Multispin dynamics of the solid-state NMR free induction decay
Multispin dynamics of the solid-state NMR free induction decay
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DOI：
10.1103/physrevb.72.054427
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发表时间：
2005-08-01
影响因子：
3.7
通讯作者：
Ramanathan, C
中科院分区：
文献类型：
--
作者：
Cho, H;Ladd, TD;Ramanathan, C
本文对自旋为1/2的原子核在强塞曼场中的NMR自由感应衰减进行了新的实验研究。在π/2脉冲之后，在长期偶极哈密顿量下的演化保持塞曼本征基中的相干数，但改变状态中的相关自旋的数量。在偶极哈密顿量的作用下，观察到的信号随着单自旋、单量子相干态演化为多自旋相干态而衰减。为了探测FID过程中的多自旋动力学，我们测量了在通常的塞曼本征基以外的基中相干阶的增长。这一测量提供了第一个直接的实验观察的增长过程中的FID的相干多自旋相关。实验是用立方晶格的自旋（F-19在氟化钙）和线性自旋链（F-19在氟磷灰石）。可以看出，自旋的几何排列在高阶关联的发展中起着重要的作用。根据现有的理论模型的结果进行了讨论。
We present a new experimental investigation of the NMR free induction decay (FID) in a lattice of spin-1/2 nuclei in a strong Zeeman field. Following a pi/2 pulse, evolution under the secular dipolar Hamiltonian preserves the coherence number in the Zeeman eigenbasis, but changes the number of correlated spins in the state. The observed signal is seen to decay as single-spin, single-quantum coherences evolve into multiple-spin coherences under the action of the dipolar Hamiltonian. In order to probe the multiple-spin dynamics during the FID, we measured the growth of coherence orders in a basis other than the usual Zeeman eigenbasis. This measurement provides the first direct experimental observation of the growth of coherent multiple-spin correlations during the FID. Experiments were performed with a cubic lattice of spins (F-19 in calcium fluoride) and a linear spin chain (F-19 in fluorapatite). It is seen that the geometrical arrangement of the spins plays a significant role in the development of higher-order correlations. The results are discussed in light of existing theoretical models.