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NMR Evidence for Contact Hyperfine Coupling in Paramagnetic UF 4
Author(s) -
Pintar M.
Publication year - 1966
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19660140204
Subject(s) - hyperfine structure , paramagnetism , electron paramagnetic resonance , fluorine , ion , covalent bond , fermi contact interaction , electron , chemistry , absorption (acoustics) , magnetic field , coupling (piping) , atomic physics , materials science , nuclear magnetic resonance , condensed matter physics , physics , organic chemistry , quantum mechanics , metallurgy , composite material
The F 19 NMR absorption in powdered UF 4 is investigated in the temperature range 122 to 433 °K at magnetic fields between 10000 and 5000 G. The fluorine absorption pattern in this paramagnetic material with seven nonequivalent F‐sites in the unit cell is reproduced qualitatively by a sum of six asymmetric component lines (H ∥ ‐– H ⊥ ) −1/2 × (H–H ⊥ ) −1/2 , some of which are shifted in the high field direction, and some in the low field direction. The occurrence of low‐field shifted components provides evidence of contact hyperfine interaction between the magnetic electrons and the fluorine nuclei whereas the occurrence of high‐field shifted components may arise from indirect coupling through electron transfer, and indicates partial covalent bonding between the magnetic electrons and the surrounding fluorine ions. This is supported by magnetic susceptibility and EPR data.