JP2001050917A - X-ray fluorecsence analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an X-ray fluorescence analyzer by which the series of characteristic X-rays to be used regarding an element to be quantitatively analyzed can be selected automatically and properly, by taking the S/N ratio into consideration on the basis of the result of a qualitative analysis. SOLUTION: A decision means 13 by which the series of characteristic X-rays to be used regarding an element to be analyzed quantitatively is decided on the basis of the comparison of the measuring intensity of the scattered radiation of primary X-rays 3 scattered by a sample with a prescribed reference line is provided. By the decision means 13, the series of the characteristic X-rays to be used regarding the element to be analyzed quantitatively is selected properly by taking S/N ratio into consideration, a detection limit becomes low, and the element can be analyzed simply and precisely. In addition, even regarding a heavy element in a sample composed mainly of a light element, characteristic X-rays in a series which easily reaches a saturation thickness in terms of X-rays are selected by the decision means 13, an error due to the thickness of the sample is hard to generated, and the element can be analyzed simply and precisely in this respect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for obtaining a quantitative analysis value from a qualitative analysis result in an X-ray fluorescence analyzer.

[0002]

2. Description of the Related Art Conventionally, so-called wavelength-dispersive fluorescent X
In X-ray analysis, primary X-rays are applied to a sample from an X-ray source such as an X-ray tube.
The sample is irradiated with X-rays, and the fluorescent X-rays generated from the sample are diffracted (spectralized) by a spectroscopic element, and the fluorescent X-rays diffracted by the spectroscopic element are detected by a detector. Here, in the qualitative analysis, the spectroscopic element and the detector are continuously linked by a linking means called a goniometer so that the wavelength of the fluorescent X-rays incident on the detector is changed, so that each element contained in the sample is removed. The generated fluorescent X-rays are separated into respective wavelengths and detected.

[0003] It has become common practice to perform peak search and identification analysis on the spectrum indicating the intensity of fluorescent X-rays obtained at each spectral angle, and to obtain quantitative analysis values from the results of the qualitative analysis. . At this time, in consideration of the sensitivity (detected intensity) in an experiment using a representative sample, the overlap of adjacent fluorescent X-rays, and the like, the elements to be quantitatively analyzed are uniformly Be atoms having atomic numbers of 4 to 55. ~ Cs
Element, K-series characteristic X-rays are used, and the atomic numbers are 56 to
For the elements Ba to U of 92, calculations were performed using characteristic X-rays of the L series.

[0004]

However, the selection of such a series is not always appropriate. For example, cesium (Cs, atomic number 5
When the Cs-Kα ray is used in the quantitative analysis of 5), the background intensity is large, so that the SN ratio is low (bad), the detection limit is high, and accurate analysis cannot be performed. In such a case, the strength may be slightly lower,
Cs-Lα rays having a low background intensity, that is, a high SN ratio should be used.

[0005] Such a problem is caused by the fact that, in a sample containing a light element as a main component, Compton scattered rays and continuous X-ray scattered rays are generated strongly on the short wavelength side, and the background intensity is increased. However, it is often not easy for an operator to appropriately judge a characteristic X-ray sequence to be used for an element to be quantitatively analyzed in consideration of such circumstances.

The present invention has been made in view of the above-mentioned conventional problems. Based on the results of qualitative analysis, a series of characteristic X-rays to be used for an element to be quantitatively analyzed is automatically and appropriately considered in consideration of an SN ratio. It is an object to provide a fluorescent X-ray analyzer that can be selected.

[0007]

In order to achieve the above object, a first invention of the present application is an apparatus for measuring the intensity of secondary X-rays generated by irradiating a sample with primary X-rays, A determination means is provided for determining a series of characteristic X-rays to be used for an element to be quantitatively analyzed based on a comparison between a measured intensity of scattered primary X-rays scattered by the sample and a predetermined reference value.

According to the first aspect of the present invention, a series of characteristic X-rays to be used for an element to be quantitatively analyzed is appropriately selected in consideration of the SN ratio by the determining means, and the detection limit is lowered. Accurate analysis can be performed. In addition, for the heavy element in the sample containing a light element as a main component, a series of characteristic X-rays that easily reach a saturated thickness on the X-ray is selected by the determination means, and an error due to the thickness of the sample occurs. Since it is difficult, accurate analysis can be easily performed in this respect as well. Here, Compton scattered radiation can be used as the scattered radiation.

The second invention of the present application relates to an X-ray fluorescence analyzer for measuring the intensity of secondary X-rays generated by irradiating a sample with primary X-rays, wherein the characteristics of the elements to be quantitatively analyzed are different from each other. There is provided a judging means for judging a series of characteristic X-rays to be used for the element to be quantitatively analyzed, based on a ratio of measured intensities of the X-ray and respective backgrounds. According to the second invention of the present application, the same operation and effect as those of the first invention are obtained.

In the present invention, it is preferable that the atomic number of the element to be judged by the judgment means is in the range of 48 to 58. This is because it is usually unnecessary to judge elements outside the range. Further, the characteristic X-ray sequence to be determined by the determining means is a K sequence and an L sequence.
It is preferably a series. This is because M-series and N-series characteristic X-rays usually have extremely low intensity and are unsuitable for quantitative analysis.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to an embodiment of the present invention will be described below. 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, an X-ray source 4 such as an X-ray tube for irradiating the sample 1 with primary X-rays 3, and a secondary X-ray 5 generated from the sample 1. Element 6 and secondary X-rays 7 separated by the element 6
And a detector 8 for measuring the intensity of the light. The secondary X-rays 5 and 7 include fluorescent X-rays generated from the sample 1 and
The scattered radiation of the continuous X-ray of the primary X-ray 3 and the scattered radiation of the characteristic X-ray of the primary X-ray 3 are included.

Further, there is provided a linking means 10 for linking the spectroscopic element 6 and the detector 8 so as to change the wavelength of the secondary X-ray 7 incident on the detector 8, that is, a so-called goniometer. When the secondary X-rays 5 enter the spectroscopic element 6 at a certain incident angle θ, an extension line 9 of the secondary X-rays 5 and the secondary X-rays 7 spectrally (diffracted) by the spectroscopic element 6 have an incident angle θ of 2 Double spectral angle 2
θ, but the interlocking means 10 changes the spectral angle 2θ to change the wavelength of the secondary X-rays 7 to be split, so that the split secondary X-rays 7 enter the detector 8. , The spectroscopic element 6 is rotated about an axis O perpendicular to the plane of the drawing passing through the center of the surface, and the detector 8 is rotated by an angle O twice the rotation angle.
Is rotated along the circle 11 around. In the interlocking means 10, the incident angle θ and the spectral angle 2θ formed as a result of rotation of the spectroscopic element 6 and the detector 8 are confirmed by, for example, a potentiometer attached to the axis O.

The apparatus further comprises a control processing means 15 including the following qualitative analysis means 12, judgment means 13 and quantitative analysis means 14. The qualitative analysis means 12 performs the measurement at each spectral angle 2θ obtained using the interlocking means 10.
The spectrum showing the intensity of the next X-ray 7 is subjected to peak search and identification analysis, and the result of the qualitative analysis is stored.

The determining means 13 determines the measured intensity of the scattered radiation of the primary X-ray 3 scattered by the sample 1, specifically, the characteristic X-ray of the primary X-ray 3, and a predetermined reference value. Based on the comparison, the sequence of characteristic X-rays to be used for the element to be quantitatively analyzed (the element whose content has been recognized in the qualitative analysis) is determined. The predetermined reference value can be obtained in advance by an experiment as described later. Here, the characteristic X-ray of the primary X-ray 3 refers to a Rh-Kα ray having a high intensity among fluorescent X-rays generated from rhodium when the X-ray source 4 is an X-ray tube targeting rhodium. . Also,
As the scattered X-rays of the characteristic X-rays of the primary X-rays 3, Compton scattered rays of Rh-Kα rays whose intensities change greatly under the influence of the density of the sample 1 are used.
Thomson scattering rays of α-rays may be used, or continuous X-rays of primary X-rays 3 may be used.

As a sequence of characteristic X-rays to be judged, a K sequence and an L sequence are employed. This is because M-series and N-series characteristic X-rays usually have extremely low intensity and are unsuitable for quantitative analysis. As the characteristic X-rays of the K series and the L series, Kα rays and Lα rays having higher intensities than Kβ rays and Lβ rays are used, but Kβ rays and Lβ rays may be used. The above determination is made only when the atomic number of the element to be quantitatively analyzed is in the range of 48 to 58 (Cd to Ce). The determination of elements having other atomic numbers is usually unnecessary, so that the sequence is determined uniformly as in the conventional case. That is, the atomic number is 4 to 4
For the elements Be to Ag of No. 7, K-series Kα rays are used, and for the elements Pr to U of atomic numbers 59 to 92, the L-series Lα rays are used. However, the range of the atomic number of the element to be determined is within the range of 48 to 58,
More specifically, for example, the range can be set to 49 or more and 55 or less. In this case, the atomic number is 48, 56 to 58
The elements are uniformly determined in the same manner as in the prior art.

The quantitative analysis means 14 calculates, for the element to be quantitatively analyzed, the measured intensity of the characteristic X-rays of the series selected by the determination means 13 or the measured intensity of the characteristic X-rays of the series determined uniformly. The quantitative analysis value (content rate) of each element is calculated by the fundamental parameter method by using it by calling it from the qualitative analysis means 12. The measured intensity of each fluorescent X-ray is a net intensity obtained by subtracting the corresponding background intensity.

Next, the operation of this device will be described.
The sample 1 is placed on the sample stage 2, and the sample 1 is
When the secondary X-ray 3 is irradiated, the secondary X-ray 5 generated from the sample 1 is separated by the spectroscopic element 6, and the intensity of the split secondary X-ray 7 is measured by the detector 8. Here, the qualitative analysis means 12
However, by continuously interlocking the spectroscopic element 6 and the detector 8 with the interlocking means 10, the secondary X-rays 5 generated from the sample 1 are separated into respective wavelengths, detected, and detected at each spectral angle 2θ. A spectrum indicating the intensity of the next X-ray 7 is obtained. The qualitative analysis means 12 performs peak search and identification analysis on this, and stores the result of the qualitative analysis. Now, if the sample 1 is mainly composed of a light element such as cement or a polymer, the result of the qualitative analysis will be as shown by a solid line in FIG. 2, for example. Here, wavelength is used on the horizontal axis. In FIG. 2, for simplicity, only the spectrum of cesium among the elements whose content is recognized in the qualitative analysis, that is, the elements to be quantitatively analyzed, and the spectra of other contained elements are omitted. ing.

In the quantitative analysis of the sample 1, as described above, Cs-Kα radiation was used uniformly for cesium (atomic number 55) from the viewpoint of sensitivity (intensity) and the like as described above. In sample 1 containing an element as a main component, the intensity of the background of Cs-Kα rays (scattered X-rays of primary X-rays) is large, so that the SN ratio is low (poor) and the detection limit is high. , Accurate analysis is not possible.

On the other hand, in this apparatus, the judgment means 13
However, as shown by the solid line in FIG. 2, since the measured intensity (gloss intensity of the peak) of the Compton scattered radiation of the Rh-Kα ray exceeds a predetermined reference value R, Cs- is used as the characteristic X-ray of cesium used in the quantitative analysis. Select the Lα line. The reference value R is R
When the measured intensity of the h-Kα ray Compton scattered ray exceeds this, in each element having an atomic number of 48 to 58, the SN ratio of the L-series Lα ray becomes higher than that of the K-series Kα ray. As described above, the values may be obtained in advance through experiments and set. The determination means 13 determines that the atomic number is
In the range of 8 or less, Lα rays are selected as characteristic X-rays to be used for other elements to be quantitatively analyzed.

When the atomic number of the element to be quantitatively analyzed is in the range of 48 to 58, the quantitative analysis means 14 determines the measured intensity of the L-series Lα line selected by the determination means 13 and the atomic number of 4 to 47. In the range of, the measured intensity of Kα ray of K series, which is determined uniformly as in the past,
Even when the atomic number is in the range of 59 to 92, the measured intensity of the L-series Lα line, which is determined uniformly as in the past, is called from the qualitative analysis means 12 and used, and the quantitative analysis value ( Content).

On the other hand, if the sample 1 contains a heavy element as a main component, the result of the qualitative analysis is, for example, as shown by a broken line in FIG. In this case, since the measured intensity of the Compton scattered radiation of the Rh-Kα ray is equal to or less than the predetermined reference value R, the determination means 13 selects the Cs-Kα ray as the characteristic X-ray of cesium used for the quantitative analysis. Atomic number 48 or more 58
In the following range, Kα rays are selected as characteristic X-rays to be used for other elements to be quantitatively analyzed.

When the atomic number of the element to be quantitatively analyzed is in the range of 48 to 58, the quantitative analysis means 14 determines the measured intensity of the K series Kα ray selected by the judgment means 13 and the atomic number of 4 to 47. In the range of, the measured intensity of Kα ray of K series, which is determined uniformly as in the past,
Even when the atomic number is in the range of 59 to 92, the measured intensity of the L-series Lα line, which is determined uniformly as in the past, is called from the qualitative analysis means 12 and used, and the quantitative analysis value ( Content).

As described above, according to the device of the present embodiment,
By the judging means 13, the characteristic X-ray sequence to be used for the element to be quantitatively analyzed is appropriately selected in consideration of the SN ratio, and the detection limit is lowered, so that accurate analysis can be easily performed. Further, in the sample 1 containing a light element as a main component, when Cs-Kα rays are uniformly used as characteristic X-rays of cesium in the quantitative analysis as in the related art, the sample 1 has a thickness of, for example, 1 cm and a bulk sample in appearance. Even though it seems to have a sufficient thickness, it may not reach the saturation thickness in X-ray, and in such a case, the thickness affects the measurement intensity, so it is treated as a thin film sample. If not, analysis cannot be performed correctly. On the other hand, according to the apparatus of the present embodiment, the determining means 13 selects a characteristic X-ray of a series that easily reaches a saturated thickness in the X-ray, such as a Cs-Lα ray, and In this respect, an accurate analysis can be easily performed.

In the present embodiment, the judgment means 13
The sequence of characteristic X-rays to be selected was determined by comparing the measured intensity of scattered X-ray scattered radiation of primary X-rays (Compton scattered radiation of Rh-Kα ray) with a predetermined reference value R. Alternatively, the sequence may be determined as follows. That is, the determination means obtains the ratio between the measured intensity of the characteristic X-ray of the K-series characteristic X-ray (the peak gross intensity) of the element to be quantitatively analyzed and the measured intensity of the corresponding background, and determines the characteristic of the L-series characteristic of the same element The ratio between the measured intensity of the X-ray (the gross intensity of the peak) and the corresponding measured intensity of the background is determined, and the SN
The characteristic X-ray of the series having the higher ratio may be selected. In this case, since the determination is made for each element, the procedure in the determination means is increased, but more accurate analysis can be performed.

[0025]

As described above in detail, according to the present invention, the characteristic X-ray sequence to be used for the element to be quantitatively analyzed is appropriately selected by the judgment means in consideration of the SN ratio, and the detection limit is obtained. , So that accurate analysis can be easily performed. In addition, for the heavy element in the sample containing a light element as a main component, a series of characteristic X-rays that easily reach a saturated thickness on the X-ray is selected by the determination means, and an error due to the thickness of the sample occurs. Since it is difficult, accurate analysis can be easily performed in this respect as well.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an X-ray fluorescence analyzer according to one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a result of qualitative analysis by the same device.

[Explanation of symbols]

1: Sample, 3: Primary X-ray, 4: X-ray source, 5, 7: Secondary X-ray
Line, 13: determination means, R: reference value.

Claims (4)

[Claims] An X-ray fluorescence spectrometer for measuring the intensity of secondary X-rays generated by irradiating a sample with primary X-rays, wherein the measured intensity of primary X-rays scattered by the sample and a predetermined intensity are measured. An X-ray fluorescence spectrometer, comprising: a determination unit configured to determine a series of characteristic X-rays to be used for an element to be quantitatively analyzed based on a comparison with a reference value. 2. The X-ray fluorescence analyzer according to claim 1, wherein the scattered radiation is Compton scattered radiation. 3. An X-ray fluorescence spectrometer for measuring the intensity of secondary X-rays generated by irradiating a sample with primary X-rays, wherein characteristic X-rays having different series of elements to be quantitatively analyzed and their respective backgrounds are provided. A determination unit for determining a series of characteristic X-rays to be used for an element to be quantitatively analyzed based on a ratio of measured intensities to the fluorescent X-ray.
Line analyzer. 4. The element according to claim 1, wherein the atomic number of the element to be judged by the judgment means is 48.
An X-ray fluorescence analyzer in which the characteristic X-rays to be judged by the judging means are K series and L series.