In-situ chemical reaction imaging method and application

Abstract

The invention discloses an in-situ chemical reaction imaging method and application. The in-situ chemical reaction imaging method comprises the following steps: constructing a diamond-containing chemical reaction-quantum sensing integrated sample cell required by reaction and a corresponding imaging configuration; before the reaction is started, applying a continuously adjustable magnetic field to the diamond and maintaining a certain axis of the NV color center of the diamond to be aligned with the magnetic field, outputting microwaves and laser based on the basic pulse sequence to initialize and regulate the electron spin state of the NV color center of the diamond, and measuring the intrinsic attribute of the diamond; at the beginning of the reaction, exciting and regulating the diamond NV color center according to a measurement pulse sequence corresponding to the physical quantity to be measured contained in the control strategy, so that the NV color center electron spin and the environmental physical field are evolved, and the fluorescence intensity change of the diamond NV color center is synchronously and dynamically monitored in situ in real time in the reaction process; data processing and image reconstruction are carried out based on fluorescence intensity change, and chemical reaction process real-time monitoring and in-situ imaging with large field of view, high sensitivity and high temporal-spatial resolution are considered.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical imaging, and in particular relates to an in-situ chemical reaction imaging method and application. Background Art

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

[0003] Diamond NV center is a quantum system with unique optical and magnetic properties, which can realize high-sensitivity multi-physics field measurement at room temperature. In terms of measurement principle, the ground state of the electronic energy level of NV center is a spin triplet state, which can undergo Zeeman splitting under an external magnetic field, and its energy level structure can be accurately measured by optically detected magnetic resonance (ODMR) technology. In addition, NV center is extremely sensitive to the electric field, magnetic field and temperature changes in the surrounding environment, so it can be used to detect tiny physical and chemical changes produced during chemical reactions.

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

[0005] However, existing research on in-situ chemical reaction imaging methods based on diamond NV centers faces multiple difficulties. For example, the diamond measurement scenario needs to be compatible with the chemical reaction environment, and unnecessary background noise must be suppressed during signal acquisition. At the same time, the system must have high temporal resolution, high spatial resolution, and high sensitivity to detect the kinetic information of the reaction process, and a reasonable measurement scheme must be designed to achieve chemically specific measurements of NV centers. Summary of the invention

[0006] In view of the above, the purpose of the present invention 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 centers to achieve real-time monitoring and imaging of chemical reaction processes in a large field of view.

[0007] To achieve the above-mentioned object of the invention, an in-situ chemical reaction imaging method provided in the embodiment comprises the following steps:

[0008] Construct the chemical reaction-quantum sensing integrated sample pool containing diamond and the corresponding imaging configuration required for the reaction, and deploy the chemical reaction module according to the experimental requirements;

[0009] Before the reaction starts, a continuously adjustable magnetic field is applied to the diamond in the chemical reaction-quantum sensing integrated sample cell and a certain axis of the diamond's NV color center is kept aligned with the magnetic field. Based on the basic pulse sequence, microwaves and lasers are output to initialize and regulate the electronic spin state of the diamond NV color center, and the intrinsic properties of the diamond are measured.

[0010] The chemical reaction module is used to start the reaction and perform subsequent measurements. When the reaction starts, the diamond NV center is excited and regulated according to the measurement pulse sequence corresponding to the physical quantity to be measured contained in the control strategy, so that the NV center electron spin and the environmental physical field evolve. During the reaction, the fluorescence intensity changes of the diamond NV center are monitored synchronously and dynamically in situ in real time. Data processing and image reconstruction are performed based on the fluorescence intensity changes to obtain in situ imaging results of the chemical reaction.

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

[0012] First, diamond is pretreated to form a carboxylated surface, and a surface waveguide is prepared on the surface. A PCB is connected to the outside of the surface waveguide. The PCB is used to receive and radiate microwave signals transmitted from a microwave module. The microwave is radiated to the NV color center in the diamond at a close distance through the surface waveguide.

[0013] Then, after the sample to be tested is fixed on the exposed surface of the diamond substrate, it is completely sealed and packaged in an imaging configuration to form a chemical reaction-quantum sensing integrated sample pool containing 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 pulse microwaves controlled by a basic pulse width sequence or a measurement pulse sequence and delivered to a chemical reaction-quantum sensing integrated sample cell containing diamond via a coaxial phase-stable cable, wherein the microwave source is capable of generating a microwave signal with a continuously adjustable frequency of 0-13 GHz.

[0015] Preferably, a continuously adjustable magnetic field is applied to the diamond through the introduction of an electromagnet module, wherein the electromagnet module includes a set of five-axis electromagnets, which can be used to apply a magnetic field in any direction to the diamond, and the magnetic field strength range is [-250, +250] Gauss, and the resolution reaches 1 Gauss. It also includes a programmable DC power supply, which is controlled by the control and processing module and outputs adjustable DC power to adjust the magnetic field strength output by the five-axis electromagnet.

[0016] Preferably, the diamond NV color center is excited by an introduced optical imaging module and the fluorescence intensity change of the diamond NV color center is monitored in real time and dynamically in situ, 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 output laser of the laser system passes through the acousto-optic modulator, is modulated into a pulse laser by the control and processing module, and then irradiates the diamond surface in the chemical reaction-quantum sensing integrated sample pool through the first optical path and the objective lens. The fluorescence signal of the diamond NV color center in the sample pool excited by the laser is collected by the objective lens and then detected and collected 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 the wide-field imaging configuration, the sCMOS imaging camera is used to collect the fluorescence signal of the diamond NV color center. At this time, the first optical path also has a lens for converging the laser entering the objective lens; in the confocal imaging configuration, the single-photon detector is used to collect the fluorescence signal of the diamond NV color center.

[0020] Preferably, in-situ chemical reaction imaging is controlled by a control and processing module, which includes a workstation, an arbitrary waveform generator, and a processing unit, wherein the workstation is used to send start, stop or other special instructions to 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 performs data processing and image reconstruction based on the change in fluorescence intensity to obtain imaging results.

[0021] Preferably, the control strategy includes:

[0022] The continuous wave optical detection magnetic resonance (CW-ODMR) sequence is used to measure the magnetic field and current, the pulsed optical detection magnetic resonance (Pulsed-ODMR) sequence is used to measure the temperature, electric field and stress, the longitudinal relaxation (T1 relaxometry) sequence is used to measure the concentration of free radicals and paramagnetic ions, and the double electron-electron resonance (DEER) sequence is used to analyze species such as free radicals.

[0023] Preferably, data processing and image reconstruction based on fluorescence intensity changes include:

[0024] (a) Signal extraction: The baseline fluorescence signal of the diamond NV color center is extracted from the fluorescence information of in situ imaging through the signal / reference frame experimental method to eliminate the background low-frequency noise as much as possible;

[0025] (b) Spectral line fitting: Fit the fluorescence trajectory of each pixel in the baseline fluorescence information to extract the information value contained in the sequence, including: extracting the energy level splitting and zero-field splitting values ​​through Lorentzian line fitting in CW-ODMR sequence or Pulsed-ODMR sequence, extracting the relaxation rate value through relaxation line fitting in T1 relaxometry sequence, and extracting the resonance frequency value through multi-Lorentzian fitting in DEER sequence;

[0026] (c) Calculation of chemical reaction parameters: Calculate the parameters related to the chemical reaction process based on the information values ​​extracted by spectral line fitting, including: calculate the magnetism of the chemical reaction products and the current during the electrochemical reaction through the linear relationship between the energy level splitting value and the external magnetic field; calculate the heat of the chemical reaction and the stress change during the chemical reaction through the correlation between the change of the zero-field splitting value and the temperature and pressure; calculate the concentration and distribution of paramagnetic ions and free radicals through the quantitative relationship between the relaxation rate value and the paramagnetic noise intensity; and calculate the species attribution of free radicals and paramagnetic ions through the resonance frequency value;

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

[0028] (e) Image denoising: Use median filtering, Gaussian filtering, or deep learning methods to denoise the original image for image reconstruction;

[0029] (f) Dynamic display: The dynamic process of chemical reactions can be displayed through time series images to capture rapid reaction events.

[0030] To achieve the above-mentioned purpose of the invention, an embodiment of the present invention further provides an in-situ chemical reaction imaging application, which adopts the above-mentioned in-situ chemical reaction imaging method, and the in-situ chemical reaction imaging realized includes 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 thermal imaging, etc.

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

[0032] (1) High sensitivity: This method is based on the imaging method of diamond NV color center, and has extremely high sensitivity to light, electricity, magnetism, heat and other signals involved in the chemical reaction process. For example: This method has a strong detection ability for the high-frequency magnetic signal of free radicals, and can detect the concentration of 5 free radicals per pixel;

[0033] (2) High temporal-spatial resolution: Based on the wide-field microscopy imaging technology of the optical imaging module in the method, the spatial resolution can reach hundreds of nanometers, which can be used to clearly determine the active sites on the catalyst surface; combined with the control and processing modules in the method, the temporal resolution can reach milliseconds, which can quickly capture the changes in physical quantities during chemical reactions;

[0034] (3) In-situ and non-destructive: The method of the present invention does not require sampling or labeling of the reaction system, and can achieve the synchronization of chemical reaction and NV color center quantum sensing. The parameter changes of the chemical reaction system are calculated based on the NV color center imaging results, thus achieving true in-situ and real-time monitoring.

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

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

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

[0039] Figure 3 is a schematic diagram of the structure of a chemical reaction-quantum sensing integrated sample cell provided in an embodiment;

[0040] Figure 4 are imaging configurations of different reaction interfaces provided in the embodiments;

[0041] Figure 5 is a control schematic diagram of a control and processing module provided in an embodiment;

[0042] Figure 6 is a schematic diagram of a sequence design interface provided in an embodiment;

[0043] Figure 7 The energy level structure of the NV color center and the pulse control strategy corresponding to the multi-modal measurement provided in the embodiment;

[0044] Figure 8 This is an in-situ free radical imaging diagram of a photocatalytic reaction provided in an embodiment;

[0045] Fig. 9 It is a spatiotemporal dynamic imaging diagram of free radicals in a photocatalytic reaction provided by an embodiment;

[0046] Fig.10 It is the active site transfer mechanism within the catalyst particles in the photocatalytic reaction provided by the embodiment;

[0047] Fig.11 is an in-situ ESR spectrum of a chemical reaction provided in an embodiment;

[0048] Fig.12 It is a magnetic imaging image of biomineralization reaction provided in the embodiment;

[0049] Fig.13 is a distribution diagram of chemical reaction products provided in the embodiment;

[0050] Fig.14 The in-situ spatiotemporal resolution imaging and dynamics measurement of magnetosomes provided in the embodiment;

[0051] Fig.15 It is a thermal imaging diagram of a chemical reaction provided in an embodiment. DETAILED DESCRIPTION

[0052] To make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

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

[0054] Construct the chemical reaction-quantum sensing integrated sample pool containing diamond and the corresponding imaging configuration required for the reaction, and deploy the chemical reaction module according to the experimental requirements

[0055] Before the reaction starts, a continuously adjustable magnetic field is applied to the diamond in the chemical reaction-quantum sensing integrated sample cell and a certain axis of the diamond's NV color center is kept aligned with the magnetic field. Based on the basic pulse sequence, microwaves and lasers are output to initialize and regulate the electronic spin state of the diamond NV color center, and the intrinsic properties of the diamond are measured.

[0056] The chemical reaction module is used to start the reaction and perform subsequent measurements. When the reaction starts, the diamond NV center is excited and regulated according to the measurement pulse sequence corresponding to the physical quantity to be measured contained in the control strategy, so that the NV center electron spin and the environmental physical field evolve. During the reaction, the fluorescence intensity changes of the diamond NV center are monitored synchronously and dynamically in situ in real time. Data processing and image reconstruction are performed based on the fluorescence intensity changes to obtain in situ imaging results of the chemical reaction.

[0057] The above steps achieve real-time monitoring and in-situ imaging of chemical reaction processes with large field of view, high sensitivity, high spatiotemporal resolution, etc. During the reaction, the experimental parameters can be optimized, the contrast of physical quantity measurement and time resolution can be weighed, and the measurement pulse sequence can be adjusted according to the time scale of chemical pronunciation to achieve in-situ dynamic imaging with spatiotemporal resolution.

[0058] The embodiment also provides an optional supporting device for realizing the above-mentioned in-situ chemical reaction imaging reaction, such as Figure 2 It includes: a chemical reaction module, an optical imaging module, a microwave module, an electromagnet module, and a control and processing module.

[0059] In an embodiment, the chemical reaction module includes a reaction device supporting various chemical reactions, a chemical reaction-quantum sensing integrated sample pool containing diamond, and a translation stage, wherein the chemical reaction-quantum sensing integrated sample pool cooperates with the reaction device to perform various chemical reactions under the support and precise movement of the translation stage.

[0060] Among them, the reaction devices include temperature control devices used in biochemical reactions such as living cells, fluid circulation devices used in liquid phase reactions, gas pump devices used in gas phase reactions, electrochemical workstations used in electrochemical reactions, etc. When applied, the reaction device corresponding to the chemical reaction is replaced according to the needs of the chemical reaction.

[0061] Among them, the displacement stage can adopt a piezoelectric displacement stage, which mainly includes a micron-stroke displacement stage and a three-dimensional piezoelectric displacement stage. The three-dimensional piezoelectric displacement stage has a displacement accuracy of 8nm in the XY direction and a displacement accuracy of 2.5nm in the Z direction. The cooperation of the two displacement stages is used to realize the spatial position locking and precise movement of the chemical reaction-quantum sensing integrated sample pool.

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

[0063] First, the diamond was pretreated to form a carboxylated surface. During the pretreatment, a block of chemical vapor deposition (CVD) diamond (size 3mm*3mm*0.1mm) was selected, and the diamond sample with a concentration of 1PPM and an average distribution depth of color centers of about 5-30 nanometers was formed through ion implantation and annealing. Subsequently, it was cleaned with 80 degrees Celsius piranha wash for 4 hours and ultrapure water for 20 minutes to clean the impurities on the surface and form a carboxylated surface for the diamond.

[0064] Then, electromagnetic field simulation software is used to design and prepare microwave radiation structures (PCB structures, surface waveguide structures), such as Figure 3 As shown, the PCB board is used to receive and radiate the microwave signal transmitted from the microwave module. In order to make the signal have high transmission efficiency, the design of the PCB structure should meet the optimal return loss (S11 parameter) of the target signal at 2.8-3GHz. At the same time, a layer of surface waveguide is prepared on the surface of the diamond by micro-nano processing such as photolithography and magnetron sputtering, and the PCB board is connected to the outside of the surface waveguide. Specifically, the surface waveguide and the PCB are connected by flying wires to ensure low-loss transmission of microwave signals. In this way, the radiated microwaves of the PCB board are radiated to the NV color center of the diamond at a close distance through the surface waveguide.

[0065] Next, after fixing the sample to be tested (such as catalyst, nanoparticles or biological samples, etc.) on the exposed surface of the diamond, the sample to be tested is specifically spin-coated on the exposed surface of the diamond by configuring it into a suspension, and the spin-coating parameters may be: rotation speed 3000rpm, time 30s. In order to ensure that the sample to be tested is dispersed on the surface as firmly as possible, it can be connected to the diamond surface by thermal 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 fixed thereon is sealed and encapsulated in a solid-liquid interface configuration or a solid-gas interface configuration to form a diamond-containing chemical reaction-quantum sensing integrated sample pool. Figure 4 As shown, specifically, in the solid-gas interface configuration, the resin-printed sample pool housing is sealed and fixed on the upper side of the diamond connected to the PCB board through polydimethylsiloxane (PDMS), the air inlet and outlet are respectively connected to the gas injection pump for subsequent reaction, and the temperature probe is fixed on the side of the diamond for real-time temperature feedback. In the solid-liquid interface configuration, the diamond and PCB board at the bottom are also encapsulated using a resin sample pool housing, and the reaction medium (such as water or PBS buffer) is injected, and airtight isolation is achieved through PDMS sealing, the liquid inlet and outlet are connected to the liquid injection pump for subsequent reaction, and 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 pool and maintain a certain axis of the NV color center of the diamond aligned with the magnetic field to eliminate the influence of other off-axis color centers to 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 to the diamond, and the magnetic field strength range is [-250, +250] Gauss, and the resolution reaches 1 Gauss, and also includes a programmable DC power supply, which is controlled by the control and processing module and outputs adjustable DC to adjust the magnetic field strength output by the five-axis electromagnet.

[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 pool, so that the NV color center spin quantum state of the diamond evolves, so as to perform subsequent physical field perception and spin quantum state readout. The specific microwave module can generate a microwave signal with a continuously adjustable frequency of 0-13 GHz through a microwave source and a radio frequency source, and cooperates with microwave switch 1 and microwave switch 2. The control and processing module outputs pulse microwaves, and delivers them to the chemical reaction-quantum sensing integrated sample pool containing diamond through a coaxial phase-stable cable. It is specifically connected to the surface waveguide of the PCB and the diamond in turn to transmit the microwave to the diamond NV color center. The pulse sequence that generates the 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 a light source for the occurrence of various chemical reactions, initialize the spin quantum state of the diamond NV color center, and perform real-time in-situ fluorescence imaging of 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 output laser of the laser system passes through the acousto-optic modulator, is modulated into a pulsed laser by the control and processing module, and then irradiates the diamond surface in the chemical reaction-quantum sensing integrated sample pool through the first optical path and the objective lens. The fluorescence signal of the diamond NV color center in the sample pool is excited by the laser and collected by the objective lens and then detected and collected by the imaging device through the second optical path. The first optical path includes an optical fiber system, a long-pass dichroic mirror (650nm), etc. The second optical path includes a long-pass dichroic mirror and a long-pass color filter (550nm) shared with the first optical path.

[0070] The laser system mainly includes two types of laser light sources, one is used to excite and detect NV color centers, mainly solid lasers with a wavelength of 532nm (power 0-5W continuously adjustable), and the other is used to cooperate with various chemical reactions, such as: 473nm (power 0-500mW continuously adjustable) and 365nm (power 0-500mW continuously adjustable) solid lasers. The 532nm laser is modulated by an acousto-optic modulator (AOM, bandwidth 110MHz) to form a pulsed laser, which is coupled by optical fiber for spot shaping, and finally focused on the diamond surface through a beam splitter and an objective lens to excite the NV color center and initialize the NV color center. The fluorescence signal after the color center is excited is collected by an objective lens (magnification 100 times) and then collected by an imaging device after passing through a 650nm long-pass dichroic mirror and a 550nm long-pass filter. In addition, the 365nm laser is used to start the titanium dioxide photocatalytic reaction, and the 473nm laser is used for bacterial staining experimental observation in the biomineralization reaction. In other reaction systems, these two lasers can be replaced with 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 a long-pass dichroic mirror and then a long-pass filter, and 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, an sCMOS imaging camera is used to collect fluorescence signals. The camera has a maximum field of view of 100μm×100μm and a maximum acquisition speed of 20fps. At this time, the first optical path also has a lens for converging the laser entering the objective lens. The specific lens is arranged between the optical fiber system and the long-pass dichroic mirror. In the confocal imaging configuration, a single-photon detector is used to collect fluorescence signals in conjunction with time-correlated single-photon counting and an acquisition card. The time-correlated photon counter or acquisition card completes the photon counting in the specified readout interval, and the time resolution can reach nanoseconds.

[0072] In the embodiment, the control and processing module is used to set a corresponding control strategy for the measurement of each type of chemical reaction, and to control the working timing of the electromagnet module, the microwave module, and the optical imaging module according to the control strategy. It is also used to perform data processing and image reconstruction on the fluorescence information of real-time in-situ imaging to obtain imaging results.

[0073] like Figure 5 As shown, the control and processing module includes a workstation, an arbitrary waveform generator, and a processing unit, wherein the workstation is used to send start, stop or other special instructions to 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 is used to perform data processing and image reconstruction on real-time in-situ imaging data to obtain imaging results.

[0074] The control strategy is designed based on the electronic energy level structure of the diamond NV color center. The ground state of the electronic spin of the diamond NV color center includes the degenerate ms=±1 state and ms=0 state, and there is a zero-field splitting of 2.87GHz between these two states. When the NV color center is excited, the spin in the excited state ms=±1 will have a certain probability of transitioning back to the ms=0 ground state, and the spin in the excited state ms=0 will also still transition back to the ms=0 ground state, which means that when the NV color center is irradiated with a laser for a long time, the color center can be initialized to the ms=0 state. In the absence of an external magnetic field, the spin state of the color center can be manipulated using a microwave field with a frequency corresponding to the zero-field splitting energy level.

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

[0076] In addition to the basic microwave pulse sequence transmission, the measurement pulse sequence of the corresponding parameters is quickly generated according to the required physical quantity to be measured as another part of the control strategy, and the measurement pulse sequence is output to the arbitrary waveform generator, such as Figure 6As shown, the working sequence of the electromagnet module, microwave module, and optical imaging module is controlled based on the measurement pulse sequence, including: a continuous wave optical detection magnetic resonance (CW-ODMR) sequence is used to measure the magnetic field and current, a pulsed optical detection magnetic resonance (Pulsed-ODMR) sequence is used to measure the temperature, electric field, and stress, a longitudinal relaxation (T1) relaxometry sequence is used to measure the concentration of free radicals and paramagnetic ions, and a double electron-electron resonance (DEER) sequence is used to analyze species such as free radicals. Figure 7 shown.

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

[0078] (a) Signal extraction: The reference fluorescence signal of the diamond NV color center is extracted from the fluorescence information of in situ imaging through the signal / reference frame experimental method to remove background interference;

[0079] (b) Spectral line fitting: Fit the fluorescence trajectory of each pixel in the baseline fluorescence information to extract the information value contained in the sequence, including: extracting the energy level splitting and zero-field splitting values ​​through Lorentzian line fitting in CW-ODMR sequence or Pulsed-ODMR sequence, extracting the relaxation rate value through relaxation line fitting in T1 relaxometry sequence, and extracting the resonance frequency value through multi-Gaussian fitting in DEER sequence;

[0080] (c) Calculation of chemical reaction parameters: Calculate the parameters related to the chemical reaction process based on the information values ​​extracted by spectral line fitting, including: calculate the magnetism of the chemical reaction products and the current during the electrochemical reaction through the linear relationship between the energy level splitting value and the external magnetic field; calculate the heat of the chemical reaction and the stress change during the chemical reaction through the correlation between the change of the zero-field splitting value and the temperature and pressure; calculate the concentration and distribution of paramagnetic ions and free radicals through the quantitative relationship between the relaxation rate value and the paramagnetic noise intensity; and calculate the species attribution of free radicals and paramagnetic ions through the resonance frequency value;

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

[0082] (e) Image denoising: Median filtering, Gaussian filtering, deep learning and other methods can also be used to denoise the original image of image reconstruction;

[0083] (f) Dynamic display: The dynamic process of chemical reactions can be displayed through time series images to capture rapid reaction events.

[0084] The following is an experimental example of using the above in-situ chemical reaction imaging method to perform in-situ dynamic free radical imaging of photocatalytic chemical reactions. Based on the quantum sensing characteristics of diamond NV color centers, in-situ, real-time, and high spatial resolution imaging of free radical generation, distribution, and dynamics during chemical reactions is achieved. The specific experimental process includes:

[0085] High-quality diamond materials were selected, and NV color center arrays were prepared on their surfaces through ion implantation and annealing processes. The diamond surface was chemically treated to ensure its compatibility with the reaction system. Titanium dioxide (TiO 2 ) The catalyst is evenly coated on the diamond surface to form dispersed single catalyst particles, which are then placed in a sample pool containing a PCB board, deionized water is added and the reaction system is sealed.

[0086] Before the reaction starts, the optical imaging module and 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 a camera or a 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 regulate the spin state of the NV color center to achieve sensitive detection of free radical magnetic signals.

[0087] At the beginning of the reaction, the 365nm laser in the optical imaging module is used to start the photocatalytic reaction. On the one hand, according to the above steps, by applying the longitudinal relaxation (T1relaxometry) sequence to the diamond NV color center, the sCMOS camera with wide-field imaging in the optical imaging module is combined with time-resolved signal acquisition to monitor the fluorescence intensity changes of the diamond NV color center in real time, extract relaxation rate information, and build a spatiotemporal image of the free radical distribution based on the monitored fluorescence signal in combination with the control and processing module, and analyze the intensity and frequency changes of the fluorescence signal at the same time, quantitatively calculate the concentration distribution of the free radical and its change law over time. On the other hand, according to the above steps, by applying the double electron-electron resonance (DEER) sequence to the diamond NV color center, the single-photon detector with co-focusing imaging in the optical program module is combined with the acquisition card to detect the fluorescence intensity changes of the NV color center in real time during the reaction, extract the resonance frequency information, and infer the signal related to the free radical species.

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

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

[0090] (2) Dynamic changes in time: Fig. 9 As shown, at the beginning of the reaction, the concentration of free radicals rises rapidly and then stabilizes, but the stability time at different sites is different, and there is a correlation between the sites, with a transfer mechanism, such as Fig.10 As shown;

[0091] (3) Free radical species classification: Fig.11 As shown, the in-situ ESR spectrum of the chemical reaction determined that the free radicals generated in-situ during the reaction were hydroxyl radicals, and it was further inferred that the movement of holes on the catalyst played a leading role in the activation effect.

[0092] The above experimental examples demonstrate the application of the method of the present invention in the in-situ dynamic free radical imaging of the photocatalytic water splitting reaction, which provides a powerful tool for studying the chemical reaction mechanism involving free radicals, and can be used for catalyst performance evaluation, reaction condition optimization, and the design and development of new catalytic materials. In addition, the present invention can also be extended to the biomedical field to monitor the free radical metabolic process in cells, providing new ideas for disease diagnosis and treatment.

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

[0094] The in-situ chemical reaction imaging method provided by the present invention can also be used for ion distribution imaging 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, the distribution imaging of chemical reaction products is Fig.12 As shown in the figure, a typical chemical reaction system (such as the biomineralization reaction of magnetotactic bacteria) is placed on the diamond surface and imaged according to the above steps. By applying a continuous light detection 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 product (magnetosome) can be obtained. The image shows that the biomineralization reaction product (ferroferric oxide) has a clear magnetic signal that can be correlated with the structure in the scanning electron microscope image. At the same time, with the observation of a large field of view, such as Fig.13 As shown in Figure 1, the distribution of biomineralization reaction products in the entire field of view can be observed. In addition, according to the above steps, Fig.14 As shown, the gradual generation process of the product in magnetotactic bacteria can be observed through in situ spatiotemporal resolution imaging, and further analysis can obtain the growth kinetics model of the product.

[0096] For thermal imaging of chemical reactions, such as Fig.15 As shown in the figure, a typical exothermic reaction system (such as methanol catalytic combustion reaction) is placed on the diamond surface and imaged according to the above steps. By applying a pulsed optical detection magnetic resonance sequence (Pulsed-ODMR) to the diamond NV color center and analyzing the temperature response signal of the measurement spectrum, a two-dimensional spatial distribution image of the reaction heat can be reconstructed. The image shows that in the methanol catalytic combustion reaction system, when methanol gas is added to start the reaction, the surface temperature of the nanocatalyst rises significantly. At the same time, in terms of the spatial distribution of the reaction heat, the central area of ​​the composite catalyst platinum / aluminum oxide is the highest and gradually decreases with increasing distance.

[0097] The present invention utilizes the high sensitivity and high spatial resolution of diamond NV color centers to achieve in-situ, dynamic imaging of chemical reaction processes. By introducing a new imaging scheme, the temporal and spatial resolution and sensitivity of the measurement are significantly improved. It is expected that the reaction rate kinetics measurement, reaction product distribution imaging, reaction thermal imaging, etc. in the chemical reaction process can be achieved, which will provide a new tool for the study of chemical reaction mechanisms and the optimization of reaction conditions.

[0098] The specific implementation methods described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above is only the most preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, supplements and equivalent substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An in-situ chemical reaction imaging method, characterized in that: The following steps are involved: Construct the chemical reaction-quantum sensing integrated sample pool containing diamond and the corresponding imaging configuration required for the reaction, and deploy the chemical reaction module according to the experimental requirements; Before the reaction starts, a continuously adjustable magnetic field is applied to the diamond in the chemical reaction-quantum sensing integrated sample cell and a certain axis of the diamond's NV color center is kept aligned with the magnetic field. Based on the basic pulse sequence, microwaves and lasers are output to initialize and regulate the electronic spin state of the diamond NV color center, and the intrinsic properties of the diamond are measured. The chemical reaction module is used to start the reaction and perform subsequent measurements. When the reaction starts, the diamond NV center is excited and regulated according to the measurement pulse sequence corresponding to the physical quantity to be measured contained in the control strategy, so that the NV center electron spin and the environmental physical field evolve. During the reaction, the fluorescence intensity changes of the diamond NV center are monitored synchronously and dynamically in situ in real time. Data processing and image reconstruction are performed based on the fluorescence intensity changes to obtain in situ imaging results of the chemical reaction.

2. The in-situ chemical reaction imaging method according to claim 1, characterized in that: Construct the diamond-containing chemical reaction-quantum sensing integrated sample cell required for the reaction, including: First, the diamond is pretreated to form a carboxylated surface, and a layer of surface waveguide is prepared on the surface. A PCB board is connected to the outside of the surface waveguide. The PCB board is used to receive and radiate microwave signals transmitted from a microwave module. The microwave is radiated to the NV color center in the diamond at a close distance through the surface waveguide. Then, after the sample to be tested is fixed on the exposed surface of the diamond substrate, it is completely sealed and packaged in an imaging configuration to form a chemical reaction-quantum sensing integrated sample pool containing diamond, wherein the imaging configuration includes a solid-liquid interface configuration and a solid-gas interface configuration.

3. The in-situ chemical reaction imaging method according to claim 1, characterized in that: The control strategy includes: The continuous wave light detection magnetic resonance sequence is used to measure the magnetic field and current, the pulsed light detection magnetic resonance sequence is used to measure the temperature, electric field and stress, the longitudinal relaxation sequence is used to measure the concentration of free radicals and paramagnetic ions, and the double electron-electron resonance sequence is used to analyze species such as free radicals.

4. The in-situ chemical reaction imaging method according to claim 1, characterized in that: Data processing and image reconstruction based on fluorescence intensity changes, including: (a) Signal extraction: The baseline fluorescence signal of the diamond NV color center is extracted from the fluorescence information of in situ imaging through the signal / reference frame experimental method to eliminate the background low-frequency noise as much as possible; (b) Spectral line fitting: fitting the fluorescence trajectory of each pixel in the reference fluorescence information to extract the information value contained in the sequence, including: extracting the energy level splitting and zero-field splitting values ​​by Lorentz line fitting in the continuous wave light detection magnetic resonance sequence or the pulse light detection magnetic resonance sequence, extracting the relaxation rate value by relaxation line fitting in the longitudinal relaxation sequence, and extracting the resonance frequency value by multi-Lorentz fitting in the double electron-electron resonance sequence; (c) Calculation of chemical reaction parameters: Calculate the parameters related to the chemical reaction process based on the information values ​​extracted by spectral line fitting, including: calculate the magnetism of the chemical reaction products and the current during the electrochemical reaction through the linear relationship between the energy level splitting value and the external magnetic field; calculate the heat of the chemical reaction and the stress change during the chemical reaction through the correlation between the change of the zero-field splitting value and the temperature and pressure; calculate the concentration and distribution of paramagnetic ions and free radicals through the quantitative relationship between the relaxation rate value and the paramagnetic noise intensity; and calculate the species attribution of free radicals and paramagnetic ions through the resonance frequency value; (d) Image reconstruction: reconstructing the data obtained by calculating the chemical reaction parameters into a two-dimensional or three-dimensional image to display the spatial distribution of the chemical reaction parameters; (e) Image denoising: Use median filtering, Gaussian filtering, or deep learning methods to denoise the original image for image reconstruction; (f) Dynamic display: The dynamic process of chemical reactions can be displayed through time series images to capture rapid reaction events.

5. The in-situ chemical reaction imaging method according to claim 1, characterized in that: A microwave source is used to output pulse microwaves controlled by a basic pulse width sequence or a measurement pulse sequence and delivered to a chemical reaction-quantum sensing integrated sample cell containing diamond via a coaxial phase-stable cable, wherein the microwave source can generate a microwave signal with a continuously adjustable frequency of 0-13 GHz.

6. The in-situ chemical reaction imaging method according to claim 1, characterized in that: The electromagnetic module introduced is used to apply a continuously adjustable magnetic field to the diamond. The electromagnetic module includes a set of five-axis electromagnets that can be used to apply a magnetic field in any direction to the diamond. The magnetic field strength range is [-250, +250] Gauss, and the resolution reaches 1 Gauss. It also includes a programmable DC power supply, which is controlled by the control and processing module and outputs adjustable DC power to adjust the magnetic field strength output by the five-axis electromagnet.

7. The in-situ chemical reaction imaging method according to claim 1, characterized in that: The diamond NV color center is excited by the introduced optical imaging module and the fluorescence intensity change of the diamond NV color center is monitored in real time and dynamically in situ, 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; The output laser of the laser system passes through the acousto-optic modulator, is modulated into a pulse laser by the control and processing module, and then irradiates the diamond surface in the chemical reaction-quantum sensing integrated sample pool through the first optical path and the objective lens. The fluorescence signal of the diamond NV color center in the sample pool excited by the laser is collected by the objective lens and then detected and collected by the imaging device through the second optical path; The laser system also emits excitation light for various chemical reactions to meet different wavelength and power requirements.

8. The in-situ chemical reaction imaging method according to claim 7, characterized in that: 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 color center. At this time, the first optical path also has a lens for converging 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 color center.

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

10. An in-situ chemical reaction imaging application, characterized in that the imaging application adopts the in-situ chemical reaction imaging method described in any one of claims 1-9, and the in-situ chemical reaction imaging achieved includes free radical distribution imaging in chemical reactions, 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 thermal imaging.

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