ESR of copper-doped sodium citrate

Single crystal ESR spectra of Cu2+ ion doped in sodium citrate are reported at room temperature. The observed spectra are fitted to a spin-Hamiltonian of rhombic symmetry with gx=2.1076±0.002, gy=2.1289±0.002, gz=2.4454±0.002, Ax=(40±2)10-4cm-1, Ay=(62±2)10-4cm-1 and Az=(78±2)10-4cm-1. It is found that Cu2+ enters the lattice as a substitutional impurity replacing an Na+ ion. The ground state wave function of Cu2+ ion in this lattice is also determined from the spin-Hamiltonian constants obtained from ESR results. It is found that the ground state is predominantly |x2-y2〉. With the help of the optical absorption study, the nature of bonding in the complex has also been discussed.