Accessing Long-Lived Disconnected Spin-1/2 Eigenstates through Spins > 1/2
Accessing Long-Lived Disconnected Spin-1/2 Eigenstates through Spins > 1/2
复制标题
DOI：
10.1021/ja505792j
复制
发表时间：
2014-10-29
影响因子：
15
通讯作者：
Warren, Warren S.
中科院分区：
文献类型：
--
作者：
Claytor, Kevin;Theis, Thomas;Warren, Warren S.
化学上等效（或接近等效）的自旋 1/2 核对已被证明可以产生断开的本征态，与纯磁化 (T-1) 的寿命相比，其寿命非常长。这里，已知具有可接近的长寿命状态的分子类别被扩展为包括具有化学等效自旋 1/2 核的分子，通过与自旋 > 1/2 的核（在本例中为氘）耦合来访问。起初，这似乎令人惊讶，因为已知自旋 > 1/2 的原子核中存在的四极相互作用会导致快速弛豫。然而，研究表明，氘和碳之间的标量耦合可以引导群体进入和退出长寿命状态，即不受主要弛豫机制影响的状态。这意味着考虑将 C-13 对直接与氘（甚至 N-14）结合的化合物作为极化存储的候选者可能是可行的。此外，实验表明，在自然丰度下对具有 C-13 对的分子进行简单氘化足以成功测量寿命。
Pairs of chemically equivalent (or nearly equivalent) spin-1/2 nuclei have been shown to create disconnected eigenstates that are very long-lived compared with the lifetime of pure magnetization (T-1). Here the classes of molecules known to have accessible long-lived states are extended to include those with chemically equivalent spin-1/2 nuclei accessed by coupling to nuclei with spin > 1/2, in this case deuterium. At first, this appears surprising because the quadrupolar interactions present in nuclei with spin > 1/2 are known to cause fast relaxation. Yet it is shown that scalar couplings between deuterium and carbon can guide population into and out of long-lived states, i.e., those immune from the dominant relaxation mechanisms. This implies that it may be practical to consider compounds with C-13 pairs directly bound to deuterium (or even N-14) as candidates for storage of polarization. In addition, experiments show that simple deuteration of molecules with C-13 pairs at their natural abundance is sufficient for successful lifetime measurements.