JPH0792443B2 - Quantitative analysis method by X-ray spectroscopy - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a quantitative analysis method in X-ray spectroscopic analysis in which a sample is excited by an electron beam to disperse X-rays emitted from the sample.

(Prior Art) In quantitative analysis by X-ray spectroscopy, the X-ray intensity of each component element in a sample is affected by other coexisting elements, so correct quantification is required without correction for the effect of other coexisting elements. I can't get the value. This correction is usually performed for three items, and these items are collectively called ZAF correction for atomic number correction, absorption correction, and fluorescence correction.

The concentrations of coexisting elements need to be known to perform ZAF correction, but the concentrations of each component element are unknown during analysis. Therefore, first, the primary approximate concentration of each element is obtained by simple calculation from the ratio of the characteristic X-ray intensity of the constituent element in the X-ray spectrum emitted from the sample and the characteristic X-ray intensity of the pure sample of each element, and used. ZAF correction is performed to calculate the second-order approximate concentration of each element, and the ZAF correction is performed again using it to obtain the correct concentration of each component by the convergent value of each element concentration by the successive approximation method. .

However, the accuracy of the above-mentioned ZAF correction calculation and the dependence of the error due to the surface condition due to the sample pretreatment method on the acceleration voltage of the sample-excited electron beam vary from element to element. Are different. However, in the past, since the same electron beam accelerating voltage was used for all elements for one sample, it was difficult to improve the accuracy of analysis, and in some cases ZAF correction may converge to a value different from the actual value. However, the reliability was not sufficient, and this difficulty was greater as the atomic number difference between the constituent elements contained in the sample was larger.

(Problems to be Solved by the Invention) The present invention is intended to improve reliability and analysis accuracy in X-ray spectroscopic quantitative analysis for ZAF correction.

(Means for Solving the Problem) In the quantitative analysis by X-ray spectroscopy, the acceleration voltage of the electron beam for excitation is set to the optimum value for each component element, and the primary approximate concentration of each component element is determined, Using the above acceleration voltage data
Added ZAF correction calculation.

(Operation) In the ZAF correction calculation, the minimum excitation electron beam acceleration voltage Ec of the element and the actual excitation electron beam acceleration voltage Eo are included as calculation elements. Conventionally, the above-mentioned actual excited electron beam acceleration voltage Eo has a single value for each component element in common for one sample. In the present invention, this Eo is set to the optimum value for each component element. The minimum excitation line accelerating voltage is a constant that is predetermined by the element. The X-ray intensity is measured at each optimum excitation line acceleration voltage for each component and is also used in the ZAF correction calculation, so the ZAF correction calculation always converges to the actual concentration value, providing a highly reliable and accurate analysis. The result is obtained.

(Embodiment) FIG. 1 is a flow chart showing the procedure of an analysis operation according to the present invention. For the sample component elements A, B, C, etc., the optimum accelerating voltage Eao, Ebo, etc. for each excitation electron beam and the minimum accelerating voltage Eac,
Input Ebc, etc. to the control device. When the EPMA is started, the control device switches the electron beam accelerating voltage to Eao, Ebo, ... In order according to the above setting data, while at the accelerating voltage Eao, the characteristic X-ray intensity Ia of the element A and at the accelerating voltage Ebo, the characteristic of the element B. As with the X-ray intensity Ib, the characteristic X-ray intensity I at each optimum accelerating voltage is measured for each element and the value is taken in (b). After the above measurement is completed for all elements of the sample components, ZAF correction calculation is started using Eo, Ec, I (supplementary items a, b, c ...) of each element. First, the first-order approximate concentrations Ca1, Cb1, ... etc. of each element are obtained from the ratio of the special X-ray intensities of the pure samples of each element and each I (C), and this and Eo, Ec etc. of each element are obtained. Using the primary ZAF correction factors Ca1, Cb1,… of each element
Etc. are calculated (d), the second-order approximation concentrations Ca2, Cb2, etc. are calculated from Ia × Ca1, Ib × Cb1, ... (e), and the ZAF correction coefficient is calculated again using this second-order approximation concentration ( ) Then, similarly, when the difference between the previously calculated concentration and the currently calculated concentration falls below the predetermined value, the final calculated concentration value of each component is set as the target quantitative value, assuming that the ZAF correction has converged.

In ZAF correction calculation, for example, in absorption correction, With atomic number correction The values of Eo and Ec come in for each element in the form of etc. Data such as σ and S described above for all component elements are included in the ZAF correction coefficient of each component element, and Eac, Ebo, etc. described above are used for each element data.

(Effect) According to the present invention, the characteristic X-ray intensity is measured for each element by using the optimum accelerating voltage of the excited electron beam, and ZAF is measured by using the accelerating voltage.
Since the correction calculation is performed, the correction calculation is highly reliable and accurate analysis results can be obtained.

[Brief description of drawings]

The drawing is a flow chart showing the operation procedure of an embodiment of the present invention.

Claims (1)

[Claims] 1. When a sample is excited by an electron beam, X-rays emitted from the sample are dispersed, and a ZAF correction operation is performed to quantify the constituent element, the optimum excited electron for that element is calculated for each constituent element. According to the X-ray spectroscopy, the characteristic X-ray intensity of the element is measured using the linear acceleration voltage, and the optimum acceleration voltage described above is used as electron beam acceleration voltage data for each element in the ZAF correction calculation. Quantitative analysis method.