Electron paramagnetic resonance spectrometer and transient electron paramagnetic resonance spectrum detection method

Abstract

The invention discloses an electron paramagnetic resonance spectrometer and a transient electron paramagnetic resonance spectrum detection method, and relates to the technical field of electron paramagnetic resonance. The electron paramagnetic resonance spectrometer comprises a laser system used for emitting laser to a probe containing an object to be detected; the magnetic field system is used for providing a magnetic field for the probe; the microwave system comprises a microwave generation module, a frequency mixing module and a control module, the microwave generation module is used for generating a first microwave signal and a second microwave signal, the first microwave signal is input into the probe to generate a third microwave signal, and the frequency mixing module obtains a frequency mixing signal according to the second microwave signal and the third microwave signal; the control module is used for controlling the microwave generation module according to the frequency mixing signal, so that the frequencies of the first microwave signal and the second microwave signal are the same as the resonant frequency in the probe; and the acquisition system is used for acquiring a frequency mixing signal according to the trigger signal generated by the laser and obtaining an electron paramagnetic resonance detection result according to the frequency mixing signal.

Description

Technical Field

[0001] The invention relates to the technical field of electron paramagnetic resonance, and in particular to an electron paramagnetic resonance spectrometer and a transient electron paramagnetic resonance spectrum detection method. Background Art

[0002] Electron paramagnetic resonance technology is a specific research method for studying paramagnetic substances with spin greater than zero. However, the lifetimes of paramagnetic free radicals and excited triplet states are usually very short. For example, the lifetime of hydroxyl in aqueous solution is about nanoseconds. Such short-lived free radicals obviously cannot be tested using conventional electron paramagnetic resonance spectrometers. Therefore, an electron paramagnetic resonance detection technology that can perform transient detection is needed. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to some extent. To this end, a first object of the present invention is to provide an electron paramagnetic resonance spectrometer to support the detection of transient states.

[0004] The second object of the present invention is to provide a transient electron paramagnetic resonance spectroscopy detection method.

[0005] To achieve the above-mentioned purpose, the first aspect of the present invention proposes an electron paramagnetic resonance spectrometer, comprising: a laser system, used to emit laser to a probe containing an object to be detected; a magnetic field system, used to provide a magnetic field for the probe; a microwave system, including a microwave generating module, a mixing module and a control module, the microwave generating module is used to generate a first microwave signal and a second microwave signal, the first microwave signal is input into the probe to generate a third microwave signal, the mixing module obtains a mixing signal according to the second microwave signal and the third microwave signal, and the control module is used to control the microwave generating module according to the mixing signal so that the frequencies of the first microwave signal and the second microwave signal are the same as the resonant frequency in the probe; an acquisition system is used to acquire the mixing signal according to a trigger signal generated by the laser, and obtain an electron paramagnetic resonance detection result according to the mixing signal.

[0006] In addition, the electron paramagnetic resonance spectrometer according to the embodiment of the present invention may also have the following additional technical features:

[0007] In one embodiment of the present invention, the laser system includes a controller and a laser, and the laser is used to emit induction light or excitation light to the probe under the control of the controller.

[0008] In one embodiment of the present invention, the electron paramagnetic resonance spectrometer further includes: a trigger system, which is connected to the acquisition system and is used to generate the trigger signal when it is detected that the laser system emits laser, so as to trigger the acquisition system to perform signal acquisition.

[0009] In one embodiment of the present invention, the acquisition system includes an acquisition card, which is used to acquire the mixed signal. The trigger system includes a photosensitive diode and a trigger, and the trigger is connected to the photosensitive diode and the acquisition card; wherein the photosensitive diode is located on a first optical path, and is used to generate an electrical signal when irradiated by a laser, and the first optical path is an optical path of the laser emitted by the laser system; the trigger is used to generate the trigger signal when receiving the electrical signal generated by the photosensitive diode, and send the trigger signal to the acquisition card, so that the acquisition card acquires the mixed signal under the triggering of the trigger signal.

[0010] In one embodiment of the present invention, the acquisition system includes an acquisition card, which is used to acquire the mixed signal, and the trigger system includes a beam splitter, a photosensitive diode and a trigger, and the trigger is connected to the photosensitive diode and the acquisition card; wherein the beam splitter is located on the second optical path, and is used to split the laser on the second optical path into laser on a third optical path and laser on a fourth optical path, the second optical path is the optical path of the laser emitted by the laser system, the third optical path is the optical path from the beam splitter to the photosensitive diode, and the fourth optical path is the optical path from the beam splitter to the probe; the photosensitive diode is used to generate an electrical signal when irradiated by the laser; the trigger is used to generate a trigger signal when receiving the electrical signal generated by the photosensitive diode, and send the trigger signal to the acquisition card, so that the acquisition card acquires the mixed signal under the trigger of the trigger signal.

[0011] In one embodiment of the present invention, the microwave generating module includes: a solid-state microwave source, used to generate the first microwave signal; a directional coupler, connected to a circulator, an attenuator and the solid-state microwave source, used to output the first microwave signal to the circulator and the attenuator; the circulator is used to input the first microwave signal into the probe; the attenuator is used to attenuate the first microwave signal; a phase shifter, connected to the attenuator, used to perform phase shift processing on the attenuated first microwave signal to obtain the second microwave signal, and output the second microwave signal to the mixing module.

[0012] In one embodiment of the present invention, the circulator is further used to obtain the third microwave signal and output the third microwave signal to the frequency mixing module.

[0013] In one embodiment of the present invention, the mixing module is specifically used to: obtain a fourth microwave signal and a fifth microwave signal according to the third microwave signal, multiply the fourth microwave signal by the second microwave signal, and perform low-pass filtering on the multiplication result to obtain a first mixing signal; and multiply the fifth microwave signal by the second microwave signal, and perform low-pass filtering on the multiplication result to obtain a second mixing signal, wherein the fourth microwave signal has the same phase as the third microwave signal, and the fifth microwave signal has a 90-degree phase difference with the third microwave signal.

[0014] In one embodiment of the present invention, the mixing module is further used to obtain the first mixing signal and the second mixing signal according to the following formula:

[0015]

[0016] Wherein, I(t) is the first mixing signal, Q(t) is the second mixing signal, V s is the voltage amplitude of the second microwave signal, is the phase of the second microwave signal, V r is the voltage amplitude of the third microwave signal, is the phase of the third microwave signal.

[0017] In one embodiment of the present invention, the control module is specifically used to: when the phases of the second microwave signal and the third microwave signal are the same, control the microwave generating module to adjust the frequencies of the first microwave signal and the second microwave signal according to the second mixing signal; or, when the phase difference between the second microwave signal and the third microwave signal is 90°, control the microwave generating module to adjust the frequencies of the first microwave signal and the second microwave signal according to the first mixing signal.

[0018] In one embodiment of the present invention, the control module is specifically used to: when the phase of the second microwave signal is the same as the phase of the third microwave signal and the second mixing signal is greater than zero, control the microwave generating module to increase the frequency of the first microwave signal and the second microwave signal; when the phase of the second microwave signal is the same as the phase of the third microwave signal and the second mixing signal is less than zero, control the microwave generating module to reduce the frequency of the first microwave signal and the second microwave signal; or, when the phase of the second microwave signal differs from the phase of the third microwave signal by 90 degrees and the first mixing signal is greater than zero, control the microwave generating module to increase the frequency of the first microwave signal and the second microwave signal; when the phase of the second microwave signal differs from the phase of the third microwave signal by 90 degrees and the first mixing signal is less than zero, control the microwave generating module to reduce the frequency of the first microwave signal and the second microwave signal.

[0019] The second aspect of the present invention proposes a transient electron paramagnetic resonance spectroscopy detection method, which is applied to the above-mentioned electron paramagnetic resonance spectrometer; the method includes: the acquisition system acquires N acquisition units, wherein each of the acquisition units is a unit obtained by the acquisition system performing n times of data acquisition, n is a positive integer greater than 1, and N is a positive integer greater than 1; adjusting the magnetic field provided to the probe, and returning to the step of acquiring N acquisition units by the acquisition system until the number of times the magnetic field is adjusted reaches a preset number; obtaining a three-dimensional spectrum including time, magnetic field strength, and paramagnetic signal strength according to the acquisition unit, and using the three-dimensional spectrum as the detection result.

[0020] In addition, the transient electron paramagnetic resonance spectroscopy detection method according to the embodiment of the present invention may also have the following additional technical features:

[0021] In one embodiment of the present invention, before adjusting the magnetic field provided to the probe, the method further comprises: averaging the N acquisition units acquired by the acquisition system, and obtaining the paramagnetic signal strength according to the average value.

[0022] According to the electron paramagnetic resonance spectrometer and transient electron paramagnetic resonance spectrum detection method of the embodiment of the present invention, the electron paramagnetic resonance spectrometer is set to include: a laser system for emitting laser to a probe containing an object to be detected; a magnetic field system for providing a magnetic field for the probe; a microwave system including a microwave generation module, a frequency mixing module and a control module, the microwave generation module is used to generate a first microwave signal and a second microwave signal, the first microwave signal is input into the probe to generate a third microwave signal, the frequency mixing module obtains a frequency mixing signal according to the second microwave signal and the third microwave signal, and the control module is used to control the microwave generation module according to the frequency mixing signal so that the frequencies of the first microwave signal and the second microwave signal are the same as the resonant frequency in the probe; an acquisition system is used to acquire the frequency mixing signal according to the trigger signal generated by the laser, and obtain the electron paramagnetic resonance detection result according to the frequency mixing signal. Therefore, the microwave system is set to include a microwave generation module, a frequency mixing module and a control module, and through the control of the frequency mixing module and the control module, the frequencies of the first microwave signal and the second microwave signal generated by the microwave generation module are the same as the resonant frequency in the probe, so that the frequency of the microwave generated by the microwave generation module is kept at the resonant frequency, thereby realizing the support of transient electron paramagnetic resonance detection.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of the structure of an example time-resolution electron paramagnetic resonance spectrometer;

[0025] Figure 2 is a structural block diagram of an electron paramagnetic resonance spectrometer according to an embodiment of the present invention;

[0026] Figure 3 It is a working flow chart of an electron paramagnetic resonance spectrometer according to an example of the present invention;

[0027] Figure 4 is a schematic structural diagram of a trigger system according to an embodiment of the present invention;

[0028] Figure 5 is a schematic diagram of the operation of a trigger system according to an example of the present invention;

[0029] Figure 6 is a schematic structural diagram of a trigger system according to another embodiment of the present invention;

[0030] Figure 7 is a schematic structural diagram of an electron paramagnetic resonance spectrometer according to an example of the present invention;

[0031] Figure 8 It is a working schematic diagram of an electron paramagnetic resonance spectrometer according to an example of the present invention;

[0032] Fig. 9 It is a flow chart of a transient electron paramagnetic resonance spectroscopy detection method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The electron paramagnetic resonance spectrometer and the transient electron paramagnetic resonance spectroscopy detection method of the embodiments of the present invention are described below with reference to the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described with reference to the accompanying drawings are exemplary and should not be construed as limiting the present invention.

[0034] To achieve electron paramagnetic resonance, one can use Figure 1 The time resolution of electron paramagnetic resonance spectroscopy is shown.

[0035] Figure 1 The time-resolution electron paramagnetic resonance spectrometer shown includes a digital microwave source, a directional coupler, an attenuator, a phase shifter, a circulator, a mixer, a phase-locked amplifier, an acquisition card, a probe, a magnetic field mechanism, a controller and a laser.

[0036] Figure 1 The principle of the time-resolution electron paramagnetic resonance spectrometer shown is that the sample is placed in a probe, the probe is located in a uniform magnetic field generated by a magnetic field system, and a microwave system inputs a continuous microwave signal into the probe; a laser emits induced light or excitation light to the sample in the probe, so that the sample is in an excited triplet state, and paramagnetic free radicals and excited triplet states absorb microwave energy of a specific wavelength in a given uniform magnetic field, so that electrons in the system transition between different energy levels, thereby generating a paramagnetic signal.

[0037] However, Figure 1 The time-resolution electron paramagnetic resonance spectrometer shown in the figure has the following main technical problems to be solved during implementation:

[0038] 1. The time resolution of signal acquisition is not high: This method involves a light-excited or light-induced EPR spectrometer, which uses a controller (host computer) to send out timing signals to control the laser and the acquisition card to achieve signal acquisition; on the one hand, this method requires accurate measurement of the signal delay from the controller to the laser and from the controller to the acquisition card, so as to perform delay compensation to synchronize the timing signal, and the signal delay compensation debugging workload is large; on the other hand, due to the unstable working delay of the laser, it is difficult to accurately control the time resolution of signal acquisition to the nanosecond level.

[0039] 2. The time resolution of signal processing is not high: The EPR spectrometer in this method uses the modulation technology of high-frequency small modulation field to perform transient EPR detection. A set of modulation fields is added to the magnetic field system, so that the magnetic field system generates a high-frequency modulation field while generating a uniform magnetic field; the signal at this frequency is obtained through a phase-locked amplifier according to the frequency of the modulation field, thereby filtering out clutter signals of other frequencies; but due to the low modulation frequency, it cannot play a role in modulation and demodulation of transient signals.

[0040] Therefore, the present invention proposes Figure 2 Electron paramagnetic resonance spectrometer shown.

[0041] Figure 2 1 is a structural block diagram of an electron paramagnetic resonance spectrometer according to an embodiment of the present invention.

[0042] like Figure 2 As shown, the electron paramagnetic resonance spectrometer 10 includes: a laser system 100, which is used to emit laser to a probe containing an object to be detected; a magnetic field system 200, which is used to provide a magnetic field for the probe; a microwave system 300, which includes a microwave generating module 301, a mixing module 302 and a control module 303, the microwave generating module 301 is used to generate a first microwave signal and a second microwave signal, the first microwave signal is input into the probe to generate a third microwave signal, the mixing module 302 obtains a mixing signal according to the second microwave signal and the third microwave signal, and the control module 303 is used to control the microwave generating module 301 according to the mixing signal, so that the frequencies of the first microwave signal and the second microwave signal are the same as the resonant frequency in the probe; an acquisition system 400, which is used to acquire the mixing signal according to the trigger signal generated by the laser, and obtain the electron paramagnetic resonance detection result according to the mixing signal.

[0043] Specifically, the electron paramagnetic resonance spectrometer 10 includes a laser system 100 , a magnetic field system 200 , a microwave system 300 and a collection system 400 .

[0044] The laser system 100 is used to emit laser to the object to be detected in the probe, and realize the spin polarization of the object to be detected by laser. The microwave system 300 is used to emit microwave to the object to be detected in the probe to stimulate the resonance transition, thereby generating a signal. The magnetic field system 200 is used to emit a magnetic field to the object to be detected in the probe to provide the necessary spin splitting and resonance conditions. The acquisition system 400 is used to collect data after the microwave system 300 emits microwaves to the object to be detected in the probe, and obtain the electron paramagnetic resonance detection result according to the acquisition result.

[0045] Moreover, the microwave system 300 includes a microwave generating module 301, a mixing module 302 and a control module 303. The microwave generating module 301 is used to generate and transmit microwaves to the probe, and the mixing module 302 is used to generate a mixing signal according to the second microwave signal and the third microwave signal, so that the acquisition system 400 can acquire the mixing signal generated by the mixing module 302, and the control module 303 can also obtain the mixing signal generated by the mixing module 302.

[0046] The microwave generating module 301 generates a first microwave signal and a second microwave signal, and transmits microwaves to the probe according to the first microwave signal, and outputs the second microwave signal to the frequency mixing module 302. The object to be detected in the probe will act on the microwaves emitted to the probe. The object to be detected is, for example, a hydroxyl group soluble in water. The object to be detected is an object to be detected placed in the probe, and the effect of the object to be detected on the microwaves emitted to the probe includes absorbing the microwaves. The microwaves emitted to the probe will change after being acted upon by the object to be detected, so that a changed microwave signal can be obtained according to the changed microwaves. The frequency mixing module 302 obtains the changed microwave signal and uses the changed microwave signal as the third microwave signal.

[0047] After obtaining the mixing signal, the control module 303 can determine whether the frequency of the first microwave signal is consistent with the known resonant frequency according to the mixing signal, and control the microwave generating module 301 if they are inconsistent, so that the frequencies of the first microwave signal and the second microwave signal are consistent with the resonant frequency in the probe.

[0048] The acquisition system 400 can perform acquisition when the probe is emitted with laser by the laser system 100, with magnetic field by the magnetic field system 200, and with microwave by the microwave system 300, and obtain an electron paramagnetic resonance detection result according to the acquired mixing signal.

[0049] It should be noted that when obtaining the electron paramagnetic resonance detection result based on the mixing signal, in order to reduce the influence of random errors in the experiment, multiple repeated detections can be set to improve the signal-to-noise ratio by accumulating and averaging the data.

[0050] Specifically, see Figure 3 ,exist Figure 3 In , N represents the number of points collected in each set of experiments, Trigger1, Trigger2, …, TriggerN represent the first repetition experiment, the second repetition experiment, …, the Nth repetition experiment, respectively, and Field1, Field2, …, FieldN represent the first change, the second change, …, the Nth change of the magnetic field in the two-dimensional experiment, respectively. The above points refer to the number of times data is collected in one experimental cycle.

[0051] Assuming that, in one test cycle, data collection needs to be performed n times, and assuming that the data collected in each repeated experiment is a collection unit, then based on Figure 3 The workflow of the electron paramagnetic resonance spectrometer 10 of the process shown is: the acquisition system 400 acquires N acquisition units, wherein each acquisition unit is a unit obtained by the acquisition system 400 performing n data acquisitions, n is a positive integer greater than 1, and N is a positive integer greater than 1; the magnetic field provided to the probe is adjusted, and the acquisition system 400 is returned to acquire N acquisition units until the number of times the magnetic field is adjusted reaches a preset number; a three-dimensional map including time, magnetic field strength, and paramagnetic signal strength is obtained according to the acquisition unit, and the three-dimensional map is used as the detection result.

[0052] Furthermore, the N acquisition units acquired by the acquisition system 400 may be averaged, and the paramagnetic signal strength may be obtained based on the average value.

[0053] That is to say, Figure 3 The rectangular box in the figure represents a minimum task. The laser works once for each minimum task. N represents the number of points collected in each experiment. TriggerN means that the same experiment is repeated N times, and only the accumulation is done. The software performs average processing. This method can improve the signal-to-noise ratio of the detection signal. FieldN means that the magnetic field is a variable in the two-dimensional experiment. The step of magnetic field change can be set according to the experimental requirements.

[0054] After the mixed frequency signal is collected, the electron paramagnetic resonance detection result can be obtained according to the mixed frequency signal. The above electron paramagnetic resonance detection result includes the paramagnetic signal intensity.

[0055] Taking the above paramagnetic signal intensity as an example, the detection result of the above electron paramagnetic resonance spectrometer 10 is a three-dimensional spectrum, and the three dimensions are time, magnetic field intensity, and paramagnetic signal intensity.

[0056] Therefore, the electron paramagnetic resonance spectrometer 10 is provided to include: a laser system 100, which is used to emit laser to a probe containing an object to be detected; a magnetic field system 200, which is used to emit a magnetic field to the probe; a microwave system 300, which includes a microwave generating module 301, a mixing module 302 and a control module 303, wherein the microwave generating module 301 is connected to the mixing module 302, and is used to generate a first microwave signal and a second microwave signal, and emit microwaves to the probe according to the first microwave signal, and output the second microwave signal to the mixing module 302, the mixing module 302 is used to obtain a third microwave signal, and obtain a mixing signal according to the second microwave signal and the third microwave signal, the control module 303 is connected to the microwave generating module 301 and the mixing module 302, and is used to control the microwave generating module 301 according to the mixing signal to maintain the frequency of the first microwave signal at the resonant frequency, wherein the third microwave signal is a signal obtained according to the microwave after being acted on by the object to be detected; and an acquisition system 400, which is connected to the mixing module 302, and is used to acquire the mixing signal, and obtain an electron paramagnetic resonance detection result according to the mixing signal. Through the above settings, the control module 303 in the microblog system can be used to maintain the frequency of the first microwave signal generated by the microwave generation module 301 at the resonant frequency, thereby achieving better electron paramagnetic resonance detection. In addition, in order to support the improvement of the time resolution of signal processing, the modulation frequency is abandoned, thereby avoiding the problem that the transient signal cannot be modulated and demodulated due to the low modulation frequency.

[0057] Normally, in order to maintain the stability of the microwave signal frequency, a digital wave source based on direct digital synthesis technology is used. However, the output obtained by direct digital synthesis will have spurious signals. Normally, the spurious signal problem needs to be solved by modulating the frequency. However, in order to support the improvement of the time resolution of signal processing, the modulation frequency is cancelled in the present application. However, after the modulation frequency is cancelled, the problem of spurious signals of the digital wave source needs to be solved. Therefore, the present application adopts a solid-state microwave source, and sets the microwave frequency of the microwave system 300 to always be consistent with the resonant frequency of the probe, that is, by adopting a solid-state microwave source, and setting the microwave frequency to be consistent with the resonant frequency to ensure the stability of the microwave frequency, spurious signals are avoided. Moreover, since the microwave frequency is always consistent with the resonant frequency of the probe, the frequency tracking response is sensitive, which can meet the nanometer-level time resolution of transient electron paramagnetic resonance detection.

[0058] In some embodiments of the present invention, the laser system 100 includes a controller and a laser, and the laser is used to emit induction light or excitation light to the probe under the control of the controller.

[0059] In some embodiments of the present invention, the electron paramagnetic resonance spectrometer 10 further includes: a trigger system, which is connected to the acquisition system 400 and is used to generate a trigger signal when it is detected that the laser system 100 emits a laser, so as to trigger the acquisition system 400 to collect signals.

[0060] Specifically, in order to accurately collect the mixing signal when the laser system 100 emits the laser, the electron paramagnetic resonance spectrometer 10 is configured to further include a trigger system, and the trigger system is configured to be connected to the acquisition system 400. The trigger system can detect whether the laser system 100 emits the laser, and when it is detected that the laser system 100 emits the laser, the acquisition system 400 is triggered to collect the signal.

[0061] In some embodiments of the present invention, the acquisition system 400 includes an acquisition card, which is used to acquire mixed signals. The trigger system includes a photosensitive diode and a trigger, and the trigger is connected to the photosensitive diode and the acquisition card; wherein the photosensitive diode is located on a first optical path, and is used to generate an electrical signal when irradiated by a laser, and the first optical path is the optical path of the laser emitted by the laser system 100; the trigger is used to generate a trigger signal when receiving the electrical signal generated by the photosensitive diode, and send the trigger signal to the acquisition card, so that the acquisition card acquires the mixed signal under the triggering of the trigger signal.

[0062] Specifically, see Figure 4 In the example shown, the trigger system includes a photodiode and a trigger. The photodiode is located in the optical path of the laser emitted by the laser in the laser system 100. At this time, when the laser emits laser to the illumination hole in the probe, the photodiode will be illuminated by the laser emitted by the laser, thereby generating an electrical signal, so that the trigger triggers the acquisition card to collect signals and obtain a mixed signal.

[0063] Therefore, a trigger system is set up including a photodiode and a trigger. When the laser irradiates the photodiode, the photodiode generates an electrical signal, which is transmitted to the trigger, and the trigger sends a signal acquisition instruction to the acquisition card. The reason for setting a trigger between the photodiode and the acquisition card is that the photodiode has different electrical signal response levels to lasers of different wavelengths, but the voltage range of the acquisition instruction signal that the acquisition card can accept is narrow. Therefore, setting a trigger can trigger a larger range of response electrical signals of the photodiode, thereby issuing an acquisition instruction, which is conducive to expanding the applicable wavelength range of the laser.

[0064] For specific trigger acquisition timing diagram, please refer to Figure 5 ,exist Figure 5 In the figure, Laser is the timing of laser operation, Trigger is the trigger signal timing, and DAQ is the signal acquisition timing of the acquisition card.

[0065] In some embodiments of the present invention, the acquisition system 400 includes an acquisition card, which is used to acquire mixed signals. The trigger system includes a beam splitter, a photosensitive diode and a trigger, and the trigger is connected to the photosensitive diode and the acquisition card; wherein the beam splitter is located on the second optical path, and is used to split the laser on the second optical path into laser on a third optical path and laser on a fourth optical path. The second optical path is the optical path of the laser emitted by the laser system 100, the third optical path is the optical path from the beam splitter to the photosensitive diode, and the fourth optical path is the optical path from the beam splitter to the probe; the photosensitive diode is used to generate an electrical signal when irradiated by the laser; the trigger is used to generate a trigger signal when receiving the electrical signal generated by the photosensitive diode, and send the trigger signal to the acquisition card, so that the acquisition card acquires the mixed signal under the trigger of the trigger signal.

[0066] Specifically, see Figure 6 The example shown in Figure 6 In the embodiment, the trigger system includes not only a photodiode and a trigger, but also a beam splitter. When the laser in the laser system 100 emits laser light, the laser light first hits the beam splitter, and the beam splitter splits the laser light into two beams. The two beams of laser light are emitted to the illumination hole of the probe and the photodiode.

[0067] Therefore, by setting Figure 6 The trigger system shown can achieve Figure 4 The trigger system shown has a better ability to control the power of the laser incident on the probe, thereby achieving better electron paramagnetic resonance detection.

[0068] In some embodiments of the present invention, the microwave generating module 301 includes: a solid-state microwave source for generating a first microwave signal; a directional coupler connected to the circulator, the attenuator and the solid-state microwave source, for outputting the first microwave signal to the circulator and the attenuator; the circulator is used to input the first microwave signal into the probe; the attenuator is used to attenuate the first microwave signal; a phase shifter connected to the attenuator, for performing phase shift processing on the attenuated first microwave signal to obtain a second microwave signal, and output the second microwave signal to the mixing module 302.

[0069] In some embodiments of the present invention, the circulator is further used to obtain a third microwave signal and output the third microwave signal to the frequency mixing module 302 .

[0070] In some embodiments of the present invention, the mixing module 302 is specifically used to: obtain a fourth microwave signal and a fifth microwave signal according to the third microwave signal, multiply the fourth microwave signal by the second microwave signal, and perform low-pass filtering on the multiplication result to obtain a first mixing signal; and multiply the fifth microwave signal by the second microwave signal, and perform low-pass filtering on the multiplication result to obtain a second mixing signal, wherein the fourth microwave signal has the same phase as the third microwave signal, and there is a 90-degree phase difference between the fifth microwave signal and the third microwave signal.

[0071] In some embodiments of the present invention, the mixing module 302 is further used to obtain the first mixing signal and the second mixing signal according to the following formula:

[0072]

[0073] Where I(t) is the first mixing signal, Q(t) is the second mixing signal, V s is the voltage amplitude of the second microwave signal, is the phase of the second microwave signal, V r is the voltage amplitude of the third microwave signal, is the phase of the third microwave signal.

[0074] In some embodiments of the present invention, the fourth microwave signal and the fifth microwave signal are obtained according to the following formula:

[0075]

[0076] Wherein, I is the fourth microwave signal, Q is the fifth microwave signal, V r is the voltage amplitude of the third microwave signal, ω r is the frequency of the third microwave signal, is the phase of the third microwave signal, and t is the time.

[0077] In some embodiments of the present invention, the control module 303 is specifically used to: when the phases of the second microwave signal and the third microwave signal are the same, control the microwave generating module to adjust the frequencies of the first microwave signal and the second microwave signal according to the second mixing signal; or, when the phase difference between the second microwave signal and the third microwave signal is 90°, control the microwave generating module to adjust the frequencies of the first microwave signal and the second microwave signal according to the first mixing signal.

[0078] Specifically, a control module 303 may be provided to control the microwave generating module to increase the frequencies of the first microwave signal and the second microwave signal when the phase of the second microwave signal is the same as the phase of the third microwave signal and the second mixing signal is greater than zero; to control the microwave generating module to reduce the frequencies of the first microwave signal and the second microwave signal when the phase of the second microwave signal is the same as the phase of the third microwave signal and the second mixing signal is less than zero; or, to control the microwave generating module to increase the frequencies of the first microwave signal and the second microwave signal when the phase of the second microwave signal differs by 90 degrees from the phase of the third microwave signal and the first mixing signal is greater than zero; to control the microwave generating module to reduce the frequencies of the first microwave signal and the second microwave signal when the phase of the second microwave signal differs by 90 degrees from the phase of the third microwave signal and the first mixing signal is less than zero.

[0079] The following is an explanation with a specific example.

[0080] In this example, see Figure 7 The electron paramagnetic resonance spectrometer 10 includes a controller, a laser, a magnetic field mechanism, a probe, a photodiode, a trigger, an acquisition card, a solid-state microwave source, a directional coupler, an attenuator, a phase shifter, a circulator, a mixer and an automatic frequency control.

[0081] Specifically, Figure 7 The working principle of the electron paramagnetic resonance spectrometer 10 in the embodiment is:

[0082] The solid-state microwave source generates the first microwave signal, which is divided into two paths by a directional coupler:

[0083] One way through the attenuator and phase shifter reaches the mixer (that is, the second microwave signal mentioned above, hereinafter referred to as signal 1), signal 1 is:

[0084]

[0085] The other path enters the probe through the circulator, interacts with the object to be detected in the excited triplet state in the probe, is captured by the circulator, and enters the mixer (that is, the third microwave signal mentioned above, hereinafter referred to as signal 2); and after signal 2 enters the mixer, it is divided into two signals: I signal (a signal with the same phase as signal 2, that is, the fourth microwave signal mentioned above) and Q signal (a signal with a phase difference of 90° with signal 2, that is, the fifth microwave signal mentioned above);

[0086]

[0087] Among them, the above-mentioned I is the I signal, and the above-mentioned Q is the Q signal.

[0088] In the mixer, the I signal is multiplied by the 1 signal to obtain:

[0089]

[0090] In the mixer, the Q signal is multiplied by the signal 1 to obtain:

[0091]

[0092] In the above formula, Vs is the voltage amplitude of signal 1, Vr is the voltage amplitude of signal 2, ω 0 is the angular frequency of signal 1, is the phase of signal 1, ω r is the angular frequency of signal 2, is the phase of signal 2, and t is time. That is to say, the above-mentioned obtaining of the I signal and the Q signal according to signal 2 may be to obtain the amplitude, frequency and phase of signal 2, and obtain the above-mentioned I signal and Q signal according to the above-mentioned formula of the I signal and Q signal based on the amplitude, frequency and phase of signal 2; or may be to process signal 2 to obtain the above-mentioned I signal or Q signal, and then generate another signal based on the obtained signal.

[0093] Since the frequencies of signal 1 and signal 2 are the same, that is, ω 0 With ω r Therefore, after passing through the low-pass filter, the high-frequency AC component is filtered out and the following two equations are obtained:

[0094]

[0095] Among them, I(t) is the result after I1(t) passes through a low-pass filter, that is, the above-mentioned first mixing signal, and Q(t) is the result after Q1(t) passes through a low-pass filter, that is, the above-mentioned second mixing signal.

[0096] Since the voltage amplitude Vs of signal 1 is constant, according to the above two equations, the voltage amplitude fluctuation of signal 2 can be obtained, which is the paramagnetic signal generated by the transition absorption of the object to be detected.

[0097] The attenuator on the signal 1 path is used to adjust the strength of signal 1 so that it can better match the strength of signal 2 entering the mixer and improve the mixing effect; the phase shifter on the signal 1 path is used to adjust the phase of signal 1 so that the phase difference between signal 1 and signal 2 when entering the mixer is the preset value required by the system.

[0098] The signals output by the mixer include the above-mentioned I(t) and Q(t); the phase of signal 1 is adjusted by the phase shifter to maximize the value of Q(t) or I(t), for example: and The same, then:

[0099]

[0100] At this time, the value of I(t) is The value of Q(t) is 0. When the frequency of the microwave generated by the solid-state microwave source is detuned from the resonant frequency of the resonant cavity of the probe, the intensity of the Q signal will change as follows: Figure 8 The changes shown, i.e., the sign and magnitude of the Q(t) value, can indicate whether the microwave frequency deviates from the resonant frequency of the resonant cavity, and whether the microwave frequency is greater than or less than the resonant frequency of the resonant cavity.

[0101] Similarly, and The difference is 90°, then the value of Q(t) is The value of I(t) is 0; the sign and magnitude of the value of I(t) can be used to indicate whether the microwave frequency deviates from the resonant frequency of the resonant cavity, and whether the microwave frequency is greater than or less than the resonant frequency of the resonant cavity.

[0102] When the automatic frequency control system detects that the Q signal or I signal is not 0, it will send a control signal to the solid-state microwave source according to the specific value of the Q signal or I signal. The device that outputs microwave frequency from the solid-state microwave source is a voltage-controlled device. After receiving the control signal from the automatic frequency control system, it will adjust the wave source frequency control voltage according to the signal, thereby adjusting the microwave frequency output by the solid-state microwave source to make it consistent with the resonant frequency in the probe.

[0103] Therefore, through this control, it can be achieved that the frequency of the microwaves output by the solid-state microwave source is consistent with the resonant frequency in the probe.

[0104] Specifically, see Figure 8 ,when and When the solid-state microwave source has the same frequency as the first microwave signal and Q(t) is greater than zero, the frequency of the microwave generated by the solid-state microwave source is controlled to be increased, thereby increasing the frequencies of the first microwave signal and the second microwave signal.

[0105] when and When the solid-state microwave source has the same frequency as the first microwave signal and Q(t) is less than zero, the frequency of the microwave generated by the solid-state microwave source is controlled to be reduced, thereby reducing the frequencies of the first microwave signal and the second microwave signal.

[0106] Or, when and When the phase difference is 90 degrees and I(t) is greater than zero, the frequency of the microwaves generated by the solid-state microwave source is controlled to be increased, thereby increasing the frequencies of the first microwave signal and the second microwave signal.

[0107] when and When the phase difference is 90 degrees and I(t) is less than zero, the frequency of the microwaves generated by the solid-state microwave source is controlled to be reduced, thereby reducing the frequencies of the first microwave signal and the second microwave signal.

[0108] That is to say, only one of I(t) and Q(t) needs to be used.

[0109] Moreover, each time the acquisition card is triggered by the trigger, it collects the above I(t) and Q(t), obtains the paramagnetic signal strength according to I(t) and Q(t), and uses the paramagnetic signal strength as the electron paramagnetic resonance detection result.

[0110] In summary, the electron paramagnetic resonance spectrometer of the embodiment of the present invention includes: a laser system, which is used to emit laser to a probe containing an object to be detected; a magnetic field system, which is used to emit a magnetic field to the probe; a microwave system, which includes a microwave generating module, a mixing module and a control module, wherein the microwave generating module is connected to the mixing module, and is used to generate a first microwave signal and a second microwave signal, and emit microwaves to the probe according to the first microwave signal, and output the second microwave signal to the mixing module, the mixing module is used to obtain a third microwave signal, and obtain a mixing signal according to the second microwave signal and the third microwave signal, the control module is connected to the microwave generating module and the mixing module, and is used to control the microwave generating module according to the mixing signal to make the frequencies of the first microwave signal and the second microwave signal the same as the resonant frequency in the probe, wherein the third microwave signal is a signal obtained according to the microwave acting on the object to be detected; an acquisition system, which is connected to the mixing module, and is used to acquire the mixing signal, and obtain an electron paramagnetic resonance detection result according to the mixing signal. Therefore, a controller is used to send a control signal to the laser, and after receiving the control signal, the laser emits laser light into the probe, a photodiode is set to detect the laser light, and the detected signal is sent to the acquisition card as an acquisition trigger signal, thereby improving the time resolution of the electron paramagnetic resonance spectrometer signal acquisition. In addition, the use of a solid-state microwave source can further meet the nanometer-level time resolution of transient electron paramagnetic resonance detection.

[0111] Furthermore, the present invention proposes a transient electron paramagnetic resonance spectroscopy detection method.

[0112] Fig. 9 It is a flow chart of a transient electron paramagnetic resonance spectroscopy detection method according to an embodiment of the present invention.

[0113] In the embodiment of the present invention, the transient electron paramagnetic resonance spectroscopy detection method is applied to the electron paramagnetic resonance spectrometer 10 of the above embodiment.

[0114] like Fig. 9 As shown, the transient electron paramagnetic resonance spectroscopy detection method comprises:

[0115] S91, the acquisition system acquires N acquisition units.

[0116] Each acquisition unit is a unit obtained by the acquisition system performing n data acquisitions, where n is a positive integer greater than 1, and N is a positive integer greater than 1.

[0117] S92, adjusting the magnetic field provided for the probe, and returning to the step of acquiring N acquisition units by the acquisition system, until the number of times the magnetic field is adjusted reaches a preset number.

[0118] S93, obtaining a three-dimensional map including time, magnetic field strength, and paramagnetic signal strength according to the acquisition unit, and using the three-dimensional map as a detection result.

[0119] In one embodiment of the present invention, before adjusting the magnetic field provided to the probe, the transient electron paramagnetic resonance spectroscopy detection method further includes: averaging N acquisition units acquired by the acquisition system, and obtaining the paramagnetic signal intensity according to the average value.

[0120] The transient electron paramagnetic resonance spectroscopy detection method of the embodiment of the present invention uses the electron paramagnetic resonance spectrometer of the above embodiment, adopts a controller to send a control signal to the laser, and the laser emits laser into the probe after receiving the control signal, and a photosensitive diode is set to detect the laser, and the detected signal is sent to the acquisition card as an acquisition trigger signal, thereby improving the time resolution of the electron paramagnetic resonance spectrometer signal acquisition.

[0121] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0122] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0123] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0124] In the description of this specification, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as a limitation on the present invention.

[0125] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0126] In the description of this specification, unless otherwise specified, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0127] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0128] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. An electron paramagnetic resonance spectrometer, characterized in that include: A laser system for emitting laser light toward a probe containing an object to be detected; A magnetic field system, used for providing a magnetic field for the probe; A microwave system, comprising a microwave generating module, a frequency mixing module and a control module, wherein the microwave generating module is used to generate a first microwave signal and a second microwave signal, the first microwave signal is input into the probe to generate a third microwave signal, the frequency mixing module obtains a frequency mixing signal according to the second microwave signal and the third microwave signal, and the control module is used to control the microwave generating module according to the frequency mixing signal so that the frequencies of the first microwave signal and the second microwave signal are the same as the resonant frequency in the probe; The acquisition system is used to acquire the mixed signal according to the trigger signal generated by the laser, and obtain the electron paramagnetic resonance detection result according to the mixed signal.

2. The electron paramagnetic resonance spectrometer according to claim 1, characterized in that: The laser system comprises a controller and a laser, wherein the laser is used to emit induction light or excitation light to the probe under the control of the controller.

3. The electron paramagnetic resonance spectrometer according to claim 1, characterized in that: Also includes: A trigger system is connected to the acquisition system and is used to generate the trigger signal when detecting that the laser system emits laser, so as to trigger the acquisition system to perform signal acquisition.

4. The electron paramagnetic resonance spectrometer according to claim 3, characterized in that: The acquisition system includes an acquisition card, and the acquisition card is used to acquire the mixed signal. The trigger system includes a photosensitive diode and a trigger, and the trigger is connected to the photosensitive diode and the acquisition card; The photodiode is located on a first optical path and is used to generate an electrical signal when irradiated by laser light. The first optical path is the optical path of the laser emitted by the laser system. The trigger is used to generate the trigger signal when receiving the electrical signal generated by the photosensitive diode, and send the trigger signal to the acquisition card, so that the acquisition card acquires the mixed signal under the triggering of the trigger signal.

5. The electron paramagnetic resonance spectrometer according to claim 3, characterized in that: The acquisition system includes an acquisition card, and the acquisition card is used to acquire the mixed signal. The trigger system includes a beam splitter, a photosensitive diode and a trigger, and the trigger is connected to the photosensitive diode and the acquisition card; The beam splitter is located on the second optical path, and is used to split the laser on the second optical path into laser on a third optical path and laser on a fourth optical path, the second optical path is the optical path of the laser emitted by the laser system, the third optical path is the optical path from the beam splitter to the photodiode, and the fourth optical path is the optical path from the beam splitter to the probe; The photodiode is used to generate an electrical signal when irradiated by laser; The trigger is used to generate a trigger signal when receiving the electrical signal generated by the photosensitive diode, and send the trigger signal to the acquisition card, so that the acquisition card acquires the mixed signal under the triggering of the trigger signal.

6. The electron paramagnetic resonance spectrometer according to claim 1, characterized in that: The microwave generating module comprises: a solid-state microwave source, configured to generate the first microwave signal; a directional coupler connected to the circulator, the attenuator and the solid-state microwave source, and configured to output the first microwave signal to the circulator and the attenuator; The circulator is used to input the first microwave signal into the probe; The attenuator is used to attenuate the first microwave signal; A phase shifter is connected to the attenuator and is used for performing phase shift processing on the attenuated first microwave signal to obtain the second microwave signal, and outputting the second microwave signal to the mixing module.

7. The electron paramagnetic resonance spectrometer according to claim 6, characterized in that: The circulator is further used to obtain the third microwave signal and output the third microwave signal to the frequency mixing module.

8. The electron paramagnetic resonance spectrometer according to claim 6, characterized in that: The frequency mixing module is specifically used for: A fourth microwave signal and a fifth microwave signal are obtained according to the third microwave signal, and the fourth microwave signal is multiplied by the second microwave signal, and the multiplication result is low-pass filtered to obtain a first mixing signal; and the fifth microwave signal is multiplied by the second microwave signal, and the multiplication result is low-pass filtered to obtain a second mixing signal, wherein the fourth microwave signal has the same phase as the third microwave signal, and the fifth microwave signal has a 90 degree phase difference with the third microwave signal.

9. The electron paramagnetic resonance spectrometer according to claim 8, characterized in that: The mixing module is further used for: The first mixing signal and the second mixing signal are obtained according to the following formula: Wherein, I(t) is the first mixing signal, Q(t) is the second mixing signal, V s is the voltage amplitude of the second microwave signal, is the phase of the second microwave signal, V r is the voltage amplitude of the third microwave signal, is the phase of the third microwave signal.

10. The electron paramagnetic resonance spectrometer according to claim 9, characterized in that: The control module is specifically used for: When the phases of the second microwave signal and the third microwave signal are the same, controlling the microwave generating module to adjust the frequencies of the first microwave signal and the second microwave signal according to the second mixing signal; Alternatively, when the phase difference between the second microwave signal and the third microwave signal is 90°, the microwave generating module is controlled to adjust the frequencies of the first microwave signal and the second microwave signal according to the first mixing signal.

11. The electron paramagnetic resonance spectrometer according to claim 10, characterized in that: The control module is specifically used for: When the phase of the second microwave signal is the same as the phase of the third microwave signal and the second mixing signal is greater than zero, controlling the microwave generating module to increase the frequencies of the first microwave signal and the second microwave signal; When the phase of the second microwave signal is the same as the phase of the third microwave signal and the second mixing signal is less than zero, controlling the microwave generating module to reduce the frequencies of the first microwave signal and the second microwave signal; or, When the phase of the second microwave signal differs from the phase of the third microwave signal by 90 degrees and the first mixing signal is greater than zero, controlling the microwave generating module to increase the frequencies of the first microwave signal and the second microwave signal; When the phase of the second microwave signal differs from the phase of the third microwave signal by 90 degrees and the first mixing signal is less than zero, the microwave generating module is controlled to reduce the frequencies of the first microwave signal and the second microwave signal.

12. A transient electron paramagnetic resonance spectroscopy detection method, characterized in that: Applied to the electron paramagnetic resonance spectrometer according to any one of claims 1 to 11; the method comprises: The acquisition system acquires N acquisition units, wherein each of the acquisition units is a unit acquired by the acquisition system performing n data acquisitions, n is a positive integer greater than 1, and N is a positive integer greater than 1; Adjusting the magnetic field provided for the probe, and returning to the step of acquiring N acquisition units by the acquisition system until the number of times the magnetic field is adjusted reaches a preset number; A three-dimensional map including time, magnetic field strength, and paramagnetic signal strength is obtained according to the acquisition unit, and the three-dimensional map is used as a detection result.

13. The transient electron paramagnetic resonance spectroscopy detection method according to claim 12, characterized in that: Before adjusting the magnetic field provided to the probe, the method further includes: The N acquisition units acquired by the acquisition system are averaged, and the paramagnetic signal strength is obtained according to the average value.

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