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A Low‐Temperature Broadband NMR Probe for Multinuclear Cross‐Polarization
Author(s) -
Aghelnejad Behdad,
Bodenhausen Geoffrey,
Marhabaie Sina
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201900723
Subject(s) - liquid helium , polarization (electrochemistry) , superfluid helium 4 , microwave , amplifier , helium , amplitude , atmospheric temperature range , atomic physics , radio frequency , chemistry , analytical chemistry (journal) , materials science , optoelectronics , physics , optics , electrical engineering , quantum mechanics , cmos , chromatography , meteorology , engineering
Dissolution dynamic nuclear polarization (D‐DNP) probes are usually designed for one or at most two specific nuclei. Investigation of multiple nuclei usually requires manufacturing a number of costly probes. In addition, changing the probe is a time‐consuming process since a system that works at low temperature (usually between 1.2 and 4.2 K) must be warmed up, thus increasing the risks of contamination. Here, an efficient apparatus is described for D‐DNP designed not only for microwave‐enhanced direct observation of a wide range of nuclei S such as 1 H, 13 C, 2 H, 23 Na, and 17 O, but also for cross‐polarization (CP) from I = 1 H to such S nuclei. Unlike most conventional designs, the tuning and matching circuits are partly immersed in superfluid helium at temperatures down to 1.2 K. Intense radio‐frequency (RF) fields with amplitudes on the order of 50 kHz or better can be applied simultaneously to both nuclei I and S using RF amplifiers with powers on the order of 90 and 80 W, respectively, without significant losses of liquid helium. The system can operate at temperatures over a wide range between 1.2 and 300 K.