A chamber for surface-enhanced Raman scattering testing of liquid samples

Abstract

The present invention relates to the field of spectroscopy, and particularly to a chamber for surface-enhanced Raman scattering testing of liquid samples, which includes a chamber, a first pipeline, a second pipeline, a magnetothermal material part, and a noble metal part. The first pipeline and the second pipeline are fixed on both sides of the chamber, and the first pipeline and the second pipeline are connected to the chamber. The magnetothermal material part is fixed on the bottom surface inside the chamber, and the noble metal part is fixed on the top of the magnetothermal material part. The top surface of the chamber is made of a transparent material. Due to the thermophoretic phenomenon, the present invention adjusts the distance between noble metal particles, thereby adjusting the surface plasmon resonance wavelength between noble metal particles, making it easier for the surface plasmon resonance wavelength to match the incident excitation light and improving the enhancement factor of Raman signals. The present invention can achieve the above-mentioned regulation by applying an external alternating magnetic field, with convenient regulation and low regulation cost, and has good application prospects in the field of surface-enhanced Raman scattering applications.

Description

Technical Field

[0001] The present invention relates to the field of spectroscopy technology, and particularly relates to a chamber for surface-enhanced Raman scattering testing of liquid samples. Background Art

[0002] In 1974, scientists discovered that pyridine molecules adsorbed on a rough silver electrode could produce a strong Raman scattering. In 1977, it was determined that the Raman signal of pyridine molecules adsorbed on the surface of a rough silver electrode was 10 6 times stronger than that of pyridine molecules in solution. This phenomenon is called surface-enhanced Raman scattering. Surface-enhanced Raman scattering not only has extremely high detection sensitivity but also has extremely high selectivity. Therefore, surface-enhanced Raman scattering provides a new means for molecular detection and has become a research hotspot in recent years.

[0003] The focus of scientific research is to prepare various surface-enhanced Raman scattering substrates or noble metal particle structures to achieve a higher enhancement factor. For a surface-enhanced Raman scattering substrate prepared on a thin film, such as a noble metal particle array, under the irradiation of an excitation light, a strong electric field distribution is generated on the surface of the noble metal particles, and these strong electric fields enhance the Raman signals of the molecules located near the noble metal particles. For the noble metal particle structure in solution, first, the surfactant of the noble metal particle structure is modified to connect the molecules to be detected; under the irradiation of the excitation light, a strong electric field distribution is generated near the noble metal particle structure, and these strong electric fields enhance the Raman signals of the molecules located near the noble metal particle structure.

[0004] Whether it is for the surface-enhanced Raman scattering substrate on a thin film or the noble metal particle structure in solution, once it is prepared, the structure between the noble metal particles in the surface-enhanced Raman scattering substrate cannot change, and the resonance wavelength of the surface-enhanced Raman scattering substrate cannot be adjusted, making it difficult to match or resonate with the excitation light and difficult to achieve the strongest Raman signal enhancement factor; once it is prepared, since the concentration of the noble metal particles is fixed, the distance between the noble metal particles in the solution is also difficult to change, the distance between the noble metal particles cannot be adjusted, the resonance wavelength of the noble metal particles cannot be adjusted, and it is difficult to achieve the strongest Raman signal enhancement factor. Summary of the Invention

[0005] To solve the above problems, the present invention provides a chamber for surface-enhanced Raman scattering testing of liquid samples, comprising a chamber, a first pipeline, a second pipeline, a magnetothermal material part, and a noble metal part. The first pipeline and the second pipeline are fixed on both sides of the chamber, and the first pipeline and the second pipeline communicate with the chamber. During application, in the solution, surfactants are used to modify noble metal particles to link the molecules to be tested. Such a solution is input into the chamber through the first pipeline, and the tested solution is output from the chamber through the second pipeline. The magnetothermal material part is fixed on the bottom surface inside the chamber, the noble metal part is fixed on the top of the magnetothermal material part, and the top surface of the chamber is made of a transparent material. During application, the magnetothermal material part generates heat, causing the noble metal part to heat up, creating a temperature difference between the noble metal part and other parts of the solution. The noble metal particles in the solution undergo thermophoresis, move towards the noble metal part, and accumulate on the surface of the noble metal part, adjusting the distance between the noble metal particles, thereby adjusting the surface plasmon resonance wavelength between the noble metal particles, making it easier for the surface plasmon resonance wavelength to match the incident excitation light and improving the enhancement factor of the Raman signal. On the other hand, thermophoresis also increases the density of noble metal particles on the surface of the noble metal part, improving the enhancement factor of the Raman signal from another aspect.

[0006] Furthermore, the material of the magnetothermal material part is iron oxide. During application, an alternating magnetic field is applied to the magnetothermal material part, and the magnetothermal material part converts the electromagnetic wave energy into heat, thereby increasing the temperature of the noble metal part.

[0007] Furthermore, the magnetothermal material part includes a heat-insulating material part and a heat-generating material part. The heat-insulating material part is fixed on the bottom surface inside the chamber, and the heat-generating material part is fixed on the top of the heat-insulating material part. That is to say, the magnetothermal material part consists of two parts: the heat generated by the heat-generating material part is not easily transferred to the bottom of the chamber, so that the temperature of the noble metal part is higher, the thermophoresis effect is more obvious, the distance between noble metal particles can be adjusted with high sensitivity, and it is easier to adjust the surface plasmon resonance wavelength between noble metal particles.

[0008] Furthermore, the heat-generating material part is iron oxide particles. The diameter of the iron oxide particles is greater than 10 nanometers and less than 1 micrometer. Preferably, the diameter of the iron oxide particles is greater than 10 nanometers and less than 100 nanometers. Under the action of an alternating magnetic field, the iron oxide particles generate a magnetothermal effect and generate heat, thereby changing the temperature of the noble metal part.

[0009] Furthermore, the noble metal part is a thin film deposited on the iron oxide particles. The thickness of the thin film is less than 1 micrometer. Preferably, the thickness of the thin film is less than 100 nanometers. In this way, the surface of the noble metal part is rough and has the morphology of iron oxide particles. This is conducive to the aggregation of noble metal particles on the surface of the noble metal layer, coupling with the noble metal layer to generate a strong electric field, thereby enhancing the Raman signal of the molecules.

[0010] Furthermore, the material of the noble metal part is gold or silver, so as to facilitate the coupling between the noble metal part and the noble metal particles, generate a stronger local electric field, and enhance the Raman signal of the molecules.

[0011] Furthermore, the thickness of the noble metal part is less than 1 micron, so that the heat generated by the magnetothermal material part can more effectively change the temperature of the noble metal part, thereby generating a stronger thermophoresis phenomenon in the solution, and more effectively changing the distance between the noble metal particles and the wavelength of the surface plasmon resonance.

[0012] Furthermore, the magnetothermal material part and the noble metal part are cylindrical to adapt to the shape of the light spot and generate a stronger Raman signal from the molecules to be measured.

[0013] Advantages of the present invention: The present invention provides a chamber for surface-enhanced Raman scattering testing of liquid samples. By generating heat through the magnetothermal material part, the temperature of the noble metal part is changed, a thermophoresis phenomenon is generated in the solution, the distance between the noble metal particles in the solution is changed, the surface plasmon resonance wavelength between the noble metal particles and the density of the noble metal particles are changed, thereby improving the Raman signal of the molecules. In the present invention, an external alternating magnetic field can be used to regulate the surface plasmon resonance of the noble metal particles and the density of the noble metal particles, without the need to add noble metal particles again to increase the density of the noble metal particles. The regulation is convenient and the cost of regulation is low, and it has good application prospects in the field of surface-enhanced Raman scattering applications.

[0014] The following will further elaborate on the present invention in conjunction with the accompanying drawings. Description of the Drawings

[0015] Figure 1 is a schematic diagram of a chamber for surface-enhanced Raman scattering testing of liquid samples.

[0016] Figure 2 is a schematic diagram of the noble metal part composed of a disk array.

[0017] Figure 3 is a schematic diagram of a magnetothermal material part and a noble metal part.

[0018] In the figure: 1. Chamber; 2. First pipeline; 3. Second pipeline; 4. Magnetothermal material part; 5. Noble metal part; 41. Adiabatic material part; 42. Heating material part; 51. Disk. Detailed Embodiments

[0019] To make the objectives, technical solutions and advantages of the present application clearer, the following examples are given with reference to the accompanying drawings to further elaborate on the present application in detail.

[0020] Example 1

[0021] The present invention provides a chamber for surface-enhanced Raman scattering testing of liquid samples, such as Figure 1As shown, it includes a chamber 1, a first pipe 2, a second pipe 3, a magnetocaloric material part 4, and a noble metal part 5. The first pipe 2 and the second pipe 3 are fixed on both sides of the chamber 1, and the first pipe 2 and the second pipe 3 communicate with the chamber 1. The chamber 1 can be cubic or cuboid. The cross-sections of the first pipe 2 and the second pipe 3 can be circular or square. In application, in a solution, a surfactant is used to modify noble metal particles to link the molecules to be tested, forming a noble metal particle solution including the linked molecules to be tested. Such a solution is input into the chamber 1 through the first pipe 2, and the tested solution is output from the chamber 1 through the second pipe 3. The material of the noble metal particles is gold, silver, or platinum, and its material is selected according to specific molecules, which is not limited here. The magnetocaloric material part 4 is fixed on the bottom surface inside the chamber 1, and the noble metal part 5 is fixed on the top of the magnetocaloric material part 4. The magnetocaloric material part 4 and the noble metal part 5 are cylindrical to adapt to the shape of the light spot, so that the molecules to be tested generate stronger Raman signals. On the other hand, the surface area of the noble metal part 5 is larger than the area of the light spot of the incident excitation light. The top surface of the chamber 1 is made of a transparent material, which can be silica, to facilitate the incident excitation light to pass through the top surface of the chamber 1 and irradiate the noble metal particles, and the Raman signal generated by the molecules to be tested passes through the top surface of the chamber 1. For a micro-Raman spectroscopy system, the present invention is placed under the objective lens of the micro-Raman spectroscopy system. The excitation light emitted from the objective lens passes through silica, irradiates the noble metal particles and the molecules to be tested. The Raman signal generated by the molecules to be tested passes through silica and is collected by the objective lens, and then enters the spectroscopy system. Except that the top surface of the chamber 1 uses a transparent material, there is no limitation on the materials of the side surface and the bottom surface of the chamber 1. It can use silica material or corrosion-resistant organic material. The material of the magnetocaloric material part 4 is a lump of iron tetroxide. In application, an alternating magnetic field is applied to the magnetocaloric material part 4, and the magnetocaloric material part 4 converts the electromagnetic wave energy into heat, thereby increasing the temperature of the noble metal part 4. Under the action of the alternating magnetic field, the magnetocaloric material part 4 generates heat, causing the noble metal part 5 to heat up, resulting in a temperature difference between the noble metal part 5 and other parts of the solution. The noble metal particles in the solution undergo thermophoresis, move towards the noble metal part 5, and aggregate on the surface of the noble metal part 5, adjusting the distance between the noble metal particles, thereby adjusting the surface plasmon resonance wavelength between the noble metal particles, making it easier for the surface plasmon resonance wavelength to match the incident excitation light and increasing the enhancement factor of the Raman signal. On the other hand, the thermophoresis phenomenon also increases the density of noble metal particles on the surface of the noble metal part 5, improving the enhancement factor of the Raman signal from another aspect. In the present invention, the surface plasmon resonance of noble metal particles and the density of noble metal particles can be regulated by using an external alternating magnetic field, without the need to add noble metal particles again to increase the density of noble metal particles. The regulation is convenient and the cost of regulation is low, and it has good application prospects in the field of surface-enhanced Raman scattering applications.

[0022] Example 2

[0023] On the basis of Example 1, the thickness of the noble metal part 5 is less than 1 micron. Further, the thickness of the noble metal part 5 is less than 100 nanometers, so that the heat generated by the magnetothermal material part 4 can more effectively change the temperature of the noble metal part 5, thereby forming a higher temperature in the solution, generating a stronger thermophoretic phenomenon in the solution, causing more noble metal particles to move towards the noble metal part 5, and more effectively changing the distance between noble metal particles and the wavelength of surface plasmon resonance. Additionally, the cross-sectional area of the noble metal part 5 is smaller than that of the magnetothermal material part 4, which is conducive to more effectively changing the temperature of the noble metal part 5. This can more flexibly change the wavelength of surface plasmon resonance between noble metal particles, facilitating the matching of the surface plasmon resonance wavelength with the wavelength of the incident excitation light, exciting a stronger electric field on the surface of noble metal particles, and increasing the enhancement factor of the Raman signal. The material of the noble metal part 5 is gold or silver. When noble metal particles move towards the noble metal part 5 and aggregate on its surface, it is conducive to the coupling between the noble metal part 5 and the noble metal particles, concentrating the electric field not only between noble metal particles but also between noble metal particles and the noble metal part 5, generating a stronger local electric field. These local electric fields enhance the Raman signal of molecules and increase the enhancement factor of the molecular Raman signal. On the other hand, since the noble metal part is in the form of a film, the noble metal part 5 also reflects the Raman signal generated by molecules, further enhancing the Raman signal detected by the objective lens.

[0024] During preparation, first, the magnetite material is cut to form a cylindrical magnetothermal material part 4. Then, physical vapor deposition methods, such as electron beam evaporation coating and magnetron sputtering evaporation coating methods, are used to deposit the noble metal part 5 on the top surface of the magnetothermal material part 4. The preparation method is simple. The thickness of the noble metal part 5 can be controlled by a film thickness detection system. For example, the thickness of the noble metal part 5 can be detected by a quartz crystal oscillator system, achieving nanometer-level precision.

[0025] Example 3

[0026] On the basis of Example 2, as Figure 2As shown, the noble metal part 5 is an array of disks 51 arranged periodically. That is to say, the noble metal part 5 is composed of disks 51 arranged periodically. The arrangement period of the disks 51 is a square period. The diameter of the disks 51 is greater than 40 nm and less than 200 nm. The height of the disks 51 is greater than 20 nm and less than 400 nm. The distance between the disks 51 edge to edge is less than 1 μm. Under the action of an externally applied alternating magnetic field, the magnetite material generates heat, and this heat is transferred to the disk 51 array, raising the temperature of the disks 51, that is, forming individual "hot spots". Under the action of the thermophoretic effect, noble metal particles gather near each disk 51. That is to say, noble metal particles gather not only on the top of the disks 51, but also on the sides of the disks 51. The noble metal particles gathered on the sides of the disks 51 have a stronger coupling with the disks 51 because this coupling is in the direction of the polarization of light. This strong coupling causes a stronger local electric field to be generated on the surface of the noble metal particles, especially between the noble metal particles and the disks 51, and these local electric fields are beneficial to enhancing the Raman signal of molecules more. In addition, due to the disks 51 having a certain thickness, more noble metal particles can also gather on the sides of the disks 51, thereby enhancing the Raman signal of molecules.

[0027] During preparation, spin coating can be first performed on the magnetothermal material part 4, and then the disk 51 array can be prepared by using ordinary electron beam lithography and vacuum coating methods. Similarly, the thickness of the disks 51 can be controlled by a film thickness monitoring system.

[0028] In this embodiment, the thickness of the disks 51 should not exceed 1 μm to prevent the disks 51 themselves from strongly absorbing the molecular Raman signal, resulting in less Raman signal exiting from the top surface of the chamber.

[0029] Embodiment 4

[0030] Based on Embodiment 1, as Figure 3 shown, the magnetothermal material part 4 includes a heat insulation material part 41 and a heat generating material part 42. The heat insulation material part 41 is fixed on the bottom surface inside the chamber 1, and the heat generating material part 42 is fixed on the top of the heat insulation material part 41. Preferably, the cross-sectional area of the heat generating material part 42 is smaller than the cross-sectional area of the heat insulation material part 41 to obtain a stable support effect. The heat transfer effect or heat conduction effect of the heat insulation material part 41 is poor. The material of the heat insulation material part 41 is a heat insulation material, and the heat insulation material can block the heat flow transfer and is also called a thermal insulation material. In this embodiment, the material of the heat insulation material part 41 can be fiberglass, silicate, aerogel felt, vacuum panel, etc. That is to say, the magnetothermal material part 4 includes two parts: the heat generated by the heat generating material part 42 is not easily transferred to the bottom of the chamber 1, so that the temperature of the noble metal part 5 is higher, the thermophoretic effect is more obvious, the distance between noble metal particles can be adjusted with high sensitivity, and the surface plasmon resonance wavelength between noble metal particles is more easily adjusted.

[0031] Example 5

[0032] On the basis of Example 4, the heat - generating material part 42 is composed of magnetite particles. The diameter of the magnetite particles is greater than 10 nanometers and less than 1 micrometer. Preferably, the diameter of the magnetite particles is greater than 10 nanometers and less than 100 nanometers. Under the action of an alternating magnetic field, the magnetite particles generate a magnetothermal effect and produce heat, thereby changing the temperature of the noble - metal part 5. The noble - metal part 5 is a thin film deposited on the magnetite particles. The thickness of the thin film is less than 1 micrometer. Preferably, the thickness of the thin film is less than 100 nanometers. In this way, the surface of the noble - metal part 5 is rough and has the morphology of magnetite particles. This is conducive to the aggregation of noble - metal particles on the surface of the noble - metal part 5 and the generation of a strong electric field by coupling with the noble - metal part 5, thereby enhancing the Raman signal of molecules.

[0033] During preparation, first, the magnetite particles are laid on the heat - insulating material part 41, and then in a vacuum chamber, a noble - metal film is evaporated on the magnetite particles. Due to the small thickness of the noble - metal film, the noble - metal film has the shape of magnetite particles, that is, a rough surface, which can form a concave shape on the surface of the noble - metal film. More noble - metal particles can be aggregated at the concave part, and a stronger local electric field can also be formed at the concave part, thereby enhancing the Raman signal of molecules. Further, the magnetite particles are arranged in multiple layers, that is, the number of magnetite particles is more than two layers. In this way, due to the interlacing between layers, after evaporating the noble - metal film, more holes, that is, a porous shape, are formed on the surface. These holes are conducive to the aggregation of noble - metal particles and the formation of a local electric field, thereby enhancing the Raman signal of molecules.

[0034] In summary, the present invention uses the magnetic - heat material part 4 to generate heat, changes the temperature of the noble - metal part 5, generates a thermophoretic phenomenon in the solution, enables noble - metal particles to aggregate around the noble - metal part 5, changes the surface plasmon resonance wavelength of the entire system, and also changes the density of noble - metal particles, thereby increasing the enhancement factor of the Raman signal. The present invention can regulate the heat generated by the magnetic - heat material part 4 by adjusting the frequency or intensity of the applied alternating magnetic field, and further regulate the thermophoretic phenomenon. The regulation is simple and the regulation cost is low. It has good application potential not only in the field of surface - enhanced Raman scattering detection, but also in spectroscopic technologies such as infrared absorption and ultraviolet fluorescence.

[0035] The above - mentioned are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A chamber for surface-enhanced Raman scattering testing of liquid samples, characterized in that, It includes a chamber, a first pipe, a second pipe, a noble metal part, a heat insulating material part, and a heating material part; the first pipe and the second pipe are fixed on both sides of the chamber, the first pipe and the second pipe communicate with the chamber, the heat insulating material part is fixed on the bottom surface inside the chamber, the heating material part is fixed on the top of the heat insulating material part, the noble metal part is fixed on the top of the heating material part, and the top surface of the chamber is made of a transparent material; wherein, the heating material part is composed of magnetite particles, the noble metal part is a thin film deposited on the magnetite particles, and the thickness of the thin film is less than 1 micron.

2. The chamber for surface-enhanced Raman scattering testing of liquid samples according to claim 1, wherein: The diameter of the magnetite particles is greater than 10 nanometers and less than 1 micron.

3. The chamber for surface-enhanced Raman scattering testing of liquid samples according to claim 1, wherein: The material of the noble metal part is gold.

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