ESR and optical study of Cu²⁺-doped bis-(5,5′-diethylbarbiturato)bis picoline Zn(II)

Abstract

ESR studies were conducted on Cu²⁺-doped bis-(5,5′-diethylbarbiturato)bis picoline Zn(II). Two Cu²⁺ lattice sites, Cu²⁺(I) and Cu²⁺(II), were identified. These sites exhibit two sets of four hyperfine lines in all directions. The g factor and hyperfine splitting were calculated from ESR absorption spectra: g_x  = 2.0201 ± 0.002, g_y  = 2.0900 ± 0.002, g_z  = 2.1634 ± 0.002, A_x  = (30 ± 2) × 10⁻⁴ cm⁻¹, A_y  = (40 ± 2) × 10⁻⁴ cm⁻¹ and A_z  = (154 ± 2) × 10⁻⁴ cm⁻¹. It was found that Cu²⁺ enters the lattice substitutionally. The ground-state wavefunction of the Cu²⁺ ion in this lattice was determined from the spin Hamiltonian constants obtained from the ESR studies. With the help of an optical absorption study, the nature of the bonding in the complex is also discussed.

Keywords:

• ESR
• spin Hamiltonian
• absorption
• angular variation
• rhombic symmetry

Acknowledgements

The authors thank Dr Gundu Rao, Senior Scientific Officer, R.S.I.C., I.I.T. Mumbai, for providing the ESR spectrometer facility. One of the authors, Indrajeet Mishra, thanks the Head of the Physics Department for providing departmental facilities.