Application of Continuously Frequency-Tunable 0.4 THz Gyrotron to Dynamic Nuclear Polarization for 600 MHz Solid-State NMR

作者：Matsuki Yoh; Ueda Keisuke; Idehara Toshitaka; Ikeda Ryosuke; Kosuga Kosuke; Ogawa Isamu; Nakamura Shinji; Toda Mitsuru; Anai Takahiro; Fujiwara Toshimichi^*

来源：Journal of Infrared Millimeter and Terahertz Waves, 2012, 33(7): 745-755.

DOI：10.1007/s10762-012-9890-1

• Gyrotron
• Dynamic nuclear polarization
• Solid-state NMR
• High-field spectroscopy

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).

• 出版日期2012-7