A High-Conversion-Factor, Double-Resonance Structure for High-Field Dynamic Nuclear Polarization
A High-Conversion-Factor, Double-Resonance Structure for High-Field Dynamic Nuclear Polarization
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DOI：
10.1007/s00723-009-0091-6
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发表时间：
2010-01-01
影响因子：
1
通讯作者：
Kentgens, A. P. M.
中科院分区：
文献类型：
--
作者：
Annino, G.;Villanueva-Garibay, J. A.;Kentgens, A. P. M.
这一贡献提出了一种新的设计的双共振结构的高场动态核极化工作在95 GHz和144 MHz，其中一个小型化的射频线圈集成在一个单模无辐射介质谐振器。在详细讨论了系统的设计原理后，通过微波和射频测量确定了系统的转换因子。所得到的结果，1.68 mT/W（1/2）的微波转换因子和0.8 mT/W（1/2）的射频转换因子，代表了双谐振结构中的最新技术。本文对氮氧自由基2，2，6，6-四甲基哌啶-1-氧基溶于水和二氧六环的混合溶液进行了电子顺磁共振（ESR）和液态（1H）核磁共振（NMR）的同时测量。在70 mW的微波功率下，在纳升大小的样品体积中，自由基浓度为10 mM时，获得了约-16的最大动态核极化增强。这些结果进行了讨论，鉴于建议的双谐振结构的进一步改进和应用。
This contribution presents a novel design of a double-resonance structure for high-field dynamic nuclear polarization operating at 95 GHz and 144 MHz, in which a miniaturized radiofrequency coil is integrated within a single-mode nonradiative dielectric resonator. After a detailed discussion of the design principles, the conversion factors of this system are determined by means of microwave and radiofrequency measurements. The obtained results, 1.68 mT/W(1/2) for the microwave conversion factor and 0.8 mT/W(1/2) for the radiofrequency conversion factor, represent the state-of-the-art among the double-resonance structures. Simultaneous electron paramagnetic resonance and liquid-state (1)H nuclear magnetic resonance experiments are performed on samples of nitroxide radical 2,2,6,6-tetramethylpiperidine-1-oxyl dissolved in a mixture of water and dioxane. A maximum dynamic nuclear polarization enhancement of about -16 is obtained at a microwave power of 70 mW with a radical concentration of 10 mM in nanoliter-sized sample volumes. These results are discussed in view of further improvements and applications of the proposed double-resonance structure.