Impact of VO²⁺ ions on the electron paramagnetic resonance and optical studies of Zn[CH₂NH₂COOH]SO₄ single crystal: an exploration of spin Hamiltonian and molecular orbital parameters

Abstract

Investigation of the VO²⁺ ions in a single crystal of glycine zinc sulphate (GZS) using electron paramagnetic resonance (EPR) spectroscopy is done at ambient temperature. The single crystal was formed using a solution growth process that slowly evaporated at room temperature. EPR spectrum has been recorded for three mutually orthogonal crystal planes of the prepared GZS single crystal. In the present research work, two identical distinguishable VO²⁺ ion sites have been followed and analyzed. According to the calculated g-principle values, the examination of the hyperfine line positions for all three planes explains why the impurity ion occupies rhombic crystal field symmetry with the surrounding ligands. Additionally, it is revealed that both sites occupy as a substitutional position in the crystal lattice site by taking the place of the zinc ion site, since the effect of spin–orbital motion coupling is dependent on the distinct nature of the paramagnetic ion environment. The optical absorption spectrum of vanadyl ions-doped glycine zinc sulphate was measured in the UV–Vis–NIR range. Comparing Spin Hamiltonian parameters and optical absorption studies, the molecular orbital coefficient values, such as β₁^*2, β₂^*2, e_π^*2, K, (1 − α²), and (1 − γ²), were calculated. From the above data, the ionic bonding nature and contribution of σ, π bonding were found out which decide the different behaviors of electrons affecting the crystal properties. These results indicate that the GZS-VO²⁺ single crystal system could serve as a suitable material for the NLO device application.