Laser-induced fluorescence and discharge emission spectra of FeO; Evidence for a 5Δi ground state

Laser-induced fluorescence spectra of gaseous FeO have proved that the bands whose P and R branches have been analyzed rotationally by Harris and Barrow are Ω′ = 4 - Ω″ = 4 transitions. Since the lower state of these bands has the same vibrational frequency as that observed for matrix-isolated FeO at 14 K by Green, Reedy and Kay, the ground state of FeO must contain an Ω = 4 spin-orbit component. Consideration of the low-lying m.o.'s of the transition metal oxides shows that (4sσ) 1(3dδ) 3(3dπ) 2 5Δ i is the only reasonable assignment for the ground state of FeO consistent with this result; the other possible assignments, (4sσ) 2(3dδ) 2(3dπ) 2 5Σ + and (4sσ) 1(3dδ) 2(3dπ) 2(3dσ) 1 7Σ +, do not give rise to Ω = 4 components. © 1981.link_to_subscribed_fulltex