Robertson, Richard Earl (1960) I. Isotropic nuclear resonance shifts. II. The magnetic resonance properties of some sandwich molecules. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-07062006-083552
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Isotropic Nuclear Resonance Shifts:
It is shown that isotropic or average nuclear resonance shifts for a nucleus in a paramagnetic molecule in solution, and in a polycrystalline solid, can be used to distinguish between Fermi contact and "pseudo contact" contributions to isotropic nuclear hyperfine interactions. The pseudo contact interaction is that isotropic hyperfine coupling which arises from the combined effects of (electron-spin)-(nuclear-spin) coupling, (electron-orbit)-(nuclear-spin) coupling, and electron spin-orbit interaction. When the magnetic hyperfine interaction between the electronic moment and nuclear spin is approximated by a point dipolar interaction, and the isotropic hyperfine interaction is exclusively pseudo contact, then the isotropic nuclear shift in a polycrystalline solid exceeds the solution shift by the factor [...]/[...] where [...] and [...] are the spectroscopic splitting factors parallel and perpendicular to the molecular symmetry axis. Isotropic shifts due to the Fermi contact interaction are the same for both solid state and solution cases.
The Magnetic Resonance Properties of Some Sandwich Molecules:
Using the results of the two models as a first orientation the results of the magnetic susceptibility experiments (i.e., the observed deviation from spin only values) are used to choose appropriate arrangements for the three low-lying one-electrons in calculating the fine structure. The fine structure is considered for both when the Jahn-Teller effect splits a degenerate orbital ground state and when spin-orbit interaction splits the orbital ground state without the Jann-Teller distortion. However, it is found that the Jahn-teller effect operates when appropriate in all the molecules and ions with the possible exception of [...]. Expressions are given for the g-factors and zero-field splittings, although the lack of knowledge as to the values of many of the parameters precluded numerical estimates in most cases.
Hyperfine structure is considered although not in much detail. Cognizance is taken of the fact the "exchange polarization", which results from paramagnetism of the ion causing the [alpha] and [beta] spins in the [...], [...], and [...] configurations to be in slightly different orbitals, leads to negative hyperfine coupling coefficients while unpaired electrons being in orbitals having s-character leads to a positive coupling coefficient.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Chemistry and Chemical Engineering|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||1 January 1960|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||26 Jul 2006|
|Last Modified:||26 Dec 2012 02:54|
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