Long-time behavior of nuclear spin decays in various lattices
Long-time behavior of nuclear spin decays in various lattices
复制标题
核自旋在各种晶格中的长期行为衰减
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
B. Saam
中科院分区：
文献类型：
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作者：
E. Sorte;B. Fine;B. Saam
多晶氙中{sup 129} π的横向NMR衰变最近被证明具有普适性质：在长时间范围内，这些衰变都收敛于相同的正弦调制指数函数，而与由一个或多个射频脉冲序列制备的初始横向自旋配置无关。目前的工作构成了一个更全面的调查这一现象。它检查几个不同的同位素浓度的{sup 129}氟的横向衰变，采用额外的脉冲序列，并在不同的材料进行类似的测量：{sup 19}氟单晶和多晶CaF{sub 2}。除了多晶CaF{sub 2}的长时间行为的观察受到实验分辨率的限制之外，所有这些系统都显示出长时间的普遍行为，其特征在于每个晶格的指数衰减系数和拍频的特定值是唯一的。这种行为已经在理论上预测的基础上的概念微观混沌。
The transverse NMR decays of {sup 129}Xe in polycrystalline xenon were recently shown to have a universal property: in the long-time regime these decays all converge to the same sinusoidally modulated exponential function irrespective of the initial transverse spin configuration prepared by a sequence of one or more radio frequency pulses. The present work constitutes a more comprehensive survey of this phenomenon. It examines transverse decays for several different isotopic concentrations of {sup 129}Xe, employs additional pulse sequences, and performs similar measurements in a different material: {sup 19}F in single-crystal and polycrystalline CaF{sub 2}. With the possible exception of polycrystalline CaF{sub 2} where the observation of the long-time behavior is limited by the experimental resolution, all these systems display the long-time universal behavior characterized by particular values of the exponential decay coefficient and beat frequency that were unique for each lattice. This behavior has been theoretically predicted based on the notion of microscopic chaos.