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Sample Ripening through Nanophase Separation Influences the Performance of Dynamic Nuclear Polarization
Author(s) -
Weber Emmanuelle M. M.,
Sicoli Giuseppe,
Vezin Hervé,
Frébourg Ghislaine,
Abergel Daniel,
Bodenhausen Geoffrey,
Kurzbach Dennis
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201800493
Subject(s) - polarization (electrochemistry) , nanoscopic scale , chemical physics , homogeneous , counterintuitive , spectroscopy , materials science , glycerol , chemical engineering , radical , chemistry , analytical chemistry (journal) , nanotechnology , thermodynamics , chromatography , organic chemistry , physics , quantum mechanics , engineering
Mixtures of water and glycerol provide popular matrices for low‐temperature spectroscopy of vitrified samples. However, they involve counterintuitive physicochemical properties, such as spontaneous nanoscopic phase separations (NPS) in solutions that appear macroscopically homogeneous. We demonstrate that such phenomena can substantially influence the efficiency of dynamic nuclear polarization (DNP) by factors up to 20 % by causing fluctuations in local concentrations of polarization agents (radicals). Thus, a spontaneous NPS of water/glycerol mixtures that takes place on time scales on the order of 30–60 min results in a confinement of polarization agents in nanoscopic water‐rich vesicles, which in return affects the DNP. Such effects were found for three common polarization agents, TEMPOL, AMUPol and Trityl.