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Rodriguez, Jorge H. 2011-05-07T12:43:11Z 2011-05-07T12:43:11Z Debrunner, Peter G. 10000-01-01 1995 The mixed valence centers of the diiron-oxo proteins uteroferrin and nitrosyl derivatives of hemerythrin have been studied by Mossbauer Spectroscopy. Simulations of data recorded in applied fields for the 4.2 K to 250 K temperature range have been performed with the intrinsic spin Hamiltonian $\rm {\cal H} = J{\bf S}\sb1\cdot{\bf S}\sb2 + \Sigma\sbsp{i=1}{2}\{{\bf S}\sb{i}\cdot\tilde D\sb{i}\cdot{\bf S}\sb{i} + \beta{\bf S}\sb{i}\cdot\tilde g\sb{i}\cdot{\bf H} + {\bf S}\sb{i}\cdot\tilde a\sb{i}\ \cdot\ {\bf I}\sb{i} + {\bf I}\sb{i}\cdot\tilde P\sb{i}\cdot {\bf I}\sb{i} - \beta\sb{n}g\sb{n}{\bf H}\cdot I\sb{i}\}.$ Values for the isotropic exchange constant J, zero field splitting parameters D$\sb{\rm i}$ and E$\sb{\rm i}$, electronic Zeeman tensors $\rm\tilde g\sb{i},$ magnetic hyperfine tensors $\rm\tilde a\sb{i},$ electric quadrupole splittings $\rm\Delta E\sb{Q}$ and isomer shifts, have been obtained for the two distinctly different iron sites of each protein. In both cases an intermediate coupling regime $\rm\Vert{J\over D\sb{i}}\Vert \ge 1$ was found and the zero field splitting strongly perturbs the eigenstates of the exchange interaction. From the spin Hamiltonian parameters, the electronic ground state and ligand field symmetry for the Fe$\sp{2+}$(S = 2) site of uteroferrin and for the $\rm\{FeNO\}\sp7(S = {3\over2})$ site of the nitric oxide derivative of hemerythrin were inferred. Knowledge of the electronic ground states allowed the interpretation of the magnetic hyperfine interactions with simple ligand field and molecular orbital models. Mossbauer spectra of two spin coupled iron-chromium complexes have also been analyzed in terms of effective spin Hamiltonians for their ground states. A highly effective genetic algorithm was used to search in the parameter space of the Hamiltonians. Made available in DSpace on 2011-05-07T12:43:11Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9624472.pdf: 5329152 bytes, checksum: 7713e433487e9ba59e435d8dd30fc17b (MD5) Previous issue date: 1995 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:44:49Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:19:47-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9624472 (UMI)AAI9624472 http://hdl.handle.net/2142/20576 eng Copyright 1995 Rodriguez, Jorge H. Chemistry, Physical Physics, Molecular Physics, Atomic Mossbauer studies of spin coupled binuclear iron centers in proteins text Chemistry Chemical Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.