JP3143276B2 - Automatic qualitative analyzer such as X-ray micro analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray apparatus for detecting a characteristic X-ray from a sample by scanning a wavelength dispersive X-ray spectrometer having a plurality of dispersive crystals having different plane spacings and collecting a plurality of spectra. The present invention relates to an automatic qualitative analyzer such as an X-ray microanalyzer.

[0002]

2. Description of the Related Art FIG. 5 is a view schematically showing the construction of an X-ray microanalyzer or the like, wherein 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 spectral crystal, 19 is an X-ray, 20 is a detector, 21 is a mouse,
22, a spectroscope-controlled X-ray measurement unit, 23, a data processing device, 24, a display device, and 25, a keyboard.

[0003] EPMA (X-ray microanalyzer)
Irradiate the sample surface with an electron beam, detect characteristic X-rays generated therefrom, observe the sample surface, analyze the concentration of constituent elements,
It can display a color image of an element distribution state and the like. The structure is as shown in FIG.
1, Wehnelt 12, converging lens 14, objective lens 15
Generates an electron beam 13 narrowed down in a vacuum and irradiates the electron beam 13 on an unknown sample 16 held on a sample stage 17 to obtain a wavelength dispersive X having a plurality of dispersive crystals 18 with different plane spacings
The X-ray spectroscope is scanned, and the characteristic X-rays 19 generated from the unknown sample 16 are detected by the detector 20. A plurality of spectra are collected by the spectroscope-controlled X-ray measurement unit 22, taken into the data processing device 23, and element identification is performed. Processing and so on.

In a conventional automatic qualitative analysis in an X-ray microanalyzer or the like using a wavelength-dispersive X-ray spectrometer, a plurality of data collected by a spectroscope-controlled X-ray measuring unit 22 using a wavelength-dispersive X-ray spectrometer are used. Data processing device 2 for spectrum
3, peaks in the spectrum are detected as proposed in, for example, JP-A-63-58240, and Kα, Kβ, Lα, L
X-rays such as β, Mα, and Mβ are assigned, and the elements present in the sample are identified from the types of the X-rays. More specifically, by obtaining wavelength data of characteristic X-ray data from a plurality of spectral data simultaneously collected using a plurality of X-ray spectrometers, the wavelength data and data of a primary line of each element stored in advance are obtained. And the specific element K,
The presence of the identified element was determined by determining the peak wavelength positions of the α and β rays of L and M.

[0005]

However, according to the above-mentioned conventional method, an element present in a large amount in an unknown sample cannot be obtained.
While the existence can be almost certainly determined, the influence of sub-lines or higher-order lines of these elements sometimes leads to erroneous determination that elements that should not exist at all often exist. Further, since the characteristic X-ray itself used for the determination is either present or absent, there is no criterion for determining how confident the existence of a trace element can be claimed. Was. For this reason, there has been a limit in trying to improve the accuracy of qualitative analysis.

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

[0007]

For this purpose, the present invention provides a method for detecting a characteristic X-ray from a sample by scanning a wavelength dispersive X-ray spectrometer having a plurality of dispersive crystals having different plane spacings, and obtaining a plurality of spectra. An automatic qualitative analyzer such as an X-ray microanalyzer that collects the data, an element identification processing means for detecting the peak of the spectrum and performing element identification processing by qualitative analysis with reference to a table of wavelength, element, and characteristic X-ray; For the peaks of the Kα, Lα or Mα line, Kβ, Lβ or Mβ line of the spectrum which was the basis of the identification of the identified element, and the positive certainty and other positive A confidence calculation means for obtaining a negative certainty factor due to an overlap or contradiction with a higher-order line and for semi-quantitatively obtaining the certainty factor of the existence of the element based on the sum thereof; Those, wherein further comprising a determining means for determining standing.

[0008]

An automatic qualitative analyzer such as an X-ray microanalyzer according to the present invention includes element identification processing means for detecting a peak of a spectrum and performing element identification processing by qualitative analysis with reference to a table of wavelengths, elements and characteristic X-rays. , Kα, Lα or Mα of the spectrum on which the identification of the identified element is based
Line, Kβ, Lβ or Mβ line, and the positive confidence that affirms the presence of the element for the peaks of these higher lines and the negative confidence due to the overlap or inconsistency with other higher lines, Since there are certainty calculating means for semi-quantitatively determining the existence certainty of the presence of the element, and judgment means for judging the presence or absence of the element from the value of the obtained existence certainty, the positive or negative certainty The certainty certainty factor can be calculated semi-quantitatively for each element using the certainty factor, and the presence or absence of the element can be determined based on the certainty factor.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing one embodiment of an automatic qualitative analyzer such as an X-ray microanalyzer according to the present invention, and FIG. 2 is a diagram 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,
Reference numeral 1 denotes a spectrometer-controlled X-ray measurement unit, 2 denotes a spectrum data storage memory, 3 denotes an element identification processing unit, 4 denotes a wavelength table, 5 denotes a certainty calculation unit, 6 denotes a certainty table, and 7 denotes a determination unit.

In FIG. 1, a spectroscope-controlled X-ray measurement unit 1 scans a wavelength-dispersive X-ray spectrometer having a plurality of dispersive crystals with different plane intervals to detect characteristic X-rays from a sample. , And a plurality of spectra are collected, and the spectrum data storage memory 2 stores the plurality of collected spectrum data. The wavelength table 4 stores wavelengths, elements, and characteristic X-ray names.
The element identification processing unit 3 performs peak detection from a plurality of spectra stored in the spectrum data storage memory 2 and performs element identification with reference to the wavelength table 4 for each of those peaks. The confidence table 6 contains the element α,
The certainty that the β-ray exists, the certainty that the secondary line of the element exists, the certainty that overlaps with the X-rays of other elements, the certainty that there exists a contradiction between the X-ray intensities of the elements, and the peak half width It stores information for calculating the uncertainty certainty, and the Kα, Lα or Mα line, Kβ, Kβ, of the spectrum on which the identification of the element identified by the element identification processing unit 3 is based.
For the Lβ or Mβ line and the peaks of these higher-order lines, information on the positive certainty that affirms the existence of the element and negative certainty due to overlap or inconsistency with other higher-order lines is stored. The certainty factor calculation unit 5 calculates the certainty factor of each element identified by the element identification processing unit 3 with reference to the certainty factor table 6 and obtains the total certainty factor (existence certainty factor). The determination unit 7 determines the presence or absence of an element based on the value of the presence certainty calculated by the certainty calculation unit 5.

Next, an element identification flow by the automatic qualitative analyzer having the above configuration 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 in the same manner as in the conventional qualitative identification, and the wavelength table 4 is referred to for each peak. To perform α-ray and β-ray assignment and element identification (steps S1 to S4). If there are n elements identified by this element identification, i =
After setting as 1 (step S5), the α-ray of the i-th element,
Calculate the certainty factor of the existence of the β-ray and the secondary line (step S
6 to S8). Further, a certainty factor that overlaps with the higher-order X-rays of the other identified elements, a certainty factor that there is a contradiction between the X-ray intensities of the i-th element, and a certainty factor that the peak half width is not normal are calculated (step). S9 to S11). Subsequently, the certainty factors obtained in the processes of steps S6 to S11 are summed to determine the existence 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 one to i = i + 1, i is compared with n (steps S13 to S14), and the processing of steps S6 to S12 is repeated until the number of identified elements reaches n.

In performing the above qualitative analysis, a certainty factor for asserting the existence of a certain element from a generally observed spectrum is given as follows. In addition,
Usually, the value of the certainty factor takes a value from 0 to 1, but -100
To 100, and a negative value may be defined as negating the existence value.

The certainty that any α-ray peak of K, L, or M exists. However, which (or both) of K, L and M is taken depends on the atomic number of the element and the accelerating voltage. In general, the peak X-ray intensity is P, and the average background X-ray intensity before and after the peak is B.
Then, the average statistical fluctuation (standard deviation) σ of the net intensity P ₀ = P−B of the X-ray is given by σ = (P−B) / (P + B / 2) ^1/2 . Therefore, if t is defined as P ₀ = σt, the certainty (certainty) that a peak exists is given as a function of t, and the greater the value of t, the higher the certainty that the peak exists. The certainty factor at which the peak exists can be obtained by calculation as a function of t. However, since it takes a long time to calculate, the certainty factor is set to about three to four steps using values of about t = 1, 2, and 3 as a guide. It may be obtained separately, or even if an empirical value is substituted, there is almost no problem in practical use.

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

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

When a K (or L, M) α ray of an element A is present, the line is a K (or L, M, L) of another element B.
M) When overlapping with α-rays or other sub-primary lines or higher-order lines (obstruction lines), the larger the net X-ray of the K (or L, M) α-rays of element B, the larger the element B
Is higher, and conversely, the certainty that element A is present is reduced accordingly. In this case, the degree of reduction depends on the order of higher-order lines of other elements, and when the same order is due to sub-lines other than α-rays, it depends on the relative intensity of those lines 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 line was present but overlapped with other interference lines, it was not detected despite the fact that the Kα (or Lβ) line satisfies the conditions that can be sufficiently detected. If it overlaps with some kind of X-rays of another element and is not detected even though the Lα (or Mβ) ray satisfies the conditions that can be detected, there is a contradiction in the existence of the element itself. Think there is. This increases the confidence that the peak in question is due to another element. Therefore, the certainty factor that is the peak of the element is reduced.

Characteristics X generated from light elements such as Be to F
The half-width of a line is generally observed to be larger than the half-width of characteristic X-rays generated from elements having higher atomic numbers, and higher-order lines of these X-rays often overlap with X-rays of light elements. Therefore, it may be determined that the light element does not actually exist but exists due to higher-order lines of other elements. In order to prevent this, if the magnitude of the half-value width is equal to or less than a certain value, the possibility of the influence of the higher-order line increases, so that the certainty of the existence of the light element is reduced.

By determining the above confidence setting conditions, it is determined whether or not the element in question actually exists. For this purpose, these certainty factors are synthesized. In order to easily perform the synthesis, the above case is calculated as a positive confidence, based on the data such as the detected X-ray intensity, etc. Calculate based on data such as the intensity of major X-rays (α-rays of K, L, and M), the order of the interference, and the relative intensity of other elements that are the source of the interference, and confirm each confidence. What is necessary is just to obtain the sum of the degrees. Also, if it is difficult to calculate the exact confidence value for each element,
A numerical value that can be determined to be appropriate from experience may be used.

Regardless of the method, as long as the value is a certain level of reliability, the existence of the element is ranked A as a certain element by the numerical level classification of the existence of the element by the numerical value of the total value of the certainty factor. By performing a ranking such as B rank as a possible element, it is possible to perform a 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 specific example, a plurality of materials obtained by scanning a wavelength-dispersive X-ray spectrometer having a plurality of dispersive crystals LIF, PET, and TAP from a material containing Fe, Cu, and S (CuFeS2). FIG. 3 shows an example of the spectrum, and FIG. 4 shows the value of each peak obtained by qualitative analysis. As described above, if Fe, Cu, and S are sufficiently contained in the sample, both Fe, Cu, and S have Kα.
The X-ray intensity of the peak of each of the X-ray, Kβ-ray, and Kα secondary line is sufficiently higher than the background X-ray. Then, for Fe, Cu, and S, the positive certainty of becomes sufficiently high, but the negative certainty due to remains at zero. On the other hand, for P, the positive confidence was obtained because the primary line of Kα of P and the quaternary line of Kα of Cu overlapped, but the negative confidence was obtained by As for the certainty factor, the positive and the negative cancel each other and become close to zero. As a result, Fe, Cu and S are present, and the existence of P is denied.

The above example is a simple case. However, even in the case of a delicate element judgment including a large number of trace elements, the accurate judgment result can be obtained because the peak existence certainty is considered as compared with the conventional simple judgment. Can be led.

[0024]

As is apparent from the above description, according to the present invention, the presence of an element is determined based on the certainty (confidence) of the presence of a peak, and therefore, the presence or absence of a conventional peak is determined. A more reliable determination can be made than the binary determination. Further, when the primary line of the Kα (or Kα, Mα) line, which is the basis for the existence of an element, overlaps with another higher-order line, a negative value is given to the certainty of the existence of the element. If there is no other basis for supporting the existence of the element (for example, β-ray or secondary line), 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 for affirming the existence of the element, positive certainty can be obtained by this, and the existence of the element is affirmed. Therefore, a proper judgment can always be obtained. Further, the method of giving the certainty is ideally obtained by a strict calculation. However, even when it is not possible, an empirical numerical value can be used instead. In addition, by using empirical numerical values, it is possible to avoid a case where qualitative identification is often mistaken typically.

[Brief description of the drawings]

FIG. 1 is a diagram showing one 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 and the like.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 23/00-23/227

Claims (1)

(57) [Claims] 1. An automatic X-ray microanalyzer or the like that collects a plurality of spectra by detecting a characteristic X-ray from a sample by scanning a wavelength dispersive X-ray spectrometer having a plurality of dispersive crystals having different plane spacings. A qualitative analyzer, which is an element identification processing means for performing peak identification of a spectrum and performing element identification processing by qualitative analysis with reference to a table of wavelengths, elements and characteristic X-rays, and a basis for identification of identified elements. , Kα, Lα or Mα line, Kβ, Lβ or Mβ line, and the positive confidence in the peaks of these higher-order lines that affirm the presence of the element and the negative due to the overlap or inconsistency of other higher-order lines. And a determination means for determining the presence or absence of an element from the value of the determined existence certainty. Octopus And an automatic qualitative analyzer such as an X-ray microanalyzer.