講座

磁気共鳴分光
III．緩和

Magnetic Resonance Spectroscopy
III．Nuclear Spin Relaxation

高橋 栄夫
Hideo TAKAHASHI

核スピン緩和現象はNMR測定の様々な局面に関与している．縦緩和，横緩和などはNMR測定そのものに深く関わる緩和現象であり，分子の立体構造決定に必須なNOE現象は交差緩和によるものである．さらに近年，交差相関緩和を利用した測定法が多く開発されてきている．本稿では，これら緩和現象を統一的に理解するため，半古典的緩和解析法に由来する演算子計算を用いた解説を行う．

Nuclear spin relaxation is one of the fundamental aspects of Nuclear Magnetic Resonance (NMR). Transverse relaxation rate governs the linewidth of the resonance, and longitudinal relaxation rate affects the determination of the recycle delay for each acquisition. On the other hand, cross-relaxation causes the nuclear Overhauser effect (NOE) which gives us distance information used for the 3D structure determination of molecules. Recently, cross-correlated relaxation has been effectively utilized to develop novel NMR measurements. In this review, semi-classical treatment of relaxation theory is briefly introduced, and by utilizing the derived double commutator operation, various aspects of nuclear spin relaxation are investigated in terms of molecular motions.

Keywords:Dipole-dipole interaction, Chemical shift anisotropy, Molecular motion, Cross-correlated relaxation