Quantum rotor induced hyperpolarization
Quantum rotor induced hyperpolarization
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量子转子诱发超极化
DOI：
10.1073/pnas.0908421107
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
U. Günther
中科院分区：
文献类型：
--
作者：
C. Ludwig;M. Saunders;I. Marín;U. Günther
尽管其广泛的适用性NMR一直受到其固有的低灵敏度的限制。超极化方法有可能克服这一限制，并在非原位动态核极化（DNP）的情况下，大的增强因子已经实现。尽管过去已经描述了许多其他偏振方法，包括化学和仲氢诱导的偏振和光泵浦，但DNP最近是最流行的。在这里，我们提出了一个额外的极化机制所产生的量子转子效应的甲基，它产生的温度< 1.5 K的极化和干扰DNP在这样的温度。由该机制产生的极化通过碳结合质子有效地转移。虽然量子转子极化已经在小范围的分子中进行了非常详细的研究，但我们在温度< 1.5 K时观察到了更广泛的具有非常不同极化率的物质的这种效应。此外，我们报告跨质子链的量子转子极化转移。所观察到的效应不仅影响低温DNP实验中的极化，而且还开辟了一条新的独立途径来产生增强的NMR灵敏度。
Despite its broad applicability NMR has always been limited by its inherently low sensitivity. Hyperpolarization methods have the potential to overcome this limitation and, in the case of ex situ dynamic nuclear polarization (DNP), large enhancement factors have been achieved. Although many other polarization methods have been described in the past, including chemically and parahydrogen-induced polarization and optical pumping, DNP has recently been the most popular. Here we present an additional polarization mechanism arising from quantum rotor effects in methyl groups, which generates polarizations at temperatures < 1.5 K and interferes with DNP at such temperatures. The polarization generated by this mechanism is efficiently transferred via carbon bound protons. Although quantum rotor polarizations have been studied for a small range of molecules in great detail, we observe such effects for a much broader range of substances with very different polarization rates at temperatures < 1.5 K. Moreover, we report transfer of quantum rotor polarization across a chain of protons. The observed effect not only influences the polarization in low-temperature DNP experiments but also opens a new independent avenue to generate enhanced sensitivity for NMR.
影响因子：
15
作者：
Joo, Chan-Gyu;Hu, Kan-Nian;Griffin, Robert G.
通讯作者：
Griffin, Robert G.