NMR Spin-Lock Induced Crossing (SLIC) dispersion and long-lived spin states of gaseous propane at low magnetic field (0.05 T)
NMR Spin-Lock Induced Crossing (SLIC) dispersion and long-lived spin states of gaseous propane at low magnetic field (0.05 T)
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DOI：
10.1016/j.jmr.2017.01.014
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发表时间：
2017-03-01
影响因子：
2.2
通讯作者：
Chekmenev, Eduard Y.
中科院分区：
文献类型：
--
作者：
Barskiy, Danila A.;Salnikov, Oleg G.;Chekmenev, Eduard Y.
当仲氢在低磁场（例如 0.05 T）中与丙烯反应时，反应产物丙烷会形成大量的赝单线核自旋态。我们研究了如何使用自旋锁诱导交叉 (SLIC) 技术将超极化气态丙烷的这些赝单重自旋态转换为可观测的磁化强度，并直接在 0.05 T 处检测 H-1 NMR 信号。NMR 信号对 B-1 功率（SLIC 幅度）依赖性的理论模拟和实验研究表现出良好解析的色散，这是由自旋-自旋引起的 丙烷八质子自旋系统中的耦合。我们还通过改变超极化丙烷产生和 SLIC 检测之间的时间来测量这些伪单线长寿命自旋态 (LISS) 的指数衰减时间常数（T-uss 或 T-s）。我们发现，在所研究的压力范围内（高达 7.6 atm）的相同条件下，Ts 平均比相应的 T-1 值长大约 3 倍。此外，在气相压力高于 7 个大气压时，T-s 可能超过 13 秒。这些结果与之前的报告一致，它们证实了长寿命超极化丙烷作为肺部成像的可吸入气体造影剂以及作为使用低场核磁共振和磁共振成像研究多孔介质的分子示踪剂的巨大潜力。 (C) 2017 Elsevier Inc. 保留所有权利。
When parahydrogen reacts with propylene in low magnetic fields (e.g., 0.05 T), the reaction product propane develops an overpopulation of pseudo-singlet nuclear spin states. We studied how the Spin-Lock Induced Crossing (SLIC) technique can be used to convert these pseudo-singlet spin states of hyperpolarized gaseous propane into observable magnetization and to detect H-1 NMR signal directly at 0.05 T. The theoretical simulation and experimental study of the NMR signal dependence on B-1 power (SLIC amplitude) exhibits a well-resolved dispersion, which is induced by the spin-spin couplings in the eight-proton spin system of propane. We also measured the exponential decay time constants (T-uss or T-s) of these pseudo-singlet long-lived spin states (LISS) by varying the time between hyperpolarized propane production and SLIC detection. We have found that, on average, Ts is approximately 3 times longer than the corresponding T-1 value under the same conditions in the range of pressures studied (up to 7.6 atm). Moreover, T-s may exceed 13 s at pressures above 7 atm in the gas phase. These results are in agreement with the previous reports, and they corroborate a great potential of long-lived hyperpolarized propane as an inhalable gaseous contrast agent for lung imaging and as a molecular tracer to study porous media using low-field NMR and MRI. (C) 2017 Elsevier Inc. All rights reserved.