JPH01296149A - Expanded x rays absorption fine structure measuring apparatus - Google Patents

Abstract

PURPOSE:To enable temperature dependent measurement from a low to high temperature, by detecting and feeding back a difference between a sample temperature and a set temperature measured with a temperature measuring element to a Peltier element to control current flowing therethrough. CONSTITUTION:After X rays radiated from an X-ray source 1 pass through a first slit 2, energy of incident X rays is controlled variably with a monochrometer 3 with respect to a sample 4 to be measured. Then, after passing through a second slit 5, the incident X rays with incident energy measured 6 are incident on a sample 4 held with a rotatable sample holder 7. Then, an absorption of the X rays transmitted through or reflected on the sample 4 are detected based on intensity of the X rays with an X rays detector 8. Then, a temperature measuring elements 11 is provided at a part of the holder 7 to detect the temperature of the sample 4 together with a Peltier element 10. A sample temperature data measured is taken into a temperature control means 12 to feed back a difference from a sample temperature set to the element 10 thereby permitting a variable control of the temperature of the sample 4.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an extension X for performing surface local structure analysis of substances.
This invention relates to a linear absorption fine structure measuring device.

Conventional technology In general, the extended X
Linear absorption fine structure (EXTended X-ray Ab
s.

rption fine structure (hereinafter abbreviated as "EXAFS") is important. this is,
By injecting monochromatic X-rays into a sample and continuously changing the wavelength, we measure the absorption edge of the atom of interest, for example, the fine structure spectrum of X-ray absorption that appears on the high energy side from the absorption edge. This is a structural analysis method in which the radial distribution around a specific atom of interest, that is, the type, number, coordination distance, etc. of the nearest and second neighboring atoms, is determined from the Fourier transform of the vibrational spectrum.

For example, a cryostat was used to perform cooling and suppress lattice vibrations, as disclosed in Japanese Patent Application Laid-open No. 6
This method is proposed in Japanese Patent No. 2-214335. In this case, according to the publication, because the sample is fixed at the tip of the cryostat,
It is necessary to be able to rotate the 0Q container with high precision. However, since it is a direct connection, a flexible connection method cannot be used. Therefore,
Vibration caused by bubbling in the cryostat, where bubbles are generated from liquid nitrogen, is transmitted to the sample, and the S/
Since N has deteriorated, there is no point in using cryot to suppress lattice vibrations due to cooling. Furthermore, even though the sample is cooled, it can only be cooled at a specific, fixed temperature such as the refrigerant temperature, specifically liquid nitrogen temperature or liquid helium temperature, and continuous temperature changes are not possible.

By the way, some conventional X-ray diffractometers have been able to perform continuous temperature measurements by controlling the sample temperature by combining liquid nitrogen cooling and heater heating in order to measure temperature dependence. Specifically, it is similar to the one described in the above publication and uses a lyostat, which is difficult to use.

Purpose The present invention was made in view of the above points, and an object of the present invention is to obtain an extended X-ray absorption fine structure measuring device that can easily measure the temperature dependence of a sample from low to high temperatures with a high S/N ratio. purpose.

Structure In order to achieve the above object, the present invention provides an X-ray generator that generates X-rays.
A radiation source, a monochromator that changes the energy of the X-rays irradiated onto the sample, a sample holder that holds the sample, and an X-ray detector that detects the X-rays transmitted or reflected from the sample, A Peltier element and a temperature measuring element for measuring the temperature of the sample are fixed to the sample holder, and the difference between the sample temperature measured by the temperature measuring element and the set temperature is detected and the Peltier element is The present invention is characterized in that it is provided with a temperature control means that feeds back the current to the Peltier element and controls the current flowing through the Peltier element.

Hereinafter, one embodiment of the present invention will be described based on the drawings. First, an X-ray source 1 that generates X-rays is provided. If the X-ray source 1 is one that emits synchrotron radiation, it will be possible to perform accurate measurements in an extremely short time.
It is not particularly limited as long as it can generate at least continuous X-rays (white X-rays). The X-rays emitted from the X-ray source 1 pass through the first slit 2 and then enter the monochromator 3, where the energy of the X-rays incident on the sample 4 to be measured is variably controlled. Here, the monochromator 3 may be a general one made of Si or the like,
Alternatively, a curved shape may be used to provide light condensing properties. Furthermore, after the xMA that has passed through the monochromator 3 passes through the second slit 5, the energy of the X-rays incident on the sample 4 is measured by an incident energy measuring device 6 before the xMA enters the sample 4. As this incident energy measuring device 6,
For example, what is called an ion chamber is used, and about 10% of the incident intensity is used for detection. Further, the sample 4 is held by a sample holder 7. Here, the sample 4 may be held so that the X-rays are transmitted through the sample 4 (transmission EXAF, which is the most common EXAFS method).
S method), or the X-rays may be held so as to be totally reflected on the surface of the sample 4 (total reflection EXAFS method or JP-A No. 6
Total internal reflection fluorescence E as shown in Japanese Patent No. 2-214335
(XAFS method), the sample holder 7 is rotatably provided so that these sample postures can be taken as appropriate. In addition, the beam diameter of the incident X-rays on the sample 4 is narrowed down to be less than the quantity by the slits 2 and 5 and the monochromator 3, and the sample holder 7 A hole is formed in a part of the hole. Furthermore, xfa, which is transmitted through the sample 4 or totally reflected on the surface of the sample 4) and whose negative portion is absorbed, is detected based on the X-ray intensity by the X-ray detector 8 for its absorption amount. Here, a proportional counter or a scintillation counter may be used as the X-ray detector 8, but considering high sensitivity, S
It is preferable to use a semiconductor detector referred to as SD. The amount of X-ray absorbed by the X-ray detector 8 is detected by measuring the difference between the incident energy and the incident energy detected by the incident energy measuring device 6 for each incident X-ray energy (for this reason, the monochromator 3 is controlled to detect the incident (the energy is varied) is calculated by the control calculation system 9.

Therefore, in this embodiment, a Vertier element 10 is provided fixed to a part of the sample holder 7. The attachment point of this Bertier element 10 to the sample holder 7 is
It is said that the position is outside the passing line of il. Here, as is well known, this Bertier element 10 has different types of conductors (
It is a heating/cooling element that utilizes the phenomenon that heat is generated or absorbed in addition to Joule heat at the contact when current is passed through the contact (or semiconductor), and it is currently small and lightweight with a size of several body angles or less. However, since the sample 4 held by the sample holder 7 is generally small, it can be sufficiently heated or cooled. Whether it is heated or cooled can be determined by changing the direction of the current flowing through the Beltier element 10.

Further, a thermal lightning pair 11 as a temperature measuring element for detecting the actual temperature of the sample 4 is also attached to a part of the sample holder 7. The sample temperature data measured by this thermocouple 11 is taken into the temperature control means 12 that controls the current (including direction) to the Bertier element 10, and the difference between the specified sample set temperature and the detected sample temperature is determined by the Bertier element. 1
A feedback control system is configured to provide feedback to zero.

According to such a configuration, the temperature of the sample 4 can be measured by the thermocouple 11.
- Temperature control means 12 - Variable control can be performed arbitrarily and easily by the feedback control system using the Bertier element 10, and the temperature dependence of the sample 4 ranging from low to high temperatures can be confirmed with a high S/N ratio. For example, atoms in a substance do not remain stationary at a fixed position, but actually oscillate thermally around an equilibrium position according to each temperature, and the effects of thermal oscillation appear during EXAFS measurements. According to this embodiment, the amount of influence due to such thermal vibrations can be easily measured.

The present invention is not limited to the exemplified transmission EXAFS method, but can be applied to all spectroscopic methods that use the absorption spectrum of X-rays, which is called the EXAFS method. It can also be applied to X-ray analysis equipment.

Effects As described above, the present invention uses a Bertier element to control the temperature of the sample, and the temperature control means performs feedback control of the Bertier element based on the temperature measurement by the sample temperature measuring element. It can be easily and continuously controlled from low temperature to high temperature in a short time with high accuracy. Therefore, it is possible to control the EXAFS of the sample to the desired sample temperature and perform high-sensitivity and high-speed measurement.
Furthermore, since it does not use a refrigerant like conventional methods, there is no need to worry about running out of refrigerant during measurement, and continuous measurement over a long period of time is possible.The device also uses a small Vertier element, so it can be small. becomes.

[Brief explanation of the drawing]

The drawing is a block diagram showing an embodiment of the present invention.

Claims (1)

[Claims] An X-ray source that generates X-rays, a monochromator that changes the energy of the X-rays irradiated onto a sample, a sample holder that holds the sample, a Peltier element fixed to the sample holder, and a Peltier element that controls the temperature of the sample. A temperature measuring element to be measured;
A temperature control means for detecting the difference between the sample temperature measured by the temperature measuring element and the set temperature and feeding it back to the Peltier element to control the current flowing through the Peltier element; An extended X-ray absorption fine structure measuring device comprising an X-ray detector that detects radiation.