## An Attempt on the Teaching Basic Concepts of the Nuclear Magnetic Resonance

Ma Zhonghua, Cao Xiufang, Jiang Hong, Ma Jimei,

 基金资助: 华中农业大学一流课程课堂研究与改革项目.  2019055

Abstract

Nuclear magnetic resonance (NMR) is a frequently used spectral method for structural analysis of organic compounds. It is also an important content in the teaching of spectroscopy course. The principle of nuclear magnetic resonance involves some basic concepts including magnetic nucleus, nuclear spin, angular momentum, magnetogyric ratio, electric quadrupole moment, and the change of the internal nuclear energy level distribution in external magnetic field, etc. These concepts are important for the beginners to understand the principle of nuclear magnetic resonance. In this article, the attempt to rationally simplify the complex principle of quantum physics and elucidate the principle from the view of chemistry discipline, and to reasonably integrate ideological and political elements in teaching is discussed. This practice would not only help the students to understand the basic principle in depth, but also cultivate their scientific and systematical thinking and ability to solve complex problems.

Keywords： Nuclear magnetic resonance ; Magnetic nucleus ; Magnetogyric ratio ; Nuclear magnetic moment ; Angular momentum

Ma Zhonghua. An Attempt on the Teaching Basic Concepts of the Nuclear Magnetic Resonance. University Chemistry[J], 2021, 36(4): 2004004-0 doi:10.3866/PKU.DXHX202004004

### 1.2 教学中存在的问题与难点

#### 1.3 教学处理

 核的分类 同位素 自旋量子数(I) 核磁矩 电四极矩Q 图示 说明 非磁性核 4He 0 0 0 质子和中子数为偶数，所有核子均配对，总体没有磁效应 12C 0 0 0 磁性核 1H 1/2 2.79285 0 单个成单质子或者中子，原子核电荷分布均匀 13C 1/2 0.70241 0 17O 5/2 -1.8938 < 0 核子数为奇数，总体有磁效应。多个成单核子 2H(D) 1 0.85744 > 0 质子和中子数为奇数，有两个成单核子，总体有磁效应。I = (1/2 + 1/2) = 1 14N 1 +0.40376 > 0

#### 1.3.3 含多个成单核子的磁性核(奇奇核)

17O核涉及单核子自旋与轨道耦合引起的能级分裂，以及复杂的能级跃迁引起的质子重新分布[5]，也简化为用椭球型表示其电四极矩不为0。

### 图3

P = s + l代入，则μ = $\frac{\text{e}}{\text{2}{\text{m}}_{\text{I}}}$(P + s)。

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