核自旋与乙烯分子的核自旋变体的分离和转换研究进展

发布时间：2018-05-18 08:38

本文选题：质子 + 中子　；参考：《物理学进展》2017年06期

【摘要】：原子核(简称核)由质子和中子构成,核内所有质子和中子的角动量之和通常称为核自旋。虽然核自旋变体及其稳定性是量子力学中的基本概念,而且由核自旋不为零的同种原子组成的所有分子都有两种或两种以上的核自旋变体,但对气相多原子分子核自旋变体的分离和相互转换动力学的研究,直到九十年代初才打破了沉寂了几十年的局面。十多年前乙烯分子的四种核自旋变体的分离和转换实验研究有了首次突破,本文对此做了重点介绍。文章按年代发展首先简要地综述了构成原子核的质子和中子发现的科学史,提出了核自旋变体的概念,详细描述了氢分子的两种核自旋变体(正氢和仲氢)以及乙烯分子的四种核自旋变体。然后着重介绍了利用光诱导漂移技术,对气相乙烯分子的核自旋变体的分离实验;用宇称守恒与量子弛豫理论定量地描述了核自旋变体间相互转换研究的进展。最后概述了通过仲氢对乙炔催化加氢的化学合成方法用来提高乙烯分子的核自旋变体浓度,足以增强其核磁共振信号强度的最新成果。
[Abstract]:The nucleus is composed of protons and neutrons. The sum of angular momentum of all protons and neutrons in the nucleus is usually called nuclear spin. Although nuclear spin variants and their stability are fundamental concepts in quantum mechanics, and all molecules consisting of the same atom with non-zero nuclear spin have two or more nuclear spin variants, However, the separation and interconversion kinetics of gas phase polyatomic molecular nuclear spins was not broken until the beginning of 1990s. The separation and conversion of four nuclear spin variants of ethylene molecules made the first breakthrough more than ten years ago. In this paper, the history of the discovery of protons and neutrons, which make up the nucleus, is first briefly reviewed, and the concept of the nuclear spin-variant is put forward. Two nuclear spin variants (normal hydrogen and secondary hydrogen) and four nuclear spin variants of ethylene molecule are described in detail. Then, the separation experiments of nuclear spin variants of gas phase ethylene molecules using photoinduced drift technique are introduced, and the progress in the study of the intertransformation between nuclear spin variants is described quantitatively by using parity conservation and quantum relaxation theory. In the end, the recent achievements of the chemical synthesis method of catalytic hydrogenation of acetylene from para-hydrogen to increase the concentration of nuclear spin variant of ethylene molecule are summarized, which are sufficient to enhance the nuclear magnetic resonance signal intensity of ethylene molecule.
【作者单位】：山东大学物理学院;喀什大学物理与电气工程学院;
【基金】：国家自然科学基金(91536105,11174186,11074147) “天山学者计划” 日本学术振兴会JSPS(P04063,L10519,BR161302)的资助
【分类号】：O621.13

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