JPH03148089A - Detector of total-reflection fluorescence x-ray analyzing apparatus - Google Patents

Abstract

PURPOSE:To omit a collimator and to improve sensitivity by forming a material constituting a detector within a range wherein scattering X rays are projected and fluorescence X rays are generated with the same element as a target material of an X-ray tube which projects primary X rays into a sample. CONSTITUTION:An X-ray tube 1, a cathode filament 2, a cap 4, an electrode 9 and the like are formed of molybdenum. A detector 11 is also formed of molybdenum like a target material 3 of the X-ray tube 1. Primary X rays 13 which are emitted from the X-ray tube 1 are inputted into a sample 12 at a total reflection angle, and scattering X rays generated from the sample 12 are inputted into the cap 4. Even if the scattering X rays excite the cap 4 and the electrode 9 and fluorescence X rays are generated, the fluorescence X rays become the same kind as the primary X rays. Therefore, the spectrum of the fluorescence X rays which are generated by the excitation of an element to be measured and the spectrum of the fluorescence X rays which are generated by the excitation from the cap 4 and the electrode 9 have the almost different wavelength regions. Thus the effect on the measurement of the element to be measured becomes almost negligible, and the use of a collimator is omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a detector for a total internal reflection fluorescent X-ray analyzer used to measure elements on the surface of a sample.

(Prior Art) As a total internal reflection fluorescent X-ray analyzer used to measure elements on the surface of a sample, for example, the one shown in FIG. 2 is known.

In FIG. 2, 21 is an X-ray tube, and the target material 23 facing the cathode filament 22 is molybdenum (MO
). The primary X-ray 24 emitted from the xm tube 21 passes through the slits 25a and 25b, becomes a narrow beam, and enters the sample 27 attached to the sample attachment part 26 at a total reflection angle, most of which is reflected. be done. Two scintillation counters monitor the primary X-rays 24 reflected by the sample 27 through a slit 28.

On the other hand, the element to be measured on or near the surface of the sample 27 is excited by the irradiation with the primary X11A24 and becomes fluorescent X11A24.
The fluorescent X-rays are incident on the detector 30, which detects the spectrum and outputs a signal. The signal output from this detector 30 is transmitted to the preamplifier 3
1. The signals are sequentially sent to the linear amplifier 32 and A/D converter 33, where they are converted and amplified, and digitally converted. Displays the energy spectrum of fluorescent X-rays.

The computer 34 also sends a signal to the sample position control circuit 35 to operate the sample mounting section 26 and
The primary Xl incident on ! control the total reflection angle and others.

The detector 30 is constructed as shown in FIG.

In FIG. 3, numeral 37 is a cylindrical cap made of stainless steel, and an opening 39 formed in an end wall 38 of the cap is closed with a window 40 made of beryllium.

41 is an S disposed within the cap 37 facing the window 40;
L (Li) detection element, 42 is an electrode provided in contact with the detection element 41, 43 is a holder for electron fli 42, and 44 is a collimator attached to the cap 37 facing the window 40. Since the other parts are the same as those in FIG. 2, they are indicated by the same reference numerals.

That is, as described above, when the primary X-rays 24 are incident on the sample 27 at a total reflection angle, elements on or near the surface of the sample 27 are excited by the primary X-rays 24 and emit fluorescent X-rays. Generate a line. This fluorescent X-ray passes through the collimator 44 and the window 40 and enters the detection element 41, and the detection element 41 detects its spectrum.

Without the collimator 44, the primary X-rays 24 would be incident on the sample 27 and generated from the sample 27, or scattered X-rays would be scattered in the air and enter the cap 37;
Since the cap 37, the electrode 42, and other components of the detector 30 are excited to generate unnecessary fluorescent X-rays, the unnecessary fluorescent X-rays are incident on the detection element 41, and the spectrum of the unnecessary fluorescent X-rays is changed. Also detected.

Moreover, since the cap 37, the electrode 42, and other elements constituting the detector 30 often match the elements to be measured such as the surface of the sample 27, the wavelength range of the spectrum of fluorescent X-rays generated from the element to be measured is There is a greater possibility that the wavelength ranges of the spectra of the unnecessary fluorescent X-rays overlap, and problems such as the unnecessary fluorescent X-rays lowering the measurement accuracy of the element to be measured occur.

Therefore, in order to prevent the generation of unnecessary fluorescent X-rays,
Scattered Xf generated from sample 27 or scattered in the air
m enters the cap 37, the collimator 44
It is prevented by

(Problems to be Solved by the Invention) As described above, the conventional detector 30 is equipped with a collimator in the cap 37 in order to prevent scattered X-rays generated from the sample 27 etc. from entering the carrier jib 37. 44, the incident angle of the fluorescence Xl1l generated from the element to be measured such as the surface of the sample 27 becomes small. Therefore, the amount of fluorescence xsl incident on the detection element 41 decreases, resulting in lower sensitivity and poor S/N ratio.

Further, when the element to be measured is in a trace amount, the amount of fluorescent X-rays generated from it is small and detection by the detection element 41 becomes difficult, so there is also the problem that it is difficult to measure the vl amount element.

The present invention solves the above-mentioned problems, and
Even if the elements constituting the detector are excited by scattered X-rays and generate fluorescent X-rays, this does not affect the measurement of the fluorescent X-rays generated from the element to be measured, eliminating the need to use the collimator. The object of the present invention is to scale the detector of a total internal reflection fluorescent X-ray spectrometer. In the detector, in which a detection element for detecting the fluorescent X@ transmitted through the window is arranged and a pole is provided in contact with the detection element, the sample is irradiated with scattered X-rays generated by the incidence of the primary X-rays. Fluorescent X#! The present invention is characterized in that the detector constituent material in the range where 1 is generated is made of the same element as the target material of the X-ray tube through which the primary X-rays are incident on the sample.

As the target material of the X-ray tube, for example, molybdenum (Mo)t or tungsten (W) is used, and constituent materials such as the cap and electrodes of the detector are formed using these materials.

(Function) In this detector, the detector components in the range where fluorescent X-rays are generated due to the irradiation of scattered X-rays generated when the primary X-rays are incident on the sample, cause the primary X-rays to be incident on the sample. It is made of the same elements as the material used in X-ray tubes. Therefore, even if the scattered X-rays generated when the primary X-rays are incident on the sample at a total internal reflection angle pass through the window and enter the cap, exciting parts of the cap or electrodes and generating fluorescence Xi, This fluorescent X-ray is of the same type as the primary X-ray, and it has almost no effect on the spectrum measurement of the fluorescent X-ray of the element to be measured.
As a result, there is no need to use the collimator of the conventional detector.

(Example) An example of the detector of the total internal reflection fluorescent X-ray analyzer of the present invention will be described with reference to FIG.

In FIG. 1, 1 is an X-ray tube, and a target material 3 facing a cathode filament 2 is made of MO.

4 is a cylindrical cap made of MO, and its end wall 5
An opening 6 provided in the opening 6 is closed with a window 7 made of beryllium. Reference numeral 8 denotes a 5t (Li) detection element disposed in the cap 4 facing the window 7, and 9 an electrode provided in contact with the detection element 8, which is also made of Mo. 10 is a holder for the electrode 9; 11 is a detector configured as described above;
12 is the sample, 13 is 1 which is incident on the sample 11 at the total reflection angle.
Next xi.

As described above, in this detector 11, the cap 4 and the electrode 9 facing the sample 12 are made of the same MO as the target material 3 of the X-ray tube 1. Therefore, the primary X-rays 13 emitted from the X-ray tube 1 are incident on the sample 12 at a total reflection angle, and the scattered X-rays generated from the sample 12 etc. are incident on the cap 4. Even if fluorescent X-rays are generated by exciting the electron #19, these fluorescent X-rays are of the same type as the primary X-rays.

Therefore, the fluorescence X generated when the element to be measured is excited
The wavelength range of the spectrum of the rays and the spectrum of the fluorescent X-rays generated by excitation of the cap 4 and electrode 9 are almost different, so the fluorescent There will be almost no impact on it. As a result, there is no need to use the collimator of the conventional detector.

Note that whether the entire cap 4 is made of Mo or the window 7 is
Portions of the cap 4 that are far away from the object and are not likely to be exposed to scattered X-rays may be made of a material other than MO, such as stainless steel, for example. And electric tif
The holder 10 of No. 19 may be made of a material other than MO, or the holder 10 may also be made of Mo. Although not shown in the drawings, if the cap 4 or the electrode 9 uses, for example, machine screws or other parts, and there is a risk that they may be irradiated with scattered X-rays, these parts are also classified as M.

It is formed by

(Effects of the Invention) As described above, the detector of the total internal reflection fluorescence X-ray analyzer of the present invention is capable of detecting the irradiation of the primary X-rays incident on the sample at the total reflection angle and the irradiation of the scattered X-rays generated from the sample. Since the components of the detector such as the cap and electrode in the area where fluorescent X-rays are generated are made of the same element as the target material of the X-ray tube that injects the primary X-rays into the sample, the scattered X-rays are When fluorescent X-rays are generated from the detector component upon irradiation, the fluorescent X-rays are of the same type as the primary X-rays.

Therefore, the wavelength range of the energy spectrum of fluorescent X-rays generated when the element to be measured on or near the surface of the sample is excited, and the spectrum of the fluorescent X-rays generated when the detector component is excited. It is almost different from the wavelength range of ~le. Therefore, when fluorescent X-rays generated from the element to be measured are input and the detector detects its energy spectrum, the spectrum of the fluorescent X-rays generated from the detector's constituent materials is different from that energy spectrum. Since there is almost no influence and the element to be measured can be measured with high precision, it is not necessary to provide the collimator of the conventional example.

In this way, there is no need to use a collimator, and the angle of incidence of the fluorescent X-rays generated by the excitation of the element to be measured on the detector is increased, so sensitivity is improved and trace elements can be detected. Furthermore, since the background with respect to the energy spectrum of the fluorescent X-ray of the element to be measured is reduced, the S/N is further reduced to 0, and the detectable limit is improved.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of essential parts of an embodiment of the present invention, Fig. 2 is a block diagram of a conventional total internal reflection fluorescent X-ray analyzer, and Fig.
FIG. 2 is a sectional view of a main part of the detector of the device shown in FIG. X-ray tube, 3: target material, 4: cap, 7: window,
8: detection element, 9: electrode, 13: primary X-ray.

Claims (1)

[Claims] A detection element for detecting fluorescent X-rays transmitted through the window is placed inside the cap, and in the detector of the total internal reflection fluorescence X-ray analyzer, which has an electrode in contact with this detection element, primary X-rays are applied to the sample. The detector component material in the range where fluorescent X-rays are generated by the irradiation of scattered X-rays generated by the incidence of the sample is made of the same element as the target material of the X-ray tube that injects the primary X-rays into the sample. Detector of total internal reflection fluorescent X-ray analyzer.