An infrared spectroscopy detection method and its ultrasonic standing wave sample cell for detection

Abstract

This invention relates to the field of spectral detection technology, and more particularly to an infrared spectral detection method and its ultrasonic standing wave sample cell. The method includes a frame, an upper rotating cover, and a speaker bracket. The upper rotating cover is mounted on top of the frame, and the speaker bracket is mounted on the bottom of the upper rotating cover. An ultrasonic speaker is installed inside the speaker bracket. The frame includes a supporting base plate and a top plate, which are connected to each other by connecting columns. An arc-shaped through-slot is formed on the top plate. This invention introduces an ultrasonic standing wave field into infrared spectral detection and applies it to the infrared spectral detection sample cell. The ultrasonic standing wave enhances the sensitivity and resolution of the spectral signal. The design does not require large-scale modifications to existing infrared spectrometers, and the method is simple to operate and maintain. It overcomes the shortcomings of existing technologies that neglect the influence of sample molecular vibration states when adjusting the sample cell structure, thus improving the spectral response efficiency and signal quality of samples in infrared spectral analysis.

Description

Technical Field

[0001] This invention relates to the field of spectral detection technology, and in particular to an infrared spectral detection method and an ultrasonic standing wave sample cell for the detection. Background Technology

[0002] Currently, infrared spectroscopy is widely used in the composition analysis, structural identification, and quality control of solid samples. It offers advantages such as being non-destructive, rapid, and sensitive, and is particularly prevalent in materials science, environmental monitoring, and food testing. The infrared spectroscopy detection process relies heavily on the design of the sample cell, whose performance has a crucial impact on the measurement results.

[0003] For example, patent CN108226080A proposes a multi-channel infrared sample chamber device. By setting up a multi-channel sample chamber with an infrared lens and detachable connectors, it enables the simultaneous placement of multiple samples, avoiding the introduction of moisture due to frequent opening and closing, thereby improving test stability. Patent CN201810043788.2 discloses a high-pressure in-situ infrared sample cell, which can measure the infrared spectrum of CO2-organic liquid systems under 10MPa high pressure, intuitively demonstrating the effect of pressure on molecular interactions, and is simple and reliable to operate. Patent CN116087103A proposes a compact sample stage and sample analysis system for infrared and Raman spectroscopy analysis, which uses a plug-in structure to facilitate the replacement and cleaning of the sample cell.

[0004] The aforementioned patents primarily achieve spectral detection by altering and designing the appearance and structure of the sample cell. However, they fail to incorporate ultrasonic standing wave fields into spectral analysis and neglect the limitations of the sample's molecular vibrational state. Traditional infrared spectroscopy relies on absorption signals generated by the natural vibrations of molecules themselves (such as bond stretching and bending). However, in high-pressure or complex systems, molecular vibrations may be suppressed or interfered with by environmental pressure and intermolecular interactions (such as hydrogen bonds and van der Waals forces), leading to a significant reduction in signal intensity. Existing sample cell designs only provide a passive detection environment and do not actively enhance molecular vibrations or modulate vibrational modes through external means, resulting in signals from low-concentration components or weak interactions being masked by noise.

[0005] Therefore, an infrared spectroscopy detection method and an ultrasonic standing wave sample cell for detection are needed to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide an infrared spectroscopy detection method and an ultrasonic standing wave sample cell for detection. By introducing an ultrasonic standing wave field, the response efficiency and signal quality of the sample in infrared spectroscopy detection are improved, thereby overcoming the shortcomings of existing technologies that adjust the sample cell structure while ignoring the influence of the sample molecular vibration state. This sample cell utilizes the ultrasonic standing wave effect to significantly enhance the sensitivity and resolution of the spectral signal, making it particularly suitable for the detection and analysis of complex multiphase systems.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0008] A detection method for an ultrasonic standing wave sample cell used in infrared spectroscopy includes the following steps:

[0009] Step 1: Select the ultrasonic frequency ω according to the properties of the sample to be tested, and calculate the sound wavelength λ using the formula λ=v / ω, where v is the speed of sound; adjust the distance between the two ultrasonic speakers to nλ / 2, and set the initial phase difference between the two ultrasonic speakers to 180°, where n is an integer ≥1;

[0010] Step 2: With the ultrasonic speaker off, place the sample to be tested. The sample may include liquid, solid, or gas samples.

[0011] For liquid samples, the ultrasonic standing wave sample cell is covered with an acrylic transparent sealing cover to make the ultrasonic standing wave sample cell a closed space. A heating plate is placed in the sealing cover and heated to 70°C. A through hole is made in the sealing cover. The liquid sample to be tested is dropped onto the heating plate with a needle to make the liquid sample evaporate. After the liquid sample evaporates, it is scanned with an infrared spectrometer to obtain infrared spectral data.

[0012] For solid samples, the powder sample is pressed into a potassium bromide sheet and fixed in the detection area of ​​the speaker bracket. The ultrasonic speaker is turned on, and after the acoustic standing wave field has been running stably for 20 seconds, an infrared spectrometer is used to scan and obtain infrared spectral data.

[0013] For gas samples, the ultrasonic standing wave sample cell is covered with an acrylic transparent sealing cover to keep the ultrasonic standing wave sample cell in a closed space. A heating plate is placed in the sealing cover and heated to 70°C. A through hole is made on the sealing cover, and the gas sample to be tested is injected into the through hole to evaporate the liquid sample. Then, the ultrasonic speaker is turned on to form an acoustic standing wave field at a preset frequency ω and phase difference. After the acoustic standing wave field has been running stably for 20 seconds to achieve the compression and enrichment of the gas sample, it is scanned with an infrared spectrometer to obtain infrared spectral data.

[0014] Furthermore, the ultrasonic frequency ω in step 1 ranges from 30 to 50 kHz, corresponding to an antinode or node width of 2.5 mm to 4.3 mm.

[0015] Furthermore, in step 1, the initial phase difference adjustment of the two ultrasonic speakers is achieved through a PWM power supply. By switching the phase angle of the two ultrasonic speakers, the position of the antinode is controlled to be located in the center or edge region of the ultrasonic speaker.

[0016] The present invention also provides an ultrasonic standing wave sample cell for infrared spectroscopy detection, including a frame, an upper rotating cover and a speaker bracket. The upper rotating cover is installed on the top of the frame, the speaker bracket is installed on the bottom of the upper rotating cover, and an ultrasonic speaker is installed inside the speaker bracket.

[0017] The frame includes a supporting base plate and a top plate, which are connected to each other by connecting columns. An arc-shaped through groove is provided on the top plate.

[0018] The upper rotating cover is installed inside the limiting component, and a rotating handle is installed on the upper rotating cover. Symmetrically arranged square through holes are opened on the upper rotating cover.

[0019] The speaker bracket has a speaker mounting hole, and the ultrasonic speaker is installed in the speaker mounting hole. A square tenon is fixedly connected to the top of the speaker bracket, and the speaker bracket is connected to the square through hole on the upper rotating cover through the square tenon.

[0020] Furthermore, the upper end of the top plate is fixedly connected with symmetrically arranged limiting members, and a limiting slot is opened in the limiting member.

[0021] Furthermore, the upper rotating cover has symmetrically arranged flanges, which engage with each other through the flanges and the limiting slots.

[0022] Furthermore, a wiring hole A is provided in the middle of the top plate, a wiring hole B is provided on the rotating handle, and a wiring hole C is provided on the square tenon. Wiring holes A, B, and C are all used for wiring the ultrasonic speaker circuit.

[0023] Furthermore, the support base plate has threaded holes with a diameter of 6mm for the installation and positioning of the frame and the infrared spectrometer.

[0024] The advantages of this invention are: 1. This invention introduces an ultrasonic standing wave field into infrared spectroscopy detection, applies the ultrasonic standing wave field to the sample cell for infrared spectroscopy detection, and enhances the sensitivity and resolution of the spectral signal through the ultrasonic standing wave effect, thereby improving the Fourier transform infrared spectroscopy detection results of ethanol and indium oxide ( Figure 7 and Figure 8From the perspective of ultrasound standing wave effect, the spectral signal is significantly enhanced, resulting in more accurate and clearer detection results. Furthermore, this sample cell can adapt to samples of various morphologies, and the ultrasonic standing wave field can enhance the detection effect on samples in complex systems, demonstrating broad applicability. Moreover, its design does not require large-scale modifications to existing infrared spectrometers, making it simple to operate and maintain. It overcomes the shortcomings of existing technologies that neglect the influence of sample molecular vibrational states when adjusting the sample cell structure, thus improving the spectral response efficiency and signal quality of samples in infrared spectral analysis.

[0025] 2. This invention features an adjustable structure, allowing the angle and spacing of the ultrasonic loudspeakers to be adjusted by rotating the upper rotating cover. The ultrasonic loudspeaker spacing in the sample cell can be adjusted between 14.5 mm and 10 mm, and the ultrasonic standing wave field angle can vary between 0 and 90 degrees. This adapts to different experimental conditions and sample characteristics, improving the versatility of the sample cell. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the airtightness test principle of the present invention.

[0028] Figure 2 for Figure 1 A partially enlarged structural diagram.

[0029] Figure 3 This is a schematic diagram of the structure of an ultrasonic standing wave sample cell for infrared spectroscopy detection according to the present invention.

[0030] Figure 4 This is an enlarged structural schematic diagram of the upper rotating cover in this invention.

[0031] Figure 5 This is an enlarged structural diagram of the frame in this invention.

[0032] Figure 6 This is an enlarged structural schematic diagram of the speaker bracket in this invention.

[0033] Figure 7 This is the Fourier transform infrared spectrum of ethanol in a sealed sample cell.

[0034] Figure 8 The Fourier transform infrared spectrum of indium oxide with and without ultrasonic treatment.

[0035] Figure 9 This is a schematic diagram of two opposing loudspeakers, with the distance between them being three and a half wavelengths.

[0036] Figure 10 This is a schematic diagram of two opposing loudspeakers with a distance of 2.5 wavelengths.

[0037] Figure 11 This is a schematic diagram of a schlieren imaging system.

[0038] Figure 12 This is a schematic diagram illustrating the sound pressure distribution and energy density of the standing wave field under different spacing conditions obtained through simulation.

[0039] in:

[0040] 1. Frame; 101. Support base plate; 1011. Threaded hole;

[0041] 102. Connecting column; 103. Top plate; 1031. Arc-shaped through groove;

[0042] 1032, Limiting component; 10321, Limiting slot; 1033, Wiring hole A;

[0043] 2. Ultrasonic speaker; 3. Detector; 4. Infrared light source;

[0044] 5. Upper rotating cover; 501. Cover plate; 5011. Square through hole;

[0045] 5012, Flange; 502, Rotary Handle; 5021, Cable Tray Hole B;

[0046] 6. Speaker bracket; 601. Bracket body; 6011. Speaker mounting holes;

[0047] 602, Square tenon; 6021, Wiring hole C; 7, Capillary tube;

[0048] 8. Potassium bromide tablets. Detailed Implementation

[0049] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] Example 1: Figure 1 This is a schematic diagram of the airtightness test principle of the present invention; Figure 2 for Figure 1 A partially enlarged structural diagram; Figure 3 This is a schematic diagram of the structure of an ultrasonic standing wave sample cell for infrared spectroscopy detection according to the present invention; Figure 4 This is an enlarged structural schematic diagram of the upper rotating cover 5 in this invention; Figure 5 This is an enlarged structural schematic diagram of the frame 1 in this invention; Figure 6 This is an enlarged structural schematic diagram of the speaker bracket 6 in this invention; as shown... Figures 1 to 6 An ultrasonic standing wave sample cell for infrared spectroscopy detection is shown. The ultrasonic standing wave sample cell includes a frame 1, an upper rotating cover 5, and a speaker bracket 6. The upper rotating cover 5 is installed on the top of the frame 1, and the speaker bracket 6 is installed on the bottom of the upper rotating cover 5. An ultrasonic speaker 2 is installed inside the speaker bracket 6. The ultrasonic speaker bracket 6 of this invention is suitable for installing an ultrasonic speaker 2 with a diameter of 10 mm. A speaker mounting hole 6011 is provided inside the speaker bracket 6, and the ultrasonic speaker 2 is installed inside the speaker mounting hole 6011. The speaker bracket 6 includes a bracket body 601, and a square tenon 602 is fixedly connected to the top of the bracket body 601. The speaker bracket 6 is connected to a square through hole 5011 on the upper rotating cover 5 via the square tenon 602. The square tenon 602 at the top of the speaker bracket 6 can be connected to the square through hole 5011 on the upper rotating cover 5. A wiring hole C6021 with a diameter of 4 mm is provided on the square tenon 602 for wiring the ultrasonic speaker 2.

[0052] The frame 1 of this invention includes a supporting base plate 101 and a top plate 103, which are connected to each other by a connecting column 102. A wiring hole A1033 is provided in the middle of the top plate 103 for wiring of the ultrasonic speaker 2. The frame 1 of this invention has dimensions of 52mm × 52mm × 108.8mm. A threaded hole 1011 with a diameter of 6mm is provided on the supporting base plate 101 for the installation and positioning of the frame 1 and the infrared spectrometer (not shown in the figure). Furthermore, a groove can be opened on the bottom surface of the frame 1 and a ceramic heating element can be placed in the groove to heat the atmospheric sample in an airtight environment. The top plate 103 has an arc-shaped through groove 1031 with a width of 10mm and an angle of 120 degrees, which is used to enable the ultrasonic speaker bracket 6 to rotate and move after installation. In addition, a symmetrically arranged limiting member 1032 is fixedly connected to the upper end of the top plate 103. A limiting slot 10321 is provided in the limiting member 1032 to limit the upper rotating cover 5 and fix the position of the upper rotating cover 5 during the rotation and movement process.

[0053] In this invention, the upper rotating cover 5 is installed within the limiting member 1032. A rotating handle 502 is mounted on the upper rotating cover 5. A square through hole 5011 with a side length of 7 mm is located symmetrically on the upper rotating cover 5 for assembling the ultrasonic speaker bracket 6. Specifically, the upper rotating cover 5 is a circular cover plate 501 with a diameter of 47.9 mm. The upper rotating cover 5 has symmetrically arranged flanges 5012, which engage with the limiting slot 10321. Grooves with a width of 3.7 mm and an angle of 60 degrees are respectively opened on both sides of the upper rotating cover 5, located between the two flanges 5012, serving to adapt to and install the overall frame 1. The rotating handle 502 at the upper end of the upper rotating cover 5 (e.g., ...) Figure 4 As shown, each location (including the cylindrical support structure) has a 6mm diameter wiring hole B5021 for wiring of the ultrasonic speaker 2.

[0054] The sample pool after overall installation is as follows Figure 3 As shown, the distance between the two ultrasonic speaker brackets 6 is 14.5 mm, and the distance between the two ultrasonic speakers 2 can be adjusted according to the experimental conditions. The adjustment range is from 14.5 mm to 10 mm. By rotating the handle 502, the angle position of the ultrasonic standing wave field acting on the sample material surface can be changed between 0 and 90 degrees through the arc-shaped through slot 1031 opened on the top plate 103.

[0055] Figure 7 This is the Fourier transform infrared spectrum of ethanol in a sealed sample cell. Figure 8The Fourier transform infrared spectrum of indium oxide with and without ultrasonic treatment is shown. During the airtightness test, acrylic plates were first installed around the sample cell to achieve a seal. Circular windows with a diameter of 20 mm were opened at the two opposite panels through which infrared light passes, and barium fluoride windows were used for installation and sealing to ensure good transmission of the infrared beam (not shown in the figure, for illustrative purposes only). Figure 7 This demonstrates Fourier transform infrared spectroscopy (FTIR) detection of ethanol within a sealed sample cell. The dashed line represents the case without ultrasonic standing wave interference, while the solid line represents the case with ultrasonic standing wave interference.

[0056] The schematic diagram for sample testing is as follows: Figure 8 As shown, the experimental method is the same as the airtightness test. A capillary tube 7 is connected to the bottom of the top plate 103, and a potassium bromide sheet 8 is connected to the lower end of the capillary tube 7. The capillary tube 7 is used to fix the position of the potassium bromide sheet 8, and the potassium bromide sheet 8 is the carrier of the test sample, ensuring that the potassium bromide sheet 8 passes through the infrared light path. Figure 8 The image shows Fourier transform infrared spectroscopy (FTIR) detection of indium oxide within a sealed sample cell. The dashed line represents the case without ultrasonic standing wave interference, while the solid line represents the case with ultrasonic standing wave interference.

[0057] Regarding the installation of the ultrasonic loudspeaker, in addition to using the ultrasonic loudspeaker bracket 6 in this solution, a magnetic mounting structure can also be considered. This uses magnetic materials to fix the ultrasonic loudspeaker in the appropriate position, making it more convenient to replace the ultrasonic loudspeaker. For the sealing method of the sample cell, besides using acrylic sheets and barium fluoride windows, new sealants or sealing films can be explored to further improve the sealing performance of the sample cell while ensuring infrared light transmittance.

[0058] The present invention also provides a detection method for an ultrasonic standing wave sample cell for infrared spectroscopy detection, comprising the following steps:

[0059] Step 1: Select the ultrasonic frequency ω based on the properties of the sample to be tested. Calculate the sound wavelength λ using the formula λ=v / ω, where v is the speed of sound. To form a stable standing wave field, the distance between the two speakers must be an integer multiple of half the wavelength, i.e., distance = nλ / 2. Set the initial phase difference between the two ultrasonic speakers to 180°, where n is an integer ≥ 1. Thus, a node is the weakest point of resonance, while an antinode is the strongest. A node and an antinode are considered as one point, and their respective regions extend λ / 8 from their centers to both ends, i.e., the width of both nodes and antinodes is λ / 4. The distance between the centers of adjacent nodes and antinodes is λ / 4. The initial phase difference between the two ultrasonic speakers is adjusted using a PWM power supply. By switching the phase angle of the two ultrasonic speakers, the position of the antinode is controlled to be either in the center or edge region of the ultrasonic speaker. Figure 9A schematic diagram showing two opposing ultrasonic speakers spaced three times half a wavelength apart, as shown below. Figure 9 As shown in the diagram, the initial phase of ultrasonic speaker 1 is 0°, and the initial phase of ultrasonic speaker 2 is 180°. Therefore, the center position of the two ultrasonic speakers is the antinode. When the initial phases of the two ultrasonic speakers are adjusted, with the initial phase of ultrasonic speaker 1 being 90° and the initial phase of ultrasonic speaker 2 being -90°, the center position can be adjusted to the node.

[0060] Figure 10 A schematic diagram showing two opposing loudspeakers spaced at twice half a wavelength, as shown below. Figure 10 As shown, after adjusting the distance between the two ultrasonic speakers, when the distance between the two ultrasonic speakers is twice half a wavelength, the relative distance between the centers of the nodes and antinodes remains λ / 4, and the width of the nodes and antinodes remains λ / 4. Figure 9 The principle is the same as in the previous example. The initial phase of ultrasonic speaker 1 is 0°, and the initial phase of ultrasonic speaker 2 is 180°. The center position of the two ultrasonic speakers is the antinode. When the initial phases of the two ultrasonic speakers are adjusted, with the initial phase of ultrasonic speaker 1 being 90° and the initial phase of ultrasonic speaker 2 being -90°, the center position can be adjusted to the node.

[0061] Similarly, by ensuring that the relative distance between the two ultrasonic speakers is an integer multiple of half the wavelength, the number of nodes and antinodes can be adjusted. By ensuring that the initial phase difference between the two ultrasonic speakers is 180°, the positions of the nodes and antinodes can be adjusted.

[0062] Step 2: For liquid samples, add the liquid sample dropwise to a 70°C heating plate to evaporate it, creating a uniform gas concentration testing environment; Figure 1 The ultrasonic standing wave sample cell is covered by a transparent acrylic sealing cover to ensure the ultrasonic device is in a sealed space. An inlet and an outlet are provided on the acrylic sealing cover. The inlet uses potassium bromide material to ensure that infrared light passes through without energy loss. A heating plate is placed inside the sealing cover and its temperature is controlled at 70 degrees Celsius. A small hole is made in the sealing cover, and the liquid sample to be tested is dropped onto the heating plate using a needle, causing the liquid sample to evaporate. This allows the gas concentration in the same volume of space to be changed by altering the amount of liquid sample. With the speaker off, a certain volume of ethanol is injected, allowing the ethanol to evaporate in the sealing cover. After 50 seconds of complete evaporation, the infrared spectrum is scanned to obtain... Figure 7 The dashed line in the image. With the speaker on, the same volume of ethanol is injected, and after 50 seconds of complete evaporation, the infrared spectrum is scanned to obtain... Figure 7The solid line in the image clearly shows that the signal intensity of the solid line spectral peak has increased by nearly 100%, indicating that ethanol vapor is compressed and enriched under the action of the ultrasonic standing wave field. This is corroborated by schlieren imaging. Furthermore, new spectral peaks appear at 1550 cm⁻¹, 1700 cm⁻¹, 3700 cm⁻¹, and 3800 cm⁻¹. This is due to the enrichment effect of ultrasound, which improves the sensitivity of the instrument and detects water vapor in the air. The peaks at 1550 cm⁻¹ and 1700 cm⁻¹ are from the variable-angle vibration of H₂O, the peak at 3700 cm⁻¹ is from the antisymmetric stretching vibration of H₂O, and the peak at 3800 cm⁻¹ is from the symmetric stretching vibration of H₂O. Specifically, using CO₂ gas as a sample, under 40 kHz sound waves, with an antinode spacing of 4.3 mm and a sound pressure difference of 500 Pa, the gas concentration increases by 80%. The infrared absorption peak at 2349 cm⁻¹ increases in intensity by 3 times, and a new peak appears at 2375 cm⁻¹ (corresponding to excited-state vibration).

[0063] Figure 8 The Fourier transform infrared spectra of indium oxide with and without ultrasonic treatment are shown below. Figure 8 As shown, when the ultrasonic loudspeaker is in the off state, the infrared spectrum is plotted to obtain... Figure 8 The dotted line in the diagram. The powder sample is pressed into a potassium bromide sheet and fixed to the detection area of ​​the speaker bracket; the ultrasonic speaker is turned on, and a standing wave field is formed at a preset frequency ω and phase difference. It is run stably for 20 seconds, allowing the molecular structure of the solid sample to be modulated by the sound waves, thus obtaining... Figure 8 As shown by the solid line, the two spectral peaks at 750 cm⁻¹ and 1070 cm⁻¹ are clearly enhanced under the influence of the ultrasonic standing wave field. The peak at 750 cm⁻¹ represents O⁻ ions (negative oxygen ions), while the peak at 1070 cm⁻¹ represents O₂⁻ ions (superoxide ions). The peak values ​​of superoxide ions and negative oxygen ions gradually increase with ultrasonic treatment. Analysis of this phenomenon leads to the following conclusion: the mechanism by which ultrasonic standing waves affect the oxygen partial pressure of the system exhibits a unique regularity. Due to the weakened intermolecular interactions, the changes in energy transfer and distribution in the ultrasonic standing wave field have a more significant regulatory effect on the motion state of oxygen molecules, thus directly affecting the oxygen partial pressure of the system. In low-concentration environments, a higher oxygen partial pressure (relative to the low background concentration conditions) provides a thermodynamic advantage for the adsorption of oxygen atoms on the surface of indium oxide materials, promoting the activated adsorption of oxygen molecules. When oxygen atoms adsorb onto the surface of indium oxide, oxygen vacancies are formed within the crystal lattice. This process amplifies its impact on the material's electronic structure under low concentration conditions: due to the low carrier concentration of indium oxide itself, the consumption of electrons during the reaction directly leads to a significant decrease in the internal carrier concentration, resulting in a rapid increase in the resistance of the sensing material. As the duration of the acoustic standing wave field increases, the adsorption process exhibits a cumulative effect. More oxygen atoms overcome the adsorption energy barrier with the energy assistance of the standing wave field, causing a gradual increase in the oxygen vacancy concentration, intensified electron consumption, and a continuous rise in sensor resistance. This microscopic change is reflected in the infrared spectrum as the vibrational peaks of superoxide ions and negative oxygen ions gradually increase with increasing adsorption amount, reflecting the directional regulation of gas molecule adsorption behavior by the acoustic standing wave.

[0064] For gas samples, the ultrasonic standing wave sample cell is covered with an acrylic transparent sealing cover to keep the ultrasonic standing wave sample cell in a closed space. A heating plate is placed in the sealing cover and heated to 70°C. A through hole is made in the sealing cover, and the gas sample to be tested is injected into the through hole. Then, the ultrasonic speaker is turned on to form an acoustic standing wave field at a preset frequency ω and phase difference. After the acoustic standing wave field has been running stably for 20 seconds to achieve the compression and enrichment of the gas sample, it is scanned with an infrared spectrometer to obtain infrared spectral data. Figure 11 This is a schematic diagram of a schlieren imaging system, such as... Figure 11 The schlieren imaging system shown includes a camera, a filter, a concave mirror, and a point light source. The point light source is placed parallel to the filter at twice the focal length of the concave mirror. The camera is placed behind the filter for image reception. This system amplifies the light refraction phenomenon caused by differences in gas concentration due to temperature variations through the concave mirror. It is based on the phenomenon of light refraction in different media. When light propagates in a uniform spatial medium, it travels in a straight line. This is because the physical properties of the medium remain consistent in space without altering the light path. However, when light enters a medium with uneven density distribution, refraction occurs. Snell's law in optics can explain this phenomenon. That is: In the formula, n1 and n2 represent the refractive indices of the two media, respectively, and θ1 and θ2 are the incident angle and refraction angle of the light rays at the incident surface, respectively.

[0065] Figure 12 To illustrate the sound pressure distribution and energy density of the standing wave field under different spacing conditions using simulation, as shown below... Figure 12As shown, the leftmost image utilizes 3D AcousticSIM software for detailed simulation. The simulation obtained key parameters such as sound pressure distribution and energy density of the standing wave field under different spacing conditions. The simulation used a generation frequency of 40 kHz, with the distance between the two ultrasonic speakers being 1.5 times the wavelength. The middle and right images are gas imaging images generated using a schlieren imaging system. A piece of dry ice was held near the two ultrasonic speakers with tweezers. When the ultrasonic speakers were off, cold air generated by the dry ice dripped vertically downwards (the cold air is condensed gas formed by the condensation of water vapor in the air due to the low temperature of the dry ice). When the ultrasonic speakers were on, a standing wave field was generated between the two speakers. Because the sound pressure at the nodes is lower than at the antinodes, the condensed gas was drawn into the channel formed by the nodes and compressed at the nodes by the relatively high pressure formed by the antinodes at both ends. This demonstrates that the gas is compressed and enriched.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A detection method for an ultrasonic standing wave sample cell used in infrared spectroscopy, characterized in that, Includes the following steps: Step 1: Select the ultrasonic frequency ω according to the properties of the sample to be tested, and calculate the sound wavelength λ using the formula λ=v / ω, where v is the speed of sound; adjust the distance between the two ultrasonic loudspeakers (2) to nλ / 2, and set the initial phase difference between the two ultrasonic loudspeakers (2) to 180°, where n is an integer ≥1; Step 2: With the ultrasonic speaker (2) in the off state, place the test sample in the sample, which includes liquid sample, solid sample and gas sample; For liquid samples, the ultrasonic standing wave sample cell is covered with an acrylic transparent sealing cover to make the ultrasonic standing wave sample cell a closed space. A heating plate is placed in the acrylic transparent sealing cover and heated to 70°C. A through hole is opened on the acrylic transparent sealing cover. When the ultrasonic speaker (2) is in the off state, the liquid sample to be tested is dropped onto the heating plate with a needle so that the liquid sample evaporates in the sealing cover. After the liquid sample has fully evaporated, the infrared spectrum is scanned. When the ultrasonic speaker (2) is in the on state, the same volume of liquid sample is injected, and the infrared spectrum is scanned after the liquid sample has fully evaporated to obtain infrared spectral data. For solid samples, the powder sample is pressed into the potassium bromide sheet (8) and fixed in the detection area of ​​the speaker bracket (6). The ultrasonic speaker (2) is turned on. After the acoustic standing wave field has been running stably for 20 seconds, the infrared spectrometer is used to scan and obtain infrared spectral data. For gas samples, the ultrasonic standing wave sample cell is covered with an acrylic transparent sealing cover to make the ultrasonic standing wave sample cell a closed space. A heating plate is placed in the sealing cover and heated to 70°C. A through hole is opened on the sealing cover, and the gas sample to be tested is injected into the through hole. Then the ultrasonic loudspeaker (2) is turned on to form an acoustic standing wave field at a preset frequency ω and phase difference. After the acoustic standing wave field has been running stably for 20s to achieve the compression and enrichment of the gas sample, an infrared spectrometer is used to scan and obtain infrared spectral data.

2. The detection method of an ultrasonic standing wave sample cell for infrared spectroscopy detection according to claim 1, characterized in that, The ultrasonic frequency ω in step 1 ranges from 30 to 50 kHz, corresponding to an antinode or node width of 2.5 mm to 4.3 mm.

3. The detection method of an ultrasonic standing wave sample cell for infrared spectroscopy detection according to claim 1, characterized in that, In step 1, the initial phase difference adjustment of the two ultrasonic speakers (2) is achieved by PWM power supply. By switching the phase angle of the two ultrasonic speakers (2), the position of the antinode is controlled to be located in the center or edge region of the ultrasonic speaker (2).

4. An ultrasonic standing wave sample cell for infrared spectroscopy detection, characterized in that, It includes a frame (1), an upper rotating cover (5) and a speaker bracket (6). The upper rotating cover (5) is installed on the top of the frame (1), and the speaker bracket (6) is installed on the bottom of the upper rotating cover (5). An ultrasonic speaker (2) is installed inside the speaker bracket (6). The frame (1) includes a supporting base plate (101) and a top plate (103). The supporting base plate (101) and the top plate (103) are connected to each other by a connecting column (102). An arc-shaped through groove (1031) is provided on the top plate (103). The upper rotating cover (5) is installed inside the limiting member (1032), and a rotating handle (502) is installed on the upper rotating cover (5). A square through hole (5011) is symmetrically arranged on the upper rotating cover (5). The speaker bracket (6) has a speaker mounting hole (6011) inside, and the ultrasonic speaker (2) is installed in the speaker mounting hole (6011). A square tenon (602) is fixedly connected to the top of the speaker bracket (6), and the speaker bracket (6) is connected to the square through hole (5011) on the upper rotating cover (5) through the square tenon (602).

5. The ultrasonic standing wave sample cell for infrared spectroscopy detection according to claim 4, characterized in that, The top plate (103) is fixedly connected to a symmetrically arranged limiting member (1032) at its upper end, and a limiting slot (10321) is formed in the limiting member (1032).

6. The ultrasonic standing wave sample cell for infrared spectroscopy detection according to claim 5, characterized in that, The upper rotating cover (5) has symmetrically arranged flanges (5012), and the upper rotating cover (5) is engaged with the limiting groove (10321) through its flanges (5012).

7. The ultrasonic standing wave sample cell for infrared spectroscopy detection according to claim 4, characterized in that, A wiring hole A (1033) is provided in the middle of the top plate (103), a wiring hole B (5021) is provided on the rotating handle (502), and a wiring hole C (6021) is provided on the square tenon (602). Wiring holes A (1033), B (5021) and C (6021) are all used for wiring of the ultrasonic speaker (2).

8. The ultrasonic standing wave sample cell for infrared spectroscopy detection according to claim 4, characterized in that, The support base plate (101) has a threaded hole (1011) with a diameter of 6mm, which is used for the installation and positioning of the frame (1) and the infrared spectrometer.

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