Shuttle DNP spectrometer with a two-center magnet
Shuttle DNP spectrometer with a two-center magnet
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DOI：
10.1039/c003381b
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发表时间：
2010-01-01
影响因子：
3.3
通讯作者：
Griesinger, Christian
中科院分区：
文献类型：
--
作者：
Krahn, Alexander;Lottmann, Philip;Griesinger, Christian
描述了一种DNP装置，其中液体样品在0.34T的磁场中被电子-核Overhauser效应超极化，并转移到14.09T的磁场中进行核磁共振检测。与以前的设置不同，使用两个专用磁铁进行极化和检测，在14.09T屏蔽低温磁铁的内孔中插入了专用铁磁垫系统，以在磁中心上方的杂散场中提供均匀的低场区域。样品在低场极化后，通过气动穿梭系统在40ms内转移到高场磁心。在我们的装置中，使用标准的高分辨率逆(1)H/(13)C选择探针进行核磁共振检测，并使用自制的工作在TM(110)模式下的EPR腔进行偏振。首先给出了实验数据。对于5 mm 4-oxo-Tempo-D，(15)N(Tempone)/H(2)O样品，我们在高场位置观察到最大质子Overhauser增强，最高可达epsilon(Hf)=-3.7。虽然这再现了在旧设置中也观察到的DNP增强，但在新设置中，我们观察到在旧设置中不可能增强的较大分子的增强。因此，我们可以首次证明Overhauser增强了葡萄糖和2，2-二甲基-2-硅戊烷-5-磺酸钠(DSS)在D(2O)中的高分辨质子光谱，其中高分辨光谱是在低场极化样品后在高场位置获得的。
A DNP set-up is described where a liquid sample is hyperpolarized by the electron-nucleus Overhauser effect in a field of 0.34 T and transferred to a field of 14.09 T for NMR detection. In contrast to a previous set-up, using two dedicated magnets for polarization and detection, a dedicated ferroshim system was inserted into the bore of a 14.09 T shielded cryomagnet to provide a homogeneous low-field region in the stray field above the magnetic center. After polarization in the low-field the sample is transferred to the high-field magnetic center within 40 ms by a pneumatic shuttle system. In our set-up a standard high-resolution inverse (1)H/(13)C selective probe was used for NMR detection and a homebuilt EPR cavity, operating in the TM(110) mode was used for polarisation. First experimental data are presented. We observed a maximum proton Overhauser enhancement of up to epsilon(HF) = -3.7 in the high-field position for a 5 mM 4-Oxo-TEMPO-D, (15)N (TEMPONE)/H(2)O sample. While this reproduces the DNP enhancement observed also in the old set-up, with the new set-up we observe enhancement on larger molecules that were impossible to enhance in the old set-up. Therefore, we can demonstrate for the first time Overhauser enhanced high resolution proton spectra of glucose and 2,2-dimethyl-2-silapentane-5-sulfonic acid sodium salt (DSS) in D(2)O, where the high resolution spectrum was acquired in the high-field position after polarizing the sample in the low-field.