A high-sensitivity continuous wave paramagnetic resonance spectrometer probe

Abstract

The present invention discloses a high-sensitivity continuous wave paramagnetic resonance spectrometer probe, comprising a resonant cavity and a microwave coupling structure and a high-frequency modulation magnetic field coupling structure arranged on the resonant cavity, wherein the resonant cavity adopts a cylindrical cavity, the microwave coupling structure is a first small hole arranged on the waveguide access side of the cylindrical cavity, and the high-frequency modulation magnetic field coupling structure comprises a plurality of thin-walled copper tubes vertically penetrating the cylindrical cavity and distributed at equal intervals, and a Helmholtz coil is wound inside the thin-walled copper tube. The present invention adopts a cylindrical cavity with a high Q value, increases the sensitivity of system detection, increases the sample area, and has a larger functional expansion space; and realizes high-efficiency high-frequency modulation magnetic field coupling through the thin-walled copper tube.

Description

Technical Field

[0001] The invention relates to the technical field of electron paramagnetic resonance, in particular to a high-sensitivity continuous wave paramagnetic resonance spectrometer probe. Background Art

[0002] Electron paramagnetic resonance (EPR) is a magnetic resonance technique originated from the magnetic moment of unpaired electrons. It can be used to detect the unpaired electrons contained in atoms or molecules of substances from qualitative and quantitative aspects, and explore the structural characteristics of their surroundings. Electron paramagnetic resonance spectrometers are mainly divided into two types: pulsed type and continuous wave type. Continuous wave paramagnetic resonance spectrometers obtain continuous wave EPR spectral lines by placing the sample to be tested in a microwave field of constant frequency and changing the frequency of the external magnetic field.

[0003] In electron paramagnetic resonance experiments, resonant cavities play an important role. Different forms of resonant cavities have been developed according to different experimental requirements. Commonly used ones include rectangular cavities, cylindrical cavities, dielectric cavities, slit cavities, etc. Rectangular cavities are often used in continuous wave electron paramagnetic resonance experiments, but their Q value is low and it is difficult to apply them to some low-sensitivity material detection; cylindrical cavities have very high Q values ​​and are well used in some special applications (such as low-temperature experiments); slit cavities have a high filling factor, but their Q value is low, which is more suitable for pulsed electron paramagnetic resonance experiments and rarely used in continuous wave electron paramagnetic resonance experiments.

[0004] In the continuous wave electron paramagnetic resonance experiment, the design requirements of the resonant cavity are: 1. When the system sensitivity requirement is high, the resonant cavity needs to have a high Q value; 2. Ensure that the direction of the magnetic field B1 is perpendicular to the direction of the external static magnetic field; 3. Ensure that the magnetic field B1 in the sample placement area is as large as possible; 4. Have high-frequency modulation field coupling capability to meet the needs of the high-frequency small modulation field detection method of the continuous wave paramagnetic resonance spectrometer.

[0005] The existing resonant cavity has the following problems when used in continuous wave paramagnetic resonance spectrometers: ⑴ Rectangular cavities are often used in continuous wave electron paramagnetic resonance experiments, but their Q value is low, making them difficult to use for some low-sensitivity material detection; ⑵ Continuous wave paramagnetic resonance spectrometers use high-frequency small field modulation technology, which requires a certain intensity of modulated magnetic field to be coupled into the resonant cavity, and the coupling ability of existing coupling structures is poor; ⑶ The sample area is small and the expandability is weak. Summary of the invention

[0006] In view of the technical problems existing in the existing resonant cavity in the application of continuous wave paramagnetic resonance spectrometer, the present invention provides a high-sensitivity continuous wave paramagnetic resonance spectrometer probe with strong high-frequency modulation magnetic field coupling function.

[0007] A high-sensitivity continuous wave paramagnetic resonance spectrometer probe comprises a resonant cavity and a microwave coupling structure and a high-frequency modulated magnetic field coupling structure arranged on the resonant cavity. The resonant cavity adopts a cylindrical cavity. The microwave coupling structure is a first small hole arranged on the waveguide access side of the cylindrical cavity. The high-frequency modulated magnetic field coupling structure comprises a plurality of thin-walled copper tubes vertically penetrating the cylindrical cavity and distributed at equal intervals, and a Helmholtz coil is wound inside the thin-walled copper tube.

[0008] Furthermore, the cylindrical cavity has a split structure, consisting of a cylindrical main cavity with an inner circle and an outer square, an external signal source access cavity arranged at the bottom of the cylindrical main cavity, and a cover plate arranged at the top of the cylindrical main cavity. The thin-walled copper tube is fixed to the cylindrical main cavity by a limiting column.

[0009] Furthermore, a second small hole for introducing light is provided on the side of the cylindrical main cavity opposite to the first small hole, and a light source mounting structure is embedded and fixed therein.

[0010] Furthermore, an aviation socket for accessing an external signal source is fixed on the side of the external signal source access cavity opposite to the first small hole.

[0011] Furthermore, a sample placement cavity is vertically provided in the middle of the cylindrical cavity, and two ends of the sample placement cavity extend out of the cylindrical cavity and are provided with a clamp for clamping the test sample.

[0012] Furthermore, the first small hole is a waist hole arranged parallel to the thin-walled copper tube, and a tuning unit is provided on the side of the first small hole of the cylindrical cavity. The tuning unit consists of a tuning screw and a tuning block fixed to the end of the tuning screw. The tuning screw slides up and down relative to the first small hole under the drive of an external driving mechanism.

[0013] Furthermore, a tuning screw accommodating cavity is provided on the outside of the cylindrical main cavity, and the tuning screw accommodating cavity is connected to the waveguide; preferably, the tuning screw accommodating cavity and the cylindrical main cavity are an integrated structure.

[0014] The beneficial effects of the present invention are as follows: 1. The resonant cavity adopts a cylindrical cavity with a high Q value, which increases the sensitivity of system detection and increases the sample area, so that it has a larger functional expansion space; 2. High-frequency modulation magnetic field coupling with higher efficiency is achieved through thin-walled copper tubes; 3. The split cylindrical cavity is easy to disassemble and assemble. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the probe explosion;

[0016] Figure 2 It is a three-dimensional diagram of the main cylindrical cavity;

[0017] Figure 3It is a side view of the cylindrical main cavity;

[0018] Figure 4 for Figure 3 AA surface section view in;

[0019] Figure 5 It is a schematic diagram of the fixing groove at the bottom of the cylindrical main cavity;

[0020] Figure 6 This is a stereogram of the external connections of the probe;

[0021] Figure 7 This is the side view of the probe's external connections;

[0022] Figure 8 for Figure 7 BB surface section view in. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

[0024] Example 1

[0025] A high-sensitivity continuous wave paramagnetic resonance spectrometer probe, such as Figure 1-8 As shown, it includes a resonant cavity 1 and a microwave coupling structure and a high-frequency modulated magnetic field coupling structure arranged on the resonant cavity. The microwave signal is coupled into the resonant cavity through the microwave coupling structure, and the external high-frequency modulated magnetic field is coupled into the resonant cavity through the high-frequency modulated magnetic field coupling structure.

[0026] The resonant cavity 1 adopts a cylindrical cavity with a high Q value to increase the sensitivity of the system detection. The microwave coupling structure is a first small hole 2 arranged on the waveguide access side of the cylindrical cavity. The high-frequency modulation magnetic field coupling structure includes a plurality of thin-walled copper tubes 3 vertically penetrating the cylindrical cavity and distributed at equal intervals, and a Helmholtz coil is wound inside the thin-walled copper tube 3. The Helmholtz coil couples the modulated magnetic field into the resonant cavity through the thin-walled copper tube, and the modulation field coupling efficiency is high.

[0027] In order to facilitate disassembly and assembly, the cylindrical cavity is a split structure, consisting of a cylindrical main cavity 101 with an inner circle and an outer square, an external signal source access cavity 102 arranged at the bottom of the cylindrical main cavity, and a cover plate 103 arranged at the top of the cylindrical main cavity. The thin-walled copper tube 3 is fixed on the cylindrical main cavity 101 by a limiting column 4. Figure 1 The bottom of the cover plate and the bottom of the cylindrical main cavity are both provided with a limit column fixing groove 104 (refer to Figure 1 , Figure 5 ), the two ends of the thin-walled copper tube extend into the limit column fixing groove 104 respectively, and are fixed by the limit column 4. The cover plate, the external signal source access cavity and the cylindrical main cavity are detachably fixedly connected by bolts. The cylindrical main cavity has a round inner and square outer structural design, which provides a larger cylindrical cavity inside, which is convenient for the fixed installation of the thin-walled copper tube and the placement of the sample; the outside provides an expandable area of ​​at least 4 surfaces, which is also more convenient for the installation and fixation of other functional modules.

[0028] The cylindrical main cavity 101 is provided with a second small hole 5 for introducing light on the side opposite to the first small hole 2, and a light source mounting structure 6 is embedded and fixed therein. Figure 1 , Figure 2 .

[0029] An aviation socket 7 for connecting an external signal source is fixed on the side opposite to the first small hole of the external signal source access cavity 102. The external signal source is connected to the aviation socket 7 through an aviation plug, and a high-frequency modulation magnetic field is introduced, which is coupled into the resonant cavity 1 through a thin-walled copper tube with a Helmholtz coil wound inside.

[0030] A sample placement cavity 8 is vertically provided in the middle of the cylindrical cavity. Both ends of the sample placement cavity 8 extend out of the cylindrical cavity and are provided with a clamp 9 for clamping the test sample, so as to facilitate the placement and fixation of the sample.

[0031] The first small hole 2 is a waist hole arranged parallel to the thin-walled copper tube. Figure 3 A tuning unit 10 is provided on the side of the first small hole of the cylindrical cavity. The tuning unit is composed of a tuning screw and a tuning block (not shown in the figure) fixed to the end of the tuning screw. The tuning screw slides up and down relative to the first small hole under the drive of the external driving mechanism 14. The specific structure of the external driving mechanism to realize the screw-in depth of the tuning screw is disclosed in the utility model patent CN210389084U authorized and announced on April 24, 2020.

[0032] In order to accommodate the tuning unit, a tuning screw accommodating cavity 11 is provided outside the cylindrical main cavity, and the tuning screw accommodating cavity 11 is connected to the waveguide 12; preferably, the tuning screw accommodating cavity and the cylindrical main cavity are an integrated structure.

[0033] The waveguide 12 is fixed between the annular electromagnets on both sides by a non-magnetic mounting bracket, and the scheme is disclosed in the utility model CN211423816U authorized and announced on September 4, 2020. In this embodiment, the microwave application range is within the X-band, and the waveguide access unit is connected to the system through a coaxial interface, using a standard SMA interface.

[0034] The high-sensitivity continuous wave paramagnetic resonance spectrometer probe disclosed in the present invention has a cavity resonance frequency of 9-10 GHz, a minimum S11 of better than -30 dB, and a Q value of higher than 7000 at critical coupling. High-frequency modulation magnetic field coupling is performed through a thin-walled copper tube, and has a high coupling efficiency. The low-frequency magnetic field conversion efficiency is simulated to be 9.8 Gauss / A using ANSOFT's Maxwell software.

[0035] Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Those skilled in the art of the present invention may make various modifications or additions to the described specific embodiments or replace them in a similar manner, but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art and related fields without creative work shall fall within the scope of protection of the present invention.

Claims

1. A high-sensitivity continuous wave paramagnetic resonance spectrometer probe, comprising a resonant cavity and a microwave coupling structure and a high-frequency modulated magnetic field coupling structure arranged on the resonant cavity, characterized in that: The resonant cavity is a cylindrical cavity, the microwave coupling structure is a first small hole arranged on the waveguide access side of the cylindrical cavity, and the high-frequency modulated magnetic field coupling structure includes a plurality of thin-walled copper tubes vertically penetrating the cylindrical cavity and distributed at equal intervals, and a Helmholtz coil is wound inside the thin-walled copper tube.

2. The high-sensitivity continuous wave paramagnetic resonance spectrometer probe according to claim 1, characterized in that: The cylindrical cavity is a split structure, consisting of a cylindrical main cavity with an inner circle and an outer square, an external signal source access cavity arranged at the bottom of the cylindrical main cavity, and a cover plate arranged at the top of the cylindrical main cavity. The thin-walled copper tube is fixed to the cylindrical main cavity by a limiting column.

3. The high-sensitivity continuous wave paramagnetic resonance spectrometer probe according to claim 2, characterized in that: A second small hole for introducing light is provided on the side of the cylindrical main cavity opposite to the first small hole, and a light source mounting structure is embedded and fixed therein.

4. The high-sensitivity continuous wave paramagnetic resonance spectrometer probe according to claim 2, characterized in that: An aviation socket for accessing an external signal source is fixed on the side of the external signal source access cavity opposite to the first small hole.

5. The high-sensitivity continuous wave paramagnetic resonance spectrometer probe according to any one of claims 1 to 4, characterized in that: A sample placement cavity is vertically penetrated through the middle of the cylindrical cavity, and two ends of the sample placement cavity extend out of the cylindrical cavity and are provided with a clamp for clamping the test sample.

6. The high-sensitivity continuous wave paramagnetic resonance spectrometer probe according to claim 2, characterized in that: The first small hole is a waist hole arranged parallel to the thin-walled copper tube. A tuning unit is provided on the side of the first small hole of the cylindrical cavity. The tuning unit consists of a tuning screw and a tuning block fixed to the end of the tuning screw. The tuning screw slides up and down relative to the first small hole driven by an external driving mechanism.

7. The high-sensitivity continuous wave paramagnetic resonance spectrometer probe according to claim 6, characterized in that: A tuning screw accommodating cavity is provided outside the cylindrical main cavity, and the tuning screw accommodating cavity is connected to the waveguide.

8. The high-sensitivity continuous wave paramagnetic resonance spectrometer probe according to claim 7, characterized in that: The tuning screw accommodating cavity and the cylindrical main cavity are an integrated structure.

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