Nuclear magnetic resonance is mainly caused by the spin motion of the nucleus. Different nuclei have different spin motions, which can be expressed by the spin quantum number I of the nucleus. The spin quantum number is related to the atomic mass number and atomic number.

Nuclei are positively charged particles. Nuclei that cannot spin have no magnetic moment. The spinning nucleus has a circulating current, which will generate a magnetic field and form a magnetic moment (μ). When the spin core is in an external magnetic field with a magnetic induction of B0, it will move around B0 in addition to the spin, which is very similar to the movement of the gyro, and is called larmorprocess.

The angular velocity ω0 of the precession of the spin nucleus is directly proportional to the induction intensity B0 of the external magnetic field, and the proportional constant is the magnetization ratio γ. Where ν0 is the precession frequency.

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Extended data:

The principle of nuclear magnetic resonance is mainly caused by the spin motion of the nucleus. Different nuclei have different spin motions, which can be expressed by the spin quantum number I of the nucleus.

An imaging of the observed H proton movement in the human body. During the inspection, the examinee will be in a large magnet, that is, a large cylinder. Through the excitation of radio frequency, H protons in different organs in the human body will have different activities.

The generated RF pulse is absorbed by the coil to produce an image, so the imaging of magnetic resonance is actually the imaging of H protons in the human body. Patients with cardiac pacemakers, patients with fever and patients with plaster are forbidden to do magnetic resonance imaging.

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