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NMR shielding in helium‐3 atoms modified by gaseous nitrogen and oxygen
Author(s) -
Garbacz Piotr,
Misiak Maria,
Jackowski Karol
Publication year - 2020
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.5030
Subject(s) - chemistry , electromagnetic shielding , helium , paramagnetism , fermi contact interaction , unpaired electron , molecule , dipole , nitrogen , atomic physics , molecular physics , analytical chemistry (journal) , condensed matter physics , organic chemistry , physics , engineering , electrical engineering
Helium‐3 nuclear magnetic resonance ( 3 He NMR) measurements were carried out for the gaseous mixtures of helium‐3 with pure nitrogen and synthetic air as the solvents. It was found that 3 He shielding is linearly dependent on solvent density up to approx. 6 mol/L. At higher density of the gaseous solvent, the change of 3 He shielding is nonlinear and especially distinct when helium‐3 atoms can interact with two O 2 molecules. The interaction with paramagnetic oxygen molecules can induce two kinds of 3 He shielding changes: (1) due to the isotropic Fermi contact interaction and (2) from the dipolar magnetic interaction between unpaired O 2 electrons and 3 He nuclear magnetic dipole moment. The two paramagnetic effects in helium‐3 shielding cannot be experimentally separated, although for such small molecular objects, they could be presumably modeled by advanced theoretical calculations.