JP6521215B2 - Analyzer and electronic device - Google Patents

Description

  The present invention relates to an analyzer and an electronic device.

  In recent years, the demand for medical diagnosis, food inspection, etc. is increasing, and development of a small and high-speed sensing technology is required. Various types of sensors have been considered including electrochemical methods, but Surface Plasmon Resonance (SPR) is used because integration is possible, cost is low and measurement environment is not selected. There is growing interest in sensors that For example, it is known to detect the presence or absence of adsorption of a substance, such as the presence or absence of adsorption of an antigen in an antigen-antibody reaction, using surface plasmons generated on a metal thin film provided on the surface of a total reflection prism.

In addition, methods of detecting the Raman scattering of a substance attached to a sensor site using surface enhanced Raman scattering (SERS) and identifying the attached substance are also studied. SERS is a phenomenon in which Raman scattered light is enhanced by 10 ² to 10 ¹⁴ times on the surface of metal of nanometer scale. When excitation light such as a laser is irradiated in a state where a target substance is adsorbed on this surface, light with a wavelength slightly deviated from the wavelength of the excitation light (Raman scattered light) by the amount of vibrational energy of the substance (molecules) Is scattered. When this scattered light is subjected to spectral processing, a spectrum (fingerprint spectrum) unique to the type of substance (molecular species) is obtained. By analyzing the position and shape of the fingerprint spectrum, it is possible to identify a substance with extremely high sensitivity. Such a sensor desirably has a high degree of enhancement of light based on surface plasmons excited by light irradiation.

  For example, a sensor having a structure that realizes a hybrid mode in which both modes of localized plasmon (LSP: localized surface plasma) and propagating plasmon (PSP: propaged surface plasma) resonate simultaneously for the purpose of higher sensitivity sensing As an example of the element, Non-Patent Document 1 proposes a so-called GSPP (Gap type Surface Plasmon Polariton), which describes the basic matter of electromagnetic coupling of LSP and PSP.

  Furthermore, for the purpose of higher sensitivity sensing, the shape of the metal-metal microstructure is made anisotropic to strengthen the enhanced electric field of the localized surface plasmon (LSP) excited to the metal-metal microstructure. That is being tried. For example, Non-Patent Document 1 reports a metal particle having anisotropy called gold nanorods, and when the aspect ratio (long axis diameter / short axis diameter) of the particle becomes large, the absorption spectrum increases and resonance It is shown that the wavelength shifts to the long wavelength side.

OPTICS LETTERS Vol. 34, No. 3 2009, pp244-246 J. Phys. Chem. B 1999, 103, pp3073-3077

If the method disclosed in the above-mentioned Non-Patent Document 2 is applied to achieve a high degree of electric field enhancement, the aspect ratio of the metal particles will be increased or the metal particles will be sharpened. As a result, since the resonance wavelength is increased (wavelength shift), the sensitivity of the sensor in the practical wavelength range may be reduced. Therefore, in order to achieve a high degree of enhancement at the target wavelength, it is not sufficient to merely change the shape of the metal particles, and it is required to perform more precise dimensional design.

  One of the objects according to some aspects of the present invention is to provide an analysis device and an electronic device capable of obtaining a high degree of enhancement in an enhancement degree spectrum and detecting and analyzing a target substance with high sensitivity. is there.

  The present invention has been made to solve at least a part of the problems described above, and can be realized as the following aspects or application examples.

One aspect of the analyzer according to the present invention is
A metal layer, a light transmitting layer provided on the metal layer and transmitting excitation light, and a second light emitting layer provided on the light transmitting layer, arranged at a first pitch in a first direction, and crossing the first direction An electric field enhancing element comprising a plurality of metal microstructures arranged at a second pitch in a direction;
A light source for irradiating the electric field intensifying element with the linearly polarized light polarized in the first direction as the excitation light;
A detector for detecting light emitted from the electric field enhancing element;
Equipped with
The arrangement of the metal microstructures of the electric field enhancing element satisfies the relationship of the following formula (1),
P1 <P2 ≦ Q + P1 (1)
[Here, P1 is the first pitch, P2 is the second pitch, and Q is the angular frequency of the localized plasmon excited in the row of the metal fine structure ω, and the metal constituting the metal layer The dielectric constant is ε (ω), the dielectric constant around the metal microstructure is ε, the speed of light in vacuum is c, the irradiation angle of the excitation light is θ, and the inclination angle from the thickness direction of the metal layer is θ, Represents the pitch of the diffraction grating that satisfies the following formula (2).
(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2a.pi. / Q (a =. ± .1 ,. ± .2 ,,) ... (2)]
When the dimensions of the first direction and the second direction of the metal microstructure are d1 and d2, respectively, the relationship of d1> d2 is satisfied.

  Such an analyzer can obtain a very high degree of enhancement in the enhancement spectrum and can detect and analyze the target substance with high sensitivity.

  In the analyzer according to the present invention, the excitation light includes light having a wavelength of 620 nm to 650 nm, and the dimension of the metal fine structure in a third direction intersecting the first direction and the second direction is d3. And the relationship of 1.1 <(d1 / d3) may be satisfied. In this way, a higher degree of electric field enhancement can be obtained.

  In the analyzer according to the present invention, the refractive index of the light transmitting layer may be 1.4 or more and 1.7 or less. In this way, a higher degree of electric field enhancement can be obtained.

  In the analyzer of the present invention, the relationship of d1> d3> d2 may be satisfied. In this way, a higher degree of electric field enhancement can be obtained.

  In the analyzer of the present invention, d3 may be 30 nm or more and 50 nm or less. In this way, a higher degree of electric field enhancement can be obtained.

  In the analyzer of the present invention, the material of the light transmitting layer may be silicon oxide or aluminum oxide. In this way, a higher degree of electric field enhancement can be obtained.

  One aspect of an electronic device according to the present invention is an analysis device described above, a calculation unit that calculates health care information based on detection information from the detector, a storage unit that stores the health care information, and the health And a display unit for displaying medical information.

  According to such an electronic device, the degree of enhancement is extremely large, the target substance can be detected and analyzed with high sensitivity, and highly sensitive and highly accurate health care information can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view which shows the electric field enhancing element of embodiment typically. The schematic diagram which planarly viewed the electric field enhancement element of embodiment from the thickness direction of the metal layer. The schematic diagram of the cross section perpendicular | vertical to the 1st direction of the electric field enhancement element of embodiment. The schematic diagram of a cross section perpendicular | vertical to the 2nd direction of the electric field enhancement element of embodiment. The schematic diagram which planarly viewed the electric field enhancement element of embodiment from the thickness direction of the metal layer. The schematic diagram explaining the shape of metal fine structure. Graph of dispersion relation showing dispersion curves of excitation light and gold. A graph showing the relationship between the dielectric constant of Ag and the wavelength. 6 is a graph showing the dispersion relationship of metal dispersion curves, localized plasmons and excitation light. The schematic diagram of the analyzer which concerns on embodiment. The schematic diagram of the electronic device which concerns on embodiment. Calculation model used in the experimental example. The plot which shows the relationship between the electric field enhancement degree based on an experiment example, and the shape of metal microstructure. The plot which shows the shape of the metal fine structure which concerns on an experiment example. The plot which shows the relationship between the electric field enhancement degree based on an experiment example, and the shape of metal microstructure. The plot which shows the shape of the metal fine structure which concerns on an experiment example. The plot which shows the relationship between the electric field enhancement degree based on an experiment example, and the shape of metal microstructure. The plot which shows the relationship between the electric field enhancement degree based on an experiment example, and the shape of metal microstructure. The plot which shows the relationship between the electric field enhancement degree based on an experiment example, and the shape of metal microstructure. The plot which shows the relationship between the electric field enhancement degree based on an experiment example, and the shape of metal microstructure. The plot which shows the shape of the metal fine structure which concerns on an experiment example.

  Hereinafter, some embodiments of the present invention will be described. The embodiment described below is an example of the present invention. The present invention is not limited to the following embodiments at all, and includes various modifications implemented without departing from the scope of the present invention. Note that not all of the configurations described below are necessarily essential configurations of the present invention.

1. Electric field enhancing element FIG. 1 is a perspective view of an electric field enhancing element 100 according to an example of the embodiment. FIG. 2 is a schematic view of an electric field enhancing element 100 according to an example of the embodiment as viewed in plan (as viewed in the thickness direction of the light transmitting layer). FIG.3 and FIG.4 is a schematic diagram of the cross section of the electric field enhancement element 100 based on an example of embodiment. The electric field enhancing element 100 of the present embodiment includes the metal layer 10, the light transmitting layer 20, and the metal fine structure 40.

1.1. Metal Layer The metal layer 10 is not particularly limited as long as it provides a metal surface, and may be, for example, a thick plate, or may have a film, layer or film shape. The metal layer 10 may be provided, for example, on the substrate 1. The substrate 1 in this case is not particularly limited, but a substrate that hardly affects the propagation surface plasmon excited in the metal layer 10 is preferable. Examples of the substrate 1 include a glass substrate, a silicon substrate, and a resin substrate. The shape of the surface on which the metal layer 10 of the substrate 1 is provided is not particularly limited. When forming a regular structure on the surface of the metal layer 10, the surface corresponding to the regular structure may be provided, or when the surface of the metal layer 10 is flat, it may be flat. In the example of FIGS. 1 to 4, the metal layer 10 is provided on the surface (plane) of the substrate 1.

  Here, although the expression plane is used, such expression does not indicate that the surface is a smooth (smooth) mathematically exact plane without slight unevenness. For example, there may be unevenness on the surface due to atoms making up or unevenness due to secondary structures (crystals, grain agglomerates, grain boundaries, etc.) of the material to be formed, microscopically It may not be a strict plane if it sees. However, even in such a case, when viewed from a more macroscopic viewpoint, these asperities become inconspicuous, and the surface can be observed to such an extent that it can be referred to as a plane. Therefore, in the present specification, if it can be recognized as a plane when viewed from such a macroscopic viewpoint, this is referred to as a plane.

  Further, in the present embodiment, the thickness direction of the metal layer 10 coincides with the thickness direction of the light transmitting layer 20 described later. In the present specification, the thickness direction of the metal layer 10 or the thickness direction of the light transmitting layer 20 may be referred to as a thickness direction, a height direction, a third direction, or the like when the metal microstructure 40 is described. Also, for example, when the metal layer 10 is provided on the surface of the substrate 1, the normal direction of the surface of the substrate 1 may be referred to as a thickness direction, a thickness direction, a height direction, or a third direction.

  Furthermore, viewed from the substrate 1, the direction on the metal layer 10 side may be expressed as upper or upper, and the opposite direction may be expressed as lower or lower. The expression of the upper side and the lower side is used regardless of the direction in which the gravity acts, and the direction of the viewpoint and the line of sight when viewing the element is appropriately defined and expressed. Furthermore, in the present specification, for example, the expression “the member B is provided on the member A” refers to the case where the member B is provided in contact with the member A, the other member or the member A on the member A It is a meaning including the case where the member B is arrange | positioned through space.

  The metal layer 10 can be formed by, for example, a method such as vapor deposition, sputtering, casting, or machining. When the metal layer 10 is provided on the substrate 1, it may be provided on the entire surface of the substrate 1 or on a part of the surface of the substrate 1. The thickness of the metal layer 10 is not particularly limited as long as propagation surface plasmons can be excited near the surface of the metal layer 10 or the interface between the metal layer 10 and the light transmitting layer 20, and for example, 10 nm or more and 1 mm or less, preferably 20 nm The thickness can be 100 μm or less, more preferably 30 nm or more and 1 μm or less.

  The metal layer 10 is a metal in which an electric field such that the electric field provided by the excitation light and the polarization induced by the electric field oscillate in opposite phase oscillates, that is, when a specific electric field is given, It is composed of a metal having a negative part of the real part (having a negative dielectric constant) and a dielectric constant of which the imaginary part dielectric constant is smaller than the absolute value of the dielectric constant of the real part. Gold, silver, aluminum, copper, platinum, their alloys etc. can be mentioned as an example of the metal which may have such a dielectric constant. When light in the visible light range is used as excitation light, the metal layer 10 preferably includes a layer made of gold, silver or copper among these metals. Moreover, the surface (end face in the thickness direction) of the metal layer 10 may or may not be a specific crystal plane. The metal layer 10 may be formed of a plurality of metal layers.

The metal layer 10 has a function of generating propagating surface plasmons in the electric field enhancing element 100 of the present embodiment. When light is incident on the metal layer 10 under the conditions to be described later, propagation type surface plasmons are generated in the vicinity of the surface (upper end surface in the thickness direction) of the metal layer 10. Moreover, in the present specification, the surface plasmons and polaritons (SPP: Surface Plasmon Plariton) are generated as a combination of vibration of charges near the surface of the metal layer 10 and vibration of coupling of electromagnetic waves.
It is called. The propagating surface plasmons generated in the metal layer 10 can interact (hybridize) with localized surface plasmons generated in the metal fine structure 40 described below under certain conditions. Furthermore, the metal layer 10 has a function of a mirror that reflects light (for example, refracted light of excitation light) toward the light transmitting layer 20 side.

1.2. Light Transmission Layer The electric field enhancing element 100 of the present embodiment has a light transmission layer 20 for separating the metal layer 10 and the metal fine structure 40. A translucent layer 20 is drawn in FIGS. The light transmissive layer 20 can have the shape of a film, a layer or a film. The light transmitting layer 20 is provided on the metal layer 10. Thereby, the metal layer 10 and the metal microstructure 40 can be separated spatially and electrically. In addition, the light transmitting layer 20 can transmit excitation light.

  The light transmitting layer 20 can be formed by, for example, methods such as vapor deposition, sputtering, CVD, and various coatings. When viewed in a plan view, the light transmitting layer 20 may be provided on the entire surface of the metal layer 10 or may be provided on a part of the surface of the metal layer 10.

The light transmitting layer 20 may have a positive dielectric constant, for example, silicon oxide (SiO _x such as SiO ₂ ), aluminum oxide (Al _x O _y such as Al ₂ O ₃ ), tantalum oxide (Ta ₂ O ₅ ) , Polymers such as silicon nitride (Si ₃ N ₄ ), titanium oxide (TiO _x such as TiO ₂ ), PMMA (Polymethyl methacrylate), ITO (Indium)
It can be formed by, for example, Tin Oxide. Also, the light transmitting layer 20 can be made of a dielectric. Furthermore, the light transmitting layer 20 may be composed of a plurality of layers of different materials.

  By setting the material of the light transmitting layer 20 to silicon oxide (refractive index: about 1.46) or aluminum oxide (refractive index: about 1.6 to 1.7), a higher degree of electric field enhancement can be obtained. There is a case.

When the light transmitting layer 20 is formed of a single layer, the effective refractive index n _eff of the light transmitting layer 20 is equal to the value of the refractive index of the material of the single layer. On the other hand, when the light transmitting layer 20 is composed of a plurality of layers, the effective refractive index n _eff of the light transmitting layer 20 transmits light of the product of the thickness of each layer constituting the light transmitting layer 20 and the refractive index of each layer. It is equal to the average thickness of the layer 20 divided by the total thickness G. The effective refractive index n _eff of the light transmitting layer 20 is not particularly limited, but is, for example, 1.3 or more and 2.0 or less, preferably 1.35 or more and 1.8 or less, and more preferably 1.4 or more and 1.7 or less It can be done. If the effective refractive index n _{eff of the} light transmitting layer 20 is in this range, it may be possible to obtain a higher degree of electric field enhancement.

1.3. Metal Microstructure Layer As shown in FIGS. 1 to 5, the metal microstructure layer 30 has metal microstructure columns 41 in which a plurality of metal microstructures 40 are arranged at a pitch P1 in the first direction, and A plurality of structural rows 41 are arranged at a pitch P2 larger than the pitch P1 in a second direction intersecting the first direction. As shown in FIGS. 3 and 4, the metal microstructure layer 30 is a layer including the metal microstructure 40, but other substances such as dielectrics and metals are disposed in portions other than the metal microstructure 40. Preferably, a gas (space) is disposed. In the present specification, the metal microstructure layer 30 refers to a region between the upper surface of the light transmitting layer 20 and the surface in contact with the tip of the metal microstructure 40 on the side away from the light transmitting layer 20. For example, the upper surface of the metal microstructure layer 30 is a virtual surface when the metal microstructure layer 30 contains the metal microstructure 40 and a gas, and the metal microstructure layer 30 has a metal microstructure. It shall also include the gas located laterally of 40.

(Metal fine structure)
The metal microstructures 40 are provided apart from the metal layer 10 in the thickness direction due to the presence of the light transmitting layer 20. The metal microstructure 40 is disposed on the metal layer 10 with the light transmitting layer 20 interposed therebetween. In the examples of FIGS. 1 to 5 of the present embodiment, the light transmitting layer 20 is provided on the metal layer 10, and the metal fine structure 40 is formed on the light transmitting layer 20. Are spaced apart in the thickness direction, and the metal microstructure layer 30 is formed.

  The shape of the metal microstructure 40 is not particularly limited. For example, when projected in the thickness direction of the metal layer 10 or the light transmitting layer 20, the shape of the metal microstructure 40 is circular, elliptical, polygonal, irregular or those (in plan view from the thickness direction) The shape may be a combination, and when projected in a direction orthogonal to the thickness direction, it may be a circle, an ellipse, a polygon, an irregular shape, or a shape combining them. In the examples of FIGS. 1 to 5, the metal microstructures 40 are all drawn in an elliptical columnar shape having a central axis in the thickness direction of the light transmission layer 20, but the shape of the metal microstructures 40 is limited thereto. I will not.

  FIG. 6 is a schematic view for explaining the shape and dimensions of the metal microstructure 40. As shown in FIG. In this specification, as shown in FIGS. 6A to 6C, the dimensions of the metal microstructure 40 in the first direction (X direction) and the second direction (Y direction) are defined as d1 and d2, respectively. . The dimension of the metal microstructure 40 in the third direction (Z direction) is defined as d3.

  The dimension d3 in the third direction (height direction) of the metal microstructure 40 refers to the length of a section in which the metal microstructure 40 can be cut by a plane perpendicular to the height direction, and is 1 nm or more and 300 nm or less. Further, the dimension d2 in the first direction orthogonal to the height direction of the metal microstructure 40 refers to the length of a section in which the metal microstructure 40 can be cut by a plane perpendicular to the first direction, and is 5 nm or more and 300 nm or less is there. The dimension d2 in the second direction orthogonal to the height direction of the metal microstructure 40 refers to the length of a section in which the metal microstructure 40 can be cut by a plane perpendicular to the second direction, and is 5 nm or more and 300 nm or less is there. As shown in FIG. 6D, for example, when the shape of the metal fine structure 40 is an elliptic cylinder whose central axis is in the height direction, the length of the oval when the elliptic cylinder is viewed in plan Even if the axis is inclined with respect to the first direction, the dimensions d1, d2 and d3 are defined as described above.

  For example, when the shape of the metal fine structure 40 is an elliptic cylinder whose central axis is in the height direction, the size in the height direction of the metal fine structure 40 (the height of the elliptic cylinder) is 10 nm to 300 nm, Preferably they are 20 nm or more and 100 nm or less, more preferably 30 nm or more and 50 nm or less. When the major axis of the ellipse in plan view of the elliptic cylinder is parallel to the first direction, the dimension d1 of the metal microstructure 40 in the first direction is equal to the length of the major axis of the ellipse, For example, it is 10 nm or more and 300 nm or less, preferably 20 nm or more and 200 nm or less, and more preferably 30 nm or more and 150 nm or less. Furthermore, when the major axis of the ellipse in plan view of the elliptic cylinder is parallel to the first direction (ie, the minor axis of the ellipse in plan view of the elliptic cylinder is parallel to the second direction) In the case where the dimension d2 of the metal microstructure 40 in the second direction is equal to the length of the minor axis of the ellipse, for example, 1 nm to 300 nm, preferably 20 nm to 200 nm, more preferably 30 nm to 150 nm is there.

  Then, in the electric field enhancing element 100 of the present embodiment, d1 and d2 are selected so as to satisfy the relationship of d1> d2 (that is, d1 / d2> 1). That is, in the electric field enhancing element 100 of the present embodiment, the metal microstructures 40 have an anisotropic shape having a longitudinal direction in the direction in which the metal microstructure rows 41 extend (the direction in which the pitch is narrow). In addition, when the value of d1 / d2 is 1.5 or more and 5.5 or less, a higher degree of electric field enhancement can be obtained, and more preferably, d1 / d2 is 2.5 or more and 5 or less.

Further, in the electric field enhancing element 100 of the present embodiment, if the relationship of 1.1 <(d1 / d3) is satisfied, the strength of the enhancing electric field can be further enhanced. Further, by satisfying the relationship d1>d3> d2, the strength of the enhanced electric field can be further enhanced. When satisfying these relationships, excitation light including light of wavelength 600 nm to 700 nm, preferably excitation light including light of 610 nm to 680 nm, more preferably excitation light including light of wavelength 620 nm to 500 nm, It is more preferable to use excitation light including light having a wavelength of 633 nm, particularly preferably using light having a wavelength of 632.8 nm, since the intensity of the enhanced electric field can be further increased.

  The material of the metal fine structure 40 is arbitrary as long as localized plasmons can be generated by irradiation of excitation light. Examples of the material that can generate localized plasmons by light near visible light include gold, silver, aluminum, copper, platinum, alloys thereof, and the like. Among these, as a material of the metal microstructure 40, Au or Ag is more preferable. In this way, stronger LSP resonance can be obtained, and the degree of enhancement of the entire device can be enhanced.

  The metal microstructure 40 can be formed by, for example, a method of forming a thin film by sputtering, vapor deposition or the like and then performing patterning, a micro contact printing method, a nanoimprinting method or the like. Also, the metal microstructure 40 can be formed by a colloid chemical method, and may be disposed at a position separated from the metal layer 10 by an appropriate method.

  The metal microstructure 40 has a function of generating localized plasmons in the electric field enhancing element 100 of the present embodiment. By irradiating the metal fine structure 40 with excitation light under the conditions to be described later, localized plasmons can be generated around the metal fine structure 40. The localized plasmons generated in the metal fine structure 40 can interact (hybridize) with the propagating plasmons generated in the metal layer 10 described above under certain conditions.

(Arrangement of metal microstructures)
As shown in FIGS. 1 to 5, a plurality of metal microstructures 40 are arranged side by side to constitute a metal microstructure row 41. The metal microstructures 40 are arranged side by side in the first direction orthogonal to the thickness direction (third direction) of the metal layer 10 in the metal microstructure row 41. In other words, the metal microstructure row 41 has a structure in which a plurality of metal microstructures 40 are arranged in the first direction orthogonal to the height direction. The first direction in which the metal microstructures 40 are arranged may not coincide with the longitudinal direction when the metal microstructures 40 have a longitudinal shape (in the case of an anisotropic shape). The number of metal microstructures 40 arranged in one metal microstructure column 41 may be plural, preferably 10 or more.

  Here, the distance between the centers of gravity of the metal microstructures 40 in the first direction in the metal microstructure column 41 is defined as a pitch P1 (see FIGS. 2 to 5). The interparticle distance of the two metal microstructures 40 in the metal microstructure row 41 extending in the first direction is equal to the pitch P1 minus the dimension d1 of the metal microstructure 40. When the interparticle distance is small, the intensity of localized plasmons acting between particles tends to increase. The distance between particles is 1 nm or more and 530 nm or less, preferably 5 nm or more and 200 nm or less, and more preferably 5 nm or more and 150 nm or less.

  The pitch P1 of the metal microstructures 40 in the first direction in the metal microstructure column 41 is 6 nm or more and 535 nm or less, preferably 10 nm or more and 400 nm or less, and more preferably 20 nm or more and 350 nm or less.

Pitch P1 of the first direction of the metal microstructure 40 in the metal microstructure column 41 and is 20nm or 350nm or less, by using the pumping light of the wavelength lambda _i of less than 400 nm 700 nm (excitation light), 1100 cm ^-1 Both excitation light and Raman scattered light can be sufficiently enhanced when measuring a sample that exhibits less than a Raman shift.

  The metal microstructure row 41 is constituted by a plurality of metal microstructures 40 arranged at a pitch P1 in the first direction, but the distribution, strength, etc. of localized plasmons generated in the metal microstructure 40 are the metal microstructure It also depends on 40 sequences. Therefore, the localized plasmons interacting with the propagating plasmons generated in the metal layer 10 are not only localized plasmons generated in the single metallic microstructure 40 but also the metallic microstructures 40 in the metallic microstructure row 41. It is a localized plasmon in consideration of the arrangement.

  As shown in FIGS. 1 to 5, the metal microstructure rows 41 are arranged side by side at a pitch P2 in the thickness direction of the metal layer 10 and in a second direction intersecting the first direction. The number of the metal microstructure rows 41 may be plural, as long as it is plural, preferably ten or more.

  Here, the distance between the centers of gravity in the second direction of the adjacent metal microstructure rows 41 is defined as a pitch P2. When the metal microstructure row 41 includes a plurality of rows, the pitch P2 indicates the position of the center of gravity in the second direction of the plurality of rows and the second direction of the plurality of rows of the metal microstructure row 41 adjacent to each other. Point to the distance between the position of the center of gravity at.

  The pitch P 2 between the metal microstructure rows 41 is larger than the pitch P 1 between the metal microstructures 40. That is, there is a relationship of P1 <P2 between the pitch P1 and the pitch P2. By having such a relationship, the arrangement of the metal microstructures 40 in the electric field enhancing element 100 has anisotropy when viewed from the thickness direction of the light transmitting layer 20.

  The pitch P2 between the metal fine structure rows 41 can be set according to the conditions described in “1.4. Propagation-type plasmons and localized-type plasmons” below, for example, 10 nm or more and 10 μm or less, preferably 20 nm or more and 2 μm The thickness is more preferably 30 nm or more and 1500 nm or less, still more preferably 60 nm or more and 1310 nm or less, and particularly preferably 60 nm or more and 660 nm or less.

When measuring a sample showing a Raman shift of less than 1100 cm ⁻¹ using excitation light with a wavelength λ _i of 400 nm or more and less than 700 nm as the pitch P2 between the metal microstructure rows 41 is 60 nm or more and 660 nm or less Both excitation light and Raman scattered light can be sufficiently enhanced.

  Note that a line in the first direction in which the metal microstructure row 41 extends, and a line connecting the two metal microstructures 40 which are two metal microstructures 40 respectively belonging to the adjacent metal microstructure row 41 and which are closest to each other The angle formed by is not particularly limited, and may or may not be a right angle. For example, as shown in FIG. 2, the angle formed by the two may be a right angle, and as shown in FIG. 5, the angle formed by both may not be a right angle. That is, even if the irreducible basic unit lattice has a rectangular shape when the arrangement of the metal microstructures 40 viewed from the thickness direction is regarded as a two-dimensional lattice in which the positions of the metal microstructures 40 are lattice points It may be in the shape of a parallelogram. In addition, a line in the first direction in which the metal microstructure row 41 extends, and a line connecting two metal microstructures 40 which are two metal microstructures 40 respectively belonging to the adjacent metal microstructure row 41 and which are closest to each other In the case where the angle formed by is not perpendicular, two metal microstructures 40 respectively belonging to the adjacent metal microstructure structure row 41 and the distance between the two metal microstructures 40 closest to each other is also taken as a pitch P 2 Good.

1.4. Propagation Type Plasmon and Localized Plasmon First, the propagation type plasmon will be described. FIG. 7 is a graph of dispersion relation showing dispersion curves of excitation light and gold. Normally, even if light is incident on the metal layer 10 at an incident angle (irradiation angle θ) of 0 to 90 degrees, no propagation type plasmon is generated. For example, when the metal layer 10 is made of Au,
This is because, as shown in FIG. 7, the dispersion curve of the light line (LightLine) and the SPP of Au does not have an intersection point. In addition, even if the refractive index of the medium through which light passes changes, the SPP of Au also changes according to the refractive index of the periphery, so there is also no intersection point. In order to give rise to a propagation type plasmon with an intersection point, a metal layer is provided on the prism as in the Kretschmann arrangement, and the wave number of excitation light is increased by the refractive index of the prism, or the wave number of the light line is determined by the diffraction grating. There is a way to increase it. FIG. 7 is a graph showing a so-called dispersion relation (the vertical axis represents angular frequency [ω (eV)] and the horizontal axis represents wave number vector [k (eV / c)].

  Further, the angular frequency ω (eV) on the vertical axis of the graph of FIG. 7 has a relationship of wavelength λ (nm) = 1240 / ω (eV), and can be converted to wavelength. Also, the wave number vector k (eV / c) on the horizontal axis of the graph has a relationship of k (eV / c) = 2π · 2 / [wavelength λ (nm) / 100]. Therefore, for example, when the wavelength λ = 600 nm, k = 2.09 (eV / c). The irradiation angle is an irradiation angle of the excitation light, and is an inclination angle from the thickness direction of the metal layer 10 or the light transmitting layer 20 or the height direction of the metal fine structure 40.

The dispersion curve of SPP of Au is shown in FIG. 7. Generally, the angular frequency of the excitation light incident on the metal layer 10 is ω _i , the speed of light in vacuum is c, and the metal constituting the metal layer 10 is Assuming that the dielectric constant is ε ₁ (ω) and the peripheral dielectric constant is ε ₂ , the dispersion curve of SPP of the metal is
K _SPP = ω _i / c [ε ₂ · ε ₁ (ω _i ) / (ε ₂ + ε ₁ (ω _i ))] ^1/2 (3)
Given by Note that “·” or “x” in the formulas of the present specification means a product operator.

On the other hand, a virtual diffraction grating having an interval Q, where θ represents the irradiation angle of excitation light and the inclination angle from the thickness direction of the metal layer 10 or the light transmission layer 20 or the height direction of the metal fine structure 40 is θ. The wavenumber K of the passed light is given by equation (4)
K = n ₂ · (ω _i / c) · sin θ + m · 2π / Q (m = ± 1, ± 2,,) (4)
The relationship appears as a straight line, not a curve, on the graph of the dispersion relation.

Here, n ₂ is the peripheral refractive index, and assuming that the extinction coefficient is 、, the real part ε ₂ ′ and the imaginary part ε ₂ ′ ′ of the relative permittivity ε _{2 at} the light frequency are respectively ε ₂ ′ = n _{² 2} -κ _{2 2,} given by _{ε 2 "= 2n 2 κ 2} , if the surrounding material transparent, since it is κ ₂ ~0, ε ₂ are real, ε ^₂ = _{n 2 2} next , N ₂ = ε ₂ ^1/2 . m represents the order of diffracted light.

In the dispersion relationship graph, when the dispersion curve of the metal SPP (the above equation (3)) and the straight line of the diffracted light (the above equation (4)) have an intersection, the propagation plasmon is excited. That is, when the relationship of K _SPP = K is established, propagation type plasmons are excited in the metal layer 10.

Therefore, the following formula (5) is obtained from the above formulas (3) and (4),
(Ω _i / c) · {ε ₂ · ε ₁ (ω _i ) / (ε ₂ + ε ₁ (ω _i ))} ^1/2 = ε ₂ ^1/2 · (ω _i / c) · sin θ + 2 mπ / Q ( m = ± 1, ± 2,,) (5)
It is understood that propagating plasmons are excited in the metal layer 10 if the relationship of the equation (5) is satisfied. In this case, in the example of SPP of Au shown in FIG. 7, the inclination and / or intercept of the light line can be changed by changing θ and m, and the light line relative to the dispersion curve of SPP of Au The straight lines of can be crossed.

The angular frequency of the localized plasmon excited in the row of the metal microstructure 40 is ω, the dielectric constant of the metal constituting the metal layer 10 is ε (ω), and the dielectric constant of the periphery of the metal microstructure 40 is ε If the speed of light in vacuum is c, the irradiation angle of the excitation light is θ, and the inclination angle from the thickness direction of the metal layer 10 is θ, then (ω / c) · {ε · ε (ω) / (ε + ε) (Ω)) ^1/2 = ε ^1/2 · (ω / c) · sin θ + 2aπ / Q (a = ± 1, ± 2,,) (2)
Relationship.

  Next, localized plasmons will be described.

The conditions for generating localized plasmons in the metal microstructure 40 are determined by the real part of the dielectric constant:
Real [ε ₁ (ω)] = − 2ε ₂ (6)
Given by Assuming that the refractive index n ₂ at the periphery is 1, ε ₂ = n ₂ ² −κ ₂ ² = 1 and thus Real [ε ₁ (ω)] = − 2.

FIG. 8 is a graph showing the relationship between the dielectric constant of Ag and the wavelength. For example, the dielectric constant of Ag is as shown in FIG. 8, and localized plasmons are excited at a wavelength of about 400 nm or more. When the layer 10 (Au film or the like) is separated by the light transmission layer 20 (SiO ₂ or the like), the excitation peak wavelength of the localized plasmon is red-shifted (longer wavelength side) due to the influence of the gap. shift. The amount of shift depends on the dimensions of Ag diameter, Ag thickness, Ag particle spacing, dielectric layer thickness, etc., but exhibits wavelength characteristics where localized plasmon peaks at, for example, 500 nm to 900 nm.

  In addition, localized plasmons, unlike propagating plasmons, are plasmons that have no velocity and do not move, and when plotted on a dispersion relationship graph, the slope is zero, that is, ω / k = 0.

  FIG. 9 is a graph showing an example of a dispersion curve of a metal, localized plasmons, and a dispersion relationship of excitation light. The electric field enhancing element 100 of the present embodiment obtains an extremely large degree of enhancement of the electric field by electromagnetically coupling (propagating plasmons and localized plasmons). That is, in the graph of the dispersion relation, the electric field enhancing element 100 of the present embodiment does not set the intersection of the straight line of the diffracted light and the dispersion curve of the metal SPP as an arbitrary point, One of the features is to make both intersect in the vicinity of the point giving the maximum or maximum enhancement in localized plasmons generated in the structural array 41) (see FIG. 9).

  In other words, in the field enhancement device 100 of the present embodiment, in the dispersion relationship graph, enhancement of maximum or maximum in the dispersion curve of SPP of metal and localized plasmons generated in the metal fine structure 40 (metal fine structure row 41) It is designed so that the straight line of diffracted light passes near the point of intersection with the angular frequency of excitation light (the line parallel to the horizontal axis attached to LSP in the dispersion relation graph of FIG. 9) giving .

  Here, the vicinity of the intersection point, when converted to the wavelength, is within a wavelength range of about ± 10% of the wavelength of the excitation light, or ± P1 of the wavelength of the excitation light (metal fine structure 40 Of the length of the pitch P1) in the metal micro-structure row 41 of FIG.

In the above equations (3), (4) and (5), the angular frequency of the excitation light incident on the metal layer 10 is ω _i to indicate the conditions under which the propagation type plasmon is excited. In the electric field enhancing element 100 of the present embodiment, ω _i in the above formulas (3), (4) and (5) is given by: This is the angular frequency of the excitation light that gives the maximum or maximum enhancement in localized plasmons generated in the metal fine structure 40 (the metal fine structure array 41) or the angular frequency in the vicinity thereof.

  Therefore, when the angular frequency of the localized plasmon excited in the metal fine structure row 41 is ω, if the above equation (5) is satisfied, a hybrid of the localized plasmon and the propagating plasmon is generated. Can.

Therefore, the angular frequency of the localized plasmon generated in the metal micro-structure row 41 in which the metal micro-structures 40 are arranged at the pitch P1 is ω, and in the graph of the dispersion relationship, the vicinity of the position of ω of the dispersion curve of metal SPP If a straight line of diffracted light (order m _diff ) diffracted by being incident on a virtual diffraction grating with an interval Q at an irradiation angle θ passes (if equation (5) is satisfied), localization It is possible to generate a hybrid of the type plasmon and the propagation type plasmon and to obtain an extremely large degree of enhancement. In other words, in the graph of the dispersion relation shown in FIG. 8, by changing the inclination and / or intercept of the light line and changing the light line to pass near the intersection of SPP and LSP, localized type Hybrids of plasmons and propagating plasmons can be generated, and an extremely large degree of enhancement can be obtained.

  The pitch P2 between the metal microstructure rows 41 is set as follows. When the first-order diffracted light (m = 1) is used at normal incidence (incident angle θ = 0), equation (5) can be satisfied by setting the pitch P2 to the interval Q. However, depending on the selected incident angle θ and the order m of the diffracted light, the interval Q which can satisfy the equation (5) will have a width. In this case, the incident angle θ is preferably a tilt angle from the thickness direction to the second direction, but may be a tilt angle in the direction including the component in the first direction.

Therefore, the range of the pitch P2 that can generate a hybrid of the localized plasmon and the propagating plasmon in consideration of the fact that it is near the intersection point (width of ± P1) is the formula (1),
Q−P1 ≦ P2 ≦ Q + P1 (7)
It becomes.

  On the other hand, although the pitch P2 is the pitch in the second direction between the metal microstructure rows 41, the pitch between the two metal microstructures 40 belonging to the adjacent metal microstructure rows 41 is that of the two metal microstructures 40. Depending on the choice, the line connecting them can be tilted with respect to the second direction. That is, two metal microstructures 40 belonging to the adjacent metal microstructure array 41 can be selected so as to have a distance longer than the pitch P2. In FIG. 2, an auxiliary line for describing this is drawn, and along a direction inclined to the second direction, two metal microstructures 40 separated by a distance longer than the pitch P2 are adjacent to each other. It can be selected from the metal microstructure column 41. As described above, since the adjacent metal microstructure rows 41 are the same metal microstructure rows 41, the arrangement of the metal microstructures 40 viewed from the thickness direction is the position of the metal microstructure 40 as a grid point. It can be regarded as a two-dimensional grid. Then, in this two-dimensional grating, there is an interval (diffraction grating) longer than the pitch P2.

  Therefore, in the matrix of the metal microstructures 40 arranged at the pitch P1 and the pitch P2, diffracted light can be expected from the diffraction grating having a distance larger than the pitch P2. Therefore, the inequality on the left side of the equation (7) can be P1 <P2. In other words, even in the case where the pitch P2 is smaller than Q-P1 in the equation (7), there may exist a diffraction grating having the interval Q which can satisfy the equation (5). Hybrids with plasmons can be generated. Therefore, the pitch P2 may be smaller than Q-P1, and the relationship P1 <P2 may be satisfied.

From the above, the pitch P2 between the metal fine structure rows 41 in the electric field enhancing element 100 of the present embodiment is given by the following formula (1)
P1 <P2 ≦ Q + P1 (1)
By satisfying the following relationship, it is possible to generate a good hybrid of localized plasmon and propagating plasmon.

1.5. Excitation light The wavelength λ _{i of the} excitation light incident on the electric field enhancing element 100 is limited as long as it generates localized plasmons and can satisfy the relationship of the above equation (5) or equation (2). Alternatively, it can be an electromagnetic wave including ultraviolet light, visible light, and infrared light. In this embodiment, the excitation light is a linearly polarized light in the same direction as the first direction, the light of the wavelength lambda _i. In the present embodiment, the excitation light is linearly polarized light in the same direction as the first direction of the electric field enhancing element 100 (the extending direction of the metal microstructure row 41) of the electric field. In this way, the electric field enhancing element 100 can obtain a very large degree of light enhancement.

The wavelength λ _{i of the} excitation light can be, for example, 400 nm or more and 800 nm or less, preferably 500 nm or more and 800 nm or less, more preferably 630 nm or more and 700 nm or less. In this way, when measuring a sample with a Raman shift of 1100 cm ⁻¹ , it is possible to further enhance the degree of enhancement of both the excitation light and the Raman scattered light.

1.6. Enhancement The relationship between the electric field Ex in the X direction (first direction) and the magnitude of the electric field Ez in the Z direction (thickness direction), that is, the vector changes according to the mesh position of FDTD calculation. When linearly polarized light in the X direction is used as excitation light, the electric field Ey in the Y direction (second direction) can be almost ignored. Therefore, the degree of enhancement can be grasped using the square root of the sum of squares of Ex and Ez, that is, SQRT (Ex ² + Ez ² ). In this way, they can be compared to one another as scalars of the local electric field.

  In the experimental examples and figures in the present specification, the first direction may be referred to as the X direction, and that direction may be expressed by the notation “X”. Also, the second direction may be referred to as the Y direction, and that direction may be expressed by the notation “Y”. Also, the thickness direction of the element may be referred to as the Z direction, and that direction may be expressed by the notation “Z”.

SERS (Surface Enhancement Raman Scattering) effect uses Hot Spot Density (HSD) as SERS EF (Enhancement Factor), where the electric field enhancement degree at the wavelength of excitation light is Ei, the electric field enhancement degree at the wavelength after Raman scattering is Es The following formula (a)
SERS EF = Ei ² × Es ² × HSD (a)
Is represented by

When considering the degree of enhancement of the electric field enhancing element 100, it is necessary to consider so-called hot spot density (HSD). That is, the degree of light enhancement by the electric field enhancing element 100 depends on the number of metal microstructure layers 30 per unit area of the electric field enhancing element 100. In the electric field enhancing element 100 of the present embodiment, the pitch P1 and the pitch P2 are arranged such that the relationship of the above-mentioned equation (1) and equation (2) is satisfied. Therefore, in consideration of HSD, the degree of SERS enhancement of the electric field enhancing element 100 is proportional to (Ei ² + Es ² ) / (P1 · P2). In the experimental examples described below, for comparison in the same HSD, the above equation relates to (a), for simplicity, is defined as ^{SERS EF = Ei 2 × Es 2} .

1.7. Others In the above description, the metal fine structure is an elliptic cylinder, but the shape is not limited, and even if it is a prism, a spheroid, or a random shape, d1, d2, and d3 can be similarly defined. Also, the sizes of the plurality of metal microstructures do not have to be exactly the same. Further, the dimension (d1) in the first direction of the metal microstructure may be smaller than the wavelength of the incident light (excitation light). Furthermore, the materials of the metal fine structure and the metal layer may be the same as or different from each other as long as they have surface plasmon resonance. Furthermore, the manufacturing method of each element (a metal layer, a light transmission layer, a metal fine structure) of a substrate is not limited.

2. Analyzer The analyzer of the present embodiment includes the above-described electric field enhancing element, a light source, and a detector. Hereinafter, the case where the analyzer is a Raman spectrometer will be described as an example.

  FIG. 10 is a view schematically showing a Raman spectroscopy apparatus 200 according to the present embodiment. The Raman spectroscopy apparatus 200 detects and analyzes Raman scattered light from a target substance (qualitative analysis, quantitative analysis), and as shown in FIG. 10, a light source 210, a gas sample holding unit 110, and detection It includes a unit 120, a control unit 130, and a case 140 in which the detection unit 120 and the control unit 130 are accommodated. The gas sample holder 110 includes the electric field enhancing element according to the present invention. Hereinafter, an example including the above-described electric field enhancing element 100 will be described.

  The gas sample holding unit 110 includes an electric field enhancing element 100, a cover 112 covering the electric field enhancing element 100, a suction flow channel 114, and a discharge flow channel 116. The detection unit 120 includes a light source 210, lenses 122a, 122b, 122c, and 122d, a half mirror 124, and a light detector 220. The control unit 130 includes a detection control unit 132 that processes the signal detected by the light detector 220 to control the light detector 220, and a power control unit 134 that controls power and voltage of the light source 210 and the like. doing. As shown in FIG. 10, the control unit 130 may be electrically connected to a connection unit 136 for connection to the outside.

  In the Raman spectroscopy apparatus 200, when the suction mechanism 117 provided in the discharge flow channel 116 is operated, the pressure in the suction flow channel 114 and the discharge flow channel 116 becomes negative pressure, and the target substance to be detected is detected from the suction port 113. The contained gas sample is aspirated. The dust removal filter 115 is provided in the suction port 113, and can remove comparatively large dust, a part of water vapor, and the like. The gas sample passes through the suction channel 114 and the discharge channel 116 and is discharged from the discharge port 118. The gas sample contacts the metal microstructures 40 of the electric field enhancing element 100 as it passes through such a path.

  The shapes of the suction flow channel 114 and the discharge flow channel 116 are such that light from the outside does not enter the electric field enhancing element 100. As a result, since light which is noise other than the Raman scattered light does not enter, it is possible to improve the S / N ratio of the signal. The material constituting the flow channels 114 and 116 is, for example, a material or a color that hardly reflects light.

  The shapes of the suction channel 114 and the discharge channel 116 are such that the fluid resistance to the gas sample is reduced. This enables highly sensitive detection. For example, by making the shapes of the channels 114 and 116 as smooth as possible by eliminating the corners, it is possible to eliminate the retention of the gas sample at the corners. As the suction mechanism 117, for example, a fan motor or a pump having a static pressure and an air volume according to the flow path resistance is used.

In the Raman spectrometer 200, the light source 210 irradiates the electric field enhancing element 100 with excitation light. The light source 210 is light (linearly polarized light in the same direction as the first direction) linearly polarized in the first direction of the electric field enhancing element 100 (the direction in which the metal microstructures 40 are aligned and the metal particle row 31 extends). It is arranged to be able to irradiate. Although not shown, the incident angle θ of the excitation light emitted from the light source 210 may be appropriately changed according to the excitation condition of the surface plasmon of the electric field enhancing element 100. The light source 210 may be installed in a goniometer or the like (not shown).

  The light emitted by the light source 210 is the same as described in the section “1.5. Excitation light”. Specifically, as the light source 210, a semiconductor laser, a gas laser, a halogen lamp, a high pressure mercury lamp, a xenon lamp, etc. can be appropriately provided with a wavelength selection element, a filter, a polarizer and the like.

  The light emitted from the light source 210 is condensed by the lens 122a, and then enters the electric field enhancing element 100 through the half mirror 124 and the lens 122b. From the electric field enhancing element 100, SERS light is emitted, and the light reaches the light detector 220 through the lens 122b, the half mirror 124, and the lenses 122c and 122d. That is, the light detector 220 detects the light emitted from the electric field enhancing element 100. Since the SERS light includes Rayleigh scattered light of the same wavelength as the incident wavelength from the light source 210, the Rayleigh scattered light may be removed by the filter 126 of the light detector 220. The light from which the Rayleigh scattered light is removed is received as a Raman scattered light by the light receiving element 128 via the spectroscope 127 of the light detector 220. As the light receiving element 128, for example, a photodiode is used.

  The spectroscope 127 of the light detector 220 is formed of, for example, an etalon or the like using Fabry-Perot resonance, and can make the passing wavelength band variable. A Raman spectrum specific to the target substance is obtained by the light receiving element 128 of the light detector 220. For example, the signal strength of the target substance may be detected by comparing the obtained Raman spectrum with data held in advance. it can.

  The Raman spectroscopy apparatus 200 includes the electric field enhancing element 100, the light source 210, and the light detector 220, and if the target substance can be adsorbed to the electric field enhancing element 100 and the Raman scattered light can be acquired, It is not limited.

  Moreover, when detecting Rayleigh scattered light, the Raman spectroscopy apparatus 200 may not have the filter 126, and may split Rayleigh scattered light and Raman scattered light by a spectrometer.

  The Raman spectroscopy apparatus 200 includes the electric field enhancing element 100 described above. According to such a Raman spectroscopy apparatus 200 (analyzer), a very high degree of enhancement can be obtained in the enhancement degree (reflectance) spectrum, and the target substance can be detected and analyzed with high sensitivity.

3. Electronic Device Next, an electronic device 300 according to the present embodiment will be described with reference to the drawings. FIG. 11 is a view schematically showing an electronic device 300 according to the present embodiment. The electronic device 300 can include the analysis device (Raman spectroscopy device) according to the present invention. Hereinafter, an example including the above-described Raman spectrometer 200 as an analyzer according to the present invention will be described.

  As shown in FIG. 11, the electronic device 300 includes a Raman spectroscopy apparatus 200, a computing unit 310 that computes health care information based on detection information from the light detector 220, and a storage unit 320 that stores health care information. And a display unit 330 for displaying health and medical information.

  The calculation unit 310 is, for example, a personal computer or a personal digital assistant (PDA), and receives detection information (signals and the like) transmitted from the light detector 220. The calculation unit 310 calculates health care information based on the detection information from the light detector 220. The calculated health care information is stored in the storage unit 320.

  The storage unit 320 is, for example, a semiconductor memory, a hard disk drive, or the like, and may be configured integrally with the calculation unit 310. The health care information stored in the storage unit 320 is sent to the display unit 330.

  The display unit 330 is configured of, for example, a display plate (such as a liquid crystal monitor), a printer, a light emitter, a speaker, and the like. The display unit 330 displays or issues a notification so that the user can recognize the content based on the health care information or the like calculated by the calculation unit 310.

  Health-care information includes at least one biological substance selected from the group consisting of bacteria, viruses, proteins, nucleic acids, and antigens and antibodies, or at least one compound selected from inorganic molecules and organic molecules. It can contain information about the presence or absence or quantity.

  The electronic device 300 includes the above-described Raman spectrometer 200. Therefore, in the electronic device 300, detection of a trace substance can be efficiently performed with high sensitivity, and highly accurate health care information can be provided.

  For example, the electric field enhancing element according to the present invention can also be used as an affinity sensor or the like which detects the presence or absence of adsorption of a substance, such as the presence or absence of adsorption of an antigen in an antigen-antibody reaction. The affinity sensor injects white light into the sensor, measures the wavelength spectrum with a spectrometer, and detects the shift amount of the surface plasmon resonance wavelength due to adsorption, thereby making the adsorption of the detection substance on the sensor chip highly sensitive. It can be detected.

4. EXPERIMENTAL EXAMPLES Experimental examples will be shown below to further explain the present invention, but the present invention is not limited at all by the following examples.

  In Experimental Example 1-3, a near-field solution (distribution of enhanced electric field) was obtained by FDTD simulation. The calculation was performed using FDTD soft FullWAVE of Rsoft (currently Cybernet Systems Co., Ltd.). The excitation light was linearly polarized light in the X direction, and was vertically incident in parallel to the Z direction (the thickness direction of the substrate).

In addition, a gold (Au) layer thick enough to prevent light transmission is used as the metal layer, and a SiO ₂ layer with a refractive index of 1.46 is formed as the light transmitting layer on the metal layer (gold) (Experimental Example 1, 2) and GSPP (Gap type Surface Plasmon) in which gold of elliptical columnar shape is formed at a constant period as a metal fine structure on a light transmitting layer using an Al ₂ O ₃ layer (Experimental Example 3) having a refractive index of 1.64 It was a Polariton model. The material of the metal layer and the metal fine structure is not limited, and in the wavelength region of excitation light, it is possible to generate plasmons if the real part of the dielectric constant is large and negative and the imaginary part is smaller than the real part. it can. The dimensions of the metal microstructure were selected so as to increase the interaction between LSP and PSP.

  FIG. 12 shows a calculation model used in each experimental example. As schematically shown in FIGS. 12A and 12B, the metal microstructure has an X width of d1, a metal microstructure Y width of d2, and a height of the metal microstructure of d3.

The common parameter of Experimental example 1-3 is shown.
The metal layer was gold 150 nm thick.
The pitch P1 in the X direction (first direction) is 140 nm, and the pitch P2 in the Y direction (second direction) is 400 nm.
The material of the metal microstructure is gold.
・ The refractive index of gold used the Lorentz Dolde model.

The enhancement effect of SERS is known to be proportional to Ei ² × Es ^2, where E i is the electric field enhancement degree at the wavelength of excitation light and Es is the electric field enhancement degree at the wavelength after Raman scattering. In Experimental Examples 1 to 3, the excitation wavelength was set to 633 nm, and Ei ² × Es ² was designed to be the highest with respect to the scattering wavelength 677 nm. This design can amplify a Raman peak whose Raman shift is less than about 1100 cm ⁻¹ .

4.1. Experimental example 1 (change d1 / d2)
In the calculation model of FIG. 12, assuming that the refractive index of the dielectric of the light transmitting layer is 1.46 (assuming SiO ₂ ), d1 / d2 = 2, 3, 4 ... for d3 = 30 nm and 50 nm. And changed. At this time, while maintaining the ratio of d1 / d2, the dimensions of d1 and d2 were changed, and the film thickness of the light transmitting layer was changed, to obtain a condition under which Ei ² × Es ² is maximized. Further, as a comparison, a model (cylindrical model) with d1 / d2 = 1 was calculated.

FIGS. 13 and 14 show the results when d3 = 30 nm. Table 1 shows the numerical values of each parameter. FIG. 13 is a graph in which Ei ² × Es ² is plotted against d1 / d2 (fixed at d3 = 30 nm). FIG. 14 is a graph in which d1 / d3 is plotted against d1 / d2.

It can be seen from FIG. 13 that the value of Ei ² × Es ² increases as the value of d1 / d2 increases, and turns to decrease at a certain value. However, it has been found that a higher degree of electric field enhancement can be obtained up to about d1 / d2 = 6 as compared to d1 / d2 = 1 (cylindrical metal fine structure).

Further, it is understood from FIG. 14 that the value of d1 / d3 monotonously decreases as the value of d1 / d2 increases. The two values are linearly correlated, and the relationship is as shown by the broken line in FIG. This is because, as shown in Table 1, as a result of pursuing the condition that Ei ² × Es ² is maximized, the value of d 1 decreases as d 1 / d 2 increases. That is, as the shape of the metal fine structure extends (is elongated) in the first direction, the plasmon resonance wavelength shifts to a longer wavelength, so d1 is decreased to maintain the resonance wavelength.

15 and 16 show the results when d3 = 50 nm. Table 2 shows the numerical values of each parameter. FIG. 15 is a graph plotting Ei ² × Es ² against d1 / d2 (fixed at d3 = 50 nm). FIG. 16 is a graph in which d1 / d3 is plotted against d1 / d2.

Referring to FIG. 15, also in the case of d3 = 50 nm, the value of Ei ² × Es ² increases as the value of d1 / d2 increases as in the case of d3 = 30 nm, and decreases at a certain value. I understand that. However, it has been found that a higher degree of electric field enhancement can be obtained up to about d1 / d2 = 6 as compared to d1 / d2 = 1 (cylindrical metal fine structure).

Further, it can be seen from FIG. 16 that, also in the case of d3 = 50 nm, the value of d1 / d3 monotonously decreases as the value of d1 / d2 increases, as in the case of d3 = 30 nm. The two values are linearly correlated, and the relationship is as shown by the broken line in FIG. This is because, as shown in Table 2, as a result of pursuing the condition that Ei ² × Es ² is maximized, the value of d 1 becomes smaller as d 1 / d 2 becomes larger. That is, as the shape of the metal fine structure extends (is elongated) in the first direction, the plasmon resonance wavelength shifts to a longer wavelength, so d1 is decreased to maintain the resonance wavelength.

  As shown in FIGS. 13, 15, Table 1, Table 2, as the shape of the metal microstructure extends in the first direction (is elongated), higher degree of electric field enhancement can be obtained, while the shape extends in the first direction. It has been found that if it is too large (very slender), the degree of electric field enhancement decreases.

  From the results of this experimental example, it is found that a higher degree of electric field enhancement can be obtained in the region of d1 / d2> 1 (that is, d1 / d2) as the shape of the metal fine structure than the metal fine structure of the non-anisotropic shape There was found. Further, a higher degree of electric field enhancement can be obtained when d1 / d2 is 1.5 or more and 5.5 or less, and a further higher degree of electric field enhancement can be obtained when d1 / d2 is 2.5 or more and 5 or less I understood.

  In addition, it was also found that a high degree of electric field enhancement can be obtained at d1 / d3> 1.1 or more for the height (d3) of the metal microstructure. Furthermore, it can be seen from Tables 1 and 3 that a higher degree of electric field enhancement can be obtained when d1> d3> d2 than when d1> d2> d3.

4.2. Experimental example 2 (change d3)
In the calculation model of FIG. 12, assuming that the refractive index of the light transmitting layer is 1.46 (assuming SiO ₂ ) and d1 / d2 = 2, d3 = 20 nm, 30 nm, 40 nm, 50 nm, and 60 nm I made it. By changing the dimensions of d1, d2 and d3 and the film thickness of the light transmitting layer, conditions for maximizing Ei ² × Es ² were determined. The results are plotted in FIG. Table 3 shows the numerical values of each parameter. FIG. 17 is a graph in which Ei ² × Es ² is plotted with respect to d1 / d3 (fixed as d1 / d2 = 2).

From FIG. 17 and Table 3, it can be seen that, when d3 is increased, Ei ² × Es ² shows the maximum value at d3 = 50 nm. It was found that Ei ² × Es ² slightly decreased at d ³ = 60 nm.

4.3. Experimental Example 3 (Summary of Experimental Examples 1 and 2)
In FIG. 18, the data of the above-mentioned Experimental Example 1 and Experimental Example 2 are taken with d1 / d2 on the horizontal axis and d1 / d3 on the vertical axis, and the relative intensity of Ei ² × Es ² is shown by the size of a circle. It represents a shows a plot (a Ei ² × Es ² values are as shown in each Table.). The plots of d1 / d2 = 1.5 and d1 / d3 = 3 are plots of d3 = 50 nm obtained by complementing the plots of FIG. 15 and FIG.

Referring to FIG. 18, the intensity of Ei ² × Es ² is high in the entire region of d1 / d2> 1. That is, the degree of electric field enhancement at all other points was higher than the two points on the line of d1 / d2 = 1 in the graph of FIG. With regard to d1 / d3, the degree of electric field enhancement was high in the region of 1.1 or more, and the degree of electric field enhancement was high in the region of 2.5 or less or 1.7 or less.

FIG. 19 shows the data of the above experimental example 1 and experimental example 2 with d1 / d2 taken on the horizontal axis and d1 / d3 taken on the vertical axis, and the relative intensities of Ei ² × Es ² plotted in the color shade (Ei ² × Es ² values are as indicated in each table).

  As shown in the auxiliary line in FIG. 19, it was found that the region where higher electric field enhancement can be obtained is d1 / d2> 1, d1 / d3> 1.1, and d1> d3> d2. .

4.4. Experimental Example 3 (Change the refractive index of the light transmitting layer)
In the calculation model of FIG. 12, assuming that the refractive index of the light transmitting layer is 1.64 (assuming Al ₂ O ₃ ), d 1 / d 2 = 2, 3, 4 ··· for d 3 = 30 nm I made it. Here, while maintaining the value of d1 / d2, by changing the thickness of the dimensions and the light-transmitting layer of d1 and d2, to determine the conditions Ei ² × Es ² is maximized. Further, as a comparison, a model (cylindrical model) with d1 / d2 = 1 was calculated.

FIG. 20 and FIG. 21 show the results when d3 = 30 nm. Table 4 shows the numerical values of each parameter. FIG. 20 is a graph in which Ei ² × Es ² is plotted against d1 / d2 (fixed at d3 = 30 nm). FIG. 21 is a graph in which d1 / d3 is plotted against d1 / d2.

Referring to FIG. 20, FIG. 21 and Table 4, even when the refractive index of the light transmitting layer is changed, the value of Ei ² × Es ² is obtained as the value of d1 / d2 increases as in the experimental examples 1 and ² . The value increases, and it turns out that it turns to decrease at a certain value. However, it has been found that a higher degree of electric field enhancement can be obtained up to about d1 / d2 = 5 as compared to d1 / d2 = 1 (cylindrical metal fine structure).

Also, it can be seen from FIG. 21 that as the value of d1 / d2 increases, the value of d1 / d3 monotonously decreases. The two values are linearly correlated, and the relational expression is as shown by a broken line in FIG. This is because, as shown in Table 4, as a result of pursuing the condition that Ei ² × Es ² is maximized, the value of d 1 decreases as d 1 / d 2 increases.

  As a result of increasing the refractive index of the light transmitting layer from 1.46 (Experimental Examples 1 and 2) to 1.64, the value of d1 is smaller than that of Experimental Examples 1 and 2. This is considered to be due to the long wavelength shift of the plasmon resonance wavelength.

  From the results of this experimental example, even when the refractive index of the light transmitting layer is 1.64, the shape of the metal fine structure is anisotropic in the region of d1 / d2> 1 (that is, d1 /> d2). It has been found that a higher degree of electric field enhancement can be obtained than in the case of non-shaped metal microstructures. It was also found that a higher degree of electric field enhancement can be obtained when d1 / d2 is 1.5 or more and 4.5 or less, and a further higher degree of electric field enhancement can be obtained when d1 / d2 is 2 or more and 4 or less .

  In addition, it was also found that a high degree of electric field enhancement can be obtained at d1 / d3> 1.1 or more for the height (d3) of the metal microstructure. Furthermore, it can be seen from Table 4 that a higher degree of electric field enhancement can be obtained in the case of d1> d3> d2 than in the case of d1> d2> d3.

  In each of the above experimental examples, an elliptic cylinder is assumed as the shape of the metal fine structure, but d1, d2 and d3 can be defined, and any shape may be used as long as it has anisotropy. For example, the shape may be a combination of a spheroid rotated about the major axis of an ellipse (in this case, the major axis is d1), a cigar type, a needle shape, a rod shape, an indeterminate shape, and the like.

  From the above experimental examples, it was found that by appropriately selecting d1, d2 and d3, it is possible to realize a structure having a strong enhanced electric field without causing an increase in resonant wavelength.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the invention includes configurations substantially the same as the configurations described in the embodiments (for example, configurations having the same function, method and result, or configurations having the same purpose and effect). The present invention also includes configurations in which nonessential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that can achieve the same effects or the same objects as the configurations described in the embodiments. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... board | substrate, 10 ... metal layer, 20 ... light transmission layer, 30 ... metal fine structure layer, 40 ... metal fine structure, 41 ... metal fine structure row, 100 ... electric field enhancing element, 110 ... gas sample holding part, 112 ... Cover, 113: suction port, 114: suction flow channel, 115: dust removal filter, 116: discharge flow channel, 117: suction mechanism, 118: discharge port, 120: detection unit, 122a, 122b, 122c, 122d, lens, 124 ... Half mirror, 126 ... filter, 127 ... spectroscope, 128 ... light receiving element, 130 ... control unit, 132 ... detection control unit, 134 ... power control unit, 136 ... connection unit, 140 ... housing, 200 ... Raman spectroscopy device , 210: light source, 220: light detector, 300: electronic device, 310: arithmetic unit, 320: storage unit, 330: display unit

Claims (7)

A metal layer, a light transmitting layer provided on the metal layer and transmitting excitation light, and a second light emitting layer provided on the light transmitting layer, arranged at a first pitch in a first direction, and crossing the first direction An electric field enhancing element comprising a plurality of metal microstructures arranged at a second pitch in a direction;
A light source for irradiating the electric field intensifying element with the linearly polarized light polarized in the first direction as the excitation light;
A detector for detecting light emitted from the electric field enhancing element;
Equipped with
The arrangement of the metal microstructures of the electric field enhancing element satisfies the relationship of the following formula (1),
P1 <P2 ≦ Q + P1 (1)
[Here, P1 is the first pitch, P2 is the second pitch, and Q is the angular frequency of the localized plasmon excited in the row of the metal fine structure ω, and the metal constituting the metal layer The dielectric constant is ε (ω), the dielectric constant around the metal microstructure is ε, the speed of light in vacuum is c, the irradiation angle of the excitation light is θ, and the inclination angle from the thickness direction of the metal layer is θ, Represents the pitch of the diffraction grating that satisfies the following formula (2).
(.Omega. / C). {. Epsilon..epsilon. (. Omega.) / (. Epsilon. +. Epsilon. (. Omega.)) ^1/2 = .epsilon.1 ^{/ 2} (.omega. / C) .sin .theta. + 2a.pi. / Q (a =. ± .1 ,. ± .2 ,,) ... (2)]
The analyzer which satisfy | fills the relationship of d1> d2, when the dimension of the said 1st direction of the said metal fine structure and the said 2nd direction is each set to d1 and d2. In claim 1,
The excitation light includes light of a wavelength of 620 nm to 650 nm,
The analyzer which satisfy | fills the relationship of 1.1 <(d1 / d3) when the dimension of the 3rd direction which cross | intersects the said 1st direction of the said metal fine structure and the said 2nd direction is set to d3. In claim 1 or claim 2,
The analyzer according to claim 1, wherein a refractive index of the light transmitting layer is 1.4 or more and 1.7 or less. In any one of claims 1 to 3,
When a dimension of a third direction intersecting the first direction and the second direction of the metal microstructure is d3
An analyzer that satisfies the relationship d1>d3> d2. In any one of claims 1 to 4,
When a dimension of a third direction intersecting the first direction and the second direction of the metal microstructure is d3
d3 is an analyzer between 30 nm and 50 nm. In any one of claims 1 to 4,
The material of the light transmitting layer is silicon oxide or aluminum oxide.   An analyzer according to any one of claims 1 to 6, an operation unit which calculates health care information based on detection information from the detector, and a storage unit which stores the health care information. An electronic device comprising: a display unit for displaying the health care information.