R. Kripal, S. Pandey
Feb 1, 2011
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Journal
Journal of Physics and Chemistry of Solids
Abstract
Abstract EPR study of the Cr 3+ ion doped l -histidine hydrochloride monohydrate single crystal is done at room temperature. Two magnetically inequivalent interstitial sites are observed. The hyperfine structure for Cr 53 isotope is also obtained. The zero field and spin Hamiltonian parameters are evaluated from the resonance lines obtained at different angular rotations and the parameters are: D =(300±2)×10 −4 cm −1 , E =(96±2)×10 −4 cm −1 , g x =1.9108±0.0002, g y =1.9791±0.0002, g z =2.0389±0.0002, A x =(252±2)×10 −4 cm −1 , A y =(254±2)×10 −4 cm −1 , A z =(304±2)×10 −4 cm −1 for site I and D =(300±2)×10 −4 cm −1 , E =(96±2)×10 −4 cm −1 , g x =1.8543±0.0002, g y =1.9897±0.0002, g z =2.0793±0.0002, A x =(251±2)×10 −4 cm −1 , A y =(257±2)×10 −4 cm −1 , A z =(309±2)×10 −4 cm −1 for site II, respectively. The optical absorption studies of single crystals are also carried out at room temperature in the wavelength range 195–925 nm. Using EPR and optical data, different bonding parameters are calculated and the nature of bonding in the crystal is discussed. The values of Racah parameters ( B and C ), crystal field parameter ( D q) and nephelauxetic parameters ( h and k ) are: B =636, C =3123, D q=2039 cm −1 , h =1.46 and k =0.21, respectively.