Infrared spectroscopic sample stage

Abstract

To provide a sample support of infrared spectroscopic analysis on which a small amount of samples can be expanded in a thin and homogeneous manner in a sealed space.SOLUTION: The sample support of infrared spectroscopic analysis comprises: an optical element 10 including a sample arrangement surface 11 on which a sample X can be placed; a sample holding member 30 including a sample introduction hole 31 penetrating in a direction orthogonal to a surface direction of the sample arrangement surface; and a lid member 40 including a projection 42 projecting toward the sample arrangement surface and capable of fitting into the sample introduction hole. The optical element 10, the sample holding member 30 and the lid member 40 are overlapped on one another in this order. The sample introduction hole, the sample arrangement surface and a tip surface 42a of the projection form a sealed space. The tip surface 42a is configured to press the sample X encapsulated in the sealed space toward the sample arrangement surface 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a sample stage for use in infrared spectroscopy. [Background technology]

[0002] Infrared spectroscopy is an analytical technique for analyzing the structure and quantifying a sample by irradiating the material with infrared light and measuring the transmitted or reflected light. Conventionally, attempts have been made to perform highly sensitive measurements using as small a sample amount as possible in infrared spectroscopy.

[0003] For example, Patent Document 1 discloses a jig that is made up of a charged metal part and an insulating part so that infrared spectroscopy can be performed directly on the jig after sampling a minute sample. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Publication No. 2001-255263 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional infrared spectroscopy, the surface on which the sample is placed is open. Therefore, for example, if the sample is a radioactive material, the person performing the measurement may be exposed to external radiation from the radiation emitted by the sample. Furthermore, if the sample is small, it is difficult to spread it thinly and evenly over the sample placement surface, making it difficult to achieve the desired measurement sensitivity.

[0006] Therefore, an object of the present disclosure is to provide a sample stage for infrared spectroscopic analysis that is capable of spreading a small amount of sample thinly and uniformly in an enclosed space. [Means for solving the problem]

[0007] In order to solve the above problems, the first invention disclosed herein is a sample stage for use in infrared spectroscopic analysis, comprising: a receiving member having a sample placement surface on which a sample can be placed; a sample holding member having a sample introduction hole that penetrates in a direction intersecting the surface direction of the sample placement surface; and a lid member that protrudes toward the sample placement surface and has a protrusion that can fit into the sample introduction hole, wherein the receiving member, sample holding member, and lid member are stacked in this order, and an airtight space is formed by the sample introduction hole, the sample placement surface, and the tip surface of the protrusion, and the tip surface is configured to be able to press the sample sealed in the airtight space toward the sample placement surface.

[0008] According to this configuration, the sample introduction hole, the sample placement surface, and the tip surface of the protrusion form a sealed space, and the sample can be sealed in the sealed space. Therefore, for example, if the sample is a radioactive material, radiation emitted by the sample is prevented from leaking from the sample stage, enabling safe measurement. Furthermore, within the sample introduction hole, the tip surface of the protrusion presses the sample against the sample placement surface, allowing a small amount of sample to be spread evenly.

[0009] A second invention is characterized in that, in the first invention, the sample introduction hole is circular and the protrusion is cylindrical.

[0010] According to this configuration, it becomes easy to improve the machining precision of the sample stage, and it becomes possible to improve the airtightness of the sealed space.

[0011] A third invention is a sample stage used for infrared spectroscopic analysis of a liquid sample in the first or second invention, characterized in that the sample holding member has a groove portion on the outer periphery of the sample introduction hole on the surface facing the receiving member, and a sealing member is installed in the groove portion.

[0012] According to this configuration, by sealing the outer periphery of the sample introduction hole with a sealing member on the surface of the sample holding member facing the receiving member, it is possible to prevent the liquid sample from leaking from the sample stage.

[0013] A fourth invention is a sample stage used in total reflection absorption spectroscopy in any one of the first to third inventions, characterized in that it comprises a frame member that supports the receiving member, the receiving member being an optical element for total reflection, the sample placement surface being a total reflection surface, and the receiving member being installed on top of the frame member so that the sample placement surface is the upper surface.

[0014] With this configuration, the sample placement surface is a total reflection surface, so there are no restrictions on the material of the lid member. Furthermore, since the receiving member is installed so that the sample placement surface faces up, sample replacement becomes easy and measurement efficiency can be improved.

[0015] A fifth invention is any one of the first to fourth inventions, characterized in that a metal film is vapor-deposited on the sample placement surface.

[0016] According to this configuration, the sample placement surface is vapor-deposited with a metal film, which enhances the infrared absorption intensity and makes it possible to further increase the measurement sensitivity. [Effects of the Invention]

[0017] As described above, the present disclosure can provide a sample stage for infrared spectroscopic analysis that can spread a small amount of sample thinly and uniformly in an enclosed space. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing an example of an infrared spectroscopic analyzer using a sample stage according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view showing the sample stage of the present disclosure. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 5 is an end view of line VV in FIG. 4. [Figure 6] FIG. [Figure 7] FIG. [Figure 8]FIG. [Figure 9] FIG. 9 is an end view taken along line IX-IX in FIG. 8. [Figure 10] FIG. [Figure 11] 1 is a SEIRA spectrum of an americium sample measured using the sample stage of the present disclosure. [Figure 12] FIG. 10 is a schematic diagram showing another example of an infrared spectroscopic analyzer using the sample stage of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0020] The infrared spectroscopic sample stage of the present disclosure can be applied to various types of infrared spectroscopic analyzers that perform structural analysis and quantification of samples by irradiating a substance with infrared light and measuring the transmitted or reflected light. Below, an embodiment will be described in which the sample stage is applied to surface-enhanced infrared absorption spectroscopy, which combines total internal reflection absorption measurement with a metal thin film.

[0021] [Configuration of infrared spectrometer] As shown in FIG. 1, in an infrared spectroscopic analyzer 100 using the sample stage 1 of this embodiment, infrared light emitted from an IR light source 60 is reflected by mirrors 61a and 61b and made incident at a predetermined angle of incidence on an optical element 10 for total reflection on which a sample X is placed, and the reflected light emitted from the optical element 10 is reflected by mirrors 61c and 61d and introduced into a detector 62.

[0022] [Attenuated total reflection absorption measurement method] In total reflection absorption measurement, when infrared light is incident from a material with a large refractive index, i.e., the total reflection optical element 10 in the sample stage 1 of the present disclosure, to a material with a small refractive index, i.e., sample X, at an angle of incidence greater than the critical angle, the infrared light is totally reflected. Microscopically, the infrared light does not reflect at the interface, but penetrates a certain depth into sample X before being totally reflected. In this case, the reflectance is 1 in the wavenumber region where there is no absorption on the sample side, but in the wavenumber region where there is absorption, the reflectance is attenuated and becomes less than 1. By introducing such reflected light into a detector and analyzing the absorption spectrum, it is possible to detect and identify chemical species.

[0023] [Surface-enhanced infrared absorption spectroscopy] In total internal reflection absorption spectroscopy, a measurement method in which a metal film is formed between the optical element 10 and the sample X is called surface-enhanced infrared absorption spectroscopy (SEIRA spectroscopy). In surface-enhanced infrared absorption spectroscopy, the metal particles that make up the metal film exhibit special absorption due to the excitation of localized plasmons in the visible light range to near-infrared light range. A strong surface electric field is generated around the metal particles in which plasmons are excited.

[0024] The polarization of metal particles excited by the infrared light electric field creates an electric field around the metal particles. The excited electric field occurs near the surface of the metal film, perpendicular to the surface of the nanostructure of the metal particles, and therefore vibrations with an oscillating dipole moment parallel to the electric field, i.e., perpendicular to the surface of the metal film, are selectively observed.

[0025] The vibrational dipole moment of molecules induced by the surface electric field perturbs the polarization of metal particles. This perturbation occurs at the vibrational frequency of the molecules, so the molecular vibrations are observed superimposed on the absorption of the metal particles. Since the change in the absorption of the metal caused by the vibration of the adsorbed molecules is much larger than that in the absence of the metal, surface-enhanced infrared absorption spectroscopy can observe the molecular vibrations via the absorption of the metal particles, allowing the metal particles to act as an amplifier of infrared absorption.

[0026] [Configuration of sample stage] In the sample stage 1 used in surface-enhanced infrared absorption spectroscopy, the "receiving member" described in the claims is an optical element 10 for total reflection. As shown in Figure 1, the sample stage 1 is installed at the top of an infrared spectroscopic analysis device 100, between an IR light source 60 and a detector 62.

[0027] 2, the sample stage 1 includes an optical element 10 having a sample placement surface 11 on which a sample X can be placed, a frame member 20 that supports the optical element 10, a sample holding member 30 having a sample introduction hole 31 that penetrates in a direction intersecting the surface direction of the sample placement surface 11, and a cover member 40 that protrudes toward the sample placement surface 11 and has a protrusion 42 that can fit into the sample introduction hole 31. The frame member 20, optical element 10, sample holding member 30, and cover member 40 are stacked in this order from the bottom up.

[0028] The optical element 10 has a sample placement surface 11 that is a total reflection surface, and is installed on top of the frame member 20 so that the sample placement surface 11 is the upper surface. The shape of the optical element 10 is not limited, and any shape commonly used in infrared spectroscopic analysis can be used. For example, a triangular prism as shown in Figures 1 and 2 is preferable, but a trapezoidal or hemispherical shape may also be used. The optical element 10 can be made of a material such as silicon or germanium.

[0029] A metal film 70 is preferably vapor-deposited on the sample placement surface 11. By forming the metal film 70 between the optical element 10 and the sample X and performing measurements by surface-enhanced infrared absorption spectroscopy, it becomes possible to increase the measurement sensitivity. The metal film 70 is made of, for example, gold, silver, copper, platinum, etc. The metal film 70 can be formed by a known method such as vacuum deposition or electroless plating.

[0030] The frame member 20 is a rectangular plate-like member shown in Figures 3 to 6. The material of the frame member 20 is not limited, but it can be made of, for example, stainless steel, alumina, duralumin or the like.

[0031] A rectangular installation hole 21 is formed in the approximate center of the frame member 20, penetrating through the thickness of the frame member 20. Locking pieces 22, 22 are formed on two opposing sides of the installation hole 21, protruding toward the inside of the installation hole 21. The two locking pieces 22, 22 are inclined downward so as to approach each other.

[0032] The optical element 10 is installed in the installation hole 21. The installation hole 21 is formed to be approximately the same size as the optical element 10, but the optical element fitted into the installation hole 21 from above can be locked by locking pieces 22, 22 and held in the installation hole 21. The optical element 10 is exposed below the installation hole 21, and infrared light can be made to enter from below the installation hole 21 and reflected downward.

[0033] The frame member 20 has four screw holes 23 formed around the outer periphery of the installation hole 21, and is screwed together with a sample holding member 30 (described later) through the screw holes 23. On the bottom surface of the frame member 20, ribs 24, 24 extending in the longitudinal direction and protruding downward are formed facing each other across the installation hole 21. The ribs 24, 24 play a role in positioning the sample stage 1 when it is placed at a predetermined position in the infrared spectroscopic analysis device 100.

[0034] The sample holding member 30 is a rectangular plate-shaped member as shown in Figures 7 to 9. There are no restrictions on the material of the sample holding member 30, but it is preferably made of a resin with high chemical resistance, such as Teflon (registered trademark).

[0035] A circular sample introduction hole 31 is formed in approximately the center of the sample holding member 30, penetrating in a direction intersecting the planar direction of the sample placement surface 11, i.e., in the thickness direction of the sample holding member 30. When the sample holding member 30 and the frame member 20 are stacked together, the sample introduction hole 31 is located above the installation hole 21 and approximately in the center of the optical element 10. The size of the sample introduction hole 31 is smaller than the top surface of the optical element 10.

[0036] Four screw holes 32 are provided on the top surface of the sample holding member 30 at positions facing the screw holes 23 of the frame member 20. A ring-shaped groove 33 is formed on the outer periphery of the sample introduction hole 31 on the bottom surface of the sample holding member 30, i.e., the surface facing the optical element 10.

[0037] A seal member 50 is installed in the groove 33. The seal member 50 is an elastic member such as an O-ring. When the sample holding member 30 is attached on top of the optical element 10, the seal member 50 installed in the groove 33 abuts against the upper surface of the optical element 10. For example, if the sample X is powdery, it is not necessarily necessary to use the seal member 50, but if the sample X is liquid, it is preferable to use the seal member 50 to prevent leakage.

[0038] 2 and 10, the cover member 40 has a rectangular plate-shaped base 41 and a cylindrical protrusion 42 formed so as to protrude downward from approximately the center of the bottom surface of the base 41 toward the sample placement surface 11. The protrusion 42 can be fitted into the sample introduction hole 31. It is preferable that the outer diameter of the protrusion 42 and the inner diameter of the sample introduction hole 31 are approximately the same so that the protrusion 42 can be fitted into the sample introduction hole 31 without any gaps.

[0039] The material of the cover member 40 is not limited, but a resin with high chemical resistance is preferable, and it can be made of Teflon (registered trademark), for example. It is preferable to use a sample holding member 30 and a cover member 40 molded from the same material. If they are made of the same material, differences in shrinkage due to temperature changes are unlikely to occur, and it is possible to more reliably maintain the airtightness between the sample introduction hole 31 and the protrusion 42.

[0040] The length of the protrusion 42 is at least the same as the length of the sample introduction hole 31, and a flat tip surface 42a is formed at the tip of the protrusion 42. The tip surface 42a is approximately parallel to the sample placement surface 11 of the optical element 10. When the frame member 20, the optical element 10, the sample holding member 30, and the cover member 40 are assembled in this order from below, the sample introduction hole 31, the sample placement surface 11, and the tip surface 42a form an enclosed space, and the tip surface 42a can press the sample X sealed in the enclosed space toward the sample placement surface 11.

[0041] <Example> Next, the measurement procedure and results will be described for measuring an americium complex, which is a radioactive substance, as the sample X by surface-enhanced infrared absorption spectroscopy using the sample stage 1 of this embodiment.

[0042] [Sample preparation] The americium sample used for sample X is an americium-DGA complex with a DGA (diglycolamide) ligand. This americium sample (Commissariat A L'Energie Atomique, Code No. Am-243-S) was dissolved in a nitric acid aqueous solution of unknown concentration. The americium sample was evaporated to dryness to prepare a nitric acid aqueous solution of adjusted concentration. The americium sample was placed in a PFA vial and heated on a hot plate at 150°C for 20 minutes to solidify. The solidified americium sample was then redissolved in a 1M nitric acid aqueous solution to create sample X.

[0043] [Measurement method] A triangular silicon prism was prepared as the optical element 10, and gold was deposited on the sample placement surface 11 by vacuum deposition using resistance heating to form a 4 nm thick metal film 70. The frame member 20 was made of stainless steel, the sample holding member 30 was made of Teflon (registered trademark), and the sample introduction hole 31 had a diameter of 10 mm. The cover member 40 was made of transparent glass so that it could be visually confirmed that the sample X was spread thinly and uniformly by the tip surface 42a.

[0044] The frame member 20, optical element 10, and sample holder 30 were stacked in this order, and screws 80 were inserted into the screw holes 23 and 32 to fix the frame member 20 and the sample holder 30. The sample stage 1 prepared in this manner was placed in a predetermined position in the infrared spectrometer 100. The infrared spectrometer 100 used was an FT / IR-4200 manufactured by JASCO Corporation equipped with a VeeMAX III manufactured by PIKE Technologies as a reflection accessory, and measurements were performed by placing the sample stage 1 of this embodiment on the VeeMAX III.

[0045] First, measurements were carried out to confirm ligand adsorption. DMSO (100 μL) was dropped into the sample introduction hole 31, and background measurement was carried out. Next, the DMSO was sucked up, and the ligand solution (100 μL) was dropped into the sample introduction hole 31. Measurements were carried out immediately after dropping and one hour after dropping. The ligand spectrum confirmed that the ligand had been adsorbed.

[0046] The ligand solution on the optical element 10 was sucked up with an aspirator and washed with ion-exchanged water, after which the sample holding member 30 was removed and allowed to dry completely.

[0047] Next, the sample holding member 30 was fixed to the frame member 20, nitric acid (5 μL) was dropped into the sample introduction hole 31, the protrusion 42 was fitted into the sample introduction hole 31, and the cover member 40 was attached, and background measurement was performed. The cover member 40 was removed, and the nitric acid was absorbed.

[0048] The frame member 20, optical element 10, and sample holding member 30 were stacked in this order, and the frame member 20 and sample holding member 30 were fixed with screws 80. The frame member 20, optical element 10, and sample holding member 30 prepared in this manner, along with the cover member 40, were placed in a draft chamber, and sample X was dropped into them. 5 μL of sample X was dropped into the sample introduction hole 31, and the protrusion 42 was fitted into the sample introduction hole 31, and the cover member 40 was attached.

[0049] When the cover member 40 was attached, the sample X was sealed in a sealed space formed by the sample introduction hole 31, the sample placement surface 11, and the tip surface 42a. It was visually confirmed that the sample X was spread thinly and uniformly by being pressed against the sample placement surface 11 by the tip surface 42a. The sample stage 1 with the sample X placed in this manner was installed at a predetermined position in the infrared spectroscopic analyzer 100, and measurements were performed.

[0050] The SEIRA spectrum of the americium-DGA complex measured using the sample stage 1 of this embodiment is shown in Figure 11. This spectrum was obtained by automatically subtracting the water vapor peak from the spectrum immediately after the americium-DGA complex was added dropwise. It was confirmed that high-sensitivity measurement was possible despite the small amount of sample X used.

[0051] Furthermore, in the sample stage 1 on which the americium sample X was measured, the amount of external exposure from the sample stage 1 was 0.5 μSv. The amount of external exposure was measured using a radiation measuring device (Victoreen, 290-SI) by bringing the detector of the measuring device close to the sample stage 1. When a conventional sample stage without the cover member 40 (sample introduction hole diameter φ14 mm) was used, 300 μL of sample X was required and the amount of external exposure was 30 μSv. Therefore, the sample stage 1 was able to significantly reduce the amount of sample used and the amount of external exposure compared to the conventional sample stage.

[0052] As described above, in the sample stage 1 of this embodiment, a sealed space is formed by the sample introduction hole 31, the sample placement surface 11, and the tip surface 42a, and the tip surface 42a is configured to be able to press the sample X sealed in the sealed space toward the sample placement surface 11, thereby making it possible to reduce the amount of sample X used. Furthermore, the sample stage 1 of this embodiment is particularly useful when the sample X is a radioactive substance. Because the sample X can be sealed in a sealed space, radiation is prevented from leaking from the sample stage 1, making it possible to perform measurements safely.

[0053] [Other embodiments] The sample stage of the present disclosure can also be applied to infrared spectroscopic analysis using the transmission method. An example of application of the sample stage 1' to an infrared spectroscopic analysis device 200 using the transmission method is shown in Figure 12. The sample stage 1' is installed between the IR light source 260 and the detector 262 of the infrared spectroscopic analysis device 200. The sample stage 1' is composed of a receiving member 210, a sample holding member 230, and a cover member 240, which are stacked side by side in this order.

[0054] The receiving member 210, the sample holding member 230, and the cover member 240 are formed from an infrared-transmitting material so that the infrared light emitted from the IR light source 260 can pass through and be introduced into the detector 262. The configurations of the sample holding member 230 and the cover member 240 are the same as those in the above embodiment, but the receiving member 210 is, for example, a plate-shaped infrared-transmitting material.

[0055] A sealed space is formed by the sample introduction hole 231 formed in the sample holding member 230, the sample placement surface 211 of the receiving member 210, and the tip surface 242a of the cover member 240. The tip surface 242a can press the sample X sealed in the sealed space toward the sample placement surface 211.

[0056] The sample stage 1' of this embodiment can also obtain the same effects as those of the above embodiment. [Explanation of symbols]

[0057] 1 Sample stage 10 Receiving member (optical element) 11 Sample placement surface 20 Frame members 30 Sample holding member 31 Sample introduction hole 40 Lid member 41 Base 42 Protrusion 42a Tip surface 50 sealing material 60 IR light source 61a~d Mirror 62 detectors 70 Metal Film 100 Infrared spectrometer 200 Infrared spectrometer 210 Receiving member 211 Sample placement surface 230 Sample holding member 231 Sample introduction hole 240 Lid member 242a Tip surface X sample

Claims

1. A sample stage used in infrared spectroscopic analysis of a liquid sample containing a radioactive substance, comprising: a receiving member having a sample placement surface on which a sample can be placed; a sample holding member having a sample introduction hole penetrating in a direction intersecting the plane direction of the sample placement surface; a cover member having a protruding portion that protrudes toward the sample placement surface and can be fitted into the sample introduction hole, the sample holding member has a groove on the outer periphery of the sample introduction hole on a surface facing the receiving member, and a seal member is installed in the groove; the receiving member, the sample holding member, and the cover member are stacked in this order; A sample stage for infrared spectroscopic analysis, characterized in that an enclosed space is formed by the sample introduction hole, the sample placement surface, and the tip surface of the protrusion, and the tip surface is configured to be able to press the sample sealed in the enclosed space toward the sample placement surface.

2. 2. The sample stage for infrared spectroscopic analysis according to claim 1, wherein the sample introduction hole is circular and the protrusion is cylindrical.

3. A sample stage used in total reflection absorption spectroscopy, a frame member supporting the receiving member; 3. The sample stage for infrared spectroscopic analysis according to claim 1, wherein the receiving member is an optical element for total reflection, the sample placement surface is a total reflection surface, and the receiving member is installed on top of the frame member so that the sample placement surface is the upper surface.

4. 4. The sample stage for infrared spectroscopic analysis according to claim 1, wherein a metal film is vapor-deposited on the sample placement surface.

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