter P is insufficient. Thereby, for example, the analysis of the particulate matter P can be started after the loading amount of the particulate matter P reaches a sufficient amount.
Alternatively, the calculation unit 6 simultaneously executes the analysis of the particulate matter P and the acquisition of the state information, and based on the information as to whether the thickness of the particulate matter P grasped from the state information is sufficient or not, responds You may judge whether the analysis of the particulate matter P to carry out is appropriate.

In another embodiment, the computing unit 6 calculates the intensity of the secondary X-rays detected by the detector 3 (in particular, high-energy secondary X-ray intensity) may be corrected.

(8-2-3) State information obtained from low-energy secondary X-rays In addition, when the same particulate matter P was placed on the sample table 15 and secondary X-ray spectra were acquired a plurality of times, Fig. 8 , the intensity of secondary X-rays in the energy range equal to or lower than the first energy Et (referred to as low-energy secondary X-rays) sometimes fluctuates more. FIG. 8 is a diagram showing an example in which the intensity of low-energy secondary X-rays changes.

As a result of examination, it was found that there is a correlation between the intensity fluctuation of the low-energy secondary X-rays and the state of the particulate matter P placed on the sample stage 15 in the vicinity of the sample stage 15 . This correlation indicates that the low-energy X-rays output from the X-ray source 2 propagate only to the vicinity of the sample table 15, and the low-energy secondary X-rays are transmitted only from the particulate matter P existing in the vicinity of the sample table 15. It turned out that this was due to the inability to generate lines.
The above discussion will be schematically described below with reference to FIG. FIG. 9 is a diagram schematically showing the relationship between the intensity of low-energy secondary X-rays and the state of particulate matter in the vicinity of the sample stage.

That is, if the case shown in FIG. 9A is used as a reference, as shown in FIG. Compared to the case of 9 (A), the distance between the surface of the particulate matter P closer to the sample stage 15 and the detector 3 is increased.
Since X-rays on the low-energy side have the property of being difficult to propagate to the inside of the particulate matter P,
The X-rays on the low-energy side reach only the very surface of the particulate matter P. As a result, low-energy secondary X-rays are generated only from the very surface of the particulate matter P. Since the distance between the surface of the particulate matter P closer to the sample table 15 and the detector 3 is large, the intensity of the low-energy secondary X-rays acquired by the detector 3 in this case is as shown in FIG. It is smaller than the intensity of the low-energy secondary X-rays obtained in case (A).

This tendency is also seen when the placement state of the particulate matter P in the vicinity of the sample stage 15 is "rough", that is, when the density of the particulate matter P is low in the vicinity of the sample stage 15 . This is because, in this case, the amount of particulate matter P present in the range that can be reached by low-energy X-rays is small.

On the other hand, as shown in (C) of FIG. 9, when there is (almost) no space in which the particulate matter P does not exist, the amount of particulate matter P is lower than in the case of (A) in FIG. The distance between the surface closer to the sample stage 15 and the detector 3 becomes smaller.
As described above, low-energy secondary X-rays are generated only from the very surface of the particulate matter P, and the distance between the surface of the particulate matter P closer to the sample stage 15 and the detector 3 is small. Therefore, the intensity of the low-energy secondary X-rays acquired by the detector 3 in this case is greater than the intensity of the low-energy secondary X-rays acquired in the case of FIG. 9A.

This tendency is also seen when the placement state of the particulate matter P in the vicinity of the sample table 15 is “dense”, that is, when the density of the particulate matter P is high in the vicinity of the sample table 15 . This is because, in this case, there is a large amount of particulate matter P existing within the reachable range of X-rays on the low-energy side.

Based on the above principle, the calculation unit 6 uses the characteristic that low-energy secondary X-rays are generated on the surface of a substance, and based on the intensity of the low-energy secondary X-rays, particles placed on the sample table 15 Information about the surface state of the material P in the vicinity of the sample stage 15 can be obtained as state information.

For example, when the intensity of the low-energy secondary X-rays is less than a predetermined threshold, the calculation unit 6 cannot perform appropriate analysis because the state of placement of the particulate matter P near the sample stage 15 is inappropriate. can be determined.
The above-mentioned "predetermined threshold value" may be, for example, a measured value of the intensity of low-energy secondary X-rays obtained when the particulate matter P is densely placed on the sample table 15, or may be obtained by theoretical calculation. It may be a calculated theoretical value. The “predetermined threshold value” is stored in the storage device of the calculation unit 6 .

Further, the calculation unit 6 may acquire the state information based on the intensity of the secondary X-rays at a specific energy value among the low-energy secondary X-rays, or in the energy range of the low-energy secondary X-rays The state information may be acquired using the integrated intensity obtained by integrating the intensity.

In this case, the calculation unit 6 may, for example, display a warning on the display unit 8 or the like to the effect that the placement state of the particulate matter P near the sample table 15 is inappropriate. As a result, for example, by vibrating the sample table 15, the placement state of the particulate matter P in the vicinity of the sample table 15 can be improved.

In another embodiment, the computing unit 6 detects by the detector 3 based on the information about the mounting state of the particulate matter P placed on the sample stage 15 in the vicinity of the sample stage 15 acquired by the computing unit 6. The intensity of the received secondary X-rays (particularly the intensity of low-energy secondary X-rays) may be corrected.

(8-3) Summary As described above, the X-ray analysis apparatus 100 according to the first embodiment uses the spectrum of secondary X-rays generated from the particulate matter P placed on the sample stage 15 to detect the sample Information about the thickness of the particulate matter P placed on the table 15 and information about the placement state of the particulate matter P in the vicinity of the sample table 15 can be easily obtained. That is, in the X-ray analysis apparatus 100 according to the first embodiment, it is possible to easily grasp the thickness and placement state of the particulate matter P on the sample stage 15 .
Further, by using this state information, it is possible to determine whether or not the particulate matter P, which is the sample to be measured, is suitable for the fluorescent X-ray analysis.

Furthermore, by acquiring state information using the spectrum of secondary X-rays generated from the particulate matter P, the computing unit 6 obtains information about the thickness of the particulate matter P placed on the sample stage 15 and the sample Information about the placement state of the particulate matter P in the vicinity of the table 15 can be obtained at the same time.

When the elements contained in the particulate matter P to be measured and their contents are known, the calculation unit 6 calculates the intensity of the fluorescent X-ray derived from the element contained in the particulate matter P. to obtain the status information. In the example shown in FIG. 5 and the like, the energy values of the fluorescent X-rays derived from the elements contained in the particulate matter P are energy values E4 and E5.
This is because the intensity of fluorescent X-rays is greater than the intensity of other secondary X-rays (scattered X-rays), so more accurate state information of particulate matter P can be obtained in a short time.

Moreover, since the fluorescent X-rays originating from the target of the X-ray source 2 have a relatively high intensity, the secondary X-rays having the energy value of the fluorescent X-rays originating from the target can be used to acquire the state information.
In the example shown in FIG. 5 and the like, the energy values of the fluorescent X-rays originating from the target are energy values E1 to E3.

On the other hand, if the elements contained in the particulate matter P or their content are unknown, the computing unit 6 can acquire the state information based on the intensity of the scattered X-rays generated from the particulate matter P. .
This is because scattered X-rays are generated regardless of the elements contained in the particulate matter P, so even if there is little information about the particulate matter P, state information about the particulate matter P can be obtained. It is from.

In another embodiment, the computing unit 6 obtains the state information based on the intensity of the secondary X-rays generated from the particulate matter P and the particulate matter P obtained based on the measured quantity other than the secondary X-rays. , and the state of the particulate matter P may be finally determined.
For example, the state of the particulate matter P can be determined using the image of the particulate matter P acquired by the imaging device 9 and the state information. Also, from the image of the particulate matter P, it can be determined whether or not impurities other than the particulate matter P to be measured are included.
In addition, the thickness of the particulate matter P can be accurately determined by combining information on the thickness of the particulate matter P based on secondary X-rays and the thickness measured by another method (ultrasonic wave, laser, etc.). .

In yet another embodiment, acquisition of status information is preferably performed every predetermined time (eg, every hour). Thereby, it is possible to avoid constantly outputting X-rays from the X-ray source 2 . On the other hand, when X-rays may be constantly output from the X-ray source 2, acquisition of status information may be executed constantly.

2. Second Embodiment In the above-described first embodiment, the state information obtained based on the secondary X-rays generated from the particulate matter P is warned as to whether or not the analysis of the particulate matter P is appropriately executed. , and used to correct the intensity of secondary X-rays detected by the detector 3 .
As described above, the state information is information obtained in relation to the location where secondary X-rays are generated, so it can also be used for the purpose of measuring the properties of the particulate matter P placed on the sample stage 15 .

As described in the first embodiment, the low-energy secondary X-rays are emitted from the particulate matter P present in the vicinity of the sample stage 15, that is, from the surface of the particulate matter P placed on the sample stage 15. It occurs. Therefore, low-energy secondary X-rays can be used for the purpose of measuring the surface state of the particulate matter P.

Assuming that the low-energy secondary X-rays are generated from the surface of the particulate matter P, the magnitude of the low-energy secondary X-rays varies depending on the surface area of the particulate matter P placed on the sample stage 15. also change.
Using this principle, the computing unit 6 can acquire information about the surface area of the particulate matter P placed on the sample stage 15 based on the intensity of the low-energy secondary X-rays. Specifically, when the intensity of the low-energy secondary X-rays is high, information indicating that the surface area is large can be obtained, and when the intensity is low, information indicating that the surface area is small can be obtained.

Further, the calculation unit 6 calculates the sample of the particulate matter P from the calibration curve representing the relationship between the surface area and the intensity of the low-energy secondary X-rays and the intensity of the low-energy secondary X-rays obtained by the detector 3. The surface area on the platform 15 side can be calculated.
The calibration curve representing the relationship between the surface area and the intensity of the low-energy secondary X-rays is obtained by placing the particulate matter P on the sample table 15 at a plurality of predetermined surface areas and generating a plurality of secondary X-rays. A spectrum can be acquired, and the intensity of low-energy secondary X-rays among the acquired secondary X-rays can be associated with the surface area value at that time.

The computing unit 6 can acquire information about the particle size of the particulate matter P placed on the sample table 15 based on the intensity of the low-energy secondary X-rays.
For example, if the particle diameters of the particulate matter P are uniform to some extent, the packing rate of the particulate matter P placed on a certain area of the sample stage 15 varies depending on the particle diameter, as shown in FIG. .
Specifically, when the particle diameter is large, the filling rate in a given area decreases ((A) in FIG. 10), and when the particle diameter is small, the filling rate in a given area increases (FIG. 10). (B)).
FIG. 10 is a diagram schematically showing the relationship between the particle size of particulate matter and the filling rate.

When the sample table 15 is filled with the particulate matter P having a large particle diameter at a small filling rate, the surface area of the particulate matter P placed on the fixed area of the sample table 15 becomes small.
On the other hand, when the particulate matter P with a small particle diameter is filled on the sample stage 15 at a high filling rate, the surface area of the particulate matter P in a given area of the sample stage 15 increases.

Using the above principle, as shown in FIG. 11, the calculation unit 6 determines that the particle size of the particulate matter P placed on the sample table 15 is small when the intensity of the low-energy secondary X-ray is large. information can be obtained. Further, when the intensity of the low-energy secondary X-rays is small, it is possible to acquire information that the particle size of the particulate matter P placed on the sample stage 15 is large.
FIG. 11 is a diagram showing the relationship between the particle size of particulate matter and the intensity of low-energy secondary X-rays.

Further, the calculation unit 6 calculates the particulate matter P from the calibration curve representing the relationship between the particle diameter and the intensity of the low-energy secondary X-rays and the intensity of the low-energy secondary X-rays acquired by the detector 3. Particle size can be calculated.
The calibration curve representing the relationship between the particle diameter and the intensity of the low-energy secondary X-rays is obtained by placing particulate matter P having different predetermined particle diameters on the sample stage 15 and generating a plurality of secondary X-rays. A spectrum can be obtained by associating the intensity of low-energy secondary X-rays among the obtained secondary X-rays with the particle size of the particulate matter P at that time.

By using low-energy secondary X-rays, it is possible to measure particle diameters in the order of several tens of μm to several millimeters.

Since the measurement of the particle size using low-energy secondary X-rays is based on the filling rate of the particulate matter P within a certain area, when measuring the particle size, for example, the openings 41, 42 of the opening member 4, 43 is preferably used to keep the irradiation diameter of the X-ray output from the X-ray source 2 constant.
Moreover, in order to appropriately calculate the particle size, it is preferable to irradiate X-rays to at least a region sufficiently larger than the particle size of the particulate matter P to be measured.
Furthermore, in order to accurately measure the particle diameter, it is preferable to irradiate a wide range of the particulate matter P placed on the sample table 15 with X-rays.

Therefore, when measuring the particle diameter, the aperture having the largest diameter (for example, the aperture 43) among the apertures provided in the aperture member 4 can be used to keep the X-ray irradiation diameter constant. preferable.

Furthermore, in order to prevent the X-rays from the X-ray source 2 from reaching a deep position in the particulate matter P placed on the sample stage 15 and secondary X-rays from occurring from the deep position, the X-ray It is preferable to keep the maximum energy of the X-rays generated from the radiation source 2 as small as possible.

Further, the calculation unit 6 calculates the particle Specifically, the thickness of the material P can be calculated.
The calibration curve representing the relationship between the thickness and the intensity of the high-energy secondary X-rays is obtained by placing the particulate matter P on the sample table 15 at a plurality of predetermined thicknesses and generating a plurality of secondary X-rays. A spectrum can be obtained, and the intensity of high-energy secondary X-rays among the obtained secondary X-rays can be associated with the thickness at that time.

3. Other Embodiments Although a plurality of embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the invention. In particular, multiple embodiments and modifications described herein can be arbitrarily combined as needed.
(A) Secondary X-rays generated when X-rays are irradiated to the sample table 15 on which no particulate matter P is placed are used to calibrate the intensity of the X-rays detected by the detector 3. good too.

(B) Depending on the element to be measured and/or the element that is the main component of the particulate matter P, the maximum value of the energy of the X-rays generated from the X-ray source 2 may be changed. When the element to be measured and/or the element that is the main component of the particulate matter P is a heavy element, the maximum value of energy is increased. If the element is light, the maximum energy value is reduced. Thereby, the depth of penetration of the X-rays into the particulate matter P placed on the sample table 15 can be adjusted.
The maximum value of the energy of the X-rays generated from the X-ray source 2 can be obtained, for example, by setting the acceleration voltage of the electrons applied to the target of the X-ray source 2 to a voltage corresponding to the maximum value of the energy of the X-rays to be generated. can be changed.

(C) For example, spectra of secondary X-rays measured in large quantities by in-line measurement and state information obtained using each spectrum may be stored in the storage device of the calculation unit 6 as a database. Then, the spectrum of the secondary X-ray and the corresponding state information may be learned as teaching data. That is, the computing unit 6 may be a learned model formed by this learning.
Thereby, the arithmetic unit 6, which is the learned model, can automatically obtain the state information about the particulate matter P from the obtained secondary X-ray spectrum.

Further, in the above learning, information on the particulate matter P acquired by other means (for example, the imaging device 9, etc.) may be further included as teacher data.
As a result, the computation unit 6, which is a learned model, can automatically acquire state information about the particulate matter P based on the obtained secondary X-ray spectrum and information obtained by other means. For example, from the obtained secondary X-ray spectrum and the image of the particulate matter P, it is possible to automatically determine whether or not impurities are contained.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to an X-ray analysis apparatus that analyzes particulate matter using secondary X-rays generated from the particulate matter, and a particulate matter analysis method.

100 X-ray analysis device 1 sample support section 11 through hole 12 detachable section 13 base section 14 X-ray transparent film 15 sample table 2 X-ray source 21 exit port 3 detector 31 entrance port 4 opening members 41 to 43 opening 44 calibration sample 45 Window part 5 Shield 51 Opening 6 Calculation part 7 Switching part 71 Shaft 8 Display part 9 Imaging element Et First energy P Particulate matter

Claims (13)

An X-ray analyzer for analyzing a sample using fluorescent X-rays generated from the sample,
a sample table on which the sample is placed;
an X-ray source that irradiates the sample placed on the sample table with X-rays;
a detector for detecting secondary X-rays generated by irradiating the sample with the X-rays;
a computing unit that acquires state information about the state of the sample on the sample table based on the intensity of the secondary X-rays detected by the detector;
with
The computing unit determines the state of the sample on the sample stage based on the state information, and analyzes the elements contained in the sample based on whether the state of the sample on the sample stage is appropriate. decide whether or not
The calculation unit generates from the sample existing near the sample stage by irradiating the sample with an X-ray having a low energy that only propagates to the vicinity of the sample stage among the secondary X-rays. Acquiring information about the surface state of the sample placed on the sample stage based on the intensity of the low-energy secondary X-rays;
X-ray analyzer. 2. The X-ray analysis apparatus according to claim 1 , wherein said calculation unit acquires information on the surface area of said sample placed on said sample table based on the intensity of said low-energy secondary X-rays. 3. The X-ray analysis apparatus according to claim 1, wherein said calculation unit acquires information on the particle size of said sample placed on said sample table based on the intensity of said low-energy secondary X-rays. The computing unit acquires information about the thickness of the sample placed on the sample table based on the intensity of high-energy secondary X-rays having energy higher than a first energy among the secondary X-rays. The X-ray analysis apparatus according to any one of claims 1 to 3 . 5. The X-ray analysis apparatus according to any one of claims 1 to 4 , wherein said computing unit acquires said state information based on the intensity of scattered X-rays generated from said sample among said secondary X-rays. The X according to any one of claims 1 to 5 , wherein the computing unit acquires the state information based on the intensity of fluorescent X-rays derived from elements contained in the sample, among the secondary X-rays. Line analyzer. a calibration sample for calibrating X-rays detected by the detector;
an aperture member provided with an aperture through which X-rays generated from the X-ray source pass;
a switching unit for switching and arranging the calibration sample or the aperture of the aperture member between the X-ray source and the sample stage;
The X-ray analysis apparatus according to any one of claims 1 to 6 , further comprising: The X-ray analysis apparatus according to any one of claims 1 to 7 , wherein at least the surface of said sample table on which said sample is placed has conductivity. 9. The X-ray analysis apparatus according to claim 8 , wherein the surface of said sample stage is coated with a conductive material. 10. The X-ray analysis apparatus according to claim 9 , wherein the material coated on the surface of said sample stage is a conductive metal or diamond-like carbon. 11. The X-ray analysis apparatus according to any one of claims 8 to 10 , wherein said sample table is made of conductive metal or graphite. A method for analyzing a sample using an X-ray analyzer equipped with a sample stage,
irradiating the sample placed on the sample table with X-rays;
detecting secondary X-rays generated by irradiating the sample with the X-rays;
acquiring state information about the state of the sample on the sample table based on the intensity of the detected secondary X-rays;
Determining the state of the sample on the sample stage based on the state information, and determining whether to analyze the elements contained in the sample based on whether the state of the sample on the sample stage is appropriate. a step;
including
In the step of acquiring the state information, among the secondary X-rays, the secondary X-rays, which have low energy and propagate only to the vicinity of the sample stage, are irradiated to the sample so that the X-rays existing in the vicinity of the sample stage Acquiring information about the surface state of the sample placed on the sample stage based on the intensity of low-energy secondary X-rays generated from the sample;
Analysis method. irradiating the sample placed on the sample table with X-rays;
detecting secondary X-rays generated by irradiating the sample with the X-rays;
acquiring state information about the state of the sample on the sample table based on the intensity of the detected secondary X-rays;
Determining the state of the sample on the sample stage based on the state information, and determining whether to analyze the elements contained in the sample based on whether the state of the sample on the sample stage is appropriate. a step;
including
In the step of acquiring the state information, among the secondary X-rays, X-rays having low energy that propagate only up to the vicinity of the sample stage are irradiated to the sample, and the X-rays existing in the vicinity of the sample stage Acquiring information about the surface state of the sample placed on the sample stage based on the intensity of low-energy secondary X-rays generated from the sample;
A program that causes a computer to carry out an analysis method .

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