JPH0330101B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a constant periodicity to spectral wavelengths by applying minute rotational vibrations to an X-ray spectroscopy crystal, which has conventionally been used to extract only a specific wavelength and its integral multiple wavelength. The present invention relates to an X-ray measurement method in which X-ray diffraction, scattering, absorption, etc. can be measured with high accuracy by modulating the X-rays using a phase-sensitive detection method.

In general, the principle of spectroscopy that utilizes the Bragg reflection of crystals is based on selecting a specific wavelength and its integral multiples that satisfy the following equation (1) from among continuous wavelength (white) X-rays.

2d _ok1・sinθ _p = nλ ……(1) Here, θ _p : Bragg angle of hk1 reflection d _ok1 : Interplanar spacing of hk1 plane λ : Wavelength of X-ray due to primary reflection Here, the spectroscopic crystal is further divided into minute δθ The wavelength change can be approximately expressed by the following equation (2).

Δλ〜2d _hk1 cosθ _p sinδθ ...(2) (using the fact that δθ≪1) If δθ is moved sinusoidally at each frequency ω, the wavelength change based on δθ is from δθ≪1, Part below
It can be expressed by equation (3).

Δλ~2d _hk1 Asin(ωt+α) (3) where A: amplitude of δθ α: phase of δθ Equation (3) shows that the wavelength change Δλ can be expressed by a sine function.

This invention has been made based on the above principle. Hereinafter, this invention will be explained using the drawings.

FIG. 1 shows a spectroscopic crystal section in one embodiment of the present invention. In this figure, 1 is an X-ray source,
Reference numerals 2 and 2' designate spectroscopic crystals, which are mounted on the rotary table 3, and the distance between the spectroscopic crystals 2 and 2' is D.
Both crystals 2 and 2' constitute a spectroscopic system, and by rotating the spectroscopic crystals 2 and 2' around the incident point of parallel X-rays from the X-ray source 1, the equation (1) Only X-rays with wavelengths that satisfy (generally nλ, n=
1, 2, ..., but for the sake of simplicity, higher-order terms will be ignored here), and are reflected in parallel to the incident light. If a minute rotation is applied by a minute angle δθ near a certain Bragg angle θ _p , the spectroscopic crystal 2 will tilt from OA to OA', and the reflected X-ray path will change from OP to OP'.

At this time, an X-ray having a wavelength λ' (=λ+Δλ) that has undergone wavelength modulation expressed by equation (2) can be extracted in parallel to the incident X-ray. By synchronizing the phase of the detection system with this wavelength modulation, modulated X-ray spectrometry and modulated X-ray diffraction become possible.

The above is the principle of the present invention, and an example of an apparatus for carrying out the X-ray measurement method of the present invention using the principle is shown in the block diagram of FIG.

In FIG. 2, 11 is an X-ray source, 12 is a spectroscopic crystal microrotation vibration device, 13 is a sample to be measured, 14 is an X-ray detector, 15 is a phase sensitive detector, and 16 is a microrotation drive source. The phase sensitive detector 15 is
A device that measures physical quantities that vary with respect to the time axis by synchronizing them with a phase signal (called a reference signal). Specifically, a typical example is a lock-in amplifier used for microcurrent measurement, but in the present invention, a digital lock-in measurement is performed by applying a gate to an X-ray detector in synchronization with a reference signal. As the reference signal, a sine wave signal applied to the minute rotational drive source 16, for example a piezo element, is used.

The gist of this invention is to improve the precision of X-ray diffraction and absorption measurements by combining phase-sensitive detection of X-rays with a wavelength modulation method.

To explain its operation, the continuous X-rays emitted from the X-ray source 11 are made incident on the spectroscopic crystal micro-rotary oscillator 12 that rotates at an angular frequency ω, and after wavelength modulation is applied to the sample 13 to be measured. The X-ray detector 1 transmits the X-rays that are irradiated and diffracted and scattered by the sample to be measured 13.
4 to detect. The output of this X-ray detector 14 is measured by a phase sensitive detector 15 using the output of the minute rotation drive source 16 as a reference signal. Thereby, X-ray diffraction and scattering by the sample to be measured 13 can be measured with a good signal-to-noise ratio.

That is, the phase sensitive detector 15 functions to extract a signal with a certain regularity from irregular noise. This invention is effective in cases where the signal strength is weak and would be buried in noise in normal measurements, such as on surfaces or thin films. The signal-to-noise ratio can be improved by extracting and integrating signals that have regularity with respect to phase.

As explained above, the present invention is a method of obtaining spectroscopic X-rays of a specific wavelength or an integer multiple thereof using Bragg reflection, and performing X-ray measurements using the spectroscopic X-rays. Spectral X by giving
By modulating the X-rays and using the modulated spectroscopic X-rays, the background can be effectively removed and the signal-to-noise ratio is improved.
It has the advantage of being able to obtain highly accurate X-ray diffraction/scattering data at line wavelengths.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the operating principle of the present invention, and FIG. 2 is a block diagram showing an example of an X-ray measuring apparatus used for carrying out an embodiment of the present invention. In the figure, 1 and 11 are X-ray sources, 2 and 2' are spectroscopic crystals,
3 is a rotary table, 12 is a spectroscopic crystal micro-rotation vibration device,
13 is a sample to be measured, 14 is an X-ray detector, 15 is a phase sensitive detector, and 16 is a minute rotation drive source.

Claims (1)

[Claims] 1 When two parallel spectroscopic crystals are rotated by a small angle and monochromatic X-rays of a specific wave and a wavelength of an integral multiple thereof are obtained by using the flag reflection of X-rays by the spectroscopic crystal, the spectroscopic crystal is attached to the spectroscopic crystal. Micro-rotational vibration is applied by a micro-rotary vibration device, and two parallel spectroscopic crystals are rotated around the point of incidence of the monochromatic X-rays, thereby adding wavelength modulation to the monochromatic X-rays, and then irradiating the sample to be measured. , the X-rays diffracted and scattered by the sample to be measured are detected by an X-ray detector, and the X-rays from the X-ray detector are detected by a phase-sensitive detector using the output of the micro-rotational vibration source as a reference signal. An X-ray measurement method characterized by measuring X-ray diffraction, scattering, or absorption spectra.