A method and system for collecting soil volatile

Abstract

The present application relates to the field of soil environment monitoring, and specifically discloses a soil volatile substance collection method and system, the method comprising: projecting modulated near-infrared light to a soil microzone, coupling an acoustic pressure pulse to induce cavitation effect of a pore liquid film; using the modulated near-infrared light as detection light to collect characteristic absorption spectrum attenuation, and determining the microzone gas phase saturation enrichment state; constructing a non-uniform light field and a directional temperature gradient to form a vapor pressure gradient and thermophoresis effect; setting a multi-stage condensation trap covered with a light-thermal response type micro-nano structure array at a cold end to obtain a graded captured substance; collecting a fluorescence excitation-emission matrix spectrum, comparing it with a standard fluorescence fingerprint characteristic library to generate a correction signal, and feeding back to adjust to form a full-chain closed-loop collection; the system comprises three functionally matched modules. The present application realizes in-situ selective desorption, undisturbed directional migration, selective condensation capture and molecular-level optical purity closed-loop correction of soil volatile substances, and improves the collection purity and efficiency.

Description

Technical Field

[0001] This invention relates to the field of soil environmental monitoring technology, specifically to a method and system for collecting volatile substances in soil. Background Technology

[0002] Soil volatile organic compounds (VOCs) are key indicators for assessing soil environmental quality and ecological safety, and their accurate collection is crucial for subsequent qualitative and quantitative analysis. Current VOC collection technologies primarily employ mechanical drilling combined with overall heating and stirring, using an air pump to introduce volatile gases into a collection container. While this method, centered on overall heating, can promote VOC release to some extent, it inevitably disrupts the original soil matrix structure, leading to the co-release of large amounts of non-target interfering substances and poor collection selectivity. Furthermore, the collection process relies on air pump purging to create forced convection, which easily disrupts the gas-phase equilibrium in soil micro-zones, causing diffusion loss of target substances. Additionally, there is a lack of in-situ real-time methods for determining the enrichment level of gas phase in micro-zones, resulting in a mismatch between migration driving forces and gas phase concentration, leading to low collection efficiency.

[0003] Another technical solution relies on pre-set environmental parameter models for sampling point planning. While this can establish a sampling network at a macro level, it is insufficient in responding to the heterogeneity of soil micro-regions, making it difficult to achieve accurate in-situ sampling. Yet another technical solution integrates multi-source information and inputs it into a regression prediction model, focusing on inferring the content after sampling rather than controlling the purity and optimizing parameters during the sampling process itself. This results in poor sampling repeatability and weak field adaptability.

[0004] More importantly, current technologies have not addressed the deep physical bottlenecks in soil micro-area collection. Volatile substances in soil pores are bound by the surface tension of capillary water films, forming liquid bridges that create a locking effect. Traditional single thermal excitation methods struggle to overcome this interfacial barrier, leading to incomplete desorption. The mean free path of gas molecules within soil micropores is comparable to the pore size, placing them in the Knudsen diffusion-dominated region. Under conventional pressure, molecules frequently collide with the pore walls, resulting in significant migration resistance and a Knudsen trap effect. During multi-stage condensation capture, high-boiling-point substances preferentially form liquid films on the surface of the low-temperature trap, hindering the effective condensation of low-boiling-point substances and causing co-condensation interface contamination. Fourthly, the lack of in-situ optical verification methods for the entire desorption, migration, and capture chain makes the collection process uncontrollable and purity difficult to guarantee.

[0005] Therefore, there is an urgent need for a soil volatile matter collection method that can achieve breakthroughs in liquid bridge locking through photothermal-acoustic-pressure synergy, avoid Knudsen traps through thermophoretic vapor pressure gradient synergy, selectively avoid co-condensation pollution through photothermal-responsive micro-nano structures, and achieve closed-loop correction of the entire chain through in-situ verification of fluorescence excitation emission matrix. Summary of the Invention

[0006] The technical problem to be solved by this invention is the poor selectivity, large migration loss, low purity and uncontrollable process of soil volatile substance collection caused by capillary bridge locking, Knudsen diffusion resistance in micropores and co-condensation contamination at the condensation interface.

[0007] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for collecting volatile substances in soil, specifically including the following steps:

[0008] S1. Project modulated near-infrared light into the soil micro-region and couple it with a sound pressure pulse to induce cavitation effect of pore liquid film and destroy capillary liquid bridge binding; use the modulated near-infrared light as the detection light to collect the characteristic absorption spectrum intensity attenuation when it passes through the gas phase of the micro-region and determine the saturated enrichment state of the gas phase of the micro-region.

[0009] S2. Based on the gas-phase saturated enrichment state of the micro-region, a non-uniform light field and a directional temperature gradient are constructed to form a vapor pressure gradient and a thermophoretic effect; a multi-level condensation trap covered with a photothermal response micro-nano structure array is set at the cold end collection port to realize gradient condensation capture and obtain graded captured substances.

[0010] S3. Project a broadband detection beam onto the graded captured material, collect the characteristic fluorescence excitation-emission matrix spectrum, and compare it with the standard fluorescence fingerprint feature library to verify the optical purity; generate a correction signal based on the purity comparison deviation, and use feedback to adjust the near-infrared light power density, acoustic pressure pulse coupling strength, non-uniform light field intensity, thermophoretic temperature gradient, and multi-stage condenser photothermal excitation parameters to form a closed-loop acquisition chain.

[0011] Based on the above technical solution, the present invention can be further improved as follows.

[0012] Furthermore, S1 specifically includes:

[0013] S11. Near-infrared light is projected onto soil micro-areas to establish a light and heat gradient from the surface to the interior in the vertical direction of the micro-areas;

[0014] S12. Synchronously couple acoustic pressure pulses to the same micro-region to induce cavitation effect of pore liquid film, causing volatile substances bound by capillary liquid bridges to be released into the gas phase;

[0015] S13. Set a background reference value, and collect the characteristic absorption spectrum attenuation amount when the modulated near-infrared light passes through the micro-region gas phase in real time. When the rate of change of the attenuation amount within a preset time window is lower than a preset threshold, it is determined that the micro-region gas phase has reached a saturated enrichment state.

[0016] Furthermore, S12 specifically includes:

[0017] S121. The acoustic pressure pulse is coupled to the projection area of ​​the modulated near-infrared light in a phase-synchronized manner, so that the antinode of the acoustic pressure pulse is aligned with the pore liquid film enrichment area of ​​the soil micro-region.

[0018] S122. Transient cavitation bubbles are induced in the liquid film by sound pressure pulses. The cavitation bubbles generate local micro-jet and shock wave at the moment of collapse, which mechanically destroys the solid-liquid interface adhesion of the capillary liquid bridge.

[0019] S123. Control the duration of the sound pressure pulse to 1s to 5s and the pulse interval to 2s to 10s, so that the cavitation effect acts repeatedly on the same micro-region in an intermittent manner, thereby realizing the batch and gradual release of bound volatile substances.

[0020] Furthermore, S13 specifically includes:

[0021] S131. Using the characteristic absorption spectrum intensity before the projection of modulated near-infrared light and before the coupling of sound pressure pulse as the background reference value, set the reference baseline for the rate of change of characteristic absorption spectrum attenuation.

[0022] S132. During the action of the sound pressure pulse, the real-time characteristic absorption spectrum intensity of the modulated near-infrared light passing through the micro-region gas phase is continuously collected at a fixed sampling interval, and the attenuation amount relative to the background reference value at each sampling time is calculated.

[0023] S133. Linearly fit the attenuation at multiple consecutive sampling times within a preset time window to obtain the rate of change of attenuation over time;

[0024] S134. When the rate of change of the attenuation amount over time is lower than a preset threshold, it is determined that the micro-region gas phase has reached a saturated enrichment state, and an enrichment completion signal is generated.

[0025] Furthermore, in S2, based on the micro-region's gas-phase saturated enrichment state, a non-uniform light field and a directional temperature gradient are constructed to form a vapor pressure gradient and a thermophoretic effect, specifically including:

[0026] S21. Based on the gas phase saturation enrichment state of the micro-region, a set of independently controllable laser arrays is activated to generate a non-uniform light field pointing towards the cold end acquisition port above the micro-region, forming a local vapor pressure gradient;

[0027] S22. The Peltier element set on the side wall of the directional migration channel is activated synchronously to generate a directional temperature gradient with a temperature difference of 10°C to 30°C, which induces the enriched gas phase to generate a thermophoretic migration force towards the cold end.

[0028] S23. The enriched gas phase is transported directionally to the cold end collection port along the directional migration channel coated with a hydrophobic fluorocarbon coating on the inner wall under the combined action of vapor pressure gradient and thermophoretic force.

[0029] Furthermore, in step S2, a multi-stage condensation trap covered with a photothermal responsive micro / nano structure array is set at the cold end collection port to achieve gradient condensation capture and obtain graded captured material, specifically including:

[0030] S241. The multi-stage condenser is set as the first stage and the second stage along the migration direction, and the operating temperature of each condenser decreases step by step along the migration direction to capture volatile substances with different boiling ranges respectively.

[0031] S242. The transported gas phase flows sequentially through the first and second stages, and volatile substances with different boiling ranges form selective adsorption-condensation on the surface of the photothermal responsive micro / nano structure. Uncondensed gas is discharged through the exhaust pipe.

[0032] S243. Real-time monitoring of the characteristic spectral intensity of the outlet of the two-stage condenser. When the outlet signal intensity is lower than 20% of the initial inlet signal for 1 minute, it is determined that the target boiling range substance has been basically captured, and a capture completion signal is generated.

[0033] Furthermore, S3 specifically includes:

[0034] S31. Project a broadband detection beam with a wavelength of 200 nm to 600 nm onto the graded captured material, and scan with an excitation step size of 5 nm to 10 nm to collect the fluorescence excitation-emission matrix spectrum in the emission wavelength range of 300 nm to 700 nm.

[0035] S32. Compare the measured fluorescence excitation-emission matrix spectrum with the pre-stored standard fluorescence fingerprint feature library, and calculate the characteristic peak position deviation and peak intensity relative deviation;

[0036] S33. When the position deviation of the characteristic peak is greater than 2nm or the relative deviation of the peak intensity is greater than 10%, a first correction signal is generated and fed back to the modulation of near-infrared light power density and acoustic pressure pulse coupling intensity adjustment end; when a non-standard fingerprint peak appears in the measured spectrum, a second correction signal is generated and fed back to the non-uniform light field intensity, thermophoretic temperature gradient and multi-stage condenser photothermal excitation parameter adjustment end, forming a closed-loop acquisition chain.

[0037] Furthermore, S32 specifically includes:

[0038] S321. Retrieve the standard excitation-emission matrix corresponding to the current target volatile substance from the pre-stored standard fluorescent fingerprint feature library, and extract the excitation wavelength, emission wavelength and standard peak intensity of the standard characteristic peak;

[0039] S322. After removing the background and normalizing the measured fluorescence excitation-emission matrix spectrum, identify the measured characteristic peaks and record the excitation wavelength, emission wavelength and peak intensity of the measured characteristic peaks.

[0040] S323. Calculate the excitation wavelength deviation, emission wavelength deviation, and relative peak intensity deviation between the measured characteristic peak and the standard characteristic peak, where the wavelength deviation is the difference between the measured wavelength and the standard wavelength, and the relative intensity deviation is the percentage of the difference between the measured intensity and the standard intensity relative to the standard intensity.

[0041] Furthermore, S33 specifically includes:

[0042] S331. When the absolute value of the wavelength deviation in the comparison result is greater than 2nm or the relative value of the intensity deviation is greater than 10%, a first correction signal is generated. The first correction signal includes a power increment ΔP and a sound pressure increment ΔS, wherein ΔP is proportional to the absolute value of the wavelength deviation and ΔS is proportional to the relative value of the intensity deviation.

[0043] S332. When a non-standard fingerprint peak appears in the comparison result, a second correction signal is generated. The second correction signal contains an instruction to increase the photothermal excitation power of the multi-stage condenser trap, with an increase of 5% to 20% of the current value.

[0044] S333. The first correction signal is transmitted to the modulation near-infrared light power density adjustment terminal and the sound pressure pulse coupling intensity adjustment terminal respectively, and the photothermal gradient and cavitation effect intensity are increased simultaneously.

[0045] S334. Transmit the second correction signal to the non-uniform light field intensity adjustment end, the thermophoretic temperature gradient adjustment end, and the multi-stage condenser photothermal excitation parameter adjustment end to enhance the light field directivity and the selective capture capability of the condenser. Repeat the S1 to S3 operations until the comparison deviation meets the preset threshold.

[0046] A soil volatile matter collection system, used to implement a method for collecting soil volatile matter, comprising:

[0047] The photothermal acoustic pressure synergistic desorption module is used to project modulated near-infrared light into soil micro-regions, coupled with acoustic pressure pulses to induce cavitation effect of pore liquid film, destroy capillary liquid bridge binding, and cause volatile substances to be synergistically desorbed from the solid-liquid interface and enriched in the micro-region pore gas phase. The modulated near-infrared light is used as the detection light to collect the characteristic absorption spectrum intensity attenuation when it passes through the micro-region gas phase, and to determine the saturated enrichment state of the micro-region gas phase.

[0048] The directional migration selective capture module is used to construct a non-uniform light field and a directional temperature gradient to form a vapor pressure gradient and thermophoretic effect based on the saturated enrichment state of the gas phase in the micro-region. Under the synergistic effect of the vapor pressure gradient and thermophoretic force, the enriched gas phase migrates along the directional migration channel to the cold end collection port. A multi-level condensation trap covered with a photothermal responsive micro-nano structure array is set at the cold end collection port to realize gradient condensation capture and obtain graded captured substances.

[0049] The fluorescence verification closed-loop correction module is used to project a broadband detection beam onto the graded captured material, collect the characteristic fluorescence excitation-emission matrix spectrum, compare it with the standard fluorescence fingerprint feature library to verify optical purity, generate a correction signal based on the purity comparison deviation, and feed back to adjust the modulated near-infrared light power density and acoustic pressure pulse coupling strength of the photothermal acoustic pressure co-desorption module. At the same time, it adjusts the non-uniform light field intensity, thermophoresis temperature gradient, and photothermal excitation parameters of the directional migration selective capture module to form a full-chain closed-loop acquisition.

[0050] The beneficial effects of this invention are:

[0051] 1. By projecting modulated near-infrared light into soil micro-regions to form a depth-direction photothermal gradient, and simultaneously coupling acoustic pressure pulses to induce cavitation effect in pore liquid films, the binding of capillary liquid bridges to volatile substances is mechanically destroyed, breaking the liquid bridge locking effect, achieving selective photothermal desorption and acoustic pressure mechanical bridge breaking synergistically, significantly reducing the co-release of non-target substances, and improving the selectiveness of target volatile substance collection.

[0052] 2. A non-uniform light field is constructed above the micro-region to form a local vapor pressure gradient. A directional temperature gradient is applied to induce a thermophoretic effect, which enables the enriched gas phase to migrate undisturbed and avoids the Knudsen trap effect in the micropores. A multi-level condensation trap covered with a photothermal responsive micro-nano structure array is used to achieve selective gradient condensation through the photothermal evaporation-recondensation equilibrium temperature difference, which suppresses co-condensation contamination and improves the capture purity.

[0053] 3. In-situ verification of fluorescence excitation-emission matrix spectroscopy of graded captured substances is performed, and optical purity is verified by comparison with standard fluorescence fingerprint feature library. Correction signals are generated to feed back and adjust the parameters of photothermal desorption, directional migration and selective capture, forming a closed-loop self-optimization chain, solving the uncontrollable defects in the collection process, and significantly improving the collection purity and repeatability. Attached Figure Description

[0054] Figure 1 These are schematic flowcharts of the methods described in Embodiments 1-4 of the present invention;

[0055] Figure 2 This is a framework diagram of the system described in Embodiment 5 of the present invention;

[0056] Figure 3 This is a schematic diagram of the electronic device in this invention. Detailed Implementation

[0057] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0058] Example 1, such as Figure 1 As shown, the present invention provides a method for collecting volatile substances in soil, specifically including the following steps:

[0059] S1. Project modulated near-infrared light into the soil micro-region and couple it with a sound pressure pulse to induce cavitation effect of pore liquid film and destroy capillary liquid bridge binding; use the modulated near-infrared light as the detection light to collect the characteristic absorption spectrum intensity attenuation when it passes through the gas phase of the micro-region and determine the saturated enrichment state of the gas phase of the micro-region.

[0060] S2. Based on the micro-region gas phase saturation enrichment state, a non-uniform light field and directional temperature gradient are constructed to form a vapor pressure gradient and thermophoretic effect; a multi-level condensation trap covered with a photothermal response micro-nano structure array is set at the cold end collection port to realize gradient condensation capture and obtain graded captured substances;

[0061] S3. Project a broadband detection beam onto the graded captured material, collect the characteristic fluorescence excitation-emission matrix spectrum, and compare it with the standard fluorescence fingerprint feature library to verify the optical purity; generate a correction signal based on the purity comparison deviation, and use feedback to adjust the near-infrared light power density, acoustic pressure pulse coupling strength, non-uniform light field intensity, thermophoretic temperature gradient, and multi-stage condenser photothermal excitation parameters to form a closed-loop acquisition chain.

[0062] Example 2, preferably, in Example 1, step S1 is specifically implemented through the following steps:

[0063] S11. Establishment of the near-infrared photothermal gradient, specifically as follows:

[0064] A near-infrared light source array is fixedly installed directly above a soil micro-region. This array consists of 3 to 5 semiconductor laser diodes or fiber-coupled lasers with independently adjustable output power. The light-emitting units are arranged in a gradient with equal spacing along a direction perpendicular to the soil surface, with the spacing between adjacent units set to 5 mm to 15 mm. The output power of each light-emitting unit is set separately via an independent constant current drive circuit, decreasing progressively from the surface layer to deeper layers. The power density of the surface layer units is set to 0.6 W / cm² to 2 W / cm², and the power density of the deeper layer units is set to 0.1 W / cm² to 0.4 W / cm². The light source drive circuit sinusoidally modulates the near-infrared light with a fixed modulation frequency set within the range of 10 Hz to 100 Hz to distinguish environmental stray light interference and facilitate subsequent phase-locked detection to extract effective signals.

[0065] Modulated near-infrared light is projected onto soil micro-regions. The wavelength of this light is selected within the range of 1.2 μm to 1.8 μm based on the overtone absorption characteristics of carbon-hydrogen bonds and carbon-oxygen bonds in the target volatile substances. After penetrating the soil surface, the near-infrared light is selectively absorbed by specific functional groups in the soil organic matter and converted into heat energy. Due to the higher light power density and relatively rich organic matter content received by the surface soil, the light energy absorption is mainly concentrated in the 0 cm to 2 cm depth range, while the light power density received by the deeper soil is lower, and the heat absorption is correspondingly reduced. This naturally forms a photothermal gradient in the vertical direction of the micro-region, with the surface temperature gradually decreasing from the surface to the interior. The surface temperature is 10°C to 30°C higher than the deep temperature.

[0066] This photothermal gradient causes the soil micro-regions to heat up layer by layer from the surface inwards, inducing volatile substances to thermally desorb from the solid-liquid interface and diffuse into the pore gas phase. The high-temperature surface zone preferentially promotes the release of shallowly bound volatile substances, while the relatively low-temperature deep zone maintains the stability of the soil matrix structure, avoiding the destruction of soil colloids and the co-release of non-target interfering substances caused by uniform heating. By modulating the selective absorption and power gradient configuration of near-infrared light, the target volatile substances are excited layer by layer from the surface inwards, enabling the volatile substances to accumulate in an orderly manner in the pore gas phase of the micro-regions, providing a concentration basis for subsequent gas phase monitoring and targeted migration.

[0067] S12. Acoustic pressure pulse coupling and cavitation desorption, specifically:

[0068] S121. Acoustic pressure pulse phase synchronization coupling and antinode alignment, specifically:

[0069] A piezoelectric ceramic transducer or a magnetostrictive transducer is fixedly installed on the sidewall or directly above the soil micro-region as a sound pressure pulse emission source. The transducer shares the same control unit with the light source array that modulates near-infrared light and achieves phase synchronization by sharing a clock signal. The frequency of the sound pressure pulse is set to 20kHz to 50kHz, which matches the inherent resonant frequency of the pore liquid film in the soil micro-region to maximize the cavitation effect efficiency.

[0070] The acoustic pressure pulse emitted by the transducer is coupled to the projection area of ​​the modulated near-infrared light in a phase-synchronous manner, ensuring that the acoustic energy and photothermal energy overlap in space. By adjusting the geometric position and emission angle of the transducer relative to the soil micro-region, the antinodes of the acoustic pressure pulse are precisely aligned with the pore liquid film enrichment area of ​​the soil micro-region, namely the surface layer from 0 cm to 2 cm depth where capillary liquid bridges are densely distributed. The acoustic pressure amplitude is highest at the antinodes, reaching 0.1 MPa to 0.5 MPa, which can concentrate on the volatile substances bound in the liquid film, while the nodes avoid the soil skeleton structure, reducing unnecessary mechanical damage. This phase-synchronous coupling mechanism ensures that the photothermal gradient and acoustic pressure cavitation are spatiotemporally coordinated in the same micro-region, providing energy superposition conditions for subsequent desorption.

[0071] S122. Transient cavitation bubble induction and capillary liquid bridge mechanical damage, specifically:

[0072] When a sound pressure pulse propagates in the enriched region of a porous liquid film, the presence of dissolved gas and tiny gas nuclei in the liquid film causes the local pressure to be lower than the saturated vapor pressure of the liquid film during the negative pressure phase of the sound wave, inducing the formation of transient cavitation bubbles. These cavitation bubbles rapidly grow to the micrometer scale during the positive pressure phase of the sound wave, and then enter the collapse stage during the periodic pressure changes of the sound pressure pulse. At the moment of collapse, due to the huge pressure difference and surface tension inside and outside the bubble, a local microjet is generated pointing towards the center of the bubble, accompanied by a spherical shock wave radiating to the surrounding liquid film medium.

[0073] The speed of local microjets can reach tens to hundreds of meters per second, directly impacting the solid-liquid interface of the capillary liquid bridge; the shock wave propagates in the liquid film in the form of a pressure wave, causing instantaneous shear stress at the solid-liquid interface. Under the synergistic mechanical action of the microjets and the shock wave, the originally stable solid-liquid interface adhesion of the capillary liquid bridge is broken, the liquid bridge structure breaks, and the volatile substances originally bound to the surface of soil particles by surface tension are released from the solid-liquid interface, changing from a bound state to a free state, and are released into the gas phase of the micro-pores.

[0074] S123. Intermittent sound pressure pulse control and batch-wise gradual release, specifically:

[0075] The control unit manages the timing of the acoustic pressure pulses, setting the duration of a single pulse to 1 to 5 seconds. This duration is sufficient to complete a full cycle of cavitation bubble growth and collapse, allowing the microjets and shock waves to fully act on the capillary liquid bridges in the current liquid film enrichment zone. After each pulse, a pulse interval of 2 to 10 seconds is set, during which acoustic pressure emission ceases. This allows the microporous liquid film to undergo local thermal diffusion and pressure equilibrium under the continuous action of the photothermal gradient, while simultaneously allowing the volatile substances released in the previous stage to fully diffuse into the gas phase, avoiding fatigue damage to the soil structure caused by continuous ultrasound.

[0076] During the pulse interval, the control unit synchronously acquires the characteristic absorption spectrum of modulated near-infrared light and monitors the gas phase enrichment level in real time. When the monitoring results indicate that the release of the current batch is approaching saturation, the control unit triggers the next cycle of sound pressure pulse, so that the cavitation effect is repeatedly applied to the same micro-region in an intermittent manner. This intermittent control strategy realizes the batch-by-batch, gradual release of bound volatile substances, ensuring that each batch reaches the effective desorption depth while maintaining the structural integrity of the soil micro-region matrix and avoiding pore collapse caused by excessive cavitation.

[0077] S13. Characteristic absorption spectral monitoring and saturation enrichment determination, specifically:

[0078] S131. Background reference value calibration and reference baseline setting, specifically:

[0079] Before formally projecting modulated near-infrared light and coupled acoustic pressure pulses into the soil micro-region, the near-infrared spectral detection unit is first activated to calibrate the background reference value. The detection unit consists of a near-infrared light source, a collimating lens, a narrow-band filter, a photodetector, and a current and voltage amplification circuit. At this time, the modulated near-infrared light passes through the gas phase of the soil micro-region in a low-power detection mode, the acoustic pressure pulse is in the off state, and the micro-region is in a state of natural thermal equilibrium and gas phase equilibrium.

[0080] The photodetector converts the received light signal into a current signal, which is then converted into a voltage signal by an amplification circuit and transmitted to the control unit. The control unit uses the intensity of the characteristic absorption spectrum collected in this state as the background reference value and stores it in a non-volatile memory register. To ensure the stability and reliability of the reference value, the arithmetic mean of 3 to 5 consecutive acquisitions is taken as the final background reference value. The change rate of the characteristic absorption spectrum attenuation is set as a reference baseline with this background reference value as zero. All subsequent attenuation calculations are performed relative to this reference value, thereby eliminating the interference of soil background gas phase absorption and ambient light fluctuations on the judgment results.

[0081] S132. Real-time spectral acquisition and attenuation calculation, specifically:

[0082] During the synergistic effect of the acoustic pressure pulse and the modulated near-infrared light, the near-infrared spectral detection unit switches to a high-speed continuous acquisition mode, continuously acquiring the real-time characteristic absorption spectral intensity of the modulated near-infrared light as it passes through the micro-region gas phase at a fixed sampling interval. The sampling interval is set from 100ms to 500ms by the analog-to-digital converter clock of the control unit.

[0083] After each sampling, the control unit reads the current real-time characteristic absorption spectral intensity, retrieves the stored background reference value, performs real-time difference calculation, and calculates the attenuation amount relative to the background reference value at each sampling time. This attenuation amount equals the background reference value minus the real-time characteristic absorption spectral intensity, and its physical meaning represents the additional light absorption increment caused by the increased concentration of volatile substances in the micro-region gas phase due to photothermal acoustic pressure-coordinated desorption. As the desorption process continues, volatile substances are continuously released into the gas phase, the real-time characteristic absorption spectral intensity gradually decreases, and the attenuation amount increases accordingly. The control unit stores the attenuation amount at each sampling time in a buffer queue according to the time series, providing a data basis for subsequent rate of change extraction.

[0084] S133. Linear fitting and rate of change extraction within a time window, specifically:

[0085] To extract a stable and reliable growth trend criterion from the decay time series, the control unit sets a preset time window of 5 to 30 seconds. Decay data from multiple consecutive sampling moments within this time window are extracted from the buffer queue to form a decay time series. This time series is then linearly fitted, and the slope of the fitted line is calculated using the least squares method. This slope represents the rate of change of decay over time, quantitatively reflecting the net increase rate of volatile substance concentration in the micro-region gas phase within a specific time window.

[0086] In the initial stage of desorption, a large amount of bound material is released, and the decay time series shows a significant upward trend with a large and positive rate of change. As the amount of desorbable material gradually decreases, the newly released amount declines, the decay time series flattens out, and the rate of change decreases and approaches zero. Extracting the rate of change through linear fitting can effectively smooth out the random noise introduced by a single sampling and avoid misjudgments caused by instantaneous fluctuations.

[0087] S134. Saturation enrichment determination and enrichment completion signal generation, specifically:

[0088] The control unit compares the rate of change of the attenuation extracted by S133 over time with a preset threshold in real time. The preset threshold is set based on the initial rate of change obtained by fitting within the first preset time window after desorption begins, and 5% to 15% of the initial rate of change is taken as the judgment threshold.

[0089] When the rate of change of attenuation over time is lower than the preset threshold, it indicates that within the most recent preset time window, the net increase rate of volatile substance concentration in the micro-region gas phase has dropped to an extremely low level. The amount of newly generated gas phase substances from photothermal-acoustic-pressure synergistic desorption and the amount of substances migrating and diffusing away tend to reach a dynamic equilibrium, and the micro-region gas phase has reached a saturated enrichment state. At this time, the control unit immediately generates an enrichment completion signal, which is output in the form of a digital level transition or a standard communication protocol command and transmitted to the directional migration capture module as an enable trigger signal to initiate the vapor pressure gradient construction and thermophoretic directional migration operation based on the saturated enrichment state of the micro-region gas phase.

[0090] Example 3, preferably, in Example 1, step S2 is specifically implemented through the following steps:

[0091] S21. Laser array startup and non-uniform optical field construction, specifically:

[0092] Upon receiving the enrichment completion signal, which characterizes the gas-phase saturation enrichment state of the micro-region, the control unit immediately sends a start command to the laser array deployed above the micro-region. This laser array consists of 3 to 5 semiconductor lasers with independently adjustable output power. Each laser is arranged in a fan shape along the central axis of the micro-region towards the cold end acquisition port, with the angle between adjacent lasers set to 15° to 30° to ensure that the light field coverage area extends from above the micro-region to the cold end acquisition port entrance. Each laser is equipped with an independent constant current drive power supply and a power feedback sensor. The control unit performs real-time closed-loop adjustment of the output power of each laser through a digital-to-analog conversion interface.

[0093] The control unit allocates the output power of each laser differently based on the intensity level of the enriched signal: the lasers near the center of the micro-area have higher output power, set to 60mW to 200mW; the lasers at the edge and near the cold end acquisition port have lower output power, set to 10mW to 40mW; this power gradient configuration creates a non-uniform light field above the micro-area that is strong at the center, weak at the edges, and points towards the cold end acquisition port.

[0094] The wavelength of the non-uniform light field is selected within the range of 600nm to 1000nm based on the characteristic absorption band of the target volatile substance to ensure maximum photothermal conversion efficiency of gas phase molecules. This non-uniform light field selectively photothermally heats the volatile substances in the micro-region gas phase, enabling gas phase molecules to acquire directional kinetic energy within the light field coverage area. As the light field intensity gradually weakens along the direction pointing towards the cold end collection port, a saturated vapor pressure difference is generated between the high-temperature and low-temperature regions of the micro-region gas phase, establishing a local vapor pressure gradient from the micro-region towards the cold end collection port. This local vapor pressure gradient serves as the initial driving force for gas phase migration, propelling the enriched gas phase away from the micro-region and towards the cold end collection port, providing a pressure basis for subsequent thermophoretic force-co-migration.

[0095] S22. Peltier element activation and directional temperature gradient construction, specifically:

[0096] Simultaneously with the laser array activation, the control unit activates Peltier elements embedded in the sidewall of the directional migration channel. These Peltier elements, composed of a thermocouple array and heat sink fins, are arranged at equal intervals along the entire length of the directional migration channel, with the spacing between adjacent elements set to 20mm to 50mm. The cold end of each Peltier element faces the inner wall of the directional migration channel, while the hot end is attached to an external aluminum heat sink substrate. Forced air cooling or liquid cooling is configured on the outside of the substrate. The control unit applies a DC operating current to the Peltier elements via a solid-state relay, with the current direction from the cold end to the hot end, causing the Peltier elements to enter active thermoelectric cooling mode.

[0097] When the Peltier element is energized, a Peltier effect is generated between the cold and hot ends. The cold end absorbs heat from the inner wall of the directional migration channel, while the hot end releases heat to the external heat dissipation substrate. By adjusting the input current of the Peltier element, its cooling power can be controlled to vary within the range of 10W to 50W. This maintains the inner wall temperature near the micro-area at the inlet of the directional migration channel at 25°C to 35°C, and the inner wall temperature near the cold end collection port at the outlet at 0°C to 15°C, thus forming a directional temperature gradient with a temperature difference of 10°C to 30°C between the inlet and outlet. This temperature gradient monotonically decreases along the channel from the micro-area towards the cold end collection port and is kept stable through closed-loop feedback from a temperature sensor.

[0098] In this directional temperature gradient field, volatile molecules in the enriched gas phase are subjected to thermophoretic force, which is the physical effect of molecules migrating from high-temperature regions to low-temperature regions in the temperature gradient field. Since the temperature at the inlet end of the channel is higher than that at the outlet end, the direction of the thermophoretic migration force naturally points towards the cold end collection port. This thermophoretic migration force, together with the pressure driving force generated by the local vapor pressure gradient in S21, constitutes the directional migration driving force of the enriched gas phase, enabling the gas phase to move stably towards the cold end collection port under the combined action of the two forces.

[0099] S23. Dual-force synergistic drive and hydrophobic channel directional transport, specifically:

[0100] The enriched gas phase acquires a composite directional driving force under the synergistic effect of a local vapor pressure gradient and thermophoretic migration force. The local vapor pressure gradient is established by a non-uniform light field between the high-temperature region of the micro-area and the low-temperature region of the cold-end acquisition port, forming a pressure drop from the micro-area to the cold end. The thermophoretic migration force is induced by the directional temperature gradient, causing gas phase molecules to migrate from the high-temperature region to the low-temperature region. Both forces point towards the cold-end acquisition port, forming a superimposed driving effect within the directional migration channel, ensuring that the enriched gas phase has stable directional migration kinetic energy and avoiding migration lag caused by insufficient single driving force.

[0101] The inner wall of the directional migration channel is uniformly coated with a hydrophobic fluorocarbon coating using chemical vapor deposition or plasma spraying. This coating is composed of low surface energy materials such as perfluoropolyether or polytetrafluoroethylene, with a surface contact angle greater than 120°, exhibiting superhydrophobic properties. The coating thickness is controlled within the range of 2μm to 10μm, which can effectively inhibit the adsorption, spreading, and condensation of water vapor and polar impurities in the gas phase on the wall surface, significantly reducing the non-specific retention and surface loss of volatile substances on the inner wall of the channel, and maintaining the relative abundance of target volatile substances in the gas phase.

[0102] The cross-sectional dimensions of the directional migration channel gradually narrow along the migration direction, forming a Venturi tube structure. The inlet diameter is 20mm to 40mm, while the outlet diameter narrows to 10mm to 20mm. This structure maintains the enriched gas phase in a laminar flow state during migration, keeping the Reynolds number below 2300 and avoiding backmixing and diffusion losses caused by turbulence. Under the combined drive of two forces, the enriched gas phase is directionally transported along the inner wall of the channel to the cold-end collection port at a stable flow velocity of 5cm / s to 20cm / s, achieving efficient and lossless migration from the micro-area to the capture end.

[0103] S24. Gradient condensation trapping using a multi-level condensation trap of gold nanorod micropillar arrays, specifically:

[0104] S241. Multi-stage condenser configuration and temperature gradient setting, specifically:

[0105] Multiple condensation traps are deployed at the cold end collection port, and are set as the first and second stages in sequence along the migration direction. Each condensation trap adopts a stainless steel or copper cavity structure, with a semiconductor cooling chip embedded independently at the bottom. The cooling power is adjusted by the control unit, and the temperature is controlled in a closed loop by the wall temperature sensor in real time.

[0106] The first-stage condenser is located near the inlet. The control unit sets its inner wall temperature to 5°C to 15°C. This temperature range is higher than the condensation point of high-boiling-range volatile substances but lower than the condensation point of low-boiling-range substances. It is used to preferentially condense and capture high-boiling-range volatile substances with boiling points above 150°C. The second-stage condenser is located downstream of the first stage. The control unit sets its inner wall temperature to -10°C to 0°C. It is used to condense and capture low-boiling-range volatile substances with boiling points below 150°C.

[0107] Each level of the condenser trap has its inner wall coated with a photothermal responsive micro / nano structure array, which includes, but is not limited to, gold nanorod-modified micropillar arrays, vanadium dioxide phase-change nanopillar arrays, and polydopamine-coated mesoporous silica nanopore arrays, among which:

[0108] The gold nanorod modified micropillar array consists of titanium dioxide micropillars grown vertically on the substrate surface and gold nanorods deposited on the surface via a seed growth method. It serves as a photothermal responsive micro / nanostructure to enhance selective adsorption. Through independent temperature control at each level and synergy with the micro / nanostructure, it achieves gradient condensation separation and capture of volatile substances with different boiling ranges.

[0109] Vanadium dioxide phase-change nanopillar arrays are produced by magnetron sputtering of vanadium dioxide films with a thickness of 200 nm to 500 nm on the surface of a substrate within a condensation trap. The films are then patterned into nanopillar arrays with diameters of 100 nm to 300 nm and heights of 500 nm to 800 nm using reactive ion etching or electron beam lithography. Vanadium dioxide is a monoclinic insulating phase at room temperature and exhibits weak near-infrared absorption. When the photothermal excitation power raises the surface temperature of the micro / nanostructure to near the phase-change threshold of 68 °C, vanadium dioxide undergoes a metal-insulator phase transition, transforming into a tetragonal metallic phase. This results in a sharp increase in near-infrared absorptivity and a rapid rise in surface temperature. This phase transition process is reversible and responsive, enabling temperature-dependent selective adsorption of volatile substances with different boiling ranges on the nanopillar surface. High-boiling-range substances are condensed and anchored at lower temperatures before the phase transition, while low-boiling-range substances require higher temperatures after the phase transition for effective adsorption, thus achieving selective condensation separation in synergy with temperature gradients.

[0110] Polydopamine-coated mesoporous silica nanopore arrays are formed on anodic aluminum oxide templates or silicon substrates through electrochemical etching, resulting in nanopore arrays with pore sizes of 50 nm to 150 nm and pore depths of 300 nm to 600 nm. A mesoporous silica layer is deposited on the pore walls using a sol-gel method, and then a polydopamine film with a thickness of 10 nm to 30 nm is coated onto the inner surface of the pores via dopamine self-polymerization. Polydopamine possesses broad-spectrum absorption characteristics and efficiently converts light energy into heat energy under photothermal excitation. Through the high specific surface area and pore confinement effect of mesoporous silica, a synergistic effect of size sieving and photothermal desorption is achieved for volatile substances of different molecular sizes: large molecules with high boiling ranges preferentially condense at the pore openings, while small molecules with low boiling ranges condense under a stronger photothermal field after penetrating deeper into the pores, achieving gradient-selective capture.

[0111] S242. Vapor phase gradient condensation and selective adsorption condensation, specifically:

[0112] The transported gas phase flows sequentially through the first and second stage condensation traps. When the gas phase enters the first stage condensation trap, due to the high temperature of the trap wall, high-boiling-range volatile substances first liquefy upon cooling on the surface of the photothermal responsive micro / nano structure array, forming a liquid film that is anchored by the capillary force between the micropillars. Under the residual light field or external auxiliary illumination, the gold nanorods generate a localized surface plasmon resonance photothermal effect, making the surface temperature of the micropillars slightly higher than the ambient temperature, forming a dynamic balance between photothermal evaporation and condensation, and inhibiting the co-condensation of non-target substances.

[0113] Low-boiling-range volatile substances remain in a gaseous state in the first stage and continue to migrate to the second stage. Upon entering the second stage, due to the lower trap wall temperature, the low-boiling-range substances condense and are captured on the surface of the photothermal-responsive micro / nanostructure array. The uncondensed residual gas in the two-stage condensation traps is discharged to the waste gas treatment unit through an exhaust pipe connected to the end. High-purity gradient separation and capture of volatile substances with different boiling ranges are achieved through the difference in selective adsorption and condensation behavior between the graded temperature field and the photothermal-responsive micro / nanostructure surface.

[0114] S243. Determination of completion of exhaust port spectral monitoring and capture, specifically:

[0115] Near-infrared spectral detection units are installed at the outlet and inlet of the two-stage condenser traps to monitor the characteristic spectral intensity of the outlet in real time. These detection units share the same wavelength setting and calibration reference as the initial spectral detection unit at the inlet. The control unit uses the initial signal intensity at the inlet as a reference and continuously compares it with the real-time signal intensity at the outlet. When the characteristic spectral intensity at the outlet is continuously lower than 20% of the initial signal intensity at the inlet for one minute, it indicates that the concentration of the target volatile substance in the gas phase flowing through the condenser trap has been significantly reduced, and more than 80% of the target substance has been effectively condensed and captured. At this point, it is determined that the target boiling range substance has been essentially captured. The control unit then generates a capture completion signal, which is transmitted to the subsequent processing unit in the form of a digital level transition, triggering the collection and sealing operation of the staged captured substance and simultaneously starting the next acquisition cycle or the equipment standby program.

[0116] Example 4, preferably, in Example 1, step S3 is specifically implemented through the following steps:

[0117] S31. Broadband detector beam projection and fluorescence excitation-emission matrix spectral acquisition, specifically:

[0118] A broadband probe beam is projected onto the fractionated material. This beam, using a xenon or halogen tungsten lamp as a continuous light source, is dispersed by a grating monochromator to generate tunable excitation light with wavelengths ranging from 200 nm to 600 nm. The beam is then focused and uniformly projected onto a quartz cuvette or open sample cell containing the fractionated material via an fiber optic coupler and collimating lens assembly. This ensures the excitation spot completely covers the effective sample area, avoiding spectral distortion caused by insufficient edge excitation.

[0119] The control unit drives the grating monochromator to scan with excitation steps ranging from 5 nm to 10 nm. Each time an excitation wavelength is switched, the monochromator stably outputs light of that wavelength and continuously irradiates the graded captured material for 1-3 seconds. This causes the molecules to absorb excitation photons, resulting in electrons transitioning from the ground state to the excited state. Subsequently, they release fluorescent photons through radiative transitions. Signal acquisition is only performed after the fluorescence emission reaches a steady state. The entire scan covers the excitation band from 200 nm to 600 nm, forming a discrete sequence of excitation wavelengths, enabling a systematic traversal of the full-band excitation response of the graded captured material.

[0120] A high-sensitivity photomultiplier tube or charge-coupled device array detector is arranged perpendicular to the incident direction of the excitation light. Fluorescence emission signals within the emission wavelength range of 300 nm to 700 nm are collected by dispersion using filters or a second-order monochromator. For each excitation wavelength, the effective emission signal is collected from the emission band greater than that excitation wavelength. The control unit arranges the one-dimensional emission spectra measured at each excitation wavelength in order of excitation wavelength to construct a fluorescence excitation-emission matrix spectrum. This matrix uses the excitation wavelength as the row coordinate and the emission wavelength as the column coordinate, with the matrix elements representing the fluorescence intensity values ​​under the corresponding excitation and emission wavelength combinations, forming a three-dimensional fingerprint spectrum characterizing the fluorescence properties of the hierarchically captured molecules.

[0121] S32. Standard fluorescent fingerprint feature library comparison and deviation calculation, specifically as follows:

[0122] S321. Standard characteristic peak parameter retrieval and extraction, specifically:

[0123] The control unit retrieves the standard excitation-emission matrix corresponding to the current target volatile substance from a pre-stored standard fluorescent fingerprint feature library. The process of establishing this standard fluorescent fingerprint feature library is as follows:

[0124] In a laboratory setting, pure samples of the target volatile substances were used as standard samples for library construction. Dichloromethane or methanol was used as solvents to dissolve the pure substances and prepare a concentration gradient series. This concentration gradient covered the expected concentration range in actual soil sampling scenarios, with the lowest concentration not lower than the fluorescence detection limit and the highest concentration not exceeding the fluorescence quenching threshold. A broadband scan was performed using a standard fluorescence spectrometer equipped with a continuous xenon lamp source, an excitation-side grating monochromator, an emission-side grating monochromator, and a high-sensitivity photomultiplier tube detector. Before scanning, the instrument underwent wavelength and intensity calibration. The accuracy of the excitation and emission wavelengths was corrected using the characteristic spectral lines of the mercury lamp, and the linearity of the fluorescence intensity response was corrected using a standard reference.

[0125] Set the scanning conditions: the excitation wavelength scanning range is 200nm to 600nm, and the excitation step size is 5nm to 10nm; the emission wavelength scanning range is 300nm to 700nm, and the emission step size is 1nm to 2nm; the emission scan integration time for each excitation wavelength is 0.1s to 0.5s; the excitation and emission slit widths are both set to 5nm to 10nm to balance spectral resolution and signal intensity.

[0126] For each concentration gradient, standard samples were sequentially subjected to full-band three-dimensional excitation-emission matrix scanning to acquire raw fluorescence excitation-emission matrix spectra. The raw matrices underwent data preprocessing: first, the solvent blank background matrix was subtracted to eliminate solvent background fluorescence and scattering interference; then, Rayleigh and Raman scattering bands were removed, as these bands are located in regions where the excitation wavelength equals the emission wavelength and the emission wavelength is an integer multiple of the excitation wavelength; next, internal filtering effect correction was performed to eliminate intensity distortion caused by excessive absorption of excitation light in high-concentration samples; finally, the matrix was normalized to scale the global maximum fluorescence intensity value to 1, forming a normalized excitation-emission matrix.

[0127] Characteristic peaks were extracted from the normalized excitation-emission matrix. A peak detection algorithm was used to identify local maxima where the fluorescence intensity was significantly higher than the background noise level. The excitation wavelength, emission wavelength, half-width at half-maximum (FWHM), peak intensity, and peak area of ​​each characteristic peak were recorded. For stable characteristic peaks that repeatedly appeared under different concentration gradients for the same target substance, their average excitation wavelength, average emission wavelength, average peak intensity, and standard deviation were calculated. Characteristic peaks with a standard deviation less than a preset precision were selected as standard characteristic peaks.

[0128] The normalized excitation-emission matrix after the above processing is named the standard excitation-emission matrix. This matrix forms a two-dimensional data table structure with excitation wavelength as the row index, emission wavelength as the column index, and normalized fluorescence intensity as the matrix elements. The above data is encapsulated into standard fluorescence fingerprint feature library entries. Each entry includes: substance identification code, the standard excitation-emission matrix, a list of standard characteristic peaks, and a normalized standard fingerprint spectrum. The standard excitation-emission matrix serves as the core comparison benchmark for subsequent global comparison with the measured fluorescence excitation-emission matrix spectrum. The list of standard characteristic peaks records the excitation wavelength, emission wavelength, standard peak intensity, and half-peak width for each standard characteristic peak, used for local feature comparison and deviation calculation. At least three independent repeated scans are performed on the same pure sample for verification. The characteristic peak position deviation is required to be less than 1 nm, and the relative peak intensity deviation is required to be less than 5%. Only entries that meet this repeatability accuracy requirement can be stored in the standard fluorescence fingerprint feature library.

[0129] During retrieval, the control unit retrieves and reads the corresponding standard excitation-emission matrix based on the target volatile substance identifier set in the current acquisition task. Subsequently, the control unit performs peak analysis on the matrix, identifies local maxima with fluorescence intensity significantly higher than the background noise level as standard characteristic peaks, and accurately extracts the excitation wavelength, emission wavelength, and standard peak intensity corresponding to each standard characteristic peak. These extracted standard parameters serve as the benchmark values ​​for subsequent comparison calculations, used to quantitatively evaluate the consistency between the measured graded captured substances and the standard pure products.

[0130] S322. Preprocessing of measured spectra and identification of characteristic peaks, specifically:

[0131] After receiving the measured fluorescence excitation-emission matrix spectrum from the photodetector, the control unit first performs background removal processing. The control unit calls the pre-acquired blank solvent background matrix, which is measured within the same excitation and emission wavelength range and contains information on solvent background fluorescence and scattered light interference. The corresponding background value is subtracted point by point from the measured fluorescence excitation-emission matrix spectrum to eliminate stray signals from sources other than the sample.

[0132] After background removal, the control unit normalizes the matrix, scaling all fluorescence intensity values ​​to a uniform range of 0-1 to eliminate baseline drift caused by sample concentration differences or instrument response fluctuations. In the background-removed and normalized matrix, the control unit uses a peak detection algorithm to identify measured characteristic peaks, specifically finding local maxima where fluorescence intensity is significantly higher than neighboring regions. The excitation wavelength, emission wavelength, and peak intensity of each measured characteristic peak are recorded, forming a list of measured peak parameters for subsequent comparison.

[0133] S323. Calculation of characteristic peak deviation and quantification of purity, specifically:

[0134] The control unit matches and compares each measured characteristic peak in the measured peak parameter list with the standard characteristic peak. For each successfully matched pair of characteristic peaks, it calculates the excitation wavelength deviation and the emission wavelength deviation, where the excitation wavelength deviation is the measured excitation wavelength minus the standard excitation wavelength, and the emission wavelength deviation is the measured emission wavelength minus the standard emission wavelength. At the same time, it calculates the relative peak intensity deviation, using the standard peak intensity as the denominator, subtracting the standard peak intensity from the measured peak intensity, and then dividing the difference by the standard peak intensity. The resulting ratio is expressed as a percentage.

[0135] If a non-standard fingerprint peak not recorded in the standard fluorescence fingerprint feature library appears in the measured fluorescence excitation-emission matrix spectrum, the control unit marks it as an abnormal peak and records its peak position information. Based on the above wavelength deviation, relative intensity deviation and abnormal peak identification results, the control unit comprehensively quantifies and classifies the degree of deviation of the captured substance from the standard pure product in terms of molecular structure characteristics and concentration level, and provides a basis for generating the first correction signal or the second correction signal.

[0136] S33. Correction signal generation and full-chain closed-loop feedback, specifically:

[0137] S331. First correction signal generation and parameter increment calculation, specifically:

[0138] When the absolute value of the wavelength deviation in the comparison result is greater than 2nm or the relative value of the intensity deviation is greater than 10%, the control unit determines that the synergistic effect of photothermal desorption and acoustic pressure cavitation in S1 is insufficient, resulting in incomplete desorption or photothermal degradation of the material. At this time, the control unit generates a first correction signal, which includes two components: power increment ΔP and acoustic pressure increment ΔS.

[0139] The power increment ΔP is calculated proportionally to the absolute value of the wavelength deviation. A larger absolute value of the wavelength deviation indicates poorer selective excitation of the target functional groups by the modulated near-infrared light, requiring a higher power increment. The control unit sets the power increment to be directly proportional to the absolute value of the wavelength deviation. The power proportionality coefficient is determined by pre-stored calibration parameters, and its value range is 0.1 W / cm². 2 / nm to 1.0W / cm 2 / nm, the classic value is 0.5W / cm 2 / nm.

[0140] The sound pressure increment ΔS is calculated based on the relative intensity deviation using a sound pressure proportionality coefficient. The larger the relative intensity deviation, the less mechanically the sound pressure pulse damages the capillary bridge, and the higher the required sound pressure increment. The control unit sets the sound pressure increment to be proportional to the relative intensity deviation, with the sound pressure proportionality coefficient ranging from 0.005 to 0.05 MPa per percentage point, and the classic value being 0.02 MPa per percentage point.

[0141] The control unit encapsulates the calculated power increment and sound pressure increment into a first correction signal, ready to be transmitted to the S1 adjustment terminal.

[0142] S332. The second correction signal is generated and the condensation power is increased, specifically:

[0143] When a non-standard fingerprint peak not recorded in the standard fluorescent fingerprint feature library appears in the comparison results, the control unit determines that there is non-target material co-condensation or insufficient selective capture in the migration and capture process in S2. At this time, the control unit generates a second correction signal, which contains an instruction to increase the photothermal excitation power of the multi-stage condensation trap:

[0144] The control unit reads the current photothermal excitation power setting value of the multi-stage condensation trap and calculates the adjustment range. The adjustment range is set to 5% to 20% of the current value. The specific ratio is determined based on the number and relative intensity of non-standard fingerprint peaks. The more non-standard fingerprint peaks there are or the higher the relative intensity, the greater the adjustment range, so as to enhance the photothermal evaporation and recondensation balance control capability of the photothermal responsive micro / nano structure surface.

[0145] The control unit encapsulates the photothermal excitation power increase command and the target power value into a second correction signal, ready to be transmitted to the S2 adjustment terminal.

[0146] S333. The first correction signal transmission and desorption parameters increase synchronously, specifically:

[0147] The control unit transmits the first correction signal to the modulation near-infrared light power density adjustment terminal and the sound pressure pulse coupling intensity adjustment terminal, respectively:

[0148] At the modulation near-infrared light power density adjustment end, the control unit increases the input current of the near-infrared light source array through the constant current drive circuit according to the power increment in the first correction signal, so that the modulation near-infrared light power density increases accordingly, thereby enhancing the photothermal gradient in the vertical direction of the micro-area and improving the driving force of layer-by-layer thermal desorption from the surface to the inside.

[0149] At the acoustic pressure pulse coupling intensity adjustment end, the control unit increases the driving voltage of the piezoelectric ceramic transducer through the power amplifier based on the acoustic pressure increment in the first correction signal, thereby increasing the acoustic pressure amplitude of the acoustic pressure pulse accordingly, thereby enhancing the cavitation effect intensity in the pore liquid film and improving the mechanical destruction capability of microjets and shock waves on capillary liquid bridges.

[0150] By simultaneously increasing the photothermal gradient and the intensity of cavitation effect, the desorption efficiency and selectivity of bound volatile substances in S1 are synergistically improved.

[0151] S334. The second correction signal transmission and acquisition capability is enhanced, specifically:

[0152] The control unit transmits the second correction signal to the non-uniform light field intensity adjustment end, the thermophoretic temperature gradient adjustment end, and the multi-stage condenser photothermal excitation parameter adjustment end:

[0153] At the non-uniform light field intensity adjustment end, the control unit increases the output power of each semiconductor laser through the laser array drive circuit according to the photothermal excitation power increase instruction in the second correction signal, thereby increasing the intensity of the non-uniform light field accordingly, thereby strengthening the local vapor pressure gradient from the micro-area to the cold end collection port, enhancing the directivity of the light field, and suppressing the migration of non-target substances with the gas phase.

[0154] At the thermophoretic temperature gradient adjustment end, the control unit synchronously increases the input current of the Peltier element, thereby increasing the temperature difference of the directional temperature gradient, which enhances the thermophoretic migration force and improves the directional transport efficiency of the enriched gas phase towards the cold end collection port. Simultaneously, after the photothermal excitation power of the multi-stage condensation trap is increased, the surface photothermal effect of the photothermal responsive micro / nano structure array is enhanced, the selective adsorption and condensation capacity is improved, and the co-condensed substances corresponding to non-standard fingerprint peaks are effectively suppressed.

[0155] The control unit repeatedly executes operations S1 to S3 until the comparison deviation meets the preset threshold, forming a closed-loop acquisition chain. The preset thresholds include wavelength deviation preset threshold, intensity relative deviation preset threshold, and non-standard fingerprint peak preset threshold. The wavelength deviation preset threshold ranges from 0.5nm to 2nm, with a classic value of 2nm. The intensity relative deviation preset threshold ranges from 5% to 10%, with a classic value of 10%. The non-standard fingerprint peak preset threshold ranges from 0% to 5%. The classic value is 0%, meaning the non-standard fingerprint peak relative intensity is the percentage of the main feature peak intensity.

[0156] Example 5, as Figure 2 As shown, a soil volatile matter collection system is used to implement a soil volatile matter collection method, comprising:

[0157] The photothermal acoustic pressure synergistic desorption module is used to project modulated near-infrared light into soil micro-regions, coupled with acoustic pressure pulses to induce cavitation effect of pore liquid film, destroy capillary liquid bridge binding, and cause volatile substances to be synergistically desorbed from the solid-liquid interface and enriched in the micro-region pore gas phase. Modulated near-infrared light is used as the detection light to collect the characteristic absorption spectrum intensity attenuation when it passes through the micro-region gas phase, and to determine the saturation enrichment state of the micro-region gas phase.

[0158] The directional migration selective capture module is used to construct a non-uniform light field and a directional temperature gradient to form a vapor pressure gradient and thermophoretic effect based on the saturated enrichment state of the gas phase in a micro-region. Under the synergistic effect of the vapor pressure gradient and thermophoretic force, the enriched gas phase migrates along the directional migration channel to the cold end collection port. A multi-level condensation trap covered with a photothermal responsive micro-nano structure array is set at the cold end collection port to achieve gradient condensation capture and obtain graded captured substances.

[0159] The fluorescence verification closed-loop correction module is used to project a broadband detection beam onto the graded captured material, collect the characteristic fluorescence excitation-emission matrix spectrum, compare it with the standard fluorescence fingerprint feature library to verify optical purity, generate a correction signal based on the purity comparison deviation, and feed back to adjust the modulated near-infrared light power density and acoustic pressure pulse coupling strength of the photothermal acoustic pressure co-desorption module. At the same time, it adjusts the non-uniform light field intensity, thermophoresis temperature gradient, and photothermal excitation parameters of the directional migration selective capture module, forming a complete closed-loop acquisition chain.

[0160] In some embodiments, the soil volatile matter collection system of the present invention can be implemented by a combination of hardware and software. As an example, the soil volatile matter collection system of the present invention can be a processor in the form of a hardware decoding processor, which is programmed to execute the soil volatile matter collection method of the present invention. For example, the processor in the form of a hardware decoding processor can be one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic components.

[0161] The modules described in the embodiments of the present invention can be implemented in software or hardware. The names of the modules are not, in some cases, intended to limit the functionality of the module itself.

[0162] An electronic device according to an embodiment of the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements any of the above-mentioned methods for collecting volatile substances in soil. That is, an electronic device according to an embodiment of the present invention may include, but is not limited to: a processor and a memory; the memory is used to store the computer program; the processor is used to execute a method for collecting volatile substances in soil according to any embodiment of the present invention by calling the computer program.

[0163] In one alternative embodiment, an electronic device is provided, such as Figure 3 As shown, Figure 3The illustrated electronic device 4000 includes a processor 4001 and a memory 4003. The processor 4001 and the memory 4003 are connected, for example, via a bus 4002. Optionally, the electronic device 4000 may further include a transceiver 4004, which can be used for data interaction between the electronic device and other electronic devices, such as sending and / or receiving data. It should be noted that in practical applications, the transceiver 4004 is not limited to one type, and the structure of the electronic device 4000 does not constitute a limitation on the embodiments of the present invention.

[0164] Processor 4001 may be a CPU (Central Processing Unit), a general-purpose processor, a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute the various exemplary logic blocks, modules, and circuits described in conjunction with the disclosure of this invention. Processor 4001 may also be a combination that implements computational functions, such as including one or more microprocessor combinations, a combination of a DSP and a microprocessor, etc.

[0165] Bus 4002 may include a path for transmitting information between the aforementioned components. Bus 4002 may be a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. Bus 4002 can be divided into address bus, data bus, control bus, etc. For ease of representation, Figure 3 The bus 4002 is represented by only one thick line, but this does not mean that there is only one bus or one type of bus.

[0166] The memory 4003 may be ROM (Read Only Memory) or other types of static storage devices capable of storing static information and instructions, RAM (Random Access Memory) or other types of dynamic storage devices capable of storing information and instructions, or EEPROM (Electrically Erasable Programmable Read Only Memory), CD-ROM (Compact Disc Read Only Memory) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto.

[0167] The memory 4003 stores application code (computer program) for executing the present invention, and its execution is controlled by the processor 4001. The processor 4001 executes the application code stored in the memory 4003 to implement the content shown in the foregoing method embodiments.

[0168] Among them, electronic devices can also be terminal devices, which can be any device that can install applications, including at least one of smartphones, tablets, laptops, desktop computers, smart speakers, smartwatches, smart TVs, and smart in-vehicle devices.

[0169] It should be noted that, Figure 3 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0170] An embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements any one of the above-described methods for collecting volatile substances in soil.

[0171] Alternatively, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), magnetic tape, a floppy disk, and an optical data storage device, etc.

[0172] In an exemplary embodiment, a computer program product or computer program is also provided, which includes computer instructions stored in a computer-readable storage medium. The processor of an electronic device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the electronic device to perform the aforementioned method and system for collecting volatile substances in soil.

[0173] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof. These programming languages ​​include object-oriented programming languages—such as Java, Smalltalk, and C++—and conventional procedural programming languages—such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0174] It should be understood that the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation that may be implemented in the methods and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0175] The computer-readable storage medium provided in this invention can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EEPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0176] The aforementioned computer-readable storage medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the method shown in the above embodiments.

[0177] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-disclosed concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0178] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and represent a limitation on a specific order or sequence. Where appropriate, the order of use for similar objects can be interchanged so that the embodiments of this application described herein can be implemented in an order other than that shown or described.

[0179] Those skilled in the art will recognize that this invention can be implemented as a system, method, or computer program product. Therefore, this invention can be specifically implemented in the following forms: it can be entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software, generally referred to herein as a "circuit," "module," or "system." Furthermore, in some embodiments, this invention can also be implemented as a computer program product contained in one or more computer-readable media, which includes computer-readable program code.

[0180] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method of soil volatile collection, comprising: include: Modulated near-infrared light is projected onto soil micro-regions and coupled with acoustic pressure pulses to induce cavitation effect of pore liquid film, thereby destroying capillary liquid bridge binding. Using the modulated near-infrared light as the detection light, the characteristic absorption spectrum intensity attenuation when it passes through the micro-region gas phase is collected to determine the saturated enrichment state of the micro-region gas phase. Based on the gas-phase saturated enrichment state of the micro-region, a non-uniform light field and a directional temperature gradient are constructed to form a vapor pressure gradient and a thermophoretic effect; a multi-stage condensation trap covered with a photothermal responsive micro-nano structure array is set at the cold end collection port to realize gradient condensation capture and obtain graded captured substances. A broadband detection beam is projected onto the graded captured material to collect the characteristic fluorescence excitation-emission matrix spectrum, which is compared with a standard fluorescence fingerprint feature library to verify optical purity. A correction signal is generated based on the purity comparison deviation, and the near-infrared light power density, acoustic pressure pulse coupling strength, non-uniform light field intensity, thermophoretic temperature gradient, and multi-stage condenser photothermal excitation parameters are adjusted and modulated.

2. The method of claim 1, wherein, The process involves projecting modulated near-infrared light into soil micro-regions, coupling it with acoustic pressure pulses to induce cavitation effects in pore liquid films, and disrupting capillary liquid bridge binding. Using the modulated near-infrared light as a probe, the characteristic absorption spectral intensity attenuation as it passes through the gas phase of the micro-region is collected to determine the saturated enrichment state of the gas phase in the micro-region. Specifically, this includes: Near-infrared light is projected onto soil micro-regions to establish a photothermal gradient from the surface to the interior in the vertical direction of the micro-regions; Synchronously couple acoustic pressure pulses to the same micro-region to induce cavitation effect of pore liquid film, causing volatile substances bound by capillary liquid bridges to be released into the gas phase; A background baseline value is set, and the characteristic absorption spectrum attenuation of the modulated near-infrared light passing through the micro-region gas phase is collected in real time. When the rate of change of the attenuation within a preset time window is lower than a preset threshold, it is determined that the micro-region gas phase has reached a saturated enrichment state.

3. The method of claim 2, wherein, The simultaneous coupling of acoustic pressure pulses to the same micro-region induces cavitation in the pore liquid film, causing volatile substances bound by capillary liquid bridges to be released into the gas phase, specifically including: The acoustic pressure pulse is coupled to the projection area of ​​modulated near-infrared light in a phase-synchronized manner, so that the antinode of the acoustic pressure pulse is aligned with the pore liquid film enrichment area of ​​the soil micro-region. Transient cavitation bubbles are induced in the liquid film by sound pressure pulses. The cavitation bubbles generate local micro-jet and shock wave at the moment of collapse, which mechanically destroys the solid-liquid interface adhesion of the capillary liquid bridge. The duration of the sound pressure pulse is controlled to be 1 to 5 seconds, and the pulse interval is 2 to 10 seconds, so that the cavitation effect is repeatedly applied to the same micro-region in an intermittent manner, thereby realizing the batch and gradual release of bound volatile substances.

4. The method of claim 2, wherein the soil volatile is collected by a method comprising: The set background reference value is used to collect the characteristic absorption spectrum attenuation of the modulated near-infrared light as it passes through the micro-region gas phase in real time. When the rate of change of the attenuation within a preset time window is lower than a preset threshold, it is determined that the micro-region gas phase has reached a saturated enrichment state. Specifically, this includes: The characteristic absorption spectrum intensity before the projection of modulated near-infrared light and before the coupling of acoustic pressure pulse is used as the background reference value, and the rate of change of the characteristic absorption spectrum attenuation is set as the reference baseline. During the acoustic pressure pulse, the real-time characteristic absorption spectrum intensity of the modulated near-infrared light passing through the micro-region gas phase is continuously acquired at fixed sampling intervals, and the attenuation amount relative to the background reference value is calculated at each sampling time. Linearly fit the attenuation at multiple consecutive sampling times within a preset time window to obtain the rate of change of attenuation over time. When the rate of change of the attenuation over time is lower than a preset threshold, it is determined that the micro-region gas phase has reached a saturated enrichment state, and an enrichment completion signal is generated.

5. The method of claim 1, wherein the soil volatile is a volatile organic compound. Based on the aforementioned micro-region gas-phase saturated enrichment state, a non-uniform light field and directional temperature gradient are constructed to form a vapor pressure gradient and thermophoretic effect, specifically including: Based on the gas-phase saturated enrichment state of the micro-region, a set of independently controllable laser arrays is activated to generate a non-uniform light field pointing towards the cold end acquisition port above the micro-region, forming a local vapor pressure gradient. The Peltier element set on the side wall of the directional migration channel is activated synchronously to generate a directional temperature gradient with a temperature difference of 10°C to 30°C, which induces the enriched gas phase to generate a thermophoretic migration force towards the cold end. The enriched gas phase is transported directionally to the cold end collection port through a directional migration channel coated with a hydrophobic fluorocarbon coating on the inner wall, under the combined effect of vapor pressure gradient and thermophoretic force.

6. The method of claim 1, wherein, The multi-stage condensation trap, covered with a photothermal-responsive micro / nano structure array, is set at the cold end collection port to achieve gradient condensation capture and obtain graded captured material, specifically including: The multi-stage condenser is set as the first and second stage along the migration direction, and the operating temperature of each condenser decreases step by step along the migration direction to capture volatile substances with different boiling ranges respectively. The transported gas phase flows sequentially through the first and second stages, where volatile substances with different boiling ranges selectively adsorb and condense on the surface of the photothermal responsive micro / nano structure, and the uncondensed gas is discharged through the exhaust pipe. The characteristic spectral intensity of the outlet of the two-stage condenser is monitored in real time. When the signal intensity of the outlet is lower than 20% of the initial signal of the inlet for 1 minute, it is determined that the target boiling range substance has been basically captured, and a capture completion signal is generated.

7. The method of claim 1, wherein the soil volatile is a volatile organic compound. A broadband detection beam is projected onto the graded captured material to collect characteristic fluorescence excitation-emission matrix spectra, which are then compared with a standard fluorescence fingerprint feature library to verify optical purity. A correction signal is generated based on the purity comparison deviation, and feedback is used to adjust the modulation of near-infrared light power density, acoustic pressure pulse coupling strength, non-uniform light field intensity, thermophoretic temperature gradient, and multi-stage condenser photothermal excitation parameters, specifically including: A broadband detection beam with a wavelength of 200 nm to 600 nm is projected onto the graded captured material, and the fluorescence excitation-emission matrix spectrum in the emission wavelength range of 300 nm to 700 nm is collected by scanning with an excitation step size of 5 nm to 10 nm. The measured fluorescence excitation-emission matrix spectrum is compared with the pre-stored standard fluorescence fingerprint feature library to calculate the characteristic peak position deviation and peak intensity relative deviation. When the position deviation of the characteristic peak is greater than 2nm or the relative deviation of the peak intensity is greater than 10%, a first correction signal is generated and fed back to the modulation of near-infrared light power density and acoustic pressure pulse coupling intensity adjustment terminals; when a non-standard fingerprint peak appears in the measured spectrum, a second correction signal is generated and fed back to the non-uniform light field intensity, thermophoretic temperature gradient and multi-stage condenser photothermal excitation parameter adjustment terminals.

8. The method of claim 7, wherein, The measured fluorescence excitation-emission matrix spectrum is compared with a pre-stored standard fluorescence fingerprint feature library. The calculation of characteristic peak position deviation and peak intensity relative deviation includes: Retrieve the standard excitation-emission matrix corresponding to the current target volatile substance from the pre-stored standard fluorescent fingerprint feature library, and extract the excitation wavelength, emission wavelength and standard peak intensity of the standard characteristic peak; After removing background and normalizing the measured fluorescence excitation-emission matrix spectrum, the measured characteristic peaks were identified, and the excitation wavelength, emission wavelength, and peak intensity of the measured characteristic peaks were recorded. Calculate the excitation wavelength deviation, emission wavelength deviation, and relative peak intensity deviation between the measured characteristic peak and the standard characteristic peak. The wavelength deviation is the difference between the measured wavelength and the standard wavelength, and the relative intensity deviation is the percentage of the difference between the measured intensity and the standard intensity relative to the standard intensity.

9. A method for collecting volatile substances in soil according to claim 8, characterized in that, When the characteristic peak position deviation is greater than 2 nm or the peak intensity relative deviation is greater than 10%, a first correction signal is generated and fed back to the modulation near-infrared light power density and acoustic pressure pulse coupling intensity adjustment terminals; when a non-standard fingerprint peak appears in the measured spectrum, a second correction signal is generated and fed back to the non-uniform light field intensity, thermophoretic temperature gradient, and multi-stage condenser photothermal excitation parameter adjustment terminals, specifically including: When the absolute value of the wavelength deviation in the comparison result is greater than 2nm or the relative intensity deviation is greater than 10%, a first correction signal is generated. The first correction signal includes the power increment ΔP and the sound pressure increment ΔS. When a non-standard fingerprint peak appears in the comparison result, a second correction signal is generated. The second correction signal contains an instruction to increase the photothermal excitation power of the multi-stage condenser. The first correction signal is transmitted to the modulation near-infrared light power density adjustment end and the acoustic pressure pulse coupling intensity adjustment end respectively, so as to simultaneously increase the photothermal gradient and cavitation effect intensity. The second correction signal is transmitted to the non-uniform light field intensity adjustment end, the thermophoretic temperature gradient adjustment end, and the multi-stage condenser photothermal excitation parameter adjustment end to enhance the light field directivity and the selective capture capability of the condenser. The operation is repeated until the comparison deviation meets the preset threshold.

10. A soil volatile matter collection system, characterized in that, A method for collecting volatile substances in soil according to any one of claims 1-9 includes: The photothermal acoustic pressure synergistic desorption module is used to project modulated near-infrared light into soil micro-regions, coupled with acoustic pressure pulses to induce cavitation effect of pore liquid film, destroy capillary liquid bridge binding, and cause volatile substances to be synergistically desorbed from the solid-liquid interface and enriched in the micro-region pore gas phase. The modulated near-infrared light is used as the detection light to collect the characteristic absorption spectrum intensity attenuation when it passes through the micro-region gas phase, and to determine the saturated enrichment state of the micro-region gas phase. The directional migration selective capture module is used to construct a non-uniform light field and a directional temperature gradient to form a vapor pressure gradient and thermophoretic effect based on the saturated enrichment state of the gas phase in the micro-region. Under the synergistic effect of the vapor pressure gradient and thermophoretic force, the enriched gas phase migrates along the directional migration channel to the cold end collection port. A multi-level condensation trap covered with a photothermal responsive micro-nano structure array is set at the cold end collection port to realize gradient condensation capture and obtain graded captured substances. The fluorescence verification closed-loop correction module is used to project a broadband detection beam onto the graded captured material, collect the characteristic fluorescence excitation-emission matrix spectrum, compare it with the standard fluorescence fingerprint feature library to verify optical purity, generate a correction signal based on the purity comparison deviation, and feed back to adjust the modulated near-infrared light power density and acoustic pressure pulse coupling strength of the photothermal acoustic pressure co-desorption module. At the same time, it adjusts the non-uniform light field intensity, thermophoresis temperature gradient, and photothermal excitation parameters of the directional migration selective capture module to form a full-chain closed-loop acquisition.

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