Surface enhanced raman scattering spectral instrument and spectral electrolysis cell for surface enhanced raman scattering measurement

Abstract

To provide a surface enhanced Raman scattering spectral instrument that does not require material destruction processing on a measurement object, and can prevent inhibition of the movement of electrochemical reaction species from the inside of an electrolytic solution to a surface of an electrode, and a spectral electrolysis cell for surface enhanced Raman scattering measurement used for the same.SOLUTION: A surface enhanced Raman scattering spectral instrument 1 comprises: a light source LS that emits excitation light L1; a spectral electrolysis cell 10 for surface enhanced Raman scattering measurement; and a light receiving unit D that receives surface enhanced Raman scattering light L2, and the spectral electrolysis cell 10 for surface enhanced Raman scattering measurement has a container 11 that stores an electrolytic solution 13 including electrochemical reaction species, a plasmon sensor 16 to be a window part, a counter electrode 18 and a working electrode 19, and a power supply unit 22. The plasmon sensor 16 has a substrate 14 and modified metal nanoparticles 15 on one surface of the substrate 14. The working electrode 19 is held to be in point contact with the modified surfaces of the metal nanoparticles 15, and makes the excitation light L1 incident to excite surface plasmon on the metal nanoparticles 15 to generate the surface enhanced Raman scattering light L2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a surface-enhanced Raman scattering spectroscopic device and a spectroelectrolysis cell for surface-enhanced Raman scattering measurement. [Background technology]

[0002] Surface-enhanced Raman scattering spectroscopy is a method for obtaining, with high selectivity, a Raman spectrum that reflects the chemical structure of molecules present in the region where the electric field is enhanced, by utilizing the electric field enhancement effect induced in the immediate vicinity of the surface of a metal nanostructure by irradiating the structure with light of a specific wavelength. There are various methods that can be applied to use this spectroscopy in actual analysis, one of which is a method that uses a so-called plasmon sensor. There are several types of plasmon sensors, and for example, they are configured by modifying the surface of a light-transmitting material such as glass with metal nanoparticles.

[0003] When using the plasmon sensor of the above configuration in surface-enhanced Raman scattering spectroscopy, the plasmon sensor is placed on the object to be measured so that one side of the plasmon sensor modified with metal nanoparticles is in contact with the surface of the object to be measured, and an excitation laser is irradiated to the contact portion between the plasmon sensor and the surface of the object to be measured to induce an electric field enhancement at the interface, thus obtaining a surface-enhanced Raman scattering spectrum. According to surface-enhanced Raman scattering spectroscopy using a plasmon sensor, it is possible to measure surface-enhanced Raman scattering light without involving material-destructive treatment such as modifying the surface of the object to be measured with nanoparticles.

[0004] Patent Document 1 discloses an optical device that uses a plasmon sensor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6179905 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when using a plasmon sensor on an electrode surface placed in an electrolyte containing electrochemically reactive species, the plasmon sensor must be placed on the electrode surface, and the sensor itself inhibits the movement of electrochemically reactive species from the electrolyte to the electrode surface, which is essential for the reaction. As a result, the reaction environment on the electrode surface cannot be accurately reproduced, making it difficult to track the correct reaction behavior.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a surface-enhanced Raman scattering spectroscopic device that does not require material-destructive treatment of the electrode surface to be measured, and that is capable of tracking reaction behavior by reproducing a more ideal electrode environment by suppressing inhibition of the migration of electrochemical reaction species to the electrode surface, and a spectroelectrolysis cell for surface-enhanced Raman scattering measurement used therefor. [Means for solving the problem]

[0008] The surface-enhanced Raman scattering spectroscopic device according to the present invention is a surface-enhanced Raman scattering spectroscopic device for measuring surface-enhanced Raman scattered light, and includes a light source that emits excitation light, a spectroelectrolysis cell for surface-enhanced Raman scattering measurement, and a light receiving unit that receives the surface-enhanced Raman scattered light from inside the spectroelectrolysis cell for surface-enhanced Raman scattering measurement when the excitation light is incident on the spectroelectrolysis cell for surface-enhanced Raman scattering measurement. The spectroelectrolysis cell for surface-enhanced Raman scattering measurement includes a container for accommodating an electrolyte solution containing electrochemically reactive species, a plasmon sensor provided in the container as a window portion that transmits the excitation light and the surface-enhanced Raman scattered light, a counter electrode and a working electrode for passing a current through the electrolyte solution so as to electrochemically react the electrochemically reactive species, and a light receiving unit that receives the current through the counter electrode and the working electrode. and a power supply unit that supplies a current between the working electrode and the excitation light, the plasmon sensor having a substrate that transmits the excitation light and the surface-enhanced Raman scattered light, and metal nanoparticles modified on one surface of the substrate on the inside of the spectroelectrolysis cell for surface-enhanced Raman scattering measurement, the working electrode being held in the container so as to be in point contact with the surface modified with the metal nanoparticles, and with the surface modified with the metal nanoparticles in point contact with the working electrode, the excitation light is incident from the other surface side of the substrate toward the one surface side to excite surface plasmons on the surfaces of the metal nanoparticles in contact with the working electrode, and the surface plasmons are enhanced by the Raman scattered light that reflects the state and reaction behavior of the electrochemical reaction species on the working electrode to generate the surface-enhanced Raman scattered light.

[0009] The spectroelectrolysis cell for surface-enhanced Raman scattering measurement according to the present invention is a spectroelectrolysis cell for surface-enhanced Raman scattering measurement for measuring surface-enhanced Raman scattered light when excitation light is incident thereon, and includes a container for accommodating an electrolyte solution containing electrochemically reactive species, a plasmon sensor provided in the container as a window portion for transmitting the excitation light and the surface-enhanced Raman scattered light, a counter electrode and a working electrode for passing a current through the electrolyte solution so as to electrochemically react the electrochemically reactive species, and a power supply unit for passing the current between the counter electrode and the working electrode, and the plasmon sensor transmits the excitation light and the surface-enhanced Raman scattered light. The spectroelectrolysis cell for surface-enhanced Raman scattering measurement has a substrate and metal nanoparticles modified on one surface of the substrate on the inner side thereof, and the working electrode is held in the container so as to be in point contact with the surface modified with the metal nanoparticles. With the surface modified with the metal nanoparticles in point contact with the working electrode, the excitation light is incident from the other surface side of the substrate toward the one surface side to excite surface plasmons on the surfaces of the metal nanoparticles in contact with the working electrode, and the surface plasmons are amplified by the Raman scattered light reflecting the state and reaction behavior of the electrochemical reaction species on the working electrode to generate the surface-enhanced Raman scattered light. Effect of the Invention

[0010] According to the present invention, there is no need for material-destructive treatment of the electrode surface to be measured, and it is possible to track reaction behavior by reproducing a more ideal electrode environment by suppressing inhibition of the migration of electrochemically reactive species from the electrolyte to the electrode surface. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of a surface-enhanced Raman scattering spectroscopic device according to an embodiment. [Diagram 2] FIG. 4 is a diagram showing a current versus potential of a working electrode in an electrochemical reaction according to an embodiment. [Diagram 3] FIG. 2 is a diagram showing a Raman spectrum in the vicinity of 1090 cm −1 according to an embodiment. [Figure 4] FIG. 2 is a diagram showing a Raman spectrum in the vicinity of 1850 cm −1 according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] (Surface-enhanced Raman scattering spectrometer 1) 1 is a schematic diagram of a surface-enhanced Raman scattering spectrometer 1 according to an embodiment. The surface-enhanced Raman scattering spectrometer 1 has a light source LS that emits excitation light L1, a spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement, and a light receiving unit D that receives surface-enhanced Raman scattered light L2 from the inside of the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement when the excitation light L1 is incident on the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement. The surface-enhanced Raman scattering spectrometer 1 is a surface-enhanced Raman scattering spectrometer that measures surface-enhanced Raman scattered light that reflects the state and reaction behavior of electrochemical reaction species on a working electrode 19 contained in an electrolyte contained in the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement.

[0014] (Spectroelectrochemical cell for surface-enhanced Raman scattering measurements 10) The spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement includes a container 11 that contains an electrolyte 13 containing electrochemically reactive species, a plasmon sensor 16, a counter electrode 18 and a working electrode 19 for passing a current through the electrolyte 13 so as to electrochemically react the electrochemically reactive species, and a power supply unit 22 for passing a current between the counter electrode 18 and the working electrode 19. The cell also includes a reference electrode 21 that serves as a reference for measuring the potential of the working electrode 19 in order to control the potential of the working electrode 19.

[0015] (Container 11) The container 11 contains an electrolyte 13 containing electrochemically reactive species. The container 11 is configured to include a lid 12 so as to be able to seal the inside. The container 11 and the lid 12 are formed of a chemically resistant resin such as polyether ether ketone, and may each be formed of a plurality of members via a sealant or the like as necessary. A protective part 17 is provided on the surface of the lid 12 opposite the container 11, but depending on the design, the lid 12 may be integrated with the protective part 17. The protective part 17 is formed of a chemically resistant resin such as polyether ether ketone.

[0016] (Electrolyte 13) The electrolytic solution 13 contains electrochemically reactive species. The electrochemically reactive species are not particularly limited, but contain ethylene carbonate and LiPF6 in the embodiment described later.

[0017] (Plasmon Sensor 16) The plasmon sensor 16 is provided in the lid 12 constituting the container 11 as a window through which the excitation light L1 and the surface-enhanced Raman scattered light L2 pass. The plasmon sensor 16 has a substrate 14 through which the excitation light L1 and the surface-enhanced Raman scattered light L2 pass, and metal nanoparticles 15 modified on one surface of the substrate 14 on the inner side of the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement.

[0018] (Base 14) The substrate 14 is made of, for example, transparent quartz glass so that the excitation light L1 and the surface-enhanced Raman scattered light L2 can pass through it.

[0019] (Metal Nanoparticles 15) The metal nanoparticles 15 are disposed on one surface of the substrate 14 on the inner side of the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement. The metal nanoparticles 15 contact the electrolyte 13 inside the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement. The metal nanoparticles 15 are formed of, for example, Ag, Au, or Cu, and are preferably formed of Ag. The metal nanoparticles 15 are formed, for example, in a hemispherical shape having a flat surface on a part of the surface and a curved surface. The flat surface of the metal nanoparticles 15 is fixed to one surface of the substrate 14 in surface contact. The metal nanoparticles 15 bulge out from one surface of the substrate 14 and are provided so as to be in close contact with the working electrode 19 described later. As a result, when excitation light L1 is irradiated from the other side opposite to one side of the substrate 14 toward one side, surface plasmons are excited on the surface of the metal nanoparticles 15 in contact with the working electrode 19, and the electric field of these surface plasmons (also simply referred to as the plasmon electric field) produces surface-enhanced Raman scattering light L2 that reflects the state and reaction behavior of the electrochemically reactive species on the working electrode 19 in the vicinity of the surface of the metal nanoparticles 15 in contact with the working electrode 19.

[0020] The diameter of the metal nanoparticles 15, when assumed to be spherical, is preferably 5 nm to 100 nm, more preferably 16 nm to 60 nm, and even more preferably 30 nm to 50 nm. Here, the metal nanoparticles 15 are, for example, hemispherical as described above, and the "diameter when assumed to be spherical" is the diameter of a sphere having a full spherical surface obtained by complementing the curved surface of the hemisphere.

[0021] Although the metal nanoparticles 15 are described above as being hemispherical, the shape is not limited thereto and may be, for example, conical. A configuration may be adopted in which a part of the spherical metal nanoparticles 15 is embedded in the substrate 14 and the hemispherical part of the metal nanoparticles 15 is exposed. The metal nanoparticles 15 may be covered with a coating film formed of a material having higher abrasion resistance than the substrate 14. Alternatively, the metal nanoparticles 15 may be covered with a coating film formed of a material having a higher refractive index than the substrate 14.

[0022] As the plasmon sensor 16, in addition to the above, the optical device described in Patent Document 1 can be preferably used.

[0023] (opposite 18) The counter electrode 18 is made of a metal foil and is attached to the surface of the lid 12 facing the container 11 so as to be in contact with the electrolyte 13. The counter electrode 18 is made of, for example, Pt foil. The counter electrode 18 is made of a material that does not react with electrochemically reactive species that serve as main reactants contained in the electrolyte 13. The counter electrode 18 does not necessarily have to be attached to the lid 12 as long as it is fixed in a manner that does not allow it to come into contact with the working electrode 19 or the reference electrode 21.

[0024] (Working electrode 19) The working electrode 19 is formed of a wire-shaped metal and is held in the container 11 so as to be in point contact with the surface of at least one metal nanoparticle. The working electrode 19 is formed of, for example, a Cu wire. The wire-shaped working electrode 19 is disposed so as to penetrate the bottom of the container 11 and contact the electrolyte 13 at the middle of the working electrode 19, and both ends extend from the bottom of the container 11 to the outside of the container 11. The working electrode 19 may be formed of a material that reacts with the electrochemically reactive species of the electrolyte 13, and working electrodes 19 made of various materials can be used. A working electrode protective cover 20 is provided around the working electrode 19 in a portion including the portion where the working electrode 19 penetrates the container 11. The working electrode protective cover 20 defines the area where the working electrode 19 contacts the electrolyte 13.

[0025] (Reference pole 21) The reference electrode 21 has a shape extending in one direction, such as a rod shape, with one end in contact with the electrolyte 13 and the other end penetrating the side of the container 11 and extending to the outside of the container 11. For example, a Li-Al electrode or the like can be used as the reference electrode 21. The reference electrode 21 is an electrode that indicates a reference value when measuring the potential of another electrode, and this makes it possible to measure and control the potential applied to the working electrode 19 during an electrochemical reaction.

[0026] (Power supply section 22) The power supply unit 22 is electrically connected to the counter electrode 18, the working electrode 19, and the reference electrode 21, and determines the potential of each electrode.

[0027] (Light source LS) The light source LS emits excitation light L1. The excitation light L1 enters the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement through the plasmon sensor 16, which is a window portion. As the light source LS, for example, a solid-state laser that emits light with a wavelength of 532 nm to 1500 nm, specifically 532 nm, 785 nm, or 1060 nm, can be used. Preferably, a laser with a wavelength according to the metal species of the metal nanoparticles of the plasmon sensor to be used or the size of the metal nanoparticles is used.

[0028] (Light receiving part D) The light receiving unit D receives surface-enhanced Raman scattered light L2 from inside the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement when the excitation light L1 is incident on the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement. The light receiving unit D is composed of, for example, an imaging element equipped with a spectroscopic function. The light receiving unit D and the light source LS are arranged perpendicular to each other with the half mirror HM at the center, and the surface-enhanced Raman scattered light L2 is configured to enter the light receiving unit D with its traveling direction bent by the half mirror HM.

[0029] (others) On the optical path of the excitation light L1 and the optical path of the surface-enhanced Raman scattering light L2, optical members generally used in optical paths, such as an objective lens, a pinhole, an optical filter, etc., may be arranged as necessary. In order to adjust the optical arrangement of the excitation light L1 with respect to the surface-enhanced Raman scattering measurement spectroelectrolytic cell 10, the surface-enhanced Raman scattering measurement spectroelectrolytic cell 10 may be provided on a piezo stage capable of moving the surface-enhanced Raman scattering measurement spectroelectrolytic cell 10 in three axial directions, so that the focal position of the excitation light L1 can be adjusted in the surface direction and the depth direction in Å (angstrom) units.

[0030] In the surface-enhanced Raman scattering spectrometer 1 using the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement having the plasmon sensor 16 and working electrode 19 configured as described above, excitation light L1 is incident from the other side to one side of the substrate 14 with the metal nanoparticles 15 in point contact with the working electrode 19, exciting surface plasmons on the surfaces of the metal nanoparticles 15 in contact with the working electrode 19, and the surface plasmons enhance the Raman scattered light reflecting the state and reaction behavior of the electrochemical reaction species on the working electrode 19 to generate surface-enhanced Raman scattered light L2. The electric field enhancement effect due to the excitation of the surface plasmons extends to the area near the surface of the metal nanoparticles 15 in contact with the working electrode 19, realizing highly sensitive Raman spectroscopy in which the electric field is enhanced by the surface plasmons.

[0031] When Raman scattering spectroscopy is performed in the surface-enhanced Raman scattering spectroscopy device 1 having the above-described configuration in which the electrolyte 13 contains ethylene carbonate and the working electrode 19 is formed of Cu, it is possible to track electrolyte decomposition products that are generated within a nm-order range near the surface of an electrode used in a metal lithium secondary battery.

[0032] (Method of manufacturing plasmon sensor 16) Plasmon sensor 16 can be manufactured by creating metal nanoparticles 15 on a substrate 14 made of transparent quartz glass using, for example, a sputtering method, metal plating method, vapor deposition method, CVD (Chemical Vapor Deposition) method, or the like, either alone or in combination.

[0033] (Action and effect) In the surface-enhanced Raman scattering spectroscopic device 1 using the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement having the plasmon sensor 16 and the working electrode 19 of the above configuration, surface plasmons are excited on the surface of the metal nanoparticles 15 in contact with the working electrode 19, and the surface plasmons enhance the Raman scattered light reflecting the state and reaction behavior of the electrochemical reaction species on the working electrode 19 to generate surface-enhanced Raman scattered light L2. Since the above plasmon sensor 16 is used, there is no need to perform material destruction treatment on the electrode surface to be measured. In addition, since the plasmon sensor 16 and the working electrode 19 are in point contact, the inhibition of the movement of the electrochemical reaction species from the electrolyte 13 to the electrode surface is suppressed, and it is possible to track the reaction behavior more accurately while reproducing the environment of an ideal electrode reaction field close to the original environment. In this way, the highly sensitive Raman spectroscopy by the spectroelectrolysis cell 10 for surface-enhanced Raman scattering measurement having the plasmon sensor 16 allows the electrochemical reaction to be tracked in situ by non-destructive measurement without providing nanoparticles on the electrode.

[0034] (Example) Using the surface-enhanced Raman scattering spectrometer 1 described in the above embodiment, electrolyte decomposition products occurring in a nm-order range near the electrode surface used in a metal lithium secondary battery were observed. In the surface-enhanced Raman scattering spectrometer 1, a Cu wire was used as the working electrode 19, and an electrolyte 13 containing ethylene carbonate and LiPF6 was used. The potential of the working electrode 19 was changed from +2.1 V to -0.6 V, and the formation of Li2CO3 and Li2C2 at this time was observed using the Raman scattering spectrum (Li2CO3: 1090 cm -1 , Li2C2: 1850cm -1 ) was traced.

[0035] FIG. 2 is a diagram showing the current flowing between the counter electrode 18 and the working electrode 19 with respect to the potential of the working electrode 19 in the electrochemical reaction according to the embodiment. In FIG. 2, the horizontal axis represents the potential (V) of the working electrode with respect to the reference electrode (Li-Al electrode), and the vertical axis represents the current (10 -3 When the potential of the working electrode 19 is changed from +2.1 V to −0.6 V, decomposition of the electrolyte 13 occurs from about +2.0 V, and Li precipitates from about −0.2 V.

[0036] FIG. 3 shows the change in potential of the working electrode 19 according to the embodiment from +2.1 V to −0.6 V. -1 The figure shows the Raman spectrum of the nearby region. The Raman shift is 1090 cm -1 The peak near corresponds to Li2CO3. Li2CO3 is gradually formed when the potential of the working electrode 19 starts from +1.4 V, and is then consumed from +0.3 V. This corresponds to when the potential of the working electrode 19 in FIG. 2 changes from +1.4 V to +0.3 V.

[0037] The reaction formula when the potential of the working electrode 19 changes from +1.4 V to +0.3 V is shown below.

[0038] [ka]

[0039] FIG. 4 shows the change in potential of the working electrode 19 according to the embodiment from +2.1 V to −0.6 V. -1 The figure shows the Raman spectrum of the nearby region. The Raman shift is 1850 cm -1 The peak near corresponds to Li2C2. Li2C2 can be formed starting from Li2CO3, and this corresponds to the fact that Li2CO3 is consumed at around +0.3 V, as seen in Figure 3, while Li2C2 begins to be observed at +0.4 V, which is almost the same potential as the consumption position of Li2CO3.

[0040] The reaction formula in the potential region where the potential of the working electrode 19 is lower than +0.4 V is shown below.

[0041] [ka]

[0042] The above examples demonstrate that it is possible to observe electrolyte decomposition products occurring in the nm-order range near the surface of an electrode used in a metallic lithium secondary battery.

[0043] The present invention is not limited to the above-mentioned embodiment, and various modifications are possible within the scope of the present invention, and other embodiments and modifications made by those skilled in the art are also included in the present invention. For example, the container 11 can be filled with an inert gas, a catalytic metal wire can be substituted for the working electrode 19, a gas as a reactive species can be continuously supplied to contact the catalytic metal wire, and a product produced by the catalytic reaction can be detected, making it possible to track the reaction in the gas in situ. [Explanation of symbols]

[0044] 1. Surface-enhanced Raman scattering spectrometer 10. Spectroelectrochemical cell for surface-enhanced Raman scattering measurements 11 Container 12 Lid 13 Electrolyte 14 Base 15 Metal Nanoparticles 16 Plasmon Sensor 17 Protection Department 18 Opposite 19 Working electrode 20 Working electrode protective cover 21 Reference pole 22 Power supply section LS light source L1 excitation light L2 Surface-enhanced Raman scattering HM Half Mirror D Light receiving section

Claims

1. A surface-enhanced Raman scattering spectroscopic device for measuring surface-enhanced Raman scattered light, comprising: A light source that emits excitation light; A spectroelectrolytic cell for surface-enhanced Raman scattering measurement; a light receiving unit that receives the surface-enhanced Raman scattered light from inside the surface-enhanced Raman scattering measurement spectroelectrolysis cell when the excitation light is incident on the surface-enhanced Raman scattering measurement spectroelectrolysis cell, The surface-enhanced Raman scattering spectroelectrolysis cell comprises: a vessel containing an electrolyte solution containing electrochemically reactive species; a plasmon sensor provided in the container as a window portion that transmits the excitation light and the surface-enhanced Raman scattered light; a counter electrode and a working electrode for passing a current through the electrolyte so as to electrochemically react the electrochemically reactive species; a power supply unit that causes the current to flow between the counter electrode and the working electrode, The plasmon sensor includes: a substrate that transmits the excitation light and the surface-enhanced Raman scattered light; and metal nanoparticles modified on one surface of the substrate on the inner side of the surface-enhanced Raman scattering measurement spectroelectrolysis cell; the working electrode is held in the container so as to be in point contact with the surface modified with the metal nanoparticles; With the surface modified with the metal nanoparticles in point contact with the working electrode, the excitation light is incident from the other surface side of the substrate toward the one surface side to excite surface plasmons on the surfaces of the metal nanoparticles in contact with the working electrode, and the Raman scattered light reflecting the state and reaction behavior of the electrochemical reaction species on the working electrode is enhanced by the surface plasmons to generate the surface-enhanced Raman scattered light. Surface-enhanced Raman scattering spectrometer.

2. The metal nanoparticles have flat surfaces, and the flat surfaces are in surface contact with the one surface of the substrate so as to bulge from the one surface onto the substrate. The surface-enhanced Raman scattering spectroscopic apparatus according to claim 1 .

3. The diameter of the metal nanoparticles, when assumed to be spherical, is 5 nm or more and 100 nm or less. The surface-enhanced Raman scattering spectroscopic apparatus according to claim 2 .

4. The metal nanoparticles are hemispherical or conical. The surface-enhanced Raman scattering spectroscopic apparatus according to claim 1 .

5. The metal nanoparticles are made of Ag, Au, or Cu. The surface-enhanced Raman scattering spectroscopic apparatus according to claim 1 .

6. The metal nanoparticles are covered with a coating film formed of a material having higher abrasion resistance than the substrate. The surface-enhanced Raman scattering spectroscopic apparatus according to claim 1 .

7. The metal nanoparticles are covered with a coating film made of a material having a higher refractive index than the substrate. The surface-enhanced Raman scattering spectroscopic apparatus according to claim 1 .

8. The working electrode is disposed so as to penetrate the bottom of the container, come into contact with the electrolyte at a midpoint of the working electrode, and have both ends extending from the bottom of the container to the outside of the container. The surface-enhanced Raman scattering spectroscopic apparatus according to claim 1 .

9. A spectroelectrolysis cell for surface-enhanced Raman scattering measurement for measuring surface-enhanced Raman scattered light when excitation light is incident thereon, a vessel containing an electrolyte solution containing electrochemically reactive species; a plasmon sensor provided in the container as a window portion that transmits the excitation light and the surface-enhanced Raman scattered light; a counter electrode and a working electrode for passing a current through the electrolyte so as to electrochemically react the electrochemically reactive species; a power supply unit that causes the current to flow between the counter electrode and the working electrode, The plasmon sensor includes: a substrate that transmits the excitation light and the surface-enhanced Raman scattered light; and metal nanoparticles modified on one surface of the substrate on the inner side of the surface-enhanced Raman scattering measurement spectroelectrolysis cell; the working electrode is held in the container so as to be in point contact with the surface modified with the metal nanoparticles; With the surface modified with the metal nanoparticles in point contact with the working electrode, the excitation light is incident from the other surface side of the substrate toward the one surface side to excite surface plasmons on the surfaces of the metal nanoparticles in contact with the working electrode, and the Raman scattered light reflecting the state and reaction behavior of the electrochemical reaction species on the working electrode is enhanced by the surface plasmons to generate the surface-enhanced Raman scattered light. Spectroelectrochemical cell for surface-enhanced Raman scattering measurements.

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