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'Electron Paramagnetic Resonance EPR' in keywords
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2001 (3)
2000 (1)
1Author    Shao-Yi Wu, Wen-Chen ZhengRequires cookie*
 Title    Defect Structure of Co 2+ Center in 05-LiIO 3 Crystal  
 Abstract    In this paper we establish the formulas of EPR g factors g», for 3d 7 ions in trigonal octahedral crys-tals from a cluster approach. In these formulas, the contributions from configuration interaction-and covalency-effects are considered. The parameters related to both effects can be determined from the optical spectra and the structural parameters of the studied crystal. With these formulas, the defect struc-ture of a Co 2+ center in a-LiI0 3 crystal is studied. It is found that, to reach good fits between the cal-culated and observed g», g ± , the O ions between Co 2+ and Li + vacancy (V Li) should shift away from the V u by about 0.49 A. "Hie displacement direction is consistent with those obtained for Cr 3+ , Fe 3+ , and Mn 2 centers in a-LiI0 3 crystals as well as with the expectation based on the electrostatic interac-tion model. 
  Reference    Z. Naturforsch. 55a, 828—832 (2000); received June 29 2000 
  Published    2000 
  Keywords    Electron Paramagnetic Resonance (EPR), Crystal-field Theory, Defect Structure, Co 2+, a-LiI0 3 Crystal 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0828.pdf 
 Identifier    ZNA-2000-55a-0828 
 Volume    55 
2Author    Shao-Yi Wu, Wen-Chen ZhengRequires cookie*
 Title    Theoretical Studies of the g Factors for Co2+ in MgO and CaO Crystals  
 Abstract    This paper presents a cluster approach to the calculation of the g factors for 3d7 ions in cubic oc­ tahedral crystals, in which the parameters related to the configuration interaction and the covalency reduction effects are obtained from optical spectra of the studied crystals, and so no adjustable parameters are applied. From the approach, the g factors for MgO:Co2+ and CaO:Co2+ are cal­ culated. The calculated results show good agreement with the observed values. The experimental values of g < 4.333 (the first order value in absence of configuration and covalency interactions) for MgO:Co2+ and g > 4.333 for CaO:Co2+ are also explained. 
  Reference    Z. Naturforsch. 56a, 249—252 (2001); received October 13 2000 
  Published    2001 
  Keywords    Electron Paramagnetic Resonance (EPR), Crystal-field Theory, Co2+ Ion, MgO, CaO 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0249.pdf 
 Identifier    ZNA-2001-56a-0249 
 Volume    56 
3Author    Shao-Yi Wu, Wen-Chen ZhengRequires cookie*
 Title    Spin-lattice Coupling Coefficient G ^ of KMgF3:Mn2+ Calculated from Two Cases  
 Abstract    The high (fourth) order perturbation formulas based on the dominant spin-orbit coupling mech­ anism for the zero-field splittings D m of a 6S-state ion in trigonal symmetry and E [ha in rhombic symmetry are derived from the strong field scheme. Two analytic expressions of the spin-lattice coupling coefficient G 4 4 obtained from the formulas of and E rho are established by using a simple and uniform method. Based on the two expressions, the coefficients G 4 4 for KMgF3:Mn2+ are calculated in two cases. The results show that the lowest (third) order perturbation formulas of and E ^ 0 are too simple and too approximate to give reasonable and consistent values of G 44, whereas when the fourth-order perturbation terms D (^ and E ^ 0 are considered, the calculated values of G 44 (= G 44 + G '^) in both cases are not only close to each other, but also in agreement with the observed value. So, the fourth-order perturbation terms cannot be neglected. 
  Reference    Z. Naturforsch. 56a, 253—256 (2001); received November 28 2000 
  Published    2001 
  Keywords    Spin-lattice Coupling Coefficient, Electron Paramagnetic Resonance (EPR), Crystal-field Theory, Mn2+, KMgF3 PACS: 7630Fc, 7170Ch 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0253.pdf 
 Identifier    ZNA-2001-56a-0253 
 Volume    56 
4Author    Shao-Yi Wu, Wen-Chen ZhengRequires cookie*
 Title    Investigations of the EPR Parameters and Local Structures for Two Tetragonal Cr3* Centers in NH4C1 Crystal  
 Abstract    In this paper, the zero-field splittings D and g factors g», g± at room temperature for two tetragonal Cr3+ centers in NH4Cl:Cr3+ crystal have been investigated by a two-spin-orbit (S.O)-parameter model, in which both the contribution due to the S.O. coupling of central d3 ion and that of ligands are considered. From the investigations, the signs of zero-field splitting and the local structures of both centers are ob­ tained. The electron paramagnetic resonance parameters D, g^ and g± of both centers are also explained. 
  Reference    Z. Naturforsch. 56a, 326—3 (2001); received February 1 2001 
  Published    2001 
  Keywords    Spin-orbit Coupling, Electron Paramagnetic Resonance (EPR), Crystal-field Theory, Cr3+, NH4CI4 PACS: 7630Fc, 7170Ch 
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 TEI-XML for    default:Reihe_A/56/ZNA-2001-56a-0326.pdf 
 Identifier    ZNA-2001-56a-0326 
 Volume    56