Application of Continuously Frequency-Tunable 0.4 THz Gyrotron to Dynamic Nuclear Polarization for 600 MHz Solid-State NMR
Application of Continuously Frequency-Tunable 0.4 THz Gyrotron to Dynamic Nuclear Polarization for 600 MHz Solid-State NMR
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DOI：
10.1007/s10762-012-9890-1
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发表时间：
2012-07-01
影响因子：
2.9
通讯作者：
Fujiwara, Toshimichi
中科院分区：
文献类型：
--
作者：
Matsuki, Yoh;Ueda, Keisuke;Fujiwara, Toshimichi
在本文中，我们提出的结果表明，在动态核极化（DNP）增强的固态NMR（SSNMR）光谱中的一个最高的磁场，B（0）= 14.1 T（600 MHz的H-1拉莫尔频率）的连续频率可调谐的0.4太赫兹回旋管的效用。我们的回旋管称为FU CW VI产生亚毫米波在0.4太赫兹附近的频率与输出功率为4-25 W和可调谐范围超过1 GHz的回旋管腔的磁场扫描。我们观察到中心频率的整体下移，在高辐射占空因数和束电流下，可能是由于加热引起的腔热膨胀，但可调谐范围没有显著变化。频率可调谐性促进了DNP共振条件的优化，而无需对高分辨率NMR磁体进行耗时的场扫描，并使我们能够观察到SSNMR信号的大幅增强（在90 K下，Δ（DNP）= 12）。
In this paper we present results that demonstrate the utility of a continuously frequency-tunable 0.4 THz-gyrotron in a dynamic nuclear polarization (DNP)-enhanced solid-state NMR (SSNMR) spectroscopy at one of the highest magnetic fields, B (0) = 14.1 T (600 MHz for H-1 Larmor frequency). Our gyrotron called FU CW VI generates sub-mm wave at a frequency near 0.4 THz with an output power of 4-25 W and a tunability over a range of more than 1 GHz by sweeping the magnetic field at the gyrotron cavity. We observed overall down shifting of the central frequency by up to similar to 1 GHz at high radiation duty factors and beam current, presumably due to the cavity thermal expansion by a heating, but the tunable range was not significantly changed. The frequency tunability facilitated the optimization of the DNP resonance condition without time-consuming field-sweep of the high-resolution NMR magnet, and enabled us to observe substantial enhancement of the SSNMR signal (epsilon (DNP) = 12 at 90 K).