Reactions of laser-ablated nickel atoms with dioxygen. Infrared spectra and density functional calculations of nickel oxides NiO, ONiO, Ni₂O₂, and Ni₂O₃, superoxide NiOO, peroxide Ni(O₂), and higher complexes in solid argon

Laser-ablated nickel atoms react with dioxygen to form the primary oxides NiO and ONiO, some of which combine to form the secondary oxides Ni₂O₂ and ONiONiO during condensation in excess argon at 10 K. The insertion product dioxide ONiO is linear based on natural nickel and ¹⁸O isotopic substitution and DFT calculations. Annealing produces the cyclic adducts reported in earlier thermal nickel experiments and the new NiOO superoxide species, which are characterized by isotopic shifts and DFT structure and frequency calculations. In addition, dioxygen complexes with NiO and ONiO were also observed. Finally, the matrix provides sharp bands and the resolution to observe nickel isotopic splittings which characterize the Fermi-resonance interaction in the ONiOO and (O₂)Ni(O₂) molecules.