LONGITUDINAL NUCLEAR SPIN-SPIN RELAXATION,
LONGITUDINAL NUCLEAR SPIN-SPIN RELAXATION,
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纵向核自旋-自旋弛豫，
DOI：
10.1103/physrev.133.a1616
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发表时间：
1964
期刊：
影响因子：
--
通讯作者：
E. Hahn
中科院分区：
文献类型：
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作者：
R. L. Strombotne;E. Hahn
本文从实验和理论上研究了在绝热退磁过程制备的有序自旋系统中，非绝热地施加突然的单向阶跃磁场后出现的核磁化现象。磁化强度表现出关于非零平衡值的阻尼振荡。振荡频率对应于拉莫尔频率的基波和谐波分量，由局域偶极子和外部阶跃场的联合作用决定。当内部有序的偶极-偶极相互作用能量与突然施加的塞曼能量库交换时，振荡出现。一个密度矩阵计算进行二阶随时间变化的微扰理论，结合高斯衰减模型，占所观察到的时间内的衰减时间的振荡。在单CaF/sub 2/晶体中的氟核进行了研究，为各种晶体取向相对于所施加的阶跃场。在阶跃场应用之后的很长时间内，偶极-偶极和塞曼储层之间的热平衡的实现允许使用自旋温度概念来预测沿着阶跃场发展的磁化。（auth）
The nuclear magnetization that appears after a sudden unidirectional step magnetic field is applied non-adiabatically to an ordered spin system which has been prepared by the process of adiabatic demagnetization was studied experimentally and theoretically. The magnetization exhibits damped oscillations about a non-vanishing equilibrium value. The oscillation frequencies correspond to the fundamental and harmonic components of Larmor frequency determined by the combined effect of local dipole and external step fields. The oscillations arise as the internally ordered dipole-dipole interaction energy exchanges with the suddenly imposed Zeeman energy reservoir. A density matrix calculation carried to second order in time dependent perturbation theory, combined with a gaussian decay model, accounts for the observed oscillations within times comparable to the decay time. Fluorine nuclei in single CaF/sub 2/ crystals were studied for various crystal orientations with respect to the applied step field. For long times after step field application, the attainment of thermal equilibrium between dipole-dipole and Zeeman reservoirs permits prediction, using the spin temperature concept, of magnetization developed along the step field. (auth)