Electron paramagnetic resonance and optical absorption studies of Cu2+ ion doped polyvinyl alcohol films

Electron paramagnetic resonance (EPR) and optical absorption studies have been carried out on Cu²⁺ ions doped in polyvinyl alcohol films (PVA). EPR spectrum at room temperature exhibits hyperfine structure characteristic of Cu²⁺ ions in tetragonal symmetry. The EPR spectra have also been recorded at various temperatures. The number of spins participating in the resonance is measured as a function of temperature and the activation energy is calculated. The paramagnetic susceptibility (χ) is calculated from the EPR data at various temperatures and the Curie constant is evaluated from 1/χ versus T graph. The optical absorption spectrum exhibits a broad band which has been assigned to the transition ²B_1g → ²B_2g.