Reactions of laser-ablated copper atoms with dioxygen. Infrared spectra of the copper oxides CuO, OCuO, CuOCuO, and OCuOCuO and superoxide CuOO in solid argon

Laser-ablated copper atoms react directly with O-2 to make CuO (627.7 cm(-1)), and linear OCuO (823.0 cm(-1)) which are identified by copper and oxygen isotopic shifts, comparison to earlier work, and DFT frequency calculations. The highest frequency Cu-O vibration (995.3 cm(-1)) exhibits a resolved copper isotopic triplet appropriate for the vibration of two equivalent copper atoms and oxygen isotopic components consistent with DFT-calculated frequencies for the nearly linear OCuOCuO molecule. Absorptions at 970.0 and 955.1 cm(-1) are assigned to CuOCuO isomers. The simple addition product CuOO is characterized by O-O and Cu-O stretching frequencies at 1089.6 and 550.4 cm(-1), isotopic shifts, and DFT calculations. The CuOO molecule forms higher complexes (O-2)(x)CuOO readily on annealing the matrix sample.