JP2015121486A - Microcrystal structure analysis method and microcrystal structure analysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microcrystal structure analysis method and a microcrystal structure analysis device which can perform structural analysis of microcrystal with a simple configuration.SOLUTION: A microcrystal structure analysis method comprises: a first detection step ST1 for detecting a first diffraction image of an X-ray irradiated to a specimen container in a state where the specimen container in which the microcrystal is suspended is rotated at constant speed with respect to a magnetic field generation part; a second detection step ST2 for detecting a second diffraction image of the X-ray irradiated to the specimen container in a state where the rotation of the specimen container is stopped with respect to the magnetic field generation part; first determination steps ST3, ST4, ST5 for determining the crystal system of the microcrystal, grating constant, Miller index and space group on the basis of the detected first diffraction image and second diffraction image; a second determination step ST6 for determining the diffraction intensity of the diffraction spot in each determined Miller index on the basis of the first diffraction image and the second diffraction image; and an analysis step ST7 for performing analysis processing on the basis of the determined diffraction intensity.

Description

  The present invention relates to a microcrystal structure analysis method and a microcrystal structure analysis apparatus.

X-ray structural analysis is known as a technique for analyzing the crystal structure of an object. This X-ray structural analysis is usually performed using a single crystal or microcrystal powder (hereinafter simply referred to as “microcrystal”) of about 100 μm or more. In recent years, a method has been developed in which microcrystals suspended in a sample are three-dimensionally oriented and analyzed in a quasi-single crystal state.
With respect to this method, conventionally, after applying a time-varying magnetic field to a sample in which microcrystals are suspended to make the microcrystals three-dimensionally oriented (pseudo-single crystallization), the suspension medium is UV-cured. A method is known in which analysis is performed with the orientation of microcrystals fixed (see, for example, Patent Document 1).

  In the microcrystal structure analysis method described in Patent Document 1, the microcrystal is three-dimensionally oriented (pseudo-single crystallization) by rotating the sample in which the microcrystal is suspended with respect to the magnetic field generator, and the rotation is performed. The X-ray diffraction image of the quasi-single crystal is obtained by continuously irradiating the sample with X-rays and detecting the X-ray transmitted through the sample and diffracted by the X-ray detector. At that time, the X-ray shielding device shields X-ray irradiation when a specific part that is a part of the rotation direction of the sample does not face the desired direction, and when the specific part faces the desired direction. Only X-ray irradiation is allowed. As a result, the X-ray diffracted through the sample with the specific portion facing the desired direction can be intermittently detected by the X-ray detector, so that the pseudo-single crystal sample is rotated. However, a good X-ray diffraction image can be obtained.

International Publication No. 2013/118761 Pamphlet

However, the microcrystal structure analysis method requires an X-ray shielding device for shielding and allowing X-ray irradiation while rotating the sample, so that the entire analysis device becomes large and the manufacturing cost increases. There was a problem to do.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a microcrystal structure analysis method and a microcrystal structure analysis apparatus that can perform microcrystal structure analysis with a simple configuration.

  According to the microcrystal structure analysis method of the present invention, the first diffraction image of the radiation irradiated to the sample is detected in a state where the sample in which the microcrystal is suspended is rotated at a constant speed with respect to a magnetic field or an electric field. A first detection step; a second detection step of detecting a second diffraction image of the radiation applied to the sample in a state where the rotation of the sample is stopped with respect to a magnetic field or an electric field; and the detected first diffraction image And a first determination step for determining a crystal system, a lattice constant, a plane index, and a space group of the microcrystal based on at least one diffraction image of the second diffraction image, and based on the at least one diffraction image. A second determination step of determining the diffraction intensity of the diffraction spot at each determined plane index, and an analysis step of performing an analysis process based on the determined diffraction intensity.

  According to the microcrystal structure analysis method of the present invention, the first diffraction image of the radiation irradiated with the sample in which the microcrystal is suspended is rotated with respect to the magnetic field or the electric field, and the sample is applied to the magnetic field or the electric field. In order to analyze the structure of the microcrystal based on at least one of the second diffraction images of the radiation irradiated with the rotation stopped, radiation (X-rays) while rotating the sample as in the past. Therefore, a shielding device for shielding and permitting the irradiation is not required, and the structure analysis of the microcrystal can be performed with a simple configuration.

  In the first determining step, the crystal system is preferably determined based on a diffraction spot and a layer line obtained from the at least one diffraction image. In this case, the crystal system of the microcrystal can be easily determined.

  In the first determination step, it is preferable to determine the lattice constant based on a layer line obtained from the at least one diffraction image. In this case, the lattice constant of the microcrystal can be easily determined.

  From another viewpoint, the microcrystal structure analysis apparatus of the present invention is capable of rotating the sample at a constant speed in a state where a magnetic field or an electric field is applied to a magnetic field or electric field generating unit and a sample in which the microcrystal is suspended. A sample source, a radiation source capable of irradiating the sample with radiation while the sample is rotated and stopped by the sample driver, and the sample in the rotated state. A diffraction image detection unit capable of detecting at least one diffraction image of the first diffraction image of the emitted radiation and the second diffraction image of the radiation irradiated to the sample in the rotation stopped state. It is characterized by that.

  According to the microcrystal structure analysis apparatus of the present invention, the first diffraction image of the radiation irradiated with the sample in which the microcrystals are suspended being rotated with respect to the magnetic field or electric field generation unit, and the sample to the generation unit On the other hand, the structure of the microcrystal is analyzed based on at least one of the second diffraction images of the radiation irradiated with the rotation stopped, so that the radiation (X The shielding device for shielding and allowing the irradiation of the (line) is not required, and the structural analysis of the microcrystal can be performed with a simple configuration.

  According to the present invention, the structural analysis of microcrystals can be performed with a simple configuration.

It is a schematic block diagram which shows the microcrystal structure analysis apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows the magnetization axis of a microcrystal. It is a perspective view explaining the orientation of the microcrystal in a rotating magnetic field and a static magnetic field. It is A arrow line view of FIG. 1 which shows a microcrystal structure analysis apparatus. It is a drawing substitute photograph which shows the 1st diffraction image of the X-ray in a rotating magnetic field. It is a drawing substitute photograph which shows the 2nd diffraction image of the X-ray in a static magnetic field. It is a flowchart which shows the microcrystal structure analysis method using a microcrystal structure analyzer. It is a table | surface which shows the relationship between a crystal system and a lattice constant. It is a table | surface which shows the relationship between a crystal system and a space group. It is a table | surface which shows the calculated value and measured value of the diffraction intensity in each surface index | exponent of a 1st diffraction image and a 2nd diffraction image. It is the graph which compared the calculated value and measured value of each diffraction intensity shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a microcrystalline structure analysis apparatus according to an embodiment of the present invention. In FIG. 1, a microcrystal structure analysis apparatus 1 includes a microcrystal orientation apparatus 10 that applies a magnetic field to a sample container 2 placed at a predetermined position. The sample container 2 is formed in, for example, a bottomed cylindrical shape, and suspends microcrystals 3 (see FIG. 2) of organic compounds, inorganic compounds, biological materials, etc. in the fields of medicine, biotechnology, polymer materials, and the like. The sample is stored.

  Most of the microcrystals 3 are biaxial crystals (orthorhombic, monoclinic, and triclinic) having different magnetic susceptibility in three directions orthogonal to each other, and have magnetic biaxial anisotropy. FIG. 2 is a perspective view showing the magnetization axis of an orthorhombic crystallite 3 as an example. As shown in FIG. 2, the microcrystal 3 which is an orthorhombic crystal has three different magnetic susceptibilities χ1, χ2, and χ3 in each of the three axial directions, and has a magnitude relationship of χ1> χ2> χ3. Hereinafter, the axis of the magnetic susceptibility χ1 is called an easy axis, the axis of the magnetic susceptibility χ2 is called an intermediate axis, and the axis of the magnetic susceptibility χ3 is called a hard axis.

  In FIG. 1, the microcrystal orientation apparatus 10 includes a base 11, a rotary base 12 provided on the base 11, and a magnetic field generator 13 that is a magnetic field generator provided on the rotary base 12. And a sample driving unit 14 capable of rotating the sample container 2 at a constant speed with respect to the magnetic field generating unit 13.

  The turntable 12 is mounted on the base 11 so as to rotate around a sample container 2 held by a chuck 15 (described later) by an actuator (not shown). Thereby, the direction of the sample container 2 can be arbitrarily adjusted with respect to the X-ray (radiation) R irradiated toward the sample container 2 from an X-ray source (see FIG. 4) described later.

  A support member 16 formed in a U shape in a side view is fixed on the turntable 12. The support member 16 has a pair of upper and lower horizontal portions 16a and 16b and a vertical portion 16c that connects the ends of the horizontal portions 16a and 16b.

  The magnetic field generator 13 includes a permanent magnet 13 a fixed to the lower surface of the horizontal portion 16 a of the support member 16 and a permanent magnet 13 b fixed to the upper surface of the horizontal portion 16 b of the support member 16. Each permanent magnet 13a, 13b is arranged so that the N pole and the S pole face each other. A space S for arranging the sample container 2 is formed between the permanent magnets 13a and 13b.

  The sample driving unit 14 includes, for example, a stepping motor, and the output shaft 14a penetrates the vertical portion 16c of the support member 16 in the horizontal direction and is rotatably supported by the vertical portion 16c. A chuck 15 that holds the sample container 2 is attached to the tip of the output shaft 14a. Accordingly, when the sample driving unit 14 is driven, the sample container 2 rotates in one direction (arrow D direction) with respect to the fixed magnetic field generating unit 13 via the output shaft 14a and the chuck 15. Yes. At that time, the rotation speed of the sample container 2 is set to a speed necessary for forming a rotating magnetic field.

Thereby, the microcrystals 3 suspended in the sample container 2 are randomly arranged as shown in FIG. 3A by forming a rotating magnetic field with the sample container 2 rotated. Thus, as shown in FIG. 3B, the magnetization difficult axis of the microcrystal 3 is oriented in the z-axis direction perpendicular to the xy plane (rotation plane).
Further, since the static magnetic field is formed in the state where the rotation of the sample container 2 is stopped, the microcrystal 3 is shown in FIG. 3C from a state where it is randomly arranged as shown in FIG. Thus, the easy axis of magnetization of the microcrystal 3 is oriented parallel to the x-axis direction.

  FIG. 4 is a view taken along the arrow A in FIG. In FIG. 4, the microcrystal structure analysis apparatus 1 includes an X-ray source (radiation source) 21 that irradiates a sample container 2 with X-rays R in order to perform an X-ray structure analysis of the microcrystal 3, and a sample container 2. And a diffraction image detector 23 that detects a diffraction image of the irradiated X-ray R.

  The X-ray source 21 irradiates the sample container 2 held by the sample driving unit 14 with X-rays while the sample container 2 is rotated and stopped. The X-ray R radiated from the X-ray source 21 passes through the collimator 22 and is in a direction orthogonal to the rotation axis C with respect to the rotating sample container 2 held by the sample driving unit 14, or Irradiated from directions other than 90 °.

  The diffraction image detector 23 is made of, for example, an imaging plate, and the first diffraction image 24 (see FIG. 5) of the X-ray R irradiated on the sample container 2 rotated by the sample driver 14 and the sample driver 14. The second diffraction image 25 (see FIG. 6) of the X-ray R irradiated to the sample container 2 in a state where the rotation due to is stopped is detected. Thereby, the diffraction image detection unit 23 can obtain the first diffraction image 24 in the rotating magnetic field and the second diffraction image 25 in the static magnetic field. The first diffraction image 24 in FIG. 5 is a diffraction image when the vertical direction in the drawing is the magnetic field direction B and the horizontal direction in the drawing is the rotation axis C direction, and the second diffraction image 25 in FIG. The diffraction image when the vertical direction in the figure is the magnetic field direction B.

FIG. 7 is a flowchart showing a microcrystal structure analysis method using the microcrystal structure analyzer 1. Hereinafter, the microcrystal structure analysis method of the present embodiment will be described with reference to FIG.
As shown in FIG. 7, first, the diffraction image detector 23 detects the first diffraction image 24 in the rotating magnetic field (first detection step, step ST1). Specifically, as shown in FIG. 1, in a state where the sample container 2 in which the microcrystal 3 is suspended is held by the chuck 15, the sample driving unit 14 is driven, and the sample container 2 is moved to the magnetic field generating unit 13. And rotate around the rotation axis C at a constant speed. As a result of the formation of a rotating magnetic field, the microcrystal 3 in the sample container 2 is oriented in the z-axis direction in which the hard axis of magnetization is perpendicular to the xy plane (rotation plane) as shown in FIG. Is done. In this state, as shown in FIG. 4, X-ray R is irradiated from the X-ray source 21, and the first diffraction image 24 of the X-ray R irradiated to the sample container 2 is detected by the diffraction image detector 23.

  Next, the diffraction image detection unit 23 detects the second diffraction image 25 in the static magnetic field (second detection step, step ST2). Specifically, first, the rotation of the sample container 2 by the sample driving unit 14 is stopped to form a static magnetic field. Thereby, in the microcrystal 3 in the sample container 2, as shown in FIG. 3C, the easy axis of magnetization of the microcrystal 3 is oriented parallel to the x-axis direction. In this state, as shown in FIG. 4, X-ray R is emitted from the X-ray source 21, and the diffraction image detector 23 detects the second diffraction image 25 of the X-ray R irradiated on the sample container 2. Step ST2 may be performed before step ST1.

  In FIG. 7, next, the crystal system of the microcrystal 3 is determined based on the first diffraction image 24 and the second diffraction image 25 obtained by the diffraction image detector 23 (step ST3). As shown in FIG. 8, the crystal system consists of cubic, tetragonal, orthorhombic (tetragonal), monoclinic, triclinic, hexagonal and trigonal. In step ST3, based on the layer line H (see FIGS. 5 and 6) obtained from the first diffraction image 24 and the second diffraction image 25, the crystal system of the microcrystal 3 is determined by selecting from these seven. . Here, the layer line H is a line connecting a plurality of diffraction spots P (black dots in FIGS. 5 and 6) appearing in the diffraction image.

Specifically, when the diffraction spot P appears in both the first diffraction image 24 and the second diffraction image 25, it is determined as follows. That is, when the layer line H is obtained from either the first diffraction image 24 or the second diffraction image 25, the crystal system is determined to be orthorhombic. When the layer line H is obtained from only one of the first diffraction image 24 and the second diffraction image 25, the crystal system has a χ1 axis (easy magnetization axis) or a χ3 axis (magnetization difficulty axis) b axis ( It is determined as a monoclinic crystal which becomes the vertical axis in FIG. Further, when the layer line H is not obtained from either the first diffraction image 24 or the second diffraction image 25, the crystal system is determined as a monoclinic crystal or a triclinic crystal whose χ2 axis (intermediate axis) is the b axis. Is done.
On the other hand, when the diffraction spot P appears in one of the first diffraction image 24 and the second diffraction image 25, the crystal system is determined to be any one of tetragonal crystal, hexagonal crystal, and trigonal crystal. Further, in both the first diffraction image 24 and the second diffraction image 25, when the ring shape appears without the diffraction spot P appearing, the crystal system is determined as a cubic crystal.

  In FIG. 7, when the crystal system of the microcrystal 3 is determined in step ST3, the lattice constant and the plane index of the microcrystal 3 are then determined (step ST4). As shown in FIG. 2, the lattice constant is made up of the lengths a, b, c of the sides of the microcrystal 3 and the angles α, β, γ formed by adjacent sides, and as shown in FIG. The relational expressions of lengths a, b, and c and the relational expressions of angles α, β, and γ are predetermined for each type of crystal system.

  Therefore, first, a relational expression of lengths a, b, c and a relational expression of angles α, β, γ corresponding to the crystal system determined in step ST3 is selected from the table of FIG. For example, in the orthorhombic crystal of this embodiment, the relational expression of lengths a, b, c is a ≠ b ≠ c, and the relational expression of angles α, β, γ is α = β = γ = 90 °. . As a result, the angles α, β, and γ of the lattice constant are determined as 90 °.

  Next, the lattice constant and the plane index are determined based on the layer line H obtained from the first diffraction image 24 and the second diffraction image 25. The plane index represents from which crystal plane the diffraction spot P is reflected, and is represented by (hkl) (see FIG. 10). Here, FIGS. 5 and 6 will be described as a first diffraction image 24 and a second diffraction image 25, respectively. First, since the length b of the lattice constant shown in FIG. 2 is the length in the χ3 axis direction, the interval between the layer lines H adjacent in the lateral direction (χ3 axis direction) in the first diffraction image 24 of FIG. It is determined as the length b of the lattice constant. Further, since the length a of the lattice constant shown in FIG. 2 is the length in the χ1 axis direction, the interval between the layer lines H adjacent in the χ1 axis direction in the second diffraction image 25 of FIG. Determine as a. Then, based on the obtained lengths a and b, indexing of the diffraction spots of the two diffraction images 24 and 25 in FIGS. 5 and 6 is performed. By adjusting the length c of the lattice constant so that indexing can be performed best, all the lengths of a, b, and c can be obtained.

In FIG. 7, when the plane index and lattice constant of the microcrystal 3 are determined in step ST4, the space group of the microcrystal 3 is then determined (step ST5). As shown in FIG. 9, the space group of the microcrystal 3 is predetermined for each crystal system, and is divided into a plurality of space groups in each crystal system. For example, in the orthorhombic crystal of this embodiment, the space group is divided into three types: 16-24, 25-46, and 47-74. In the diffraction spot P, the extinction rule is determined by the space group. The extinction rule is a regularity in which a diffraction spot that should appear in a diffraction image according to a crystal system periodically disappears. Therefore, the space group can be determined by narrowing down from the extinction rule of the diffraction spot.
In the present embodiment, the above-described steps ST3 to ST5 are the first determination steps for determining the crystal system, lattice constant, plane index, and space group of the microcrystal 3 respectively. The order of these steps ST3 to ST5 may be changed.

  In FIG. 7, when the plane index and space group of the microcrystal 3 are determined in step ST5, the diffraction intensity of the diffraction spot P at each plane index is then determined (second determination step, step ST6). Specifically, after a peripheral portion including each diffraction spot P in the first diffraction image 24 and the second diffraction image 25 is read as image data by a computer (not shown), the well-known intensity stored in the computer is stored. The diffraction intensity is determined by the calculation program processing the image data.

  Next, an analysis process is performed based on the determined diffraction intensity of each diffraction spot P (analysis process, step ST7). Specifically, an arithmetic process using Fourier synthesis, a least square method, or the like is performed using the diffraction intensity data of each diffraction spot P and the lattice constant by a computer program.

  FIG. 10 is a table showing calculated values and actually measured values of diffraction intensities at the respective plane indices of the first diffraction image 24 and the second diffraction image 25. FIG. 11 is a bar graph comparing the calculated values of the respective diffraction intensities shown in FIG. 10 with the measured values. In FIG. 11, white bars indicate calculated values of diffraction intensity, and black bars indicate actual measured values of diffraction intensity. The calculated value of diffraction intensity is a value obtained by structural analysis on a computer. On the other hand, the measured value of the diffraction intensity is a value obtained experimentally using the microcrystal structure analysis method of the present embodiment. As shown in FIG. 11, the actually measured values of the respective diffraction intensities show values that are substantially close to the corresponding calculated values of the diffraction intensities, and good analysis results can be obtained by using the analysis method of the present embodiment. I understand.

As described above, according to the microcrystal structure analysis apparatus 1 and the microcrystal structure analysis method of the present embodiment, the X-rays irradiated while the sample container 2 in which the microcrystals 3 are suspended are rotated with respect to the magnetic field generator 13. Based on the first diffraction image 24 of R and the second diffraction image 25 of X-ray R irradiated with the sample container 2 being rotated with respect to the magnetic field generator 13, the structure analysis of the microcrystal 3 is performed. This eliminates the need for an X-ray shielding device for shielding and allowing X-ray irradiation while rotating the sample as in the prior art, and allows structural analysis of microcrystals with a simple configuration.
Further, in the conventional analysis method, since a diffraction image is detected when a specific part is directed in a desired direction while rotating the sample, at least three diffraction images when the sample is rotated by a predetermined angle are detected. In contrast, in the present embodiment, since the structural analysis of the microcrystal 3 can be performed with only the two diffraction images 24 and 25, the measurement time and the analysis time can be shortened.

In the first determination step of the microcrystal structure analysis method, the crystal system of the microcrystal 3 is determined based on the diffraction spot P and the layer line H obtained from the first diffraction image 24 and the second diffraction image 25. The crystal system of crystal 3 can be easily determined.
In the first determination step of the microcrystal structure analysis method, the lattice constant of the microcrystal 3 is determined based on the diffraction spot P and the layer line H obtained from the first diffraction image 24 and the second diffraction image 25. The lattice constant of the crystal 3 can be easily determined.
In the first determination step of the microcrystal structure analysis method, the space group of the microcrystal 3 is determined based on the extinction rule obtained from the first diffraction image 24 and the second diffraction image 25. Can be easily determined.

  In the second determination step of the microcrystal structure analysis method, the diffraction intensity of the diffraction spot P at each plane index is determined based on the image data of the peripheral portion including the diffraction spot P in the first diffraction image 24 and the second diffraction image 25. Therefore, the diffraction intensity of the diffraction spot P at each surface index can be easily determined.

  The present invention is not limited to the above-described embodiment, and can be implemented with appropriate modifications. For example, although the magnetic field generation unit 13 in the above embodiment uses the permanent magnets 13a and 13b, an element such as an electromagnet that generates a magnetic field may be used. Moreover, in the said embodiment, although the magnetic field generation | occurrence | production part 13 was demonstrated as a generation | occurrence | production part of this invention, the electric field generation | occurrence | production part which generate | occur | produces an electric field is good also as a generation | occurrence | production part of this invention.

  In the above embodiment, both the first diffraction image 24 and the second diffraction image 25 are used to determine the crystal system, lattice constant, plane index, and space group of the microcrystal, but either one of them is used. You may decide based on only. Moreover, although the microcrystal structure analysis apparatus 1 in the said embodiment uses the X-ray source which irradiates X-rays as a radiation source, you may use the neutron source which irradiates a neutron beam.

DESCRIPTION OF SYMBOLS 1 Microcrystal structure analyzer 2 Sample container 3 Microcrystal 13 Magnetic field generator (generator)
14 Sample drive unit 21 X-ray source (radiation source)
23 Diffraction image detector 24 First diffraction image 25 Second diffraction image H Layer line P Diffraction spot R X-ray (radiation)

Claims (4)

A first detection step of detecting a first diffraction image of radiation irradiated to the sample in a state in which the sample in which the microcrystals are suspended is rotated at a constant speed with respect to a magnetic field or an electric field;
A second detection step of detecting a second diffraction image of radiation applied to the sample in a state where the sample is rotated with respect to a magnetic field or an electric field;
A first determination step of determining a crystal system, a lattice constant, a plane index, and a space group of the microcrystal based on at least one of the detected first diffraction image and second diffraction image,
A second determination step of determining a diffraction intensity of a diffraction spot at each determined plane index based on the at least one diffraction image;
An analysis step of performing an analysis process based on the determined diffraction intensity;
A microcrystalline structure analysis method comprising:   The microcrystal structure analysis method according to claim 1, wherein, in the first determination step, the crystal system is determined based on a diffraction spot and a layer line obtained from the at least one diffraction image.   The microcrystal structure analysis method according to claim 1 or 2, wherein in the first determination step, the lattice constant is determined based on a layer line obtained from the at least one diffraction image. A magnetic or electric field generator;
A sample driving unit capable of rotating the sample at a constant speed in a state where a magnetic field or an electric field is applied to the sample in which the microcrystals are suspended;
A radiation source capable of irradiating the sample with radiation in a state where the sample is rotated by the sample driving unit and in a state where the sample is stopped from rotating,
Diffraction capable of detecting at least one diffraction image of the first diffraction image of the radiation irradiated to the sample in the rotated state and the second diffraction image of the radiation irradiated to the sample in the rotation stopped state An image detector;
A microcrystalline structure analyzing apparatus comprising: