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Crystal Research and Technology |
Cryst. Res. Technol. 39,
448 (2004) - Abstract -
Identification of crystal symmetry in Kramers and non-Kramers ions by optical absorption: Divalent copper and nickel ions in diamagnetic lattices
K. Velavan, R. V. S. S. N. Ravikumar*, R. Venkatesan, and P. Sambasiva Rao
Department of Chemistry, Pondicherry University, Pondicherry – 605 014, India
*Department of Advanced Materials Sciences and Engineering, Yamaguchi University, 2-16-1,Tokiwadai, Ube-755-8611, Japan
The optical absorption spectra of Ni(II) doped hexaimidazole zinc(II) dichloride tetrahydrate (HZDT) and Cu(II) doped magnesium potassium phosphate hexahydrate (MPPH) have been studied at room temperature. Ni(II)/HZDT spectrum consists of three strong and one weak band. The calculated value of Dq is 1051 cm-1 and the interelectron repulsion parameters B and C are 854 and 3626 cm-1 respectively. The correlation of optical work with EPR has yielded the spin-orbit interaction parameters λ and ξ as – 225 and – 450 cm-1 respectively. The symmetry around the Ni(II) ion is distorted octahedral, as suggested by EPR results. The estimated percentage covalency of the nickel-nitrogen bond is around 30%. The optical absorption studies of Cu(II)/MPPH show three bands. The octahedral field parameter Dq and the tetragonal field parameters have been evaluated from the observed adsorption bands.
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