ESR of VO in Argon Matrix at 4°K; Establishment of Its Electronic Ground State

ESR spectrum of VO isolated in argon matrix at 4°K was obtained. The analysis of the spectrum led to the unequivocal assignment of its electronic ground state as Σ4 arising from the configuration σ2π4σ1δ2. Due to the extremely large zero-field fine-structure splitting, the entire spectrum was found to be compatible with the effective spin Hamiltonian of the form H = g‖βHzSz + 2g⊥β(HxSx + HySy) + A‖IzSz + 2A⊥(IxSx + IySy), with the following parameters: g‖ = 2.0023 ± 0.001, g⊥ = 1.9804 ± 0.001, A‖ = 714.7 ± 0.5 MHz, and A⊥ = 837.1 ± 0.5 MHz.