阅读说明：本技术 一种微波谐振腔及使用它的电子顺磁共振探头 (Microwave resonant cavity and electron paramagnetic resonance probe using same ) 是由 苏陶 石致富 于 2019-11-05 设计创作，主要内容包括：本发明公开了一种微波谐振腔及使用它的电子顺磁共振探头,微波谐振腔包括竖直设置的环形蓝宝石晶体和套设于所述环形蓝宝石晶体外部的金属套筒,所述金属套筒上水平等间隔环设有多条缝隙；电子顺磁共振探头上述微波谐振腔、与所述微波谐振腔固定连接的调谐单元、位于所述调谐单元和所述微波谐振腔之间的耦合单元,所述微波谐振腔两侧设有亥姆赫兹线圈,所述亥姆赫兹线圈由水平固定的线圈固定机构和绕制于其上的漆包线线圈组成,所述线圈固定机构采用绝缘材料制成；所述微波谐振腔和所述亥姆赫兹线圈封闭于壳体内。本发明使用了特殊的调制场耦合结构,调制场耦合能力强,使调制场转化效率有较大提高。(The invention discloses a microwave resonant cavity and an electron paramagnetic resonance probe using the same, wherein the microwave resonant cavity comprises an annular sapphire crystal which is vertically arranged and a metal sleeve which is sleeved outside the annular sapphire crystal, and a plurality of gaps are annularly arranged on the metal sleeve at equal intervals; the electronic paramagnetic resonance probe comprises a microwave resonant cavity, a tuning unit fixedly connected with the microwave resonant cavity and a coupling unit positioned between the tuning unit and the microwave resonant cavity, wherein Helmholtz coils are arranged on two sides of the microwave resonant cavity and consist of a coil fixing mechanism fixed horizontally and an enameled wire coil wound on the coil fixing mechanism, and the coil fixing mechanism is made of insulating materials; the microwave resonant cavity and the Helmholtz coil are enclosed in a shell. The invention uses a special modulation field coupling structure, has strong modulation field coupling capability and greatly improves the modulation field conversion efficiency.)

1. The microwave resonant cavity is characterized by comprising a vertically arranged annular sapphire crystal and a metal sleeve sleeved outside the annular sapphire crystal, wherein a plurality of gaps are horizontally and equally spaced on the metal sleeve.

2. A microwave resonant cavity according to claim 1, wherein the annular sapphire crystal dimensions are 10mm outside diameter, 5mm inside diameter, and 13mm height; 10 gaps are formed in the metal sleeve, each gap is 0.18mm high, and the distance between every two adjacent gaps is 1 mm.

3. A microwave resonant cavity according to claim 1, wherein the annular sapphire crystal is fixed at both upper and lower ends thereof by a teflon spacer with a step therein, and the size of the step is matched with that of the annular sapphire crystal.

4. An electron paramagnetic resonance probe, which comprises the microwave resonant cavity according to claims 1 to 3, a tuning unit fixedly connected with the microwave resonant cavity, and a coupling unit located between the tuning unit and the microwave resonant cavity, wherein Helmholtz coils are arranged at two sides of the microwave resonant cavity, each Helmholtz coil consists of a horizontally fixed coil fixing mechanism and an enameled wire coil wound on the Helmholtz coil, and the coil fixing mechanism is made of an insulating material; the microwave resonant cavity and the Helmholtz coil are enclosed in a shell.

5. The electron paramagnetic resonance probe according to claim 4, wherein the enameled wire coil is made of enameled wire with a diameter of 0.51mm wound on the coil fixing mechanism for 110 turns.

6. The electron paramagnetic resonance probe of claim 4 or 5 wherein the tuning unit is a tuning screw and the coupling unit is a small hole coupling.

7. The electron paramagnetic resonance probe according to claim 6, wherein the microwave resonant cavity is fixed on a waveguide access plate, a coupling hole is vertically formed on one side of the waveguide access plate for fixing the microwave resonant cavity, and a waveguide port is formed on the other side of the waveguide access plate; the tuning screw is vertically inserted into the waveguide access plate and extends to the waveguide port.

8. The electron paramagnetic resonance probe according to claim 7, wherein the housing is composed of a waveguide access plate, an upper sealing plate, a lower sealing plate and a side sealing plate, and clamps for clamping a detection sample are arranged on the upper sealing plate and the lower sealing plate; during detection, a sample is vertically inserted into the microwave resonant cavity.

Technical Field

The invention relates to the technical field of electron paramagnetic resonance, in particular to a microwave resonant cavity with a low-frequency modulation magnetic field coupling function and an electron paramagnetic resonance probe using the microwave resonant cavity.

Background

Electron Paramagnetic Resonance (EPR) is a magnetic resonance technique that is derived from the magnetic moment of unpaired electrons, and can be used to qualitatively and quantitatively detect the unpaired electrons contained in substance atoms or molecules and to explore the structural characteristics of their surroundings.

In electron paramagnetic resonance experiments, resonant cavities play an important role. In order to meet different experimental requirements, resonant cavities also have different forms, and commonly used resonant cavities include rectangular cavities, cylindrical cavities, medium cavities, crack cavities and the like. The existing resonant cavity has the following problems: the rectangular cavity and the cylindrical cavity have high Q values, but EPR signals cannot be detected in some samples with extremely low sensitivity; the quality factor is low, the Q value is one of important factors for determining the EPR signal intensity, the crack cavity filling factor is high, but the Q value is low, and the resonant cavity is rarely used in a continuous wave electron paramagnetic resonance experiment; the coupling structure has single function, the conventional resonant cavity focuses on critical coupling, the application of the resonant cavity in an over-coupling state is often ignored, and the low-Q-value resonant cavity can be used in some special applications, such as a pulse electron paramagnetic resonance spectrometer, under the over-coupling condition; fourth, the coupling capability of a low-frequency modulation field is poor, a phase-sensitive detection technology used in an electronic paramagnetic resonance spectrometer needs to couple a modulation magnetic field with certain intensity into a resonant cavity, and the coupling capability of an existing coupling structure is poor.

Disclosure of Invention

In view of the above problems, the present invention provides a microwave resonant cavity with a low-frequency modulation magnetic field coupling function and an electron paramagnetic resonance probe using the same.

The invention provides a microwave resonant cavity with low-frequency modulation field coupling capacity, which comprises an annular sapphire crystal and a metal sleeve, wherein the annular sapphire crystal is vertically arranged, the metal sleeve is sleeved outside the annular sapphire crystal, and a plurality of gaps are horizontally and annularly arranged on the metal sleeve at equal intervals.

Further, the size of the annular sapphire crystal is 10mm in outer diameter, 5mm in inner diameter and 13mm in height; 10 gaps are formed in the metal sleeve, each gap is 0.18mm high, and the distance between every two adjacent gaps is 1 mm.

Furthermore, the upper part and the lower part of the annular sapphire crystal are limited and fixed through a Teflon gasket with a step arranged inside, and the size of the step is matched with that of the annular sapphire crystal.

The invention also protects an electron paramagnetic resonance probe using the microwave resonant cavity, which comprises the microwave resonant cavity, a tuning unit fixedly connected with the microwave resonant cavity, and a coupling unit positioned between the tuning unit and the microwave resonant cavity, wherein Helmholtz coils are arranged at two sides of the microwave resonant cavity, each Helmholtz coil consists of a coil fixing mechanism which is horizontally fixed and an enameled wire coil wound on the coil fixing mechanism, and the coil fixing mechanism is made of insulating materials; the microwave resonant cavity and the Helmholtz coil are enclosed in a shell.

Further, the enameled wire coil is formed by winding an enameled wire with the diameter of 0.51mm on the coil fixing mechanism for 110 turns.

Furthermore, the tuning unit adopts a tuning screw, and the coupling unit adopts a small hole for coupling.

Further, the microwave resonant cavity is fixed on a waveguide access plate, one side of the waveguide access plate, which is used for fixing the microwave resonant cavity, is vertically provided with a coupling hole, and the other side of the waveguide access plate is provided with a waveguide port; the tuning screw is vertically inserted into the waveguide access plate and extends to the waveguide port.

Further, the shell consists of a waveguide access plate, an upper sealing plate, a lower sealing plate and side sealing plates, and clamps for clamping detection samples are arranged on the upper sealing plate and the lower sealing plate; during detection, a sample is vertically inserted into the microwave resonant cavity.

The microwave resonant cavity disclosed by the invention has the advantages that the Q value is higher, the filling factor is higher, the medium with smaller inner diameter is used, the filling factor is improved, the simulation of the filling factor reaches 13.15%, and the actual measurement of the Q value reaches 1232; the Q value is tunable, the optimized coupling structure size is used, the tuning of the Q value range is realized, the actually measured Q value can reach 171 to the minimum, and the method can be used for not only continuous wave EPR experiments but also pulse type EPR experiments; a special modulation field coupling structure is used, the modulation field coupling capability is strong, and the modulation field conversion efficiency is greatly improved; greatly meets the requirements of electron paramagnetic resonance experiments.

Drawings

FIG. 1 is a schematic diagram of a microwave resonant cavity structure;

FIG. 2 is a schematic view of a Teflon gasket;

FIG. 3 is a schematic diagram of the internal structure of the electron paramagnetic resonance probe;

FIG. 4 is a schematic view of a waveguide port on a waveguide access plate;

FIG. 5 is a schematic view of a coupling hole located on a waveguide access plate;

FIG. 6 is a diagram showing the state where the electron paramagnetic resonance probe is inserted into a sample;

FIG. 7 is a diagram of the waveguide input connection of the electron paramagnetic resonance probe;

FIG. 8 is a simulation diagram of microwave magnetic field distribution;

FIG. 9 is a simulation of low frequency modulated magnetic field distribution;

fig. 10 shows S11 for the case of critical coupling and overcoupling of the measured microwave cavity.

Detailed Description

The present invention will be described in further detail with reference to the following drawings and specific examples. The embodiments of the present invention have been presented for purposes of illustration and description, and are not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.