Exhibition of low hyperfine coupling constant for copper(II) in magnesium rubidium sulphate hexahydrate

Single crystal EPR studies of Cu(II) incorporated in magnesium rubidium sulphate hexahydrate are carried out at RT and 77 K. Since the hyperfine lines are not resolved at RT, single crystal rotations have been carried out at 77 K. The spin Hamiltonian parameters calculated from the 77 K spectra are: g11=2.133g11=2.133, g22=2.137g22=2.137, g33=2.327g33=2.327, A11=0.01A11=0.01, A22=1.44A22=1.44 and A33=10.80mT. The impurity ion occupies an interstitial position in this crystal lattice, which is not very common for copper ion. In addition, the low hyperfine coupling constant is explained by considering an admixture of dx2-y2dx2-y2 ground state with dz2dz2 excited state. Bonding parameters, κ=0.254κ=0.254, P=282.7×10-4cm-1, α2=0.706α2=0.706, α=0.8406α=0.8406 have also been calculated. The present study has helped to understand the static nature of JT, for which the present system is an example.