JP3529065B2 - X-ray small angle scattering device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray small angle scattering device for measuring a change in the intensity of scattered X-rays in a small angle region centered on the optical axis of incident X-rays.

[0002]

2. Description of the Related Art Depending on a substance, scattered X-rays may be generated in a small angle region around the optical axis of the incident X-ray, for example, an angle region of about 0 ° to 5 ° when the substance is irradiated with X-rays. is there. For example, when fine particles of about 10 to 1000 Å or a non-uniform region having a density corresponding to this exist in the substance, diffuse scattering in the incident line direction, so-called central scattering occurs. This central scattering is irrelevant to the internal structure of the particle and spreads as the particle becomes smaller. This scattering exists regardless of whether it is crystalline or amorphous, and the scattering angle, that is, the incident X
It is observed in a small angle region where the angle from the optical axis of the line is about 0 ° to 5 °. In addition to the above central scattering in the small angle region, Bragg reflection when the lattice spacing is very large like a protein crystal, and crystalline and amorphous are periodically arranged in a fiber sample. , X-ray diffraction and the like in the case of so-called long-period structure are observed. The X-rays observed in the small angle region, including the central scattering, Bragg reflection and X-ray diffraction as described above, are generally called small angle scattering.

The X-ray small angle scattering device of the present invention is a device for measuring such small angle scattering. Since this X-ray small-angle scattering device measures weak scattered X-rays generated from the sample, it is necessary to eliminate as much as possible parasitic scattering that lowers the resolution and the S / N ratio. Here, the resolution is considered to be a small angle resolution indicating how small a scattered X-ray can be measured and an angular resolution necessary for separating adjacent diffracted rays for measurement. Both resolutions need to be kept high. Parasitic scattering is X-rays observed when a sample is removed from the X-ray measurement system, and is excited by diffused scattering from optical elements exposed to scattered X-rays or white X-rays. It is considered that fluorescent X-rays and the like are the main causes.

In order to realize the above-mentioned measurement with high accuracy, various types of small-angle X-ray scattering devices have been conventionally known. For example, a counter method of detecting scattered X-rays by an X-ray counter that swivels around the sample, so-called 2θ scanning movement, or an X-ray film or the like is fixedly arranged at the rear position of the sample, and the scattered X-rays are A camera method for displaying an X-ray image on an X-ray film is known. In the small-angle scattering measurement using the camera method, as shown in FIG. 9, the sample S is irradiated with an X-ray beam R focused in almost parallel, and scattered X-rays generated from the sample S in response to the X-ray irradiation. For example, the X-ray film 51 is exposed. Scattered X
The X-ray image A corresponding to the line appears in the small angle region 0 ° to ± α on the X-ray film 51, and by observing the X-ray image A, the property of the sample S can be determined.

[0005]

The X-ray film 51 is located on the central axis of the X-ray beam R, that is, on the optical axis.
In general, a beam stopper 52 is provided at a position in front of the X-ray film 51 in order to prevent the X-ray film 51 from being damaged by the direct beam and the strong X-rays hitting the X-ray film 51. The beam stopper 52 contains lead or the like and blocks passage of almost all X-rays.
However, if the beam stopper is provided in this way,
The X-ray image is removed at the minimum angle region β of the X-ray film 51 corresponding to the beam stopper. In small-angle scattering measurement using the camera method, it is common to set the incident position of the direct beam to the reference angular position of the X-ray detector, that is, the 0 ° position. If the line image is erased, the reference angular position cannot be accurately determined, which causes a problem that the accuracy of detecting the position of the scattering angle deteriorates.

On the other hand, scattered X-rays generated from the sample S include those with extremely high intensity and those with extremely low intensity. In measuring small-angle scattering, it is desirable to detect a wide range of scattering intensities from strong scattering to weak scattering. In order to reliably detect weakly scattered rays, it is necessary to lengthen the measurement time and the X-ray exposure time to the X-ray detector. However, if the measurement time is set too long, X-rays will be generated at the strong scattered X-rays.
The line detector is overexposed. Beam stopper 5
2 also aims to eliminate such excess X-ray intensity. However, even such intense X-rays may contain important scattered X-ray information, and removing such important information reduces measurement reliability. Become. Of course, the area of the beam stopper 52 can be adjusted to guide the scattered X-ray information of high intensity to the X-ray detector 51. In that case, the intensity of the scattered X-ray of high intensity is detected by the X-ray detector. 51
The measurement time cannot be set too long in order not to exceed the allowable strength of. Then, the X-ray detector cannot be sufficiently exposed by the scattered X-ray having a weak intensity, and accurate scattered X-ray information on that portion cannot be obtained. That is, in the conventional small-angle X-ray scattering measurement using the beam stopper, it was not possible to uniformly obtain scattered X-ray information in a wide intensity range from scattered X-rays of low intensity to scattered X-rays of high intensity.

The present invention has been made in order to solve the above-mentioned problems, and can directly measure a direct beam, and yet, from a very weak scattered X-ray to a very strong scattered X-ray.
It is an object of the present invention to provide an X-ray small-angle scattering device capable of detecting scattered X-rays in a wide intensity range up to a line.

[0008]

In order to achieve the above object, an X-ray small angle scattering apparatus according to the present invention is arranged at a rear position of a sample S with respect to a traveling direction of X-rays R, as shown in FIG. 1, for example. Between the sample S and the X-ray detector 1, and the X-ray detector 1 for detecting the X-rays in a linear or planar manner.
And an X-ray absorption plate 2a arranged on the path of the direct beam immediately in front of the line detector 1 .
The area is gradually increased toward the X-ray detector .

The X-ray absorbing plate is a material that allows X-rays to pass therethrough after being attenuated by an appropriate intensity, and can be made of, for example, aluminum. With this X-ray absorbing plate, for example, X-rays having an intensity of about 10 ¹⁰ cps are attenuated to X-rays having an intensity of about 10 ⁵ to 10 ⁴ cps. This X-ray attenuation amount can be freely determined by appropriately setting the material of the X-ray absorbing plate or the thickness in the X-ray passing direction.

Further, the fact that the X-ray absorption plate is arranged "in front of the X-ray detector" means that the X-ray absorption plate is as close to the X-ray absorption plate as possible.
This means that it is arranged near the line detector, and specifically, it is 100 μm or less, preferably 50 μm or less. Most preferably, the X-ray absorption plate is brought into contact with the X-ray detection surface of the X-ray detector.

The X-ray absorption plate 2a is an X-ray detector 1 with the direct beam and the strong X-rays appropriately attenuated.
Therefore, the X-ray detector 1 can detect X-rays even in the direct beam and the minimum angle region β corresponding to high-intensity X-rays.
A line image A1 is obtained. In this way, the X-ray image corresponding to the direct beam is directly obtained in the minimum angle region β,
The reference angular position for the scattering angle on the X-ray detector, ie the 0 ° position, can be determined easily and accurately. Further, since the high-intensity X-rays are attenuated by the X-ray absorption plate 2a and guided to the X-ray detector 1, the X-ray detector 1 is not damaged even if the measurement time is long. The long measurement time means that scattered X-rays with low intensity can be sufficiently exposed to the X-ray detector 1, and as a result, weak scattered X-rays can be obtained.
X-ray scattering in a wide range of intensity from X-ray to strong X-ray
Can detect lines. That is, the range of the minimum value and the maximum value that can be detected, that is, the dynamic range can be widened. At this time, the intensity level of the strong scattered X-ray becomes small due to the action of the X-ray absorbing plate 2a, but it can be sufficiently utilized as X-ray information.

Since a two-dimensional X-ray detector such as an X-ray film or a stimulable phosphor is assumed as the X-ray detector 1 in FIG. 1, the thickness in the X-ray traveling direction is shown thin. . However, instead of this two-dimensional X-ray detector,
When a one-dimensional X-ray detector such as PSPC is used, its thickness becomes even thicker.

An X-ray detector for linearly detecting X-rays is a so-called one-dimensional X-ray detector, for example, P
SPC (Position Sensitive Proportional Counter:
A position sensitive X-ray detector) can be used. This P
Since the SPC itself is well known, a detailed description thereof will be omitted, but if an example thereof is briefly described, it has an anode line 31, a cathode line 32, and a delay line 33 inside, for example, as shown in FIG. . PS through the X-ray acquisition window 34
When an X-ray enters the PC 35, electric charges are induced in the cathode line 32, and electric pulse signals corresponding to the electric charges appear at both ends of the delay line 33. X-rays are detected by measuring the pulse signal. The pulse signals appearing at both ends of the delay line 33 have a time difference proportional to the distance in the length direction x. Therefore, the X-ray incident position in the length direction x can be known by measuring the time difference between the pulse signals generated at both ends of the delay line 33. In other words, PSPC
35 detects the intensity and angular position of each X-ray incident on the PSPC 35 at substantially the same position in the length direction x, that is, the scattering angle direction 2θ within the range in which the anode wire 31 is stretched.

An X-ray detector for detecting X-rays in a plane is a so-called two-dimensional X-ray detector, which is exposed to X-rays to form a latent image on that portion and develops it by developing processing. An X-ray film capable of forming an image, an X-ray sensitive material called a so-called stimulable phosphor, or the like can be used. A stimulable phosphor is an X-ray sensitive material also called a stimulable phosphor, which can store X-rays and the like in the form of energy. It is an object that has the property of being emitted as light to the outside. That is, when the stimulable phosphor is irradiated with radiation such as X-rays, energy is accumulated as a latent image in the stimulable phosphor corresponding to the irradiated portion, and the stimulable phosphor is further stimulated by laser light. When the excitation light is irradiated, the latent image energy becomes light and is emitted to the outside.

As the X-ray absorption plate, it is desirable to use an X-ray absorption plate whose area gradually increases toward the X-ray detector 1 as shown by reference numeral 2b in FIG . If such an X-ray absorption plate is used, the direct beam can be reliably blocked by increasing the thickness of the X-ray absorption plate in the central portion of the minimum angle region β corresponding to the direct beam, and further, By making the thickness of the X-ray absorption plate 2b corresponding to the wide angle side γ in the minimum angle region β smaller than that of the central portion, the scattering X particularly in the wide angle side γ.
The line information can be reproduced with high accuracy. In the case of a single-plate X-ray absorption plate as shown in FIG. 1, the scattered X-ray information in the wide-angle side γ part is also uniformly greatly attenuated, but as shown in FIG. By increasing or decreasing in stages, such a lack of scattered X-ray information can be avoided.

According to the invention, an X is placed in front of the X-ray detector.
When the X-ray absorption plate is provided, fluorescent X-rays may be generated from the X-ray absorption plate when the X-ray absorption plate strikes the X-ray absorption plate. If this fluorescent X-ray is taken into the X-ray detector, it becomes a noise component with respect to the scattered X-ray image that should be originally obtained, and the S / N ratio of the measurement result deteriorates, which is not preferable. Therefore, as shown in FIGS. 1 and 2, by providing a filter 3 on the X-ray detection surface of the X-ray detector 1, the X-ray absorption plates 2a, 2b are provided.
It is desirable to absorb the fluorescent X-rays generated from the X-ray detector before reaching the X-ray detector 1. As shown in FIG. 3, as the X-ray detector 1, a square or rectangular two-dimensional X-ray detector 11, for example, when a stimulable phosphor or an X-ray film is used, the two-dimensional X-ray detector 11 is used. Is covered with the filter 3. This filter can be formed of, for example, a polymer film such as polyethylene or black paper.

When the incident X-ray is shaped into an X-ray beam having a substantially circular cross section through a pinhole, the X-ray absorbing plate is formed in a circular shape as indicated by reference numeral 2b in FIG. On the other hand, when the incident X-ray beam is shaped into an X-ray beam having a rectangular cross section through the line slit, the X-ray absorption plate is also formed in a rectangular shape.

[0018]

DETAILED DESCRIPTION OF THE INVENTION

(First Embodiment) FIG. 5 shows an embodiment in which the present invention is applied to an X-ray small-angle scattering apparatus using a line-slit parallel bundle optical system. The X-ray small-angle scattering device shown here is a type of X-ray small-angle scattering device that forms incident X-rays into parallel beams using a plurality of line slits. This X
The small line angle scattering device includes an X-ray focal point F for generating X-rays, a slit optical system 4, a sample S to be measured, a stimulable phosphor 21 as an X-ray detector, and a stimulable phosphor 21. Filter 3 covering the X-ray detection surface and direct beam R
_The X-ray absorption plate 2 is arranged on the traveling path of _D. The slit optical system 4 has a first line slit 4a, a second line slit 4b, and a third line slit 4c. The line slit is a slit having a rectangular X-ray passage opening with a narrow width and a long length. The X-ray absorbing plate 2 may have a single plate shape as shown by reference numeral 2a in FIG. 1 or may have a shape as shown by reference numeral 2b in FIG. .

In this X-ray small-angle scattering device, the divergence of X-rays emitted from the X-ray focal point F is restricted by the first line slit 4a and the second line slit 4b, and the X-rays are almost parallel to each other.
A line beam is formed, and scattered X-rays from each line slit are removed by the third line slit. The obtained parallel X-ray beam becomes a direct beam and the sample S
After passing through the X-ray absorbing plate 2, a part thereof is absorbed by the X-ray absorbing plate 2, and the remaining part which is not absorbed is transmitted through the X-ray absorbing plate 2 to expose the stimulable phosphor 21. The scattered X-rays generated from the sample S in response to the incident X-rays are stimulable phosphor 21.
To reach and expose it. The latent image energy is accumulated in the exposed portion of the stimulable phosphor 21 exposed by the scattered X-rays. After a lapse of a predetermined measurement time, the stimulable phosphor 21 is carried to a predetermined reading place and a well-known reading process using stimulated excitation light such as laser light is performed to determine what scattering angle position and how much. It is read whether strong scattered X-rays are generated, and the property of the sample S is specified based on the read result.

By arranging the X-ray absorbing plate 2 on the traveling path of the direct beam R _D , it is possible to directly form an X-ray image corresponding to the direct beam at the central position of the stimulable phosphor 21, and the vicinity of the direct beam. By appropriately attenuating the intensity of high-intensity scattered X-rays, damage to the stimulable phosphor 21 can be prevented even if the measurement time is lengthened.
As described above with reference to FIGS. 1 and 2. The fact that the X-ray image corresponding to the direct beam can be directly formed means that the reference angular position of the X-ray detector 21, that is, 0.
This means that the ° position can be specified easily and accurately.
In addition, the fact that the measurement time can be set long means that scattered X-rays with low intensity can be sufficiently exposed to the X-ray detector 21, and as a result, measurement with a wide dynamic range can be performed. is there.

The resolution can be improved by increasing the distance between the sample S and the stimulable phosphor 21.
Further, if the distance between the sample S and the stimulable phosphor 21 is lengthened, the air scattering of X-rays increases and the background rises, so that the S / N ratio of the measurement result may deteriorate. . In order to eliminate this, it is desirable to cover the space between the sample S and the stimulable phosphor 21 with a vacuum path.

(Second Embodiment) FIG. 6 shows an embodiment in which the present invention is applied to an X-ray small-angle scattering apparatus using a pinhole parallel bundle optical system. In this small-angle X-ray scattering device, the X-rays emitted from the X-ray focus F are pinholes 5
The sample S is irradiated with the parallel X-ray beam by forming a substantially parallel X-ray beam by narrowing down with a and 5b. The structure on the rear side (right side in the drawing) of the sample S and the action corresponding to the structure are the same as those of the embodiment shown in FIG.

(Third Embodiment) FIG. 7 shows an embodiment in which the present invention is applied to an X-ray small-angle scattering apparatus using a crack U-slit. In this X-ray small angle scattering device, the X-rays emitted from the X-ray focal point F are applied to the sample S in a state of being narrowed down by using the crack U-slit 6 which is a block slit and the bridge member 7. Cracky U
Since the slit 6 can efficiently remove the parasitic scattering on one side thereof, the resolution can be improved. The structure on the rear side (right side in the drawing) of the sample S and the action corresponding to the structure are the same as those of the embodiment shown in FIG.

(Fourth Embodiment) FIG. 8 shows an embodiment in which the present invention is applied to an X-ray small angle scattering device using a channel cut monochromator. In this small-angle X-ray scattering device, the X-ray emitted from the X-ray focal point F is shaped into a monochromatic X-ray beam having a high degree of parallelism by the channel cut monochromator 8, and the parallel beam is applied to the sample S. The channel cut monochromator 8 is a monochromator known per se, and is formed, for example, by processing a perfect crystal such as germanium or silicon and cutting a groove. By reflecting the X-rays by the pair of X-ray reflecting surfaces formed on both sides of the groove, a highly accurate monochromatic parallel beam can be obtained. The structure on the rear side (right side in the drawing) of the sample S and the action corresponding to the structure are the same as those of the embodiment shown in FIG.

(Other Embodiments) The present invention has been described above with reference to the preferred examples, but the present invention is not limited to these examples and is within the technical scope described in the claims. Can be modified in various ways. For example, in the embodiment shown in FIGS. 5 to 8, a stimulable phosphor that is a two-dimensional X-ray detector is used as the X-ray detector, but instead of this,
Other two-dimensional X-ray detectors such as X-ray film can be used, or the PSPC3 shown in FIG.
It is also possible to use a one-dimensional X-ray detector such as the one shown in FIG. Further, when the area of the X-ray absorbing plate 2b is changed stepwise as shown in FIG. 2, the number of steps is not limited to three as shown in the figure, and it may be two or more.

[0026]

According to the X-ray small angle scattering device of the present invention , the direct beam and the high-intensity X-rays are received by the X-ray detector in a state where the intensity thereof is attenuated by the X-ray absorbing plate. Since the X-ray image corresponding to the direct beam is directly obtained, the reference angular position regarding the scattering angle on the X-ray detector, that is, the 0 ° position can be easily and accurately determined. Further, since the high-intensity X-ray is guided to the X-ray detector in a attenuated state, the X-ray detector is not damaged even if the measurement time is long. The long measurement time means that the scattered X-rays with low intensity can be sufficiently exposed to the X-ray detector, and as a result, the scattered X-rays can be scattered over a wide intensity range from weak scattered X-rays to strong scattered X-rays. Can detect lines. That is, the range of the minimum value and the maximum value that can be detected, that is, the dynamic range can be widened.

Further, according to the X-ray small angle scattering device of the present invention.
If so, the area of the X-ray absorption plate gradually increases toward the X-ray detector.
As it becomes larger,
The degree of attenuation for high intensity scattered X-rays
By making the beam smaller than that,
And strong X-rays can be measured stepwise at the same measurement time.
It This can greatly increase the measurement time,
As a result, the dynamic range can be further expanded.
Wear.

In the X-ray small angle scattering device according to the present invention,
A filter for absorbing the fluorescent X-rays generated from the X-ray absorption plate.
Filter is provided on the X-ray detection surface of the X-ray detector,
Fluorescent X-rays generated from the X-ray absorption plate are taken into the X-ray detector
Good measurement results with high S / N ratio
Can be obtained.

In the X-ray small angle scattering device according to the present invention,
If the X-ray absorption plate is placed in contact with the X-ray detector, X-rays
Substantially eliminating the distance between the absorber and the X-ray detector
Therefore, the resolution can be further improved.

[0030]

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of an X-ray small angle scattering device according to the present invention.

FIG. 2 is a cross-sectional view showing a main part of another embodiment of an X-ray small-angle scattering device according to the present invention.

FIG. 3 is a front view showing an example of an X-ray detector.

FIG. 4 is a diagram showing an example of an X-ray absorption plate.

FIG. 5 is a diagram schematically showing an embodiment of an X-ray small-angle scattering device according to the present invention.

FIG. 6 is a diagram schematically showing another embodiment of the X-ray small angle scattering device according to the present invention.

FIG. 7 is a diagram schematically showing still another embodiment of an X-ray small-angle scattering device according to the present invention.

FIG. 8 is a diagram schematically showing still another embodiment of an X-ray small angle scattering device according to the present invention.

FIG. 9 is a diagram schematically showing a main part of an example of a conventional small-angle X-ray scattering device.

FIG. 10 is a perspective view showing another example of an X-ray detector.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 X-ray detector 2 X-ray absorption plate 2a Single plate X-ray absorption plate 2b Stepwise X-ray absorption plate 3 Fluorescent X-ray cut filter 4 Slit optical system 4a-4c Line slits 5a, 5b Pinhole 6 Cracki U slit 7 Bridge member 8 Channel cut monochromator 11 Two-dimensional X-ray detector 21 Accumulable phosphor 35 PSPC (One-dimensional X-ray detector) F X-ray focus A X-ray image S Sample R _D Direct beam α Small angle area β Small angle region

Continuation of the front page (56) References JP-A-6-130002 (JP, A) Fukukaihei 3-90068 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01N 23 / 00-23/227

Claims (2)

(57) [Claims] 1. An X-ray small angle scattering device for measuring a change in the intensity of scattered X-rays in a small angle region centered on the optical axis of incident X-rays, the device being arranged at a rear position of a sample with respect to a traveling direction of X-rays. X-ray detector for linearly or planarly detecting X-rays, and an X-ray arranged between the sample and the X-ray detector and on the path of the direct beam immediately before the X-ray detector. An absorption plate, and the area of the X-ray absorption plate is gradually increased toward the X-ray detector.
A small-angle X-ray scattering device characterized by an increase in size . 2. The X-ray small angle scattering device according to claim 1, wherein a filter for absorbing fluorescent X-rays generated from the X-ray absorption plate is provided on the X-ray detection surface of the X-ray detector. Characteristic X-ray small angle scattering device.