Infrared spectrum detection method and ultrasonic standing wave sample cell for detection

Abstract

The invention relates to the technical field of spectrum detection, in particular to an infrared spectrum detection method and an ultrasonic standing wave sample cell for detection, the infrared spectrum detection method comprises a frame body, an upper rotary cover and a loudspeaker support, the upper rotary cover is mounted at the top of the frame body, the loudspeaker support is mounted at the bottom of the upper rotary cover, and an ultrasonic loudspeaker is mounted in the loudspeaker support; the frame body comprises a supporting bottom plate and a top plate, the supporting bottom plate and the top plate are connected through a connecting column, and an arc-shaped through groove is formed in the top plate. The ultrasonic standing wave field is introduced into infrared spectrum detection and is applied to the infrared spectrum detection sample pool, the sensitivity and the resolution ratio of a spectrum signal are enhanced through the ultrasonic standing wave effect, large-scale transformation does not need to be conducted on an existing infrared spectrum instrument in design, operation is easy and convenient, maintenance is easy, and the method is suitable for popularization and application. The defect that the influence of the vibration state of sample molecules is neglected when the structure of the sample pool is adjusted in the prior art is overcome, and the spectral response efficiency and the signal quality of the sample in infrared spectroscopic analysis are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of spectrum detection, in particular to an infrared spectrum detection method and an ultrasonic standing wave sample pool for detection. Background Art

[0002] Currently, infrared spectroscopy is widely used in fields such as composition analysis, structural identification, and quality control of solid samples. Its advantages include being non-destructive, rapid, and sensitive, making it particularly popular in industries such as 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 a detachable connector, multiple samples can be placed simultaneously, avoiding the introduction of moisture caused by frequent opening and closing, thereby improving test stability. Patent CN201810043788.2 discloses a high-pressure in-situ infrared sample cell that can measure the infrared spectrum of a CO2-organic liquid system under a high pressure of 10MPa, 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. The design of the plug-in structure facilitates the replacement and cleaning of the sample cell.

[0004] The aforementioned patent primarily performs spectral detection by changing and designing the appearance and structure of the sample cell. It fails to incorporate ultrasonic standing wave fields into spectral analysis and ignores the influence of the molecular vibrational state of the sample. Traditional infrared spectroscopy relies on the absorption signal generated by the natural vibrations of the 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 or intermolecular interactions (such as hydrogen bonds and van der Waals forces), resulting in a significant reduction in signal intensity. Existing sample cell designs only provide a passive detection environment and do not actively enhance molecular vibrations or regulate vibrational modes through external means. This results in signals from low-concentration components or weak interactions being masked by noise.

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

[0006] The present invention aims to provide an infrared spectroscopy detection method and an ultrasonic standing wave sample cell for use therein. By introducing an ultrasonic standing wave field, the method improves the response efficiency and signal quality of samples in infrared spectroscopy detection, thereby addressing the shortcomings of prior art techniques that ignore the influence of the molecular vibrational state of the sample by adjusting the sample cell structure. This sample cell utilizes the ultrasonic standing wave effect to significantly enhance the sensitivity and resolution of spectral signals, 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 technical problems is: A detection method for an ultrasonic standing wave sample cell for infrared spectrum detection comprises the following steps: Step 1: Select the ultrasonic frequency ω based on the properties of the sample to be tested, and calculate the acoustic wavelength λ using the formula λ=v / ω, where v is the speed of sound. Adjust the spacing 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. Step 2: When the ultrasonic speaker is in a turned-off state, detecting a sample, the sample including a liquid sample, a solid sample, and a gas sample; For liquid samples, the ultrasonic standing wave sample cell is covered with a transparent acrylic sealing cover so that the ultrasonic standing wave sample cell is in a closed space. A heating plate is placed in the sealing cover and heated to 70°C. A through hole is opened in the sealing cover, and the liquid sample to be tested is dropped onto the heating plate with a needle to evaporate the liquid sample. After the liquid sample is evaporated, it is scanned using an infrared spectrometer to obtain infrared spectrum data; For solid samples, press the powder sample into a potassium bromide tablet, fix it in the detection area of the speaker bracket, turn on the ultrasonic speaker, wait for the acoustic standing wave field to run steadily for 20 seconds, and then use an infrared spectrometer to scan and obtain infrared spectrum data; For gas samples, the ultrasonic standing wave sample cell is covered with an acrylic transparent sealing cover so that the ultrasonic standing wave sample cell is in a confined 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 detected 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 the preset frequency ω and phase difference. After the acoustic standing wave field runs stably for 20 seconds to achieve compression and enrichment of the gas sample, it is scanned using an infrared spectrometer to obtain infrared spectral data.

[0008] Furthermore, the ultrasonic frequency ω in step 1 ranges from 30 to 50 kHz, corresponding to a width of an antinode or node of 2.5 mm to 4.3 mm.

[0009] Furthermore, the initial phase difference adjustment of the two ultrasonic speakers in step 1 is achieved through a PWM power supply, and the antinode position is controlled to be located in the center or edge area of the ultrasonic speaker by switching the phase angles of the two ultrasonic speakers.

[0010] The present invention also provides an ultrasonic standing wave sample cell for infrared spectrum detection, comprising a frame, an upper rotating cover and a speaker bracket, wherein the upper rotating cover is mounted on the top of the frame, the speaker bracket is mounted on the bottom of the upper rotating cover, and an ultrasonic speaker is mounted in the speaker bracket; The frame includes a supporting bottom plate and a top plate, the supporting bottom plate and the top plate are connected to each other through a connecting column, and an arc-shaped through groove is opened on the top plate; The upper rotating cover is installed in the limiting member, a rotating handle is installed on the upper rotating cover, and symmetrically arranged square through holes are opened on the upper rotating cover; A speaker mounting hole is provided in the speaker bracket, 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 provided on the upper rotating cover through the square tenon.

[0011] Furthermore, a symmetrically arranged limiting member is fixedly connected to the upper end of the top plate, and a limiting slot is provided in the limiting member.

[0012] Furthermore, the upper rotating cover has symmetrically arranged flanges, and the upper rotating cover is engaged with the limiting slots through the flanges.

[0013] Furthermore, a wiring hole A is opened in the middle of the top plate, a wiring hole B is opened on the rotating handle, and a wiring hole C is opened on the square tenon. The wiring holes A, B and C are all used for routing the ultrasonic speaker lines.

[0014] Furthermore, a threaded hole with a diameter of 6 mm is opened on the supporting base plate for installation and positioning of the frame and the infrared spectrometer.

[0015] The advantages of the present invention are: 1. The present invention introduces an ultrasonic standing wave field into infrared spectrum detection and applies the ultrasonic standing wave field to the infrared spectrum detection sample cell. The sensitivity and resolution of the spectral signal are enhanced by the ultrasonic standing wave effect. From the Fourier transform infrared spectrum detection results of ethanol and indium oxide ( Figure 7 and Figure 8 ) shows that the presence of ultrasonic standing waves significantly enhances the spectral signal, making the detection results more accurate and clear. Furthermore, this sample cell is adaptable to samples of various forms, and the ultrasonic standing wave field can enhance the detection of samples in complex systems, making it widely applicable. Furthermore, the design does not require large-scale modifications to existing infrared spectrometers, making it simple to operate and maintain. This addresses the shortcomings of existing technologies that ignore the influence of the sample molecular vibrational state by adjusting the sample cell structure, thereby improving the spectral response efficiency and signal quality of samples in infrared spectroscopy analysis.

[0016] 2. The present invention has an adjustable structure, and the angle and spacing of the ultrasonic speakers can be adjusted by rotating the upper rotating cover. The spacing of the ultrasonic speakers in the sample pool can be adjusted between 14.5mm and 10mm, and the action angle of the ultrasonic standing wave field can be changed between 0 and 90 degrees. It can adapt to different experimental conditions and sample characteristics, and improve the versatility of the sample pool. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a schematic diagram of the airtightness test principle of the present invention.

[0019] Figure 2 for Figure 1 Schematic diagram of the local enlarged structure.

[0020] Figure 3 The figure is a schematic structural diagram of an ultrasonic standing wave sample cell for infrared spectrum detection according to the present invention.

[0021] Figure 4 It is an enlarged structural diagram of the upper rotating cover in the present invention.

[0022] Figure 5 It is an enlarged structural diagram of the frame in the present invention.

[0023] Figure 6 It is a schematic diagram of the enlarged structure of the loudspeaker bracket in the present invention.

[0024] Figure 7 This is the Fourier transform infrared spectrum of ethanol in the sealed sample cell.

[0025] Figure 8 Fourier transform infrared spectra of indium oxide with and without ultrasound action.

[0026] Figure 9 Schematic diagram of two opposing sounding speakers with a distance of 3 and a half wavelengths.

[0027] Figure 10 Schematic diagram of two opposing sound-emitting speakers with a distance of 2 and a half wavelengths.

[0028] Figure 11 This is the schematic diagram of the Schlieren imaging system.

[0029] Figure 12A schematic diagram of the sound pressure distribution and energy density of the standing wave field under different spacing conditions obtained through simulation.

[0030] Components include: 1. Frame; 101. Support base; 1011. Threaded hole; 102. Connecting column; 103. Top plate; 1031. Arc-shaped through-slot; 1032. Positioning member; 10321. Positioning slot; 1033. Wiring hole A; 2. Ultrasonic speaker; 3. Detector; 4. Infrared light source; 5. Upper rotating cover; 501. Cover; 5011. Square through-hole; 5012. Flange; 502. Rotating handle; 5021. Wiring hole B; 6. Speaker bracket; 601. Bracket body; 6011. Speaker mounting hole; 602. Square tenon; 6021. Wiring hole C; 7. Capillary tube; 8. Potassium bromide tablet. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0032] In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. The terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Example 1: Figure 1 This is a schematic diagram of the airtightness test principle of the present invention; Figure 2 for Figure 1 Schematic diagram of a local enlarged structure; Figure 3 This is a schematic structural diagram of an ultrasonic standing wave sample cell for infrared spectrum detection according to the present invention; Figure 4 Schematic diagram of the enlarged structure of the upper rotating cover 5 in the present invention; Figure 5 It is an enlarged structural diagram of the frame 1 in the present invention; Figure 6 FIG. 6 is an enlarged structural diagram of the speaker bracket 6 in the present invention; Figures 1 to 6 The ultrasonic standing wave sample cell for infrared spectrum detection shown in the figure includes a frame 1, an upper rotating cover 5 and a speaker bracket 6, the upper rotating cover is installed on the top of the frame 1, the speaker bracket 6 is installed on the bottom of the upper rotating cover 5, and an ultrasonic speaker 2 is installed in the speaker bracket 6; the ultrasonic speaker bracket 6 in the present invention is suitable for the installation of an ultrasonic speaker 2 with a diameter of 10 mm, a speaker mounting hole 6011 is opened in the speaker bracket 6, and the ultrasonic speaker 2 is installed in the speaker mounting hole 6011, the speaker bracket 6 includes a bracket body 601, a square tenon 602 is fixedly connected to the top of the bracket body 601, the speaker bracket 6 is connected to the square through hole 5011 opened on the upper rotating cover 5 through the square tenon 602, the square tenon 602 on the upper part of the speaker bracket 6 can be connected to the square through hole 5011 of the upper rotating cover 5, and a wiring hole C6021 with a diameter of 4 mm is opened on the square tenon 602 for wiring the line of the ultrasonic speaker 2.

[0034] The frame 1 of the present invention includes a supporting base plate 101 and a top plate 103, which are connected to each other via a connecting column 102. A wiring hole A1033 is provided in the middle of the top plate 103 for routing the ultrasonic speaker 2 wiring. The frame 1 of the present 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 mounting and positioning the frame 1 and an infrared spectrometer (not shown). Furthermore, a groove can be provided on the bottom surface of the frame 1, and a ceramic heating plate can be placed in the groove to heat the atmosphere sample in an airtight environment. The present invention also provides an arc-shaped through-slot 1031 with a width of 10mm and an angle of 120 degrees on the top plate 103. Its purpose is to achieve rotational movement of the ultrasonic speaker bracket 6 after installation. In addition, a symmetrically arranged limit member 1032 is fixedly connected to the upper end of the top plate 103, and a limit slot 10321 is provided in the limit member 1032 for limiting the upper rotating cover 5, thereby fixing the position of the upper rotating cover 5 during the rotational movement.

[0035] The upper rotating cover 5 in the present invention is installed in the limiting member 1032. A rotating handle 502 is installed on the upper rotating cover 5. There is a square through hole 5011 with a side length of 7 mm at each symmetrical position 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. The upper rotating cover 5 is mutually engaged with the limiting slot 10321 through its flanges 5012. A groove with a width of 3.7 mm and an angle of 60 degrees is respectively opened on both sides of the upper rotating cover 5. The groove is located between the two flanges 5012. Its function is to adapt to and install the overall frame 1. The rotating handle 502 (such as Figure 4 As shown, including the cylindrical support structure, wiring holes B5021 with a diameter of 6 mm are respectively opened for routing the lines of the ultrasonic speaker 2.

[0036] 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 accordingly according to the experimental conditions, and the adjustment range is 14.5 mm to 10 mm. By rotating the handle 502 and through the arc-shaped groove 1031 opened on the top plate 103, the angular position of the ultrasonic standing wave field acting on the surface of the sample material can be changed between 0 and 90 degrees.

[0037] Figure 7 This is the Fourier infrared spectrum of ethanol in the sealed sample cell. Figure 8 The following are Fourier infrared spectra of indium oxide with and without ultrasound action. When conducting the airtightness experiment, acrylic plates are first installed around the sample cell to achieve sealing. Circular windows with a diameter of 20 mm are opened on the two opposite panels through which infrared light passes, and barium fluoride windows are used for installation and sealing to ensure good transmittance of the infrared beam (not shown in the figure, for illustration). Figure 7 The figure shows the Fourier transform infrared spectrum of ethanol in a sealed sample cell. The dotted line indicates the case without ultrasonic standing wave effect, while the solid line indicates the case with ultrasonic standing wave effect.

[0038] The principle diagram when conducting sample testing is as follows Figure 8 As shown, the experimental method is the same as the airtightness experiment. A capillary 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 7. The capillary 7 is used to fix the position of the potassium bromide sheet 8. The potassium bromide sheet 8 is a carrier of the test sample to ensure that the potassium bromide sheet 8 passes through the propagation path of the infrared light path. Figure 8 The figure shows the Fourier transform infrared spectrum of indium oxide in a sealed sample cell. The dotted line indicates the absence of ultrasonic standing waves, while the solid line indicates the presence of ultrasonic standing waves.

[0039] Regarding ultrasonic speaker mounting, in addition to using the ultrasonic speaker bracket 6 in this solution, a magnetic mounting structure could be considered, using magnetic materials to secure the ultrasonic speaker in place. This would facilitate replacement. Regarding sample cell sealing, in addition to using acrylic sheets and barium fluoride windows, new sealants or films could be explored to further enhance the sample cell's sealing while ensuring infrared light transmittance.

[0040] The present invention also provides a detection method of an ultrasonic standing wave sample cell for infrared spectrum detection, comprising the following steps: Step 1: Select the ultrasonic frequency ω based on the properties of the sample to be tested, and calculate the acoustic wavelength λ using the formula λ=v / ω, where v is the speed of sound. To form a stable acoustic standing wave field, the distance between the two speakers must be an integer multiple of half the wavelength, i.e., distance = nλ / 2. The initial phase difference between the two ultrasonic speakers is set to 180°, where n is an integer ≥ 1. This ensures that a node is the weakest point of resonance, while an antinode is the strongest point of resonance. A node and an antinode are defined as a single point, extending λ / 8 from their respective centers to either end, meaning the width of both nodes 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 angles of the two ultrasonic speakers, the antinodes are positioned at the center or edge of the ultrasonic speakers. Figure 9 The diagram shows that the distance between two relative ultrasonic speakers is 3 times half wavelength, as shown in Figure 9 As shown in the figure, 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 phase of the two ultrasonic speakers is adjusted, the initial phase of ultrasonic speaker 1 is 90° and the initial phase of ultrasonic speaker 2 is -90°, the center position can be adjusted to the node.

[0041] Figure 10 The diagram below shows a situation where the distance between two relative sounding speakers is 2 and a half wavelengths. Figure 10 As shown in the figure, after adjusting the distance between the two ultrasonic speakers, when the distance between the two ultrasonic speakers is 2 times half the wavelength, the relative distance between the center of the node and the antinode is still λ / 4, and the width of the node and the antinode is still λ / 4. Figure 9 The principle is the same as in [1]. The initial phase of ultrasonic speaker 1 is 0°, the initial phase of ultrasonic speaker 2 is 180°, and the center position of the two ultrasonic speakers is the antinode. By adjusting the initial phase of the two ultrasonic speakers, the initial phase of ultrasonic speaker 1 is 90°, and the initial phase of ultrasonic speaker 2 is -90°, the center position can be adjusted to the node.

[0042] By analogy, while 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 to ensure that the initial phases of the two ultrasonic speakers differ by 180°. By adjusting the initial phases of the two ultrasonic speakers, the positions of the nodes and antinodes can be adjusted.

[0043] Step 2: For liquid samples, drop the liquid sample onto a 70°C hot plate to evaporate it, forming a test environment with uniform gas concentration; Figure 1 The ultrasonic standing wave sample pool is covered with an acrylic transparent sealing cover to ensure that the ultrasonic device is in a closed space. A light inlet and a light outlet are set on the acrylic transparent sealing cover. The light inlet is made of potassium bromide material to ensure that the infrared light passes through without losing energy. A heating plate is placed in the sealing cover and the temperature is controlled at 70 degrees. A small hole is opened on the sealing cover, and a needle is used to drop the liquid sample to be tested onto the heating plate to evaporate the liquid sample. In this way, the gas concentration in the space can be changed by changing the amount of liquid sample in the same volume space. When the speaker is in the off state, a certain volume of ethanol is injected to evaporate the ethanol in the sealing cover. After the ethanol is fully evaporated for 50 seconds after it is dripped, the infrared spectrum is scanned to obtain Figure 7 When the speaker is turned on, the same volume of ethanol is injected and the infrared spectrum is scanned after the ethanol is fully evaporated 50 seconds after it is dripped. Figure 7 The solid line in the image is clearly visible. The signal intensity of the solid spectral peak has nearly doubled, indicating that ethanol vapor is compressed and concentrated under the ultrasonic standing wave field. This observation, along with schlieren imaging, supports this observation. 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 increases the sensitivity of the instrument and enables the detection of water vapor in the air. The peaks at 1550 cm-1 and 1700 cm-1 originate from the angular vibration of H2O, the peak at 3700 cm-1 from the antisymmetric stretching vibration of H2O, and the peak at 3800 cm-1 from the symmetric stretching vibration of H2O. Specifically, using CO2 gas as a sample, at 40 kHz sound waves, with an anti-node spacing of 4.3 mm and a pressure difference of 500 Pa, the gas concentration increases by 80%. The infrared absorption peak at 2349 cm-1 increases threefold in intensity, and a new peak at 2375 cm-1 (corresponding to excited-state vibrations) appears.

[0044] Figure 8 The Fourier infrared spectra of indium oxide with and without ultrasound action are shown in Figure 2. Figure 8 As shown, when the ultrasonic speaker is in the off state, the infrared spectrum is traced and the result is Figure 8The powder sample is pressed into the potassium bromide sheet and fixed to the detection area of the speaker bracket. The ultrasonic speaker is turned on to form an acoustic standing wave field at the preset frequency ω and phase difference. The sound wave is kept stable for 20 seconds, so that the molecular structure of the solid sample is regulated by the sound wave. Figure 8 From the solid line in the figure, it can be clearly seen that the two spectral peaks at 750cm-1 and 1070cm-1 are significantly enhanced under the action of the acoustic standing wave field. The peak at 750cm-1 represents O- ions (negative oxygen ions) and the peak at 1070cm-1 represents O2- ions (superoxide ions). The peak values of superoxide ions and negative oxygen ions gradually increase with the action of ultrasound. After analyzing this phenomenon, the following conclusions were drawn: The mechanism of the influence of ultrasonic standing waves on the oxygen partial pressure of the system shows a unique regularity. Due to the weakening of the interaction between gas molecules, the change in energy transfer and distribution in the ultrasonic standing wave field has a more significant regulatory effect on the motion state of oxygen molecules, which in turn directly affects the oxygen partial pressure of the system. In a low-concentration environment, a higher oxygen partial pressure (relative to the background low concentration conditions) provides a thermodynamic advantage for the adsorption of oxygen atoms on the surface of the indium oxide material, prompting the activated adsorption of oxygen molecules: When oxygen atoms are adsorbed on the surface of indium oxide, oxygen vacancies are formed in the lattice. The impact of this process on the electronic structure of the material is amplified under low concentration conditions: due to the low carrier concentration of indium oxide itself, the consumption of electrons in the reaction directly leads to a significant decrease in the internal carrier concentration, which in turn causes the resistance of the sensing material to rise rapidly. As the action time of the acoustic standing wave field increases, the adsorption process shows a cumulative effect. More oxygen atoms break through the adsorption energy barrier with the energy assistance of the standing wave field, causing the oxygen vacancy concentration to gradually increase, the electron consumption to intensify, and the sensor resistance to continue to rise. This microscopic change is manifested in the infrared spectrum as the vibration peaks of superoxide ions and negative oxygen ions gradually increase with the increase in adsorption amount, reflecting the directional regulation of the acoustic standing wave on the adsorption behavior of gas molecules.

[0045] For gas samples, the ultrasonic standing wave sample cell is covered with an acrylic transparent sealing cover so that the ultrasonic standing wave sample cell is in a confined 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 to evaporate the liquid sample. Then, the ultrasonic speaker is turned on to form an acoustic standing wave field at the preset frequency ω and phase difference. After the acoustic standing wave field runs stably for 20 seconds to achieve compression and enrichment of the gas sample, it is scanned using an infrared spectrometer to obtain infrared spectral data. Figure 11 The schematic diagram of the Schlieren imaging system is as follows: Figure 11The schlieren imaging system shown includes a camera, a filter, a concave reflector, and a point light source. The point light source is placed parallel to the filter at a position twice the focal length of the concave reflector. The camera is placed behind the filter for image reception. This system can amplify the light refraction phenomenon caused by the different gas concentrations due to temperature differences through the concave reflector. It is generated based on the refraction phenomenon of light in different media. When light propagates in a uniform spatial medium, it moves in a straight line. This is because the physical properties of the medium remain consistent in space without causing changes in 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: , where n1 and n2 represent the refractive indices of the two media, and θ1 and θ2 are the incident angle and refraction angle of the light on the incident surface, respectively.

[0046] Figure 12 The following is a schematic diagram of the sound pressure distribution and energy density of the standing wave field under different spacing conditions obtained by simulation, as shown in the figure: Figure 12 As shown in the figure on the far left, a detailed simulation was performed using 3D AcousticSIM software. Through the simulation, key parameters such as the sound pressure distribution and energy density of the standing wave field under different spacing conditions were obtained. The simulation used a frequency of 40 kHz, and the distance between the two ultrasonic speakers was 1.5 times the wavelength. The middle and right figures are gas imaging images generated by a schlieren imaging system. A piece of dry ice was held with tweezers and placed close to the two ultrasonic speakers. When the ultrasonic speakers were turned off, cold air generated by the dry ice dripped vertically downward (the cold air is condensed gas caused by the low temperature of the dry ice and water vapor in the air). When the ultrasonic speakers were turned on, a standing wave field was generated between the two ultrasonic speakers. Because the sound pressure at the nodes is lower than that at the antinodes, the condensed gas is 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 the compression and enrichment of the gas.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements 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 for infrared spectrum detection, characterized in that: The following steps are involved: Step 1: Select the ultrasonic frequency ω according to the properties of the sample to be tested, and calculate the acoustic wavelength λ by the formula λ=v / ω, where v is the speed of sound; adjust the distance between the two ultrasonic speakers (2) to nλ / 2, and set the initial phase difference between the two ultrasonic speakers (2) to 180°, where n is an integer ≥1; Step 2: When the ultrasonic speaker (2) is in a closed state, detecting a sample, the sample including a liquid sample, a solid sample and a gas sample; For liquid samples, the ultrasonic standing wave sample cell is covered with a transparent acrylic sealing cover so that the ultrasonic standing wave sample cell is in a closed space. A heating plate is placed in the sealing cover and heated to 70°C. A through hole is opened in the sealing cover, and the liquid sample to be tested is dropped onto the heating plate with a needle to evaporate the liquid sample. After the liquid sample is evaporated, it is scanned using an infrared spectrometer to obtain infrared spectrum data; For solid samples, press the powder sample into a potassium bromide sheet (8), fix it in the detection area of the speaker bracket (6), turn on the ultrasonic speaker (2), wait for the acoustic standing wave field to run stably for 20 seconds, and then use an infrared spectrometer to scan and obtain infrared spectrum data; For gas samples, the ultrasonic standing wave sample pool is covered with an acrylic transparent sealing cover so that the ultrasonic standing wave sample pool is in 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 to evaporate the liquid sample. Then, the ultrasonic speaker (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 runs stably for 20 seconds to achieve compression and enrichment of the gas sample, it is scanned using an infrared spectrometer to obtain infrared spectrum data.

2. The detection method of an ultrasonic standing wave sample cell for infrared spectrum detection according to claim 1, characterized in that: The ultrasonic frequency ω in step 1 is in the range of 30-50 kHz, corresponding to a wave antinode or wave node width of 2.5 mm-4.3 mm.

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

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

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

6. The ultrasonic standing wave sample cell for infrared spectrum detection according to claim 5, characterized in that: The upper rotating cover (5) is provided with symmetrically arranged flanges (5012), and the upper rotating cover (5) is mutually engaged with the limiting clamping groove (10321) via the flanges (5012) thereof.

7. The ultrasonic standing wave sample cell for infrared spectrum detection according to claim 4, characterized in that: A wiring hole A (1033) is provided at the middle position 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). The wiring hole A (1033), the wiring hole B (5021) and the wiring hole C (6021) are all used for wiring the ultrasonic speaker (2).

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

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