Single Crystal EPR Studies of Mn (II) Doped in Rubidiumcobalt Sulphatehexahydrate: A Case of Interstitial Location

Hema Ramesh^*, S. Sivakumar, M. Rajeswari^, A. Rajappa & K. Mageswari 
Department of chemistry, Sri Manakula Vinayagar Engineering College, Puducherry,India-605107

Abstract
Electron paramagnetic resonance study of Mn²⁺ ion-doped Rubidiumcobalt sulphatehexahydrate (RCSH) single crystal was carried out at X-band frequency to ascertain its structural properties. EPR spectrum exhibits group of five fine structure transitions each splits into six hyperfine components. The spin Hamiltonian parameters calculated from the crystal rotations are: g_xx = 2.040, g_yy = 1.986, g_zz = 1.895, A_xx = 10.25 mT, A_yy = 8.85 mT, A_zz = 8.46 mT, D_xx = 16.68 mT, D_yy = – 5.93 mT, D_zz = −10.74mT, E = 8.09 mT. The detailed study revealed that only one site was present in the lattice interstitially.  From the observed spin Hamiltonian parameters, it was concluded that the site symmetry around the central metal ion was a compressed octahedral with rhombic symmetry. EPR spectra of Mn(II) doped in had been done at room temperature. The direction cosines obtained from the single crystal rotation spectra showed that the paramagnetic impurity had entered the lattice interstitially.  The distortion from axially symmetry for the paramagnetic impurity was noticed, especially in zero-field terms and confirmed the orthorhombic nature of Mn (II).  From the Matumura’s plot, the complex was found to be ionic in nature.  Further studies are planned to calculate spin relaxation with varying temperatures.  FTIR and Powder XRD spectra supported to evaluate lattice parameters within the dopant. 
Keywords: spectrum, Hyperfine, orthorhombic symmetry, Hamiltonian parameters, interstitial.