Crystal-field perturbation

Investigate the effect of spin-orbit coupling on the crystal-field levels of a Ce3+ ion substituting for Ca2 + in CaF2 with a nearest-neighbor O2 ion (see Problem 7.2). Is any further splitting of these levels to be expected if the site symmetry at Ce3+ is lowered to Cs by a further crystal-field perturbation that is weaker than //s.i. ... 

When a Jahn-Teller-distorted C q molecule is placed in a solid-state environment, strain or crystal-field perturbations may play a decisive role in the selection and/or enhancement of the Jahn-Teller-distorted configuration. In an attempt to investigate the Jahn-Teller-distorted C6 0 molecules in the solid state, C60-tetraphenylphosphonium iodide has been synthesized and studied [40]. The well-known Flu(l) and Flu(2) modes were found to split into doublets at room temperature indicating a D5d or D3d and not a D2u Jahn-Teller configuration. These results are consistent with a dynamic Jahn-Teller effect in the strong coupling limit or with a static distortion stabilized by the low-symmetry perturbations. 

The Polarized Spectrum of Anthracene. Part II. Weak Transitions and Second-Order Crystal Field Perturbations. 

The complex between Fe + and EDTA has been studied (1) as a single crystal in Rb[CoEDTA]. Single-crystal X-ray structure analysis shows that the Fe +EDTA complex is 7-coordinate with an H2O molecule coordinating to the Fe, whereas the CoEDTA complex anion is 6-coordinate. Aasa et al. (1) consider that the Fe + remains 7-coordinate in the Rb[CoEDTA] host lattice from their ESR data. The g 4 values and the second-order parameters D and E, which are sensitive to crystal field perturbations, are very close to those in the protein transferrin (3). The complex ferric phthalocyanine chloride in the solid state has been variously reported as having a g value of 3.8 (362) and 2.5 (387). It is thought to have a spin S = f since its magnetic moment is 3.32 B.M. 

The transitions within 5f shells are sharp, lanthanide-like lines for heavier actinides. They are considerably broadened and ligand-field dependent for earlier actinides where 5f orbitals contribute much more to the metal-ligand bonding. These transitions are Laporte-forbidden and their intensity (10 times greater than 4f transitions) is due to crystal field perturbations and vibronic coupling. 

Note that the dimension of the crystal-field coefficient Akq is energy whereas the dimension of the crystal-field parameter 5 is ML T", or energy (Gorller-Walrand and Binnemans 1996). The 5 include the radial integral r. The Hamiltonian for the crystal-field perturbation is written here as a potential, because this is commonly done in the literature. 

Further discussion of the crystal field perturbation and crystal field parameters will be continued in Section 1.3.7. 

To remove these discrepancies, the Hamiltonian is extended to account for the effects of the electron correlation on the anisotropic crystal-field interactions in the 4f shell. Two-body operators are necessary to describe the correlation effects. The expression correlation crystal field is used for the two-electron part of the crystal-field perturbation. A review of the theoretical development of correlation crystal-field theory is given by Garcia and Faucher (1995). A practical problem for taking the correlation effects into account is the enormous number of parameters required. 

The fine-splitting in the absorption, excitation and luminescence spectra of rare-earth /3-diketonate complexes is due to the crystal-field perturbation. The splitting patterns is determined by the symmetry of the coordination polyhedron around the rare-earth ion and by... 

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