Development of a cryogenic duplexer for solid-state nuclear magnetic resonance.
To fully appreciate sensitivity enhancement achievable by reducing thermal noise at the detection coil for nuclear magnetic resonance (NMR), a duplexer operational at low temperature is required. In this work, we developed a cryogenic duplexer that can work below 50 K using GaAs diodes and rf-microelectrical mechanical systems switches. As the observed leakage of a rf pulse (100 W and 50 micros) through the duplexer is below 1 mW, it can be used not only for NMR in liquids but also for NMR in solids. We reported recently the cryocoil magic-angle spinning (MAS) probe [T. Mizuno et al., Rev. Sci. Instrum. 79, 044706 (2008)] into which was incorporated with this duplexer and a commercial rf preamplifier, we show that signal-to-noise ratio gain of 4.0 times can be achieved for (1)H MAS-NMR by lowering the detection-coil temperature to 12 K and the temperatures for the rf preamplifier and the duplexer to 43 K.
Mizuno
Takashi
T
JEOL Ltd., 1-2 Musashino 3-Chome, Akishima, Tokyo 196-8558, Japan. tmizuno@jeol.co.jp
Takegoshi
K
K