In-situ chemical reaction imaging method and application

Abstract

The application discloses an in-situ chemical reaction imaging method and application, comprising the following steps: constructing a diamond-containing chemical reaction-quantum sensing integrated sample pool and corresponding imaging configuration required for reaction; before the reaction starts, a continuous adjustable magnetic field is applied to the diamond, and a certain axis of the diamond NV color center is aligned with the magnetic field; based on a basic pulse sequence, microwave and laser are output to initialize and control the electronic spin state of the diamond NV color center, and the intrinsic property of the diamond is measured; when the reaction starts, the diamond NV color center is excited and controlled according to the measurement pulse sequence corresponding to the physical quantity to be measured in the control strategy, so that the NV color center electron spin evolves with the environment physical field; the fluorescence intensity change of the diamond NV color center is synchronously and dynamically monitored in real time during the reaction process; data processing and image reconstruction are carried out based on the fluorescence intensity change; and the chemical reaction process is monitored and imaged in real time in-situ with the advantages of a large field of view, high sensitivity and high space-time resolution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemistry and chemical imaging, and particularly relates to an in-situ chemical reaction imaging method and application. BACKGROUND

[0002] Real-time monitoring and imaging of chemical reaction processes are of great significance in the fields of chemistry, biology, material science, etc. Traditional chemical imaging techniques, such as fluorescence microscopy and Raman spectroscopy, have certain time-space resolution, but have limitations in sensitivity and chemical specificity. Electron microscopy can achieve high spatial resolution for observing chemical material structures, but it is difficult to realize direct reaction imaging in solution systems. In recent years, quantum sensing technology based on diamond nitrogen vacancy (NV) color centers has gradually become a research hotspot in the cross-field due to its high sensitivity, high time-space resolution and good compatibility with room temperature solution systems.

[0003] Diamond NV color centers are a kind of quantum system with unique optical and magnetic properties, which can realize high-sensitivity multi-physical field measurement at room temperature. From the measurement principle, the electron energy level ground state of NV color centers is a spin triplet state, which can be subjected to Zeeman splitting under an external magnetic field. Through the Optically Detected Magnetic Resonance (ODMR) technology, the energy level structure can be accurately measured. In addition, NV color centers are extremely sensitive to changes in the electric field, magnetic field and temperature of the surrounding environment, so they can be used to detect small physical and chemical changes produced in the chemical reaction process.

[0004] Based on the above characteristics that diamond NV color centers are extremely sensitive to changes in the electric field, magnetic field and temperature of the surrounding environment, diamond NV color centers are used in the prior art for magnetic imaging, such as the patent application with publication number CN116879820A which discloses a high-pressure diamond NV color center-based magnetic imaging device and method; diamond NV color centers are also used for microwave reflection imaging, such as the patent application with publication number CN115791740A which discloses a diamond NV color center-based microwave reflection imaging detection device; diamond NV color centers are also used for temperature imaging, such as the patent application with publication number CN115165139A which discloses a temperature imaging system based on diamond NV color centers for temperature measurement.

[0005] However, the existing in-situ chemical reaction imaging method based on diamond NV color center faces many difficulties, for example: the measurement scene of diamond needs to be compatible with the chemical reaction environment, the background noise that is not needed needs to be suppressed during signal collection, high time resolution, high spatial resolution and high sensitivity are realized to detect the kinetic information of the reaction process, and a reasonable measurement scheme is designed to realize the chemical specificity measurement of NV color center. SUMMARY

[0006] In view of the above, the purpose of the present application is to provide an in-situ chemical reaction imaging method and application. The method utilizes the high sensitivity and high spatial resolution characteristics of diamond NV color center to realize real-time monitoring and imaging of the chemical reaction process in a large field of view.

[0007] To achieve the above-mentioned purpose of the application, an embodiment provides an in-situ chemical reaction imaging method, comprising the following steps:

[0008] A chemical reaction-quantum sensing integrated sample pool containing diamond required for the reaction is constructed and the corresponding imaging configuration is constructed, and a chemical reaction generation module is deployed according to experimental requirements;

[0009] Before the reaction starts, a continuous adjustable magnetic field is applied to the diamond in the chemical reaction-quantum sensing integrated sample pool, and a certain axis of the NV color center of the diamond is aligned with the magnetic field, the microwave and laser based on the basic pulse sequence are output to initialize and control the electronic spin state of the diamond NV color center, and the intrinsic properties of the diamond are measured;

[0010] The reaction is started by using the chemical reaction generation module, and subsequent measurement is carried out, at the beginning of the reaction, the diamond NV color center is excited and controlled according to the measurement pulse sequence corresponding to the physical quantity to be measured contained in the control strategy, so that the NV color center electron spin evolves with the environment physical field, and during the reaction process, the fluorescence intensity change of the diamond NV color center is synchronously and dynamically monitored in-situ in real time, data processing and image reconstruction are carried out based on the fluorescence intensity change, and the in-situ imaging result of the chemical reaction is obtained.

[0011] Preferably, the chemical reaction-quantum sensing integrated sample pool containing diamond required for the reaction is constructed, comprising:

[0012] Firstly, the diamond is pretreated to form a carboxylated surface, and a surface waveguide is prepared on the surface, and a PCB board is connected outside the surface waveguide, the PCB board is used to receive and radiate the microwave signal transmitted from the microwave module, and the microwave is radiated to the NV color center in the diamond at a close distance through the surface waveguide;

[0013] Then, after fixing the sample to be tested on the exposed surface of the diamond substrate, the whole is enclosed in an imaging configuration to form a chemical reaction-quantum sensing integrated sample cell containing the diamond, wherein the imaging configuration includes a solid-liquid interface configuration and a solid-gas interface configuration.

[0014] Preferably, a microwave source is used to output pulsed microwaves controlled by a basic pulse width sequence or a measurement pulse sequence and delivered to the chemical reaction-quantum sensing integrated sample cell containing the diamond through a coaxial phase-stable cable, wherein the microwave source can generate a continuously adjustable microwave signal with a frequency of 0-13 GHz.

[0015] Preferably, a continuously adjustable magnetic field is applied to the diamond by an introduced electromagnet module, wherein the electromagnet module includes a set of five-axis electromagnets that can be used to apply a magnetic field in any direction at the diamond, with a magnetic field strength ranging from [-250, +250] Gauss and a resolution of 1 Gauss, and a programmable DC power supply controlled by the control and processing module, which outputs adjustable DC to regulate the magnetic field strength output by the five-axis electromagnets.

[0016] Preferably, the diamond NV center is excited and the change in fluorescence intensity of the diamond NV center is monitored in real time and in situ by an introduced optical imaging module, wherein the optical imaging module includes a laser system, an acousto-optic modulator, a first optical path, an objective lens, a second optical path, and an imaging device.

[0017] The outgoing laser of the laser system passes through the acousto-optic modulator and is modulated into pulsed laser by the control and processing module, and then passes through the first optical path and the objective lens to irradiate the surface of the diamond in the chemical reaction-quantum sensing integrated sample cell, and the fluorescence signal of the diamond NV center excited by the laser is collected by the objective lens and then detected by the imaging device through the second optical path.

[0018] The laser system also emits excitation light for various chemical reactions to meet different wavelength and power requirements.

[0019] Preferably, the imaging device includes an sCMOS imaging camera and a single-photon detector, in a wide-field imaging configuration, the sCMOS imaging camera is used to collect the fluorescence signal of the diamond NV center, and in the first optical path, there is also a lens that converges the laser entering the objective lens; in a confocal imaging configuration, the single-photon detector is used to collect the fluorescence signal of the diamond NV center.

[0020] Preferably, the in-situ chemical reaction imaging is controlled by a control and processing module, which comprises a workstation, an arbitrary waveform generator, and a processing unit, wherein the workstation is used to send start, stop or other special instructions to the instruments in each module that meet various communication protocols, the arbitrary waveform generator is used to send the measurement pulse sequence in the control strategy to each instrument involved in the sequence for clock synchronization, and the processing unit processes the data and reconstructs the image based on the fluorescence intensity change to obtain the imaging result.

[0021] Preferably, the control strategy comprises:

[0022] The continuous wave optical detection magnetic resonance (CW-ODMR) sequence is used for the measurement of magnetic field and current, the pulsed optical detection magnetic resonance (Pulsed-ODMR) sequence is used for the measurement of temperature, electric field and stress, the longitudinal relaxation (T1 relaxometry) sequence is used for the measurement of free radical and paramagnetic ion concentration, and the double electron-electron resonance (DEER) sequence is used for the analysis of free radical and other species.

[0023] Preferably, the data processing and image reconstruction based on the fluorescence intensity change comprise:

[0024] (a) Signal extraction: extracting the reference fluorescence signal of the diamond NV center from the fluorescence information of the in-situ imaging by the experimental method of signal / reference frame, so as to eliminate the low-frequency noise of the background as much as possible;

[0025] (b) Line fitting: fitting the fluorescence trajectory of each pixel point in the reference fluorescence information to extract the information value contained in the sequence, including: extracting the energy level splitting and zero field splitting value in the CW-ODMR sequence or Pulsed-ODMR sequence by Lorentz line fitting, extracting the relaxation rate value in the T1 relaxometry sequence by relaxation line fitting, and extracting the resonance frequency value in the DEER sequence by multi-Lorentz fitting;

[0026] (c) Chemical reaction parameter calculation: calculating the parameters related to the chemical reaction process according to the information value extracted by the line fitting, including: calculating the magnetism of the chemical reaction product, the current in the electrochemical reaction process by the linear relationship between the energy level splitting value and the size of the external magnetic field, calculating the chemical reaction heat and the stress change occurring in the chemical reaction process by the correlation between the change of the zero field splitting value and the temperature and pressure, calculating the concentration and distribution of paramagnetic ions and free radicals by the quantitative relationship between the relaxation rate value and the intensity of paramagnetic noise, and calculating the species attribution of free radicals and paramagnetic ions by the resonance frequency value;

[0027] (d) Image reconstruction: reconstructing the data obtained by the chemical reaction parameter calculation into two-dimensional or three-dimensional images to display the spatial distribution of the chemical reaction parameters;

[0028] (e) Image denoising: using median filtering, Gaussian filtering, or deep learning methods to denoise the original image reconstructed by the image;

[0029] (f) Dynamic display: displaying the dynamic process of the chemical reaction through the time series image, and capturing the fast reaction event.

[0030] To achieve the above-mentioned purposes, the embodiments of the present application also provide an in-situ chemical reaction imaging application, which uses the in-situ chemical reaction imaging method described above to realize in-situ chemical reaction imaging, including imaging of free radical distribution, ion distribution, chemical reaction rate, chemical reaction product distribution, chemical reaction electric field, chemical reaction current, chemical reaction pressure and stress, and chemical reaction heat, etc.

[0031] Compared with the prior art, the in-situ chemical reaction imaging method provided by the present application has at least the following beneficial effects:

[0032] (1) High sensitivity: the method is based on the imaging means of diamond NV color centers, and has extremely high sensitivity to optical, electrical, magnetic, thermal and other signals involved in the chemical reaction process. For example, the method has strong detection capability for the high-frequency magnetic signal of free radicals, and can detect the concentration of the lowest 5 free radicals per pixel;

[0033] (2) High time-space resolution: based on the wide-field microscopic imaging technology of the optical imaging module in the method, the spatial resolution can reach the level of hundreds of nanometers, which can be used to clearly judge the active sites on the surface of the catalyst; combined with the control and processing module in the method, the time resolution can reach the level of milliseconds, which can quickly capture the changes of physical quantities in the chemical reaction process;

[0034] (3) In-situ and non-destructive: using the method of the present application, the reaction system does not need to be sampled or labeled, and the synchronization of chemical reaction and NV color center quantum sensing can be realized, and the parameter changes of the chemical reaction system can be calculated based on the NV color center imaging results, realizing real in-situ and real-time monitoring;

[0035] (4) Wide applicability: in addition to photocatalytic reactions, the method of the present application can also be applied to chemical reaction imaging research in the fields of electrochemistry and biochemistry. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0037] Figure 1 is a flow chart of the in-situ chemical reaction imaging method provided by the embodiments;

[0038] Figure 2 is a structural schematic diagram of the in-situ chemical reaction imaging device provided by the embodiments;

[0039] Figure 3 is a structural schematic diagram of the chemical reaction-quantum sensing integrated sample cell provided by the embodiments;

[0040] Figure 4 is an imaging configuration of different reaction interfaces provided by the embodiments;

[0041] Figure 5 is a control schematic diagram of the control and processing module provided by the embodiments;

[0042] Figure 6 is a sequence design interface schematic diagram provided by the embodiments;

[0043] Figure 7 is an energy level structure of an NV color center and a corresponding pulse control strategy of multi-modal measurement provided by the embodiments;

[0044] Figure 8 is an in-situ free radical imaging graph of a photocatalytic reaction provided by the embodiments;

[0045] Figure 9 is a free radical spatiotemporal dynamic imaging graph of a photocatalytic reaction provided by the embodiments;

[0046] Figure 10 is an active site transfer mechanism in a catalyst particle in a photocatalytic reaction provided by the embodiments;

[0047] Figure 11 is an in-situ ESR spectrum of a chemical reaction provided by the embodiments;

[0048] Figure 12 is a magnetic imaging graph of a biological mineralization reaction provided by the embodiments;

[0049] Figure 13 is a chemical reaction product distribution graph provided by the embodiments;

[0050] Figure 14 is an in-situ spatiotemporal resolution imaging graph and kinetic measurement of a magnetosome provided by the embodiments;

[0051] Figure 15 is a chemical reaction thermal imaging graph provided by the embodiments. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below with reference to the drawings and examples. It should be understood that the specific implementation described herein is only used to explain the present application and does not limit the protection scope of the present application.

[0053] As shown in Figure 1 The embodiment also provides an in-situ chemical reaction imaging method, comprising the following steps:

[0054] A diamond-containing chemical reaction-quantum sensing integrated sample cell required for constructing a reaction and a corresponding imaging configuration are provided, and a chemical reaction generation module is arranged according to experimental requirements

[0055] Before the reaction starts, a continuous adjustable magnetic field is applied to the diamond in the chemical reaction-quantum sensing integrated sample cell, and a certain axis of the NV center of the diamond is aligned with the magnetic field, microwave and laser are output based on a basic pulse sequence to initialize and control the electronic spin state of the NV center of the diamond, and the intrinsic properties of the diamond are measured;

[0056] The reaction is started by using the chemical reaction generation module, and subsequent measurement is performed, at the start of the reaction, the NV center of the diamond is excited and controlled according to the measurement pulse sequence corresponding to the physical quantity to be measured contained in the control strategy, so that the NV center electronic spin evolves with the environment physical field, and during the reaction process, the fluorescence intensity change of the NV center of the diamond is synchronously and real-timely dynamically monitored in-situ, data processing and image reconstruction are performed based on the fluorescence intensity change, and the in-situ imaging result of the chemical reaction is obtained.

[0057] Through the above steps, real-time monitoring and in-situ imaging of the chemical reaction process are realized, which takes into account the characteristics of a large field of view, high sensitivity, high spatiotemporal resolution and the like. During the reaction process, experimental parameters can also be optimized, the contrast of physical quantity measurement and the time resolution are balanced, and the measurement pulse sequence is adjusted according to the time scale of the chemical reaction, so as to realize in-situ dynamic imaging of the spatiotemporal resolution.

[0058] The embodiment also provides an optional matching device for realizing the above in-situ chemical reaction imaging reaction, as shown in Figure 2 The matching device comprises a chemical reaction generation module, an optical imaging module, a microwave module, an electromagnet module and a control and processing module.

[0059] In the embodiment, the chemical reaction generation module comprises a reaction device supporting various chemical reactions, a chemical reaction-quantum sensing integrated sample cell containing diamond, and a displacement table, wherein the chemical reaction-quantum sensing integrated sample cell cooperates with the reaction device to perform various chemical reactions under the support and precise movement of the displacement table.

[0060] The reaction device includes a temperature control device used in biological and chemical reactions of living cells, a fluid circulation device used in liquid phase reactions, a gas pump device used in gas phase reactions, and an electrochemical workstation used in electrochemical reactions. In application, the corresponding reaction device is replaced according to the needs of the chemical reaction.

[0061] The displacement table can be a piezoelectric displacement table, mainly including a micrometer stroke displacement table and a three-dimensional piezoelectric displacement table. The three-dimensional piezoelectric displacement table has an XY direction displacement accuracy of 8 nm and a Z direction displacement accuracy of 2.5 nm. The two displacement tables are used to realize the spatial position locking and precise movement of the chemical reaction-quantum sensing integrated sample cell.

[0062] The chemical reaction-quantum sensing integrated sample cell containing diamond is prepared by the following method:

[0063] First, the diamond is pretreated to form a carboxylated surface. During the pretreatment, a chemical vapor deposition (CVD) block diamond (size 3mm*3mm*0.1mm) is selected, ion implanted and annealed to form a diamond sample with a concentration of 1PPM and an average color center distribution depth of about 5-30 nm. Subsequently, the diamond is cleaned with piranha solution at 80 degrees Celsius for 4 hours and ultrasonic cleaned with ultrapure water for 20 minutes. The purpose is to clean the surface impurities and form a carboxylated surface on the diamond.

[0064] Then, an electromagnetic field simulation software is used to design and prepare the microwave radiation structure (PCB structure, surface waveguide structure), as shown in Figure 3 The PCB board is used to receive the microwave signal transmitted from the microwave module and radiate. In order to make the signal have high transmission efficiency, the design of the PCB structure should satisfy the best return loss (S11 parameter) of the target signal 2.8-3GHz. At the same time, a layer of surface waveguide is prepared on the surface of the diamond through micro-nano processing technology such as photolithography and magnetron sputtering. The PCB board is connected outside the surface waveguide. The connection between the surface waveguide and the PCB is realized by flying wire to ensure low-loss transmission of the microwave signal. In this way, the radiated microwave of the PCB board is radiated to the NV color center of the diamond at close range through the surface waveguide.

[0065] Next, after fixing the sample to be tested (such as a catalyst, a nanoparticle or a biological sample) on the exposed surface of the diamond, the sample to be tested is spin-coated on the exposed surface of the diamond by being configured as a suspension. The spin-coating parameters can be: rotation speed 3000 rpm, time 30 s. In order to ensure that the sample to be tested is as firmly dispersed on the surface as possible, the sample to be tested can be connected to the surface of the diamond by heat incubation or chemical grafting, thereby completing the fixation of the sample to be tested.

[0066] Finally, the diamond substrate with the sample to be tested is sealed and packaged in a solid-liquid interface configuration or a solid-gas interface configuration to form a chemical reaction-quantum sensing integrated sample cell containing diamond. As shown in Figure 4 specifically, in the solid-gas interface configuration, the resin-printed sample cell shell is sealed and fixed on the upper side of the diamond connected with the PCB by polydimethylsiloxane (PDMS), and the gas outlet and the gas outlet are respectively connected with the gas injection pump for subsequent reaction occurrence. The temperature probe is fixed on the side of the diamond for real-time temperature feedback. In the solid-liquid interface configuration, the resin sample cell shell is also used to package the bottom diamond and the PCB, and the reaction medium (such as water or PBS buffer) is injected, and the air-tight isolation is realized by PDMS sealing, and the liquid inlet and the liquid outlet are connected with the liquid injection pump for subsequent reaction occurrence. The temperature probe is fixed in the solution for real-time temperature feedback.

[0067] In the embodiment, the electromagnet module is controlled by the control and processing module to apply a continuously adjustable magnetic field to the diamond in the chemical reaction-quantum sensing integrated sample cell and maintain the NV color center of the diamond in a certain axis aligned with the magnetic field, so as to exclude the influence of other off-axis color centers and improve the contrast of the measurement signal. Specifically, the electromagnet module includes a set of five-axis electromagnets, which can be used to apply a magnetic field in any direction at the diamond, with a magnetic field strength range of [-250, +250] Gauss and a resolution of 1 Gauss. It also includes a programmable DC power supply controlled by the control and processing module, which outputs adjustable DC to regulate the magnetic field strength output by the five-axis electromagnets.

[0068] In the embodiment, the microwave module is controlled by the control and processing module to apply microwave and radio frequency signals to the diamond in the chemical reaction-quantum sensing integrated sample cell, so that the spin quantum state of the NV color center of the diamond evolves, so as to perform subsequent physical field sensing and spin quantum state readout. The microwave module can generate a continuously adjustable microwave signal with a frequency of 0-13 GHz by using a microwave source and a radio frequency source, cooperating with a microwave switch 1 and a microwave switch 2, and outputting pulsed microwave under the control of the control and processing module. The microwave is delivered to the chemical reaction-quantum sensing integrated sample cell containing the diamond through a coaxial stable phase cable. Specifically, the surface waveguide connected to the PCB and the diamond in sequence transmits the microwave to the diamond NV color center. The pulse sequence of the generated microwave signal is generated by an arbitrary waveform generator (AWG) in the control and processing module.

[0069] In the embodiment, the optical imaging module is controlled by the control and processing module to provide light source for the occurrence of various chemical reactions, to initialize the spin quantum state of the diamond NV color center, and to perform real-time in-situ fluorescence imaging on the diamond NV color center. Specifically, the optical imaging module includes a laser system, an acousto-optic modulator, a first optical path, an objective lens, a second optical path, and an imaging device. The outgoing laser of the laser system passes through the acousto-optic modulator and is modulated into pulsed laser by the control and processing module, and then passes through the first optical path and the objective lens to irradiate the diamond surface in the chemical reaction-quantum sensing integrated sample cell. The fluorescence signal of the diamond NV color center excited by the laser in the sample cell is collected by the objective lens and then passes through the second optical path to be detected and collected by the imaging device. The first optical path includes a fiber system, a long-pass dichroic mirror (650 nm), etc. The second optical path includes a long-pass dichroic mirror shared with the first optical path, a long-pass filter (550 nm), etc.

[0070] The laser system mainly includes two types of laser light sources. One is used for exciting and detecting the NV color center, mainly a solid-state laser with a wavelength of 532 nm (power 0-5 W continuously adjustable), and the other is used to cooperate to make various chemical reactions occur, such as solid-state lasers with wavelengths of 473 nm (power 0-500 mW continuously adjustable) and 365 nm (power 0-500 mW continuously adjustable). The 532 nm laser is modulated into pulsed laser by an acousto-optic modulator (AOM, bandwidth 110 MHz), the pulsed laser is coupled by an optical fiber to perform spot shaping, and finally focused to the diamond surface by a beam splitter prism and an objective lens to excite the NV color center and initialize the NV color center. The fluorescence signal of the color center after excitation is collected by the objective lens (magnification 100 times), and then collected by the imaging device after passing through the 650 nm long-pass dichroic mirror and the 550 nm long-pass filter. In addition, the 365 nm laser is used to start the titanium dioxide photocatalytic reaction, and the 473 nm laser is used for bacterial staining observation in the biomineralization reaction. In other reaction systems, the two lasers can be replaced by other wavelengths to meet the corresponding experimental needs.

[0071] The imaging device includes an sCMOS imaging camera and a single-photon detector. The fluorescence of the NV color center collected by the objective lens passes through the long-pass dichroic mirror and then through the long-pass filter, which is divided into two by the long-pass filter and enters the sCMOS imaging camera and the single-photon detector, respectively. In the wide-field imaging configuration, the sCMOS imaging camera is used to collect the fluorescence signal, the camera field of view is maximum 100 μm x 100 μm, and the acquisition speed is highest 20 fps. At this time, the first optical path also has a lens for converging the laser entering the objective lens, which is specifically arranged between the fiber system and the long-pass dichroic mirror. In the confocal imaging configuration, the single-photon detector is used to collect the fluorescence signal by cooperating with the time-correlated single-photon counting and the acquisition card. The photon counting in the specified readout interval is completed by the time-correlated photon counter or the acquisition card, and the time resolution can reach nanoseconds.

[0072] In the embodiment, the control and processing module is configured to set a corresponding control strategy for each type of chemical reaction measurement, control the working time sequence of the electromagnet module, the microwave module, and the optical imaging module according to the control strategy, and process the real-time in-situ imaging fluorescence information and reconstruct an image to obtain an imaging result.

[0073] As shown in Figure 5 , the control and processing module includes a workstation, an arbitrary waveform generator, and a processing unit, wherein the workstation is configured to send start, stop, or other special instructions to instruments in each module that meet various communication protocols, the arbitrary waveform generator is configured to send a measurement pulse sequence in the control strategy to each instrument involved in the sequence for clock synchronization, and the processing unit is configured to process real-time in-situ imaging data and reconstruct an image to obtain an imaging result.

[0074] The control strategy is designed based on the electronic energy level structure of diamond NV color centers. The electronic spin ground state of diamond NV color centers contains degenerate ms = ± 1 and ms = 0 states, and there is a zero-field splitting of 2.87 GHz between the two states. When the NV color center is excited, the spin in the excited state ms = ± 1 will have a certain probability of transition back to the ms = 0 ground state, and the spin in the excited state ms = 0 will also transition back to the ms = 0 ground state, which means that when the NV color center is irradiated with laser for a long time, the color center can be initialized to the ms = 0 state. Without an external magnetic field, a microwave field with a frequency corresponding to the zero-field splitting energy level can be used to manipulate the spin state of the color center.

[0075] Based on the above-mentioned electronic energy level structure of diamond NV color centers, a part of the basic microwave pulse sequence control strategy is designed: specifically, a laser pulse with a pulse width of 100 microseconds (wavelength 532 nm) is used to excite the NV color center to initialize the color center; the spin state distribution is detected according to the change of the collected fluorescence signal through the imaging pulse of the sCMOS camera or the single photon counting module (SPCM) in the single photon detector; the spin state of the initialized NV color center is phase-evolved through the microwave pulse, and then coupled with the physical field to be measured.

[0076] On the basis of the basic microwave pulse sequence, a measurement pulse sequence corresponding to the required physical quantity to be measured is quickly generated as another part of the control strategy according to the required physical quantity to be measured, and the measurement pulse sequence is output to the arbitrary waveform generator, as shown in Figure 6As shown, based on the measurement pulse sequence control the working timing of the electromagnet module, microwave module, and optical imaging module, including: continuous wave optical detection magnetic resonance (CW-ODMR) sequence for measuring magnetic field, current, pulsed optical detection magnetic resonance (Pulsed-ODMR) sequence for temperature, electric field and stress measurement, longitudinal relaxation (T1) relaxometry sequence for free radical and paramagnetic ion concentration measurement, double electron-electron resonance (DEER) sequence for free radical and other species analysis, such as Figure 7 As shown.

[0077] The specific process of data processing and image reconstruction of the fluorescence signal of real-time in-situ imaging by the processing unit includes:

[0078] (a) Signal extraction: extracting the reference fluorescence signal of diamond NV color centers from the in-situ imaging fluorescence information by the experimental method of signal / reference frame to remove background interference;

[0079] (b) Line fitting: fitting the fluorescence trajectory of each pixel point in the reference fluorescence information, extracting the information value contained in the sequence, including: extracting the energy level splitting and zero field splitting value in the CW-ODMR sequence or Pulsed-ODMR sequence by Lorentz line fitting, extracting the relaxation rate value in the T1 relaxometry sequence by relaxation line fitting, and extracting the resonance frequency value in the DEER sequence by multi-Gaussian fitting;

[0080] (c) Chemical reaction parameter calculation: calculating the parameters related to the chemical reaction process according to the information value extracted by the line fitting, including: calculating the magnetic property of the chemical reaction product by the linear relationship between the energy level splitting value and the external magnetic field size, calculating the current in the electrochemical reaction process, calculating the chemical reaction heat and the stress change occurring in the chemical reaction process by the correlation between the change of zero field splitting value and temperature and pressure, calculating the concentration and distribution of paramagnetic ions and free radicals by the quantitative relationship between the relaxation rate value and the intensity of paramagnetic noise, and calculating the species attribution of free radicals and paramagnetic ions by the resonance frequency value;

[0081] (d) Image reconstruction: reconstructing the data obtained by the chemical reaction parameter calculation into two-dimensional or three-dimensional images to display the spatial distribution of the chemical reaction parameters;

[0082] (e) Image denoising: the original image of image reconstruction can also be denoised by using median filtering, Gaussian filtering, deep learning, etc.

[0083] (f) Dynamic display: displaying the dynamic process of chemical reaction by time series image to capture fast reaction events.

[0084] The following gives an experimental example of in-situ dynamic free radical imaging of photocatalytic chemical reaction using the above in-situ chemical reaction imaging method. Specifically, based on the quantum sensing characteristics of diamond NV color centers, the generation, distribution and dynamics of free radicals in the chemical reaction process are realized in-situ, real-time and high spatial resolution imaging. The specific experimental process includes:

[0085] High-quality diamond materials are selected, and NV color center arrays are prepared on the surface thereof through ion implantation and annealing process. The surface of the diamond is chemically treated to ensure its compatibility with the reaction system. Titanium dioxide (TiO2) catalyst is uniformly coated on the surface of the diamond to form dispersed single catalyst particles, and then placed in a sample cell containing a PCB board, deionized water is added and the reaction system is sealed.

[0086] Before the reaction starts, the optical imaging module and the microwave module are turned on. Specifically, the 532nm laser in the optical imaging module is used to excite the diamond NV color center. The fluorescence signal of the excited diamond NV color center is collected by the camera or single-photon detector and converted into an electrical signal, which is transmitted to the control and processing module as baseline data. The microwave module applies a frequency-adjustable microwave field through a microwave antenna to control the spin state of the NV color center to realize sensitive detection of the free radical magnetic signal.

[0087] When the reaction starts, the 365nm laser in the optical imaging module is used to start the photocatalytic reaction. On the one hand, according to the above steps, the longitudinal relaxation (T1relaxometry) sequence is applied to the diamond NV color center. The sCMOS camera in the wide-field imaging of the optical imaging module is used to monitor the fluorescence intensity change of the diamond NV color center in real time, extract the relaxation rate information, and construct the spatiotemporal image of the free radical distribution based on the monitored fluorescence signal. The control and processing module analyzes the intensity and frequency changes of the fluorescence signal to quantitatively calculate the concentration distribution of the free radical and its change rule with time. On the other hand, according to the above steps, the double electron-electron resonance (DEER) sequence is applied to the diamond NV color center. The single-photon detector in the confocal imaging of the optical imaging module is used to detect the fluorescence intensity change of the NV color center in real time, extract the resonance frequency information, and infer the signal related to the attribution of the free radical species.

[0088] The experimental results show that the method of the present application can realize in-situ dynamic monitoring of hydroxyl radicals (·OH) in the photocatalytic water splitting reaction. The imaging results show that:

[0089] (1) Spatial distribution of free radicals: as shown in Figure 8 , the generation of free radicals is mainly concentrated near the active sites of the titanium dioxide catalyst, showing significant spatial non-uniformity;

[0090] (2) Dynamic changes over time: such as Figure 9 As shown, in the initial stage of the reaction, the concentration of free radicals rises rapidly and then tends to stabilize, but the stabilization time varies at different sites, and there is a correlation between sites, indicating a transport mechanism, such as... Figure 10 As shown;

[0091] (3) Free radical species classification: such as Figure 11 As shown, the in-situ ESR spectrum of the chemical reaction indicates that the free radicals generated in situ during the reaction are hydroxyl radicals, and it is further inferred that the movement of holes on the catalyst plays a dominant role in the activation effect.

[0092] The above experimental examples demonstrate the application of the method of this invention in in-situ dynamic free radical imaging of photocatalytic water splitting reactions. This provides a powerful tool for studying the chemical reaction mechanisms involving free radicals, and can be used for catalyst performance evaluation, reaction condition optimization, and the design and development of novel catalytic materials. Furthermore, this invention can be extended to the biomedical field to monitor intracellular free radical metabolic processes, providing new insights for disease diagnosis and treatment.

[0093] The above experimental examples fully verify the feasibility and superiority of the in-situ dynamic free radical imaging method based on diamond NV color centers, laying a technical foundation for research and application in related fields.

[0094] In terms of applications, the in-situ chemical reaction imaging method provided by this invention can also be used for imaging ion distribution in chemical reactions, chemical reaction rate imaging, chemical reaction product distribution imaging, chemical reaction electric field imaging, chemical reaction current imaging, chemical reaction pressure and stress imaging, and chemical reaction thermal imaging.

[0095] Among them, imaging of the distribution of chemical reaction products, such as Figure 12 As shown, a typical chemical reaction system (such as the biomineralization reaction of magnetotactic bacteria) is placed on a diamond surface, and imaging is performed according to the steps described above. By applying a continuous-wave optically probed magnetic resonance (CW-ODMR) sequence to the diamond NV color center and analyzing the calculated magnetic field strength, an image of the spatial distribution of the reaction products (magnetoids) can be obtained. The images show that the biomineralization reaction products (ferric oxide) have obvious magnetic signals, which can be correlated with the structures in the scanning electron microscope images. Simultaneously, combined with large-field observation, such as... Figure 13 As shown, the distribution of biomineralization reaction products across the entire field of view can be observed. Furthermore, following the steps described above, as... Figure 14 As shown, the process of the product's gradual formation within magnetotactic bacteria can be observed through in-situ spatiotemporal resolution imaging, and further analysis can yield a growth kinetic model for the product.

[0096] For thermal imaging of chemical reactions, such asFigure 15 A typical exothermic reaction system (e.g. catalytic combustion of methanol) was placed on the diamond surface and imaged according to the above procedure. By applying a pulsed optical detection magnetic resonance (Pulsed-ODMR) sequence to the diamond NV centers and analyzing the temperature response signal of the measurement spectrum, a two-dimensional spatial distribution image of the reaction heat was reconstructed. The image shows that in the catalytic combustion of methanol reaction system, the surface temperature of the nanocatalyst increased significantly when the reaction started by adding methanol gas, and in the spatial distribution of the reaction heat, the center of the composite catalyst platinum / alumina was the highest, and gradually decreased with the distance.

[0097] The present application uses the high sensitivity and high spatial resolution of diamond NV centers to achieve in-situ and dynamic imaging of chemical reaction processes. By introducing a new imaging scheme, the spatiotemporal resolution and sensitivity of the measurement are significantly improved, and it is expected to realize the measurement of reaction rate kinetics, imaging of reaction product distribution, and imaging of reaction heat in the chemical reaction process, which will provide new tools for the study of chemical reaction mechanism and the optimization of reaction conditions.

[0098] The above specific embodiments have described the technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only the most preferred embodiment of the present application and is not intended to limit the present application. Any modifications, supplements and equivalent replacements made within the principle range of the present application shall be included in the protection scope of the present application.

Claims

1. An in-situ chemical reaction imaging method, characterized by, The method comprises the following steps: Constructing a diamond-containing chemical reaction-quantum sensing integrated sample cell and corresponding imaging configuration required for the reaction, wherein a diamond substrate with a sample to be measured is fixed and enclosed in a solid-liquid interface configuration or a solid-gas interface configuration to form a diamond-containing chemical reaction-quantum sensing integrated sample cell, the chemical reaction-quantum sensing integrated sample cell is combined with a reaction device under the support and precise movement of a displacement table to perform various chemical reactions, and a chemical reaction occurrence module is arranged according to experimental requirements; Before the reaction starts, a continuous adjustable magnetic field is applied to the diamond in the chemical reaction-quantum sensing integrated sample cell, and a certain axis of the NV center of the diamond is aligned with the magnetic field, microwave and laser are output based on a basic pulse sequence to initialize and control the electronic spin state of the diamond NV center, and the intrinsic properties of the diamond are measured; The reaction is started by using the chemical reaction occurrence module, and subsequent measurement is performed, at the start of the reaction, the diamond NV center is excited and controlled according to the measurement pulse sequence corresponding to the physical quantity to be measured in the control strategy, so that the NV center electron spin evolves with the environment physical field, and in the reaction process, the fluorescence intensity change of the diamond NV center is synchronously and dynamically monitored in situ in real time, data processing and image reconstruction are performed based on the fluorescence intensity change, and in-situ imaging results of the chemical reaction are obtained; Wherein, the data processing and image reconstruction based on the fluorescence intensity change comprise: (a) Signal extraction: the reference fluorescence signal of the diamond NV center is extracted from the in-situ imaging fluorescence information by the signal / reference frame experimental method to eliminate the low-frequency noise of the background as much as possible; (b) Spectrum fitting: the fluorescence trajectory of each pixel point in the reference fluorescence information is fitted to extract the information value contained in the sequence, including: the energy level splitting and zero field splitting value is extracted by Lorentz line fitting in the continuous wave light detection magnetic resonance sequence or the pulse light detection magnetic resonance sequence, the relaxation rate value is extracted by relaxation line fitting in the longitudinal relaxation sequence, and the resonance frequency value is extracted by multi-Lorentz fitting in the double electron-electron resonance sequence; (c) Chemical reaction parameter calculation: according to the information value extracted by the spectrum fitting, the parameters related to the chemical reaction process are calculated, including: the magnetism of the chemical reaction product and the current in the electrochemical reaction process are calculated by the linear relationship between the energy level splitting value and the external magnetic field size, the chemical reaction heat and the stress change occurring in the chemical reaction process are calculated by the correlation between the change of the zero field splitting value and the temperature and pressure, the concentration and distribution of paramagnetic ions and free radicals are calculated by the quantitative relationship between the relaxation rate value and the paramagnetic noise intensity, and the species attribution of the free radicals and paramagnetic ions is calculated by the resonance frequency value; (d) Image reconstruction: the data obtained by the chemical reaction parameter calculation is reconstructed into a two-dimensional or three-dimensional image to display the spatial distribution of the chemical reaction parameters; (e) Image denoising: the original image of the image reconstruction is denoised by using median filtering, Gaussian filtering or deep learning method; (f) Dynamic display: the dynamic process of the chemical reaction is displayed by time sequence images to capture the fast reaction events.

2. The process according to claim 1, wherein The diamond-containing chemical reaction-quantum sensing integrated sample cell required for the construction reaction comprises: First, the diamond is pretreated to form a carboxylated surface, and a surface waveguide is prepared on the surface, and a PCB board is connected outside the surface waveguide, which is used to receive and radiate microwave signals transmitted from a microwave module, and the microwave is radiated to the NV center in the diamond at a close range through the surface waveguide; Then, after fixing the sample to be tested on the exposed surface of the diamond substrate, the whole is sealed and packaged in an imaging configuration to form a diamond-containing chemical reaction-quantum sensing integrated sample cell, wherein the imaging configuration comprises a solid-liquid interface configuration and a solid-gas interface configuration.

3. The process according to claim 1, wherein The control strategy comprises: The continuous wave light detection magnetic resonance sequence is used for measuring the magnetic field and the current, the pulsed light detection magnetic resonance sequence is used for measuring the temperature, the electric field and the stress, the longitudinal relaxation sequence is used for measuring the free radical and the paramagnetic ion concentration, and the double electron-electron resonance sequence is used for analyzing the free radical species.

4. The process according to claim 1, wherein A microwave source is controlled by a basic pulse width sequence or a measurement pulse sequence to output pulsed microwaves, and the pulsed microwaves are delivered to the diamond-containing chemical reaction-quantum sensing integrated sample cell through a coaxial phase-stable cable, wherein the microwave source can generate a continuously adjustable microwave signal with a frequency of 0-13 GHz.

5. The process according to claim 1, wherein A continuously adjustable magnetic field is applied to the diamond through an introduced electromagnet module, wherein the electromagnet module comprises a set of five-axis electromagnets, which can be used to apply a magnetic field in any direction at the diamond, the magnetic field strength of the five-axis electromagnets ranges from [-250, +250] Gauss, and the resolution reaches 1 Gauss, and the electromagnet module further comprises a programmable direct current power supply controlled by the control and processing module, which outputs adjustable direct current to adjust the magnetic field strength output by the five-axis electromagnets.

6. The process according to claim 1, wherein The diamond NV center is excited and the change of the fluorescence intensity of the diamond NV center is monitored in real time and in situ through an introduced optical imaging module, wherein the optical imaging module comprises a laser system, an acousto-optic modulator, a first light path, an objective lens, a second light path, and an imaging device. The laser system emits laser light, which is modulated into pulsed laser light by the acousto-optic modulator controlled by the control and processing module, and then irradiates the surface of the diamond in the chemical reaction-quantum sensing integrated sample cell through the first light path and the objective lens, and the fluorescence signal of the diamond NV center excited by the laser light is collected by the objective lens and then detected by the imaging device through the second light path. The laser system also emits excitation light for various chemical reactions to meet different wavelength and power requirements.

7. The process according to claim 6, wherein The imaging device comprises an sCMOS imaging camera and a single-photon detector, in a wide-field imaging configuration, the sCMOS imaging camera is used to collect the fluorescence signal of the diamond NV center, and in the first light path, there is also a lens for converging the laser light entering the objective lens; in a confocal imaging configuration, the single-photon detector is used to collect the fluorescence signal of the diamond NV center.

8. The process according to claim 1, wherein The in-situ chemical reaction imaging is controlled by a control and processing module, which comprises a workstation, an arbitrary waveform generator, and a processing unit, wherein the workstation is used to send start or stop instructions to instruments in each module satisfying various communication protocols, the arbitrary waveform generator sends a measurement pulse sequence in a control strategy to each instrument involved in the sequence for clock synchronization, and the processing unit performs data processing and image reconstruction based on fluorescence intensity changes to obtain imaging results.

9. An in-situ chemical reaction imaging application characterized by, The imaging application adopts the in-situ chemical reaction imaging method of any one of claims 1-8 to achieve in-situ chemical reaction imaging, including free radical distribution imaging, ion distribution imaging, chemical reaction rate imaging, chemical reaction product distribution imaging, chemical reaction electric field imaging, chemical reaction current imaging, chemical reaction pressure and stress imaging, and chemical reaction heat imaging.

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