JP2013068505A - X-ray waveguide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray waveguide capable of forming X-rays with a large spatial range of spatial coherence and capable of modulating the X-ray waveguide characteristics by an external operation.
A core composed of a periodic structure, a cladding formed outside the core, a gap provided between at least a part of the cladding and the core, and at least one of the cladding. Driving means for changing the gap interval by driving the core or the core, and the total reflection critical angle of X-rays at the interface between the cladding and the gap corresponds to the structural period of the core An X-ray waveguide having a total reflection critical angle smaller than the Bragg angle, which is larger than the Bragg angle and has an interface of a plurality of components having different real refractive indices forming the core periodic structure.
[Selection] Figure 1

Description

  The present invention relates to an X-ray waveguide that guides X-rays, and more particularly to an X-ray waveguide that uses a periodic structure as a core.

When dealing with electromagnetic waves with short wavelengths of several tens of nanometers or less, the difference in refractive index with respect to electromagnetic waves between different substances is as small as 10 ^-4 or less. In order to control such electromagnetic waves, large spatial optical systems have been used and are still mainstream. As a main part constituting the spatial optical system, there is a multilayer film reflecting mirror in which materials having different refractive indexes are alternately laminated, and plays various roles such as beam shaping, spot size conversion, wavelength selection and the like.

  In recent years, research has been conducted on X-ray waveguides that confine electromagnetic waves in a core surrounded by a clad and propagate them in order to reduce the size and increase the performance of the optical systems, which are the mainstream. ing. Specifically, a thin-film waveguide having a one-dimensional structure in which a cladding layer sandwiches a core layer (see Non-Patent Document 1), or an X-ray waveguide having a two-dimensional confinement structure in which a fiber-like core is penetrated in a cladding material ( Studies such as Non-Patent Document 2) have been conducted.

Salditt, T .; Kru.ger, S., et al. P. Fuhse, C .; & Ba ... htz, C.I. High-transmission planar x-ray waveguides. Physical Review Letters 100 (2008). Jarre, A .; et al. Two-Dimensional Hard X-Ray Beam Compression by Combined Focusing and Waveguide Optics. Two-Dimensional Hard X-Ray Beam Compression by Combined Focusing and Waveguide Optics. Physical Review Letters 94 (2005).

  However, the conventional X-ray waveguide has a problem to be improved.

  In both Non-Patent Document 1 and Non-Patent Document 2, in order to reduce the X-ray waveguide loss, the 0th-order mode having the smallest propagation angle among the waveguide modes is mainly used. In an X-ray band electromagnetic wave, the refractive index difference (real part) between materials is extremely small, so that the propagation angle of the 0th-order mode is small, and as a result, it is necessary to produce a very small core in the X-ray waveguide. . Therefore, the area of X-rays to be propagated is reduced, the X-ray beam emitted from the X-ray waveguide is small, and the spatial range of spatial coherence, which is one of the features of the waveguide, is limited. Furthermore, in the case of an X-ray waveguide having a two-dimensional confinement structure as in Non-Patent Document 2, it is very difficult to produce a required core having a size of about several tens of nm.

  Furthermore, these X-ray waveguides only exhibit certain X-ray waveguide characteristics determined by the waveguide configuration such as the size of the core cross-section and the material of the cladding and the core. The characteristics could not be modulated by external operation.

  The present invention has been made in view of such background art, and can form X-rays having a large spatial range of spatial coherence, and modulates the X-ray waveguide characteristics by an external operation. A possible X-ray waveguide is provided.

  An X-ray waveguide that solves the above-described problems is formed on a core composed of a periodic structure in which a plurality of basic structures made of materials having different real parts of refractive index are periodically arranged, and on the outside of the core. Further, the clad for confining X-rays in the core by total reflection, a gap provided between at least a part of the clad and the core, driving at least a part of the clad or the core, Drive means for changing the gap interval, and the X-ray total reflection critical angle at the interface between the cladding and the gap is larger than the Bragg angle corresponding to the structure period of the core, and the period of the core The total reflection critical angle at the interface of a plurality of components having different real parts of the refractive index forming the structure is smaller than the Bragg angle.

  According to the present invention, it is possible to provide an X-ray waveguide capable of forming X-rays having a large spatial range of spatial coherence and capable of modulating the X-ray waveguide characteristics by an external operation. .

It is the schematic which shows one embodiment of the X-ray waveguide of this invention. It is a figure which shows X-ray electric field strength distribution in the periodic structure body of a X-ray waveguide. It is a figure which shows the X-ray electric field intensity distribution of an X-ray waveguide, and the cycle number dependence of a propagation loss. It is a figure which shows the space | interval dependence of the gap of the electric field strength distribution of the X-ray waveguide of this invention. It is the schematic which shows the drive means to change the space | interval of the gap between a core and a clad. It is a figure which shows the change of the waveguide X-ray intensity of Example 1, 2 of this invention.

  Hereinafter, the present invention will be described in detail.

  The X-ray waveguide according to the present invention is formed on the outer side of the core composed of a periodic structure in which a plurality of basic structures made of different materials of the refractive index are periodically arranged. A clad for confining X-rays in the core by total reflection, a gap provided between at least a part of the clad and the core, driving at least a part of the clad or the core; Driving means for changing the interval, wherein the critical angle of total reflection of X-rays at the interface between the cladding and the gap is larger than the Bragg angle corresponding to the structural period of the core, and the periodic structure of the core The total reflection critical angle at the interface of a plurality of components having different real parts of the refractive index is smaller than the Bragg angle.

  FIG. 1 is a schematic view showing an embodiment of the X-ray waveguide of the present invention. In FIG. 1, the X-ray waveguide of the present invention includes a core 101, clads 102 and 103 formed outside the core 101, and a gap 104 provided between the clad 102 and the core 101. Driving means 105 for changing the interval L of the gap 104 by driving the clad 102.

  In the present invention, the driving means 105 changes the gap interval by driving at least a part of the clad or by driving a part other than at least a part of the clad and the core integrally. It is characterized by.

  The X-ray waveguide of the present invention is an X-ray waveguide that can utilize a waveguide mode that resonates with the periodicity of the periodic structure by using a periodic structure for the core 101. A gap 104 is arranged at the interface between the clads 102 and 103 and the core 101, and further, an X-ray waveguide characteristic such as the waveguide X-ray intensity of the X-ray waveguide is driven by a driving means 105 that changes the gap L. Sex can be modulated.

  FIG. 1A is a diagram showing an embodiment using a driving means 105 that drives only the clad 102. FIG. 1B is a diagram showing an embodiment using a driving unit 105 that drives the clad 103 and the core 101 integrally. In any case, the gap L of the gap 104 can be adjusted by driving the driving means 105 up and down in the H direction. The clad 102 to be driven (example in FIG. 1A) or a combination of the clad 103 and the core 101 (example in FIG. 1B) is in close contact with the driving means 105. The drive unit 105 includes a drive stage unit 106 that is in close contact with the drive target and a control unit 107 that controls the drive.

(X-ray)
In the present invention, X-rays are electromagnetic waves in a wavelength band where the real part of the refractive index of a substance is 1 or less. Specifically, in the present invention, the X-ray refers to an electromagnetic wave having a wavelength of 100 nm or less including extreme ultraviolet light (Extreme Ultra Violet (EUV) light). Unlike the frequency band of electromagnetic waves (visible light and infrared rays) having a wavelength longer than the wavelength of ultraviolet light, the X-rays are different because the outermost electrons of a substance are extremely high and cannot respond to such short-wavelength electromagnetic wave frequencies. It is known that the real part of the refractive index of a substance is smaller than 1. The refractive index n of a substance for such X-rays is generally expressed by the following formula (1)

The amount of deviation δ from 1 in the real part and the imaginary part related to absorption

It is expressed using Generally unless the atomic energy inherent absorption edge contributes, [delta] will be the real part of the larger material as the refractive index of the electron density is proportional to the electron density [rho _e materials is reduced. The real part of the refractive index is

It becomes. Furthermore, ρ _e is proportional to the atomic density ρ _a and the atomic number Z. As described above, the refractive index of a substance with respect to X-rays is represented by a complex number. In this specification, the real part is referred to as the real part of the refractive index or the real part of the refractive index, and the imaginary part is the imaginary part of the refractive index or the refractive index. Called the imaginary part. In the X-ray band, the substance whose refractive index real part is 1 at maximum is a vacuum, and a gas typified by air has almost the same refractive index as that of vacuum, but the refractive index of almost all substances other than gas is real. The part has a value smaller than 1. In the present specification, the terms “component”, “material”, and “substance” also apply to gases such as vacuum and air.

(Relationship between core and clad)
The X-ray waveguide of the present invention guides the X-ray by confining the X-ray in the core by total reflection at the interface between the core and the clad. In order to realize this total reflection, in the X-ray waveguide of the present invention, the real part of the refractive index of the core at the interface between the core and the clad is larger than the real part of the refractive index of the clad. The critical angle for total reflection at this time is expressed as θ _c as an angle from the interface.

(core)
The X-ray waveguide of the present invention is characterized by using a periodic structure made of a plurality of substances having different real parts of the refractive index for the core. Since the core has a periodic structure, the waveguide mode formed in the waveguide resonates with the periodic structure. Such a periodic structure of different real part of the refractive index, when the number of periods is infinite, forms a photonic band between the propagation constant and the angular frequency of the X-ray and has a specific mode that resonates with the periodicity of the core. Only X-rays can exist in this structure. It is preferable that at least one substance among the plurality of substances having different real parts of refractive index is an oxide.

  The periodic structure is a structure in which basic structures are periodically arranged, a one-dimensional periodic structure in which they are stacked with a layered structure as a basic structure, and a two-dimensional periodic structure in which they are arranged with a cylindrical structure as a basic structure A three-dimensional periodic structure in which the cage structure is arranged as a basic structure can be exemplified. The waveguide mode formed in the X-ray waveguide according to the present invention is caused by multiple reflection corresponding to each dimension of the periodic structure of the periodic structure. Such a mode is formed by periodicity, and the positions of the antinodes and nodes of the X-ray electric field distribution and electric field intensity distribution coincide with the positions in the respective substance regions constituting the basic structure. At that time, the propagation loss of the waveguide mode in which the electric field intensity of the X-ray is concentrated on the substance having a low electron density of the periodic structure is smaller than that of other waveguide modes, and the waveguide mode is selectively extracted. It becomes possible.

  In FIG. 2, a cylindrical air hole 201 extending in one direction in the silica 202 has a two-dimensional triangular lattice structure in a direction (xy in-plane direction) perpendicular to the hole length direction (z direction in the figure). The example of the electric field intensity distribution of the X-ray in the periodic structure which forms is shown. In FIG. 2, the broken line represents the structural period d, and the black and white shading in the cylindrical air hole 201 represents the electric field intensity of the X-ray, and for one of the guided modes formed in this material. Electric field intensity distribution. Black and white correspond to large and small electric field strengths, respectively. The electric field strength is explained by the intervals of a large number of circles instead of black and white. The size of the space between the multiple circles in the cylindrical air hole 201 represents the electric field strength 205 of the X-ray, which is the electric field strength distribution for one of the guided modes formed in this material. A small interval between many circles corresponds to a large electric field strength, and a large interval corresponds to a small electric field strength. The center portion of the air hole 201 has a small circle interval and a high electric field strength 205, and the circle interval changes from the center portion toward the periphery of the hole so that the circle interval increases. The interval is large and the electric field strength is weak. The regions where the electric field intensity is maximized and minimized are periodically repeated in the x direction and the y direction, and the electric field is concentrated in the holes of the periodic structure (the basic structure 205 of the periodic structure). The air hole 101 represents the basic structure of the periodic structure. 204 represents the periodic direction.

(Containment relationship)
By confining the X-ray having the electric field intensity distribution resonating with such a periodic structure in the core by the clad, it is possible to guide the X-ray by forming a waveguide mode that resonates with the periodicity. This guided mode is referred to as a periodic resonant guided mode. On the other hand, the core of the X-ray waveguide according to the present invention is not an infinite periodic structure, but a periodic structure having a finite thickness sandwiched between clads. There is a waveguide mode in the case of a uniform medium having an average refractive index, and this is referred to as a uniform waveguide mode.

  In contrast to this uniform waveguide mode, the periodic resonant waveguide mode in which the X-ray waveguide of the present invention appears has less loss than the adjacent uniform waveguide mode, and has a uniform phase. The X-ray waveguide of the present invention is designed to satisfy the following conditions in order to form the above-described periodic resonant waveguide mode in addition to the uniform waveguide mode by total reflection at the interface between the cladding and the core ( (See FIG. 1).

In FIG. 1, when the real part of the refractive index of the clad material at the interface between the clad and the core is n _clad and the real part of the refractive index of the material on the core side is n _core , the total from the direction parallel to the film surface is shown. The reflection critical angle θ _c-total (°) is expressed by the equation (2) where n _clad <n _core.

It is expressed.

Further, when the structural period of the periodic structure forming the core is d (203 in FIG. 2), the Bragg angle θ _B (°) is defined as in the following equation (3) regardless of the presence or absence of multiple diffraction in the core. To do.

m is the order (natural number), and λ is the wavelength of the X-ray. The physical property parameter of the substance constituting the X-ray waveguide of the present invention, the structural parameter of the waveguide, and the wavelength of the X-ray must satisfy θ _B <θ _c-total .

  In the present invention, it is necessary to satisfy another condition, which will be described below. When the periodic structure is composed of a plurality of components having different real parts of the refractive index, it is necessary to consider X-ray reflection at the interface between the components. In order for the X-ray waveguide of the present invention to function, multiple reflections originating from the periodic structure must occur. When total reflection occurs at the interface of the material constituting the periodic structure, for example, for a one-dimensional periodic structure, X-rays are confined in the component having the highest refractive index among the materials forming the laminated structure, As a result of the multiple interference being inhibited, the object of the present invention cannot be achieved. In other words, the unit constituting the periodic structure functions as a multi-total reflection X-ray waveguide, resulting in the same structure as a conventional flat plate waveguide. Therefore, it is necessary that the total reflection critical angle at the interface between components having different real parts of the refractive index forming the periodic structure of the core is smaller than the Bragg angle. This can be expressed as follows using mathematical formulas.

When the total reflection critical angle between different components of the real part of the refractive index constituting the periodic structure of the core is θ _c-multi (°), the equation θ _c-multi <θ _B is satisfied.

  When the conditions described above are satisfied, the waveguide mode confined by total reflection at the interface between the clad and the core can be localized in the core. Effective propagation angle measured from the direction parallel to the membrane

Is represented by the following equation using a wave number vector (propagation constant) k _z in the propagation direction of the waveguide mode and a wave number vector k ₀ in vacuum.

  As described above, in the X-ray waveguide of the present invention, only the waveguide mode X-rays that resonate with the period of the regular structure due to multiple interference can be selectively propagated with low loss. The x-rays are in phase throughout the core thickness. That is, it becomes a spatially coherent X-ray, and is emitted from the end face of the waveguide with a small divergence angle determined by the wavelength of the X-ray and the structure period of the core.

Since the periodic resonant waveguide mode has a smaller loss than the adjacent uniform waveguide mode, the mode-selected X-ray can be guided. FIG. 3 is a diagram showing the period dependence of the X-ray electric field intensity distribution and propagation loss of the X-ray waveguide. FIG. 3A is a schematic diagram of an X-ray waveguide in which a one-dimensional periodic structure having a layered structure of silica 302 and a surfactant 303 as a basic structure is cored and a clad is gold 301. FIG. 3B shows a waveguide in which a one-dimensional periodic structure having a layered structure of silica and a surfactant as a basic structure is cored and the clad is gold (FIG. 3A, structure period d = 10 nm). 3 is a result of a simulation experiment by a finite element method of an electric field intensity distribution in the core of the periodic resonant waveguide mode of (X-ray energy: 17.5 keV). In this waveguide, in an X-ray of 17.5 keV, θ _c-total = 0.243 °, θ _B = 0.203 °, and θ _c-multi = 0.058 °, and θ _B <θ _c-total And θ _c-multi <θ _B.

  The propagation angle of this guided mode is slightly smaller than the Bragg angle of the periodic structure, and the electric field is concentrated near the center of the core. . As shown in FIG. 3C, the advantage of these periodic resonant waveguide modes is that the effect becomes more prominent and the propagation loss decreases as the number of periods increases. The number of periods of the periodic structure that is the core of the X-ray waveguide of the present invention is preferably 20 periods or more.

  Even if the dimension of the X-ray waveguide of the present invention for confining X-rays is a one-dimensional structure in which a film-like core is sandwiched between clads, a core whose cross section perpendicular to the waveguide direction is a circle or a rectangle is used. It may be two-dimensionally surrounded by a clad. In the two-dimensional confinement type waveguide, X-rays are confined two-dimensionally in the waveguide, so that the divergence is suppressed compared to the one-dimensional confinement type, and an X-ray beam having a small beam size can be extracted. When the periodic structure is the above-described two-dimensional structure (basic structure: cylindrical structure) or three-dimensional structure (basic structure: cage structure), the electric field intensity that resonates with a plurality of periodic structures in the periodic direction. A distribution can be formed more efficiently in the core.

(Clad material)
The total reflection critical angle θ _c− from the direction parallel to the film surface when the real part of the refractive index of the clad side material at the interface between the clad and the core is n _clad and the real part of the refractive index on the core side is n _{core. The total} (°) is expressed by Expression (2) as n _clad <n _core . The clad material of the X-ray waveguide of the present invention can be configured by other structural parameters and physical property parameters of the waveguide satisfying the formula (2). For example, when a mesoporous silica having a two-dimensional periodic structure in which holes are arranged in a triangular lattice shape with a structure period of 10 nm is used as the core, the cladding can be made of Au, W, Ta, or the like.

  By adopting such a configuration, the X-ray waveguide of the present invention can resonate with periodicity, phase-control, form a periodic resonant waveguide mode with little loss, and guide X-rays.

(Gap, relationship with periodic structure, thickness)
The X-ray waveguide according to the present invention is characterized in that a gap is disposed between a periodic structure as a core and a clad. The gap is filled with fluid or is vacuum. The gap is composed of a fluid, that is, a gas or a liquid so that the distance can be changed. For example, a gas such as air, nitrogen, helium, or argon, or a liquid such as water or alcohol can be used. In the present invention, it is preferable to use a gas that is a fluid with a low electron density so that absorption and scattering of X-rays by the substance of the fluid in the gap can be relatively suppressed, and a gas such as air, nitrogen, and helium, or a vacuum is used. More preferably, it is used.

  As described above, as shown in FIG. 3, when there is no gap, the electric field intensity distribution of the X-ray is concentrated at the center of the core, and the loss due to the leakage of the electric field to the cladding part is small, that is, the mode is close. In comparison, a waveguide mode with a smaller propagation loss is formed.

FIG. 4 is a diagram showing the gap dependence of the electric field intensity distribution of the X-ray waveguide of the present invention. FIG. 4A shows a gap 402 made of air between the core of an X-ray waveguide using a multilayered periodic structure (structure period: 10 nm) of silica 403 and surfactant 404 and the cladding of tungsten 401. It is the schematic of the X-ray waveguide of the structure which arranged. The results of a simulation experiment (X-ray energy: 8.04 keV) of the X-ray waveguide of FIG. 4A by the finite element method are shown in FIG. 4B: gap 0 nm, FIG. 4C: gap 4 nm, and FIG. 4 (d): shows a gap of 8 nm. In this waveguide, in an X-ray of 8.04 keV, θ _c-total = 0.515 °, θ _B = 0.442 ° and θ _c-multi = 0.128 °, and θ _B <θ _c-total And θ _c-multi <θ _B.

  In FIG. 4, the upper end of the gap is at the coordinate y = −200 nm. As shown in FIG. 4C with a gap of 4 nm, it can be seen that the X-ray electric field intensity distribution in the periodic resonance waveguide mode changes compared to the case without the gap (FIG. 4B). When the gap interval is 4 nm, the electric field intensity distribution concentrated at the center of the core is concentrated at the gap, and the X-ray oozes out to the clad and propagation loss is larger than that of other adjacent modes. Increase. That is, it means that the periodic resonant waveguide mode is not selectively transmitted.

  On the other hand, when the gap interval in FIG. 4D is changed to 8 nm, the electric field strength is concentrated at the core center as in the case where there is no gap, and the propagation loss of the waveguide mode peculiar to periodicity is reduced. Smaller than other adjacent guided modes. As a result of the simulation experiment, it can be seen that the propagation loss of the periodic resonant waveguide mode changes periodically with respect to the gap interval.

  If the gap interval becomes too large, the waveguide characteristics of the periodic resonance waveguide mode will not be noticeable, and the loss of the guided X-ray will increase. Therefore, the gap interval is 100 nm or less, preferably 50 nm or less. Is desirable.

  FIG. 5 is a schematic diagram showing driving means for changing the gap distance between the core and the clad. The X-ray waveguide of FIG. 5 is a diagram depicting FIG. 1A in more detail. An X-ray waveguide having a clad 502 to be driven, a fixed core 501 and a clad 503, and a gap 504 formed between the core 501 and the clad 502. As shown in FIG. 5, the driving means for changing the gap interval according to the present invention does not have to be a single driving direction, and driving means 505 capable of driving in a plurality of directions can be used. The driving means 505 generally includes a driving stage unit 506 that is in close contact with a clad 502 that is a driving target, and a control unit 507 thereof. Moreover, as long as it contributes to the modulation of the periodic resonant waveguide mode, the driving direction can be arbitrarily selected. In FIG. 5, in order to change the gap interval, the z-axis is mainly changed. However, if angle adjustment with respect to the X-ray waveguide direction (y-axis) is necessary, correction is made with the ω-axis. Can do. On the other hand, the characteristics of the X-ray waveguide of the present invention, such as the X-ray radio wave intensity distribution, in the X-ray propagation direction are also affected by the change in the angle of the clad 501 with respect to the X-ray waveguide direction by scanning the ω axis. Since it gradually changes as it goes to, modulation of the waveguide mode characteristics can be performed.

  FIG. 5 shows an example in which only the clad 502 is driven. However, in the present invention, it is only necessary to drive a part of the clad to change the gap interval. As shown in FIG. The case where both are integrally driven while the part and the core are coupled is also included.

  In the present invention, a piezo actuator is preferably used as the driving means for changing the gap between the core and the clad because position control and accuracy with high resolution are required.

(Material for periodic structures)
The periodic structure used for the core of the X-ray waveguide of the present invention is not particularly limited as long as it satisfies the above-described configuration of the waveguide of the present invention. A multilayer film produced by sputtering or vapor deposition, a periodic structure produced by a conventional semiconductor process such as photolithography, electron beam lithography, etching process, lamination, bonding, or the like can be used. In addition, oxidation degradation can be prevented by using an oxide as a material constituting the periodic structure.

  Since the difference in the refractive index of the core material contributes to the gap dependence of the modulation of the waveguide mode, the refractive index of the core material can be appropriately selected according to the required waveguide characteristics. .

  As the core of the X-ray waveguide of the present invention, an organic-inorganic multilayer film or a mesoporous material film can be preferably used particularly from the viewpoint of the simplicity of the manufacturing process and the periodic structure with high regularity. The porous material is classified according to its pore diameter by IUPAC (International Union of Pure and Applied Chemistry), and the porous material having a pore diameter of 2 to 50 nm is classified as a mesoporous material film. These materials are characterized in that a periodic structure is formed in a self-assembled manner by applying a reaction liquid, which is mainly a precursor of an oxide, to the substrate by a process such as coating. Therefore, many processes of the conventional semiconductor process are not required, and it is possible to fabricate with extremely simple and high throughput. It is extremely difficult to form a periodic structure of several tens of nanometers by a conventional semiconductor process, and it can be said that it is almost impossible to manufacture a periodic structure of two or more dimensions.

The periodic structure used in the present invention forms a periodic structure by an inorganic component and an organic component (or pores) of an organic-inorganic multilayer film or a mesoporous material film. An inorganic oxide is preferably used as the inorganic substance, and examples thereof include silica, titanium oxide, and zirconium oxide. Examples of the organic substance include an amphiphilic molecule represented by a surfactant, an alkyl chain portion of a siloxane oligomer, or an alkyl chain portion of a silane coupling agent. As the surfactant, C ₁₂ H ₂₅ (OCH ₂ CH ₂ ) ₄ OH, C ₁₆ H ₃₅ (OCH ₂ CH ₂ ) ₁₀ OH, C ₁₈ H ₃₇ (OCH ₂ CH ₂ ) ₁₀ OH, Tween 60 (Tokyo Kasei) Industrial), Pluronic L121 (BASF), Pluronic P123 (BASF), Pluronic P65 (BASF), Pluronic P85 (BASF), etc., and a periodic structure by appropriately selecting them It is possible to adjust the dimension of the periodic structure and the structure period (surface spacing obtained from Bragg diffraction). Table 1 shows the structure of the periodic structure for the organic matter used.

  In the case of a mesoporous material film, when it is formed by self-assembly by application of a precursor reaction solution, organic substances remain contained in the pores. These organic components can be removed by a conventionally known method such as baking, extraction with an organic solvent, or ozone oxidation treatment. In the present invention, the organic component may remain in the pores of the mesoporous material film as long as it has the required performance. However, by removing the organic component, the X-ray absorption component is reduced. Therefore, an X-ray waveguide with smaller propagation loss can be provided. However, the higher the organic component remaining rate, the better the structural periodicity of the mesoporous material film is often, and the characteristics of the periodic resonant waveguide mode can be obtained relatively clearly. Therefore, the residual rate (removal rate) of the organic component can be appropriately determined according to the target waveguide characteristics.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
This example is an example of an X-ray waveguide using tungsten as a clad, a multilayer film composed of B ₄ C and Al ₂ O _{3 as} a core, and a vacuum as a gap.

  The manufacturing method of the X-ray waveguide of the present embodiment includes the following steps by sputtering. The example of the X-ray waveguide shown in FIG. 5 is shown.

(A) Formation of Cladding Layer Tungsten 503 is formed with a thickness of 30 nm on a Si substrate (C in FIG. 5) by magnetron sputtering.

(B) Formation of multilayer film (501 in FIG. 5)
A multilayer film is formed by alternately forming films of Al ₂ O ₃ (A in FIG. 5) and B ₄ C (B in FIG. 5) by magnetron sputtering. The thicknesses of Al ₂ O ₃ and B ₄ C are 2.0 nm and 13.0 nm, respectively, and the lowermost and uppermost layers of the multilayer film are Al ₂ O ₃ . Al ₂ O ₃ and B ₄ C are formed as 101 layers and 100 layers, respectively.

(C) Determination of waveguide length The multilayer film formed on the Si substrate is cut together with the Si substrate by using a dicing apparatus so that the waveguide length becomes 1 mm.

(D) Arrangement of clad having driving means A 30 nm tungsten film (clad 502) formed by magnetron sputtering is arranged on a glass substrate 506 cut to a length of 1 mm so as to face the surface of the multilayer film. The position of the tungsten film substrate can be controlled by a piezo actuator 505 having a drive shaft shown in FIG.

The obtained X-ray waveguide has a shape in which the core is sandwiched between clads, and the X-rays are confined in the core by total reflection at the interface between the core and the clad. According to this configuration, the relationship between the period of the multilayer film as the core and the real part of the refractive index of the material forming the core satisfies θ _B <θ _c-total and θ _c-multi <θ _B. For example, for an X-ray of 8.04 keV, θ _c-total = 0.472 ° (total reflection critical angle at the interface between Al ₂ O ₃ and tungsten), θ _B = 0.295 °, and θ _c-multi = 0.182 ° (total reflection critical angle at the interface between Al ₂ O ₃ and B ₄ C), and X-rays are confined in the core by total reflection at the interface between the cladding and the core, and the periodic resonant waveguide mode is Can be formed.

  An X-ray (energy: 8.04 keV) is incident from the end of the X-ray waveguide, and an output X-ray emitted from the end of the waveguide forms an interference pattern behind the waveguide (camera length: 1500 mm). Measure with an X-ray two-dimensional detector. The measurement system is evacuated to a vacuum state.

  FIG. 6A shows a change in the transmittance of the X-ray waveguide of this embodiment when the gap 504 is changed. As the gap interval increases, the transmittance periodically increases and decreases, confirming that the X-ray waveguide characteristics can be modulated by the gap interval. Even if the ω-axis in FIG. 5 is driven in a range of ± 0.0002 °, the same change in the X-ray waveguide intensity can be observed.

  Even if the clad 502 is fixed and the clad 503, the Si substrate (C in FIG. 5), and the core 501 formed of a multilayer film are integrally driven by a piezoelectric actuator, the gap 504 is changed to change the gap 504 in FIG. The same waveguide characteristics can be observed.

(Example 2)
This embodiment is an example of an X-ray waveguide in which the cladding is filled with tungsten, the core is filled with mesoporous silica, and the gap is filled with air.

  In this mesoporous material film, vacancies form a two-dimensional periodic structure in a direction (xy in-plane direction) perpendicular to the X-ray waveguide direction. The material other than the pores is mesoporous silica which is silica. A method for producing the X-ray waveguide of this example containing this mesoporous silica will be described below.

(A) Formation of Cladding Layer Tungsten 503 is formed with a thickness of 20 nm on a Si substrate (C in FIG. 5) by magnetron sputtering.

(B) Preparation of precursor solution of mesostructured film A mesoporous silica film is prepared by a dip coating method. The precursor solution of the mesostructure was added to an Erlenmeyer flask in the order of 54.7 mL of tetraethoxysilane, 74.4 mL of ethanol, and 26.4 mL of 0.01 M hydrochloric acid, and after 15 minutes, P123 (BASF), which is a surfactant, was added. Solution) is sufficiently dissolved in 49.6 mL of ethanol. Then, after stirring for 3 hours, 12.0 mL of pure water is added.

(C) Formation of mesostructured film (501 in FIG. 5)
The precursor solution of the mesostructured film (b) is dip-coated on the substrate sputtered with tungsten using a dip coater (pickup speed: 0.5 mm per second). The temperature at this time is 25 ° C., and the relative humidity is 5% or less. After film formation, the film is held in a constant temperature and humidity chamber at 25 ° C. and a relative humidity of 40% for 18 hours or more. Thereafter, P123 (BASF) is removed by solvent extraction using ethanol. FIG. 5 is a simplified plan view, but in FIG. 5, A is silica and B is pores.

(D) Evaluation of mesoporous silica film The prepared mesostructured film is subjected to θ-2θ scanning X-ray diffraction in a Bragg-Brentano configuration. As a result, it is confirmed that this mesostructured film is ordered in the normal direction of the substrate surface, and the structural interval in the plane spacing, that is, the confinement direction, is 10.2 nm. Its film thickness is approximately 480 nm.

(F) Determination of waveguide length The X-ray waveguide is cut using a dicing apparatus so that the waveguide length becomes 1 mm.

(F) Arrangement of clad having driving means A 30 nm tungsten film 502 formed by magnetron sputtering is arranged on a glass substrate cut to a length of 1 mm so as to face the surface of the mesoporous silica film. The position of the tungsten substrate can be controlled by a piezoelectric actuator 505 having a drive shaft shown in FIG.

The mesoporous silica film that is the core of the obtained X-ray waveguide has a period of 10.2 nm, and therefore satisfies θ _B <θ _c-total and θ _c-multi <θ _B. For example, for 8.04 keV X-rays, θ _c-total = 0.515 ° (total reflection critical angle at the interface between silica and tungsten), θ _B = 0.433 °, and θ _c-multi = 0.201. ° (total reflection critical angle at the interface between silica and air), and X-rays are confined in the core by total reflection at the interface between the cladding and the core, and can form a periodic resonant waveguide mode.

  An X-ray is an interference pattern formed by X-rays (energy: 8 keV) incident from the end of the X-ray waveguide and formed by the emitted X-rays emitted from the end of the waveguide behind the waveguide (camera length: 1500 mm). Measure with a two-dimensional detector. The measurement system is at atmospheric pressure.

  FIG. 6B shows a change in the transmittance of the X-ray waveguide of this example when the gap 504 is changed. As the gap interval increases, the transmittance periodically increases and decreases, confirming that the X-ray waveguide characteristics can be modulated by the gap interval. Even when the ω-axis of FIG. 5 is driven ± 0.0002 °, the same change in the X-ray waveguide intensity can be observed.

  Even when the clad 502 is fixed and the clad 503, the Si substrate (C in FIG. 5), and the core 501 made of a mesoporous silica film are driven integrally by a piezoelectric actuator, the gap 504 is changed to change the gap 504 in FIG. ) Can be observed.

  In this example, when the extraction rate of P123 (BASF) at the time of producing the mesoporous silica film is lowered, the intensity of the guided X-ray is reduced, but the characteristics of the periodic resonance waveguide mode and the modulated characteristics thereof. Can be observed more clearly.

  The X-ray waveguide according to the present invention can provide an X-ray beam having a uniform phase, and can further adjust waveguide characteristics such as transmittance, Useful in imaging techniques.

101 core (periodic structure)
DESCRIPTION OF SYMBOLS 102 Cladding 103 Cladding 104 Gap 105 Driving means for changing gap distance 106 Driving stage section of driving means 107 Control section of driving means

Claims (7)

  A core composed of a periodic structure in which a plurality of basic structures made of materials having different real refractive indexes are periodically arranged, and X-rays formed outside the core are confined in the core by total reflection. A clad, a gap provided between at least part of the clad and the core, and driving means for changing the gap interval by driving at least part of the clad or the core. A plurality of X-ray total reflection critical angles at the interface between the cladding and the gap are larger than a Bragg angle corresponding to the core structure period, and the refractive index real parts forming the core periodic structure are different. An X-ray waveguide characterized in that the critical angle for total reflection at the interface of the component is smaller than the Bragg angle.   The X-ray waveguide according to claim 1, wherein the gap is filled with a fluid or is a vacuum.   The driving means is configured to change the gap interval by driving at least a part of the clad or by driving a part other than at least a part of the clad and the core integrally. The X-ray waveguide according to claim 1 or 2.   The X-ray waveguide according to any one of claims 1 to 3, wherein the driving means is a piezo actuator.   The X-ray waveguide according to claim 1, wherein the number of periods of the periodic structure of the core is 20 or more.   6. The X-ray waveguide according to claim 1, wherein the core is an inorganic multilayer film or a mesoporous material film.   7. The X-ray waveguide according to claim 1, wherein at least one of the plurality of substances having different real parts of refractive index is an oxide.

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