JPH075128A - X-ray fluorescence analytic equipment - Google Patents

Abstract

PURPOSE:To obtain a correct quantitative value even upon fluctuation in the profile of spectral shape by arranging a plurality of fixed wavelength X-ray spectrometers having detection wavelength shift for one element and calculating the spectral profile of characteristic X-ray of the element based on the output values from the spectrometers. CONSTITUTION:Three X-ray spectrometers 3, for example, are arranged radially around a sample 1 for one element to be analyzed. One spectrometer is set to detect the standard wavelength of characteristic X-rays of a target element and the other spectrometers are shifted by a known wavelength, respectively, to the long wave side and the short wave side. Counters 11 count the outputs from an X-ray detector 7 and a data processor 12 takes in the counts for a predetermined time. The data processor 12 calculates the features, e.g. the peak of characteristic X-rays, the center of peak, and the intensity integrated for the wavelength, for each element to be determined from three data for one element. Since the peak profile is determined in such a manner, correct quantitative results can be obtained even upon fluctuation in the spectral profile.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for quantitatively analyzing a sample by fluorescent X-ray.

[0002]

2. Description of the Related Art To perform a fluorescent X-ray analysis, the spectrum data of fluorescent X-rays emitted from a sample is collected by an analyzer using a wavelength scanning X-ray spectroscope to qualitatively and quantitatively analyze sample components. There is also a way to do it, but it also takes time to analyze, so
In some cases, a fixed wavelength X-ray spectroscope uses a non-scanning type analyzer in which the detection wavelength is adjusted to the wavelength of the characteristic X-ray of the element for quantitative determination.

[0003]

The present invention relates to the latter of the above-mentioned devices, but in a device using a fixed wavelength type spectroscope, one spectroscope is used for each characteristic X-ray of one element. Since there is no data of the profile of the characteristic X-ray peak, the intensity of the detected characteristic X-ray changes even if the peak position is slightly deviated.
On the other hand, some of the components in the sample are ultra-light elements such as N and C, and the change in the shape of the characteristic X-ray spectrum due to the binding state in the sample may not be neglected. In the method using the wavelength type X-ray spectroscope, the change in the intensity of the characteristic X-ray due to the change in the shape of the spectrum is mistakenly recognized as the difference in the concentration of the element. The present invention intends to provide a fluorescent X-ray analyzer capable of obtaining a correct quantitative value without using such a change in the shape of the characteristic X-ray spectrum while using a fixed wavelength X-ray spectrometer. Is.

[0004]

A plurality of fixed wavelength type X-ray spectroscopes are arranged around a sample for one element to be analyzed, and the detection wavelengths of those X-ray spectroscopes are set to the above-mentioned elements. The characteristic X-ray spectrum of the above-mentioned element radiated from the sample is calculated from the output values of these plural X-ray spectroscopes, including the one characteristic X-ray wavelength of the The target element was quantified by the height or area of the peak top of the profile.

[0005]

[Function] Since one characteristic X-ray peak of one element is detected by a plurality of X-ray spectroscopes having slightly different detection wavelengths, one spectrum is measured at a plurality of points. Therefore, the peak profile can be obtained. Therefore, even if the peak position is slightly deviated, a correct value for the peak height or area can be obtained.

[0006]

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a sample, and 2 above it is an X-ray source for exciting the sample. Three
Is a fixed-wavelength type X-ray spectroscope, and two are shown on the left and right in the figure. Three spectroscopes are arranged around the sample for each element to be analyzed, and the arrangement is seen from above. , It is radial around the sample.

FIG. 2 shows one of the above-mentioned X-ray spectroscopes 3, wherein 4 is an entrance slit, 5 is a dispersive crystal, 6 is an exit slit, and 7 is an X-ray detector. The entrance slit 4 is fixed to the frame 8 of the spectroscope, but the exit slit 6 is movable along a guide 9 in the direction of the cutting line of one Rowland circle C passing through the entrance slit and the center of the dispersive crystal 5, and a fine adjustment screw is used. The position can be adjusted in the cutting line direction of the Rowland circle C by 10. The above three sets of X-ray spectroscopes for one element have X of standard wavelength (wavelength when peak is not shifted) of the characteristic X-ray of the target element when the exit slit 6 is adjusted to the reference position. The respective positions with respect to the center of the dispersive crystal 5 are set so that the lines are detected. For one element, one of these three spectroscopes is set to detect the standard wavelength of the characteristic X-ray of the target element, and the other two are set on the long wavelength side with respect to this standard wavelength. The exit slit 6 is displaced from the reference position by the known wavelength on the short wavelength side. There are three X-ray spectrometers arranged in this way for one element. However, X for each element
The number of line spectroscopes is not limited to three.

As shown in FIG. 1, the output of the X-ray detector 7 of each X-ray spectroscope is counted by the counter 11, and the count value for a certain period of time is fetched by the data processor 12. The data processor collects three data for each element. The data processing device calculates characteristics such as the peak height and the peak center of the characteristic X-ray of each element to be quantified from the data of the three elements and the intensity integrated with respect to the wavelength. Fig. 3 shows the results of quantifying nitrogen in three kinds of nitrogen compounds with this device. O on the horizontal axis is the standard wavelength position of the characteristic X-ray wave of N, and A and B on both sides are three wavelengths. The detection wavelength positions of the other two of the X-ray spectroscopes are shown. Triangle marks are the measurement results of BN, white circles are the measurement results of NaNO ₃ , and black circles are (NH
₄ ) Measurement result of ₂ SO ₄ . The data processing device determines three coefficients from the three measurement data, using the peak shape as a quadratic equation, and obtains the maximum value and its position in FIG. 3 for the determined peak shape. To obtain the peak shape, an error function may be used instead of the quadratic equation to determine the three constants in Kexp (−ax ² ) + C. FIG. 3 shows the peak profile of each sample thus determined.

As is clear from the results shown in FIG. 3, even in the same determination of nitrogen, the peak center is deviated from the standard position depending on the type of compound, and when this is measured at only one point in the center, However, the amount of nitrogen is underestimated, and in the case of the example in FIG. 3, the influence is particularly large in the case of NaNO ₃ .

[0010]

According to the present invention, since a peak profile is determined by simultaneously measuring three X-ray spectra at three positions in each of the above examples, a correct quantitative result can be obtained even if the shape of the spectrum changes. It can be obtained, and the time required for analysis is shortened because wavelength scanning is not performed. Shortening the analysis time not only improves the analysis efficiency, but also in the case of a sample that is altered when it is irradiated with excited X-rays for a long time,
Since it could not be analyzed by the wavelength scanning method, it also leads to the expansion of the applicable range of the fluorescent X-ray analysis method.

[Brief description of drawings]

FIG. 1 is a side view of an apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of the X-ray spectroscope used in the above embodiment.

FIG. 3 is a graph of an example of analysis by the device of the present invention.

[Explanation of symbols]

 1 sample 2 sample excitation X-ray source 3 X-ray spectroscope 4 entrance slit 5 dispersive crystal 6 exit slit 7 X-ray detector 8 frame 9 guide 10 adjusting screw 11 counter 12 data processing device

Claims (1)

[Claims] 1. A plurality of fixed wavelength X-ray spectroscopes having different set wavelengths for each characteristic X-ray to be measured from the fluorescent X-rays emitted from the sample are arranged around the sample. In addition to the arrangement, a data processing device for determining the peak profile of the characteristic X-ray to be measured from the output of each X-ray spectroscope and determining the height of the peak center, the peak area, etc. is provided. X-ray fluorescence analyzer.