JP3266896B2 - X-ray fluorescence 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 apparatus for quantitatively analyzing a sample by X-ray fluorescence.

[0002]

2. Description of the Related Art To perform X-ray fluorescence analysis, spectral data of X-ray fluorescence emitted from a sample is collected by an analyzer using a wavelength-scanning X-ray spectrometer to determine the qualitative and quantitative determination of sample components. There are ways to do this, but the analysis will take a long time,
In some cases, a non-scanning analyzer that uses a fixed-wavelength X-ray spectrometer to adjust the detection wavelength to the characteristic X-ray wavelength of the element to be quantified is used.

[0003]

SUMMARY OF THE INVENTION The present invention relates to the latter one of the above-mentioned devices. In an apparatus using a fixed wavelength type spectroscope, one spectrometer is used for one characteristic X-ray of one element. , There is no data of the profile of the characteristic X-ray peak, and even if the peak position is slightly shifted, the intensity of the detected characteristic X-ray changes.
On the other hand, some of the components in the sample may not be able to ignore changes in the shape of the characteristic X-ray spectrum caused by the bonding state in the sample with ultra-light elements such as N and C. In a method using a wavelength type X-ray spectroscope, a change in the intensity of characteristic X-rays due to a change in the shape of the spectrum is mistaken for a difference in the concentration of the element. An object of the present invention is to provide a fluorescent X-ray analyzer capable of obtaining a correct quantitative value without being affected by such a change in the shape of the characteristic X-ray spectrum while using a fixed wavelength X-ray spectrometer. It is.

[0004]

A plurality of fixed-wavelength X-ray spectrometers are arranged around a sample for one element to be analyzed, and the detection wavelength of the X-ray spectrometer is set to the above-mentioned element. One of the characteristic X-ray wavelengths is set to be slightly different from each other in the vicinity of the characteristic X-ray wavelength, and the characteristic X-ray spectrum profile of the above element radiated from the sample is calculated from the output values of the plurality of X-ray spectrometers. The target element is quantified based on the height of the peak top and / or the area of the profile or both .

[0005]

[Function] Since one characteristic X-ray peak of one element is detected by a plurality of X-ray spectrometers having slightly different detection wavelengths, one spectrum is measured at a plurality of points. That is, a peak profile can be obtained. Therefore, even if the peak position is slightly shifted, a correct value of the peak height or the area is 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 sample excitation. 3
Is a fixed-wavelength X-ray spectrometer, two of which are shown on the left and right in the figure, but three spectrometers are arranged around the sample for each element to be analyzed. , Radially around the sample.

FIG. 2 shows one of the above-mentioned X-ray spectrometers 3, wherein 4 is an entrance slit, 5 is a spectral 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, while the exit slit 6 is movable along the guide 9 in the direction of the incision of one Rowland circle C passing through the entrance slit and the center of the dispersive crystal 5. 10, the position can be adjusted in the cutting line direction of the Rowland circle C. When the exit slit 6 is adjusted to the reference position, the set of three X-ray spectrometers described above for each element has a standard wavelength (wavelength when the peak is not shifted) of the characteristic X-ray of the target element. Each position with respect to the center of the dispersive crystal 5 is set so that a line is detected. For one element, one of the three spectrometers is set to detect the standard wavelength of the characteristic X-ray of the target element, and the other two are set to the longer wavelength side with respect to this standard wavelength. The exit slit 6 is shifted from the reference position by a known wavelength on the shorter wavelength side. Three X-ray spectrometers thus adjusted for one element are arranged. X for each element
The number of line spectrometers is not limited to three.

As shown in FIG. 1, the outputs of the X-ray detectors 7 of the respective X-ray spectrometers are respectively counted by a counter 11, and a count value for a certain time is taken into a data processing device 12. The data processing device captures three data for each element. The data processing device calculates characteristics such as the peak height, the center of the characteristic X-ray, and the intensity integrated with respect to the wavelength of the characteristic X-ray of each element to be quantified from the three data of one element. FIG. 3 shows the results of the determination of nitrogen in three types of nitrogen compounds by this apparatus. 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 thereof are three. The triangular marks indicate the measurement results of BN, the white circles indicate the measurement results of NaNO ₃ , and the black circles indicate (NH).
₄ ) Measurement results of ₂ SO ₄ . The data processing device determines three coefficients from the three measurement data using the shape of the peak as a quadratic expression, and obtains the maximum value and its position on FIG. 3 for the determined shape of the peak. The shape of the peak may be determined not by a quadratic equation but by using an error function to determine three constants in Kexp (−ax ² ) + C. FIG. 3 shows the peak profile of each sample thus determined.

As is apparent from the results of FIG. 3, even in the same quantification of nitrogen, the peak center is shifted from the standard position depending on the kind of the compound. , The amount of nitrogen is underestimated. In the case of the example of FIG. 3, the effect is particularly large in the case of NaNO ₃ .

[0010]

According to the present invention, the peak profile is determined by simultaneously measuring a plurality of locations in one of the X-ray spectra at three locations in the above example, so that a correct quantitative result can be obtained even if the shape of the spectrum changes. Since no wavelength scanning is performed, the time required for analysis is reduced. The shortening of the analysis time is not only an improvement of the analysis efficiency, but also the case of a sample that changes its quality when exposed to the excitation X-ray for a long time.
Since analysis could not be performed by the wavelength scanning method, the range of application of the fluorescent X-ray analysis method can be expanded.

[Brief description of the 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 spectrometer used in the embodiment.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sample 2 X-ray source for sample excitation 3 X-ray spectrometer 4 Inlet slit 5 Dispersion crystal 6 Outlet slit 7 X-ray detector 8 Frame 9 Guide 10 Adjustment screw 11 Counter 12 Data processing device

Claims (1)

(57) [Claims] 1. A plurality of fixed-wavelength X-ray spectrometers having different setting wavelengths for each characteristic X-ray to be measured are arranged around a sample from fluorescent X-rays emitted from the sample. And a data processor for determining the peak profile of the characteristic X-ray to be measured from the output of each of the X-ray spectrometers and obtaining the height of the peak center or the peak area or both. X-ray fluorescence spectrometer.