JPH065296B2 - Peak detection method in X-ray spectrometer - Google Patents

Description

Detailed Description of the Invention a. TECHNICAL FIELD The present invention relates to a peak detection method in a wavelength dispersive X-ray spectrometer.

B. 2. Description of the Related Art In a wavelength dispersive X-ray spectroscope used for an X-ray microanalyzer, etc., when the position of a spectral peak is determined using a computer, an intensity comparison method or a smoothing method considering statistical fluctuations of the X-ray detection signal Is used to determine the maximum intensity position of the X-ray and set as the peak position.

C. Problems to be Solved by the Invention In the above-described conventional peak position determination method, the peak position may be erroneously determined if there is continuous noise. The present invention provides a method capable of reliably determining the peak position by removing the influence of continuous noise even if the noise is mixed.

D. Means for Solving Problems In addition to an appropriate peak position determination method, the position-determined peaks are verified to increase the accuracy of peak position determination. The means for verifying the peak whose peak position has been determined has the half-value width of the peak of the X-ray spectrum determined in advance as a characteristic of the X-ray spectroscope. The true peak is obtained when the half-width measured by comparison with the half-width is equal to or wider than the predetermined half-width.

E. Operation The minimum half value width of the park of the X-ray spectrum obtained by the wavelength dispersive X-ray spectroscope is determined by the resolution of the X-ray spectroscope and is known data for the X-ray spectroscope. The full width at half maximum of the peak of the actual X-ray spectrum is somewhat wider than the minimum full width at half maximum due to the intensity of the peak. Therefore, it is judged that the narrow peak is not a true peak but noise is picked up from this minimum half width. If a peak is detected by an appropriate peak detection method (including a conventional method) and the above-mentioned verification means is added to it, the accuracy that the detected peak is a true peak is significantly improved.

F. Example FIG. 1 is a diagram for explaining an example of the method of the present invention. The method shown in this figure is a method that is executed after the wavelength scanning of the X-ray spectroscope is performed and the X-ray intensity data is loaded into the memory. Smoothing processing is performed on the captured X-ray intensity data, and a peak is detected by an appropriate means such as a maximum value detection means. FIG. 1 shows one peak thus detected. If the maximum value of this peak is Ia and the baseline level is Ib, And the half width of the peak, that is, the peak width Δλw at (Ia + Ib) / 2, and the wavelength λ corresponding to the peak maximum value.
When Δλw> Δλp, where Δλp is the minimum half-width of the X-ray spectroscope at p, the peak shown is a true peak.
Δ in the equation (1) is a number expressing the certainty. When δ = 1, the certainty is 68.3% δ = 2, and 95.4% δ = 3, and 99.7%.

FIG. 2 is a diagram for explaining a case where peak detection is performed while performing wavelength scanning with an X-ray spectroscope. The wavelength scanning proceeded to the wavelength λl, and the maximum intensity Ia was detected at λk.
Here, in the same way as the above formula (1), And for the minimum half-width Δλp at λl,
When the measured half width Δλk is Δλk> Δλp, λk is the peak position of the true peak.

FIG. 3 shows an example of a device configuration for implementing the present invention. e is an electron beam, S is a sample, M is an X-ray spectroscope, and D is an X-ray detector. 1 is an X-ray spectroscope driving device, which is a computer CP
It is controlled by U. Reference numeral 2 indicates the wavelength and intensity of the X-ray peak detected by the display device. 3 is a memory. The CPU stores a table of minimum full width at half maximum at each wavelength value of the X-ray spectrometer.

FIG. 4 is a flowchart of the peak detecting operation described in FIG. A certain wavelength range is set around one peak wavelength of the element to be detected, the wavelength of the X-ray spectroscope is advanced by one step (a), and the X-ray intensity Io is sampled (b), Is calculated (C), and In is stored in the memory together with the wavelength of Io (D). In is 1/2 the X-ray intensity this time, 1/4 the previous X-ray intensity, 1/8 the previous X-ray intensity, and n.
Weighted average of weighting (1/2) ⁿ to the previous X-ray intensity and adding, 11, 12, ... In are smoothed X-ray intensity data, which are accumulated in the memory. Step Following (d) in step (e) to determine whether _{I n -I n-1 ≦ 0} , returns to the operation if the determination is NO (i), reads the data from the YES if the memory until it, the minimum The peak determination (f) described in FIG. 2 is performed using the half-width data. Judgment result If it is not a true peak (ii)
Return to, if it is a true peak, wavelength λk corresponding to In
And the peak intensity In are output to the display device (G), the operation returns to (A), the scanning in the set wavelength range is completed, and the one element detection operation is completed.

G. Effect According to the present invention, the accuracy of peak detection is improved because the confirmation by the half width is added to the conventional peak determination. In the case of X-ray spectroscopic analysis, if Kβ ray is detected together with the Kα ray for one element, one detected peak is K for that element.
Although it can be confirmed as an α ray, if this is done, the range of wavelength scanning becomes wide and analysis takes time. According to the present invention, the analysis time can be shortened because the peak can be reliably determined even with a single peak.

[Brief description of drawings]

FIG. 1 is a graph for explaining an embodiment of the present invention, FIG. 2 is a graph for explaining another embodiment, FIG. 3 is a block diagram showing the constitution of an example of an apparatus for carrying out the method of the present invention, and FIG. The figure is a flow chart of the operation of performing the method described in FIG. 2 in the apparatus of FIG.

Claims (1)

[Claims] 1. A correspondence table of wavelengths of an X-ray spectroscope and minimum full width at half maximum is stored, and when an X-ray peak is detected by an appropriate method, the full width at half maximum of the peak and the center wavelength thereof are converted from the above table. A peak detection method in an X-ray spectroscope, characterized in that the detected peak is determined to be a true peak when the former is larger than the latter by comparing the read minimum half-width.