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Numerical studies of the nuclear hyperfine interactions in manganese dichloride tetrahydrate

University of British Columbia

The nuclear magnetic resonance of oriented nuclei (NMRON) is a useful technique for the study of magnetic solids, and is especially important for investigating very dilute systems. The work in this thesis complements experimental NMRON studies of ⁵⁴Mn-MnCl₂.4H₂O by the nuclear orientation group at the University of British Columbia. The manganese nucleus experiences a hyperfine interaction which is due primarily to a magnetic (Zeeman) interaction, but which also has a small contribution due to the interaction between the electric quadrupole moment eQ of the nucleus and the electric field gradient eq arising from the surrounding ionic charges in the lattice. The latter interaction can be treated as a perturbation on the Zeeman interaction and results in shifts in the nuclear spin energy levels, so that there are 21 resonant frequencies for spin 1. The electric field gradient is calculated by treating these ions as point charges, and a computer program to do this calculation is developed. The result of this lattice sum, eq , has to be multiplied by the Sternheimer anti-shielding factor which takes into account the amplifying effect due to the distortion by the field gradient of the electrons on the atom of interest: this factor is known for the manganese ion. As a check, the case of ⁵⁵Mn in MnF₂ is investigated because the value of |e²qQ| has been derived from experiment and an independent calculation. The results for e²qQ/h are: experiment - 11.7±0.03 MHz; previous calculation - 8.8 MHz; our calculation - 8.5±0.4 MHz. [the rest of the abstract can be found in the attached PDF file]

Text

2010-04-21

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http://hdl.handle.net/2429/23978

Physics

University of British Columbia

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