JPH0755734A - Automatic qualitative analyzer for x-ray microanalyzer and the like - Google Patents

Abstract

PURPOSE:To improve the accuracy of automatic qualitative analysis by computing the certainty of the presence of each element in a semi-quantitative manner and deciding the presence of the elements on the basis of the certainty of the presence. CONSTITUTION:Element identification processing means 3, 4, in which the peak of a spectrum is detected and elements are identified and processed by qualitative analysis while referring to a wavelength, the elements and the table of characteristic X-rays, certainty arithmetic means 5, 6, in which positive certainty affirming the presence of the elements and negative certainty by superposition with other high-order rays or contradiction are obtained regarding the Kalpha-, Lalpha-or Malpha-rays and Kbeta-,Lbeta-or Mbeta-rays of the spectrum as the base of the identification of the identified elements and the peaks of these high-order rays and the presence certainty of the presence of the elements is acquired in a semi- quantitative manner by the total of both certainty, and a decision means 7 deciding the presence or absence of the elements from the value of presence certainty obtained are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention scans a wavelength dispersive X-ray spectroscope having a plurality of dispersive crystallographic crystals, detects characteristic X-rays from a sample, and collects a plurality of spectra. The present invention relates to an automatic qualitative analyzer such as a line microanalyzer.

[0002]

2. Description of the Related Art FIG. 5 is a diagram showing the outline of the structure of an X-ray microanalyzer, etc., 11 is a filament, 12 is Wehnelt, 13 is an electron beam, 14 is a converging lens, 15 is an objective lens, 16 is a sample, 17 Is a sample stage, 18 is a dispersive crystal, 19 is an X-ray, 20 is a detector, 21 is a mouse,
Reference numeral 22 is a spectrometer controlled X-ray measurement unit, 23 is a data processing device, 24 is a display device, and 25 is a keyboard.

EPMA (X-ray microanalyzer) is
Irradiate the sample surface with an electron beam and detect the characteristic X-rays generated from it to observe the sample surface, analyze the concentration of composition elements,
It is possible to display a color image in an element distribution state. The structure is as shown in FIG.
1, Wehnelt 12, convergent lens 14, objective lens 15
To generate an electron beam 13 that is narrowed down in a vacuum and irradiates the unknown sample 16 held on the sample stage 17 with a wavelength-dispersive X-ray having a plurality of dispersive crystallographic crystals 18.
The characteristic X-ray 19 generated from the unknown sample 16 is detected by the detector 20 by scanning the line spectroscope, and a plurality of spectra are collected by the spectroscope control X-ray measurement unit 22 and taken into the data processing device 23 to identify the element. Processing etc.

In automatic qualitative analysis in an X-ray microanalyzer or the like using a conventional wavelength dispersive X-ray spectrometer, a plurality of data collected in the spectroscope-controlled X-ray measuring unit 22 using the wavelength dispersive X-ray spectrometer. Spectrum processing device 2
3, the peaks in the spectrum are detected as proposed in Japanese Patent Laid-Open No. 63-58240, and Kα, Kβ, Lα, L of all elements are contained in each peak.
X-rays such as β, Mα, and Mβ were assigned, and elements existing in the sample were identified from the types of those X-rays. Specifically, by obtaining wavelength data of characteristic X-ray data from a plurality of spectral data collected simultaneously by using a plurality of X-ray spectroscopes, the wavelength data and the primary line data of each element stored in advance are obtained. And the K of a particular element,
The presence of the identifying element was determined by determining the peak wavelength positions of the α and β rays of L and M.

[0005]

However, in the above-mentioned conventional method, for elements present in large amounts in unknown samples,
Although it is possible to almost certainly determine its existence, it was sometimes erroneously determined that even elements that should not exist at all often exist due to the influence of sub-lines or higher-order lines of those elements. Further, since the characteristic X-ray itself used for the judgment exists or does not exist, there is no standard for judging how confident the existence of a trace element can be claimed. It was Therefore, there was a limit in trying to improve the accuracy of the qualitative analysis.

The present invention is to solve the above-mentioned problems, and it is possible to semi-quantitatively calculate the certainty factor of the existence of each element and to judge the presence of the element based on this certainty factor. An object of the present invention is to provide an automatic qualitative analysis device such as an X-ray microanalyzer capable of improving the accuracy of automatic qualitative analysis.

[0007]

To this end, the present invention scans a wavelength dispersive X-ray spectroscope having a plurality of dispersive crystallographic crystals to detect characteristic X-rays from a sample and obtain a plurality of spectra. An automatic qualitative analysis device such as an X-ray micro-analyzer for collecting, and an element identification processing means for performing element identification processing by qualitative analysis by detecting a peak of a spectrum and referring to a table of wavelengths, elements and characteristic X-rays, The Kα, Lα or Mα line, Kβ, Lβ or Mβ line of the spectrum on which the identification of the identified element was based, and the positive confidence and other positive affirmation of the presence of the element for these higher order peaks. A certainty factor calculation means for semi-quantitatively obtaining the certainty factor for existence of an element by obtaining the negative certainty factor due to overlap or contradiction with a higher-order line, and the existence or non-existence of the element from the obtained value of the certainty factor. Those, wherein further comprising a determining means for determining standing.

[0008]

In the automatic qualitative analysis apparatus such as the X-ray microanalyzer of the present invention, an element identification processing means for detecting the peak of the spectrum and performing the element identification processing by the qualitative analysis by referring to the table of wavelengths, elements and characteristic X-rays. , Kα, Lα or Mα of the spectrum on which the identification of the identified element was based
Line, Kβ, Lβ or Mβ line, and the positive certainty that affirms the existence of the element for the peaks of these higher-order lines and the negative certainty due to the overlap or inconsistency with other higher-order lines, A certainty factor calculation means for semi-quantitatively determining the existence certainty factor of an element and a determination device for determining the existence or non-existence of an element from the obtained existence certainty factor value are used. By using this, it is possible to more semi-quantitatively calculate the existence certainty factor for each element, and it is possible to determine the presence or absence of an element based on this existence certainty factor.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an automatic qualitative analyzer such as an X-ray microanalyzer according to the present invention, and FIG. 2 is a flow chart for explaining an element identification flow by the automatic qualitative analyzer such as an X-ray microanalyzer according to the present invention. FIG. In the figure,
1 is a spectrometer control X-ray measurement unit, 2 is a spectrum data storage memory, 3 is an element identification processing unit, 4 is a wavelength table, 5 is a certainty factor calculation unit, 6 is a certainty factor table, and 7 is a determination unit.

In FIG. 1, a spectroscope-controlled X-ray measuring unit 1 scans a wavelength-dispersive X-ray spectrometer having a plurality of dispersive crystallographic crystals to detect characteristic X-rays from a sample. , A plurality of spectra are collected, and the spectrum data storage memory 2 stores a plurality of collected spectrum data. The wavelength table 4 stores wavelengths, elements, and characteristic X-ray names,
The element identification processing section 3 detects peaks from a plurality of spectra stored in the spectrum data storage memory 2, and refers to the wavelength table 4 for each of these peaks to identify elements. The certainty factor table 6 shows the element α,
The certainty factor that β-rays exist, the certainty factor that a secondary ray of an element exists, the certainty factor that overlaps with X-rays of other elements, the certainty factor that there is a contradiction between the X-ray intensities of elements, and the peak half width is It stores information for calculating an abnormal certainty factor, and Kα, Lα or Mα ray of the spectrum, Kβ, which is the basis of the identification of the element identified by the element identification processing unit 3.
For the Lβ or Mβ line and the peaks of these higher-order lines, information of the positive certainty factor affirming the existence of the element and the negative certainty factor due to the overlap or contradiction with other higher-order lines is stored. The certainty factor calculation unit 5 calculates the certainty factor for each element identified by the element identification processing unit 3 by referring to the certainty factor table 6, and obtains the total certainty factor (presence factor). The determination unit 7 determines the presence or absence of an element from the value of the existence certainty factor calculated by the certainty factor calculation unit 5.

Next, the element identification flow by the automatic qualitative analyzer having the above-mentioned structure will be described with reference to FIG. First, when a plurality of spectra are collected by the spectroscope-controlled X-ray measurement unit 1 and stored in the spectrum data storage memory 2, peak detection is performed as in the conventional qualitative identification, and then the wavelength table 4 is referred to for each peak. Then, α ray and β ray assignments and element identification are performed (steps S1 to S4). If there are n elements identified by this element identification, i =
After being set to 1 (step S5), the α ray of the i-th element,
The certainty factor that β-rays and secondary rays exist is calculated (step S
6-S8). Furthermore, the certainty factor that overlaps with the higher-order X-rays of other identified elements, the certainty factor that there is a contradiction between the X-ray intensities of the i-th element, and the certainty factor that the peak half width is not normal are calculated (step S9-S11). Then, the certainty factors obtained in the processes of steps S6 to S11 are summed to obtain the presence certainty factor of the i-th element, and the presence or absence of the element is determined from the value of the certainty factor (step S1).
2). Then, i is incremented by 1 to i = i + 1, i is compared with n (steps S13 to S14), and the processes of steps S6 to S12 are repeated until the identified element number n is reached.

In carrying out the above qualitative analysis, a certainty factor for asserting the existence of an element from a generally observed spectrum is given as follows. In addition,
The value of the certainty factor usually takes a value from 0 to 1, but −100
You may define a negative value as a value from 1 to 100 and negate the existing value.

Confidence that there is an α-ray peak of K, L or M. However, which of K, L, and M (or both) lines are taken depends on the atomic number of the element and the acceleration voltage. Generally, the peak X-ray intensity is P, and the background average X-ray intensity before and after the peak is B.
Then, the average statistical variation (standard deviation) σ of the X-ray net intensity P ₀ = P−B is given by σ = (P−B) / (P + B / 2) ^1/2 . Therefore, when t is defined as P ₀ = σt, the certainty (confidence) that a peak exists is given as a function of t, and the larger the value of t, the higher the certainty that the peak exists. The certainty factor with a peak can be obtained by calculation as a function of t, but since the calculation takes a long time, the certainty factor can be calculated in 3 to 4 steps with a value of about t = 1, 2, 3 as a guide. It may be obtained separately, or empirical values may be substituted for practically no problem.

The certainty factor that when the K (or L, M) α ray exists, the β ray accompanying it also exists. This certainty factor depends on the net X-ray intensity of β-rays, and if the X-ray intensity ratio satisfies the relationship of α-ray> β-ray, its peak exists, and the certainty factor that it is due to β-rays is Get higher

The certainty factor that when a K (or L, M) α ray exists, a secondary ray associated with it also exists. This certainty factor also depends on the net X-ray intensity of the peak of the secondary line, and
If the line intensity ratio satisfies the relationship of α-ray intensity> secondary line intensity, the peak exists, and the certainty factor that it is due to the secondary line is high.

When a K (or L, M) α ray of an element A exists, that line is K (or L, M) of another element B.
M) α-rays, or other sub-primary rays or higher-order rays (interfering rays), the larger the net X-ray of the K (or L, M) α-rays of the element B, the larger the element B.
The certainty that the element A exists is higher, and conversely, the certainty that the element A exists is reduced accordingly. In this case, the degree of reduction depends on the orders of higher-order rays of other elements, and when sub-rays other than α-rays have the same order, the degree depends on the relative intensity of those rays with respect to α-rays. . However, it is important that the main line (Kα line or the like) that is the basis of the existence of the element B itself does not overlap with the higher order line of another element.

Although the Lα ray was present but overlapped with other disturbing rays, it was not detected even though the Kα (or Lβ) ray satisfied the sufficient detection condition, and similarly, the Mα ray was also present. , If it is not detected even though it overlaps with some X-ray of another element and the Lα (or Mβ) ray satisfies the detectable condition, it causes a contradiction in the existence of that element itself. Think that there is. Therefore, the confidence that the peak in question is due to another element is increased. Therefore, the certainty factor that is the peak of the element is reduced.

Characteristic X generated from light elements such as Be to F
The full width at half maximum of a line is generally observed to be larger than the full width at half maximum of a characteristic X-ray generated from an element having a larger atomic number, and the higher-order lines of those X-rays often overlap with the X-ray of a light element. Therefore, although the light element does not actually exist, it may be determined that it exists because of the higher order line of other elements. In order to prevent this, if the magnitude of the full width at half maximum is less than a certain value, the possibility of the influence of higher-order lines increases, and thus the certainty factor that the light element exists is reduced.

The condition for setting the certainty factor as described above is obtained to determine whether or not the element in question actually exists. For that purpose, these certainty factors are combined. In order to easily perform this synthesis, the case where the above ,,, or is satisfied is calculated as the positive certainty factor, and the calculation is performed based on the data such as the detected X-ray intensity. Intensity of main X-rays (α rays of K, L, M) of other elements that are the source of interference line, degree of interference line, relative intensity, etc. Find the total of degrees. Also, if it is difficult to calculate the exact confidence value for each element,
You may use the numerical value which can be judged to be reasonable from experience.

Whatever method is used, if the numerical value is reliable to some extent, the existence of the element is numerically divided into numerical levels according to the numerical value of the total confidence value, and there is A rank as a surely existing element. By classifying the possible elements into ranks such as B rank, it becomes possible to perform more accurate judgment analysis as a result.

FIG. 3 is a diagram showing an example of a qualitative analysis spectrum of Fe, Cu and S, and FIG. 4 is a diagram showing an example of a qualitative analysis result of Fe, Cu and S.
This is an example using T and TAP.

As a concrete example, a plurality of substances collected from a substance containing Fe, Cu and S (CuFeS2) by scanning with a wavelength dispersive X-ray spectrometer having a plurality of dispersive crystal LIFs, PET and TAP. FIG. 3 shows an example of the spectrum, and FIG. 4 shows a value for each peak obtained by qualitative analysis of the spectrum. Thus, if Fe, Cu, and S are sufficiently contained in the sample, Fe, Cu, and S are all Kα.
The X-ray intensities of the peaks of the X-rays, Kβ rays, and Kα secondary rays are sufficiently higher than the background X-rays. Then, for Fe, Cu, and S, the positive certainty factor of, is sufficiently high, but the negative certainty factor of, remains zero. On the other hand, for P, a positive certainty factor was obtained because the first-order line of Kα of P and a fourth-order line of Kα of Cu were overlapped, but to obtain a negative certainty factor, the total was obtained. The certainty factor is close to 0 because positive and negative cancel each other out. As a result, Fe, Cu, and S exist, and the existence of P is denied.

Although the above example is a simple case, even for a delicate element judgment including a large number of trace elements, the peak existence certainty factor is taken into consideration as compared with the conventional simple judgment, so that an accurate judgment result is obtained. Can be guided.

[0024]

As is clear from the above description, according to the present invention, the presence of an element is determined based on the certainty (certainty) of the existence of a peak, so that there is no conventional peak. It is possible to make a more reliable judgment than the binary judgment. In addition, if the primary line of the Kα (or Kα, Mα) line that is the basis of the existence of an element overlaps with another higher-order line, a negative value is given to the existence certainty factor of the element, so that If there is no other basis for supporting the existence of the element (for example, β-rays or secondary rays), the certainty of the existence of the element decreases, and the existence of the element may be denied. Of course, if there is any other reason to affirm the existence of the element, the existence of the element will be affirmed because a positive certainty factor can be obtained. Therefore, a proper judgment can always be obtained. Further, the method of giving the confidence is ideally obtained by rigorous calculation, but when it is impossible, empirical numerical values can be used instead. Moreover, by using empirical numerical values, it is possible to avoid cases that are often erroneously typical in qualitative identification.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an automatic qualitative analyzer such as an X-ray microanalyzer according to the present invention.

FIG. 2 is a diagram for explaining an element identification flow by an automatic qualitative analyzer such as an X-ray microanalyzer according to the present invention.

FIG. 3 is a diagram showing an example of a spectrum of qualitative analysis of Fe, Cu, and S.

FIG. 4 is a diagram showing an example of a qualitative analysis result of Fe, Cu, and S.

FIG. 5 is a diagram showing a schematic configuration of an X-ray microanalyzer or the like.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Spectrometer control X-ray measurement unit, 2 ... Spectral data storage memory, 3 ... Element identification processing part, 4 ... Wavelength table, 5 ... Certainty factor calculation part, 6 ... Certainty factor table, 7 ... Judgment part

Claims (1)

[Claims] 1. An automatic X-ray microanalyzer or the like for scanning a wavelength dispersive X-ray spectroscope having a plurality of dispersive crystallographic crystals to detect characteristic X-rays from a sample and collecting a plurality of spectra. A qualitative analysis device, which is an element identification processing means for detecting peaks in a spectrum and performing element identification processing by qualitative analysis by referring to a table of wavelengths, elements and characteristic X-rays, and a basis for identification of identified elements. Kα, Lα or Mα ray, Kβ, Lβ or Mβ ray of the spectrum, and the positive certainty affirming the existence of the element for the peaks of these higher-order lines and the negativeness due to the overlap or discrepancy with other higher-order lines. And a determination means for determining the existence or non-existence of the element from the value of the determined presence certainty factor, and a semi-quantitative determination factor for determining the certainty factor of the existence of the element. Octopus An automatic qualitative analyzer such as an X-ray microanalyzer characterized by