REACTIONS OF LASER-ABLATED COBALT ATOMS WITH O-2 - INFRARED-SPECTRA OF COBALT OXIDES IN SOLID ARGON

Laser-ablated Co atoms react with Oz to give the linear dioxide, the m onoxide, and the rhombic (CoO)(2) dimer molecules. The linear OCoO mol ecule is characterized by oxygen-18 substitution in strong nu(3) (945. 4 cm-(1)) fundamental and weak nu(1)+nu(3) (1717.6 cm(-1)) combination bands. Annealing to 20-30 K to allow diffusion and reaction of cold c obalt atoms and dioxygen markedly increases weak bands due to the Co(O z) and CoOO complexes and higher species including OOCoO, OOCoO2, (O-2 )CoO2, and the dimer (CoO2)(2) DFT and CASSCF calculations performed o n the three CoO2 isomers and rhombic (CoO)(2) support these assignment s; DFT calculations are also presented for the rhombic (FeO)(2) molecu le.