# EPR, Optical and IR Studies of $VO^{2+}$ Ions Doped Polyvinylalcohol Films

UNSPECIFIED (2005) EPR, Optical and IR Studies of $VO^{2+}$ Ions Doped Polyvinylalcohol Films. In: 50th DAE Solid State Physics Symposium, Dec. 5 - 9, 2005., Bhabha Atomic Research Centre, Mumbai.

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Electron paramagnetic resonance (EPR), optical and infrared spectral studies have been carried out on vanadyl ions doped in polyvinylalcohol (PVA) films. The spin-Hamiltonian parameters (g and A), bonding parameter $(\beta_{2}^{*2})$, Fermi contact interaction parameter (k) have been evaluated. The values of spin-Hamiltonian parameters confirm that the vanadyl ions are present in PVA films as $VO^{2+}$ molecular ions in an octahedral site with a tetragonal compression. The temperature variation EPR studies reveal that the variation of number of spins with temperature is in accordance with Boltzmann law. It is interesting to observe that the variation of susceptibility with temperature obeys Curie-Weiss law. The FT-IR spectrum exhibits few bands, which are attributed to O-H, C-H, C=C and C-O groups of stretching and bending vibrations. The optical absorption spectrum exhibits two bands $^{2}B_{2g} -> ^{2}B_{1g}$ and $^{2}B_{2g}->^{2}E_{g}$ in the decreasing order of energy. The optical band gap $(E_{opt})$ and the Urbach energies (\Delta E) have also been determined from the ultraviolet absorption edges.