Long-lived polarization protected by symmetry
Long-lived polarization protected by symmetry
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DOI：
10.1063/1.4896895
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发表时间：
2014-10-07
影响因子：
4.4
通讯作者：
Warren, Warren S.
中科院分区：
文献类型：
--
作者：
Feng, Yesu;Theis, Thomas;Warren, Warren S.
在本文中，我们阐明，理论和实验，分子图案，允许长寿命的偏振保护的对称性（LOLIPOPS）。基本的组装原理从一对化学等价的核开始，支持长寿命的单重态，并通过耦合到额外的自旋对来完成。LOLIPOPS可以创建成各种大小;在这里，我们回顾四自旋系统，介绍六自旋系统的群论分析，并通过模拟探索八自旋系统。重点是AA'XnXn'自旋系统，其中通常A自旋是N-15或C-13，X自旋是质子。我们描述了访问状态的对称性，我们详细说明了用于访问这些状态的脉冲序列，我们量化了可以存储为LOLIPOPS的极化分数，我们阐明了如何从A或X极化访问受保护的状态，我们研究了这些自旋系统的行为后，引入一个小的化学位移差。(C)2014 AIP出版有限责任公司。
In this paper we elucidate, theoretically and experimentally, molecular motifs which permit Long-Lived Polarization Protected by Symmetry (LOLIPOPS). The basic assembly principle starts from a pair of chemically equivalent nuclei supporting a long-lived singlet state and is completed by coupling to additional pairs of spins. LOLIPOPS can be created in various sizes; here we review four-spin systems, introduce a group theory analysis of six-spin systems, and explore eight-spin systems by simulation. The focus is on AA'XnXn' spin systems, where typically the A spins are N-15 or C-13 and X spins are protons. We describe the symmetry of the accessed states, we detail the pulse sequences used to access these states, we quantify the fraction of polarization that can be stored as LOLIPOPS, we elucidate how to access the protected states from A or from X polarization and we examine the behavior of these spin systems upon introduction of a small chemical shift difference. (C) 2014 AIP Publishing LLC.