Premium
Electron Decoupling with Chirped Microwave Pulses for Rapid Signal Acquisition and Electron Saturation Recovery
Author(s) -
Alaniva Nicholas,
Saliba Edward P.,
Sesti Erika L.,
Judge Patrick T.,
Barnes Alexander B.
Publication year - 2019
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201900139
Subject(s) - spins , electron , decoupling (probability) , hyperpolarization (physics) , microwave , magic angle spinning , nuclear magnetic resonance , polarization (electrochemistry) , atomic physics , chemistry , molecular physics , materials science , analytical chemistry (journal) , physics , nuclear magnetic resonance spectroscopy , condensed matter physics , quantum mechanics , control engineering , engineering , chromatography
Dynamic nuclear polarization (DNP) increases NMR sensitivity by transferring polarization from electron to nuclear spins. Herein, we demonstrate that electron decoupling with chirped microwave pulses enables improved observation of DNP‐enhanced 13 C spins in direct dipolar contact with electron spins, thereby leading to an optimal delay between transients largely governed by relatively fast electron relaxation. We report the first measurement of electron longitudinal relaxation time (T 1e ) during magic angle spinning (MAS) NMR by observation of DNP‐enhanced NMR signals (T 1e =40±6 ms, 40 m M trityl, 4.0 kHz MAS, 4.3 K). With a 5 ms DNP period, electron decoupling results in a 195 % increase in signal intensity. MAS at 4.3 K, DNP, electron decoupling, and short recycle delays improve the sensitivity of 13 C in the vicinity of the polarizing agent. This is the first demonstration of recovery times between MAS‐NMR transients being governed by short electron T 1 and fast DNP transfer.